Pneumatic tires

Abstract

Provided is a pneumatic tire in which any change in handling stability between low-speed running and high-speed running is sufficiently reduced and durability is sufficiently improved. This pneumatic tire has a belt layer on the radially inner side of the tread portion, wherein the ratio (tanδ / E*) of the loss tangent (tanδ) to the complex elastic modulus E* (MPa) measured under the conditions of 70°C, a frequency of 10 Hz, an initial deformation rate of 5%, and a dynamic deformation rate of 1% of the rubber composition constituting the belt layer is 0.002 to 0.017 (inclusive), and when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, Wt (mm) is the cross-sectional width of the tire, Dt (mm) is the outer diameter, and the virtual volume V (mm) is 3 ) is the volume of the space occupied by the tire, satisfying (Formula 1) and (Formula 2): 1700≤(Dt 2 ×π / 4) / Wt≤2827.4(Formula 1)[(V+1.5×10 7 ) / Wt]≤2.88×10 5 (Formula 2).

Description

Technical Field

[0001] The present disclosure relates to a pneumatic tire. Background Art

[0002] In recent years, from the perspective of increasing environmental concerns and economic benefits, demands for fuel efficiency of motor vehicles have been increasing, and there has also been a strong demand for improved fuel efficiency of pneumatic tires (hereinafter referred to as "tires") mounted on motor vehicles.

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

[0004] To this end, conventionally, proposals have been made to reduce rolling resistance by designing the formulation of a rubber composition constituting a tire tread portion (for example, Patent Documents 1 to 4).

[0005] Prior art literature

[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] Problems to be solved by the present invention

[0012] However, although tires produced by the above-mentioned conventional technologies can reduce rolling resistance, the steering stability may vary significantly between low-speed driving and high-speed driving. These tires are not considered to have sufficient durability.

[0013] Therefore, an object of the present disclosure is to provide a pneumatic tire in which a change in steering stability between low-speed running and high-speed running is sufficiently suppressed, and the durability thereof is sufficiently improved.

[0014] Means of solving the problem

[0015] The present inventors have diligently studied solutions to the above-mentioned problems and have found that the above-mentioned problems can be solved by the following disclosure, thereby completing the present disclosure.

[0016] This disclosure is:

[0017] A pneumatic tire having a belt layer on the radially inner side of a tread portion, wherein:

[0018] The rubber composition constituting the belt layer has a ratio (tanδ / E*) of the loss tangent (tanδ) to the complex elastic modulus (E*: MPa) of 0.002 or more and 0.017 or less, as measured under the conditions of 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%.

[0019] The cross-sectional width of the tire when mounted on a standardized rim and at an internal pressure of 250 kPa is Wt (mm), the outer diameter is Dt (mm), and the volume of the space occupied by the tire is the virtual volume V (mm 3 ), the tire satisfies the following (Formula 1) and (Formula 2):

[0020] 1700 ≤ (Dt 2 ×π / 4) / Wt ≤ 2827.4 (Formula 1)

[0021] [(V+1.5×10 7 ) / Wt]≤2.88×10 5 (Formula 2).

[0022] Effects of the present invention

[0023] According to the present disclosure, it is possible to provide a pneumatic tire in which a change in steering stability between low-speed running and high-speed running is sufficiently suppressed and whose durability is sufficiently improved. DETAILED DESCRIPTION

[0024] [1] Features of the tire disclosed herein

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

[0026] 1. Overview

[0027] First, the tire of the present disclosure is characterized in that it is a pneumatic tire having a belt layer on the radially inner side of a tread portion, wherein the rubber composition constituting the belt layer has a ratio (tanδ / E*) of loss tangent (tanδ) to complex elastic modulus (E*: MPa) of 0.002 or more and 0.017 or less, as measured under the conditions of 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%.

[0028] The tire of the present disclosure is also characterized in that when mounted on a standardized rim and at an internal pressure of 250 kPa, the tire has a cross-sectional width of Wt (mm), an outer diameter of Dt (mm), and a volume of the space occupied by the tire as a virtual volume V (mm). 3 ), the tire satisfies the following (Formula 1) and (Formula 2):

[0029] 1700 ≤ (Dt 2×π / 4) / Wt ≤ 2827.4 (Formula 1)

[0030] [(V+1.5×10 7 ) / Wt]≤2.88×10 5 (Formula 2).

[0031] With respect to the physical properties of the rubber composition forming the belt layer and the tire shape, by providing the above-described properties, a pneumatic tire can be provided in which variation in steering stability between low-speed running and high-speed running is sufficiently suppressed and durability is sufficiently improved.

[0032] In the above description, a "standardized rim" is a rim defined for each tire within the standards system, including the standards to which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it is a standard rim of applicable dimensions described in the "JATMA Yearbook"; in the case of ERTO (European Tire and Rim Technical Organization), it is a "measurement rim" described in the "Standards Manual"; and in the case of TRA (The Tire and Rim Association), it is a "design rim" described in the "Yearbook." For tires not specified in the standards, it refers to a rim that can be assembled and can maintain internal pressure, that is, a rim with a minimum rim diameter and narrowest rim width that does not cause air leakage between the rim and tire.

[0033] The outer diameter Dt of a tire is the outer diameter of the tire when mounted on a standardized rim, at an internal pressure of 250 kPa, and in an unloaded state. The cross-sectional width Wt (mm) of a tire is the width of the tire when mounted on a standardized rim, at an internal pressure of 250 kPa, and in an unloaded state. This width is the distance between the sidewalls (the total width of the tire, including all patterns and text on the tire sidewalls) minus any patterns and text on the tire sidewalls.

[0034] Specifically, the virtual volume V (mm) of the tire is calculated based on the tire outer diameter Dt (mm), the tire cross-section height (the distance from the bead bottom surface to the outermost surface of the tread; 1 / 2 of the difference between the tire outer diameter and the rim nominal diameter) Ht (mm), and the tire cross-section width Wt (mm) when the tire is mounted on a standardized rim with an internal pressure of 250 kPa and no load applied. 3 ) can be calculated using the following formula:

[0035] V=[(Dt / 2) 2 -{(Dt / 2)-Ht} 2 ]×π×Wt.

[0036] 2. Mechanism of the Effects in the Disclosed Tire

[0037] The mechanism by which the effects are exhibited in the tire of the present disclosure (ie, the mechanism by which the change in steering stability between low-speed running and high-speed running is sufficiently suppressed and the durability is sufficiently improved) is presumed as follows.

[0038] (1) Tire shape

[0039] As described above, in the present disclosure, the cross-sectional width Wt (mm) and the outer diameter Dt (mm) of the tire attempt to satisfy:

[0040] 1700≤(Dt 2 ×π / 4) / Wt≤2827.4 (Formula 1).

[0041] By increasing the area of ​​the tire when viewed from the lateral direction relative to the tire's cross-sectional width Wt [(Dt / 2) 2 ×π)=(Dt 2 ×π / 4)] and satisfying the numerical range specified in (Formula 1) is considered to increase the moment of inertia during tire rolling, thereby improving steering stability.

[0042] In (Equation 1), (Dt 2 ×π / 4) / Wt is more preferably 1704 or more, further preferably 1731 or more, further preferably 1733 or more, further preferably 1737 or more, further preferably 1755 or more, further preferably 1758 or more, further preferably 1772 or more, further preferably 1781 or more, further preferably 1789 or more, further preferably 1805 or more, further preferably 1816 or more, further preferably 1822 or more, further preferably 1870 or more, further preferably 1963.4 or more, further preferably 2014 or more, further preferably 2021 or more, further preferably 2032 or more, further preferably 2045 or more, further preferably 2107 or more.

[0043] However, such narrow tires experience significant centrifugal force during rolling, significantly increasing the tire's radius. When impact force is applied to the correspondingly thinner tread portion, there is a risk of damage. Furthermore, when traveling at high speeds, centrifugal force tends to increase the outer diameter, leading to a risk of significant changes in handling stability compared to normal, low-speed travel.

[0044] Therefore, in this disclosure, the imaginary volume V (mm 3 ) and section width Wt (mm) attempt to satisfy:

[0045] [(V+1.5×10 7 ) / Wt]≤2.88×10 5 (Formula 2).

[0046] In this way, it is believed that by reducing the tire's virtual volume V in accordance with the reduction in its cross-sectional width Wt, and by reducing the volume of the tire itself, the increase in the outer diameter due to centrifugal force can be reduced. This is believed to improve the tread's resistance to damage when an impact is applied. Furthermore, by suppressing the increase in the tire's outer diameter, it is believed that changes in steering stability during high-speed driving can also be reduced.

[0047] [(V+1.5×10 7 ) / Wt] is more preferably 2.87×10 5 Below, more preferably 2.85×10 5 Below, more preferably 2.77×10 5 Below, more preferably 2.61×10 5 Below, more preferably 2.55×10 5 Below, more preferably 2.50×10 5 Below, more preferably 2.49×10 5 Below, more preferably 2.42×10 5 Below, more preferably 2.27×10 5 Below, more preferably 2.24×10 5 Below, more preferably 2.21×10 5 Below, more preferably 2.19×10 5 Below, more preferably 2.18×10 5 Below, more preferably 2.17×10 5 Below, more preferably 2.16×10 5 the following.

[0048] In this case, it is more preferable to:

[0049] [(V+2.0×10 7 ) / Wt] ≤ 2.88×10 5 (Formula 3);

[0050] Further preferred:

[0051] [(V+2.5×10 7 ) / Wt]≤2.88×10 5 (Formula 4).

[0052] The above [(V+2.0×10 7 ) / Wt] is more preferably 2.83×10 5 Below, more preferably 2.80×10 5 Below, more preferably 2.77×10 5Below, more preferably 2.76×10 5 Below, more preferably 2.64×10 5 Below, more preferably 2.50×10 5 Below, more preferably 2.49×10 5 Below, more preferably 2.47×10 5 Below, more preferably 2.46×10 5 Below, more preferably 2.45×10 5 Below, more preferably 2.44×10 5 Below, more preferably 2.41×10 5 the following.

[0053] In addition, [(V+2.5×10 7 ) / Wt] is more preferably 2.85×10 5 Below, more preferably 2.78×10 5 Below, more preferably 2.75×10 5 Below, more preferably 2.71×10 5 Below, more preferably 2.69×10 5 Below, more preferably 2.68×10 5 Below, more preferably 2.66×10 5 the following.

[0054] (2) Rubber composition constituting the belt layer

[0055] In the present disclosure, the ratio (tanδ / E*) of the loss tangent (tanδ) to the complex elastic modulus (E*: MPa) measured at 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1% is set to 0.002 or more and 0.017 or less.

[0056] This suppresses belt heating caused by tread deformation during rolling, inhibiting softening. This ensures satisfactory belt rigidity, further minimizing tire outer diameter growth. Consequently, it is believed that variations in handling stability between low- and high-speed driving can be adequately suppressed, significantly improving tire durability.

[0057] (tanδ / E*) is more preferably 0.015 or less, further preferably 0.014 or less, further preferably 0.01 or less, and particularly preferably 0.009 or less. This is believed to further suppress heat generation due to tread deformation during rolling, and satisfactorily ensure the rigidity of the belt layer.

[0058] The above-mentioned loss tangent (tan δ) and complex elastic modulus (E*) can be measured using a viscoelasticity measuring device such as “Eplexor (registered trademark)” manufactured by GABO.

[0059] [2] More preferred embodiments of the tire disclosed herein

[0060] The tire of the present disclosure can achieve better effects by adopting the following embodiments.

[0061] 1. Flatness

[0062] The tire of the present disclosure preferably has an aspect ratio of 40% or more. This increases the area of ​​the side portions and extends the side portions, thereby suppressing changes in the shape of the tread portion during high-speed running and further suppressing an increase in the tire outer diameter.

[0063] The above aspect ratio (%) can be calculated using the following formula using the cross-sectional height Ht (mm) and cross-sectional width Wt (mm) of the tire at an internal pressure of 250 kPa:

[0064] (Ht / Wt)×100(%)

[0065] The flatness is more preferably 41% or more, further preferably 45% or more, further preferably 47.5% or more, further preferably 49% or more, further preferably 50% or more, further preferably 52.5% or more, further preferably 53% or more, further preferably 55% or more, further preferably 58% or more. There is no specific upper limit, but for example, it is 100% or less.

[0066] 2. Relationship between (tanδ / E*) and Wt(mm)

[0067] It is believed that the wider the tire, the larger the contact area, and the greater the contribution of the reaction force caused by the shear deformation of the belt layer. In this state, if the belt layer softens due to heat, it may have a significant impact on handling stability.

[0068] The present inventors determined that to prevent this, it was necessary to reduce the heat generation coefficient of the belt layer (corresponding to the expansion of tire width). They studied the relationship between (tanδ / E*) and Wt ((tanδ / E*) is an index related to belt heat generation, and Wt is an index related to tire width). They discovered that even with wide tires, if [(tanδ / E*) / Wt]×1000≤0.60 (Equation 5) is satisfied, belt deformation and heat generation increases are suppressed, variations are kept to a minimum, and handling stability and durability are improved.

[0069] It was found that [(tan δ / E*) / Wt]×1000 is more preferably 0.55 or less, further preferably 0.08 or less, further preferably 0.07 or less, further preferably 0.06 or less, further preferably 0.05 or less, further preferably 0.04 or less.

[0070] 3. Distance from the tread surface

[0071] Tires have a tread portion of a certain thickness that contacts the road surface. This portion generates heat when in contact with the ground. Since the tread is exposed to the air when it leaves the road, it is possible to maintain a constant temperature. However, increasing tread thickness is thought to make it more difficult to dissipate heat generated in the belt layer into the air.

[0072] The present inventors believe that to prevent this, it is necessary to reduce the distance T (mm) from the tread surface to the belt layer and the coefficient (tan δ / E*), which are indices related to belt heat generation. The present inventors have studied the relationship between the distance T (mm) from the tread surface to the belt layer and this coefficient. They found that if (tan δ / E*) × T ≤ 1.00 (Equation 7) is satisfied, sufficient durability can be achieved even if the belt layer is far from the tread surface.

[0073] Here, if a land portion passes through the equatorial plane, the distance from the tread surface to the belt layer represents the maximum perpendicular distance from the surface of the land portion to the belt layer in the tire cross section. If no land portion passes through the equatorial plane, it represents the maximum perpendicular distance from the surface of the land portion closest to the equatorial plane to the belt layer.

[0074] Then, it was found that (tanδ / E*)×T≤0.85 (Formula 8) is more preferred, and (tanδ / E*)×T is further preferably 0.14 or less, further preferably 0.13 or less, further preferably 0.12 or less, further preferably 0.10 or less, further preferably 0.09 or less, and even more preferably 0.08 or less.

[0075] 4. Tread grooves

[0076] The tire of the present disclosure has a circumferential groove extending continuously in the tire circumferential direction of the tread portion. The groove width L at a depth of 80% of the maximum depth of the circumferential groove is 80 The ratio (L 80 The ratio (L / L) is preferably 0.3 to 0.7. This can suppress the movement of the entire land portion on the bottom surface of the land portion of the tread, thereby effectively suppressing uneven wear of the tread portion and improving durability during high-speed running. This ratio is more preferably 0.35 to 0.65, further preferably 0.40 to 0.60, and particularly preferably 0.45 to 0.55.

[0077] The above L0 and L 80 The straight-line distance (L0) between the groove edges on the tread surface of the circumferential grooves of the tire, and the minimum distance (L0) between the groove walls at a position where the groove depth is 80%, are respectively referred to when the tire is mounted on a standardized rim, at an internal pressure of 250 kPa and without any load applied. 80 ). In short, they can be obtained by pressing the bead portion with a cross section of 2 to 4 cm in width cut out in the radial direction into a state consistent with the rim width.

[0078] The tread portion preferably has a plurality of circumferential grooves, and the total cross-sectional area of ​​the plurality of circumferential grooves is preferably 10 to 30% of the cross-sectional area of ​​the tread portion. This is believed to suppress movement of the tread portion, prevent uneven wear of the tread portion during high-speed driving, and improve durability. It is more preferably 15 to 27%, further preferably 18 to 25%, and particularly preferably 21 to 23%.

[0079] The cross-sectional area of ​​the circumferential groove refers to the total area consisting of the straight line connecting the ends of the circumferential grooves in the tread and the groove walls, in a tire mounted on a standardized rim, at an internal pressure of 250 kPa, and in the unloaded state. Simply put, this area is achieved by pressing the bead portion, cut in the radial direction with a cross-section width of 2 to 4 cm, to a state that matches the rim width.

[0080] Furthermore, the tread preferably has a plurality of axially extending transverse grooves, with the total volume of the plurality of transverse grooves accounting for 2.0% to 5.0% of the tread volume. This is believed to suppress tread movement, prevent uneven wear, and improve durability. More preferably, the volume is 2.2 to 4.0%, further preferably 2.5 to 3.5%, and particularly preferably 2.7 to 3.0%.

[0081] The volume of the transverse grooves described above refers to the total volume consisting of the surface connecting the transverse groove ends and the groove walls, in a tire mounted on a standardized rim, at an internal pressure of 250 kPa, and in an unloaded state. Simply put, it can be calculated by calculating the volume of each transverse groove, multiplying the area by the number of grooves, with the bead portion cut out in a radially 2 to 4 cm wide section pressed to match the rim width. Alternatively, the volume of the tread portion can be calculated by calculating the area of ​​the section excluding the transverse grooves, multiplying this area by the outer diameter, and then calculating the difference between this calculated area and the transverse groove volume.

[0082] In order to suppress uneven wear of the tread portion and further improve durability, the lateral grooves preferably include lateral grooves having a groove width Gw to groove depth Gd ratio (Gw / Gd) of 0.50 to 0.80. This ratio is more preferably 0.53 to 0.77, further preferably 0.55 to 0.75, and particularly preferably 0.60 to 0.70.

[0083] The groove width and groove depth of the lateral grooves described above refer to the maximum length (perpendicular to the groove direction) of a straight line connecting the tread surface ends of the lateral groove and the maximum depth of the lateral groove, respectively, in a tire under an internal pressure of 250 kPa and no load. Simply put, this can be calculated by pressing the bead portion, with a radial cross-section of 2 to 4 cm, to the width of the rim.

[0084] 5. Tire shape

[0085] In the tire disclosed herein, when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the specific outer diameter Dt (mm) is preferably, for example, 515 mm or more, more preferably 558 mm or more, further preferably 585 mm or more, further preferably 648 mm or more, further preferably 658 mm or more, further preferably 662 mm or more, further preferably 64 mm or more, further preferably 665 mm or more, further preferably 671 mm or more, and most preferably 673 mm or more.

[0086] On the other hand, it is preferably less than 843mm, more preferably less than 735mm, further preferably less than 725mm, further preferably less than 719mm, further preferably less than 717mm, further preferably less than 716mm, further preferably less than 714mm, further preferably less than 711mm, further preferably less than 707mm, further preferably less than 691mm, further preferably less than 690mm, further preferably less than 685mm, further preferably less than 680mm, further preferably less than 675mm.

[0087] The specific cross-sectional width Wt (mm) is preferably 115 mm or more, more preferably 130 mm or more, further preferably 150 mm or more, further preferably 170 mm or more, further preferably 174 mm or more, further preferably 175 mm or more, further preferably 176 mm or more, further preferably 178 mm or more, further preferably 181 mm or more, further preferably 183 mm or more, further preferably 175 mm or more, particularly preferably 185 mm or more, and most preferably 193 mm or more.

[0088] On the other hand, it is preferably less than 305mm, more preferably less than 245mm, further preferably less than 235mm, further preferably less than 231mm, further preferably less than 230mm, further preferably less than 229mm, further preferably less than 228mm, further preferably less than 224mm, further preferably less than 210mm, further preferably less than 205mm, further preferably less than 203mm, further preferably less than 202mm, further preferably less than 200mm.

[0089] For example, the specific cross-sectional height Ht (mm) is preferably 37 mm or more, more preferably 69 mm or more, further preferably 70 mm or more, further preferably 71 mm or more, further preferably 77 mm or more, further preferably 78 mm or more, further preferably 79 mm or more, further preferably 80 mm or more, further preferably 87 mm or more, further preferably 89 mm or more, further preferably 90 mm or more, further preferably 95 mm or more, further preferably 96 mm or more, further preferably 98 mm or more, further preferably 99 mm or more.

[0090] On the other hand, it is preferably less than 180 mm, more preferably 116 mm or less, further preferably 114 mm or less, further preferably less than 112 mm, further preferably 104 mm or less, further preferably 101 mm or less.

[0091] The specific virtual volume V is preferably 13,000,000 mm 3 More than 22,706,213 mm, more preferably 3 More preferably, 23,338,766 mm 3 More preferably, 23,576,710 mm 3 More preferably 28,585,634 mm 3 Above, more preferably 28,719,183 mm 3 More than, more preferably 29,000,000 mm 3 Above, more preferably 29,087,378 mm 3 Above, more preferably 30, 132, 749 mm 3 Above, more preferably 30, 495, 603 mm 3 Above, more preferably 34, 138, 255 mm 3 Above, more preferably 35,836,776 mm 3 More preferably, 36,000,000 mm 3Above, more preferably 36, 203, 610 mm 3 Above, more preferably 36,418,787 mm 3 Above, more preferably 36,616,393 mm 3 Above, more preferably 36,682,357 mm 3 above.

[0092] On the other hand, it is preferably less than 66,000,000 mm 3 , more preferably 52, 265, 389 mm 3 Less than, more preferably less than 44,000,000 mm 3 , more preferably 43,355,989 mm 3 Below, more preferably 41,835,961 mm 3 Below, more preferably 40, 755, 756 mm 3 Less than, more preferably less than 38,800,000 mm 3 .

[0093] In addition, in the present disclosure, considering the stability of driving comfort during driving, (Dt-2×Ht) is preferably greater than 450 mm, more preferably greater than 456 mm, further preferably greater than 458 mm, further preferably greater than 470 mm, further preferably greater than 480 mm, further preferably greater than 482 mm, further preferably greater than 483 mm, and further preferably greater than 484 mm.

[0094] On the other hand, considering the deformation of the tread portion, it is preferably less than 560mm, more preferably less than 559mm, further preferably less than 558mm, further preferably less than 534mm, further preferably less than 533mm, further preferably less than 530mm, further preferably less than 510mm, further preferably less than 509mm, further preferably less than 508mm, further preferably less than 507mm.

[0095] [3] Implementation

[0096] Hereinafter, the present disclosure will be described in detail based on embodiments.

[0097] 1. Rubber composition constituting the belt layer

[0098] (1) Compounding materials

[0099] The rubber composition constituting the belt layer of the tire of the present disclosure can be obtained from the rubber component described below and other compounding materials.

[0100] (a) Rubber component

[0101] In an embodiment of the present invention, as the rubber component, a rubber (polymer) commonly used for producing tires, such as isoprene-based rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR) and acrylonitrile-butadiene rubber (NBR) can be used. Among these, isoprene-based rubber is preferred, and BR and SBR can be used in combination as needed.

[0102] (a-1) Isoprene rubber

[0103] The content (total content) 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.

[0104] Examples of the isoprene-based rubber include natural rubber (NR), isoprene-based rubber (IR), modified NR, modified NR, and modified IR. Among these, NR is preferred from the viewpoint of excellent strength.

[0105] As NR, for example, SIR20, RSS#3, TSR20, etc. commonly used in the tire industry can be used. There are no particular restrictions on IR, and for example, IR2200, which is common in the tire industry, can be used. Modified NR includes deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. Modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Modified IR includes epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. These can be used alone or in combination of two or more.

[0106] (a-2)BR

[0107] In the embodiment of the present invention, if necessary, 5 parts by mass or more and 25 parts by mass or less of BR may be used in the rubber component together with NR.

[0108] For example, the weight average molecular weight of BR is greater than 100,000 and less than 2,000,000. For example, the vinyl bond content (1,2-bonded butadiene unit content) of BR is greater than 1% by mass and less than 30% by mass. For example, the cis content of BR is greater than 1% by mass and less than 98% by mass. For example, the trans content of BR is greater than 1% by mass and less than 60% by mass. The cis content can be measured by infrared absorption spectroscopy.

[0109] BR is not particularly limited, and BR with a high cis content (cis content of 90% or more), BR with a low cis content, BR containing syndiotactic polybutadiene crystals, etc. can be used. BR can be unmodified BR or modified BR. Modified BR can be, for example, S-modified BR modified with a compound (modifier) ​​represented by the following formula.

[0110] [Chemistry 1]

[0111]

[0112] Where R 1 、R 2 and R 3 represents the same or different alkyl groups, alkoxy groups, silyl groups, acetal groups, carboxyl groups (-COOH), mercapto groups (-SH) or derivatives thereof. 4 and R 5 R represents the same or different hydrogen atoms or alkyl groups. 4 and R 5 It can combine with nitrogen to form a ring structure. n represents an integer.

[0113] Examples of the BR modified with the compound (modifying agent) represented by the above formula include BR whose polymer terminal (active terminal) has been modified with the compound represented by the above formula.

[0114] As R 1 、R 2 and R 3 , 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 , 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, when R 4 and R 5 When the alkoxy group forms a ring structure together with a nitrogen atom, it is preferably a 4- to 8-membered ring. Alkoxy groups also include cycloalkoxy groups (eg, cyclohexyloxy groups) and aryloxy groups (eg, phenoxy groups, benzyloxy groups).

[0115] Specific examples of the above-mentioned 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.

[0116] In addition, as modified SBR, modified SBR modified with the following compounds (modifiers) can also be used. Examples of the modifier include:

[0117] Polyglycidyl ethers of polyols, such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether;

[0118] Polyglycidyl ethers of aromatic compounds having two or more phenolic groups, such as diglycidyl bisphenol A;

[0119] Polyepoxides, such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene;

[0120] Epoxy-containing tertiary amines, such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine;

[0121] Diglycidylamino compounds, for example diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl-o-toluidine, tetraglycidyl-m-xylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane and tetraglycidyl-1,3-bisaminomethylcyclohexane;

[0122] Acid chlorides containing amino groups, such as bis-(1-methylpropyl)carbamoyl chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamoyl chloride and N,N-diethylcarbamoyl chloride;

[0123] Epoxy-containing silane compounds, such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane;

[0124] Silane compounds containing a thioether group, 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, and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide;

[0125] N-substituted aziridine compounds, such as ethyleneimine and propyleneimine;

[0126] Alkoxysilanes, for example methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane;

[0127] (Thio)benzophenone compounds having an amino group and / or a substituted amino group, for example, 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;

[0128] Benzaldehyde compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde;

[0129] N-substituted pyrrolidones, for example N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone and N-methyl-5-methyl-2-pyrrolidone;

[0130] N-substituted piperidones, such as N-methyl-2-piperidone, N-vinyl-2-piperidone and N-phenyl-2-piperidone;

[0131] N-substituted lactams, for example N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-lauryl lactam, N-vinyl-ω-lauryl lactam, N-methyl-β-propiolactam and N-phenyl-β-propiolactam;

[0132] N,N-bis-(2,3-epoxypropyloxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), 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-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone and 1,7-bis(methylethylamino)-4-heptanone.

[0133] The modification with the above-mentioned compound (modifying agent) can be performed by a known method.

[0134] As modified BR, for example, tin-modified BR can also be used. Preferred tin-modified BRs are those obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, wherein the terminals of the tin-modified BR molecules are bonded via tin-carbon bonds.

[0135] Examples of lithium initiators include lithium compounds such as alkyl lithium, aryl lithium, vinyl lithium, organotin lithium, and organonitrogen lithium compounds, as well as metallic lithium. By using a lithium initiator as an initiator for tin-modified BR, tin-modified BR with a high vinyl content and a low cis content can be produced.

[0136] Examples of the tin compound include tin tetrachloride, butyltin trichloride, dibutyltin dichloride, dioctyltin dichloride, tributyltin chloride, triphenyltin chloride, dibutyldiphenyltin, ethoxytriphenyltin, dimethyldiphenyltin, ditolyltin chloride, diphenyltin dioctoate, divinyldiethyltin, tetrabenzyltin, dibutyltin distearate, tetraallyltin, and tributylphenyltin.

[0137] 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, even more preferably 250 ppm or less.

[0138] Furthermore, the molecular weight distribution (Mw / Mn) of the tin-modified BR is preferably 2 or less, more preferably 1.5 or less.

[0139] The vinyl bond 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 bond content in the tin-modified BR is preferably 50% by mass or less, more preferably 20% by mass or less.

[0140] The above-mentioned S-modified BR and tin-modified BR may be used alone or in combination of two or more.

[0141] As BR, for example, products produced by Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used.

[0142] (a-3)SBR

[0143] In an embodiment of the present invention, the rubber component may contain 5 to 25 parts by mass of SBR together with NR, if necessary, and SBR may be used in combination with the above-mentioned BR.

[0144] The weight average molecular weight of SBR is preferably greater than 100,000 and less than 2,000,000. For example, the styrene content of SBR is preferably greater than 5 mass %, more preferably greater than 10 mass %, even more preferably greater than 20 mass %. On the other hand, it is preferably less than 50 mass %, more preferably less than 40 mass %, even more preferably less than 35 mass %. For example, the vinyl bond amount of SBR is preferably greater than 5 mass % and less than 70 mass %. The structural evaluation (measuring styrene content and vinyl bond amount) of SBR can be carried out using the JNM-ECA series instruments produced by JEOL Co., Ltd.

[0145] SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR). SBR may be unmodified SBR or modified SBR, and these may be used alone or in combination of two or more.

[0146] Modified SBR can be any SBR with functional groups that interact with fillers (such as silica). Examples include:

[0147] Terminal-modified SBR (terminal-modified SBR having the above-mentioned functional group at the terminal), in which at least one terminal of the SBR is modified with a compound (modifying agent) having the above-mentioned functional group;

[0148] Main chain modified SBR with functional groups on the main chain;

[0149] Main chain terminal modified SBR having functional groups on both the main chain and the terminal (for example, main chain terminal modified SBR having the above functional groups on the main chain and at least one terminal modified with the above modifier); and

[0150] Terminal-modified SBR that is modified (coupled) with a multifunctional compound having two or more epoxy groups in the molecule and into which epoxy groups or hydroxyl groups are introduced.

[0151] As the SBR, for example, SBR produced and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used. The SBR can be used alone or in combination of two or more.

[0152] (a-4) Other rubber components

[0153] Furthermore, as another rubber component, the rubber composition may contain, if necessary, a rubber (polymer) generally used for producing tires, such as acrylonitrile-butadiene rubber (NBR).

[0154] (b) Compounding materials other than the rubber component

[0155] (b-1) Filler

[0156] In an embodiment of the present invention, the rubber composition preferably contains a filler. Specific examples of fillers include carbon black, silica, calcium carbonate, talc, aluminum oxide, clay, aluminum hydroxide, and mica. Among these, carbon black can be preferably used as a reinforcing agent. If necessary, silica is also preferably used as a reinforcing agent. In this case, it is preferably used in combination with a silane coupling agent.

[0157] (i) Carbon black

[0158] The rubber composition preferably contains carbon black. For example, the amount of carbon black per 100 parts by mass of the rubber component is 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.

[0159] Carbon black is not particularly limited, and examples include furnace blacks such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black; thermal blacks such as FT and MT; channel blacks such as EPC, MPC, and CC; and graphite. These can be used alone or in combination of two or more.

[0160] For example, the nitrogen adsorption specific surface area (N2SA) of carbon black is greater than 30m 2 / g and less than 250m 2 / g. For example, the amount of dibutyl phthalate (DBP) absorbed by carbon black is greater than 50 ml / 100 g and less than 250 ml / 100 g. The nitrogen adsorption specific surface area of ​​carbon black is measured according to ASTM D4820-93, and the amount of DBP absorbed is measured according to ASTM D2414-93.

[0161] The specific carbon black is not particularly limited, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include, for example, those of Asahi Carbon Co., Ltd., Cabot Japan Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., and the like. These can be used alone or in combination of two or more.

[0162] (ii) Silicon dioxide

[0163] If necessary, the rubber composition also preferably contains silica. From the perspective of obtaining good durability, the BET specific surface area of ​​silica is preferably greater than 140 m 2 / g, more preferably greater than 160m 2 / g. On the other hand, from the perspective of obtaining good rolling resistance under high-speed running, it is preferably less than 250m 2 / g, more preferably less than 220m 2 / g.

[0164] Furthermore, when a silane coupling agent is not used in combination, the silica content is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, per 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 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 above-mentioned BET specific surface area is the value of N2SA measured by the BET method according to ASTM D3037-93.

[0165] Examples of silica include dry-process silica (anhydrous silica) and wet-process silica (hydrous silica). Of these, wet-process silica is preferred because it has a large number of silanol groups.

[0166] As silica, for example, products of Degussa, Rhodia, Tosoh Silicon Corporation, Solvay Japan Ltd., Tokuyama Corporation, and the like can be used.

[0167] (iii) Silane coupling agent

[0168] As described above, when using silica, a silane coupling agent may be used together with the silica. The silane coupling agent is not particularly limited. Examples of silane coupling agents include:

[0169] 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, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide bis(trimethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide and 3-triethoxysilylpropyl methacrylic acid monosulfide;

[0170] Mercapto-based silane coupling agents, such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, NXT, and NXT-Z (both available from Momentive);

[0171] Vinyl silane coupling agents, such as vinyltriethoxysilane and vinyltrimethoxysilane; amino silane coupling agents, such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane;

[0172] Glycidoxy-based silane coupling agents, such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane;

[0173] Nitro-based silane coupling agents, such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and

[0174] Chlorine-based silane coupling agents, such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane.

[0175] These can be used alone or in combination of two or more.

[0176] As the silane coupling agent, for example, products of Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Dow Corning Toray Industries, Ltd., and the like can be used.

[0177] For example, the content of the silane coupling agent is greater than 3 parts by mass and less than 15 parts by mass relative to 100 parts by mass of silica.

[0178] (iv) Other fillers

[0179] In addition to the carbon black and silica described above, the rubber composition may also contain fillers commonly used in the tire industry, such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. For example, the content of these fillers is greater than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0180] (b-2) Curable resin component

[0181] The rubber composition preferably contains a curable resin component such as a modified resorcinol resin and a modified phenolic resin. This makes it possible to improve adhesion to the steel cord without greatly deteriorating heat generation and elongation at break.

[0182] For example, the content of the curable resin component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more relative to 100 parts by mass of the rubber component. On the other hand, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less.

[0183] Specific examples of the modified resorcinol resin include Sumikanol 620 (modified resorcinol resin) manufactured by Taoka Chemical Co., Ltd.; examples of the modified phenolic resin include PR12686 (cashew nut oil-modified phenolic resin) manufactured by Sumitomo Bakelite Co., Ltd.

[0184] When using a modified resorcinol resin, it is preferred to include a methylene donor as a curing agent. Examples of methylene donors include hexamethylenetetramine (HMT), hexamethoxymethylmelamine (HMMM), and hexamethylolmelamine pentamethyl ether (HMMPME). It is preferably contained in an amount of 5 parts by mass or more and about 15 parts by mass.

[0185] As a specific methylene donor, for example, Sumikanol 507 manufactured by Taoka Chemical Co., Ltd. can be used.

[0186] (b-3) Resin component

[0187] In addition, from the perspective of operability (imparting viscosity), if necessary, the rubber composition preferably includes a resin component. The resin component can be solid or liquid at room temperature, and specific resin components include rosin-based resins, styrene resins, coumarone resins, terpene resins, C5 resins, C9 resins, C5C9 resins, acrylic resins, etc. Two or more resin components can be used in combination. Relative to 100 parts by mass of the rubber component, the content of the resin component is preferably greater than 2 parts by mass and less than 45 parts by mass, more preferably less than 30 parts by mass.

[0188] Rosin-based resin is a resin whose main component is rosin acid obtained by processing rosin. Rosin-based resin (rosin) can be classified according to whether it has been modified and can be divided into unmodified rosin (natural 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 rosins are modified unmodified rosins, and examples include rosin esters, unsaturated carboxylic acid-modified rosin, unsaturated carboxylic acid-modified rosin esters, rosin amide compounds, and rosin amine salts.

[0189] Styrene resins are polymers using styrene monomers as constituent monomers, and examples include polymers obtained by polymerizing styrene monomers as a main component (50% by mass or more). Specifically, they 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.), copolymers obtained by copolymerizing two or more styrene monomers, and copolymers obtained by copolymerizing styrene monomers and other monomers copolymerizable with styrene monomers.

[0190] Examples of other monomers include: acrylonitriles such as acrylonitrile and methacrylate; 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 and isoprene; olefins such as 1-butene and 1-pentene; α,β-unsaturated carboxylic acids such as maleic anhydride and its anhydride.

[0191] As the coumarone-based resin, coumarone-indene resin is preferred. Coumarone-indene resin is a resin containing coumarone and indene as monomer components constituting the resin backbone (main chain). Examples of monomer components other than coumarone and indene contained in the backbone include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0192] For example, the content of the coumarone-indene resin is greater than 1.0 part by mass and less than 50.0 parts by mass relative to 100 parts by mass of the rubber component.

[0193] For example, the hydroxyl value (OH value) of coumarone-indene resin is greater than 15 mgKOH / g and less than 150 mgKOH / g. The OH value is the amount of potassium hydroxide required to neutralize acetic acid bound to hydroxyl groups when 1 g of the resin is acetylated, and is expressed in mg. It is a value measured by potentiometric titration (JIS K 0070:1992).

[0194] For example, the softening point of coumarone-indene resin is greater than 30° C. and less than 160° C. The softening point is the temperature at which a ball falls when measuring the softening point defined in JIS K 6220-1:2001 using a ring-and-ball softening point measuring device.

[0195] Examples of terpene resins include polyterpene, terpene phenol and aromatic modified terpene resins. Polyterpene is a resin obtained by polymerizing terpene compounds and their hydrogenation products. Terpene compounds refer to compounds having a structure consisting of (C5H8) n The hydrocarbon compound or its oxygen-containing derivatives are represented by the composition, which is a compound having terpene as the basic skeleton. Terpene can be classified into monoterpene (C 10 H 16 ), sesquiterpenes (C 15 H 24 ) or diterpenes (C 20 H 32 Examples 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.

[0196] Examples of polyterpenes include terpene resins made from the above-mentioned terpene compounds, such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin, as well as hydrogenated terpene resins obtained by hydrogenating terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the above-mentioned terpene compounds and phenol compounds, and resins obtained by hydrogenating the above-mentioned resins. Specifically, resins obtained by condensing the above-mentioned terpene compounds, phenol compounds, and formalin can be mentioned. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylene. 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 include: phenolic compounds such as phenol, alkylphenol, alkoxyphenol and phenol containing an unsaturated hydrocarbon group; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol and naphthol containing an unsaturated hydrocarbon group; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene and styrene containing an unsaturated hydrocarbon group; as well as coumarone and indene.

[0197] 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. As a C5-based petroleum resin, dicyclopentadiene resin (DCPD resin) is preferably used.

[0198] C9 resin refers to a resin obtained by polymerizing a C9 fraction, which can be hydrogenated or modified. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene and methylindene. As specific examples, coumarone-indene resins, coumarone resins, indene resins and aromatic vinyl resins are preferably used. As aromatic vinyl resins, preferably α-methylstyrene or a homopolymer of styrene or a copolymer of α-methylstyrene and styrene is because it is economical, easy to process, and has excellent heat-generating properties. More preferably, a copolymer of α-methylstyrene and styrene is used. As aromatic vinyl resins, those purchased from, for example, Creighton Corporation, Eastman Chemical Company, etc. can be used.

[0199] C5C9 resin refers to a resin obtained by copolymerizing C5 fraction and C9 fraction, and the resin may be hydrogenated or modified. Examples of C5 fraction and C9 fraction include the above-mentioned petroleum fractions. As C5C9 resin, those purchased from, for example, Tosoh Corporation, LUHUA, etc. can be used.

[0200] The acrylic resin is not particularly limited, but for example, a solvent-free acrylic resin can be used.

[0201] Examples of solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized by a high-temperature continuous polymerization method (high-temperature continuous block polymerization method: methods described in US Pat. No. 4,414,370B, JP 84-6207A, JP 93-58805A, JP 89-313522A, US Pat. No. 5,010,166B, and Toa Synthetic Research Annual Report TREND 2000, Vol. 3, pp. 42-45, etc.), thereby minimizing the use of polymerization initiators, chain transfer agents, organic solvents, and the like as auxiliary raw materials. In the present disclosure, (meth)acrylic acid refers to methacrylic acid and acrylic acid.

[0202] Examples of monomer components constituting the acrylic resin include (meth)acrylic acid and (meth)acrylic acid derivatives such as (meth)acrylates (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylamide derivatives.

[0203] In addition, as monomer components constituting the acrylic resin, aromatic vinyl compounds (eg, styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinylnaphthalene, etc.) and (meth)acrylic acid or (meth)acrylic acid derivatives can be used.

[0204] The acrylic resin may be a resin composed only of a (meth)acrylic component, or a resin further having a component other than a (meth)acrylic component. In addition, the acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

[0205] As the resin component, for example, products of Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemical Co., Ltd., BASF Corporation, Arizona Chemical Co., Ltd., Nitto Chemical Co., Ltd., Nippon Catalyst Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd. can be used.

[0206] (b-4) organic acid cobalt

[0207] The rubber composition preferably contains an organic acid cobalt. Since the organic acid cobalt crosslinks the cord and rubber, its inclusion improves the adhesion between the cord and rubber. The cobalt concentration in the rubber composition is preferably 500 ppm or greater, more preferably 700 ppm or greater, and even more preferably 900 ppm or greater. On the other hand, it is preferably 1500 ppm or less, and more preferably 1300 ppm or less.

[0208] Examples of the organic acid cobalt include cobalt stearate, cobalt naphthenate, cobalt neodecanoate, and cobalt boron-3 neodecanoate.

[0209] (b-5) Anti-reversion agent (anti-sulfurization reversion agent)

[0210] If necessary, the rubber composition preferably includes an anti-reversion agent (anti-vulcanization reversion agent). This can inhibit reversion and improve durability. Relative to 100 parts by mass of the rubber component, the content of the anti-reversion agent is preferably 0.1 parts by mass or more and 3 parts by mass or less, more preferably 0.2 parts by mass or more and 2.5 parts by mass or less, and further preferably 0.3 parts by mass or more and 2 parts by mass or less. As a specific anti-reversion agent, for example, Parkalink 900 (1,3-bis(citric acid imide methyl)benzene) produced by Flex Corporation can be used.

[0211] (b-6) Anti-aging agent

[0212] The rubber composition preferably contains an anti-aging agent. For example, the amount of the anti-aging agent is greater than 1 part by mass and less than 10 parts by mass, more preferably 1.5 parts by mass or more, per 100 parts by mass of the rubber component.

[0213] Examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based anti-aging agents 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 anti-aging agents such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; monophenol-based anti-aging agents such as 2,6-di-tert-butyl-4-methylphenol and styrenated phenol; and bisphenol-based anti-aging agents, triphenol-based anti-aging agents, or polyphenol-based anti-aging agents such as tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. These can be used alone or in combination of two or more.

[0214] As the anti-aging agent, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flextronics Co., Ltd., etc. can be used.

[0215] (b-7) stearic acid

[0216] The rubber composition may contain stearic acid. The content of stearic acid per 100 parts by mass of the rubber component is, for example, greater than 0.5 parts by mass and less than 10.0 parts by mass, more preferably at least 1 part by mass. Conventional stearic acid can be used, for example, products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., and the like.

[0217] (b-8) Zinc oxide

[0218] The rubber composition may contain zinc oxide. The zinc oxide content per 100 parts by mass of the rubber component is, for example, greater than 0.5 parts by mass and less than 15 parts by mass, more preferably 10 parts by mass or greater, and even more preferably 11 parts by mass or greater. Conventional zinc oxide can be used, and for example, products from Mitsui Mining & Smelting Co., Ltd., Toho Asia Lead Co., Ltd., Shiromizu Techno Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Co., Ltd., and the like can be used.

[0219] (b-9) Crosslinking agent and vulcanization accelerator

[0220] The rubber composition preferably contains a crosslinking agent (eg, sulfur) in an amount of, for example, greater than 0.1 parts by mass and less than 10.0 parts by mass, and more preferably 7 parts by mass or more, per 100 parts by mass of the rubber component.

[0221] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur, all of which are commonly used in the rubber industry. These can be used alone or in combination of two or more.

[0222] As sulfur, for example, products of Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flex Corporation, Nippon Senryu Industry Co., Ltd., Hosoi Chemical Co., Ltd., etc. can be used.

[0223] Examples of cross-linking 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 Flexex, and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by LANXESS; and organic peroxides such as dicumyl peroxide.

[0224] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator is, for example, greater than 0.3 parts by mass and less than 10.0 parts by mass, and more preferably 1.2 parts by mass or more, per 100 parts by mass of the rubber component.

[0225] Examples of vulcanization accelerators include:

[0226] Thiazole vulcanization accelerators, such as 2-mercaptobenzothiazole, di-2-benzothiazole disulfide, and N-cyclohexyl-2-benzothiazole sulfenamide;

[0227] Thiuram-based vulcanization accelerators, such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N);

[0228] Sulfenamide-based vulcanization accelerators, such as N-cyclohexyl-2-benzothiazolesulfenamide, N-tert-butyl-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and

[0229] Guanidine-based vulcanization accelerators, such as diphenylguanidine, di-o-tolylguanidine and o-tolylbiguanidine.

[0230] These can be used alone or in combination of two or more.

[0231] (b-10) Other

[0232] In addition to the above components, the rubber composition may also contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, and organic peroxides, in an amount of, for example, greater than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0233] (2) Production of tread rubber composition

[0234] The rubber composition is produced by a conventional method, for example, a production method including a basic kneading step of kneading a rubber component and a filler such as carbon black and a final kneading step of kneading a kneaded product obtained in the basic kneading step and a crosslinking agent.

[0235] Kneading can be carried out using known (sealed) kneading machines such as a Banbury mixer, a kneader or an open roll mill.

[0236] The kneading temperature of the basic kneading step is, for example, greater than 50° C. and less than 200° C., and the kneading time is, for example, greater than 30 seconds and less than 30 minutes. In the basic kneading process, in addition to the above components, compounding agents commonly used in the rubber industry, such as softeners (e.g., oils), stearic acid, zinc oxide, anti-aging agents, waxes, and vulcanization accelerators, may be appropriately added as needed and kneaded.

[0237] In the final kneading step, the kneaded product obtained in the base kneading step and the crosslinking agent are kneaded. The kneading temperature in the final kneading step is, for example, greater than room temperature and less than 80°C, and the kneading time is, for example, greater than 1 minute and less than 15 minutes. In the final kneading step, in addition to the above-mentioned components, a vulcanization accelerator, zinc oxide, etc. may be added as needed and kneaded.

[0238] 2. Production of belt components

[0239] A belt member can be produced by covering the obtained rubber composition on the upper and lower sides of steel cords arranged in parallel.

[0240] 3. Tire production

[0241] The tire of the present disclosure is produced by a conventional method using the unvulcanized rubber composition obtained by the final kneading step. In other words, first, an unvulcanized tire is produced by molding the belt component obtained above together with other tire components on a tire molding machine in a conventional manner.

[0242] Specifically, the inner liner (which ensures the tire's airtightness), carcass (which bears the load, impact, and inflation pressure applied to the tire), and belt components (which strongly tighten the carcass to increase tread rigidity) are wound around a forming drum. The carcass' ends are secured to the edges, and the beads (which secure the tire to the rim) are arranged and formed into a toroidal shape. The tread is then attached to the center of the outer circumference, and the sidewalls are attached radially outward, resulting in an unvulcanized tire.

[0243] In embodiments of the present invention, from the perspectives of increasing the bonding force during running and more easily suppressing outer diameter growth, the steel cords in the belt layer are preferably arranged at an angle of 15° or greater relative to the tire circumferential direction. This angle is more preferably 18° or greater, and even more preferably 23° or greater. On the other hand, if this angle is too large, the movement during cornering becomes excessive. Therefore, this angle is preferably 50° or less, more preferably 45° or less, and even more preferably 35° or less.

[0244] The angle of the steel cord is the angle of the steel cord relative to the tire circumferential direction when the tire is not filled with air, and can be confirmed by peeling off the tread portion from the radially outer side of the tire.

[0245] The unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire. The vulcanization step can be performed by applying 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.

[0246] At this time, when the tire is mounted on a standardized rim and the internal pressure is set to 250 kPa, the tire has a shape that satisfies the above-mentioned (Formula 1) and (Formula 2).

[0247] Specific tires that can meet the above (Formula 1) and (Formula 2) include tires with size symbols of 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.

[0248] In an embodiment of the present invention, a tire that can satisfy (Formula 1) and (Formula 2) is preferably used in a pneumatic tire for a passenger car. Satisfying the above formula can more advantageously solve the problem in the present disclosure (providing a pneumatic tire that can not only sufficiently reduce rolling resistance under high-speed driving, but also sufficiently improve the handling performance changes and durability at low and high speeds).

[0249] Example

[0250] Hereinafter, the present disclosure will be described in more detail with reference to examples.

[0251] [Experiment 1]

[0252] In this experiment, a 175 size tire was prepared and evaluated.

[0253] 1. Production of rubber composition for belts

[0254] First, a belt rubber composition is produced.

[0255] (1) Compounding materials

[0256] First, each compounding material shown below was prepared.

[0257] (a) Rubber component

[0258] NR:RSS3

[0259] (b) Compounding materials other than the rubber component

[0260] (b-1) Carbon black 1: Show Black N326 (N2SA: 78m 2 / g)

[0261] (b-2) Carbon black 2: Show Black N550 (N2SA: 42m 2 / g)

[0262] (b-3) Curable resin component 1: PR12686 (cashew nut oil-modified phenolic resin) manufactured by Sumitomo Bakelite Co., Ltd.

[0263] (b-4) Curable resin component 2: Sumikanol 620 (modified resorcinol resin) manufactured by Taoka Chemical Co., Ltd.

[0264] (b-5) Curing agent: Sumikanol 507 (methylene donor) manufactured by Taoka Chemical Co., Ltd.

[0265] (b-6) Organic cobalt acid: DICNATE NBC-2 (cobalt boroneodecanoate, cobalt content 22.5% by mass) manufactured by DIC Corporation

[0266] (b-7) Zinc oxide: Zinc oxide No. 1 produced by Mitsui Mining & Smelting Co., Ltd.

[0267] (b-8) Antiaging agent 1: Nocrac 6C (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0268] (b-9) Antiaging agent 2: Antage RD (2,2,4-trimethyl-1,2-dihydroquinoline) manufactured by Kawaguchi Chemical Industry Co., Ltd.

[0269] (b-10) Stearic acid: "Tsubaki" stearic acid produced by NOF Corporation

[0270] (b-11) Crosslinking agent, vulcanization accelerator and crosslinking aid

[0271] Sulfur: Powdered sulfur produced by Tsurumi Chemical Co., Ltd.

[0272] Vulcanization accelerator: Noxceler DZ (N,N-dicyclohexyl-2-benzothiazolesulfenamide) produced by Ouchi Shinko Chemical Industry Co., Ltd.

[0273] Cross-linking agent: Duralink HTS produced by Flex

[0274] (2) Production of rubber composition

[0275] According to the formulations shown in Tables 1 and 2, materials other than sulfur and the vulcanization accelerator were kneaded at 150° C. for 5 minutes using a Banbury mixer to obtain a kneaded product. Each compounding amount is parts by mass.

[0276] Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded using an open roll mill at 80° C. for 5 minutes to obtain a rubber composition for belts.

[0277] 2. Tire production

[0278] Double-twisted steel cords with a filament diameter of 0.3 mm were drawn and arranged so that 42 steel cords were arranged every 5 cm. The resulting belt rubber composition was applied to both the upper and lower sides of the steel cords to a total thickness of 0.95 mm. After vulcanization, the steel cords were cut at a 24° angle to the tire circumferential direction to obtain a belt component.

[0279] Thereafter, the two layers of belt components were laminated together with other tire components so as to cross each other to form an unvulcanized tire, and press vulcanization was performed at 170°C for 10 minutes to produce test tires having a size of 175 (Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-5).

[0280] In each test tire, the above (L 80 / L0) is set to 0.5, the total cross-sectional area of ​​the circumferential grooves is set to 22% of the cross-sectional area of ​​the tread portion, and the total volume of the lateral grooves (including the lateral grooves with a groove width / groove depth of 0.65) is set to 3.5% of the volume of the tread portion.

[0281] 3. Parameter calculation

[0282] Then, the outer diameter Dt (mm), cross-sectional width Wt (mm), cross-sectional height Ht (mm), aspect ratio (%), and distance T (mm) from the tread surface to the belt layer of each test tire were obtained, and the virtual volume V (mm) was obtained. 3 At the same time, rubber specimens 40 mm long and 4 mm wide were cut from between the belt layers of each test tire to prepare viscoelasticity measurements. Tan δ and E* were measured for each rubber specimen using an Eplexor series manufactured by GABO Co., Ltd. at 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain of 1%. Tan δ / E* was calculated. The results are shown in Tables 1 and 2.

[0283] Then, calculate (Dt-2×Ht), (Dt 2 ×π / 4) / Wt, (V+1.5×10 7 ) / Wt、(V+2.0×10 7 ) / Wt、(V+2.5×10 7 ) / Wt, [(tan δ / E*) / Wt]×1000, and (tan δ / E*)×T. The results are shown in Tables 1 and 2.

[0284] 4. Performance evaluation test

[0285] (1) Evaluation of handling stability

[0286] Each test tire was mounted on all wheels of a vehicle (a Japanese-made FF car with a displacement of 2000cc). After being inflated to an internal pressure of 250 kPa, the tires were driven on a dry road test course at speeds of 40 km / h and 120 km / h. Drivers then evaluated changes in handling performance due to changes in driving speed using a five-point scale ranging from 1 (noticeable change) to 5 (little change). The total score of the 20 drivers' evaluations was then calculated.

[0287] Then, the results of Comparative Examples 1 to 4 were set as 100, and the results of each test tire were expressed as an index according to the following formula to evaluate the steering stability. A larger value indicates better steering stability.

[0288] Steering stability = [(results of the test tire) / (results of comparative examples 1-4)] × 100

[0289] (2) Evaluation of durability

[0290] Each test tire was mounted on all wheels of a vehicle (a Japanese-made FF car, 2000cc displacement), inflated to an internal pressure of 250 kPa, and driven 10 times at 50 km / h. The vehicle then climbed over uneven surfaces at 80 km / h and repeated the test on a dry surface at the test site while overloaded. The vehicle then circled again at 50 km / h, gradually increasing speed to measure the speed at which the driver noticed something unusual.

[0291] Next, the durability performance was expressed as an index according to the following formula, with the results of Comparative Examples 1 to 5 being 100, for relative evaluation: The larger the index, the better the durability.

[0292] Durability = [(results of test tire) / (results of comparative examples 1-5)] × 100

[0293] (3) Comprehensive evaluation

[0294] The evaluation results of (1) and (2) above are added together to obtain a comprehensive evaluation.

[0295] (4) Evaluation results

[0296] The evaluation results are shown in Tables 1 and 2.

[0297] [Table 1]

[0298]

[0299] [Table 2]

[0300]

[0301] [Experiment 2]

[0302] In this experiment, 195 size tires were prepared and evaluated.

[0303] After producing the test tires of Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-5 shown in Tables 3 and 4 in the same manner as Experiment 1, the various parameters were calculated using the same procedures. Performance evaluation tests were then conducted and evaluated in the same manner. The results of Comparative Example 2-4 were set to 100, and steering stability was evaluated; the results of Comparative Example 2-5 were set to 100, and durability performance was evaluated. The results of each evaluation are shown in Tables 3 and 4.

[0304] [Table 3]

[0305]

[0306] [Table 4]

[0307]

[0308] [Experiment 3]

[0309] In this experiment, 225 size tires were prepared and evaluated.

[0310] After producing the test tires of Examples 3-1 to 3-5 and Comparative Examples 3-1 to 3-5 shown in Tables 5 and 6 in the same manner as Experiment 1, the various parameters were calculated using the same procedures. Performance evaluation tests were then conducted and evaluated in the same manner. The results of Comparative Example 3-4 were set to 100 for evaluating changes in handling stability (handling performance); the results of Comparative Example 3-5 were set to 100 for evaluating durability performance. The results of each evaluation are shown in Tables 5 and 6.

[0311] [Table 5]

[0312]

[0313] [Table 6]

[0314]

[0315] [Summary of Experiments 1 to 3]

[0316] It can be seen from the results of Experiments 1 to 3 (Tables 1 to 6) that for tires of any size (175 size, 195 size, 225 size), the results show that when (tanδ / E*) is greater than or equal to 0.002 and less than or equal to 0.017, and satisfies the above-mentioned (Formula 1) and (Formula 2), a pneumatic tire can be provided whose handling stability is sufficiently improved and whose durability is also sufficiently improved.

[0317] Then, the results show that by satisfying the respective requirements defined in the present disclosure, a tire having further improved handling stability variation and durability performance can be provided.

[0318] On the other hand, when (tanδ / E*) does not satisfy 0.002 or more and 0.017 or less, or does not satisfy either (Formula 1) or (Formula 2), it is found that the change in handling performance between low speed and high speed cannot be sufficiently reduced and durability cannot be sufficiently improved.

[0319] [Experiment 4]

[0320] Next, three tires (Examples 4-1 to 4-3) were produced using the same formulation, each with no significant difference in the relationship between the virtual volume (V) and the cross-section width (Wt), and evaluated in the same manner. The results of Example 4-1 were set as 100 for changes in handling stability (driving performance), and as 100 for durability performance.

[0321] Furthermore, in this test, in addition to the above-mentioned evaluations of the steering stability and the durability performance, the fuel efficiency was also evaluated.

[0322] Specifically, each test tire was mounted on all wheels of a vehicle (a Japanese-made FF car with a displacement of 2000cc). After being inflated to an internal pressure of 250 kPa, the tire was driven at 80 km / h on a dry test course. After completing a 10-kilometer lap, the accelerator was released and the distance from the time the accelerator was released until the vehicle came to a stop was measured as the rolling resistance of each test tire.

[0323] Next, the results for each test tire were expressed as an index using the following formula, with the results for Example 4-3 set to 100. Rolling resistance during high-speed driving was evaluated relative to fuel efficiency. A larger value indicates a longer distance from accelerator release to vehicle stop, lower rolling resistance in steady state, and higher fuel efficiency.

[0324] Fuel efficiency = [(result of test tire) / (result of Example 4-3)] × 100

[0325] (Comprehensive evaluation)

[0326] As in Experiments 1 to 3, the results of each evaluation were added together to obtain a comprehensive evaluation. Table 7 shows the results of each evaluation.

[0327] [Table 7]

[0328]

[0329] Table 7 shows that while the relationship between the virtual volume V and the cross-sectional width Wt does not differ significantly, as the cross-sectional width Wt decreases, for example, from less than 205 mm to less than 200 mm, and as the flatness increases, all of the steering stability, durability, and fuel efficiency improve. In other words, it can be seen that significant effects are exhibited.

[0330] 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 same and equivalent scope as the present disclosure.

[0331] The present disclosure (1) is:

[0332] A pneumatic tire having a belt layer on the radially inner side of a tread portion, wherein:

[0333] The rubber composition constituting the belt layer has a ratio (tanδ / E*) of the loss tangent (tanδ) to the complex elastic modulus (E*: MPa) of 0.002 or more and 0.017 or less, as measured under the conditions of 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%.

[0334] The cross-sectional width of the tire when mounted on a standardized rim and at an internal pressure of 250 kPa is Wt (mm), the outer diameter is Dt (mm), and the volume of the space occupied by the tire is the virtual volume V (mm 3 ), the tire satisfies the following (Formula 1) and (Formula 2):

[0335] 1700 ≤ (Dt 2 ×π / 4) / Wt ≤ 2827.4 (Formula 1)

[0336] [(V+1.5×10 7 ) / Wt]≤2.88×10 5 (Formula 2).

[0337] The present disclosure (2) is a pneumatic tire according to the present disclosure (1), wherein the pneumatic tire satisfies the following (Formula 3):

[0338] [(V+2.0×10 7 ) / Wt]≤2.88×10 5 (Formula 3).

[0339] The present disclosure (3) is a pneumatic tire according to the present disclosure (2), wherein the pneumatic tire satisfies the following (Formula 4):

[0340] [(V+2.5×10 7 ) / Wt]≤2.88×10 5 (Formula 4).

[0341] The present disclosure (4) is a pneumatic tire according to any combination of the present disclosures (1) to (3), wherein, when mounted on a standardized rim and with an internal pressure of 250 kPa, the outer diameter of the tire is set to Dt (mm), the cross-sectional height of the tire is set to Ht (mm), and then (Dt-2×Ht) is 470 (mm) or more.

[0342] The present disclosure (5) is a pneumatic tire according to any combination of the present disclosures (1) to (4), wherein the aspect ratio of the pneumatic tire is 40% or more.

[0343] The present disclosure (6) is a pneumatic tire according to the present disclosure (5), wherein the aspect ratio of the pneumatic tire is 45% or more.

[0344] The present disclosure (7) is a pneumatic tire according to the present disclosure (6), wherein the aspect ratio of the pneumatic tire is 47.5% or more.

[0345] The present disclosure (8) is a pneumatic tire according to the present disclosure (7), wherein the aspect ratio of the pneumatic tire is 50% or more.

[0346] The present disclosure (9) is a pneumatic tire according to any combination of the present disclosures (1) to (8), wherein the ratio of the loss tangent to the complex elastic modulus (tan δ / E*) of the rubber composition constituting the belt layer is 0.009 or less.

[0347] The present disclosure (10) is a pneumatic tire according to any combination of the present disclosures (1) to (9), wherein the pneumatic tire satisfies the following (Formula 5):

[0348] [(tanδ / E*) / Wt]×1000≤0.60 (Equation 5).

[0349] The present disclosure (11) is a pneumatic tire according to the present disclosure (10), wherein the pneumatic tire satisfies the following (Formula 6):

[0350] [(tanδ / E*) / Wt]×1000≤0.55 (Formula 6).

[0351] The present disclosure (12) is a pneumatic tire according to any combination of the present disclosures (1) to (11), wherein the pneumatic tire satisfies the following (Formula 7):

[0352] (tanδ / E*) × T ≤ 1.00 (Equation 7)

[0353] Where T (mm) is the distance from the tread surface to the belt layer.

[0354] The present disclosure (13) is a pneumatic tire according to the present disclosure (12), wherein the pneumatic tire satisfies the following (Formula 8):

[0355] (tanδ / E*)×T≤0.85 (Formula 8).

[0356] The present disclosure (14) is a pneumatic tire according to any combination of the present disclosures (1) to (13), wherein the tread portion has a circumferential groove extending continuously in the tire circumferential direction, and the groove width L at a depth of 80% of the maximum depth of the circumferential groove is 80 The ratio (L 80 / L0) is 0.3 to 0.7.

[0357] The present disclosure (15) is a pneumatic tire according to any combination of the present disclosures (1) to (14), wherein the tread portion 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 10% to 30% of the cross-sectional area of ​​the tread portion.

[0358] The present disclosure (16) is a pneumatic tire according to any combination of the present disclosures (1) to (15), wherein the tread portion has a plurality of lateral grooves extending in the axial direction of the tire, and the total volume of the plurality of lateral grooves accounts for 2.0% to 5.0% of the volume of the tread portion.

[0359] The present disclosure (17) is a pneumatic tire according to any combination of the present disclosures (1) to (16), wherein the outer diameter of the tire when mounted on a standardized rim and at an internal pressure of 250 kPa is set to Dt, and Dt is less than 685 (mm).

[0360] The present disclosure (18) is a pneumatic tire according to any combination of the present disclosures (1) to (17), wherein the cross-sectional width Wt (mm) is less than 205 mm.

[0361] The present disclosure (19) is a pneumatic tire according to the present disclosure (18), wherein the cross-sectional width Wt (mm) is less than 200 mm.

[0362] The present disclosure (20) is a pneumatic tire according to any combination of the present disclosures (1) to (19), wherein the steel cords in the belt layer extend at an angle of 15° or more and 50° or less with respect to the tire circumferential direction.

[0363] The present disclosure (21) is a pneumatic tire according to any combination of the present disclosures (1) to (20), wherein the pneumatic tire is a pneumatic tire for a passenger vehicle.

Claims

1. A pneumatic tire comprising a belt layer on the radially inner side of a tread portion, wherein: The rubber composition constituting the belt layer has a ratio (tanδ / E*) of the loss tangent (tanδ) to the complex elastic modulus (E*: MPa) of 0.002 or more and 0.017 or less, as measured under the conditions of 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%. The cross-sectional width of the tire when mounted on a standardized rim and at an internal pressure of 250 kPa is Wt (mm), the outer diameter is Dt (mm), and the volume of the space occupied by the tire is the virtual volume V (mm 3 ), the tire satisfies the following (Formula 1) and (Formula 2): 1700 ≤ (Dt 2 ×π / 4) / Wt ≤ 2827.4 (Formula 1) [(V+1.5×10 7 ) / Wt]≤2.88×10 5 (Formula 2).

2. The pneumatic tire according to claim 1, wherein The pneumatic tire satisfies the following (Formula 3): [(V+2.0×10 7 ) / Wt]≤2.88×10 5 (Formula 3).

3. The pneumatic tire according to claim 2, wherein: The pneumatic tire satisfies the following (Formula 4): [(V+2.5×10 7 ) / Wt]≤2.88×10 5 (Formula 4).

4. The pneumatic tire according to any one of claims 1 to 3, wherein When mounted on a standardized rim and the internal pressure is 250 kPa, the outer diameter of the tire is Dt (mm) and the cross-sectional height of the tire is Ht (mm). Then (Dt-2×Ht) is 470 (mm) or more.

5. The pneumatic tire according to any one of claims 1 to 4, wherein The pneumatic tire has an aspect ratio of 40% or more.

6. The pneumatic tire according to claim 5, wherein: The pneumatic tire has an aspect ratio of 45% or more.

7. The pneumatic tire according to claim 6, wherein: The pneumatic tire has an aspect ratio of 47.5% or more.

8. The pneumatic tire according to claim 7, wherein: The pneumatic tire has an aspect ratio of 50% or more.

9. The pneumatic tire according to any one of claims 1 to 8, wherein The ratio of the loss tangent to the complex elastic modulus (tan δ / E*) of the rubber composition constituting the belt layer is 0.009 or less.

10. The pneumatic tire according to any one of claims 1 to 9, wherein The pneumatic tire satisfies the following (Formula 5): [(tanδ / E*) / Wt]×1000≤0.60 (Equation 5).

11. The pneumatic tire according to claim 10, wherein: The pneumatic tire satisfies the following (Equation 6): [(tanδ / E*) / Wt]×1000≤0.55 (Formula 6).

12. The pneumatic tire according to any one of claims 1 to 11, wherein The pneumatic tire satisfies the following (Equation 7): (tanδ / E*) × T ≤ 1.00 (Equation 7) Where T (mm) is the distance from the tread surface to the belt layer.

13. The pneumatic tire according to claim 12, wherein: The pneumatic tire satisfies the following (Equation 8): (tanδ / E*)×T≤0.85 (Formula 8).

14. The pneumatic tire according to any one of claims 1 to 13, wherein The tread portion has a circumferential groove extending continuously in the tire circumferential direction, and the groove width L at a depth of 80% of the maximum depth of the circumferential groove is 80 The ratio (L 80 / L0) is 0.3 to 0.

7.

15. The pneumatic tire according to any one of claims 1 to 14, wherein The tread portion has a plurality of circumferential grooves extending continuously in the tire circumferential direction, and a total cross-sectional area of ​​the plurality of circumferential grooves is 10% to 30% of a cross-sectional area of ​​the tread portion.

16. The pneumatic tire according to any one of claims 1 to 15, wherein: The tread portion has a plurality of transverse grooves extending in the tire axial direction, and a total volume of the plurality of transverse grooves accounts for 2.0% to 5.0% of the volume of the tread portion.

17. The pneumatic tire according to any one of claims 1 to 16, wherein: When the outer diameter of a tire mounted on a standardized rim at an internal pressure of 250 kPa is defined as Dt, Dt is less than 685 (mm).

18. The pneumatic tire according to any one of claims 1 to 17, wherein The cross-sectional width Wt (mm) is less than 205 mm.

19. The pneumatic tire according to claim 18, wherein: The cross-sectional width Wt (mm) is less than 200 mm.

20. The pneumatic tire according to any one of claims 1 to 19, wherein The steel cords in the belt layer extend at an angle of 15° or more and 50° or less with respect to the tire circumferential direction.

21. The pneumatic tire according to any one of claims 1 to 20, wherein: The pneumatic tire is a pneumatic tire for passenger vehicles.

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