Pneumatic tire

Abstract

Provided is a pneumatic tire having sufficiently reduced rolling resistance at high speed running and excellent durability. The pneumatic tire has a bead portion, a carcass, and a tread, wherein: a bead reinforcing layer is provided on the tire axial outer side of the carcass, the bead reinforcing layer reinforcing the bead portion from the outer side of the carcass; and the pneumatic tire satisfies the following (Formula 1) and (Formula 2), in which Wt (mm) is the tire cross-sectional width when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, Dt (mm) is the outer diameter, and the imaginary volume V (mm 3 ) is the volume of the space occupied by the tire: 1600 ≤ (Dt 2 × π / 4) / Wt ≤ 2827.4 (Formula 1) [(V + 1.5 x 10 7 ) / Wt] ≤ 2.88 x 10 5 (Formula 2).

Description

Technical Field

[0001] This disclosure relates to an inflatable tire. Background Technology

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

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

[0004] Therefore, in the past, there have been proposals to reduce rolling resistance by designing the formulation of the rubber composition that constitutes the tread of the tire (e.g., Patent Documents 1 to 4).

[0005] Existing technical documents

[0006] Patent documents

[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: JP2 019-206643 A Summary of the Invention

[0011] The problem to be solved by the present invention

[0012] However, tires manufactured using the aforementioned traditional technologies cannot adequately reduce rolling resistance at high speeds and lack sufficient durability.

[0013] Therefore, one object of this disclosure is to provide a pneumatic tire that has sufficiently reduced rolling resistance at high speeds and excellent durability.

[0014] Problem-solving methods

[0015] The authors of this disclosure have diligently researched solutions to the above-mentioned problems and found that these problems can be solved by the following disclosure, thereby completing this disclosure.

[0016] This disclosure is as follows:

[0017] A pneumatic tire has a bead portion, a carcass, and a tread, wherein a bead reinforcement layer is disposed on the axially outer side of the carcass, and the bead reinforcement layer reinforces the bead portion from the outer side of the carcass; and

[0018] Let the cross-sectional width of a tire mounted on a standardized rim with an internal pressure of 250 kPa be Wt (mm), the outer diameter be Dt (mm), and the volume of space occupied by the tire be the hypothetical volume V (mm²). 3 If the tire satisfies the following equations (1) and (2):

[0019] 1600≤(Dt 2 (×π / 4) / Wt≤2827.4 (Equation 1)

[0020] [(V+1.5×10 7 ) / Wt]≤2.88×10 5 (Equation 2).

[0021] Effects of the present invention

[0022] According to this disclosure, a pneumatic tire can be provided that has sufficiently reduced rolling resistance at high speeds and excellent durability. Attached Figure Description

[0023] Figure 1 A schematic cross-sectional view showing the structure near the bead portion in an example of the pneumatic tire of this disclosure.

[0024] Figure 2 A schematic cross-sectional view showing the structure near the bead portion in another example of the pneumatic tire of this disclosure. Detailed Implementation

[0025] [1] Features of the tires disclosed herein

[0026] 1. Overview

[0027] The tire disclosed herein is a pneumatic tire and has the following characteristics.

[0028] First, the tire disclosed herein is characterized in that it is a pneumatic tire having a bead portion, a carcass, and a tread, wherein the bead reinforcement layer is disposed on the axial outer side of the carcass, and the bead reinforcement layer reinforces the bead portion from the outer side of the carcass.

[0029] Furthermore, the tire disclosed herein is characterized in that, when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the tire satisfies the following equations (1) and (2):

[0030] 1600≤(Dt 2 (×π / 4) / Wt≤2827.4 (Equation 1)

[0031] [(V+1.5×10 7 ) / Wt]≤2.88×10 5(Equation 2)

[0032] In the formula, Wt (mm) is the cross-sectional width of the tire, Dt (mm) is the outer diameter, and V (mm) is the cross-sectional width of the tire. 3 ) is the imaginary volume (the volume of space occupied by the tire).

[0033] By providing a tire shape with the above-mentioned characteristics, a tire can be provided that has sufficiently reduced rolling resistance at high speeds and sufficiently excellent durability.

[0034] In the above description, "standardized rim" refers to the rim defined for each tire within a standards system, including the standards upon which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it is the standard rim of applicable dimensions described in the "JATMA Yearbook"; in the case of ETRTO (European Tyre and Rim Technology Organization), it is the "measuring rim" described in the "Standards Manual"; and in the case of TRA (Tire and Rim Association), it is the "design rim" described in the "Yearbook". In the case of tires not specified in the standards, it refers to a rim that can be assembled and maintain internal pressure, i.e., a rim that does not cause air leakage between the rim and the tire and has the minimum rim diameter and the narrowest rim width.

[0035] Furthermore, the tire's outer diameter Dt is the outer diameter of the tire when mounted on a standardized rim with an internal pressure of 250 kPa and under no-load conditions. The tire's cross-sectional width Wt (mm) is the width of the tire when mounted on a standardized rim with an internal pressure of 250 kPa and under no-load conditions, and this width is the distance from the straight-line distance between the sides (the total width of the tire, including all patterns, text, etc. on the tire sidewalls) minus the distance of the patterns, text, etc. on the tire sidewalls.

[0036] Furthermore, specifically, based on the tire's outer diameter Dt (mm), cross-sectional height Ht (mm) (the distance from the bottom of the bead to the outermost surface of the tread; half the difference between the tire's outer diameter and the rim's nominal diameter), and cross-sectional width Wt (mm) when the tire is mounted on a standardized rim with an internal pressure of 250 kPa and no load applied, the imaginary volume V (mm²) of the tire is calculated. 3 It can be calculated using the following formula:

[0037] V = [(Dt / 2)] 2 -{(Dt / 2)-Ht} 2 ]×π×Wt.

[0038] 2. The mechanism of the effect in the tire disclosed herein

[0039] In the tire disclosed herein, the mechanism for significantly reducing rolling resistance at high speeds and exhibiting excellent durability is assumed as follows.

[0040] (1) Tire shape

[0041] As described above, in this disclosure, the cross-sectional width Wt (mm) and outer diameter Dt (mm) of the tire are intended to satisfy:

[0042] 1600≤(Dt 2 ×π / 4) / Wt≤2827.4 (Equation 1).

[0043] By increasing the area of ​​the tire when viewed laterally relative to the tire's cross-sectional width Wt [(Dt / 2)] 2 ×π)=(Dt 2 The formula [×π / 4)], which satisfies the numerical range specified in Equation 1, is believed to reduce repeated deformation per unit time, thereby increasing the time available for heat exchange, improving the heat release characteristics of the sidewalls, and reducing friction between the tread and the road surface. As a result, the rolling resistance of the tire can be reduced (low rolling resistance), and its durability can be improved.

[0044] In (Equation 1), (Dt) 2 The value of ×π / 4) / Wt is preferably 1700 or higher, more preferably 1718 or higher, more preferably 1733 or higher, more preferably 1737 or higher, more preferably 1740 or higher, more preferably 1753 or higher, more preferably 1758 or higher, more preferably 1760 or higher, more preferably 1763 or higher, more preferably 1801 or higher, more preferably 1811 or higher, more preferably 1816 or higher, more preferably 1818 or higher, more preferably 1860 or higher, more preferably 1865 or higher, more preferably 1963.4 or higher, more preferably 2004 or higher, more preferably 2018 or higher, more preferably 2027 or higher, more preferably 2030 or higher, more preferably 2033 or higher, and more preferably 2113 or higher.

[0045] However, due to the significant centrifugal force experienced by this type of tire at high speeds, the sidewalls tend to be pulled by the tread portion (where centrifugal force is particularly strong). Since the sidewalls are fixed to the rim at the bead, the deformation near the bead is greater, potentially leading to bead damage. Furthermore, the centrifugal force causes the tread portion to round out, altering the tread pattern profile, which may not adequately reduce rolling resistance at high speeds. Therefore, further improvements are considered possible.

[0046] Therefore, in this disclosure, the hypothetical volume V (mm²) of the tire is... 3 The cross-sectional width Wt (mm) is intended to satisfy:

[0047] [(V+1.5×10 7 ) / Wt]≤2.88×10 5 (Equation 2).

[0048] In this way, it is believed that by reducing the imaginary volume V of the tire by reducing the cross-sectional width Wt, and by reducing the volume of the tire itself, the rate of outer diameter growth caused by centrifugal force can be reduced, the amount of deformation in the middle and side parts of the bead portion can be reduced, and the rounding of the tread portion can be suppressed.

[0049] [(V+1.5×10 7 The preferred value is 2.84 × 10⁻⁶. 5 The following, and more preferably, is 2.83 × 10 5 The following, and more preferably, is 2.77 × 10⁻⁶. 5 The following, and more preferably, is 2.59 × 10 5 The following, and more preferably 2.55×10 5 The following, and more preferably, is 2.53 × 10 5 The following, and more preferably, is 2.49 × 10 5 The following, and more preferably, is 2.47 × 10⁻⁶. 5 The following, and more preferably, is 2.41 × 10 5 The following, and more preferably 2.25×10 5 The following, and more preferably, is 2.23 × 10⁻⁶. 5 The following, and more preferably 2.20×10 5 The following, and more preferably, is 2.18 × 10⁻⁶. 5 The following, and more preferably, is 2.17 × 10 5 The following, and more preferably 2.15×10 5 the following.

[0050] At this point, a better option is:

[0051] [(V+2.0×10 7 ) / Wt]≤2.88×10 5 (Equation 3);

[0052] Further optimization:

[0053] [(V+2.5×10 7 ) / Wt]≤2.88×10 5 (Equation 4)

[0054] The above [(V+2.0×10 7 The value of ) / Wt] is further optimized to be 2.82×10 5 The following, and more preferably, is 2.80×10 5The following, and more preferably, is 2.78 × 10⁻⁶. 5 The following, and more preferably, is 2.76 × 10⁻⁶. 5 The following, and more preferably, is 2.75 × 10 5 The following, and more preferably, is 2.63 × 10⁻⁶. 5 The following, and more preferably, is 2.46 × 10 5 The following, and more preferably, is 2.45 × 10 5 The following, and more preferably, is 2.44 × 10⁻⁶. 5 The following, and more preferably, is 2.43 × 10⁻⁶. 5 The following, and more preferably, is 2.42 × 10 5 the following.

[0055] In addition, [(V+2.5×10 7 The value of ) / Wt] is further optimized to be 2.84×10 5 The following, and more preferably, is 2.75 × 10⁻⁶. 5 The following, and more preferably, is 2.74 × 10⁻⁶. 5 The following, and more preferably, is 2.71 × 10 5 The following, and more preferably 2.70×10 5 The following, and more preferably, is 2.69 × 10⁻⁶. 5 The following, and more preferably, is 2.68 × 10⁻⁶. 5 The following, and more preferably, is 2.67 × 10⁻⁶. 5 the following.

[0056] (2) Bead reinforcement layer

[0057] In the tire disclosed herein, as described above, a bead reinforcement layer is provided on the axial outer side of the tire carcass, reinforcing the bead portion from the outer side of the tire carcass. By providing this bead reinforcement layer, deformation near the bead portion can be further suppressed, thus improving durability. Furthermore, this suppresses lateral deformation, thus improving rolling resistance at high speeds.

[0058] [2] A more preferred embodiment of the tire disclosed herein

[0059] The tire disclosed herein can achieve better results by adopting the following embodiments.

[0060] 1. Flatness

[0061] The tire disclosed herein is preferably a tire with an aspect ratio of 40% or more, thereby increasing the height of the tire sidewall to suppress local deformation of the tire and thus further improving the tire's durability.

[0062] The aforementioned aspect ratio (%) can be obtained using the tire's section height Ht (mm) and section width Wt (mm) at an internal pressure of 250 kPa through the following formula:

[0063] (Ht / Wt)×100(%).

[0064] The flatness ratio is more preferably 45% or more, further preferably 47.5% or more, further preferably 48% 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, and further preferably 59% or more. There is no specific upper limit, but it is, for example, 100% or less.

[0065] 2. Bead reinforcement layer

[0066] When the bead reinforcement layer is used to reinforce the bead portion, from the perspective of suppressing the heat generation of the bead reinforcement layer, it is preferable that the bead reinforcement layer has a small loss tangent (tanδ). On the other hand, from the perspective of suppressing deformation near the bead portion, it is preferable that the bead reinforcement layer has high rigidity, that is, a large complex modulus of elasticity (E*).

[0067] Therefore, the favorable relationship between the loss tangent (tanδ) and the complex elastic modulus (E*:MPa) of the bead reinforcement layer was studied, and it was found that the ratio (tanδ / E*) of the loss tangent (tanδ) to the complex elastic modulus (E*:MPa) of the bead reinforcement layer, measured under the conditions of a temperature of 70°C, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain rate of 1%, is preferably 0.005 or less. More preferably, (tanδ / E*) is 0.002 or less, and even more preferably 0.001 or less.

[0068] Therefore, it can suppress the heat generation of the bead reinforcement layer during rolling, satisfactorily ensure the rigidity of the bead reinforcement layer, and further suppress the increase in tire outer diameter. It is believed that this can significantly reduce rolling resistance at high speeds and significantly improve durability.

[0069] It should be noted that the aforementioned loss tangent (tanδ) and complex modulus of elasticity (E*) refer to rubber cut radially outward from at least the bottom of the tire groove, preferably at half the depth of the deepest circumferential groove. Specifically, for example, these measurements can be performed using a viscoelasticity measuring device, such as the "Eplexor" (registered trademark) manufactured by GABO.

[0070] In a radial cross-sectional view of the tire, the height of the bead reinforcement layer from below the bead core is preferably less than 45% of the height from below the bead core to the outermost surface of the tread. It has been found that this yields a more noticeable effect.

[0071] Furthermore, the larger the area of ​​the tire sidewall, the greater the heat generated in the sidewall where the bead reinforcement layer is located, and the more likely the tire's durability will deteriorate.

[0072] The discloser believes that, in order to prevent this situation, it is necessary to reduce the heat generation coefficient of the bead reinforcement layer based on the increase in side area, and has studied the relationship between the heat generation correlation index (tanδ / E*) of the bead reinforcement layer and the side area correlation index (V / Wt). The results show that if (tanδ / E*)×(V / Wt)≤400 (Equation 5), side heat generation can be suppressed, further improving durability. [(tanδ / E*)×(V / Wt)] is preferably 368 or less, more preferably 339 or less, and even more preferably 309 or less.

[0073] It was also found that (tanδ / E*)×(V / Wt)≤300 (Equation 6) is more preferred. [(tanδ / E*)×(V / Wt)] is more preferably 272 or less, further preferably 252 or less, further preferably 235 or less, further preferably 223 or less, further preferably 202 or less, and further preferably 184 or less.

[0074] 3. Side

[0075] The tire disclosed herein preferably has a sidewall formed of a rubber composition in the side portion, wherein the loss tangent (tanδ) of the rubber composition, measured under conditions of a temperature of 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%, is 0.08 or less, more preferably 0.06 or less. This suppresses side portion deformation caused by heat generated during driving. As a lower limit, for example, tanδ is preferably 0.02 or more.

[0076] The complex modulus of elasticity (E*: MPa) of the rubber composition, measured under the same conditions, is preferably 4.0 MPa or less, more preferably 3.5 MPa or less. This allows the bead reinforcement layer to support the flexible sidewall, preventing stretching of the sidewalls due to centrifugal force during driving. Furthermore, by exhibiting elasticity upon impact, it can mitigate the impact force and further improve durability. As a lower limit, it is preferably 2.0 MPa or more, for example, more preferably 2.5 MPa or more.

[0077] 4. Overlap section

[0078] In the tire disclosed herein, since the bead reinforcement layer is provided on the outer side of the tire carcass along the tire axial direction, the deformation during rolling becomes a movement centered on the joint with the rim, the degree of deformation at the overlap is greater than before, and the heat generation is also considered to be greater.

[0079] To suppress heat generation at the overlap, the overlap is preferably formed of a rubber composition having a loss angle (tanδ) of 0.10 or less, more preferably 0.08 or less, measured under conditions of 70°C, 10Hz, 5% initial strain, and 1% dynamic strain rate. This reduces heat generation at the overlap and suppresses heat transfer to the tire sidewall (side), thereby improving durability and reducing rolling resistance. Furthermore, as a lower limit, it is preferably 0.03 or more, for example, more preferably 0.04 or more.

[0080] The complex modulus of elasticity (E*: MPa) of the rubber composition, measured under the same conditions, is preferably 8.0 MPa or more, more preferably 9.0 MPa or more. This increases the stiffness of the overlap (where deformation tends to concentrate during rolling), thereby suppressing deformation itself and reducing heat generation. As an upper limit, it is preferably 15.0 MPa or less, for example, more preferably 12 MPa or less.

[0081] 5. Tread grooves

[0082] The tire disclosed herein has circumferential grooves extending continuously in the circumferential direction along the tread. The groove width L is located at 80% of the maximum depth of the circumferential grooves. 80 The ratio of the groove width L0 of the circumferential grooves in the tread contact surface (L) 80 The ratio ( / L0) is preferably 0.3 to 0.7. This suppresses movement of the entire landmass on the bottom surface of the tread portion, thus preventing spalling in the tread portion. More preferably, this ratio is 0.35 to 0.65, further preferably 0.40 to 0.60, and particularly preferably 0.45 to 0.55. The circumferential groove can be a groove extending continuously in the tire circumference, and non-linear grooves (e.g., zigzag grooves and wavy grooves) are also included in the circumferential groove.

[0083] The above L0 and L 80 These refer to the straight-line distance (L0) between the edges of the grooves on the tread surface of the tire's circumferential grooves, respectively, when the tire is mounted on a standardized rim, with an internal pressure of 250 kPa and no load applied, and the minimum distance (L) between the groove walls at a position where the groove depth is 80%. 80 In short, they can be obtained by pressing the bead portion, which has a radially cut cross-section of 2 to 4 cm in width, into a shape that matches the width of the rim.

[0084] Preferably, 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. It is believed that this can suppress tread movement and inhibit tread peeling during high-speed driving. More preferably, it is 15 to 27%, further preferably 18 to 25%, and particularly preferably 21 to 23%.

[0085] The cross-sectional area of ​​circumferential grooves refers to the total area formed by the straight lines connecting the ends of the circumferential grooves and the groove walls in a tire mounted on a standardized rim under an internal pressure of 250 kPa and in a no-load condition. In short, they can be obtained by pressing the bead portion, with a radially cut cross-section of 2 to 4 cm, to the same width as the rim.

[0086] Furthermore, preferably, the tread has a plurality of lateral grooves extending axially along the tire, the total volume of which is 2.0% to 5.0% of the tread volume. This is believed to suppress tread movement, inhibit uneven wear, and improve durability. More preferably, it is 2.2% to 4.0%, further preferably 2.5% to 3.5%, and particularly preferably 2.7% to 3.0%.

[0087] The volume of the aforementioned lateral grooves refers to the total volume of a tire mounted on a standardized rim, with an internal pressure of 250 kPa and under no-load conditions, consisting of the surface connecting the ends of the lateral grooves and the groove walls. In short, it can be obtained by pressing the bead portion, with a radially cut cross-section of 2 to 4 cm width, to the same width as the rim, multiplying the volume of each lateral groove by the number of grooves. Furthermore, the volume of the tread portion can be calculated by multiplying the area of ​​the portion of this cross-section excluding the lateral grooves by the outer diameter, and then obtaining the difference between this calculation and the lateral groove volume.

[0088] To suppress tread stripping and further improve durability, it is preferable that the ratio (Gw / Gd) of the groove width Gw to the groove depth Gd of at least one of these lateral grooves is 0.50 to 0.80. More preferably, this ratio is 0.53 to 0.77, further preferably 0.55 to 0.75, and particularly preferably 0.60 to 0.70.

[0089] The groove width and groove depth of the aforementioned lateral grooves refer to the maximum length (perpendicular to the groove direction) of the straight line connecting the ends of the tread surface of the lateral grooves in a tire under conditions of internal pressure of 250 kPa and no load applied, respectively. In short, it can be calculated by pressing the bead portion, with a radially cut cross-section of 2 to 4 cm in width, to the same width as the rim.

[0090] 6. Tire shape

[0091] 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 649 mm or more, further preferably 658 mm or more, further preferably 663 mm or more, further preferably 64 mm or more, further preferably 665 mm or more, further preferably 672 mm or more, and most preferably 673 mm or more.

[0092] On the other hand, the specific outer diameter Dt (mm) is preferably less than 843 mm, more preferably less than 733 mm, even more preferably less than 725 mm, even more preferably less than 718 mm, even more preferably less than 717 mm, even more preferably less than 716 mm, even more preferably less than 714 mm, even more preferably less than 710 mm, even more preferably less than 707 mm, even more preferably less than 692 mm, even more preferably less than 690 mm, even more preferably less than 685 mm, even more preferably less than 684 mm, even more preferably less than 680 mm, even more preferably less than 679 mm, even more preferably less than 674 mm.

[0093] The specific cross-sectional width Wt (mm) is preferably 115mm or more, more preferably 130mm or more, even more preferably 150mm or more, even more preferably 170mm or more, even more preferably 175mm or more, even more preferably 176mm or more, even more preferably 177mm or more, even more preferably 178mm or more, even more preferably 181mm or more, even more preferably 182mm or more, particularly preferably 185mm or more, and most preferably 193mm or more.

[0094] On the other hand, the specific cross-sectional width Wt (mm) is preferably less than 305mm, more preferably less than 245mm, even more preferably less than 233mm, even more preferably less than 231mm, even more preferably less than 229mm, even more preferably less than 225mm, even more preferably less than 210mm, even more preferably less than 205mm, even more preferably less than 201mm, even more preferably less than 200mm, even more preferably less than 200mm, even more preferably less than 199mm.

[0095] For example, the specific cross-sectional height Ht (mm) is preferably 37mm or more, more preferably 69mm or more, even more preferably 70mm or more, even more preferably 78mm or more, even more preferably 79mm or more, even more preferably 80mm or more, even more preferably 87mm or more, even more preferably 88mm or more, even more preferably 90mm or more, even more preferably 95mm or more, even more preferably 96mm or more, even more preferably 98mm or more, even more preferably 99mm or more.

[0096] On the other hand, the specific cross-sectional height Ht (mm) is preferably less than 180mm, more preferably less than 116mm, even more preferably less than 113mm, even more preferably less than 112mm, even more preferably less than 105mm, even more preferably less than 101mm, and even more preferably less than 101mm.

[0097] The specific hypothetical volume V is preferably 13,000,000 mm². 3 The above, and more preferably, is 23,136,067 mm. 3 The above, and more preferably, are 23, 206, and 160 mm. 3 The above, and more preferably the 23,377,471 mm 3 The above, and more preferably the 28,575,587mm 3 The above, and more preferably the 28,813,525mm 3 The above, and more preferably 29,000,000 mm 3 The above, and more preferably the 29,087,378 mm 3 The above, and more preferably the 29,823,416mm 3 The above, and more preferably the 30, 327, 983 mm 3 The above, and more preferably, are 34,466,507 mm. 3 The above, and more preferably, is 36,000,000 mm 3 The above, and more preferably the 36,015,050mm 3 The above, and more preferably, are 36, 140, and 254 mm. 3 The above, and more preferably, are 36,203,610 mm. 3 The above, and more preferably, are 36, 260, and 445 mm. 3 The above, and more preferably, is 37,040,131 mm. 3 above.

[0098] On the other hand, the hypothetical volume V is preferably less than 66,000,000 mm². 3 A more preferred value is 51,283,296 mm.3 The following is a further preferred size: less than 44,000,000 mm. 3 Further preferred sizes are 43, 478, and 150 mm. 3 The following, and more preferably, are 42,045,141 mm. 3 The following, and more preferably, are 40, 755, and 756 mm. 3 The following, and more preferably, is 38,800,000 mm. 3 the following.

[0099] Furthermore, in the tire disclosed herein, considering the stability of driving comfort during operation, (Dt-2×Ht) is preferably 450 mm or more, more preferably 457 mm or more, even more preferably 458 mm or more, even more preferably 470 mm or more, even more preferably 480 mm or more, even more preferably 482 mm or more, and even more preferably 483 mm or more.

[0100] On the other hand, considering the deformation of the tread, it is preferably less than 560 mm, more preferably less than 559 mm, even more preferably less than 558 mm, even more preferably less than 534 mm, even more preferably less than 533 mm, even more preferably less than 530 mm, even more preferably less than 510 mm, even more preferably less than 508 mm, and even more preferably less than 507 mm.

[0101] [3] Embodiments of this disclosure

[0102] The present disclosure will now be described in detail according to the embodiments.

[0103] 1. Rubber composition forming the bead reinforcement layer

[0104] In this disclosure, the rubber composition forming the bead reinforcement layer can be obtained by suitably adjusting the type and amount of various compounding materials, such as the rubber components, fillers, softeners and vulcanization accelerators described below.

[0105] (1) Rubber components

[0106] In this embodiment, rubber (polymers) commonly used in tire manufacturing are used as the rubber component, such as styrene-butadiene rubber (SBR), isoprene rubber, butadiene rubber (BR), and nitrile rubber (NBR). Among these, isoprene rubber and styrene-butadiene rubber (SBR) are preferred. In these rubbers, the rubber phases can be phase-separated and intertwined, thereby reducing internal strain in the rubber.

[0107] (a) Isoprene-based rubber

[0108] From the perspective of good low heat generation and durability, the content (total content) of isoprene-based rubber in 100 parts by weight of the rubber component is preferably greater than 40 parts by weight, more preferably greater than 60 parts by weight, and even more preferably greater than 65 parts by weight. On the other hand, it is preferably less than 90 parts by weight, more preferably less than 80 parts by weight, even more preferably less than 75 parts by weight, and particularly preferably 70 parts by weight. Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Among these, NR is preferred from the perspective of excellent strength.

[0109] For natural rubber (NR), common materials used in the tire industry include SIR20, RSS#3, and TSR20. Natural rubber (IR) has no particular limitations and can be materials such as IR2200, also commonly used in the tire industry. Modified NR includes deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IR includes epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These can be used individually or in combination.

[0110] (b)SBR

[0111] In 100 parts by weight of rubber component, the content of SBR is preferably greater than 10 parts by weight, more preferably greater than 20 parts by weight, even more preferably greater than 25 parts by weight, and even more preferably greater than 30 parts by weight.

[0112] On the other hand, it is preferably less than 60 parts by mass, more preferably less than 40 parts by mass, and even more preferably less than 35 parts by mass.

[0113] For example, the weight-average molecular weight of the SBR is greater than 100,000 and less than 2 million. The styrene content of the SBR is preferably greater than 5%, more preferably greater than 10%, and even more preferably greater than 20%. 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 (the amount of 1,2-bonded butadiene units) of the SBR is, for example, greater than 5% by mass and less than 70% by mass. The structural identification of the SBR (measuring the styrene content and vinyl bond content) can be performed using instruments such as the JNM-ECA series manufactured by JEOL Corporation.

[0114] There are no particular limitations on SBR; it can use, for example, emulsion-polymerized styrene-butadiene rubber (E-SBR) or solution-polymerized styrene-butadiene rubber (S-SBR). SBR can be unmodified or modified, and these can be used alone or in combination of two or more.

[0115] Modified SBRs can be any SBR having functional groups that interact with fillers (e.g., silica). Examples include: end-modified SBRs where at least one end of the SBR is modified with a compound (modifier) ​​having the aforementioned functional groups (end-modified SBRs with the aforementioned functional groups at the ends); main-chain modified SBRs having functional groups on the main chain; main-chain end-modified SBRs having functional groups on both the main chain and the ends (e.g., main-chain end-modified SBRs having the aforementioned functional groups on the main chain and at least one end modified with the aforementioned modifier); and end-modified SBRs modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and in which epoxy groups or hydroxyl groups are introduced.

[0116] Examples of functional groups include: amino, amide, silyl, alkoxysilyl, isocyanate, imino, imidazo, urea, ether, carbonyl, oxycarbonyl, mercapto, thioether, dithioether, sulfonyl, sulfinyl, thiocarbonyl, ammonium, imide, hydrazine, azo, diazo, carboxyl, nitrile, pyridyl, alkoxy, hydroxyl, oxygen, and epoxy. Furthermore, these functional groups may have substituents.

[0117] Furthermore, as a modified SBR, an SBR modified with, for example, a compound (modifier) ​​represented by the following formula can be used.

[0118] [Chemistry 1]

[0119]

[0120] In the formula, R 1 R 2 and R 3 Same or different, indicating alkyl, alkoxy, siloxy, acetal, carboxyl (-COOH), mercapto (-SH) or their derivatives. R 4 and R 5 Same or different, indicating hydrogen atoms or alkyl groups. R 4 and R 5 It can combine with nitrogen atoms to form a ring structure. n represents an integer.

[0121] As an SBR modified by the compound (modifier) ​​represented by the above formula, an SBR whose polymerization end (active end) of solution polymerized styrene-butadiene rubber (S-SBR) is modified by the compound represented by the above formula (e.g., the modified SBR described in JP-A-2010-111753).

[0122] As R 1 R 2 and R 3 Alkoxy groups (preferably alkoxy groups having 1 to 8 carbon atoms, more preferably alkoxy groups having 1 to 4 carbon atoms) are suitable. As R4 and R 5 Alkyl groups (preferably alkyl groups having 1 to 3 carbon atoms) are suitable. n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. Furthermore, when R... 4 and R 5 When the bond combines with a nitrogen atom to form a ring structure, a 4- to 8-membered ring is preferred. Alkoxy groups also include cycloalkoxy groups (such as cyclohexyloxy) and aryloxy groups (such as phenoxy and benzyloxy).

[0123] Specific examples of the aforementioned 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.

[0124] In addition, modified SBRs can also be used as modified SBRs by the following compounds (modifiers). Examples of modifiers include:

[0125] Polyhydric alcohol polyglycidyl ethers, such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolethane triglycidyl ether and trimethylolpropane triglycidyl ether;

[0126] Polyglycidyl ethers of aromatic compounds having two or more phenolic groups, such as diglycidylated bisphenol A;

[0127] Polyepoxides, such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene and polyepoxide liquid polybutadiene;

[0128] Tertiary amines containing epoxy groups, such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine;

[0129] Diglycidylamino compounds, such as diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl-o-toluidine, tetraglycidyl-m-xylyldiamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-diaminomethylcyclohexane;

[0130] Amino-containing acyl chlorides, such as bis-(1-methylpropyl)carbamoyl chloride, 4-morpholine carbamoyl chloride, 1-pyrrolidine carbamoyl chloride, N,N-dimethylcarbamoyl chloride and N,N-diethylcarbamoyl chloride;

[0131] Silane compounds containing epoxy groups, such as 1,3-bis-(glycidoxypropyl)-tetramethyldisiloxane and (3-glycidoxypropyl)-pentamethyldisiloxane;

[0132] Silane compounds containing thioether groups, such as (trimethylsilyl)[3-(trimethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(tripropoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldipropoxysilyl)propyl] sulfide, and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide;

[0133] N-substituted aziridine compounds, such as ethyleneimine and propyleneimine;

[0134] Alkoxysilanes, such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane;

[0135] (Thio)benzophenone compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-tert-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone and N,N,N',N'-bis-(tetraethylamino)benzophenone;

[0136] Benzaldehyde compounds having an amino group and / or substituted amino groups, such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde and 4-N,N-divinylaminobenzaldehyde;

[0137] N-substituted pyrrolidones, such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone and N-methyl-5-methyl-2-pyrrolidone;

[0138] N-substituted piperidinones, such as N-methyl-2-piperidinone, N-vinyl-2-piperidinone and N-phenyl-2-piperidinone;

[0139] N-substituted lactams, such as 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;

[0140] N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-trione, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethylurea, 1,3-divinylethylurea, 1,3-diethyl-2-imidazolinone, 1-methyl-3-ethyl-2-imidazolinone, 4-N,N-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, and 1,7-bis(methylethylamino)-4-heptanone.

[0141] Modification using the above-mentioned compounds (modifiers) can be carried out by known methods.

[0142] As an SBR (Self-Borne Blast Reactor), SBRs manufactured and sold by companies such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation can be used. SBRs can be used alone or in combination of two or more types.

[0143] (c) Other rubber components

[0144] In addition, as another rubber component, the rubber composition may contain rubber (polymers) commonly used in the production of tires, such as butadiene rubber (BR) and nitrile rubber (NBR).

[0145] (2) Compound materials other than rubber components

[0146] (a) Packing

[0147] In this embodiment, the rubber composition preferably contains fillers. Specific examples of fillers include carbon black, graphite, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. Among these, carbon black is preferably used as a reinforcing agent. If necessary, silica is also preferably used as a reinforcing agent. In this case, silica is preferably used in conjunction with a silane coupling agent.

[0148] (a-1) Carbon black

[0149] The rubber composition preferably contains carbon black. For example, the carbon black content is preferably 10 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 55 parts by mass or more, relative to 100 parts by mass of the rubber component. On the other hand, it is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less.

[0150] There are no particular limitations on carbon black, but examples include: furnace black (such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF); acetylene black; pyrolysis black (such as FT and MT); and channel black (such as EPC, MPC, and CC). These can be used alone or in combination of two or more.

[0151] For example, the nitrogen adsorption specific surface area (N2SA) of carbon black is 30 m². 2 / g or more and 250m 2 / g or less. For example, the amount of dibutyl phthalate (DBP) absorbed by carbon black is more than 50 ml / 100g and less than 250 ml / 100g. 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.

[0152] There are no specific restrictions on the type of carbon black used; examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include those from companies such as Asahi Carbon Co., Ltd., Cabot Japan Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Shin-Nippon Chemical Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These can be used alone or in combination of two or more.

[0153] (a-2)Silica

[0154] If necessary, the rubber composition preferably also contains silica. From the perspective of obtaining good durability, the BET specific surface area of ​​silica is preferably greater than 140 m². 2 / g, more preferably greater than 160m 2 / g. On the other hand, from the perspective of obtaining good rolling resistance at high speeds, it is preferably less than 250m. 2 / g, more preferably less than 220m 2 / g. Furthermore, relative to 100 parts by weight of the rubber component, the silica content is preferably 5 parts by weight or more, more preferably 15 parts by weight or more, and even more preferably 25 parts by weight or more. On the other hand, it is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, and even more preferably 30 parts by weight or less. The above-mentioned BET specific surface area is the N2SA value measured by the BET method according to ASTM D3037-93.

[0155] Examples of silica include dry silica (anhydrous silica) and wet silica (hydrated silica). Of these, wet silica is preferred because it has a large number of silanol groups.

[0156] Products from companies such as Degussa, Rhodia, Tosoh Silicon Co., Ltd., Solvay Ltd., and Tokuyama Co., Ltd. can be used as silica.

[0157] (a-3) Silane coupling agent

[0158] As mentioned above, when using silica, it is preferable to use a silane coupling agent in conjunction with silica. There are no particular limitations on the silane coupling agent. Examples of silane coupling agents include:

[0159] 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, and bis(2-triethoxysilylethyl)tetrasulfide. 3-Trimethoxysilylpropyl 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 methacrylate monosulfide;

[0160] Mercaptosilane coupling agents, such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, NXT and NXT-Z (both are available from Momentive);

[0161] Vinyl silane coupling agents, such as vinyltriethoxysilane and vinyltrimethoxysilane; amino silane coupling agents, such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane;

[0162] Epoxypropoxysilane coupling agents, such as γ-epoxypropoxypropyltriethoxysilane and γ-epoxypropoxypropyltrimethoxysilane;

[0163] Nitrosilane coupling agents, such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and

[0164] Chlorinated silane coupling agents, such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane.

[0165] These can be used individually or in combination of two or more.

[0166] Products from companies such as Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industries, Azumax, and Toray Corning are used as silane coupling agents.

[0167] For example, the content of silane coupling agent is greater than 3 parts by mass and less than 25 parts by mass relative to 100 parts by mass of silicon dioxide.

[0168] (a-4) Other fillers

[0169] In addition to carbon black and silica, the rubber composition may also contain fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. For example, these contents are greater than 0.1 parts by weight and less than 200 parts by weight relative to 100 parts by weight of the rubber component.

[0170] (b) Resin Components

[0171] (b-1) Curable resin components

[0172] From the perspective of ensuring the rigidity of the bead reinforcement layer, the rubber composition preferably includes a curable resin component. For example, relative to 100 parts by weight of the rubber component, the content of the resin component is preferably 4 parts by weight or more, more preferably 6 parts by weight or more, even more preferably 8 parts by weight or more, even more preferably 12 parts by weight or more, and even more preferably 17 parts by weight or more. On the other hand, it is preferably 30 parts by weight or less, more preferably 20 parts by weight or less.

[0173] Examples of curable resin components include modified resorcinol resins and modified phenolic resins. Specific examples of modified resorcinol resins include Sumikanol 620 (modified resorcinol resin) manufactured by Taoka Chemical Co., Ltd. Examples of modified phenolic resins include PR12686 (cashew oil modified phenolic resin) manufactured by Sumitomo Bakelite Co., Ltd.

[0174] When using modified resorcinol resin, it is preferable to include a methylene donor as a curing agent, if necessary. Examples of methylene donors include hexamethylenetetramine (HMT), hexamethoxymethyl melamine (HMMM), and hexamethylol melamine pentamethyl ether (HMMPME). For example, it is preferable to contain about 5 parts by weight and less than 15 parts by weight of methylene donor relative to 100 parts by weight of the curable resin component.

[0175] As a specific methylene donor, Sumikanol 507, manufactured by Taoka Chemical Co., Ltd., can be used, for example.

[0176] (b-1) Resin Components

[0177] From a processability (tackiness) perspective, the rubber composition preferably includes a resin component, if necessary. The resin component can be solid or liquid at room temperature, and specific examples of resin components include styrene resins, coumarone resins, terpene resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins. Two or more resin components can be used in combination. The content of the resin component relative to 100 parts by weight of the rubber composition is preferably greater than 2 parts by weight and less than 45 parts by weight, more preferably less than 30 parts by weight.

[0178] Styrene resins are polymers that use styrene monomers as constituent monomers. Examples include polymers obtained by polymerizing styrene monomers as a major component (more than 50% by mass). Specifically, it includes homopolymers obtained by polymerizing styrene monomers alone (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 that can be copolymerized with styrene monomers.

[0179] Examples of other monomers include: acrylonitriles, such as acrylonitrile and methacrylates; 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; alkenes, such as 1-butene and 1-pentene; and α,β-unsaturated carboxylic acids, such as maleic anhydride and its anhydrides.

[0180] Coumarin-indene resins are preferred as coumarone-based resins. Coumarin-indene resins are resins containing coumarone and indene as monomeric components constituting the resin backbone (main chain). Examples of monomeric components other than coumarone and indene included in the backbone include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0181] For example, the content of coumarone-indene resin is greater than 1.0 part by weight and less than 50.0 parts by weight relative to 100 parts by weight of rubber component.

[0182] For example, the hydroxyl value (OH value) of coumarone-indene resin is greater than 15 mg KOH / g and less than 150 mg KOH / g. The OH value is the amount of potassium hydroxide required to neutralize the acetic acid bound to the hydroxyl group when 1 g of resin is acetylated, and is expressed in mg. It is a value measured by potentiometric titration (JIS K 0070:1992).

[0183] 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 the ball drops when the softening point is measured using a ring-ball softening point measuring device as defined in JIS K 6220-1:2001.

[0184] Examples of terpene resins include polyterpenes, terpene phenols, and aromatic modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenation products. Terpene compounds refer to those with a composition consisting of (C5H8). n The term represents a hydrocarbon or its oxygen-containing derivative, which is a compound with a terpene as its basic skeleton. Terpenes can be classified as monoterpenes (C6N). 10 H 16 ), sesquiterpenes (C 15 H 24 ) or diterpenes (C 20 H 32 Examples include α-pinene, β-pinene, dipentene, limonene, myrcene, allocirrhene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0185] Examples of polyterpenes include terpene resins made from the aforementioned terpene compounds, such as α-pinene resins, β-pinene resins, limonene resins, dipentene resins, and β-pinene / limonene resins, as well as hydrogenated terpene resins obtained by hydrogenating terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the aforementioned terpene compounds and phenolic compounds, and resins obtained by hydrogenating the aforementioned resins. Specifically, resins obtained by condensing the aforementioned terpene compounds, phenolic compounds, and formalin may 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 aforementioned resins. There are no particular limitations on aromatic compounds (as long as they are compounds with an aromatic ring), 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; and coumarone and indene.

[0186] C5 resin refers to resin obtained by polymerizing C5 fractions. 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-based petroleum resin.

[0187] C9 resin refers to a resin obtained by polymerizing a C9 fraction, which may be hydrogenated or modified. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. As specific examples, coumarone-indene resin, coumarone resin, indene resin, and aromatic vinyl resins are preferred. As aromatic vinyl resins, homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene, are preferred because they are economical, easy to process, and have excellent exothermic properties. Copolymers of α-methylstyrene and styrene are more preferred. As aromatic vinyl resins, those available from companies such as Clayton Corporation and Eastman Chemical Company can be used.

[0188] C5C9 resin refers to a resin obtained by copolymerizing C5 and C9 fractions, which can be hydrogenated or modified. Examples of C5 and C9 fractions include the aforementioned petroleum fractions. C5C9 resins can be those purchased from, for example, Tosoh Corporation, LUHUA, etc.

[0189] There are no particular restrictions on acrylic resins, but solvent-free acrylic resins, for example, can be used.

[0190] As solvent-free acrylic resins, examples include (meth)acrylic resins (polymers) synthesized by high-temperature continuous polymerization (high-temperature continuous bulk polymerization: US4414370B, JP 84-6207A, JP 93-58805B, JP 89-313522A, US 5010166B, Toa Synthetic Research Annual Report TREND2000 Volume 3, pp. 42-45, etc.), thereby minimizing the use of polymerization initiators, chain transfer agents, organic solvents, etc., as auxiliary materials. In this disclosure, (meth)acrylic acid refers to methacrylic acid and acrylic acid.

[0191] Examples of monomeric components constituting acrylic resins 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.

[0192] In addition, aromatic vinyl compounds (such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinylnaphthalene, etc.) and (meth)acrylic acid or (meth)acrylic acid derivatives can be used as monomer components constituting acrylic resins.

[0193] Acrylic resins can be resins composed solely of (meth)acrylic acid components, or resins that also contain components other than (meth)acrylic acid components. Furthermore, acrylic resins can contain hydroxyl, carboxyl, silanol, and other groups.

[0194] As resin components, products from companies such as Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Co., Ltd., Rugers Chemical Co., Ltd., BASF Ltd., Arizona Chemical Co., Ltd., Nitto Chemical Co., Ltd., Nippon Catalyst Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., and Taoka Chemical Co., Ltd. can be used.

[0195] (c) Softener

[0196] The rubber composition may contain oil (including extender oil), liquid rubber, etc., as a softener. The total content of the softener is preferably greater than 1 part by weight, more preferably 2 parts by weight or more, and less than 10 parts by weight, relative to 100 parts by weight of the rubber component. The oil content also includes the amount of oil contained in the rubber (oil-extended rubber).

[0197] Examples of oils include mineral oils (often referred to as processing oils), vegetable oils, or mixtures thereof. Mineral oils (processing oils) can include, for example, paraffinic processing oils, aromatic processing oils, naphthenic processing oils, etc. Examples of vegetable oils include: castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia oil, and tung oil. These can be used alone or in combination of two or more.

[0198] Specific examples of processing oils (mineral oils) include products from Idemitsu Kosan Co., Ltd., Sankyo Oil & Chemical Co., Ltd., Nippon Oil Energy Co., Ltd., Orison Corporation, H&R Ltd., Toyokuni Oil Co., Ltd., Showa Shell Oil Co., Ltd., and Fuji Kosan Co., Ltd.

[0199] Liquid rubber, as mentioned as a softener, is a polymer that is liquid at room temperature (25°C) and has monomers similar to those in solid rubber as constituent elements. Examples of liquid rubber include farnesene polymers, liquid diene polymers, and their hydrogenated additives.

[0200] Farnesene polymers are polymers obtained by polymerizing farnesenes and have farnesene-based structural units. Farnesenes include isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecathetene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecathetene).

[0201] Farnesene polymers can be homopolymers of farnesene (farnesene homopolymers) or copolymers of farnesene and vinyl monomers (farnesene-vinyl monomer copolymers).

[0202] Examples of liquid diene polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene-isoprene copolymer (liquid SIR).

[0203] For example, the weight-average molecular weight (Mw) of polystyrene converted from liquid diene polymers by gel permeation chromatography (GPC) is greater than 1.0 × 10⁻⁶. 3 And less than 2.0 × 10 5 In this specification, the Mw of the liquid diene polymer is a polystyrene equivalent value determined by gel permeation chromatography (GPC).

[0204] For example, relative to 100 parts by mass of rubber component, the content of liquid rubber (total content of liquid farnesene polymer, liquid diene polymer, etc.) is greater than 1 part by mass and less than 100 parts by mass.

[0205] As a liquid rubber, products such as those from Kuraray Corporation and Clay Valley Ltd. can be used.

[0206] (d) Anti-aging agents

[0207] The rubber composition preferably contains an anti-aging agent. The content of the anti-aging agent relative to 100 parts by weight of the rubber component is, for example, more than 1 part by weight, more than 2.5 parts by weight, and less than 10 parts by weight.

[0208] Examples of anti-aging agents include: naphthylamine-based anti-aging agents, such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents, such as octyl 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 styrylphenol; and bisphenol-based, triphenol-based, or polyphenol-based anti-aging agents, such as tetra[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. These can be used alone or in combination of two or more.

[0209] As an anti-aging agent, products from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Co., Ltd., and Flex Inc. can be used.

[0210] (e) Stearic acid

[0211] The rubber composition may contain stearic acid. The stearic acid content relative to 100 parts by weight of the rubber component is, for example, greater than 0.5 parts by weight, greater than 1.5 parts by weight, and less than 10.0 parts by weight. Commonly known stearic acids can be used, such as those from Nippon Oil Co., Ltd., NOF Co., Ltd., Kao Corporation, Fujifilm, and Koh Genuine Chemicals Co., Ltd., and Chiba Fatty Acid Co., Ltd.

[0212] (f) Zinc oxide

[0213] The rubber composition may contain zinc oxide. The zinc oxide content, relative to 100 parts by weight of the rubber component, is, for example, greater than 0.5 parts by weight, more than 6 parts by weight, and less than 10 parts by weight. Conventionally known zinc oxides may be used, such as products from Mitsui Metal Mining Co., Ltd., Toho Co., Ltd., Hakusui Technology Co., Ltd., Seido Chemical Industry Co., Ltd., and Sakai Chemical Co., Ltd.

[0214] (g) Crosslinking agents and vulcanization accelerators

[0215] The rubber composition preferably contains a crosslinking agent (e.g., sulfur). The content of the crosslinking agent relative to 100 parts by weight of the rubber component is, for example, greater than 0.1 parts by weight, more than 2.8 parts by weight, and less than 10.0 parts by weight.

[0216] As sulfur, powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, and soluble sulfur commonly used in the rubber industry can be used. These can be used alone or in combination of two or more.

[0217] As sulfur, products from companies such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flex Industries, Nippon Inkyu Corporation, and Hosoi Chemical Industry Co., Ltd. can be used.

[0218] Examples of crosslinking agents other than sulfur include: sulfur-containing vulcanizing agents, such as Tackirol V200 manufactured by Taoka Chemical Co., Ltd., DURALINK HTS (sodium 1,6-hexamethylene dithiosulfate dihydrate) manufactured by Flex, and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyl dithiohexane)) manufactured by Lanxess; and organic peroxides, such as dicumyl peroxide.

[0219] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator relative to 100 parts by weight of the rubber component is, for example, greater than 0.3 parts by weight, more than 2.8 parts by weight, more than 3.2 parts by weight, more than 3.5 parts by weight, and less than 10.0 parts by weight.

[0220] Examples of vulcanization accelerators include:

[0221] Thiazole-based sulfidation accelerators, such as 2-mercaptobenzothiazole, di-2-benzothiazole disulfide, and N-cyclohexyl-2-benzothiazole sulfenamide;

[0222] Thiuram-based vulcanization accelerators, such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetra(2-ethylhexyl)thiuram disulfide (TOT-N);

[0223] Sulphamides are vulcanization accelerators, such as N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, N-ethoxy-2-benzothiazole sulfenamide, N-ethoxy-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and

[0224] Guanidine-based sulfurization accelerators, such as diphenylguanidine, di-o-tolylguanidine, and o-tolylbiguanidine.

[0225] These can be used individually or in combination of two or more.

[0226] (h) Other

[0227] In addition to the components described above, the rubber composition may also contain additives commonly used in the tire industry, such as metal salts of fatty acids, metal salts of carboxylic acids, and organic peroxides. The content of these additives relative to 100 parts by weight of the rubber component is, for example, greater than 0.1 parts by weight and less than 200 parts by weight.

[0228] (2) Production of rubber compositions for bead reinforcement

[0229] The rubber composition is produced by conventional methods, such as production methods that include a basic kneading step (kneading the rubber components and fillers such as carbon black) and a final kneading step (kneading the kneaded product obtained from the basic kneading step and the crosslinking agent).

[0230] Kneading can be performed using known (sealed) kneading machines (such as Banbury internal mixers, kneaders, or open rolling mills).

[0231] In the basic kneading step, the kneading temperature is, for example, above 50°C and below 200°C, and the kneading time is, for example, above 30 seconds and below 30 minutes. In addition to the above components, in addition to the kneading process, commonly used compounding agents in the rubber industry, such as softeners (e.g., oils), stearic acid, zinc oxide, anti-aging agents, waxes, and vulcanization accelerators, may be added as needed and kneaded.

[0232] In the final kneading step, the kneading product obtained in the basic kneading step and the crosslinking agent are kneaded together. The kneading temperature in the final kneading step is, for example, above room temperature and below 80°C, and the kneading time is, for example, above 1 minute and below 15 minutes. In addition to the above components, in the final kneading step, vulcanization accelerators, zinc oxide, etc., may be added as needed, and kneading is then performed.

[0233] 3. Tire manufacturing

[0234] The tire disclosed herein is manufactured using a conventional method with an uncured rubber composition obtained through a final kneading step. That is, the uncured tire is produced by molding the bead reinforcement layer obtained by extruding the uncured rubber composition into a predetermined shape together with other tire components on a tire forming machine using a conventional method.

[0235] Specifically, on a forming roller, the inner liner (as a component ensuring tire airtightness), the carcass (as a component that bears the load, impact, and inflation pressure received by the tire), and the belt (as a component that strongly tightens the carcass to increase tread rigidity) are wound. The two ends of the carcass are fixed to the side edges, and the bead portion (as a component that fixes the tire to the rim) is arranged and formed into a ring. Then, the tread is glued to the center of the outer periphery, and the bead reinforcement, overlap, and sidewalls (as components that protect the carcass and resist bending) are glued to the radially outer side to produce an uncured tire.

[0236] In this embodiment, it is preferable to provide an inclined belt layer extending at an angle of 15° to 30° relative to the tire circumference as the belt. This ensures tire durability while maintaining sufficient tread rigidity. Furthermore, since it can be constrained circumferentially, it becomes easier to suppress the growth of the outer diameter.

[0237] The uncured tires are then heated and pressurized in a vulcanizing machine to obtain the final tire. The vulcanization step can be performed using known vulcanization methods. The vulcanization temperature is, for example, above 120°C and below 200°C, and the vulcanization time is, for example, above 5 minutes and below 15 minutes.

[0238] Figure 1 and Figure 2 An example of the structure near the bead portion of the resulting tire is shown. Figure 1 and Figure 2 In this diagram, 1 is the bead reinforcement layer, 3 is the sidewall, 4 is the overlap, 5 is the carcass, 6 is the inner liner, 21 is the bead triangle, and 22 is the bead core. The bead is formed by these components. Figure 1 In the middle, the bead reinforcement layer 1 is covered by the overlap portion 4; in Figure 2 In the middle, the bead reinforcement layer 1 extends to a height higher than the overlap portion 4.

[0239] At this time, when the tire is mounted on a standardized rim and the internal pressure is set to 250 kPa, the tire forms a shape that satisfies the above (Equation 1) and (Equation 2).

[0240] The specific tires that can meet the above (Equation 1) and (Equation 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, etc.

[0241] In embodiments of the present invention, tires that can satisfy (Formula 1) and (Formula 2) are preferably applied to pneumatic tires for passenger cars. Satisfying the above formulas can more advantageously solve the problems in this disclosure (i.e., provide a pneumatic tire with sufficiently reduced rolling resistance at high speeds and excellent durability).

[0242] Example

[0243] The present disclosure will now be described in more detail with reference to embodiments.

[0244] [Experiment 1]

[0245] In this experiment, a 175-sized tire was prepared and evaluated.

[0246] 1. Production of rubber compositions for tire bead reinforcement layers

[0247] First, a rubber composition is produced for use in the bead reinforcement layer.

[0248] (1) Compound materials

[0249] First, prepare the following compounding materials.

[0250] (a) Rubber components

[0251] (a-1)NR:TSR20

[0252] (a-2)SBR: Nipol 1502 manufactured by Zeon Corporation of Japan.

[0253] (b) Compounds other than rubber components

[0254] (b-1) Carbon black: Show Black N330 manufactured by Cabot Japan Co., Ltd.

[0255] (b-2) Resin component 1: Sumilite Resin PR12686 (cashew oil modified phenolic resin) manufactured by Sumitomo Bakelite Co., Ltd.

[0256] (b-3) Resin component 2: Sumikanol 620 (modified resorcinol / formaldehyde resin) manufactured by Taoka Chemical Co., Ltd.

[0257] (b-4) Oil: Process X-140 manufactured by Nippon Energy Corporation.

[0258] (b-5) Anti-aging agent 1: Nocrac 6C (N-phenyl N'-(1,3-dimethylbutyl)-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0259] (b-6) Anti-aging agent 2: Nocrac RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline) manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0260] (b-7) Stearic acid: Tsubaki stearic acid manufactured by Nippon Oil Co., Ltd.

[0261] (b-8) Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Metals Mining Co., Ltd.

[0262] (b-9) Crosslinking agents and vulcanization accelerators

[0263] Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

[0264] Vulcanization accelerator 1: Suncellar NS-G (N-tert-butyl-2-benzothiazole sulfenamide) manufactured by Sanshin Chemical Industry Co., Ltd.

[0265] Vulcanization accelerator 2: Suncellar HT(HMT) (hexamethylenetetramine) manufactured by Sanshin Chemical Industry Co., Ltd.

[0266] (2) Manufacturing of rubber compositions for bead reinforcement

[0267] According to the formulations shown in Tables 1 and 2, the materials, excluding sulfur and vulcanization accelerator, were kneaded for 5 minutes at 150°C using a Banbury internal mixer to obtain the kneaded products. The amounts of each compound are parts by weight.

[0268] 2. Tire manufacturing

[0269] Next, sulfur and a vulcanization accelerator were added to the resulting kneaded product, and the mixture was kneaded for 5 minutes at 80°C using an open-roll mill to obtain a rubber composition for the bead reinforcement layer. The resulting tread rubber composition was used to form the bead reinforcement layer, which was then bonded to other tire components to form an unvulcanized tire. This unvulcanized tire was then vulcanized at 170°C for 10 minutes to produce test tires with a 175 size (Examples 1-1 to 1-5 and Comparative Examples 1-3 to 1-5). Meanwhile, the test tires of Comparative Examples 1-1 and 1-2 were produced without a bead reinforcement layer.

[0270] In the tire components, the sidewall is composed of 50 parts by weight of NR (TSR20), 50 parts by weight of BR (UBEPOL BR150B manufactured by Ube Industries, Ltd.), 30 parts by weight of carbon black (Show Black N550 manufactured by Cabot Japan Ltd.), 15 parts by weight of oil (Process X-140 manufactured by Nippon Energy Corporation), 1.5 parts by weight of stearic acid (Tsubaki stearic acid manufactured by Nippon Oil Co., Ltd.), 2.5 parts by weight of zinc oxide (Zinc White No. 1 manufactured by Mitsui Metals & Minerals Co., Ltd.), 2.0 parts by weight of wax (Sannok wax manufactured by Ouchi New Chemical Industry Co., Ltd.), 2.0 parts by weight of anti-aging agent 1 (Nocrac 6C manufactured by Ouchi New Chemical Industry Co., Ltd.), and 2.0 parts by weight of antioxidant 2 (Antage manufactured by Kawaguchi Chemical Industry Co., Ltd.) as compounding materials. The mixture consists of 1.5 parts by weight of sulfur (powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.) and 1.5 parts by weight of vulcanization accelerator (NoccelerNS manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.), which are kneaded together to form a rubber composition and then molded into a predetermined shape.

[0271] In the tire components, the bonding section consists of 50 parts by weight of NR (TSR20), 50 parts by weight of BR (UBEPOL BR150B manufactured by Ube Industries, Ltd.), 60 parts by weight of carbon black (Showblack N550 manufactured by Cabot Japan Ltd.), 5 parts by weight of oil (Process X-140 manufactured by Nippon Energy Corporation), 1.5 parts by weight of stearic acid (Tsubaki stearic acid manufactured by Nippon Oil Co., Ltd.), 3.5 parts by weight of zinc oxide (Zinc White No. 1 manufactured by Mitsui Metals & Minerals Co., Ltd.), 2.0 parts by weight of wax (Sannok wax manufactured by Ouchi New Chemical Industry Co., Ltd.), 2.0 parts by weight of anti-aging agent 1 (Nocrac6C manufactured by Ouchi New Chemical Industry Co., Ltd.), and 2.0 parts by weight of antioxidant 2 (Antage manufactured by Kawaguchi Chemical Industry Co., Ltd.) as compounding materials. The mixture consists of 2.3 parts by weight of sulfur (powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.) and 3.0 parts by weight of vulcanization accelerator (Nocceler NS manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.), which are kneaded together to form a rubber composition and then molded into a predetermined shape.

[0272] 3. Parameter Calculation

[0273] Subsequently, for each test tire, the outer diameter Dt (mm), cross-sectional width Wt (mm), cross-sectional height Ht (mm), and aspect ratio (%) were obtained, and the hypothetical volume V (mm²) was calculated. 3 ).

[0274] In addition, rubber specimens for measuring viscoelasticity were cut from the bead reinforcement layers of each test tire of Examples 1-1 to 1-5 and Comparative Examples 1-3 to 1-5. For each rubber specimen, tanδ and E* were measured using GABO's Eplexor series at a temperature of 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%. When the bead reinforcement layers of the test tires had the same composition, the average value of each measurement was taken.

[0275] At this point, rubber test pieces for measuring viscoelasticity were also cut from the tire sidewall and the overlap, and tanδ and E* were measured under the same conditions. The results were as follows: tanδ of the tire sidewall was 0.06, and E* was 3.1 MPa; tanδ of the overlap was 0.08, and E* was 10.5 MPa.

[0276] Then, we obtain (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, (tanδ / E*) and (tanδ / E*)×(V / Wt). The results are shown in Tables 1 and 2.

[0277] 4. Performance evaluation test

[0278] (1) Evaluation of rolling resistance at high speed

[0279] All test tires were installed on all wheels of the vehicle (a Japanese-made FF car with a 2000cc engine), inflated to an internal pressure of 250 kPa, and then driven at 100 km / h on a dry road test track. After completing one lap (10 km), the accelerator was released, and the distance from when the accelerator was turned off to when the vehicle came to a stop was measured as the rolling resistance at high speed.

[0280] Next, the results of Comparative Examples 1-5 were set to 100, and the results were expressed as an exponent according to the following formula to relatively evaluate the rolling resistance at high speeds. The larger the value, the longer the distance from when the throttle is turned off to when the vehicle stops, the smaller the rolling resistance in a steady state, and the better the fuel efficiency.

[0281] Rolling resistance = [(Results of the test tires) / (Results of Comparative Examples 1-7)] × 100

[0282] (2) Evaluation of durability performance

[0283] The test tires were installed on all wheels of the vehicle (a Japanese-made FF car with a 2000cc engine), inflated to an internal pressure of 250 kPa, and driven 10 times at 50 km / h. Then, the vehicle was driven at 80 km / h up an uneven section of the road surface, and the test was repeated on a dry surface of the test track under overload conditions. Afterward, the vehicle was driven laps again at 5 km / h, and then the speed was gradually increased to measure the speed at which the driver would experience an abnormality.

[0284] Next, the results of Comparative Examples 1-5 were set to 100, and the durability performance was expressed as an index according to the following formula for relative evaluation. The larger the value, the better the durability.

[0285] Durability = [(Results of the test tires) / (Results of Comparative Examples 1-5)] × 100

[0286] (3) Comprehensive evaluation

[0287] The evaluation results of (1) and (2) above are added together to obtain a comprehensive evaluation.

[0288] (4) Evaluation Results

[0289] The results of each evaluation are shown in Tables 1 and 2.

[0290] [Table 1]

[0291]

[0292] [Table 2]

[0293]

[0294] [Experiment 2]

[0295] In this experiment, a 195-size tire was prepared and evaluated.

[0296] 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 in Experiment 1, the parameters were calculated by performing the same steps. Then, performance evaluation tests were conducted and evaluated in the same manner. In this experiment, the result of Comparative Example 2-5 was set to 100 for evaluation. The results of each evaluation are shown in Tables 3 and 4.

[0297] [Table 3]

[0298]

[0299] [Table 4]

[0300]

[0301] [Experiment 3]

[0302] In this experiment, 225-size tires were prepared and evaluated.

[0303] 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 in Experiment 1, the parameters were calculated by performing the same steps. Then, performance evaluation tests were conducted and evaluated in the same manner. In this experiment, the result of Comparative Example 3-5 was set to 100 for evaluation. The results of each evaluation are shown in Tables 5 and 6.

[0304] [Table 5]

[0305]

[0306] [Table 6]

[0307]

[0308] [Summary of Experiments 1 to 3]

[0309] The results from Experiments 1 to 3 (Tables 1 to 6) show that for tires of any size (175, 195, 225), the results indicate that when the tire has a bead reinforcement layer and further satisfies the above (Equation 1) and (Equation 2), it can provide a pneumatic tire with reduced rolling resistance at high speeds and excellent durability.

[0310] Then, the results show that by meeting the requirements of this disclosure (2) and thereafter, tires with further reduced rolling resistance at high speeds and excellent durability can be provided.

[0311] On the other hand, the results show that when the tire does not have a bead reinforcement layer, or when either (Equation 1) or (Equation 2) is not satisfied, the reduction in rolling resistance at high speeds and the excellent durability performance cannot be fully achieved.

[0312] [Experiment 4]

[0313] Next, three tires (Examples 4-1 to 4-3) with no significant difference in the relationship between the hypothetical volume V and the cross-sectional width Wt were produced using the same formula and evaluated in the same manner. Here, in addition to evaluating rolling resistance and durability at high speeds as described above, ride comfort was also evaluated.

[0314] Specifically, test tires were installed on all wheels of a vehicle (a Japanese-made FF car with a 2000cc engine), inflated to an internal pressure of 250 kPa, and then driven on a dry road test track. After the vehicle traveled 10 km at 100 km / h, drivers conducted a sensory test of ride comfort on a 5-point scale. The evaluations from 20 drivers were summed, and the results were expressed as an index according to the following formula; where the total score in Examples 4-3 was set to 100 points, and a relative evaluation of ride comfort was performed. A higher value indicates better ride comfort.

[0315] Ride comfort = [(Total evaluation score of the test tires) / (Total evaluation score of Example 4-3)] × 100

[0316] Then, as in Experiments 1 through 3, the evaluation results were summed to obtain a comprehensive evaluation. Table 7 shows the results of each evaluation.

[0317] [Table 7]

[0318]

[0319] Table 7 shows that when there is no significant difference in the relationship between the hypothetical volume V and the cross-sectional width Wt, as the cross-sectional width Wt decreases, for example from less than 205 mm to less than 200 mm, and as the flatness increases, the rolling resistance and durability at high speeds are improved.

[0320] Although this disclosure has been described above with reference to embodiments, this disclosure is not limited to the embodiments described above. Various modifications can be made to the above embodiments within the same and equivalent scope as this disclosure.

[0321] This disclosure (1) is as follows:

[0322] A pneumatic tire has a bead portion, a carcass, and a tread, wherein a bead reinforcement layer is disposed on the axially outer side of the carcass, and the bead reinforcement layer reinforces the bead portion from the outer side of the carcass; and

[0323] Let the cross-sectional width of a tire mounted on a standardized rim with an internal pressure of 250 kPa be Wt (mm), the outer diameter be Dt (mm), and the volume of space occupied by the tire be the hypothetical volume V (mm²). 3 If the tire satisfies the following equations (1) and (2):

[0324] 1600≤(Dt 2 (×π / 4) / Wt≤2827.4 (Equation 1)

[0325] [(V+1.5×10 7 ) / Wt]≤2.88×10 5 (Equation 2).

[0326] This disclosure (2) is a pneumatic tire according to this disclosure (1), wherein the pneumatic tire satisfies the following (Equation 3):

[0327] [(V+2.0×10 7 ) / Wt]≤2.88×10 5 (Equation 3).

[0328] This disclosure (3) is a pneumatic tire according to this disclosure (2), wherein the pneumatic tire satisfies the following (Equation 4):

[0329] [(V+2.5×10 7 ) / Wt]≤2.88×10 5 (Equation 4)

[0330] This disclosure (4) is an inflatable tire according to any combination of this disclosure (1) to (3), wherein the outer diameter of the tire when mounted on a standardized rim and with an internal pressure of 250 kPa is set as Dt (mm) and the section height of the tire is Ht (mm), then (Dt-2×Ht) is 470 (mm) or more.

[0331] This disclosure (5) is a pneumatic tire according to any combination of this disclosure (1) to (4), wherein the aspect ratio of the pneumatic tire is 40% or more.

[0332] This disclosure (6) is a pneumatic tire according to this disclosure (5), wherein the aspect ratio of the pneumatic tire is 45% or more.

[0333] This disclosure (7) is a pneumatic tire according to this disclosure (6), wherein the aspect ratio of the pneumatic tire is 47.5% or more.

[0334] This disclosure (8) is a pneumatic tire according to this disclosure (7), wherein the aspect ratio of the pneumatic tire is 50% or more.

[0335] This disclosure (9) is a pneumatic tire according to any combination of this disclosure (1) to (8), wherein the ratio (tanδ / E*) of the loss tangent of the bead reinforcement layer to the complex elastic modulus (E*:MPa) measured at a temperature of 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1% is 0.005 or less.

[0336] This disclosure (10) is a pneumatic tire according to any combination of this disclosure (1) to (9), wherein, in a radial section view of the tire, the height of the bead reinforcement layer from below the bead core is less than 45% of the height from below the bead core to the outermost surface of the tread.

[0337] This disclosure (11) is a pneumatic tire according to any combination of this disclosure (1) to (10), wherein the ratio of the loss tangent (tanδ) to the complex elastic modulus (E*:MPa) (tanδ / E*), measured under conditions of a temperature of 70°C, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain rate of 1%, and the tire's cross-sectional width Wt (mm) and imaginary volume V (mm²) are also considered. 3 It satisfies the following (Equation 5):

[0338] (tanδ / E*)×(V / Wt)≤400 (Equation 5).

[0339] This disclosure (12) is a pneumatic tire according to this disclosure (11), wherein the tire satisfies the following (Equation 6):

[0340] (tanδ / E*)×(V / Wt)≤300 (Equation 6).

[0341] This disclosure (13) is a pneumatic tire according to any combination of this disclosure (1) to (12), wherein the tire has a sidewall formed using a rubber composition having a loss tangent (tanδ) of less than 0.08 as measured at a temperature of 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%.

[0342] This disclosure (14) is an inflatable tire according to this disclosure (13), wherein the complex modulus of elasticity (E*:MPa) of the rubber composition forming the sidewall is 4.0MPa or less, measured at a temperature of 70°C, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain rate of 1%.

[0343] This disclosure (15) is an inflatable tire according to any combination of this disclosure (1) to (14), wherein the tire has an overlap formed using a rubber composition having a loss tangent (tanδ) of less than 0.10 as measured at a temperature of 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%.

[0344] This disclosure (16) is an inflatable tire according to this disclosure (15), wherein the rubber composition forming the overlap has a complex elastic modulus (E*:MPa) of 8.0MPa or more, measured at a temperature of 70°C, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain rate of 1%.

[0345] This disclosure (17) is for a pneumatic tire according to any combination of this disclosure (1) to (16), wherein,

[0346] The tread portion has circumferential grooves that extend continuously in the tire circumferential direction, and

[0347] The groove width L at 80% of the maximum depth of the circumferential groove 80 The ratio of the groove width L0 of the circumferential grooves in the tread contact surface (L) 80 / L0) is 0.3 to 0.7.

[0348] This disclosure (18) is for a pneumatic tire according to any combination of this disclosure (1) to (17), wherein,

[0349] The tread portion has multiple circumferential grooves extending continuously in the tire circumferential direction, and

[0350] The total cross-sectional area of ​​multiple circumferential grooves is 10% to 30% of the cross-sectional area of ​​the tread.

[0351] This disclosure (19) is for a pneumatic tire according to any combination of this disclosure (1) to (18), wherein,

[0352] The tread portion has multiple lateral grooves extending axially along the tire, and

[0353] The total volume of the multiple lateral grooves is 2.0% to 5.0% of the tread volume.

[0354] This disclosure (20) is a pneumatic tire according to any combination of this disclosure (1) to (19), wherein Dt is less than 685 (mm), said Dt (mm) being the outer diameter of the tire when mounted on a standardized rim with an internal pressure of 250 kPa.

[0355] This disclosure (21) is a pneumatic tire according to any combination of this disclosure (1) to (20), wherein the cross-sectional width Wt (mm) is less than 205 mm.

[0356] This disclosure (22) is an inflatable tire according to this disclosure (21), wherein the cross-sectional width Wt (mm) is less than 200 mm.

[0357] This disclosure (23) is an inflatable tire according to any combination of this disclosure (1) to (22), wherein the inflatable tire is a passenger car inflatable tire.

[0358] Explanation of reference markers

[0359] 1. Bead reinforcement layer

[0360] 3rd tire sidewall

[0361] 4. Overlapping parts

[0362] 5 fetuses

[0363] 6 Inner Lining

[0364] 21 Bead Triangle

[0365] 22 tire bead core

Claims

1. A pneumatic tire having a bead portion, a carcass, and a tread, wherein, A bead reinforcing layer is provided on the tire axial outside of the carcass, and the bead reinforcing layer reinforces the bead portion from the outside of the carcass; The ratio tanδ / E* of the loss tangent tanδ to the complex elastic modulus E* (MPa) of the bead reinforcing layer measured at 70°C, at a frequency of 10 Hz, at an initial strain of 5%, and at a dynamic strain rate of 1% is 0.005 or less, The cross-sectional width of the tire mounted on a standardized rim and having an internal pressure of 250 kPa is set as Wt (mm), the outer diameter is Dt (mm), the volume of the space occupied by the tire is the imaginary volume V (mm 3 ), and the tire satisfies the following Equation 1 and Equation 4: 1600 ≤ (Dt 2 x π / 4) / Wt ≤ 2827.4 Equation 1 [(V + 2.5x10 7 ) / Wt] ≤ 2.75 x10 5 Equation 4 Also, a ratio tan δ / E* of a loss tangent tan δ measured at a temperature of 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%, and a complex elastic modulus E* (MPa), and a cross-sectional width Wt (mm) and an imaginary volume V (mm3) of the tire satisfy the following formula 5: 3 tan δ / E* = 0.0005WtV + 0.0005 (tanδ / E*) x (V / Wt) ≤ 400 Formula 5.

2. The pneumatic tire of claim 1, wherein, The outer diameter of the tire mounted on a standardized rim and having an internal pressure of 250 kPa is set to Dt (mm), the cross-sectional height of the tire is Ht (mm), and (Dt - 2 x Ht) is 470 (mm) or more.

3. The pneumatic tire of claim 1, wherein, The pneumatic tire has a flatness of 40% or more.

4. The pneumatic tire of claim 3, wherein, The pneumatic tire has a flatness of 45% or more.

5. The pneumatic tire of claim 4, wherein, The pneumatic tire has a flatness of 47.5% or more.

6. The pneumatic tire of claim 5, wherein, The pneumatic tire has a flatness of 50% or more.

7. The pneumatic tire of any one of claims 1 to 6, wherein, The ratio tanδ / E* of the loss tangent tanδ to the complex elastic modulus E* (MPa) of the bead reinforcing layer measured at 70°C, at a frequency of 10 Hz, at an initial strain of 5%, and at a dynamic strain rate of 1% is 0.0023 or less.

8. The pneumatic tire of any one of claims 1 to 6, wherein, In a tire radial cross-sectional view, the height of the bead reinforcing layer from below the bead core is 45% or less of the height from below the bead core to the outermost surface of the tread.

9. The pneumatic tire of claim 1, wherein, The tire satisfies the following Formula 6: (tanδ / E*) x (V / Wt) ≤ 300 Formula 6.

10. A pneumatic tire according to any one of claims 1 to 6, wherein, The tire has a side wall formed using a rubber composition having a loss tangent tanδ of 0.08 or less measured at 70°C, at a frequency of 10 Hz, at an initial strain of 5%, and at a dynamic strain rate of 1%.

11. The pneumatic tire of claim 10, wherein, The rubber composition forming the side wall has a complex elastic modulus E* (Mpa) of 4.0 MPa or less measured at 70°C, at a frequency of 10 Hz, at an initial strain of 5%, and at a dynamic strain rate of 1%.

12. A pneumatic tire according to any one of claims 1 to 6, wherein, The tire has a lap portion formed using a rubber composition having a loss tangent tanδ of 0.10 or less measured at 70°C, at a frequency of 10 Hz, at an initial strain of 5%, and at a dynamic strain rate of 1%.

13. The pneumatic tire of claim 12, wherein, The rubber composition forming the lap portion has a complex elastic modulus E* (Mpa) of 8.0 MPa or more measured at 70°C, at a frequency of 10 Hz, at an initial strain of 5%, and at a dynamic strain rate of 1%.

14. The pneumatic tire according to any one of claims 1 to 6, wherein the tread has a plurality of circumferential grooves continuously extending in the tire circumferential direction, and A groove width L at a depth of 80% of a maximum depth of the circumferential groove 80 A ratio L of the groove width L0 of the circumferential groove in the ground-contacting surface of the tread 80 / L0 is 0.3 to 0.

7.

15. The pneumatic tire according to any one of claims 1 to 6, wherein the tread has a plurality of circumferential grooves continuously extending in the tire circumferential direction, and the total cross-sectional area of the plurality of circumferential grooves is 10% to 30% of the cross-sectional area of the tread.

16. The pneumatic tire according to any one of claims 1 to 6, wherein the tread has a plurality of transverse grooves extending in the tire axial direction, and the total volume of the plurality of transverse grooves is 2.0% to 5.0% of the volume of the tread.

17. A pneumatic tire according to any one of claims 1 to 6, wherein, Dt is less than 685 (mm), said Dt (mm) being the outer diameter of the tire mounted on a standardized rim and at an internal pressure of 250 kPa.

18. A pneumatic tire according to any one of claims 1 to 6, wherein, The cross-sectional width Wt (mm) is less than 205 mm.

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

20. A pneumatic tire according to any one of claims 1 to 6, wherein, The pneumatic tire is a pneumatic tire for a passenger vehicle.

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