Pneumatic tire

Abstract

Provided is a pneumatic tire that balances ride comfort at low temperatures and steering stability at high speeds, the pneumatic tire having a tread portion that has: two or more circumferential grooves that extend continuously in the circumferential direction of the tire; a pair of shoulder land portions separated by the circumferential grooves and a center land portion located between the pair of shoulder land portions; and a transverse groove; and can optionally have or not have a sipe. When the tire cross-sectional width is Wt (mm) and the tire outer diameter is Dt (mm), Wt and Dt satisfy the following equation (1); the area of the entire land portion is Sr, and the total area of the center land portion is S ce r ce satisfy the following equation (2); the tread portion has at least one rubber layer composed of a rubber composition containing a rubber component, tan δ at 5°C (5°C tan δ), tan δ at 20°C (20°C tan δ), and tan δ at 50°C (50°C tan δ) of the rubber composition, measured under conditions of a frequency of 10 Hz and an elongation strain of 2.5%, satisfy the following equation (3) and the following equation (4). Equation (1) 1963.4 ≤ (π / 4) × (Dt^2 / Wt) ≤ 2827.4 Equation (2) 0.35 ≤ S ce r / Sr ≤ 0.80 Equation (3) 0.01 ≤ |20°C tan δ + 50°C tan δ| / 2 ≤ 0.17 Equation (4) 0.30 ≤ |5°C tan δ + 20°C tan δ| / 2 ≤ 0.60.

Description

Technical Field

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

[0002] In recent years, in addition to the significant improvement in automobile equipment and performance, the road network has also expanded and developed, resulting in more frequent high-speed driving. Especially at high speeds, there is a demand for tires with a basic tread that can always improve stable handling and ride comfort.

[0003] For example, Patent Document 1 discloses a pneumatic tire with a base tread incorporating collagen particles. However, it does not adequately meet the requirements for handling stability and ride comfort at high speeds.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2004-269684 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] The purpose of this invention is to provide a tire that balances ride comfort at low temperatures and handling stability at high speeds.

[0009] means of solving technical problems

[0010] The inventors conducted in-depth research and found that, among tires whose cross-sectional width and outer diameter meet the specified requirements, by setting specific conditions for the viscoelasticity of the tread rubber and the contact area of ​​the tread portion, a tire that balances ride comfort at low temperatures and handling stability at high speeds can be obtained, thus completing this invention.

[0011] That is, the present invention relates to:

[0012] [1]: A pneumatic tire having a tread portion having: two or more circumferential grooves extending continuously along the circumference of the tire; a pair of shoulder contact portions separated by the circumferential grooves and a central contact portion located between the pair of shoulder contact portions; and lateral grooves; and may or may not have sipes; when the tire cross-sectional width is set to Wt (mm) and the tire outer diameter is set to Dt (mm), Wt and Dt satisfy the following formula (1); when the area of ​​the entire contact portion is set to Sr and the total area of ​​the central contact portion is set to S ce At that time, Sr and S ceThe following formula (2) is satisfied; the above-mentioned tread has at least one rubber layer composed of a rubber composition containing rubber components, and the tanδ at 5°C (5°C tanδ), tanδ at 20°C (20°C tanδ) and tanδ at 50°C (50°C tanδ) measured at a frequency of 10 Hz and a tensile strain of 2.5% satisfy the following formula (3) and the following formula (4).

[0013] Formula (1)1963.4≤(π / 4)×(Dt^2 / Wt)≤2827.4

[0014] Equation (2) 0.35≤S ce / Sr≤0.80

[0015] Formula (3)0.01≤|20℃tanδ+50℃tanδ| / 2≤0.17

[0016] Formula (4)0.30≤|5℃tanδ+20℃tanδ| / 2≤0.60

[0017] [2]: The pneumatic tire as described in [1], wherein the value of the above formula (3) is less than 0.15.

[0018] [3]: Pneumatic tires as described in [1] or [2], wherein the value of the above formula (4) is 0.35 to 0.55.

[0019] [4]: A pneumatic tire as described in any one of [1] to [3], wherein the value of the above formula (3) is less than 0.14.

[0020] [5]: A pneumatic tire as described in any one of [1] to [4], wherein the value of the above formula (4) is 0.40 to 0.55.

[0021] [6]: The pneumatic tire as described in any one of [1] to [5], wherein the 5°C tanδ of the rubber composition is 0.65 or more.

[0022] [7]: The pneumatic tire as described in any one of [1] to [6], wherein the 5°C tanδ of the rubber composition is 0.70 or more.

[0023] [8]: The pneumatic tire as described in any one of [1] to [7], wherein the tanδ of the rubber composition at 20°C is 0.25 or less.

[0024] [9]: The pneumatic tire as described in any one of [1] to [8], wherein the tanδ of the rubber composition at 20°C is 0.20 or less.

[0025]

[10] : The pneumatic tire as described in any one of [1] to [9], wherein the tanδ of the rubber composition at 20°C is 0.15 or less.

[0026]

[11] : The pneumatic tire as described in any one of [1] to

[10] , wherein when the circumferential length of the tire is set to La, the sum of the lengths of the lateral side components of the lateral groove to Lb1 and the sum of the lengths of the lateral side components of the sipe to Lb2 is set to Lb, La and Lb satisfy the following formula (5).

[0027] Equation (5) 0.10≤La / Lb≤0.50

[0028]

[12] : The pneumatic tire as described in any one of [1] to

[11] , wherein the total length of the lateral side component of the lateral groove in the shoulder contact portion is Lb. sh The total length Lb of the lateral side component of the sipes in the tire shoulder contact area mentioned above. sh The sum of 2 Lb sh The total length Lb of the transverse side component of the transverse trench in the central grounding portion. ce The total length Lb of the transverse side component of the knife groove in the central grounding portion mentioned above. ce The sum of 2 Lb ce The ratio Lb sh / Lb ce For Lb sh / Lb ce <1.

[0029]

[13] : The pneumatic tire as described in any one of [1] to

[12] , wherein the width of at least one of the above-mentioned central ground contact portions is more than 1.4 times the groove depth of the circumferential groove adjacent to the tire in the lateral direction.

[0030]

[14] : The pneumatic tire as described in any of [1] to

[13] , wherein when the ground contact area of ​​the tread surface is set to St, and the sum of the total area of ​​the circumferential groove Sg1 and the total area of ​​the lateral groove and the sipe Sg2 is set to Sg, St and Sg satisfy the following formula (6).

[0031] Equation (6) 0.15≤Sg / St≤0.35

[0032]

[15] : The pneumatic tire as described in

[14] , wherein Sg1 / St is 0.09 to 0.16 and Sg2 / St is 0.08 to 0.14.

[0033]

[16] : The pneumatic tire as described in any one of [1] to

[15] , wherein the ratio of the value of the above formula (3) to the value of the above formula (2) is 0.15 to 0.30.

[0034]

[17] : The pneumatic tire as described in any one of [1] to

[16] , wherein the ratio of the value of the above formula (4) to the value of the above formula (2) is 0.80 to 1.30.

[0035]

[18] : The pneumatic tire as described in any one of

[11] to

[17] , wherein the ratio of the value of the above formula (3) to the value of the above formula (5) is 0.30 to 1.05.

[0036]

[19] : The pneumatic tire as described in any one of

[11] to

[18] , wherein the ratio of the value of the above formula (4) to the value of the above formula (5) is 2.1 to 3.8.

[0037]

[20] : A pneumatic tire as described in any one of

[14] to

[19] , wherein the ratio of the value of the above formula (4) to the value of the above formula (6) is 1.7 to 2.7.

[0038]

[21] : A pneumatic tire as described in any one of [1] to

[20] , wherein the tire is a passenger car tire.

[0039] Invention Effects

[0040] The pneumatic tire of the present invention, by setting specific conditions for the tire's cross-sectional width and outer diameter, the viscoelasticity of the tread rubber, and the contact area of ​​the tread portion, can balance ride comfort at low temperatures and handling stability at high speeds. Attached Figure Description

[0041] Figure 1 This is a partially unfolded view showing the tread pattern of the pneumatic tire of the present invention. Detailed Implementation

[0042] The following description, with reference to the accompanying drawings, illustrates an embodiment of the pneumatic tire of the present invention. It should be noted that the embodiment shown below is merely an example, and the pneumatic tire of the present invention is not limited to the following embodiment.

[0043] Figure 1 This is a unfolded view of the tread portion 1. The tread portion 1 forms a tread pattern that specifies the direction of installation on the vehicle. The tread pattern of the tread portion 1 is formed in an asymmetrical shape relative to the tire equator C.

[0044] The tread portion 1 has an outer tread end To and an inner tread end Ti. The outer tread end To is located on the outer side of the vehicle when mounted on it. Figure 1(The middle is the right side). The inner tread end Ti is located inside the vehicle when installed. Figure 1 (The middle is the left side).

[0045] To and Ti at each tread end represent the normal tire load and the normal load, respectively, and the lateral tire W when the tire touches the ground at a camber angle of 0 degrees. Figure 1 The left-right direction (hereinafter referred to as lateral W) is the outermost contact point. "Regular condition" refers to the state where the tire is assembled on a regular rim, inflated to the correct pressure, and unloaded. Unless otherwise stated in this manual, the dimensions of the tire (tire cross-section width Wt, tire outer diameter Dt, etc.) are values ​​measured under the aforementioned regular condition. In the regular condition, the lateral distance W between the outer tread end To and the inner tread end Ti is defined as the tread width TW.

[0046] "Standard rim" refers to the rim specified by the standard for each type of tire within a standard system that includes the standard on which the tire is based. If it is JATMA, it means "standard rim"; if it is TRA, it means "design rim"; and if it is ETRTO, it means "measuring rim".

[0047] "Standard tire pressure" refers to the tire pressure specified by each standard for each type of tire within a standard system that includes the tire's reference standards. If it is JATMA, it refers to "maximum tire pressure". If it is TRA, it refers to the maximum value recorded in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES". If it is ETRTO, it refers to "INFLATION PRESSURE".

[0048] "Regular load" refers to the load specified by each standard for each type of tire within the standard system, including the standard on which the tire is based. If it is JATMA, it refers to "maximum load capacity". If it is TRA, it refers to the maximum value recorded in the table "TIRE LOAD LIMITSAT VARIOUS COLD INFLATION PRESSURES". If it is ETRTO, it refers to "LOADCAPACITY".

[0049] The tread portion 1 has two or more circumferential grooves 11, 12, and 13 that extend continuously along the circumferential direction C. Figure 1 In this invention, three circumferential grooves 11, 12, and 13 are provided. However, the number of circumferential grooves is not particularly limited, and for example, it can be 2 to 5. In addition, in this invention, the circumferential grooves 11, 12, and 13 extend in a straight line along the circumferential direction C, but are not limited to this manner. For example, they can also extend in a wavy, sinusoidal, or zigzag shape along the circumferential direction C.

[0050] The width of each of the circumferential grooves 11, 12, and 13 can be arbitrarily determined according to convention. In order to provide sufficient drainage performance while maintaining the tread pattern rigidity 1, the width of each of the circumferential grooves 11, 12, and 13 is preferably, for example, about 2.5% to 5% of the tread width TW. The depth of each of the circumferential grooves 11, 12, and 13 is not particularly limited, but is preferably 5.0 to 12.0 mm, more preferably 6.0 to 11.0 mm, and even more preferably 7.0 to 10.0 mm.

[0051] In this invention, "shoulder grounding portion" refers to a pair of grounding portions formed between the outermost circumferential groove on the lateral side of the tire starting from the equator C and the ends To and Ti of each tread. Figure 1 The tire has two parts: an outer shoulder grounding portion 16 formed between the outermost circumferential groove 12 and the outer tread end To when it is installed in a vehicle, and an inner shoulder grounding portion 17 formed between the innermost circumferential groove 11 and the inner tread end Ti when it is installed in a vehicle.

[0052] Two or more shoulder transverse grooves 21 and 22 and two or more shoulder slits 23 and 24 extending in a direction transverse to the shoulder contact portions 16 and 17 are provided. Each pair of shoulder contact portions 16 and 17 has two or more shoulder transverse grooves 21 and 22 and two or more shoulder slits 23 and 24. It should be noted that in this specification, the shoulder transverse groove and shoulder slit provided on the outer shoulder contact portion 16 are referred to as outer shoulder transverse groove 21 and outer shoulder slit 23, respectively. Furthermore, the shoulder transverse groove and shoulder slit provided on the inner shoulder contact portion 17 are referred to as inner shoulder transverse groove 22 and inner shoulder slit 24, respectively.

[0053] In this invention, "central grounding part" refers to all the grounding parts sandwiched between the above-mentioned pair of tire shoulder grounding parts. Figure 1 The tire has an outer central grounding portion 18 formed between a circumferential groove 13 along the tire equator C and the outermost circumferential groove 12 when installed on a vehicle, and an inner central grounding portion 19 formed between a circumferential groove 13 along the tire equator C and the innermost circumferential groove 11 when installed on a vehicle. However, there is no particular limitation on the number of central grounding portions, for example, it can be 1 to 5.

[0054] The central grounding portions 18 and 19 are provided with two or more central transverse grooves 25 and 26 and two or more central knife-slots 27 and 28 extending in a direction transversely to the central grounding portions 18 and 19, respectively. It should be noted that, in this specification, the central transverse groove and central knife-slot provided on the outer central grounding portion 18 are referred to as the outer central transverse groove 25 and the outer central knife-slot 27, respectively. Furthermore, the central transverse groove and central knife-slot provided on the inner central grounding portion 19 are referred to as the inner central transverse groove 26 and the inner central knife-slot 28, respectively.

[0055] The width of each of the lateral grooves 21, 22, 25, and 26 is preferably, for example, about 2.5% to 5% of the tread width TW. The depth of each of the lateral grooves 21, 22, 25, and 26 is not particularly limited, but is preferably 5.0 to 12.0 mm, more preferably 6.0 to 11.0 mm, and even more preferably 7.0 to 10.0 mm. It should be noted that, in this specification, "groove" refers to a fine cut with a width of 2.0 mm or less, preferably 0.5 to 1.5 mm.

[0056] The shoulder contact portions 16 and 17 may also be provided with shoulder grooves 29 and 30 extending along the tire circumference. Thus, the shoulder contact portions 16 and 17 can be divided into: outer plates 16A and 17A disposed between the shoulder grooves 29 and 30 and the tread ends To and Ti, and inner plates 16B and 17B disposed on the tire equator C side of the outer plates 16A and 17A.

[0057] By providing the aforementioned shoulder grooves 29 and 30, the circumferential edge component of the tire can be increased, improving turning performance. Furthermore, because the circumferential rigidity of the outer sidewalls 16A and 17A and the inner sidewalls 16B and 17B is significantly ensured, driving performance on dry roads is improved. It should be noted that in this invention, the shoulder grooves 29 and 30 extend in a straight line along the circumferential direction C, but are not limited to this arrangement; for example, they can also extend in a wavy, sinusoidal, or zigzag shape along the circumferential direction C. The groove width W2 of the shoulder grooves 29 and 30 is preferably, for example, 1.0% to 2.0% of the tread width TW. The groove depth of the shoulder grooves 29 and 30 is preferably, for example, 0.40 to 0.60 times the depth of the deepest part of the circumferential grooves 11, 12, and 13.

[0058] In addition, in this invention, such as Figure 1As shown, the blade grooves 27 and 28 of the central grounding portions 18 and 19 extend to connect the two edges on the transverse W of the central grounding portions 18 and 19. The angle θ formed by the straight line connecting the two ends of the transverse W of the blade grooves 27 and 28 of the central grounding portions 18 and 19 and the circumferential groove 12 is preferably in the range of 60 to 80 degrees. In this case, a water film can be scraped out in the central grounding portions 18 and 19, improving braking performance on wet road surfaces.

[0059] The tire of the present invention is characterized in that, when the tire cross-sectional width is set to Wt (mm) and the tire outer diameter is Dt (mm), Wt and Dt satisfy the following formula (1). It should be noted that, in this specification, "tire cross-sectional width" refers to the maximum width between the outer surfaces of the tire sidewalls when the tire has patterns or text on the sidewall under normal conditions.

[0060] Formula (1)1963.4≤(π / 4)×(Dt^2 / Wt)≤2827.4

[0061] Furthermore, the tire of the present invention is characterized in that the area of ​​the entire ground contact portion is set as Sr, and the total area of ​​the central ground contact portion is set as S. ce At that time, Sr and S ce The following equation (2) must be satisfied;

[0062] Equation (2) 0.35≤S ce / Sr≤0.80

[0063] The value of equation (2) (S) ce The value of Sr is 0.35 or more, preferably 0.38 or more, more preferably 0.40 or more, even more preferably 0.42 or more, and particularly preferably 0.44 or more. Furthermore, the value of formula (2) (Sr) is... ce The ratio of Sr to the total area of ​​the central contact patch is 0.80 or less, preferably 0.70 or less, more preferably 0.65 or less, even more preferably 0.60 or less, and particularly preferably 0.55 or less. By making the ratio of the total area of ​​the central contact patch to the total area of ​​the tire contact patch within the above range, the volume of the central contact patch can be increased, the rigidity of the contact patch can be increased, and thus better handling stability can be obtained.

[0064] In addition, from the perspective of achieving the same effect, the width of the grounding part of at least one central grounding part is preferably 1.4 times or more the depth of the groove of the circumferential groove adjacent to the lateral outer side of the tire, more preferably 1.5 times or more, and even more preferably 1.6 times or more.

[0065] Regarding the tire of the present invention, when the ground contact area of ​​the tread is set to St, and the sum of the total area of ​​the circumferential grooves Sg1 and the total area of ​​the lateral grooves and the sipes Sg2 is set to Sg, St and Sg preferably satisfy the following formula (6). It should be noted that, in this specification, "ground contact area of ​​the tread" refers to the ground contact area of ​​the tread when all the grooves of the tread 1 are filled.

[0066] Equation (6) 0.15≤Sg / St≤0.35

[0067] The value of formula (6) (Sg / St) is preferably 0.15 or more, more preferably 0.18 or more, and even more preferably 0.21 or more. In addition, the value of formula (6) (Sg / St) is preferably 0.35 or less, more preferably 0.30 or less, and even more preferably 0.25 or less.

[0068] The Sg1 / St ratio is preferably 0.09 or more, more preferably 0.10 or more, and even more preferably 0.11 or more. Furthermore, the Sg1 / St ratio is preferably 0.16 or less, more preferably 0.14 or less, and even more preferably 0.13 or less.

[0069] The Sg2 / St ratio is preferably 0.08 or higher, more preferably 0.09 or higher, and even more preferably 0.10 or higher. Furthermore, the Sg2 / St ratio is preferably 0.14 or lower, more preferably 0.13 or lower, and even more preferably 0.12 or lower.

[0070] By ensuring that the ratio of the total groove area, the total area of ​​the circumferential grooves, and the total area of ​​the lateral grooves and sipes to the contact patch area is within the aforementioned range, the contact patch rigidity of the tread can be increased. Furthermore, based on the synergistic effect with the rubber softness of the tread rubber composition of the present invention, high handling stability can be achieved at high speeds, while improving ride comfort at low temperatures. If the ratio of the total groove area, the total area of ​​the circumferential grooves, and the total area of ​​the lateral grooves and sipes to the contact patch area is less than the aforementioned range, the contact patch ratio increases excessively, tending to decrease drainage and grip. Conversely, if the ratio of the total groove area, the total area of ​​the circumferential grooves, and the total area of ​​the lateral grooves and sipes to the contact patch area is greater than the aforementioned range, sufficient tread contact patch rigidity cannot be obtained, tending to decrease handling stability.

[0071] It should be noted that in this specification, the area Sr of the entire grounding part and the total area S of the central grounding part are... ceThe total area Sg1 of the circumferential grooves and the total area Sg2 of the lateral grooves and sipes are calculated from the contact patch shape when the tread is pressed against a flat surface under normal load. The contact patch shape is obtained by mounting the tire to a normal rim, maintaining normal internal pressure, applying ink to the tread portion 1, and pressing it perpendicularly onto thick paper or the like under normal load (camber angle 0°), thus transferring the ink applied to the tread portion 1. Furthermore, the area obtained based on the outer contour of the obtained contact patch shape is set as the contact patch area St of the tread portion when all grooves are filled.

[0072] Regarding the tire in this invention, when the length of the circumferential C of the tire 1 is set to La, and the sum of the lengths of the side components of the lateral W of the lateral grooves 21, 22, 25, 26 to Lb1 and the sum of the lengths of the side components of the lateral W of the sipes 23, 24, 27, 28 to Lb2 is set to Lb, it is preferable that La and Lb satisfy the following formula (5).

[0073] Equation (5) 0.10≤La / Lb≤0.50

[0074] The value of formula (5) (La / Lb) is preferably 0.10 or more, more preferably 0.12 or more, even more preferably 0.13 or more, and particularly preferably 0.14 or more. Furthermore, the value of formula (5) (La / Lb) is preferably 0.50 or less, more preferably 0.40 or less, even more preferably 0.30 or less, and particularly preferably 0.25 or less. By ensuring that the relationship between the lengths of the side components of the lateral grooves 21, 22, 25, 26 and the sipes 23, 24, 27, 28 and the circumferential length La of the tire 1 is within the above-mentioned range, it is possible to ensure that the deformation of the tread portion 1 is within a specified range and the area of ​​the contact portions 16, 17, 18, 19 of the tread portion 1 is at least specified. When the rubber composition described later is used in the tread, it is possible to improve handling stability at high speeds.

[0075] It should be noted that the "length of the side component of the transverse W" of transverse grooves 21, 22, 25, 26 and cutter grooves 23, 24, 27, 28 refers to the projected length of transverse grooves 21, 22, 25, 26 and cutter grooves 23, 24, 27, 28 in the transverse W (the transverse component and the transverse component in the circumferential component).

[0076] Furthermore, the ratio La / Lb1 of the length La of the tire's circumferential C and the total length Lb1 of the side components of the lateral W of the lateral grooves 21, 22, 25, 26 is preferably 0.18 to 0.70, more preferably 0.21 to 0.60, and even more preferably 0.24 to 0.50. By ensuring that the relationship between the total length Lb1 of the side components of the lateral W of the lateral grooves 21, 22, 25, 26 and the length La of the tire's circumferential C falls within the above range, the effect of the rubber composition described later can be further improved.

[0077] In addition, the total length Lb of the side components of the lateral W in the lateral grooves 21 and 22 in the tire shoulder contact portions 16 and 17 is... sh The total length Lb of the lateral W side components of the sipes 23 and 24 in the shoulder contact portions 16 and 17 is as follows: sh The sum of 2 Lb sh The total length Lb of the side components of the transverse W of the transverse trenches 25 and 26 in the central grounding parts 18 and 19. ce The total length Lb of the transverse W side components of the knife grooves 27 and 28 in the central grounding parts 18 and 19 is 1. ce The sum of 2 Lb ce The ratio Lb sh / Lb ce Preferably Lb sh / Lb ce <1. In this case, the edge components in the tire shoulder contact portions 16 and 17 become smaller, and the rigidity of the tire shoulder contact portions 16 and 17 increases. As a result, wear on the tire shoulder contact portions 16 and 17 can be suppressed, and handling stability at high speeds can be improved.

[0078] In this invention, "5℃tanδ", "20℃tanδ" and "50℃tanδ" refer to the loss tangent tanδ at 5℃, 20℃ and 50℃, respectively, measured under conditions of a frequency of 10Hz and a tensile strain of 2.5%. The rubber composition of this invention is characterized in that 5℃tanδ, 20℃tanδ and 50℃tanδ satisfy the following equations (3) and (4).

[0079] Formula (3)0.01≤|20℃tanδ+50℃tanδ| / 2≤0.17

[0080] Formula (4)0.30≤|5℃tanδ+20℃tanδ| / 2≤0.60

[0081] Considering the effects of the present invention, the value of formula (3) (|20℃tanδ+50℃tanδ| / 2) is 0.01 or more, preferably 0.03 or more, more preferably 0.05 or more, even more preferably 0.07 or more, and particularly preferably 0.09 or more. Furthermore, the value of formula (3) (|20℃tanδ+50℃tanδ| / 2) is 0.17 or less, preferably 0.16 or less, more preferably 0.15 or less, even more preferably 0.14 or less, and particularly preferably 0.13 or less.

[0082] Considering the effects of the present invention, the value of formula (4) (|5℃tanδ+20℃tanδ| / 2) is 0.30 or more, preferably 0.32 or more, more preferably 0.34 or more, even more preferably 0.36 or more, and particularly preferably 0.38 or more. Furthermore, the value of formula (4) (|5℃tanδ+20℃tanδ| / 2) is 0.60 or less, preferably 0.58 or less, more preferably 0.56 or less, even more preferably 0.54 or less, and particularly preferably 0.52 or less.

[0083] Considering the effects of the present invention, tanδ at 5°C is preferably 0.65 or higher, more preferably 0.70 or higher, even more preferably 0.80 or higher, and particularly preferably 0.85 or higher. Furthermore, the upper limit of tanδ at 5°C is not particularly limited, but is preferably 1.50 or lower, more preferably 1.40 or lower, and even more preferably 1.30 or lower.

[0084] Considering the effects of the present invention, tanδ at 20°C is preferably 0.25 or less, more preferably 0.20 or less, even more preferably 0.15 or less, and particularly preferably 0.10 or less. Furthermore, the lower limit of tanδ at 20°C is not particularly limited, but is preferably 0.01 or more, more preferably 0.03 or more, and even more preferably 0.05 or more.

[0085] Considering the effects of the present invention, the ratio of the value of formula (3) to the value of formula (2) is preferably 0.05 or more, more preferably 0.10 or more, and even more preferably 0.15 or more. In addition, the ratio of the value of formula (3) to the value of formula (2) is preferably 0.40 or less, more preferably 0.35 or less, and even more preferably 0.30 or less.

[0086] Considering the effects of the present invention, the ratio of the value of formula (4) to the value of formula (2) is preferably 0.70 or more, more preferably 0.75 or more, and even more preferably 0.80 or more. In addition, the ratio of the value of formula (4) to the value of formula (2) is preferably 1.50 or less, more preferably 1.30 or less, and even more preferably 1.10 or less.

[0087] Considering the effects of the present invention, the ratio of the value of formula (3) to the value of formula (5) is preferably 0.15 or more, more preferably 0.30 or more, and even more preferably 0.45 or more. In addition, the ratio of the value of formula (3) to the value of formula (5) is preferably 1.05 or less, more preferably 0.95 or less, and even more preferably 0.85 or less.

[0088] Considering the effects of the present invention, the ratio of the value of formula (4) to the value of formula (5) is preferably 1.8 or more, more preferably 2.1 or more, and even more preferably 2.4 or more. In addition, the ratio of the value of formula (4) to the value of formula (5) is preferably 3.8 or less, more preferably 3.6 or less, and even more preferably 3.4 or less.

[0089] Considering the effects of the present invention, the ratio of the value of formula (4) to the value of formula (6) is preferably 1.5 or more, more preferably 1.6 or more, and even more preferably 1.7 or more. In addition, the ratio of the value of formula (4) to the value of formula (6) is preferably 3.0 or less, more preferably 2.7 or less, and even more preferably 2.4 or less.

[0090] The tread layer of the present invention has at least one rubber layer. This rubber layer may be formed from a single rubber layer, or it may have one or more rubber layers further inside the tire radial direction of the rubber layer (tread rubber layer) forming the tread surface on the outer surface. When the rubber layer consists of two or more layers, at least one of the two or more rubber layers may be composed of the rubber composition specified above; preferably, the tread rubber layer is composed of the rubber composition specified above.

[0091] The rubber composition specified above is preferably used in the following rubber layer, which is present in part or all of the deepest part of the bottom of the deepest groove among the circumferential grooves 11, 12, 13 and the lateral grooves 21, 22, 25, 26 to the outermost part in the tire radial direction; more preferably, it is used in the following rubber layer, which is present in the entirety from the deepest part of the bottom of the deepest groove to the outermost part in the tire radial direction. When the rubber composition specified above is used in the tread rubber layer, the tread rubber layer is preferably present in the entirety from the deepest part of the bottom of the deepest groove among the circumferential grooves 11, 12, 13 and the lateral grooves 21, 22, 25, 26 to the outermost part in the tire radial direction.

[0092] [Rubber Composition]

[0093] Regarding the tire of the present invention, through the cooperation of the above-described tire structure, especially the shape of the tread, and the above-described physical properties of the rubber composition, it is possible to more effectively improve ride comfort at low temperatures and handling stability at high speeds.

[0094] <Rubber Composition>

[0095] The rubber composition of the present invention preferably contains at least one selected from the group consisting of isoprene rubber, styrene-butadiene rubber (SBR) and butadiene rubber (BR) as a rubber component, more preferably containing SBR, even more preferably containing SBR and BR, or may be a rubber component consisting only of SBR and BR.

[0096] (SBR)

[0097] There are no particular limitations on the type of SBR used, and examples include solution polymerization SBR (S-SBR), emulsion polymerization SBR (E-SBR), and modified SBRs of these (modified S-SBR, modified E-SBR), etc. Examples of modified SBRs include SBRs with modified ends and / or main chains, and modified SBRs coupled with tin, silicon compounds, etc. (condensation polymers, substances with branched structures, etc.). Among these, S-SBR and modified SBR are preferred. Furthermore, hydrides of these SBRs (hydrogenated SBRs), etc., can be used. These SBRs can be used individually or in combination of two or more.

[0098] Examples of S-SBRs that can be used in this invention include those manufactured and sold by JSR Corporation, Sumitomo Chemical Co., Ltd., Ube Industries, Ltd., Asahi Kasei Corporation, and ZS Elastomers Co., Ltd.

[0099] From the perspective of wet grip performance and abrasion resistance, the styrene content of SBR is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. Furthermore, from the perspective of temperature dependence of grip performance and burst resistance, it is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. It should be noted that the styrene content of SBR in this specification is based on... 1 Calculated by H-NMR measurement.

[0100] From the perspective of ensuring reactivity with silica, wet grip performance, rubber strength, and abrasion resistance, the vinyl content of SBR is preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more. Furthermore, from the perspective of preventing increased temperature dependence, elongation at break, and abrasion resistance, the vinyl content of SBR is preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 60 mol% or less. It should be noted that the vinyl content (1,2-bonded butadiene unit weight) of SBR in this specification is determined by infrared absorption spectroscopy.

[0101] From the perspective of wet grip performance, the weight-average molecular weight (Mw) of SBR is preferably 200,000 or more, more preferably 250,000 or more, and even more preferably 300,000 or more. Furthermore, from the perspective of crosslinking uniformity, the weight-average molecular weight is preferably 2,000,000 or less, more preferably 1,800,000 or less, and even more preferably 1,500,000 or less. It should be noted that the weight-average molecular weight of SBR in this specification can be calculated from the value determined using gel permeation chromatography (GPC) (e.g., GPC-8000 series manufactured by Tosoh Corporation; detector: differential refractometer; column: TSKGEL SUPERMALTIPORE HZ-M manufactured by Tosoh Corporation) and converted using standard polystyrene.

[0102] In the case of SBR, from the perspective of wet grip performance, its content in 100% by mass of the rubber component is preferably 40% by mass or more, more preferably 50% by mass or more, further preferably 60% by mass or more, and particularly preferably 70% by mass or more. Furthermore, there is no particular limit to the upper limit of the SBR content in the rubber component, and it can be 100% by mass.

[0103] (BR)

[0104] There are no particular limitations on BR (butadiene rubber). Commonly used BRs in the tire industry include, for example, BRs with less than 50% cis-1,4 bond content (cis content) (low cis BR), BRs with more than 90% cis-1,4 bond content (high cis BR), rare earth-based butadiene rubber synthesized using rare earth element catalysts (rare earth BR), BRs containing syndiotactic polybutadiene crystals (BRs containing SPB), and modified BRs (high cis modified BR, low cis modified BR), etc. These BRs can be used alone or in combination with two or more types.

[0105] Examples of modified butadiene rubber (BR) include: BR obtained by polymerizing 1,3-butadiene using a lithium initiator followed by the addition of a tin compound, and further modified by bonding the ends of the BR molecule with tin-carbon bonds (tin-modified BR); and butadiene rubber with condensation polyalkoxysilane compounds at the active ends (silicone-modified BR). Examples of such modified BRs include tin-modified BR and silicon-modified BR manufactured and sold by companies such as ZS Elastomers Co., Ltd.

[0106] From the perspective of abrasion resistance, the weight-average molecular weight (Mw) of BR is preferably 300,000 or more, more preferably 350,000 or more, and even more preferably 400,000 or more. Furthermore, from the perspective of crosslinking uniformity, it is preferably 2 million or less, more preferably 1 million or less. It should be noted that the weight-average molecular weight of BR can be calculated from the value determined using gel permeation chromatography (GPC) (e.g., GPC-8000 series manufactured by Tosoh Corporation; detector: differential refractometer; column: TSK GEL SUPER MALTIPORE HZ-M manufactured by Tosoh Corporation) and converted using standard polystyrene.

[0107] When BR is present, from the perspective of wet grip performance, its content in 100% by mass of the rubber component is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 20% by mass or less. Furthermore, there is no particular limitation on the lower limit of the BR content, and it can be set to, for example, 1% by mass or more, 3% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more.

[0108] (Isoprene-based rubber)

[0109] As isoprene-based rubbers, commonly used rubbers in the tire industry, such as isoprene rubber (IR) and natural rubber, can be used. Besides unmodified natural rubber (NR), natural rubber also includes modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, and grafted natural rubber. These isoprene-based rubbers can be used alone or in combination with two or more.

[0110] There are no special restrictions on NR, and commonly used materials in the tire industry can be used, such as SIR20, RSS#3, TSR20, etc.

[0111] When isoprene-based rubber is included, from the perspective of wet grip performance, its content in 100% by mass of the rubber component is preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, and particularly preferably 20% by mass or less. Furthermore, there is no particular limitation on the lower limit of the content of isoprene-based rubber, and it can be set to, for example, 1% by mass or more, 3% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more.

[0112] <Other Rubber Components>

[0113] As the rubber component of this invention, it may also contain rubber components other than the aforementioned isoprene-based rubbers, SBR, and BR. Other rubber components may be crosslinkable rubber components commonly used in the tire industry, such as styrene-isoprene-butadiene copolymer (SIBR), styrene-isobutylene-styrene block copolymer (SIBS), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), hydrogenated nitrile butadiene rubber (HNBR), butyl rubber (IIR), ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylate rubber (ACM), chlorohydrin rubber, etc. These other rubber components may be used individually or in combination of two or more.

[0114] <packing>

[0115] As a filler, the rubber composition of the present invention preferably contains silica, and more preferably contains carbon black and silica.

[0116] (Carbon black)

[0117] As carbon black, commonly used carbon blacks in the tire industry can be appropriately utilized, such as GPF, FEF, HAF, ISAF, and SAF. These carbon blacks can be used alone or in combination of two or more.

[0118] From the perspective of enhancing performance, the nitrogen adsorption specific surface area (N2SA) of carbon black is preferably 10 m² / s. 2 / g or more, preferably 20m 2 / g or more. Furthermore, considering low fuel consumption and processability, 200m is preferred. 2 / g or less, more preferably 150m 2 / g or less, more preferably 100m 2 / g or less, more preferably 80m 2 / g or less, especially preferably 50m 2 / g or less. It should be noted that the N2SA of carbon black is a value determined according to JIS K 6217-2 "Basic properties of carbon black for rubber - Part 2: Calculation method of specific surface area - Nitrogen adsorption method - Single point method".

[0119] When carbon black is present, from the perspective of abrasion resistance and wet grip performance, the carbon black content is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 parts by mass of rubber composition. Furthermore, from the perspective of low oil consumption performance, it is preferably 50 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less.

[0120] (Silicon dioxide)

[0121] There are no particular restrictions on the type of silica used; materials commonly used in the tire industry, such as anhydrous silica prepared by a dry process or hydrated silica prepared by a wet process, can be used. However, hydrated silica prepared by a wet process is preferred due to its higher silanol group content. One type of silica can be used alone, or two or more can be used in combination.

[0122] From the perspectives of low fuel consumption and wear resistance, the nitrogen adsorption specific surface area (N2SA) of silica is preferably 140 m². 2 / g or more, preferably 170m 2 / g or more, further preferably 200m 2 / g or more. Furthermore, considering low fuel consumption and processability, 350m is preferred. 2 / g or less, more preferably 300m 2 / g or less, more preferably 250m 2 / g or less. It should be noted that the N2SA of silica in this specification is the value determined by the BET method according to ASTM D3037-93.

[0123] When silica is present, from the perspective of wet grip performance, the silica content is preferably 20 parts by mass or more, more preferably 40 parts by mass or more, further preferably 50 parts by mass or more, and particularly preferably 60 parts by mass or more, relative to 100 parts by mass of rubber composition. Furthermore, from the perspective of abrasion resistance, it is preferably 130 parts by mass or less, more preferably 120 parts by mass or less, and further preferably 110 parts by mass or less.

[0124] From the perspective of abrasion resistance, the total content of silica and carbon black is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more, relative to 100 parts by mass of rubber composition. Furthermore, from the perspective of low oil consumption and elongation at break, it is preferably 160 parts by mass or less, more preferably 140 parts by mass or less, and even more preferably 120 parts by mass or less.

[0125] The proportion of silicon dioxide relative to the total content of silicon dioxide and carbon black is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 85% by mass or more.

[0126] (Other packing materials)

[0127] As a filler other than silica and carbon black, it can be combined with aluminum hydroxide, calcium carbonate, alumina, clay, talc and other substances commonly used in the tire industry to date.

[0128] (Silane coupling agent)

[0129] Silica is preferably used in combination with a silane coupling agent. There are no particular limitations on the silane coupling agent; any silane coupling agent traditionally used in the tire industry in combination with silica can be used. Examples include, for instance, mercapto-based silane coupling agents; sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl)disulfide and bis(3-triethoxysilylpropyl)tetrasulfide; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; and 3-aminopropyltriethoxysilane. Amino-based silane coupling agents such as 3-aminopropyltrimethoxysilane and 3-(2-aminoethyl)aminopropyltriethoxysilane; epoxy-based silane coupling agents such as γ-epoxypropoxypropyltriethoxysilane and γ-epoxypropoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chlorinated silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferred, with mercapto-based silane coupling agents being more preferred. These silane coupling agents can be used alone or in combination of two or more.

[0130] The mercaptosilane coupling agent is preferably a compound represented by formula (7) below, and / or a compound containing bonding unit A represented by formula (8) below and bonding unit B represented by formula (9) below.

[0131] [Chemistry 1]

[0132]

[0133] (where R is in the formula) 101 R 102 and R 103 Each independently represents an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or a -O-(R) group. 111 -O) z -R 112 (z R) 111 Each independently represents a divalent hydrocarbon group with 1 to 30 carbon atoms; R 112 The radical (z) represents an alkyl group with 1 to 30 carbon atoms, an alkenyl group with 2 to 30 carbon atoms, an aryl group with 6 to 30 carbon atoms, or an aralkyl group with 7 to 30 carbon atoms; z represents an integer from 1 to 30. The radical (R) represents the group. 104 This refers to alkylene groups having 1 to 6 carbon atoms.

[0134] [Chemistry 2]

[0135]

[0136] [Chemistry 3]

[0137]

[0138] (In the formula, x represents an integer greater than or equal to 0; y represents an integer greater than or equal to 1; R) 201 Represents a hydrogen atom, an alkyl group with 1 to 30 carbon atoms that can be substituted with a halogen atom, a hydroxyl group, or a carboxyl group, or an alkyne group with 2 to 30 carbon atoms; R 202 This indicates an alkylene group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, or an ynylene group having 2 to 30 carbon atoms; here, R 201 and R 202 It can form a ring structure.

[0139] Examples of compounds represented by formula (7) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and compounds represented by formula (10) below (Si363 manufactured by Evonik Degussa). Compounds represented by formula (10) below are preferred. One of these compounds may be used alone, or two or more may be used together.

[0140] [Chemistry 4]

[0141]

[0142] Examples of compounds comprising bonding unit A as represented by formula (8) and bonding unit B as represented by formula (9) include compounds manufactured and sold by companies such as Momentive. These can be used individually or in combination of two or more.

[0143] When a silane coupling agent is included, the total content of the silane coupling agent relative to 100 parts by weight of the rubber component, from the perspective of improving the dispersibility of silica, is preferably 0.5 parts by weight or more, more preferably 1.0 parts by weight or more, further preferably 2.0 parts by weight or more, and particularly preferably 4.0 parts by weight or more. Furthermore, from the perspective of preventing a decrease in abrasion resistance, it is preferably 20 parts by weight or less, more preferably 12 parts by weight or less, further preferably 10 parts by weight or less, and particularly preferably 9.0 parts by weight or less.

[0144] Relative to 100 parts by weight of silica, from the perspective of improving the dispersibility of silica, the content of silane coupling agent (the total amount when two or more silane coupling agents are used) is preferably 1.0 parts by weight or more, more preferably 3.0 parts by weight or more, and particularly preferably 5.0 parts by weight or more. Furthermore, from the perspective of cost and processability, it is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and even more preferably 12 parts by weight or less.

[0145] In addition to carbon black and silica, other fillers can be used as fillers. There are no particular limitations on such fillers; any of the fillers commonly used in this field, such as aluminum hydroxide, alumina, calcium carbonate, magnesium sulfate, talc, and clay, can be used. These fillers can be used individually or in combination of two or more.

[0146] <Other compounding agents>

[0147] In addition to the above-mentioned components, the rubber composition of the present invention may also contain appropriate compounding agents commonly used in the tire industry, such as softeners, waxes, processing aids, stearic acid, zinc oxide, anti-aging agents, vulcanizing agents, vulcanization accelerators, etc.

[0148] (Softener)

[0149] The rubber composition of the present invention preferably contains a plasticizer. Examples of plasticizers include resin components, oils, liquid rubbers, and ester-based plasticizers.

[0150] There are no particular limitations on resin components; examples commonly used in the tire industry include petroleum resins, terpene resins, rosin resins, and phenolic resins. These resin components can be used individually or in combination of two or more.

[0151] In this specification, "C5 series petroleum resin" refers to resin obtained by polymerizing C5 fractions. Examples of C5 fractions include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferably used as a C5 series petroleum resin.

[0152] In this specification, "aromatic petroleum resin" refers to resin obtained by polymerizing C9 fractions, or resins obtained by hydrogenation or modification of C9 fractions. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of aromatic petroleum resins preferably include coumarone-indene resin, coumarone resin, indene resin, and aromatic vinyl resins. As aromatic vinyl resins, α-methylstyrene, homopolymers of styrene, or copolymers of α-methylstyrene and styrene are preferred due to their economic efficiency, ease of processing, and excellent exothermic properties; copolymers of α-methylstyrene and styrene are more preferred. Commercially available resins such as those from Kraton and Eastman Chemical can be used as aromatic vinyl resins.

[0153] In this specification, "C5C9 series petroleum resin" refers to a resin obtained by copolymerizing the aforementioned C5 fraction and the aforementioned C9 fraction, or it may be a resin obtained by hydrogenating or modifying them. Examples of C5 and C9 fractions include the aforementioned petroleum fractions. Commercially available resins, such as those from Tosoh Corporation and Luhua Corporation, can be used as C5C9 series petroleum resins.

[0154] Examples of terpene-based resins include polyterpene resins composed of at least one terpene compound selected from α-pinene, β-pinene, limonene, and dipentene; aromatic modified terpene resins using the aforementioned terpene compounds and aromatic compounds as raw materials; terpene-phenol resins using terpene compounds and phenolic compounds as raw materials; and resins that have undergone hydrogenation treatment of these terpene-based resins (hydrogenated terpene resins). Examples of aromatic compounds used as raw materials for aromatic modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenolic compounds used as raw materials for terpene-phenol resins include phenol, bisphenol A, cresol, and xylenol.

[0155] As a rosin-based resin, there are no particular limitations. Examples include natural rosin resin and rosin-modified resins that have been modified by hydrogenation, disproportionation, dimerization, esterification, etc.

[0156] As for phenolic resins, there are no particular limitations; examples include phenolic resins, alkylphenolic resins, alkylphenol acetylene resins, and oil-modified phenolic resins.

[0157] From the perspective of wet grip performance, the softening point of the resin component is preferably 60°C or higher, more preferably 65°C or higher. Furthermore, from the perspective of processability and improving the dispersibility of the rubber component and filler, it is preferably 150°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower. It should be noted that, in this specification, the softening point can be defined as the temperature decrease that the ball drops when measured using a ring-and-ball softening point tester, as specified in JIS K 6220-1:2001.

[0158] When resin components are present, from the perspective of wet grip performance, the resin component content is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 parts by mass of rubber component. Furthermore, from the perspective of suppressing exothermic reactions, it is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less.

[0159] Examples of oils include processing oils, vegetable oils, and animal fats. Among these processing oils, paraffinic processing oils, cycloalkane-based processing oils, and aromatic processing oils are examples. Furthermore, as an environmental countermeasure, processing oils with low polycyclic aromatic compounds (PCA) content can be used. Examples of processing oils with low PCA content include mild extraction solvates (MES), treated distillate aromatic extracts (TDAE), and heavy cycloalkane oils.

[0160] When oil is present, from a processability perspective, the oil content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, relative to 100 parts by mass of the rubber component. Furthermore, from a wear resistance perspective, it is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 90 parts by mass or less. It should be noted that the oil content in this specification also includes the amount of oil contained in the oil-extended rubber.

[0161] Liquid rubber is not specifically limited to any polymer that is liquid at room temperature (25°C). Examples include liquid butadiene rubber (liquid BR), liquid styrene-butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene-isoprene rubber (liquid SIR), and liquid farnesene rubber. These liquid rubbers can be used alone or in combination with two or more.

[0162] When liquid rubber is present, the content of liquid rubber is preferably 1 part by mass or more, more preferably 2 parts by mass or more, further preferably 3 parts by mass or more, and particularly preferably 5 parts by mass or more, relative to 100 parts by mass of rubber component. Furthermore, the content of liquid rubber is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 20 parts by mass or less.

[0163] Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di(2-ethylhexyl) azelaate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), di(undecyl) phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), and tri(xyl) phosphate (TXP). These ester-based plasticizers can be used alone or in combination of two or more.

[0164] When an ester-based plasticizer is included, the content of the ester-based plasticizer relative to 100 parts by weight of the rubber component is preferably 1 part by weight or more, more preferably 2 parts by weight or more, even more preferably 3 parts by weight or more, and particularly preferably 5 parts by weight or more. Furthermore, the content of the ester-based plasticizer is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, and even more preferably 20 parts by weight or less.

[0165] Relative to 100 parts by weight of rubber composition, from the perspective of wet grip performance, the content of the softener (when using two or more softeners, the total amount) is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, and even more preferably 15 parts by weight or more. Furthermore, from the perspective of processability, it is preferably 120 parts by weight or less, more preferably 100 parts by weight or less, even more preferably 90 parts by weight or less, and particularly preferably 80 parts by weight or less.

[0166] When wax is present, from the perspective of rubber weather resistance, the wax content is preferably 0.5 parts by weight or more, and more preferably 1 part by weight or more, relative to 100 parts by weight of rubber component. Furthermore, from the perspective of preventing tire whitening caused by blooming, the wax content is preferably 10 parts by weight or less, and more preferably 5 parts by weight or less.

[0167] Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. These processing aids can be used individually or in combination of two or more. Commercially available products from companies such as Schill+Seilacher and Performance Additives can be used as processing aids.

[0168] When processing aids are included, the content of processing aids is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component, from the perspective of improving processability. Furthermore, from the perspective of abrasion resistance and breaking strength, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less.

[0169] There are no particular limitations on anti-aging agents; examples include compounds from amine, quinoline, quinone, phenol, and imidazole groups, as well as carbamate metal salts. Preferred anti-aging agents include N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylene diamine, N-isopropyl-N'-phenyl-p-phenylene diamine, N,N'-diphenyl-p-phenylene diamine, N,N'-di-2-naphthyl-p-phenylene diamine, and N-cyclohexyl-N'-phenyl-p-phenylene diamine, as well as quinoline-based anti-aging agents such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline. These anti-aging agents can be used alone or in combination of two or more.

[0170] When an anti-aging agent is included, from the perspective of the rubber's resistance to ozone cracking, the content of the anti-aging agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component. Furthermore, from the perspective of abrasion resistance and wet grip performance, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0171] When stearic acid is present, from a processability perspective, the stearic acid content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component. Furthermore, from a vulcanization rate perspective, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0172] When zinc oxide is present, from a processability perspective, the zinc oxide content is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component. Furthermore, from a wear resistance perspective, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0173] Sulfur is preferred as a vulcanizing agent. Powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersed sulfur can be used as sulfur.

[0174] When sulfur is used as a vulcanizing agent, the sulfur content is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, relative to 100 parts by mass of rubber component, to ensure a sufficient vulcanization reaction. Furthermore, from the perspective of preventing deterioration, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. It should be noted that when using oil-containing sulfur as a vulcanizing agent, the content of the vulcanizing agent is set as the total content of pure sulfur components contained in the oil-containing sulfur.

[0175] Examples of vulcanizing agents other than sulfur include alkylphenol-sulfur chloride condensate, sodium 1,6-hexamethylene-dithiosulfate dihydrate, and 1,6-bis(N,N'-dibenzylthiocarbamoyl dithio)hexane. These non-sulfur vulcanizing agents can be commercially available products from companies such as Taoka Chemical Industry Co., Ltd., LANXESS Co., Ltd., and Flexsys.

[0176] Examples of vulcanization accelerators include sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamate-based, aldehyde-amine-based or aldehyde-amine-based, imidazoline-based, or xanthate-based vulcanization accelerators. These vulcanization accelerators can be used alone or in combination of two or more. Preferably, one or more vulcanization accelerators selected from the group consisting of sulfenamide-based, guanidine-based, and thiazole-based vulcanization accelerators are chosen.

[0177] Examples of sulfenamide-based vulcanization accelerators include N-tert-butyl-2-benzothiazole sulfenamide (TBBS), N-cyclohexyl-2-benzothiazole sulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazole sulfenamide (DCBS). Among these, N-tert-butyl-2-benzothiazole sulfenamide (TBBS) is preferred.

[0178] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-toluidine, 1-o-toluidine biguanide, di-o-toluidine salts of biscatechol borate, 1,3-di-o-isopropylphenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-isopropylphenyl-2-propionylguanidine. Among these, 1,3-diphenylguanidine (DPG) is preferred.

[0179] Examples of thiazole-based sulfidation accelerators include 2-mercaptobenzothiazole, cyclohexylamine salts of 2-mercaptobenzothiazole, and dibenzothiazole disulfide. Among these, 2-mercaptobenzothiazole is preferred.

[0180] When a vulcanization accelerator is included, the content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 2 parts by mass or more, relative to 100 parts by mass of the rubber component. Furthermore, the content of the vulcanization accelerator is preferably 8 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 6 parts by mass or less, relative to 100 parts by mass of the rubber component. By keeping the content of the vulcanization accelerator within the above range, there is a tendency to ensure breaking strength and elongation.

[0181] The rubber composition of the present invention can be manufactured using known methods. For example, it can be manufactured by mixing the above-mentioned components using rubber mixing equipment such as open rollers, closed mixers (Banbury mixers, kneaders, etc.).

[0182] The mixing process includes, for example, a basic mixing process in which compounding agents and additives other than vulcanizing agents and vulcanization accelerators are mixed, and a final mixing (F-mixing) process in which vulcanizing agents and vulcanization accelerators are added to the mixture obtained in the basic mixing process and mixed. Furthermore, the above-mentioned basic mixing process can be divided into two or more processes as desired.

[0183] There are no particular limitations on the mixing conditions. For example, in the basic mixing process, mixing at a discharge temperature of 150–170°C for 3–10 minutes, and in the final mixing process, mixing at 70–110°C for 1–5 minutes. There are no particular limitations on the vulcanization conditions. For example, vulcanizing at 150–200°C for 10–30 minutes.

[0184] Regarding tires having a tread composed of the above-described rubber composition, they can be manufactured using the above-described rubber composition by conventional methods. That is, an uncured rubber composition in which the above-described components are incorporated as needed is extruded according to the shape of the tread, bonded together with other tire components on a tire forming machine, and formed by conventional methods to form an uncured tire. The uncured tire is then heated and pressurized in a vulcanizing machine, thereby manufacturing a tire.

[0185] The aforementioned rubber composition can be used in the treads of various tires, such as passenger car tires; truck and bus tires; two-wheeled vehicle tires; high-performance tires; studless tires, and other winter tires. These tires can also be: run-flat tires with a sidewall reinforcement layer; tires with sound-absorbing components, including a sponge or similar sound-absorbing component inside the tire cavity; tires with sealing components, including a sealant inside the tire or in the tire cavity to seal in case of a blowout; tires with electronic components, including sensors, wireless tags, or other electronic components inside the tire or in the tire cavity; etc.

[0186] Example

[0187] The present invention will be specifically described with reference to the embodiments, but the present invention is not limited to these embodiments.

[0188] The following is a summary of the various pharmaceutical agents used in the examples and comparative examples.

[0189] SBR1: S-SBR manufactured in Example 1 described later (styrene content: 30% by mass, vinyl content: 52% by mol%, Mw: 250,000, non-oil-extended).

[0190] SBR2: HP755 (S-SBR; styrene content: 40% by weight, vinyl content: 38 mol%, oil-extended product containing 37.5 parts by weight of oil per 100 parts by weight of rubber component) manufactured by JSR Corporation.

[0191] BR1: UBEPOL BR (registered trademark) 150B manufactured by Ube Industries, Ltd. (cis content: 97%, Mw: 440,000)

[0192] BR2: BR500 manufactured by JSR Corporation (cis content: 32%)

[0193] Carbon black: Diablack N220 (N2SA: 115m) manufactured by Mitsubishi Chemical Corporation 2 / g)

[0194] Silica: ULTRASIL (registered trademark) VN3 (N2SA: 175m) manufactured by Evonik Degussa. 2 / g)

[0195] Silane coupling agent 1: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa.

[0196] Silane coupling agent 2: NXT-Z45 (thiol-based silane coupling agent) manufactured by Momentive.

[0197] Ester-based plasticizer: TOP (tris(2-ethylhexyl) phosphate) manufactured by Daihachi Chemical Co., Ltd.

[0198] Resin composition: Sylvatraxx4401 (a copolymer of α-methylstyrene and styrene, softening point: 85℃) manufactured by Kraton.

[0199] Anti-aging agent: Antigen 3C (N-isopropyl-N'-phenyl-p-phenylene diamine) manufactured by Sumitomo Chemical Co., Ltd.

[0200] Stearic acid: Beaded stearic acid "Camellia" manufactured by Nippon Oil Co., Ltd.

[0201] Zinc oxide: Zinc White No. 1 manufactured by Mitsui Metals Mining Co., Ltd.

[0202] Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd.

[0203] Vulcanization accelerator 1: Soxinol CZ (N-cyclohexyl-2-benzothiazole sulfenamide) manufactured by Sumitomo Chemical Co., Ltd.

[0204] Vulcanization accelerator 2: Soxinol DG (N,N'-diphenylguanidine) manufactured by Sumitomo Chemical Co., Ltd.

[0205] Manufacturing Example 1: Synthesis of SBR1

[0206] Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were added to a nitrogen-purged autoclave reactor. After adjusting the reactor contents to 20°C, n-butyllithium was added to initiate polymerization. Polymerization was carried out under adiabatic conditions, reaching a maximum temperature of 85°C. 1,3-Butadiene was added when the polymerization conversion reached 99%, and after another 5 minutes of polymerization, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane was added as a modifier and the reaction proceeded. After the polymerization reaction was complete, 2,6-di-tert-butyl-p-cresol was added. Next, the solvent was removed by stripping, and the mixture was dried using a hot roller heated to 110°C to obtain SBR1.

[0207] According to the formulation shown in Table 1, using a 1.7L closed-type Banbury mixer, sulfur and all agents except the vulcanization accelerator were mixed at a discharge temperature of 160°C for 4 minutes to obtain a compound. Next, sulfur and the vulcanization accelerator were added to the obtained compound, and the mixture was mixed using open rollers for 4 minutes to obtain an unvulcanized rubber composition. Further, the obtained unvulcanized rubber composition was plate-cured at 170°C for 12 minutes to obtain a test vulcanized rubber sheet.

[0208] In addition, the obtained uncured rubber composition is used to shape the rubber sheets into tread shapes and bond them together with other components to produce a green tire. Then, in the vulcanization process, the tires are pressed at 170°C for 20 minutes to produce a test tire of size 195 / 65R15.

[0209] <Determination of tanδ>

[0210] Strip-shaped test pieces, 4 mm wide, 20 mm long, and 2 mm thick, were punched from the sheet-like vulcanized rubber composition for testing. Using a dynamic viscoelasticity measuring device (EPLEXOR series, registered trademark) manufactured by GABO, the tanδ values ​​at 5°C (5°C tanδ), 20°C (20°C tanδ), and 50°C (50°C tanδ) were measured at a frequency of 10 Hz and a tensile strain of 2.5%.

[0211] Handling stability at high speeds

[0212] All test tires were installed on all wheels of a domestically produced FF car with a displacement of 660cc, and the vehicle was driven on a test route with a dry asphalt surface at an temperature of 20℃~30℃. The handling characteristics were evaluated based on the test drivers' sensations during straight-line driving, lane changing, and acceleration / deceleration at 120km / h. Evaluations were given on an integer scale of 1 to 5 points, with higher scores indicating better handling characteristics. The total score of 10 test drivers was calculated. The total score of the benchmark comparison examples (Comparison Example 1 in Tables 3 and 4, and Comparison Example 5 in Tables 5 and 6) was converted to a benchmark value (100), and the evaluation results of each test tire were expressed as an index proportional to the total score.

[0213] <Ride comfort in low temperatures>

[0214] All test tires were installed on all wheels of a domestically produced FF car with a displacement of 660cc. The car was driven on a test route with a dry asphalt surface at temperatures ranging from -1℃ to -6℃. Drivers evaluated the ride comfort using sensory feedback. Evaluations were given on an integer scale of 1 to 5 points, with higher scores indicating better ride comfort. The total score for the 10 test drivers was calculated. The total score of the benchmark comparison examples (Comparison Example 1 in Tables 3 and 4, and Comparison Example 5 in Tables 5 and 6) was converted to a baseline value (100), and the evaluation results of each test tire were proportionally indexed to the total score.

[0215] [Table 1]

[0216]

[0217] [Table 2]

[0218]

[0219]

[0220] [Table 4]

[0221]

[0222] [Table 6]

[0223] The results in Tables 1 to 6 show that the pneumatic tire of the present invention, which sets specific conditions for the tire's cross-sectional width and outer diameter, the viscoelasticity of the tread rubber, and the contact area of ​​the tread portion, achieves a balanced improvement in ride comfort at low temperatures and handling stability at high speeds.

[0224] Symbol Explanation

[0225] 1. Fetal face

[0226] 11, 12, 13 Zhouxiang Ditch

[0227] 16. Outer shoulder contact patch

[0228] 17. Inner tire shoulder contact point

[0229] 18. Outer central grounding part

[0230] 19. Inner central grounding part

[0231] 21. Lateral shoulder groove

[0232] 22. Inner shoulder transverse groove

[0233] 23 Outer shoulder sipe

[0234] 24 Inner shoulder sipes

[0235] 25. Outer central transverse groove

[0236] 26. Inner central transverse groove

[0237] 27 Outer central groove

[0238] 28 Inner central groove

[0239] 29. Outer shoulder groove

[0240] 30 Inner shoulder groove

[0241] To the outer tread end

[0242] Ti inner tread end

[0243] W tire lateral

Claims

1. A pneumatic tire provided with a tread portion, wherein the tread portion has: two or more circumferential grooves continuously extending in the tire circumferential direction; a pair of shoulder land portions separated by the circumferential grooves and a center land portion located between the pair of shoulder land portions; and a transverse groove; the tread portion can optionally have or not have a sipe; when the tire cross-sectional width is set as Wt (mm) and the tire outer diameter is set as Dt (mm), Wt and Dt satisfy the following equation (1); the tread portion has at least one rubber layer composed of a rubber composition containing a rubber component, The area of the entire ground portion is set as Sr, and the total area of the central ground portions is set as S ce Sr and S ce satisfy the following equation (2); the rubber composition satisfies the following equation (3) and the following equation (4) with respect to tan δ at 5°C (5°C tan δ), tan δ at 20°C (20°C tan δ), and tan δ at 50°C (50°C tan δ) measured under the conditions of a frequency of 10 Hz and a tensile strain of 2.5%: equation (1) 1963.4 ≤ (π / 4) x (Dt2 / Wt) ≤ 2827.4 equation (3) 0.01 ≤ |20°C tan δ + 50°C tan δ| / 2 ≤ 0.17 0.35 < S ce / Sr < 0.80 equation (4) 0.30 ≤ |5°C tan δ + 20°C tan δ| / 2 ≤ 0.60, the 5°C tan δ of the rubber composition is 0.65 or greater, the 20°C tan δ of the rubber composition is 0.15 or less. the value of the equation (3) is less than 0.

15.

2. The pneumatic tire of claim 1, wherein, the value of the equation (4) is 0.35 to 0.

55.

3. The pneumatic tire of claim 1 or 2, wherein, the value of the equation (3) is less than 0.

14.

4. The pneumatic tire of claim 1 or 2, wherein, the value of the equation (4) is 0.40 to 0.

55.

5. The pneumatic tire of claim 1 or 2, wherein, the 5°C tan δ of the rubber composition is 0.70 or greater.

6. The pneumatic tire of claim 1 or 2, wherein, when the length of the tire circumferential direction is set as La and the sum of the length of the lateral component of the transverse direction of the transverse groove (Lb1) and the length of the lateral component of the transverse direction of the sipe (Lb2) is set as Lb, La and Lb satisfy the following equation (5), 7. The pneumatic tire of claim 1 or 2, wherein, equation (5) 0.10 ≤ La / Lb ≤ 0.

50. the land portion width of at least one of the center land portions is 1.4 times or greater the groove depth of the circumferential grooves adjacent in the tire transverse direction.

8. The pneumatic tire of claim 1 or 2, wherein, the sum Lb of the length of the lateral edge component of the lateral groove in the shoulder land sh 1 and the length of the lateral edge component of the sipe in the shoulder land sh 2 sh , the sum Lb of the length of the lateral edge component of the lateral groove in the center land ce 1 and the length of the lateral edge component of the sipe in the center land ce 2 ce sh ce sh ce <1.​​​​ 9. The pneumatic tire of claim 1 or 2, wherein, when the land area of the tread portion is set as St and the sum of the total area of the circumferential grooves (Sg1) and the total area of the transverse grooves and the sipes (Sg2) is set as Sg, St and Sg satisfy the following equation (6), 10. The pneumatic tire of claim 1 or 2, wherein, equation (6) 0.15 ≤ Sg / St ≤ 0.

35. Sg1 / St is 0.09 to 0.16 and Sg2 / St is 0.08 to 0.

14.

11. The pneumatic tire of claim 10, wherein, the ratio of the value of the equation (3) to the value of the equation (2) is 0.15 to 0.

30.

12. The pneumatic tire of claim 1 or 2, wherein, the ratio of the value of the equation (4) to the value of the equation (2) is 0.80 to 1.

30.

13. The pneumatic tire of claim 1 or 2, wherein, the ratio of the value of the equation (3) to the value of the equation (5) is 0.30 to 1.

05.

14. The pneumatic tire of claim 7, wherein, the ratio of the value of the equation (4) to the value of the equation (5) is 2.1 to 3.

8.

15. The pneumatic tire of claim 7, wherein, the ratio of the value of the equation (4) to the value of the equation (6) is 1.7 to 2.

7.

16. The pneumatic tire of claim 10, wherein, the tire is a passenger vehicle tire.

17. The pneumatic tire of claim 1 or 2, wherein, ​

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