Pneumatic tire

Abstract

To provide a pneumatic tire that can reduce road noise by attenuating vibration during travelling without impairing rolling resistance.SOLUTION: A pneumatic tire includes a tread part 1, a pair of side wall parts 2, and a pair of bead parts 3. A sealant layer 20 is formed in a tire inner surface 10 in the tread part 1. The sealant layer 20 has tanδ of which peak temperature is within a range of -120°C to -20°C. The peak value of the tanδ of the sealant layer 20 is 1.5 or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pneumatic tire having a sealant layer on the inner surface of the tire in the tread portion, and more particularly, to a pneumatic tire capable of reducing road noise by attenuating vibrations during running without deteriorating rolling resistance.

Background Art

[0002] In a pneumatic tire, it has been proposed to provide a sealant layer on the inner side in the tire radial direction of the inner liner layer in the tread portion. In such a pneumatic tire, when a foreign object such as a nail pierces the tread portion, the sealant flows into the through-hole, thereby suppressing a decrease in air pressure and enabling running to be maintained.

[0003] Conventionally, as the sealant constituting the sealant layer, a rubber composition mainly composed of butyl rubber is common (see, for example, Patent Documents 1 to 3). Examples of the butyl rubber include halogenated butyl rubbers such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR) in addition to butyl rubber (IIR). Such a sealant is applied to the inner surface of the tire in a state of being heated to a high temperature and softened (see, for example, Patent Document 4).

[0004] By the way, in recent years, the weight reduction of pneumatic tires has progressed, and it has become difficult to attenuate the vibrations of the tires due to the reduction of the amount of rubber. As a result, there is a problem that road noise deteriorates. On the other hand, when the amount of rubber is increased (for example, an increase in tread thickness), although the effect of attenuating the vibrations of the tire can be obtained, the rolling resistance increases accordingly. Thus, there is an antinomy relationship between the rolling resistance and the vibration characteristics.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a pneumatic tire that can reduce road noise by attenuating vibrations during running without deteriorating rolling resistance.

Means for Solving the Problems

[0007] The pneumatic tire of the present invention for achieving the above object is a pneumatic tire including a tread portion that extends in the tire circumferential direction and forms an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the inner side in the tire radial direction of these sidewall portions. A sealant layer is formed on the inner surface of the tire in the tread portion, the peak temperature of tanδ of the sealant layer is in the range of -120°C to -20°C, and the peak value of tanδ of the sealant layer is 1.5 or more.

Effects of the Invention

[0008] In the present invention, the peak temperature of tanδ of the sealant layer disposed in the tread portion is in the range of -120°C to -20°C, and the peak value of tanδ of the sealant layer is 1.5 or more, whereby vibrations during running can be attenuated and road noise can be reduced. More specifically, when the frequency of vibrations related to road noise among the vibrations generated in the tire during running (500 Hz to 3000 Hz) is converted to temperature based on the temperature-frequency conversion rule, it falls within the range of approximately -120°C to -20°C. When the peak value of tanδ of the sealant layer is high and the viscosity is high in this temperature region, vibrations related to road noise during running can be effectively attenuated. The temperature-frequency conversion rule is a rule for converting frequency to temperature by utilizing the fact that the viscoelastic behavior of a material changes by a constant multiple depending on temperature. And since such a vibration attenuation effect is obtained based on the physical properties of the sealant layer, it is not necessary to increase the amount of rubber in the pneumatic tire, and therefore, an increase in rolling resistance can be avoided.

[0009] In the present invention, it is preferable that the peak temperature of tanδ of the sealant layer is in the range of -90°C to -60°C. Thereby, vibrations in a frequency region with more vibrations can be attenuated, so that the effect of reducing road noise increases.

[0010] In the present invention, it is preferable that tanδ of the sealant layer at 100°C is in the range of 0.2 to 0.8. Thereby, the flow characteristics of the sealant layer during running can be optimized, and puncture sealing performance and flow resistance can be maintained well.

[0011] In the present invention, it is preferable that the loss shear elastic modulus G" of the sealant layer at 100°C is 5 kPa or less. Thereby, heat generation of the sealant layer during running is suppressed, so that the influence on the durability of the pneumatic tire can be suppressed.

[0012] In the present invention, a plurality of belt layers including belt cords inclined with respect to the tire circumferential direction are embedded in the tread portion, and the belt cords are arranged so as to cross each other between the layers. The plurality of belt layers include a first belt layer located on the innermost side in the tire radial direction and a second belt layer located on the outermost side in the tire radial direction. When a point 0.1Wb away from the end of the second belt layer toward the inner side in the tire width direction with respect to the width Wb of the second belt layer is defined as P1, and a point where a straight line extending in the tire radial direction passing through the point P1 intersects the tire inner surface is defined as P2, it is preferable that the end of the sealant layer is arranged on the outer side in the tire width direction than the point P2. By arranging the end of the sealant layer on the outer side in the tire width direction than the point P2, good puncture sealing performance can be ensured.

[0013] In the present invention, it is preferable that the thickness of the sealant layer is in the range of 2.0 mm to 5.0 mm. Thereby, while ensuring puncture sealing performance, it is possible to prevent deterioration of durability due to an increase in tire weight.

[0014] In the present invention, it is preferable that the sealant is composed of a silicone-based composition. A sealant composed of a silicone-based composition can exhibit excellent puncture sealing performance. In addition, a sealant composed of a silicone-based composition has the advantages of excellent weather resistance and low temperature dependence of physical properties. In particular, it is preferable that the silicone-based composition is a two-component curable silicone. Since the two-component curable silicone has a low viscosity immediately after mixing the two components, it can be applied even at low temperatures.

[0015] In the present invention, the loss tangent tanδ and the loss shear elastic modulus G" are measured in accordance with JIS-K6394 using a viscoelastic spectrometer in a tensile deformation mode under the conditions of each specified temperature, a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of ±2%.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0017] Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIGS. 1 and 2 show a pneumatic tire according to an embodiment of the present invention.

[0018] As shown in FIG. 1, the pneumatic tire of the present embodiment includes a tread portion 1 that extends in the tire circumferential direction and forms an annular shape, a pair of sidewall portions 2, 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3, 3 disposed on the inner side in the tire radial direction of these sidewall portions 2.

[0019] A carcass layer 4 is mounted between the pair of bead portions 3, 3. This carcass layer 4 includes a plurality of carcass cords extending in the tire radial direction, and is folded from the inner side to the outer side around a bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross-section is disposed on the outer periphery of the bead core 5.

[0020] On one side, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of belt cords inclined with respect to the tire circumferential direction, and are arranged such that the belt cords cross each other between the layers. The plurality of belt layers 7 include a first belt layer 7A located at the innermost side in the tire radial direction and a second belt layer 7B located outside the first belt layer 7A, and the width of the first belt layer 7A is wider than the width of the second belt layer 7B. In the belt layer 7, the inclination angle of the belt cord with respect to the tire circumferential direction is set in the range of, for example, 10° to 40°. As the belt cord of the belt layer 7, a steel cord is preferably used.

[0021] On the outer peripheral side of the belt layer 7, for the purpose of improving high-speed durability, at least one belt cover layer 8 is arranged in which reinforcing cords are arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction. It is desirable that this belt cover layer 8 has a jointless structure in which a strip material formed by rubber-coating at least one reinforcing cord aligned is continuously wound at substantially 0° with respect to the tire circumferential direction. As the reinforcing cord of the belt cover layer 8, organic fiber cords such as nylon and polyethylene terephthalate (PET) are preferably used.

[0022] Note that the above-described tire internal structure shows a typical example in a pneumatic tire, but is not limited thereto. In the tread portion 1, various grooves including a plurality of main grooves 11 extending in the tire circumferential direction are formed.

[0023] In the above pneumatic tire, a sealant layer 20 is formed on the inner surface 10 of the tread portion 1 so as to be continuous in the tire circumferential direction. It is preferable that the center position of the sealant layer 20 in the tire width direction coincides with the tire equator, but the center position may be shifted toward either one side in the tire width direction from the tire equator. The distance in the tire width direction between the center position of the sealant layer 20 in the tire width direction and the tire equator is preferably 10 mm or less, more preferably 5 mm or less. Thereby, the sealant layer 20 does not adversely affect the tire balance. The sealant of the sealant layer 20 may be composed of a rubber composition mainly composed of butyl rubber, but is preferably composed of a silicone-based composition. The silicone-based composition includes a synthetic polymer compound having a main skeleton formed by a siloxane bond.

[0024] Figure 3 shows the relationship between the temperature of the sealant layer and tanδ in the present invention. As shown in Figure 3, the peak temperature Tp of tanδ of the sealant layer 20 is in the range of -120°C to -20°C, and the peak value Vp of tanδ of the sealant layer 20 is 1.5 or more. The peak temperature Tp and the peak value Vp of tanδ of the sealant layer 20 can be adjusted, for example, based on the crosslinking degree of the sealant or the blending amount of the liquid polymer added to the sealant. Examples of the liquid polymer include liquid polybutene, liquid isobutene, liquid polyisoprene, liquid polybutadiene, liquid poly-α-olefin, liquid ethylene-propylene copolymer, liquid ethylene-butylene copolymer, and the like.

[0025] In the pneumatic tire configured as described above, since the peak temperature Tp of tanδ of the sealant layer 20 disposed in the tread portion 1 is in the range of -120°C to -20°C and the peak value Vp of tanδ of the sealant layer 20 is 1.5 or more, it is possible to attenuate vibrations during running and reduce road noise. And since this vibration damping effect is obtained based on the physical properties of the sealant layer 20, it is not necessary to increase the amount of rubber in the pneumatic tire, and therefore, an increase in rolling resistance can be avoided.

[0026] Here, if the peak temperature Tp of tanδ of the sealant layer 20 is out of the above range, the effect of reducing the load noise becomes insufficient. In particular, the peak temperature Tp of tanδ of the sealant layer 20 is preferably in the range of -90°C to -60°C. In this case, vibrations in a frequency region with more vibrations can be attenuated, so the effect of reducing the load noise increases. Also, if the peak value Vp of tanδ of the sealant layer 20 is less than 1.5, the effect of reducing the load noise becomes insufficient. The upper limit value of the peak value Vp of tanδ of the sealant layer 20 is not particularly limited, but for example, it may be 3.0 or less.

[0027] In the above pneumatic tire, it is preferable that the tanδ of the sealant layer 20 at 100°C is in the range of 0.2 to 0.8. Thereby, the flow characteristics of the sealant layer 20 during running can be optimized, and the puncture sealing property and the flow resistance can be maintained well. Here, if the tanδ of the sealant layer 20 at 100°C is less than 0.2, the puncture sealing property deteriorates, and conversely, if it is greater than 0.8, the flow resistance deteriorates. In particular, it is desirable that the tanδ of the sealant layer 20 at 100°C is in the range of 0.3 to 0.6.

[0028] In the above pneumatic tire, it is preferable that the loss shear elastic modulus G" of the sealant layer 20 at 100°C is 5 kPa or less. Thereby, the heat generation of the sealant layer 20 during running is suppressed, so the influence on the durability of the pneumatic tire can be suppressed. Here, if the loss shear elastic modulus G" of the sealant layer 20 at 100°C is greater than 5 kPa, the sealant layer 20 generates heat during running, and the durability of the pneumatic tire deteriorates. The upper limit value of the loss shear elastic modulus G" of the sealant layer 20 at 100°C is not particularly limited, but for example, it may be 3 kPa or less.

[0029] The pneumatic tire described above can be manufactured by the following method. First, a pneumatic tire having a tread portion 1, a pair of sidewall portions 2, and a pair of bead portions 3 as described above is manufactured. Next, a sealant made of, for example, a silicone-based composition is applied to the inner surface 10 of the tire in the tread portion 1 to form a sealant layer 20.

[0030] FIG. 4 shows a specific manufacturing method of the pneumatic tire of FIG. 1, and FIG. 5 shows a sealant layer formed on the inner surface of the tread portion. In FIG. 4, the sealant extruding device 31 mixes the sealant supplied from the pumps 32 and 33 and continuously discharges the mixed sealant from the nozzle 34 as a strip material 21. The sealant extruding device 31 is configured such that the position of the nozzle 34 can be displaced. Therefore, by moving the nozzle 34 in the tire axial direction while rotating the tire from a state where the nozzle 34 is close to the inner surface 10 of the tire, the strip material 21 of the sealant can be spirally arranged on the inner surface 10 of the tire while being inclined with respect to the tire circumferential direction Tc (see FIG. 5). The circumferential portions of the strip material 21 of the sealant arranged in a spiral shape are in close contact with each other. The strip material 21 of the sealant arranged in this spiral shape is integrated to form the sealant layer 20.

[0031] In the above-mentioned pneumatic tire, it is preferable that the sealant is composed of a silicone-based composition. A sealant layer 20 having a structure in which a strip material 21 of the sealant is spirally arranged along the tire circumferential direction on the inner surface 10 of the tread portion 1 is formed. Since the sealant is composed of a silicone-based composition, the circumferential portions of the sealant strip material 21 are easily adaptable to each other in the curing reaction process of the silicone-based composition, and the integrality between the circumferential portions of the sealant strip material 21 becomes good. Therefore, the sealing performance of the sealant layer 20 can be improved. Further, since the integrality between the circumferential portions of the sealant strip material 21 is good, it becomes difficult for the sealant layer 20 to flow toward the center side in the tire width direction due to the centrifugal force generated during tire rotation, and this also contributes to the improvement of the sealing performance. Furthermore, when a silicone-based composition is used as the sealant of the sealant layer 20, there are also advantages of excellent weather resistance and low temperature dependence of physical properties.

[0032] Since the silicone-based composition has good fluidity even at low temperatures, it is preferable that the temperature of the sealant applied to the inner surface 10 of the tire is lower than 70°C. Thereby, the influence of heat on the tire can be reduced, and the deterioration of tire performance can be avoided. When this temperature is 70°C or higher, the influence of heat on the tire becomes large, which becomes a factor for deteriorating tire performance. In particular, it is desirable that the temperature of the sealant applied to the inner surface 10 of the tire is 40°C or lower. Also, from the viewpoint of the fluidity of the silicone-based composition, it is preferable that the lower limit value of the temperature of the sealant applied to the inner surface 10 of the tire is 20°C.

[0033] As the silicone-based composition constituting the sealant of the sealant layer 20, one-component curable silicone or two-component curable silicone can be used, but it is particularly preferable to use two-component curable silicone. Examples of the one-component curable silicone include moisture curable silicone. The two-component curable silicone is composed of a first liquid and a second liquid. By mixing these first and second liquids, the curing reaction starts, and stability as the sealant layer 20 is ensured after curing. In the above-described apparatus, the first liquid and the second liquid of the two-component curable silicone are supplied from pumps 32 and 33, respectively. Since the two-component curable silicone has a low viscosity immediately after the two liquids are mixed, it can be applied even at a low temperature.

[0034] The two-component curable silicone is composed of, for example, a condensation curable silyl-terminated polymer, a silane crosslinking agent, a condensation catalyst, a filler, and the like. Examples of the condensation curable silyl-terminated polymer include polydialkylsiloxane, alkylphenylsiloxane, an organic polymer having a silyl group (for example, silyl polyether, silyl acrylate), and polyisobutylene having a silyl group. Examples of the silane crosslinking agent include alkoxy-functional silane, oximosilane, acetoxysilane, enoxysilane, and the like. Examples of the filler include iron oxide, titanium dioxide, carbon black, talc, and the like. Examples of the condensation catalyst include titanate, zirconate, and the like. These condensation curable silyl-terminated polymer, silane crosslinking agent, condensation catalyst, and filler are stored in a state divided into the first liquid and the second liquid in a combination in which the curing reaction does not proceed, and are mixed at the time of use.

[0035] In the pneumatic tire described above, a plurality of belt layers 7 are embedded in the tread portion 1, the belt layers 7 including belt cords inclined with respect to the tire circumferential direction and arranged such that the belt cords cross each other between the layers. When the plurality of belt layers 7 include a first belt layer 7A positioned innermost in the tire radial direction and a second belt layer 7B positioned outermost in the tire radial direction, as shown in FIGS. 1 and 2, a point P1 is defined as a point 0.1Wb away from the end of the second belt layer 7B toward the inner side in the tire width direction with respect to the width Wb of the second belt layer 7B. When a straight line extending in the tire radial direction passing through the point P1 intersects the tire inner surface 10 at a point P2, it is preferable that the end of the sealant layer 20 is disposed on the outer side in the tire width direction than the point P2. By disposing the end of the sealant layer 20 on the outer side in the tire width direction than the point P2, puncture sealing performance can be ensured favorably.

[0036] In the pneumatic tire described above, it is preferable that the end of the sealant layer 20 is disposed on the outer side in the tire width direction than the end of the belt layer 7 (7A, 7B). By making the width Ws of the sealant layer 20 sufficiently large, puncture of the pneumatic tire can be effectively prevented. Here, if the end of the sealant layer 20 is disposed on the inner side in the tire width direction than the point P2, the puncture sealing performance deteriorates.

[0037] In the pneumatic tire described above, when a belt cover layer 8 including an organic fiber cord oriented in the tire circumferential direction is embedded on the outer peripheral side of the belt layer 7 in the tread portion 1, it is preferable that the end of the sealant layer 20 is disposed on the outer side in the tire width direction than the end of the belt cover layer 8. By making the width Ws of the sealant layer 20 sufficiently large, puncture of the pneumatic tire can be effectively prevented.

[0038] In the above pneumatic tire, as shown in FIG. 2, it is preferable that the thickness S of the sealant layer 20 is in the range of 2.0 mm to 5.0 mm. Thereby, while ensuring puncture sealing performance, it is possible to prevent deterioration of durability due to an increase in tire weight. Here, if the thickness S of the sealant layer 20 is less than 2.0 mm, the puncture sealing performance will decrease. Conversely, if it is greater than 5.0 mm, the durability may deteriorate due to an increase in tire weight. The thickness S of the sealant layer 20 is the overall average thickness. Such an average thickness of the sealant layer 20 can be calculated, for example, by photographing the tire meridian cross-section at 8 locations on the tire circumference using a CT scan, and in each of the photographed images, measuring the thickness of the sealant layer 20 at 5 points: the tire equator position, the outer edge positions (both sides) 10 mm inward in the tire width direction from the edge of the sealant layer 20, and the intermediate positions (both sides) between the tire equator position and the outer edge positions, and then calculating from the measured values at a total of 40 points.

[0039] In the above pneumatic tire, as shown in FIG. 2, in all locations of the first belt layer 7A located at the innermost side in the tire radial direction, it is preferable that the distance (shortest distance) L from the first belt layer 7A to the sealant layer 20 is 10 mm or less. Thereby, when a foreign object such as a nail penetrates the tread portion 1, the sealant easily flows to the first belt layer 7A, so that good puncture sealing performance can be ensured. If there is a portion where the distance L from the first belt layer 7A to the sealant layer 20 is greater than 10 mm, the puncture sealing performance in that portion may become insufficient.

[0040] In the above pneumatic tire, it is preferable that the ratio of the thickness S of the sealant layer 20 to the distance L from the belt layer 7A located at the innermost side in the tire radial direction to the sealant layer 20 satisfies the relationship S / L≧0.3. By making the thickness S of the sealant layer 20 sufficiently large with respect to the distance L, good puncture sealing performance can be ensured. If the ratio S / L is less than 0.3, the puncture sealing performance will decrease.

[0041] FIG. 6 shows a pneumatic tire according to another embodiment of the present invention. In FIG. 6, a sound-absorbing material 40 is installed along the tire circumferential direction on the inner side in the tire radial direction of the sealant layer 20. The sound-absorbing material 40 is composed of a porous material having closed cells and has predetermined sound-absorbing characteristics based on its porous structure. It is preferable to use foamed polyurethane as the porous material of the sound-absorbing material 40. The sound-absorbing material 40 is adhered onto the sealant layer 20 based on the adhesiveness of the sealant layer 20 after the formation of the sealant layer 20. In this case, while obtaining the sound-absorbing effect based on the sound-absorbing material 20, it is possible to prevent foreign substances from adhering to the sealant layer 20. In particular, when the sealant of the sealant layer 20 is composed of a silicone-based composition, since the sound-absorbing material 40 is installed with respect to the sealant layer 20 applied at a low temperature, damage to the sound-absorbing material 40 can be avoided and its sound-absorbing effect can be maintained well.

Example

[0042] In a pneumatic tire having a tire size of 255 / 45R19 and including a tread portion, a pair of sidewall portions, and a pair of bead portions, tires of Comparative Examples 1 to 2 and Examples 1 to 7 were manufactured in which the presence or absence of a sealant layer and the physical properties of the sealant layer (peak value of tanδ, peak temperature of tanδ, tanδ at 100°C, loss shear elastic modulus G" at 100°C) were varied as shown in Table 1. The thickness of the tread rubber layer was 8 mm, the thickness of the sealant layer was 3 mm, and the width of the sealant layer was 190 mm.

[0043] Regarding these test tires, road noise, rolling resistance, puncture sealing performance, and flow resistance were evaluated by the following test methods, and the results are also shown in Table 1.

[0044] Road noise: Each test tire was assembled onto a wheel with a rim size of 19×8.5J and mounted on a test vehicle with a displacement of 2400 cc. The air pressure was set to 210 kPa, the load was set to 100% of the maximum load capacity, and the speed was set to 60 km / h. The road noise was measured when driving on a paved road. The evaluation results were shown as an index with the reciprocal of the measured value, with Comparative Example 1 set to 100. The larger this index value, the smaller the road noise.

[0045] Rolling resistance: Each test tire was assembled onto a wheel with a rim size of 19×8.5J and mounted on a rolling resistance tester. The air pressure was set to 210 kPa, and the rolling resistance was measured in accordance with JIS-D4234. The evaluation results were shown as an index with the reciprocal of the measured value, with Comparative Example 1 set to 100. The larger this index value, the smaller the rolling resistance.

[0046] Puncture sealing performance: Each test tire was assembled onto a wheel with a rim size of 19×8.5J, and the initial air pressure was set to 230 kPa. A nail with a diameter of 4.0 mm was driven into the tread part, and the tire was left for 1 hour with the nail pulled out, and then the air pressure was measured again. The evaluation results were indicated as "〇" when the air pressure was 200 kPa or more, "△" when the air pressure was 150 kPa or more and less than 200 kPa, and "×" when the air pressure was less than 150 kPa.

[0047] Resistance to flow: Each test tire was assembled onto a wheel with a rim size of 19×8.5J and mounted on an indoor drum tester (drum diameter 1707 mm). The air pressure was set to 230 kPa, the load was set to 100% of the maximum load capacity, and the speed was set to 200 km / h. After a 1-hour running test, the degree of flow of the sealant was confirmed. The evaluation results were indicated as "○" when there was no flow, "△" when there was flow (less than 1 / 4 of the whole), and "×" when there was flow (1 / 4 or more of the whole).

[0048]

Table 1

[0049] As can be seen from Table 1, in comparison with Comparative Example 1, the tires of Examples 1 to 7 were able to reduce road noise by attenuating vibrations during running without deteriorating rolling resistance. On the other hand, in the tire of Comparative Example 2, since the peak temperature of tanδ of the sealant layer was not appropriate, the effect of reducing road noise was insufficient.

[0050] The present disclosure includes the following inventions [1] to [8]. Invention [1] is a pneumatic tire including a tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the tire radial direction inner side of these sidewall portions, a sealant layer is formed on the inner surface of the tire in the tread portion, the peak temperature of tanδ of the sealant layer is in the range of -120°C to -20°C, and the peak value of tanδ of the sealant layer is 1.5 or more. Invention [2] is the pneumatic tire according to Invention [1], wherein the peak temperature of tanδ of the sealant layer is in the range of -90°C to -60°C. Invention [3] is the pneumatic tire according to Invention [1] or [2], wherein tanδ of the sealant layer at 100°C is in the range of 0.2 to 0.8. Invention [4] is the pneumatic tire according to any one of Inventions [1] to [3], wherein the loss shear elastic modulus G" of the sealant layer at 100°C is 5 kPa or less. Invention [5] includes a plurality of belt layers embedded in the tread portion, including belt cords inclined with respect to the tire circumferential direction and arranged so that the belt cords cross each other between layers, the plurality of belt layers including a first belt layer located on the innermost side in the tire radial direction and a second belt layer located on the outermost side in the tire radial direction, When a point that is 0.1Wb away from the end of the second belt layer toward the inner side in the tire width direction with respect to the width Wb of the second belt layer is defined as P1, and a point where a straight line extending in the tire radial direction passing through the point P1 intersects the inner surface of the tire is defined as P2, the pneumatic tire according to any one of inventions [1] to [4], characterized in that the end of the sealant layer is disposed on the outer side in the tire width direction with respect to the point P2. The invention [6] is a pneumatic tire according to any one of inventions [1] to [5], characterized in that the thickness of the sealant layer is in the range of 2.0 mm to 5.0 mm. The invention [7] is a pneumatic tire according to any one of inventions [1] to [6], characterized in that the sealant is composed of a silicone-based composition. The invention [8] is a pneumatic tire according to the invention [7], characterized in that the silicone-based composition is a two-component curable silicone.

Explanation of reference numerals

[0051] 1 Tread portion 2 Sidewall portion 3 Bead portion 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt cover layer 10 Inner surface of tire 20 Sealant layer

Claims

1. In a pneumatic tire having a tread portion extending in the tire circumferential direction and forming an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the inner side in the tire radial direction of these sidewall portions, a sealant layer is formed on the inner surface of the tire in the tread portion, the peak temperature of tanδ of the sealant layer is in the range of -120°C to -20°C, and the peak value of tanδ of the sealant layer is 1.5 or more. A pneumatic tire characterized by that.

2. The pneumatic tire according to claim 1, wherein the peak temperature of tanδ of the sealant layer is in the range of -90°C to -60°C.

3. The pneumatic tire according to claim 1 or 2, wherein tanδ of the sealant layer at 100°C is in the range of 0.2 to 0.

8.

4. The pneumatic tire according to claim 1 or 2, wherein the loss shear elastic modulus G" of the sealant layer at 100°C is 5 kPa or less.

5. In the tread portion, a plurality of belt layers including belt cords inclined with respect to the tire circumferential direction and arranged so that the belt cords cross each other between layers are embedded, and the plurality of belt layers include a first belt layer located on the innermost side in the tire radial direction and a second belt layer located on the outermost side in the tire radial direction. When a point 0.1Wb away from the end of the second belt layer toward the inner side in the tire width direction with respect to the width Wb of the second belt layer is defined as P1, and a point where a straight line extending in the tire radial direction passing through the point P1 intersects the inner surface of the tire is defined as P2, the end of the sealant layer is disposed on the outer side in the tire width direction than the point P2. The pneumatic tire according to claim 1 or 2, characterized by that.

6. The pneumatic tire according to claim 1 or 2, wherein the thickness of the sealant layer is in the range of 2.0 mm to 5.0 mm.

7. The pneumatic tire according to claim 1 or 2, wherein the sealant is composed of a silicone-based composition.

8. The pneumatic tire according to claim 7, wherein the silicone-based composition is a two-component curable silicone.

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