Pneumatic tire

Abstract

To provide a pneumatic tire which enables reduction of electric resistance when a sealant layer is provided on a tire inner surface.SOLUTION: A pneumatic tire includes: a tread part 1 extending in a tire circumferential direction and forming an annular form; a pair of side wall parts 2 disposed at both sides of the tread part 1; and a pair of bead parts 3 disposed at the inner side in a tire radial direction of the side wall parts 2. Further, a carcass layer 4 is installed between the pair of bead parts 3, 3, and a belt layer 7 is buried at the outer periphery side of the carcass layer 4 in the tread part 1. A sealant layer 20 is disposed on a tire inner surface 10 in the tread part 1 and a powder 15 containing conductive particles is applied to at least a part of the tire inner surface 10 in which the sealant layer 20 is not disposed. A conductive member 16 is arranged along the carcass layer 4 so as to overlap with both of the belt layer 7 and the area to which the powder 15 containing the conductive particles is applied.SELECTED DRAWING: Figure 3

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 electrical resistance when providing a sealant layer on the inner surface of the tire.

Background Art

[0002] In recent years, as a method for reducing the fuel consumption of pneumatic tires, silica has been compounded into the rubber composition used in the tread portion and the sidewall portion to suppress the rolling resistance of the tire. However, since silica has insulating properties, when the silica content of the tread rubber or the sidewall rubber increases, the electrical resistance of the tire increases and the antistatic function of the tire deteriorates. When the antistatic function of the tire deteriorates, static electricity generated during the running of the vehicle is likely to accumulate, so that radio wave interference such as radio noise is likely to occur.

[0003] In the pneumatic tire as described above, when the mold release agent applied to the inner surface of the tire contains conductive particles, the layer containing the conductive particles functions as a conductive path and also contributes to the reduction of the electrical resistance of the tire.

[0004] On the other hand, 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 a pneumatic tire. In such a pneumatic tire, when a foreign object such as a nail pierces the tread portion, the sealant flows into the through hole, so that it is possible to suppress a decrease in air pressure and maintain running.

[0005] Conventionally, the sealant constituting the sealant layer is generally a rubber composition mainly composed of butyl rubber (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).

[0006] However, when attaching a sealant layer to the inner surface of a pneumatic tire, it is necessary to previously remove the mold release agent containing conductive particles applied to the inner surface of the tire, or the conductive particles are incorporated into the sealant, resulting in the layer containing conductive particles applied to the inner surface of the tire not functioning as an effective conductive path and the electrical resistance of the tire increasing.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] An object of the present invention is to provide a pneumatic tire that enables reduction of electrical resistance when providing a sealant layer on the inner surface of the tire.

Means for Solving the Problems

[0009] The pneumatic tire of the present invention for achieving the above object includes 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 radially inner side of the tire of these sidewall portions. A carcass layer is mounted between the pair of bead portions, and in the pneumatic tire in which a belt layer is embedded on the outer peripheral side of the carcass layer in the tread portion, While a sealant layer is disposed on the inner surface of the tire in the tread portion, a powder containing conductive particles is applied to at least a part of the region of the inner surface of the tire where the sealant layer is not disposed, and a conductive member is disposed along the carcass layer so as to overlap both the belt layer and the region where the powder containing conductive particles is applied.

Advantages of the Invention

[0010] In the present invention, while a sealant layer is disposed on the inner surface of the tire in the tread portion, a powder containing conductive particles is applied to at least a part of the region of the inner surface of the tire where the sealant layer is not disposed, and a conductive member is disposed along the carcass layer so as to overlap both the belt layer and the region where the powder containing conductive particles is applied. Thus, in a pneumatic tire provided with a sealant layer, since the belt layer, the conductive member, and the region where the powder containing conductive particles is applied form a series of conductive paths, the electrical resistance of the tire can be reduced.

[0011] In the present invention, it is preferable that the shortest distance between the conductive member and the belt layer and the shortest distance between the conductive member and the powder containing conductive particles are each 3 mm or less. By the shortest distance being 3 mm or less, an effective conductive path can be formed.

[0012] In the present invention, it is preferable that the width Ws of the sealant layer satisfies the relationship Ws ≧ W - 10 mm with respect to the width Wb of the belt layer located at the innermost side in the tire radial direction. By the width Ws of the sealant layer satisfying the above relationship, good puncture sealing performance can be ensured.

[0013] In the present invention, it is preferable that the conductive member is composed of a rubber composition. When the conductive member is composed of a rubber composition in this way, the conductive member can be handled in the same manner as a normal tire component, so that the productivity of the tire is improved.

[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 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 the two components are mixed, it can be applied even at low temperatures. Also, in the case of a two-component curable silicone, since the mold release agent applied to the inner surface of the tire is easily incorporated into the sealant during the curing process, peeling of the sealant layer from the inner surface of the tire can be suppressed.

[0015] In the present invention, it is preferable that the sealant contains a powder containing conductive particles. By the sealant containing a powder containing conductive particles, a function as a conductive path can also be imparted to the sealant layer.

[0016] In the present invention, it is preferable that the distance in the tire width direction between the center position of the sealant layer in the tire width direction and the tire equator is 10 mm or less. By reducing the distance in the tire width direction between the center position of the sealant layer in the tire width direction and the tire equator, the tire balance can be improved.

[0017] In the present invention, it is preferable that a sound-absorbing material is installed along the tire circumferential direction on the inner side in the tire radial direction of the sealant layer. In this case, while obtaining the sound-absorbing effect based on the sound-absorbing material, it is possible to prevent foreign matter from adhering to the sealant layer.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0019] Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIGS. 1 to 3 show pneumatic tires according to embodiments of the present invention.

[0020] 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.

[0021] 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 back from the inner side to the outer side of the tire 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.

[0022] On the other hand, 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. 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.

[0023] On the outer peripheral side of the belt layer 7, 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 for the purpose of improving high-speed durability. It is desirable that this belt cover layer 8 has a jointless structure formed by continuously winding a strip material, which is obtained by covering at least one reinforcing cord with rubber, substantially at 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.

[0024] In addition, the above-described tire internal structure shows a typical example in a pneumatic tire, but is not limited thereto. Further, an inner liner layer 9 (air permeation prevention layer) is arranged along the carcass layer 4 inside the carcass layer 4. In the tread portion 1, various grooves including a plurality of main grooves 11 extending in the tire circumferential direction are formed. Further, a tread rubber layer R1 is arranged outside the belt cover layer 8 in the tread portion 1, a sidewall rubber layer R2 is arranged outside the carcass layer 4 in the sidewall portion 2, and a rim cushion rubber layer R3 is arranged outside the carcass layer 4 in the bead portion 3.

[0025] In the above pneumatic tire, as shown in FIGS. 1 to 3, a sealant layer 20 is arranged on the tire inner surface 10 in the tread portion 1 so as to be continuous in the tire circumferential direction. On the other hand, a powder 15 containing conductive particles is applied to at least a part of the region of the tire inner surface 10 where the sealant layer 20 is not arranged, and a conductive member 16 is arranged along the carcass layer 4 so as to overlap both the belt layer 7 and the region where the powder 15 containing conductive particles is applied.

[0026] The center position of the sealant layer 20 in the tire width direction preferably coincides with the tire equator CL, but the center position may be shifted toward either one side in the tire width direction from the tire equator CL. 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 CL 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 a 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.

[0027] The width Ws of the sealant layer 20 preferably satisfies the relationship of Ws≧W - 10 mm with respect to the width Wb of the belt layer 7A located at the innermost side in the tire radial direction. By the width Ws of the sealant layer 20 satisfying the above relationship, good puncture sealing performance can be ensured. Here, if the width Ws of the sealant layer 20 is smaller than [W - 10 mm], the puncture sealing performance will deteriorate.

[0028] The powder 15 containing conductive particles needs to be applied to at least a part of the region of the tire inner surface 10 where the sealant layer 20 is not disposed, but it is preferable that the powder is applied over the entire area from the end of the sealant layer 20 to the bead toe of the bead portion 3. Further, the powder 15 containing conductive particles may be interposed between the sealant layer 20 and the tire inner surface 10. Examples of the conductive particles contained in the powder 15 include carbon black and alumina. The powder 15 may contain talc, mica, etc. in addition to the conductive particles.

[0029] The conductive member 16 is preferably composed of a rubber composition. When the conductive member 16 is composed of a rubber composition, the conductive member 16 can be handled in the same manner as ordinary tire constituent members, so that the productivity of the tire is good. The volume resistivity of the conductive member 16 made of a rubber composition is 1×10 8It is preferably below Ω·cm. The volume resistivity is measured in accordance with the provisions of JIS-K6271-1 or 2. Generally, when the volume resistivity is 1×10 8 Ω·cm or less, it can be said that the member has conductivity capable of suppressing the charging of static electricity. The volume resistivity of the conductive member 16 made of the rubber composition can be arbitrarily adjusted based on the blending amount of a conductive filler such as carbon black. The conductive member 16 may be a conductive linear body such as a metal fiber, a carbon fiber, or a conductive coating yarn. Also in this case, the volume resistivity of the conductive member 16 made of the conductive linear body is preferably 1×10 8 Ω·cm or less. In particular, it is desirable that the volume resistivity of the conductive member 16 is 1×10 7 Ω·cm or less. Further, the overlap width W1 between the conductive member 16 and the belt layer 7 and the overlap width W2 between the conductive member 16 and the region coated with the powder 15 containing conductive particles are each preferably 10 mm or more (see Fig. 3).

[0030] According to the pneumatic tire described above, while the sealant layer 20 is disposed on the inner surface 10 of the tread portion 1 of the tire, the powder 15 containing conductive particles is applied to at least a part of the region of the inner surface 10 of the tire where the sealant layer 20 is not disposed, and the conductive member 16 is disposed along the carcass layer 4 so as to overlap both the belt layer 7 and the region coated with the powder 15 containing conductive particles. Thus, in the pneumatic tire provided with the sealant layer 20, the region of the belt layer 7, the conductive member 16, and the powder 15 containing conductive particles forms a series of conductive paths, so that the electrical resistance of the tire can be reduced. In particular, in a pneumatic tire in which the volume resistivity of the sidewall rubber layer R2 is 1×10 9 Ω·cm or more, a remarkable effect of reducing the electrical resistance can be obtained.

[0031] In the pneumatic tire described above, it is preferable that the shortest distance between the conductive member 16 and the belt layer 7 and the shortest distance between the conductive member 16 and the powder 15 containing conductive particles are each 3 mm or less. That is, even if the conductive member 16 and the belt layer 7 do not directly contact each other, or even if the conductive member 16 and the powder 15 containing conductive particles do not directly contact each other, an effective conductive path can be formed by setting the shortest distance to 3 mm or less.

[0032] In the pneumatic tire described above, the sealant of the sealant layer 20 may contain the powder 15 containing conductive particles. By the sealant of the sealant layer 20 containing the powder 15 containing conductive particles, the sealant layer 20 can also be imparted with a function as a conductive path.

[0033] FIG. 4 and FIG. 5 each show a modified example of the pneumatic tire of FIG. 3. In FIG. 3, the conductive member 16 is disposed between the edge portion of the belt layer 7 and the carcass layer 4. That is, by optimizing the volume resistivity of the so-called belt edge cushion rubber layer, it is used as the conductive member 16. In contrast, in the example of FIG. 4, the conductive member 16 is disposed between the carcass layer 4 and the inner liner layer 9, and this conductive member 16 overlaps with the region where the belt layer 7 and the powder 15 containing conductive particles are applied. In the example of FIG. 5, the conductive member 16 is disposed inside the inner liner layer 9, and this conductive member 16 overlaps with the region where the belt layer 7 and the powder 15 containing conductive particles are applied.

[0034] The pneumatic tire described above can be manufactured by the following method. First, as described above, a pneumatic tire having a tread portion 1, a pair of sidewall portions 2, and a pair of bead portions 3 is provided. A carcass layer 4 is mounted between the pair of bead portions 3, 3, and a belt layer 7 is embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. At the same time, a pneumatic tire provided with a conductive member 16 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. On the other hand, a powder 15 containing conductive particles is applied to at least a part of the region of the inner surface 10 of the tire where the sealant layer 20 is not disposed. Such a powder 15 containing conductive particles can be sprayed onto the inner surface 10 of the tire before or after vulcanization of the tire, or may be sprayed onto the inner surface 10 of the tire after the formation of the sealant layer 20.

[0035] FIG. 6 shows a specific manufacturing method of the pneumatic tire of FIG. 1, and FIG. 7 shows a sealant layer formed on the inner surface of the tire in the tread portion. In FIG. 6, the sealant extruding device 31 is configured to mix the sealants supplied from the pumps 32, 33 and continuously discharge 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. 7). 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 such a spiral shape is integrated to form a sealant layer 20.

[0036] 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 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 21 are easily adapted to each other in the curing reaction process of the silicone-based composition, and the integrity of the circumferential portions of the sealant strip 21 is improved. Therefore, the sealing performance of the sealant layer 20 can be improved. Further, since the integrity of the circumferential portions of the sealant strip 21 is good, it is 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, which 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, it has the advantages of excellent weather resistance and low temperature dependence of physical properties.

[0037] 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 35°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.

[0038] 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 low temperatures. In particular, it is preferable that the two-component curable silicone has a period until complete curing of 5 days or more.

[0039] 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.

[0040] In the above pneumatic tire, it is preferable that the glass transition temperature of the sealant of the sealant layer 20 is in the range of -120°C to -40°C. By using a sealant having a low glass transition temperature, it is possible to ensure good puncture sealing performance in a low-temperature environment. If the glass transition temperature of the sealant is higher than -40°C, the puncture sealing performance in a low-temperature environment deteriorates.

[0041] 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 suppress the deterioration of rolling resistance due to an increase in tire weight, and to suppress the uneven distribution of the sealant layer 20 caused by the flow of the sealant. Here, if the thickness S of the sealant layer 20 is less than 2.0 mm, the puncture sealing performance will deteriorate. Conversely, if it is greater than 5.0 mm, the rolling resistance will deteriorate due to an increase in tire weight, and there is a risk of uneven distribution of the sealant layer 20 due to the flow of the sealant. 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 taking CT scans of the tire meridian cross-section at 8 locations on the tire circumference, and at 5 points in each of the captured images, namely, 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, measuring the thickness of the sealant layer 20, and calculating from the measured values at a total of 40 points.

[0042] In the above pneumatic tire, as shown in Fig. 2, when a belt layer 7 (7A, 7B) including belt cords inclined in the tire circumferential direction is embedded in the tread portion 1, at all locations of the belt layer 7A located innermost in the tire radial direction, it is preferable that the distance (shortest distance) L from the 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 belt layer 7A, so that good puncture sealing performance can be ensured. If there is a portion where the distance L from the belt layer 7A to the sealant layer 20 is greater than 10 mm, the puncture sealing performance in that portion may become insufficient.

[0043] 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 innermost 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 deteriorate.

[0044] FIG. 8 shows a pneumatic tire according to another embodiment of the present invention. In FIG. 8, 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 the porous structure thereof. 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

[0045] In a pneumatic tire having a tire size of 255 / 45R19, including a tread portion, a pair of sidewall portions, and a pair of bead portions, with a carcass layer mounted between the pair of bead portions and a belt layer embedded on the outer peripheral side of the carcass layer in the tread portion, while a sealant layer is formed on the inner surface of the tire in the tread portion, tires of Comparative Examples 1 to 3 and Examples 1 to 8 were manufactured with different presence or absence of powder containing conductive particles applied to the inner surface of the tire and a conductive member. In Comparative Examples 1 to 3 and Examples 1 to 8, the volume resistivity of the sidewall rubber layer is 1×10 9 Ω·cm, its tanδ(60°C) is 0.15, the maximum width of the belt layer is 210 mm, the width of the sealant layer is 210 mm, the thickness of the sealant layer is 3 mm, and the sealant of the sealant layer is a silicone-based composition (SST-2650 manufactured by Dow).

[0046] The specifications of the conductive member (position, material, volume resistivity, amount of overlap with the belt layer, shortest distance from the belt layer, amount of overlap with the powder region, shortest distance from the powder), and the method of applying the powder containing conductive particles to the inner surface of the tire are as shown in Table 1. As the conductive member, a diene rubber composition (A), carbon fiber (B), or conductive coated yarn (C) was used. The formulation of the coating liquid used when applying the powder containing conductive particles to the inner surface of the tire is as shown in Table 2. When the powder containing conductive particles was applied before or after vulcanization, the powder containing conductive particles was applied over the entire inner surface of the tire. On the other hand, when the powder containing conductive particles was applied after sealant application, the powder containing conductive particles was applied over the entire inner surface of the tire where the sealant layer was not disposed.

[0047] For these test tires, the electrical resistance was measured by the following test method, and the results are shown together with Table 1.

[0048] Electrical resistance: Each test tire was assembled on a wheel with a rim size of 19×8.5J, the air pressure was set to 200 kPa, and the load was set to 80% of the maximum load capacity. The electrical resistance between the wheel and the metal plate was measured while the tire was placed on the metal plate.

[0049] [Table 1]

[0050] [Table 2]

[0051] As can be seen from Table 1, in the tires of Examples 1 to 8, a reduction effect in electrical resistance was recognized because the region where the belt layer, the conductive member, and the powder containing conductive particles were applied formed a series of conductive paths. On the other hand, in the tires of Comparative Examples 1 to 3, since a series of conductive paths as described above were not formed, the electrical resistance was high.

[0052] This disclosure includes the following inventions [1] to [9]. The invention [1] comprises 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 carcass layer is mounted between the pair of bead portions, and in a pneumatic tire in which a belt layer is embedded on the outer peripheral side of the carcass layer in the tread portion, while a sealant layer is disposed on the inner surface of the tire in the tread portion, a powder containing conductive particles is applied to at least a part of the region of the inner surface of the tire where the sealant layer is not disposed, and a conductive member is disposed along the carcass layer so as to overlap both the belt layer and the region where the powder containing conductive particles is applied. It is a pneumatic tire characterized by this. The invention [2] is the pneumatic tire according to the invention [1], characterized in that the shortest distance between the conductive member and the belt layer and the shortest distance between the conductive member and the powder containing conductive particles are each 3 mm or less. The invention [3] is the pneumatic tire according to the invention [1] or [2], characterized in that the width Ws of the sealant layer satisfies the relationship Ws ≧ W - 10 mm with respect to the width Wb of the belt layer located innermost in the tire radial direction. The invention [4] is the pneumatic tire according to any one of the inventions [1] to [3], characterized in that the conductive member is composed of a rubber composition. The invention [5] is the pneumatic tire according to any one of the inventions [1] to [4], characterized in that the sealant is composed of a silicone-based composition. The invention [6] is the pneumatic tire according to the invention [5], characterized in that the silicone-based composition is a two-component curable silicone. The invention [7] is the pneumatic tire according to any one of the inventions [1] to [6], characterized in that the sealant contains a powder containing conductive particles. The invention [8] is the pneumatic tire according to any one of the inventions [1] to [7], characterized in that the distance in the tire width direction between the center position of the sealant layer in the tire width direction and the tire equator is 10 mm or less. The invention [9] is a pneumatic tire according to any one of inventions [1] to [8], characterized in that a sound absorbing material is installed along the tire circumferential direction on the inner side in the tire radial direction of the sealant layer.

Explanation of reference numerals

[0053] 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 9 Inner liner layer 10 Tire inner surface 15 Powder containing conductive particles 16 Conductive member 20 Sealant layer 21 Strip material of sealant 40 Sound absorbing material

Claims

1. An inflatable tire comprising a tread portion extending in the circumferential direction of the tire 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 inner side in the tire radial direction of these sidewall portions, a carcass layer is mounted between the pair of bead portions, and a belt layer is embedded on the outer peripheral side of the carcass layer in the tread portion, wherein a sealant layer is disposed on the inner surface of the tire in the tread portion, while a powder containing conductive particles is applied to at least a part of the region of the inner surface of the tire where the sealant layer is not disposed, and a conductive member is disposed along the carcass layer so as to overlap both the belt layer and the region where the powder containing conductive particles is applied. The inflatable tire is characterized by this.

2. The inflatable tire according to claim 1, wherein the shortest distance between the conductive member and the belt layer and the shortest distance between the conductive member and the powder containing conductive particles are each 3 mm or less.

3. The inflatable tire according to claim 1 or 2, wherein the width Ws of the sealant layer satisfies the relationship of Ws ≧ W - 10 mm with respect to the width Wb of the belt layer located at the innermost side in the tire radial direction.

4. The inflatable tire according to claim 1 or 2, wherein the conductive member is composed of a rubber composition.

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

6. The inflatable tire according to claim 5, wherein the silicone-based composition is a two-component curable silicone.

7. The inflatable tire according to claim 1 or 2, wherein the sealant contains a powder containing conductive particles.

8. The inflatable tire according to claim 1 or 2, wherein the distance in the tire width direction between the center position of the sealant layer in the tire width direction and the tire equator is 10 mm or less.

9. The inflatable tire according to claim 1 or 2, wherein a sound-absorbing material is installed along the tire circumferential direction on the inner side in the tire radial direction of the sealant layer.

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