Pneumatic tire

Abstract

To provide a pneumatic tire which allows for improvement of durability of a transponder while securing durability of the tire.SOLUTION: In a pneumatic tire including a tread part 1 annularly extending in a tire circumferential direction, a pair of sidewall parts 2 provided in both sides of the tread part 1, and a pair of bead parts 3 provided in an inside of the sidewall part 2 in a tire diameter direction, a transponder 20 is buried in the tire, the transponder 20 is coated by a coating layer 23, a modulus M50(0°C) in 50% deformation at 0°C of the coating layer 23 is in a range of 0.5 MPa-2.0 MPa, and a modulus M50(-20°C) in 50% deformation at -20°C and the modulus M50(0°C) in 50% deformation at 0°C of the coating layer satisfies the relation of 1.0<M50(-20°C) / M50(0°C)≤2.5.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a pneumatic tire in which a transponder covered with a coating layer is embedded, and more particularly to a pneumatic tire that enables improvement of the durability of the transponder while ensuring the durability of the tire.

Background Art

[0002] In pneumatic tires, it has been proposed to embed an RFID tag (transponder) in the tire (see, for example, Patent Document 1). When embedding a transponder in a tire, if the physical properties of the coating layer for protecting the transponder are inappropriate, the durability of the tire and the transponder cannot be sufficiently ensured. For example, if the temperature dependence of the modulus of the coating layer in the low temperature range is too small, stress concentration occurs near the edge of the coating layer when the temperature of the tire rises during driving in a low temperature environment, and peeling is likely to occur between the coating layer and the surrounding members, leading to tire damage. On the other hand, if the temperature dependence of the modulus of the coating layer in the low temperature range is too large, the coating layer softens when the temperature of the tire rises during driving in a low temperature environment, and the protective effect of the transponder is impaired.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a pneumatic tire that enables improvement of the durability of the transponder while ensuring the durability of the tire.

Means for Solving the Problems

[0005] In order to achieve the above object, the pneumatic tire of the present invention 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 inner side in the tire radial direction of these sidewall portions. In the pneumatic tire, a transponder is embedded in the tire, the transponder is covered with a coating layer, the 50% modulus of deformation M50(0°C) of the coating layer at 0°C is in the range of 0.5 MPa to 2.0 MPa, and the 50% modulus of deformation M50(-20°C) of the coating layer at -20°C and the 50% modulus of deformation M50(0°C) of the coating layer at 0°C satisfy the relationship of 1.0 < M50(-20°C) / M50(0°C) ≤ 2.5. and the storage elastic modulus E'c(-20°C) of the coating layer is in the range of 3 MPa to 17 MPa, the transponder is embedded outside the tire width direction from the carcass layer, and the storage elastic modulus E'c(-20°C) of the coating layer and the storage elastic modulus at -20°C E'out(-20°C) in the rubber member with the largest storage elastic modulus at 20°C among the rubber members located outside the tire width direction from the transponder satisfy the relationship of 0.1 ≦ E'c(-20°C) / E'out(-20°C) ≦ 1.5, the center of the transponder is arranged at a distance of 10 mm or more in the tire circumferential direction from the splice portion of the tire constituent member It is characterized by the above.

Effect of the Invention

[0006] In the present invention, the transponder is covered with a coating layer, the 50% modulus of deformation M50(0°C) of the coating layer at 0°C is set within the above range, and the 50% modulus of deformation M50(-20°C) of the coating layer at -20°C and the 50% modulus of deformation M50(0°C) of the coating layer at 0°C satisfy the above relational expression. Therefore, in a low-temperature environment, while avoiding stress concentration near the edge of the coating layer when the tire temperature rises, it is possible to fully exert the protective effect of the coating layer on the transponder. Thereby, while ensuring the durability of the tire, the durability of the transponder can be improved.

[0007] In the pneumatic tire of the present invention, it is preferable that the relative permittivity of the coating layer is 7 or less. Thereby, the radio wave transmissivity of the transponder can be ensured, and the communication performance of the transponder can be improved.

[0008] It is preferable that the storage elastic modulus E'c(-20°C) of the coating layer at -20°C is in the range of 3 MPa to 17 MPa. Thereby, in a low-temperature environment, while ensuring the durability of the tire, the durability of the transponder can be effectively improved.

[0009] The transponder is embedded outside the tire width direction from the carcass layer, and the storage elastic modulus E'c(-20°C) of the coating layer and the storage elastic modulus E'out(-20°C) at -20°C of the rubber member with the largest storage elastic modulus at 20°C among the rubber members located outside the tire width direction from the transponder satisfy the relationship of 0.1 ≦ E'c(-20°C) / E'out(-20°C) ≦ 1.5. Thus, in a low-temperature environment, while ensuring the durability of the tire, the durability of the transponder can be effectively improved.

[0010] The coating layer preferably consists of rubber or elastomer and 20 phr or more of a white filler. Thereby, the relative permittivity of the coating layer can be made relatively low, and the communication performance of the transponder can be effectively improved.

[0011] The white filler preferably contains 20 phr to 55 phr of calcium carbonate. Thereby, the relative permittivity of the coating layer can be made relatively low, and the communication performance of the transponder can be effectively improved.

[0012] The center of the transponder is preferably arranged at a distance of 10 mm or more in the tire circumferential direction from the splice portion of the tire constituent member. Thereby, the durability of the tire can be effectively improved.

[0013] The transponder is preferably arranged between the position 15 mm radially outside the tire from the upper end of the bead core of the bead portion and the maximum tire width position. Thereby, since the transponder is arranged in a region where the stress amplitude during running is small, the durability of the transponder can be effectively improved, and furthermore, the durability of the tire is not reduced.

[0014] The distance between the cross-sectional center of the transponder and the tire surface is preferably 1 mm or more. Thereby, the durability of the tire can be effectively improved, and the cut resistance of the tire can be improved.

[0015] The thickness of the coating layer is preferably 0.5 mm to 3.0 mm. Thereby, the communication performance of the transponder can be effectively improved without causing unevenness on the tire surface.

[0016] The transponder has an IC substrate for storing data and an antenna for transmitting and receiving data, and the antenna is preferably spiral. Thereby, it can follow the deformation of the tire during running, and the durability of the transponder can be improved.

[0017] In the present invention, the modulus at 50% deformation is the tensile stress at 50% elongation measured under the conditions of each specified temperature and a tensile speed of 500 mm / min using a dumbbell-shaped test piece of No. 3 according to JIS-K6251. However, when a dumbbell-shaped test piece of No. 3 cannot be sampled from the tire, a test piece having a different shape may be used. Further, the storage elastic modulus E' is measured under the conditions of each specified temperature, a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of ±2% in the tensile deformation mode using a viscoelastic spectrometer according to JIS-K6394.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Best Mode 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 4 show a pneumatic tire according to an embodiment 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 disposed on both sides of the tread portion 1, and a pair of bead portions 3 disposed on the radially inner side of these sidewall portions 2 in the tire diameter direction.

[0021] At least one layer (one layer in FIG. 1) of carcass layer 4 formed by arranging a plurality of carcass cords in the radial direction is mounted between the pair of bead portions 3. The carcass layer 4 is covered with rubber. As the carcass cords constituting the carcass layer 4, organic fiber cords such as nylon and polyester are preferably used. An annular bead core 5 is embedded in each bead portion 3, and a bead filler 6 made of a rubber composition having a triangular cross-section is disposed on the outer circumference of the bead core 5.

[0022] On the other hand, a plurality of layers (two layers in FIG. 1) of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. The belt layer 7 includes a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to cross each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set in the range of, for example, 10° to 40°. As the reinforcing cords of the belt layer 7, steel cords are preferably used.

[0023] On the outer peripheral side of the tire of the belt layer 7, for the purpose of improving high-speed durability, at least one layer (two layers in FIG. 1) of 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. In FIG. 1, the belt cover layer 8 located on the inner side in the tire radial direction constitutes a full cover that covers the entire width of the belt layer 7, and the belt cover layer 8 located on the outer side in the tire radial direction constitutes an edge cover layer that covers only the end portion of the belt layer 7. As the reinforcing cords of the belt cover layer 8, organic fiber cords such as nylon and aramid are preferably used.

[0024] In the above pneumatic tire, both end portions 4e of the carcass layer 4 are folded from the inner side to the outer side of the tire around each bead core 5 and are arranged so as to wrap the bead core 5 and the bead filler 6. The carcass layer 4 includes a main body portion 4A which is a portion extending from the tread portion 1 through each sidewall portion 2 to each bead portion 3, and a winding-up portion 4B which is a portion wound around the bead core 5 in each bead portion 3 and extends toward each sidewall portion 2 side.

[0025] Also, an inner liner layer 9 is arranged on the inner surface of the tire along the carcass layer 4. A cap tread rubber layer 11 is arranged on the tread portion 1, a sidewall rubber layer 12 is arranged on the sidewall portion 2, and a rim cushion rubber layer 13 is arranged on the bead portion 3.

[0026] Also, in the above pneumatic tire, a transponder 20 is embedded in a portion outside the carcass layer 4 in the tire width direction. The transponder 20 extends along the tire circumferential direction. The transponder 20 may be arranged to be inclined in the range of -10° to 10° with respect to the tire circumferential direction. Also, as shown in FIG. 4, the transponder 20 is covered by a covering layer 23. This covering layer 23 covers the entire transponder 20 so as to sandwich both the front and back surfaces of the transponder 20. The covering layer 23 may be made of rubber having the same physical properties as the rubber constituting the sidewall rubber layer 12 or the rim cushion rubber layer 13, or may be made of rubber having different physical properties.

[0027] As the transponder 20, for example, an RFID (Radio Frequency Identification) tag can be used. As shown in FIGS. 5(a) and 5(b), the transponder 20 has an IC substrate 21 for storing data and an antenna 22 for transmitting and receiving data in a non-contact manner. By using such a transponder 20, information regarding the tire can be written or read out in a timely manner, and the tire can be efficiently managed. Note that RFID is an automatic identification technology composed of a reader / writer having an antenna and a controller, and an ID tag having an IC substrate and an antenna, and capable of communicating data by a wireless method.

[0028] The overall shape of the transponder 20 is not particularly limited, and for example, columnar or plate-like ones as shown in FIGS. 5(a) and 5(b) can be used. In particular, when the columnar transponder 20 shown in FIG. 5(a) is used, it is suitable because it can follow the deformation of the tire in each direction. In this case, the antenna 22 of the transponder 20 protrudes from each of both ends of the IC substrate 21 and has a spiral shape. Thereby, it can follow the deformation of the tire during traveling, and the durability of the transponder 20 can be improved. Further, by appropriately changing the length of the antenna 22, communication performance can be ensured.

[0029] In the pneumatic tire configured as described above, the 50% modulus M50(0°C) at 0°C of the coating layer 23 covering the transponder 20 is set in the range of 0.5 MPa to 2.0 MPa. In particular, it is preferable that the 50% modulus M50(0°C) at 0°C of the coating layer 23 is in the range of 0.6 MPa to 1.3 MPa. Further, the 50% modulus M50(-20°C) at -20°C and the 50% modulus M50(0°C) at 0°C of the coating layer 23 satisfy the relationship of 1.0 < M50(-20°C) / M50(0°C) ≤ 2.5. In particular, it is preferable to satisfy the relationship of 1.1 ≤ M50(-20°C) / M50(0°C) ≤ 2.0.

[0030] In the pneumatic tire described above, the transponder 20 is covered by the covering layer 23, and the 50% modulus of deformation M50(0°C) of the covering layer 23 at 0°C is set within the above range. Therefore, in a low-temperature environment, while avoiding stress concentration near the edge of the covering layer 23 when the tire temperature rises, it is possible to fully exhibit the protective effect of the covering layer 23 on the transponder 20. Thereby, while ensuring the durability of the tire, the durability of the transponder 20 can be improved.

[0031] Here, if the 50% modulus of deformation M50(0°C) of the covering layer 23 at 0°C is lower than the lower limit value, the protective effect on the transponder 20 will decrease, and the transponder 20 will be more likely to be damaged. Conversely, if the 50% modulus of deformation M50(0°C) of the covering layer 23 at 0°C is higher than the upper limit value, stress concentration will occur near the edge of the covering layer 23 when the tire deforms, and peeling is likely to occur at the interface between the covering layer 23 and the rubber member adjacent to the covering layer 23.

[0032] Also, in the pneumatic tire described above, since the 50% modulus of deformation M50(-20°C) of the covering layer 23 at -20°C and the 50% modulus of deformation M50(0°C) of the covering layer 23 at 0°C satisfy the above relational expression, in a low-temperature environment, while avoiding stress concentration near the edge of the covering layer 23 when the tire temperature rises, it is possible to fully exhibit the protective effect of the covering layer 23 on the transponder 20 at high temperatures. Thereby, while ensuring the durability of the tire, the durability of the transponder 20 can be improved.

[0033] Here, if the value of M50(-20°C) / M50(0°C) of the coating layer 23 is lower than the lower limit value and the temperature dependence of the modulus of the coating layer 23 in the low temperature range is too small, when the temperature of the tire rises during driving in a low temperature environment, stress concentration occurs near the edge of the coating layer 23, and peeling is likely to occur at the interface between the coating layer 23 and the rubber member adjacent to the coating layer 23, resulting in a decrease in the durability of the tire. Conversely, if the value of M50(-20°C) / M50(0°C) of the coating layer 23 is higher than the upper limit value and the temperature dependence of the modulus of the coating layer 23 in the low temperature range is too large, the coating layer 23 softens when the temperature of the tire rises during driving in a low temperature environment, and the protection effect of the transponder 20 decreases.

[0034] Furthermore, in the pneumatic tire described above, since the transponder 20 is embedded outside the carcass layer 4 in the tire width direction, there is no tire component that blocks radio waves during the communication of the transponder 20, and the communication performance of the transponder 20 can be ensured well. When the transponder 20 is embedded outside the carcass layer 4 in the tire width direction, the transponder 20 can be arranged between the turned-up portion 4B of the carcass layer 4 and the rim cushion rubber layer 13 or between the carcass layer 4 and the sidewall rubber layer 12. As another structure, it is also possible to arrange the transponder 20 between the turned-up portion 4B of the carcass layer 4 and the bead filler 6 or between the main body portion 4A of the carcass layer 4 and the bead filler 6.

[0035] In the pneumatic tire described above, it is preferable that the storage elastic modulus E'c(-20°C) of the coating layer 23 is in the range of 3 MPa to 17 MPa. By setting the physical properties of the coating layer 23 in this way, the durability of the transponder 20 can be effectively improved in a low temperature environment.

[0036] Here, if the storage elastic modulus E'c(-20°C) of the coating layer 23 at -20°C is lower than the lower limit value, the rigidity of the coating layer 23 becomes low and the protective property deteriorates. Conversely, if the storage elastic modulus E'c(-20°C) of the coating layer 23 at -20°C is higher than the upper limit value, the rigidity of the coating layer 23 becomes high, the coating layer 23 becomes brittle, and the coating layer 23 is likely to break, so the transponder 20 is likely to be damaged.

[0037] It is preferable that the storage elastic modulus E'c(-20°C) of the coating layer 23 at -20°C and the storage elastic modulus E'c(0°C) of the coating layer 23 at 0°C satisfy the relationship of 1.0 ≦ E'c(-20°C) / E'c(0°C) ≦ 1.5. By setting the physical properties of the coating layer 23 in this way, the temperature dependence of the coating layer 23 becomes low (the coating layer 23 is less likely to generate heat), so even when the temperature of the tire rises during high-speed driving, the coating layer 23 does not soften, and the durability of the transponder 20 can be effectively improved.

[0038] In the pneumatic tire described above, among the rubber members (the sidewall rubber layer 12 and the rim cushion rubber layer 13 in FIG. 1) located outside the tire width direction from the transponder 20, the rubber member with the largest storage elastic modulus E'out(20°C) at 20°C (hereinafter, may also be referred to as an external member) corresponds to the rim cushion rubber layer 13. Note that the coating layer 23 covering the transponder 20 is not included as the rubber member (external member) with the largest storage elastic modulus at 20°C.

[0039] And in the structure where the transponder 20 is embedded outside the carcass layer 4 in the tire width direction, it is preferable that the storage elastic modulus E'out(-20°C) of the external member at -20°C and the storage elastic modulus E'c(-20°C) of the coating layer 23 at -20°C satisfy the relationship of 0.1 ≦ E'c(-20°C) / E'out(-20°C) ≦ 1.5. In particular, it is preferable to satisfy the relationship of 0.15 ≦ E'c(-20°C) / E'out(-20°C) ≦ 1.30. Thereby, in a low-temperature environment, the durability of the transponder 20 can be effectively improved while ensuring the durability of the tire.

[0040] Here, if the value of E'c(-20°C) / E'out(-20°C) is less than the lower limit value, the rigidity of the coating layer 23 becomes low and the protective property deteriorates. Conversely, if the value of E'c(-20°C) / E'out(-20°C) is greater than the upper limit value, the rigidity of the coating layer 23 becomes high, the coating layer 23 becomes brittle, and the coating layer 23 is likely to break, so the transponder 20 is likely to be damaged.

[0041] As the composition of the coating layer 23, the coating layer 23 preferably comprises a rubber or an elastomer and 20 phr or more of a white filler. By configuring the coating layer 23 in this way, the relative permittivity of the coating layer 23 can be made relatively low compared to the case where carbon is contained, and the communication performance of the transponder 20 can be effectively improved. In this specification, "phr" means parts by weight per 100 parts by weight of the rubber component (elastomer).

[0042] The white filler constituting the coating layer 23 preferably contains 20 phr to 55 phr of calcium carbonate. Thereby, the relative permittivity of the coating layer 23 can be made relatively low, and the communication performance of the transponder 20 can be effectively improved. However, if the white filler contains an excessive amount of calcium carbonate, it becomes brittle and the strength as the coating layer 23 decreases, which is not preferable. In addition to calcium carbonate, the coating layer 23 can optionally contain 20 phr or less of silica (white filler) and 5 phr or less of carbon black. When a small amount of silica and carbon black are used in combination, the strength of the coating layer 23 can be ensured while reducing its relative permittivity.

[0043] Also, the relative permittivity of the coating layer 23 is preferably 7 or less, more preferably 2 to 5. By appropriately setting the relative permittivity of the coating layer 23 in this way, the radio wave transmissivity when the transponder 20 radiates radio waves can be ensured, and the communication performance of the transponder 20 can be effectively improved. Note that the relative permittivity of the rubber constituting the coating layer 23 is the relative permittivity at 860 MHz to 960 MHz at room temperature. Here, room temperature conforms to the standard state of JIS standards, which is 23 ± 2°C and 60% ± 5% RH. The relative permittivity of the rubber is measured by the capacitance method after being treated at 23°C and 60% RH for 24 hours. The above-mentioned range of 860 MHz to 960 MHz corresponds to the currently allocated frequencies of UHF band RFID. If the above-mentioned allocated frequencies are changed, the relative permittivity in the range of the allocated frequencies may be defined as described above.

[0044] The thickness t of the coating layer 23 is preferably 0.5 mm to 3.0 mm, more preferably 1.0 mm to 2.5 mm. Here, the thickness t of the coating layer 23 is the rubber thickness at the position including the transponder 20. For example, as shown in FIG. 4, it is the total rubber thickness of the thickness t1 and the thickness t2 on a straight line passing through the center of the transponder 20 and perpendicular to the tire surface (the outer tire surface in FIG. 4). By appropriately setting the thickness t of the coating layer 23 in this way, the communication performance of the transponder 20 can be effectively improved without causing unevenness on the tire surface. Here, if the thickness t of the coating layer 23 is less than 0.5 mm, the effect of improving the communication performance of the transponder 20 cannot be obtained. Conversely, if the thickness t of the coating layer 23 exceeds 3.0 mm, unevenness will occur on the tire surface, which is not preferable in terms of appearance. Note that the cross-sectional shape of the coating layer 23 is not particularly limited. For example, a triangle, a rectangle, a trapezoid, or a spindle shape can be adopted. The coating layer 23 in FIG. 4 has a substantially spindle-shaped cross-sectional shape.

[0045] In the pneumatic tire described above, it is preferable that the transponder 20 is disposed between a position P1, which is 15 mm radially outward from the upper end 5e (the radially outer end) of the bead core 5, and a position P2 where the maximum tire width is obtained, as the arrangement region in the tire radial direction. That is, it is preferable that the transponder 20 is disposed in the region S1 shown in FIG. 2. When the transponder 20 is disposed in the region S1, since the transponder 20 is located in a region where the stress amplitude during running is small, the durability of the transponder 20 can be effectively improved, and further, the durability of the tire is not deteriorated. Here, when the transponder 20 is disposed more radially inward than the position P1, the communication performance of the transponder 20 tends to deteriorate because it gets closer to metal members such as the bead core 5. On the other hand, when the transponder 20 is disposed more radially outward than the position P2, the transponder 20 is located in a region where the stress amplitude during running is large, and breakage of the transponder 20 itself or interfacial peeling around the transponder 20 is likely to occur, which is not preferable.

[0046] As shown in FIG. 3, there are a plurality of splice portions on the tire circumference where the ends of the tire constituent members overlap each other. FIG. 3 shows the position Q in the tire circumferential direction of each splice portion. It is preferable that the center of the transponder 20 is arranged at a distance of 10 mm or more from the splice portion of the tire constituent member in the tire circumferential direction. That is, it is good that the transponder 20 is arranged in the region S2 shown in FIG. 3. Specifically, it is good that the IC substrate 21 constituting the transponder 20 is separated from the position Q by 10 mm or more in the tire circumferential direction. Furthermore, it is more preferable that the entire transponder 20 including the antenna 22 is separated from the position Q by 10 mm or more in the tire circumferential direction, and most preferably, the entire transponder 20 covered with the covering rubber is separated from the position Q by 10 mm or more in the tire circumferential direction. Also, as the tire constituent member arranged separately from the transponder 20, it is preferable that it is the sidewall rubber layer 12 or the rim cushion rubber layer 13 arranged adjacent to the transponder 20, or the carcass layer 4. By arranging the transponder 20 separated from the splice portion of the tire constituent member in this way, the durability of the tire can be effectively improved.

[0047] In addition, in the embodiment of FIG. 3, an example in which the positions Q in the tire circumferential direction of the splice portions of each tire constituent member are arranged at equal intervals is shown, but it is not limited thereto. The position Q in the tire circumferential direction can be set at an arbitrary position, and in any case, the transponder 20 is arranged so as to be separated from the splice portion of each tire constituent member by 10 mm or more in the tire circumferential direction.

[0048] As shown in Fig. 4, the distance d between the center of the cross-section of the transponder 20 and the tire surface is preferably 1 mm or more. By separating the transponder 20 from the tire surface in this way, the durability of the tire can be effectively improved, and the puncture resistance of the tire can also be improved. In the embodiment of Fig. 4, the distance d is the distance between the center of the cross-section of the transponder 20 and the outer surface of the tire. However, when the transponder 20 is arranged close to the inner liner layer 9, the distance d is the distance between the center of the cross-section of the transponder 20 and the inner surface of the tire. In particular, the distance d between the center of the cross-section of the transponder 20 and the outer surface of the tire is preferably 2 mm or more.

[0049] In the above-described embodiment, an example is shown in which the terminal 4e of the turned-up portion 4B of the carcass layer 4 is arranged near the upper end 6e of the bead filler 6. However, the present invention is not limited to this, and the terminal 4e of the turned-up portion 4B of the carcass layer 4 can be arranged at an arbitrary height.

Example

[0050] In a pneumatic tire having a tire size of 265 / 40ZR20, a tread portion extending in the tire circumferential direction and having an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged on the inner side in the tire radial direction of these sidewall portions, a transponder is embedded outside the tire width direction from the carcass layer. The transponder is covered with a coating layer. Tires of Comparative Examples 1 to 4 and Examples 1 to 11 were manufactured in which the position of the transponder in the tire radial direction, the 50% modulus M50(0°C), M50(-20°C) / M50(0°C) of the coating layer at 0°C, the storage elastic modulus E'c(-20°C), E'c(-20°C) / E'out(-20°C) of the coating layer, the relative permittivity of the coating layer, and the thickness of the coating layer were set as shown in Table 1.

[0051] In Comparative Examples 1 to 4 and Examples 1 to 11, a columnar transponder was used, the circumferential distance of the tire from the center of the transponder to the splice portion of the tire component was set to 10 mm, and the distance from the center of the cross-section of the transponder to the outer surface of the tire was set to 2 mm or more.

[0052] In Table 1, the position of the transponder in the tire diameter direction corresponds to each of the positions A to E shown in FIG. 6.

[0053] For these test tires, tire evaluation (durability) and transponder evaluation (communication performance and durability) were carried out by the following test methods, and the results are shown together in Table 1.

[0054] Durability (tire and transponder): Each test tire was assembled on a wheel with a standard rim, and a running test was carried out on a drum tester under the conditions of a temperature of -20°C, an air pressure of 120 kPa, 102% of the maximum load, and a running speed of 81 km, and the running distance at the time of tire failure was measured. The evaluation results are shown as an index with Comparative Example 1 as 100. The larger this index value, the better the durability of the tire. Furthermore, for each test tire after running, the communication ability and the presence or absence of damage of the transponder were confirmed. The case where communication was possible and there was no damage was indicated as "◎ (excellent)", the case where communication was possible but there was damage was indicated as "○ (good)", and the case where communication was impossible was indicated in three levels of "× (impossible)".

[0055] Communication performance (transponder): For each test tire, communication work with the transponder was carried out using a reader / writer. Specifically, the longest communicable distance was measured with an output of 250 mW and a carrier frequency of 860 MHz to 960 MHz in the reader / writer. The evaluation results are shown as an index with Comparative Example 1 as 100. The larger this index value, the better the communication performance.

[0056]

Table 1

[0057] As can be seen from this Table 1, for the pneumatic tires of Examples 1 to 11, the durability of the tire and the durability of the transponder were improved in a well-balanced manner compared to Comparative Examples 1 to 4.

[0058] In Comparative Example 1, since the 50% modulus at 0°C, M50(0°C), of the coating layer was too low, the durability of the transponder was poor. In Comparative Example 2, since the value of M50(-20°C) / M50(0°C) of the coating layer was too low, the durability of the tire was poor. In Comparative Example 3, since the value of M50(-20°C) / M50(0°C) of the coating layer was too high, the durability of the transponder was poor. In Comparative Example 4, since the 50% modulus at 0°C, M50(0°C), of the coating layer was too high, the durability of the tire was poor.

Explanation of Symbols

[0059] 1 Tread portion 2 Sidewall portion 3 Bead portion 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 12 Sidewall rubber layer 13 Rim cushion rubber layer 20 Transponder 23 Coating layer CL Tire center line

Claims

1. In a pneumatic tire comprising a tread portion extending in the circumferential direction of the tire 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 transponder is embedded in the tire, the transponder is covered with a coating layer, the 50% modulus of deformation M50(0°C) of the coating layer at 0°C is in the range of 0.5 MPa to 2.0 MPa, and the 50% modulus of deformation M50(-20°C) of the coating layer at -20°C and the 50% modulus of deformation M50(0°C) of the coating layer at 0°C satisfy the relationship of 1.0 < M50(-20°C) / M50(0°C) ≤ 2.5, the storage elastic modulus E'c(-20°C) of the coating layer at -20°C is in the range of 3 MPa to 17 MPa, the transponder is embedded outside the tire width direction from the carcass layer, and the storage elastic modulus E'c(-20°C) of the coating layer and the storage elastic modulus E'out(-20°C) at -20°C of the rubber member having the largest storage elastic modulus at 20°C among the rubber members located outside the tire width direction from the transponder satisfy the relationship of 0.1 ≤ E'c(-20°C) / E'out(-20°C) ≤ 1.5, a pneumatic tire, characterized in that the center of the transponder is disposed at a distance of 10 mm or more in the circumferential direction of the tire from the splice portion of the tire constituent member.

2. The pneumatic tire according to claim 1, characterized in that the relative permittivity of the coating layer is 7 or less.

3. The pneumatic tire according to claim 1 or 2, characterized in that the coating layer is composed of rubber or an elastomer and a white filler of 20 phr or more.

4. The pneumatic tire according to claim 3, characterized in that the white filler contains calcium carbonate of 20 phr to 55 phr.

5. The pneumatic tire according to any one of claims 1 to 4, characterized in that the transponder is disposed between a position 15 mm radially outward from the upper end of the bead core of the bead portion and the maximum tire width position.

6. The pneumatic tire according to any one of claims 1 to 5, characterized in that the distance between the cross-sectional center of the transponder and the tire surface is 1 mm or more.

7. The pneumatic tire according to any one of claims 1 to 6, characterized in that the thickness of the coating layer is 0.5 mm to 3.0 mm.

8. The pneumatic tire according to any one of claims 1 to 7, wherein the transponder has an IC substrate for storing data and an antenna for transmitting and receiving data, and the antenna is spiral.

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