RFID module and pneumatic tire with embedded RFID module

Abstract

To provide an RFID module that can improve the durability of the RFID module while ensuring communication of the RFID module, and a pneumatic tire with the RFID module embedded.SOLUTION: An RFID module includes: an IC substrate 21 that stores data; an antenna 22 that transmits and receives data; and a coating layer 23 that covers the antenna 22. Tan δ(20°C) at 20°C of the coating layer 23 is equal to or less than 0.2. The coating layer 23 is softer than the IC substrate 21.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an RFID module and a pneumatic tire having the same embedded therein, and more specifically, to an RFID module and a pneumatic tire having the same embedded therein that make it possible to improve the durability of the RFID module while ensuring the communication performance of the RFID module. [Background technology]

[0002] RFID modules are embedded in pneumatic tires (see, for example, Patent Document 1). In order to extend the communication distance of the RFID module, it is preferable to provide an insulating layer that insulates the RFID module from the rubber members surrounding it. In such an insulating layer, if the tan δ of the insulating layer is higher than that of the surrounding rubber members, the buffer effect of the insulating layer cannot be obtained, resulting in a problem of deterioration in durability of the RFID module. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-137510 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an RFID module that makes it possible to improve the durability of the RFID module while ensuring the communication performance of the RFID module, and a pneumatic tire in which the RFID module is embedded. [Means for solving the problem]

[0005] In order to achieve the above object, the RFID module of the present invention includes an IC substrate for storing data, an antenna for transmitting and receiving the data, and a coating layer for coating the antenna, the coating layer having a tan δ(20° C.) of 0.2 or less at 20° C. and being softer than the IC substrate.The glass transition temperature of the coating layer is in the range of -70°C to -45°C. It is characterized by the above. In addition, the RFID module of the present invention comprises an IC substrate for storing data, an antenna for transmitting and receiving the data, and a coating layer for coating the antenna, wherein the coating layer has a tan δ(20°C) of 0.2 or less at 20°C, is softer than the IC substrate, and has a storage modulus E'c(20°C) of 20°C in the range of 2 MPa to 12 MPa.

[0006] The pneumatic tire of the present invention is characterized in that it comprises a tread portion extending circumferentially around the tire to form a ring, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged on the radially inward side of the sidewall portions, with a carcass layer mounted between the pair of bead portions, and the RFID module is embedded in the pneumatic tire. Effect of the Invention

[0007] In the RFID module of the present invention, the tan δ(20°C) of the coating layer at 20°C is 0.2 or less, so that a buffer effect can be obtained when the coating layer is deformed while ensuring the communication performance of the RFID module, thereby improving the durability of the RFID module. Furthermore, since the coating layer is softer than the IC substrate, the protective effect of the coating layer can be improved, which contributes to improving the durability of the RFID module.

[0008] In the RFID module of the present invention, the storage modulus E'c(20°C) of the covering layer at 20°C is preferably in the range of 2 MPa to 12 MPa, thereby improving the effect of protecting the RFID module by the covering layer and effectively improving the durability of the RFID module.

[0009] The relative dielectric constant of the covering layer is preferably equal to or less than 7. This makes it possible to effectively improve the communication performance of the RFID module.

[0010] The coating layer is preferably made of rubber or elastomer and 20 phr or more of calcium carbonate, which makes it possible to make the dielectric constant of the coating layer relatively low compared to when it contains carbon, and effectively improves the communication performance of the RFID module.

[0011] The calcium carbonate content of the coating layer is preferably 20 phr to 55 phr, which allows the relative dielectric constant of the coating layer to be relatively low, and effectively improves the communication performance of the RFID module.

[0012] The thickness of the covering layer is preferably 0.5 mm to 3.0 mm, which can effectively improve the communication performance of the RFID module while ensuring the protective effect of the covering layer.

[0013] The coating layer has a dielectric loss tangent of 0.1 or less and a surface resistivity of 10 12 Ω·m or more, and the volume resistivity is 10 12 It is preferable that the dielectric loss tangent is Ω·m or more. By setting the dielectric loss tangent in the above range, it is possible to prevent attenuation of the radio wave intensity when the radio wave passes through the RFID module, and by setting the electrical resistance in the above range, it is possible to effectively improve the communication performance of the RFID module.

[0014] The glass transition temperature of the coating layer is preferably in the range of −70° C. to −45° C. This allows the RFID module to be used in high or low temperature environments without impairing its durability.

[0015] In the pneumatic tire of the present invention, it is preferable that the tan δ(20° C.) at 20° C. of the covering layer is lower than the tan δ(20° C.) at 20° C. of the rubber member disposed adjacent to the covering layer, thereby effectively improving the durability of the RFID module.

[0016] The RFID module is disposed on the outer side of the carcass layer in the tire width direction, and it is preferable that the storage modulus at 20°C E'c(20°C) of the covering layer and the storage modulus at 20°C E'out(20°C) of the rubber member with the largest storage modulus at 20°C among the rubber members disposed on the outer side of the RFID module in the tire width direction satisfy the relationship 0.1≦E'c(20°C) / E'out(20°C)≦1.5. This makes it possible to effectively improve the durability of the RFID module.

[0017] It is preferable that the center of the RFID module is disposed 10 mm or more away from the splice portion of the tire constituent members in the tire circumferential direction, which can effectively improve the durability of the tire.

[0018] The RFID module is preferably disposed between the position 15 mm radially outward from the upper end of the bead core of the bead portion and the maximum tire width position, whereby the RFID module is disposed in an area where the stress amplitude during running is small, effectively improving the durability of the RFID module without reducing the durability of the tire.

[0019] It is preferable that the distance between the cross-sectional center of the RFID module and the tire surface is 1 mm or more, which can effectively improve the durability of the tire and improve the external damage resistance of the tire.

[0020] The antenna is preferably spiral, which allows it to follow the deformation of the tire while it is moving, improving the durability of the RFID module.

[0021] In the present invention, the storage modulus E' and the loss tangent tanδ are measured in a tensile deformation mode using a viscoelasticity spectrometer under the conditions of a specified temperature, a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of ±2% in accordance with JIS-K6394. The surface resistivity [Ω·m] and the volume resistivity [Ω·m] of the coating layer are measured in accordance with JIS-K6271. [Brief description of the drawings]

[0022] [Figure 1] 1A and 1B show an example of an RFID module according to an embodiment of the present invention, where 1A is a perspective view and 1B is a cross-sectional view. [Diagram 2] 1 is a meridian half cross-sectional view showing a pneumatic tire in which an RFID module according to an embodiment of the present invention is embedded. [Diagram 3] 3 is a meridian cross-sectional view that illustrates the pneumatic tire of FIG. 2. [Figure 4] 3 is an equatorial cross-sectional view that illustrates the pneumatic tire of FIG. 2. [Diagram 5] 3 is an enlarged cross-sectional view showing the RFID module embedded in the pneumatic tire of FIG. 2. [Figure 6] 1A and 1B show a modified example of an RFID module according to an embodiment of the present invention, where 1A is a perspective view and 1B is a cross-sectional view. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which: Figures 1(a) and 1(b) show an RFID module according to an embodiment of the present invention.

[0024] As shown in Figs. 1(a) and 1(b), the RFID module 10 of this embodiment is composed of a transponder 20 and a covering layer 23 that covers the transponder 20. For example, an RFID (Radio Frequency Identification) tag can be used as the transponder 20. The transponder 20 has an IC substrate 21 that stores data, and an antenna 22 that transmits and receives data in a non-contact manner. By using such a transponder 20, data can be written or read at appropriate times and efficiently managed. RFID is an automatic recognition technology that is composed of a reader / writer having an antenna and a controller, and an ID tag having an IC substrate and an antenna, and is capable of wirelessly communicating data.

[0025] In Fig. 1(a), the antenna 22 of the transponder 20 protrudes from both ends of the IC substrate 21 and has a spiral shape. Communication performance can be ensured by appropriately changing the length of the antenna 22. The overall shape of the transponder 20 is not particularly limited, and in addition to the columnar shape shown in Figs. 1(a) and (b), a plate-like shape shown in Figs. 6(a) and (b) may also be used.

[0026] The covering layer 23 is a viscoelastic body and has elastic properties at room temperature. The covering layer 23 is made of rubber or elastomer. In the present invention, tan δ(20°C) at 20°C is used as an index to indicate elastic properties, and the tan δ(20°C) of the covering layer 23 is 0.2 or less. Preferably, the tan δ(20°C) of the covering layer 23 is in the range of 0.05 to 0.15. In addition, the covering layer 23 is softer than the IC substrate 21 of the transponder 20. That is, the covering layer 23 is configured to have a lower hardness than the IC substrate 21. For example, the JIS hardness of the covering layer 23 at 20°C is preferably in the range of 40 to 60. The JIS hardness (20°C) is a durometer hardness measured at a temperature of 20°C using a type A durometer in accordance with JIS-K6253.

[0027] In the RFID module described above, since the tan δ(20° C.) of the covering layer 23 at 20° C. is 0.2 or less, a buffer effect can be obtained when the covering layer 23 is deformed while ensuring the communication performance of the RFID module 10, thereby improving the durability of the RFID module 10. Furthermore, since the covering layer 23 is softer than the IC substrate 21, the protective effect of the covering layer 23 can be improved, which contributes to improving the durability of the RFID module 10.

[0028] On the other hand, if the coating layer has viscous properties at room temperature, for example, if the tan δ(20°C) of the coating layer at 20°C is greater than 0.2, the cushioning effect of the coating layer cannot be fully obtained, and the durability of the RFID module will be deteriorated.

[0029] In the RFID module, the covering layer 23 has a dielectric loss tangent of 0.1 or less and a surface resistivity of 10 12 Ω·m or more, and the volume resistivity is 10 12It is preferable that the dielectric loss tangent is Ω·m or more. By setting the dielectric loss tangent in the above range, it is possible to prevent attenuation of the radio wave intensity when the radio wave passes through the RFID module 10, and by setting the electrical resistance in each of the above ranges, it is possible to effectively improve the communication performance of the RFID module 10.

[0030] The storage modulus E'c(20°C) of coating layer 23 at 20°C is preferably in the range of 2 MPa to 12 MPa. By setting the physical properties of coating layer 23 in this manner, the effect of coating layer 23 in protecting RFID module 10 is improved, and the durability of RFID module 10 can be effectively improved.

[0031] The glass transition temperature of the coating layer 23 is preferably in the range of −70° C. to −45° C., and more preferably in the range of −60° C. to −45° C. This allows the RFID module 10 to be used in high or low temperature environments without impairing its durability. If the glass transition temperature of the coating layer 23 is lower than the lower limit, the heat resistance of the coating layer 23 deteriorates and the protective effect of the coating layer 23 in a high temperature environment cannot be sufficiently obtained. Conversely, if the glass transition temperature of the coating layer 23 exceeds the upper limit, the durability in a low temperature environment deteriorates and the coating layer 23 becomes more likely to crack.

[0032] The coating layer 23 is preferably composed of rubber or elastomer and 20 phr or more of calcium carbonate. By configuring the coating layer 23 in this way, the relative dielectric constant of the coating layer 23 can be made relatively low compared to when carbon is contained, and the communication properties of the RFID module 10 can be effectively improved. The greater the content of calcium carbonate, the lower the relative dielectric constant can be. For example, when the coating layer 23 contains calcium carbonate that is more than 25 phr and not more than 30 phr, the relative dielectric constant of the coating layer 23 can be set to 4 or more and less than 6. When the coating layer 23 contains calcium carbonate that is more than 30 phr and not more than 40 phr, the relative dielectric constant of the coating layer 23 can be set to 2 or more and less than 4. In this specification, "phr" means parts by weight per 100 parts by weight of the rubber component (elastomer).

[0033] The calcium carbonate contained in the coating layer 23 is preferably 20 phr to 55 phr. This allows the relative dielectric constant of the coating layer 23 to be relatively low, and the communication properties of the RFID module 10 to be effectively improved. However, if the coating layer 23 contains an excessive amount of calcium carbonate, it becomes brittle and the strength of the coating layer 23 decreases, which is not preferable. In addition to calcium carbonate, the coating layer 23 may optionally contain 20 phr or less of silica (white filler) or 5 phr or less of carbon black. When a small amount of silica or carbon black is used in combination, the relative dielectric constant of the coating layer 23 can be reduced while maintaining the strength of the coating layer 23.

[0034] The dielectric constant of the covering layer 23 is preferably 7 or less, more preferably 2 to 5. By appropriately setting the dielectric constant of the covering layer 23 in this way, radio wave permeability when the transponder 20 radiates radio waves can be ensured, and the communication performance of the transponder 20 can be effectively improved. The dielectric constant of the rubber constituting the covering layer 23 is 860 MHz to 960 MHz at room temperature. Here, the room temperature conforms to the standard conditions of the JIS standard, which are 23±2°C and 60%±5% RH. The dielectric constant 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 frequency of UHF RFID, but if the above-mentioned allocated frequency is changed, the dielectric constant of the range of the allocated frequency may be specified as described above.

[0035] The thickness t of the covering layer 23 is preferably 0.5 mm to 3.0 mm, and more preferably 1.0 mm to 2.5 mm. Here, the thickness t of the covering layer 23 is the rubber thickness at a position including the transponder 20, and is, for example, the rubber thickness obtained by adding up the thickness t1 and the thickness t2 on a straight line passing through the center of the transponder 20 as shown in FIG. 1(b). By appropriately setting the thickness t of the covering layer 23 in this manner, the communication performance of the RFID module 10 can be effectively improved while ensuring the protective effect of the covering layer 23. Here, if the thickness t of the covering layer 23 is thinner than 0.5 mm, the insulation performance of the covering layer 23 decreases, and the effect of improving the communication performance of the RFID module 10 cannot be sufficiently obtained. Conversely, if the thickness t of the covering layer 23 exceeds 3.0 mm, the RFID module 10 may be damaged when embedded in a tire. The cross-sectional shape of the covering layer 23 is not particularly limited, and may be, for example, a triangular, rectangular, trapezoidal, or spindle shape. The coating layer 23 in FIG. 1(b) has a rectangular cross-sectional shape.

[0036] 2 to 5 show a pneumatic tire according to an embodiment of the present invention. As shown in Fig. 2, the pneumatic tire of this embodiment includes a tread portion 1 extending in the tire circumferential direction to form 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 inner side of the sidewall portions 2 in the tire radial direction.

[0037] At least one carcass layer 4 (one layer in FIG. 2) is disposed between a pair of bead portions 3, and is made up of a plurality of carcass cords arranged in the radial direction. 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 and having a triangular cross section is disposed on the outer periphery of the bead core 5.

[0038] Meanwhile, on the tire outer circumferential side of the carcass layer 4 in the tread portion 1, multiple belt layers 7 (two layers in FIG. 2) are embedded. The belt layer 7 includes multiple reinforcing cords inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to cross each other between 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 10° to 40°, for example. As the reinforcing cords of the belt layer 7, steel cords are preferably used.

[0039] At least one belt cover layer 8 (two layers in FIG. 2) is disposed on the tire outer periphery side of the belt layer 7, 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. In FIG. 2, 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 portions 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.

[0040] In the above pneumatic tire, both ends 4e of the carcass layer 4 are folded back around each bead core 5 from the inside to the outside of the tire, and are disposed so as to encase the bead cores 5 and the bead fillers 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 rolled-up portion 4B which is a portion rolled up around the bead cores 5 in each bead portion 3 and extends toward each sidewall portion 2.

[0041] In addition, an inner liner layer 9 is disposed on the inner surface of the tire along the carcass layer 4. A cap tread rubber layer 11 is disposed on the tread portion 1, a sidewall rubber layer 12 is disposed on the sidewall portion 2, and a rim cushion rubber layer 13 is disposed on the bead portion 3.

[0042] An RFID module 10 is embedded in the pneumatic tire configured as described above. In Fig. 2, the RFID module 10 is disposed at a position on the outer side in the tire width direction than the carcass layer 4. A transponder 20 constituting the RFID module 10 extends along the tire circumferential direction. This transponder 20 may be disposed so as to be inclined in the range of -10° to 10° with respect to the tire circumferential direction.

[0043] In the pneumatic tire described above, since the RFID module 10 is embedded, the durability of the RFID module 10 can be improved while ensuring the communication performance of the RFID module 10. Furthermore, since the RFID module 10 is embedded on the outer side of the carcass layer 4 in the tire width direction, there is no tire component that blocks radio waves during communication of the RFID module 10, and the communication performance of the RFID module 10 can be well ensured. When the RFID module 10 is embedded on the outer side of the carcass layer 4 in the tire width direction, the RFID module 10 can be disposed 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, the RFID module 10 can be disposed 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.

[0044] In the above pneumatic tire, as shown in Fig. 1(a), it is preferable that the antenna 22 is spiral-shaped. By using the antenna 22 having such a shape, it is possible to follow the deformation of the tire during running, and the durability of the RFID module 10 can be improved.

[0045] Moreover, it is preferable that the tan δ(20°C) at 20°C of the covering layer 23 is lower than the tan δ(20°C) at 20°C of the rubber members (the coating rubber of the carcass layer 4 and the rim cushion rubber layer 13 in FIG. 2) disposed adjacent to the covering layer 23. By setting the tan δ(20°C) at 20°C of the covering layer 23 in this manner, the durability of the RFID module 10 can be effectively improved.

[0046] Furthermore, among the rubber members located outside the RFID module 10 in the tire width direction (sidewall rubber layer 12 and rim cushion rubber layer 13 in Figure 2), the rubber member (hereinafter sometimes referred to as the outer member) with the largest storage modulus at 20°C E'out(20°C) corresponds to the rim cushion rubber layer 13, and it is preferable that the storage modulus at 20°C E'c(20°C) of the covering layer 23 and the storage modulus at 20°C E'out(20°C) of the rubber member with the largest storage modulus at 20°C among the rubber members located outside the RFID module 10 in the tire width direction satisfy the relationship 0.1≦E'c(20°C) / E'out(20°C)≦1.5, and it is more preferable that the relationship 0.15≦E'c(20°C) / E'out(20°C)≦1.30. Since the difference in rigidity between the covering layer 23 and the rubber member located outside the RFID module 10 is unlikely to become excessively large, the rigidity of the covering layer 23 relative to the rubber member can be kept at an appropriate level, thereby improving the durability of the RFID module 10.

[0047] Here, when the value of E'c(20°C) / E'out(20°C) is smaller than the lower limit, the rigidity of the coating layer 23 becomes lower than that of the external member, and the protective effect on the RFID module 10 decreases. Conversely, when the value of E'c(20°C) / E'out(20°C) is greater than the upper limit, the rigidity of the coating layer 23 becomes higher than that of the external member, making the coating layer 23 brittle and more susceptible to breakage, which may lead to damage to the RFID module 10.

[0048] It is preferable that the storage modulus E'c(20°C) of coating layer 23 at 20°C and the storage modulus E'c(60°C) of coating layer 23 at 60°C satisfy the relationship 1.0≦E'c(20°C) / E'c(60°C)≦1.5. Setting the physical properties of coating layer 23 in this manner reduces the temperature dependency of coating layer 23 (coating layer 23 is less likely to generate heat), so that coating layer 23 does not soften even if the tire temperature rises during high-speed driving, and the durability of RFID module 10 can be effectively improved.

[0049] It is preferable that the storage modulus E'c(60°C) at 60°C of the covering layer 23 and the storage modulus E'a(60°C) at 60°C of the rubber member adjacent to the covering layer 23 on the outer side in the tire width direction (rim cushion rubber layer 13 in FIG. 2) satisfy the relationship 0.2≦E'c(60°C) / E'a(60°C)≦1.2. By setting the physical properties of the covering layer 23 and the rubber member adjacent to the covering layer 23 in this way, the physical properties of the two become closer, thereby obtaining the effect of dispersing stress during driving and effectively improving the durability of the RFID module 10.

[0050] In the above pneumatic tire, the RFID module 10 is preferably disposed between a position P1 15 mm outward in the tire radial direction from the upper end 5e (the outer end in the tire radial direction) of the bead core 5 and a position P2 at which the tire is at its maximum width, as a tire radial arrangement region. That is, the RFID module 10 is preferably disposed in the region S1 shown in FIG. 3. When the RFID module 10 is disposed in the region S1, the RFID module 10 is located in a region where the stress amplitude during running is small, so that the durability of the RFID module 10 can be effectively improved, and further, the durability of the tire is not reduced. Here, when the RFID module 10 is disposed on the inner side in the tire radial direction than the position P1, the RFID module 10 is close to metal members such as the bead core 5, and therefore the communication performance of the RFID module 10 tends to deteriorate. On the other hand, when the RFID module 10 is disposed on the outer side in the tire radial direction than the position P2, the RFID module 10 is located in a region where the stress amplitude during running is large, and the transponder 20 itself is easily damaged, and the interface peeling is likely to occur around the RFID module 10, which is not preferable.

[0051] As shown in FIG. 4, there are a plurality of splice parts formed by overlapping the ends of tire constituent members on the tire circumference. FIG. 4 shows the tire circumferential position Q of each splice part. It is preferable that the center of the RFID module 10 is arranged 10 mm or more away from the splice part of the tire constituent member in the tire circumferential direction. That is, the RFID module 10 is arranged in the region S2 shown in FIG. 4. Specifically, it is preferable that the IC board 21 constituting the RFID module 10 is 10 mm or more away from the position Q in the tire circumferential direction. Furthermore, it is more preferable that the entire RFID module 10 including the antenna 22 is 10 mm or more away from the position Q in the tire circumferential direction, and it is most preferable that the entire RFID module 10 in a state covered with the covering rubber is 10 mm or more away from the position Q in the tire circumferential direction. In addition, it is preferable that the tire constituent member arranged at a distance from the RFID module 10 is the sidewall rubber layer 12 or the rim cushion rubber layer 13 arranged adjacent to the RFID module 10, or the carcass layer 4. By arranging the RFID module 10 away from the splice portion of the tire constituent members in this manner, the durability of the tire can be effectively improved.

[0052] 4, an example is shown in which the tire circumferential positions Q of the splices of each tire constituent member are arranged at equal intervals, but the present invention is not limited to this. The tire circumferential positions Q can be set at any positions, and in any case, the RFID module 10 is arranged so as to be spaced 10 mm or more away from the splices of each tire constituent member in the tire circumferential direction.

[0053] As shown in Fig. 5, the distance d between the center of the cross section of the RFID module 10 and the tire surface is preferably 1 mm or more. By separating the RFID module 10 from the tire surface in this manner, the durability of the tire can be effectively improved and the tire resistance to external damage can be improved. In the embodiment of Fig. 5, the distance d is the distance between the center of the cross section of the RFID module 10 and the tire outer surface, but when the RFID module 10 is disposed in a position close to the inner liner layer 9, the distance d is the distance between the center of the cross section of the RFID module 10 and the tire inner surface.

[0054] In the above-described embodiment, an example has been shown in which the terminal 4e of the turned-up portion 4B of the carcass layer 4 is disposed near the upper end 6e of the bead filler 6, but this is not limited thereto, and the terminal 4e of the turned-up portion 4B of the carcass layer 4 can be disposed at any height. For example, the terminal 4e of the turned-up portion 4B of the carcass layer 4 may be disposed on the side of the bead core 5. In such a roll-up structure, the transponder 20 can be disposed between the bead filler 6 and the sidewall rubber layer 12 or the rim cushion rubber layer 13. In this case, the rubber member adjacent to the outer side of the covering layer 23 in the tire width direction becomes the sidewall rubber layer 12 or the rim cushion rubber layer 13. EXAMPLES

[0055] RFID modules were produced for Comparative Examples 1 and 2 and Examples 1 to 8, each having an IC substrate for storing data, an antenna for transmitting and receiving data, and a coating layer for coating the antenna, with the tan δ (20°C) of the coating layer at 20°C (20°C), the hardness of the coating layer, the storage modulus E'c (20°C) of the coating layer, the dielectric constant of the coating layer, the calcium carbonate content of the coating layer, and the thickness of the coating layer set as shown in Table 1.

[0056] In Table 1, when the hardness of the coating layer is "soft", it means that the coating layer is softer than the IC substrate, and when the hardness of the coating layer is "hard", it means that the coating layer is harder than the IC substrate.

[0057] The durability and communication performance of these RFID modules were evaluated using the test methods described below, and the results are shown in Table 1.

[0058] Durability: For each RFID module, a constant strain fatigue test was conducted in which the module was subjected to repeated deformation 3 million times at a temperature of 30°C to 40°C, an extension speed of 400±20 rpm, and a constant strain of 80%, and then the RFID module was checked for visual failures. The evaluation results were shown on a four-level scale: "◎ (excellent)" if there was no visual failure, "○ (good)" if there was a visual failure but the failure was not caused by the transponder covered by the coating layer, "△ (passable)" if there was a visual failure caused by the transponder covered by the coating layer, and "× (unacceptable)" if there was a visual failure that made communication with the RFID module impossible.

[0059] Connectivity: A communication task was carried out for each RFID module using a reader / writer. Specifically, the longest communication distance was measured with the reader / writer at an output of 250 mW and a carrier frequency of 860 MHz to 960 MHz. The evaluation results are shown as an index with Comparative Example 1 being 100. A higher index value means better communication performance.

[0060] [Table 1]

[0061] As can be seen from Table 1, the RFID modules of Examples 1 to 8 were improved in durability and communication performance compared to Comparative Example 1.

[0062] On the other hand, in Comparative Example 2, the coating layer was configured to be harder than the IC substrate, and therefore durability was deteriorated. [Explanation of symbols]

[0063] 1 Tread section 2 Sidewall 3 Bead section 4 Carcass layer 10 RFID Module 20 Transponder 21 IC board 22 Antenna 23 Covering layer CL Tire centerline

Claims

1. An RFID module comprising an IC substrate for storing data, an antenna for transmitting and receiving the data, and a coating layer for coating the antenna, wherein the coating layer has a tan δ(20°C) of 0.2 or less at 20°C, the coating layer is softer than the IC substrate, and the glass transition temperature of the coating layer is in the range of -70°C to -45°C.

2. 2. The RFID module according to claim 1, wherein the cover layer has a storage modulus E'c (20° C.) at 20° C. in the range of 2 MPa to 12 MPa.

3. 3. The RFID module according to claim 1, wherein the covering layer has a relative dielectric constant of 7 or less.

4. 4. The RFID module according to claim 1, wherein the coating layer is made of rubber or elastomer and 20 phr or more of calcium carbonate.

5. 5. The RFID module according to claim 4, wherein the coating layer contains 20 phr to 55 phr of calcium carbonate.

6. The RFID module according to any one of claims 1 to 5, wherein the coating layer has a thickness of 0.5 mm to 3.0 mm.

7. The coating layer has a dielectric loss tangent of 0.1 or less and a surface resistivity of 10 12 Ω·m or more, and the volume resistivity is 10 12 7. The RFID module according to claim 1, wherein the resistance is Ω·m or more.

8. An RFID module comprising an IC substrate for storing data, an antenna for transmitting and receiving said data, and a coating layer for coating said antenna, wherein said coating layer has a tan δ(20°C) of 0.2 or less at 20°C, said coating layer is softer than said IC substrate, and said coating layer has a storage modulus E'c(20°C) at 20°C in the range of 2 MPa to 12 MPa.

9. A pneumatic tire comprising a tread portion extending circumferentially in a tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on either side of the tread portion, and a pair of bead portions arranged on the radially inward side of the sidewall portions, with a carcass layer mounted between the pair of bead portions, wherein the RFID module according to any one of claims 1 to 8 is embedded in the pneumatic tire.

10. The pneumatic tire according to claim 9, characterized in that the tan δ (20°C) at 20°C of the coating layer is lower than the tan δ (20°C) at 20°C of a rubber member disposed adjacent to the coating layer.

11. The pneumatic tire according to claim 9 or 10, characterized in that the RFID module is positioned outside the carcass layer in the tire width direction, and the storage modulus E'c (20°C) of the covering layer at 20°C and the storage modulus E'out (20°C) of the rubber member with the largest storage modulus at 20°C among the rubber members located outside the RFID module in the tire width direction satisfy the relationship 0.1≦E'c (20°C) / E'out (20°C)≦1.

5.

12. The pneumatic tire according to any one of claims 9 to 11, characterized in that the center of the RFID module is arranged 10 mm or more away from the splice portion of the tire constituent members in the tire circumferential direction.

13. The pneumatic tire according to any one of claims 9 to 12, characterized in that the RFID module is arranged between a position 15 mm radially outward from an upper end of a bead core of the bead portion and a maximum width position of the tire.

14. The pneumatic tire according to any one of claims 9 to 13, characterized in that the distance between the center of a cross section of the RFID module and the tire surface is 1 mm or more.

15. The pneumatic tire according to any one of claims 9 to 14, characterized in that the antenna is spiral.

16. A pneumatic tire comprising a tread portion extending circumferentially in a ring shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed radially inward of the sidewall portions, a carcass layer mounted between the pair of bead portions, and an RFID module embedded therein, the RFID module includes an IC substrate for storing data, an antenna for transmitting and receiving the data, and a coating layer for coating the antenna, the coating layer having a tan δ(20° C.) of 0.2 or less at 20° C., and the coating layer being softer than the IC substrate; A pneumatic tire, characterized in that the center of the RFID module is arranged 10 mm or more away from the splice portion of the tire constituent members in the tire circumferential direction.

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