Pneumatic tire

Abstract

To provide a pneumatic tire which enables improvement of resistance to breakage of a transponder while maintaining good communication performance of the transponder.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 sealant of the sealant layer 20 is formed of a silicone composition. Relative permittivity of the sealant layer 20 is 7 or smaller. A transponder 40 is arranged so as to contact with the sealant layer 20.SELECTED DRAWING: Figure 2

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 specifically, to a pneumatic tire that makes it possible to improve the damage resistance of a transponder while maintaining good communication performance of the transponder. [Background technology]

[0002] It has been proposed to provide a sealant layer on the radially inner side of the inner liner layer in the tread of a pneumatic tire. In such a pneumatic tire, when a foreign object such as a nail penetrates the tread, the sealant flows into the through hole, thereby suppressing the decrease in air pressure and enabling the tire to continue running.

[0003] Conventionally, the sealant constituting the sealant layer is generally a rubber composition mainly composed of butyl-based rubber (see, for example, Patent Documents 1 to 3). Examples of butyl-based rubber include butyl rubber (IIR) and halogenated butyl rubber such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR).

[0004] Meanwhile, it has been proposed to embed an RFID tag (transponder) in a pneumatic tire (for example, see Patent Document 4). The transponder functions as a medium for storing identification information of the tire and is used for quality control, inventory management, driving history, etc. Such transponders are generally embedded in the sidewall of the pneumatic tire.

[0005] However, when the transponder is disposed in the sidewall portion, there is a problem that the transponder is easily broken when the pneumatic tire hits a curb, etc. Also, when the transponder is embedded in the tread portion instead of the sidewall portion, there is a problem that the communication performance of the transponder is deteriorated due to interference with the belt layer embedded in the tread portion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6583456 [Patent Document 2] Patent No. 6620851 [Patent Document 3] Patent No. 7319533 [Patent Document 4] Special Publication No. 2021-514891 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a pneumatic tire that makes it possible to improve the damage resistance of a transponder while maintaining good communication performance of the transponder. [Means for solving the problem]

[0008] In order to achieve the above object, a pneumatic tire of the present invention includes a tread portion extending in a 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 radially inner side of the sidewall portions, a carcass layer is fitted 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, The tire is characterized in that a sealant layer is disposed on the inner surface of the tire in the tread portion, the sealant of the sealant layer is composed of a silicone-based composition, the sealant layer has a relative dielectric constant of 7 or less, and a transponder is disposed so as to be in contact with the sealant layer. Effect of the Invention

[0009] In the present invention, in a pneumatic tire having a sealant layer disposed on the tire inner surface in the tread portion, the sealant of the sealant layer is made of a silicone-based composition, and the transponder is disposed so as to be in contact with the sealant layer, so that the transponder is less likely to be broken even if the pneumatic tire hits a curb, etc., and the damage resistance of the transponder can be improved. In addition, since the relative dielectric constant of the sealant layer is 7 or less and the transponder is in contact with such a sealant layer, the communication performance of the transponder can be maintained well.

[0010] In the present invention, the storage modulus E'(30°C) of the sealant layer at 30°C is preferably in the range of 5 kPa to 20 kPa. By optimizing the storage modulus E'(30°C) of the sealant layer at 30°C in this manner, it is possible to increase the impact resistance based on the sealant layer and improve the breakage resistance of the transponder, and also to suppress the flow of the sealant when the tire is running, thereby suppressing deformation of the sealant layer.

[0011] In the present invention, the ratio E'(-30°C) / E'(30°C) of the storage modulus E'(30°C) at 30°C to the storage modulus E'(-30°C) at -30°C is preferably smaller than the ratio E's(-30°C) / E's(30°C) of the storage modulus E's(30°C) at 30°C to the storage modulus E's(-30°C) at -30°C of the sidewall rubber layer disposed in the sidewall portion. By making the hardness change at low temperatures smaller in the sealant layer than in the sidewall rubber layer in this way, the breakage resistance of the transponder at low temperatures can be improved.

[0012] In the present invention, the tan δ of the sealant layer at 100° C. is preferably 0.5 or less. By lowering the tan δ of the sealant layer at 100° C. in this manner, the flow of the sealant during high-speed driving can be suppressed, thereby suppressing the movement of the transponder.

[0013] In the present invention, the silicone composition is preferably a two-component curing silicone. Two-component curing silicone has a low viscosity immediately after mixing the two components and can be applied even at low temperatures, which increases the productivity of pneumatic tires equipped with a sealant layer.

[0014] In the present invention, it is preferable that the transponder is disposed on the outer side in the tire width direction than a position that is 90% of the width of the belt layer located on the outermost side in the tire radial direction. By disposing the transponder on the outer side in the tire width direction than a position that is 90% of the width of the belt layer located on the outermost side in the tire radial direction, it is possible to minimize the influence of metal members such as the belt layer and improve communication performance.

[0015] In the present invention, the storage modulus E', E's and loss tangent tanδ are measured in accordance with JIS-K6394 using a viscoelasticity spectrometer in a tensile deformation mode under the conditions of a specified temperature, a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of ±2%. [Brief description of the drawings]

[0016] [Figure 1] 1 is a meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing a main part of the pneumatic tire of FIG. [Diagram 3] 1(a) and 1(b) are perspective views showing an example of a transponder used in the present invention. [Figure 4] 1(a) to 1(d) are meridian cross-sectional views showing the arrangement of transponders according to the present invention. [Diagram 5] 2 is a cross-sectional view showing a method for manufacturing the pneumatic tire of FIG. 1. [Figure 6] 2 is a plan view showing a sealant layer formed on the inner surface of the tire in the tread portion of the pneumatic tire of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The configuration of the present invention will be described in detail below with reference to the accompanying drawings. Figures 1 and 2 show a pneumatic tire according to an embodiment of the present invention, Figures 3(a) and 3(b) each show an example of a transponder used in the present invention, and Figures 4(a) to 4(d) each show an arrangement of the transponder in the present invention. It is something that is.

[0018] As shown in FIG. 1, the pneumatic tire of this embodiment includes a tread portion 1 extending circumferentially around the tire to form an annular shape, a pair of sidewall portions 2, 2 arranged on either side of the tread portion 1, and a pair of bead portions 3, 3 arranged radially inward of the sidewall portions 2.

[0019] A carcass layer 4 is fitted between a 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 inside to the outside of the tire around a bead core 5 arranged in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross section is arranged on the outer periphery of the bead core 5.

[0020] On the other hand, multiple belt layers 7 (7A, 7B) are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include multiple belt cords inclined with respect to the tire circumferential direction, and are arranged so that the belt cords cross each other between the layers. In the belt layers 7, the inclination angle of the belt cords with respect to the tire circumferential direction is set in the range of 10° to 40°, for example. As the belt cords of the belt layers 7, steel cords are preferably used.

[0021] At least one belt cover layer 8 is arranged on the outer periphery of the belt layer 7, in order to improve high-speed durability, and is made of reinforcing cords arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction. This belt cover layer 8 is preferably of a jointless structure in which a strip material made of at least one reinforcing cord aligned and rubber-coated is continuously wound at an angle of substantially 0° with respect to the tire circumferential direction. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or polyethylene terephthalate (PET) is preferably used.

[0022] The above-mentioned tire internal structure shows a typical example of a pneumatic tire, but is not limited thereto. An inner liner layer 9 (air permeation prevention layer) is arranged along the carcass layer 4 on the inside of the carcass layer 4. Various grooves including a plurality of main grooves 11 extending in the tire circumferential direction are formed in the tread portion 1. Furthermore, a tread rubber layer R1 is arranged on the outside of the belt cover layer 8 in the tread portion 1, a sidewall rubber layer R2 is arranged on the outside of the carcass layer 4 in the sidewall portion 2, and a rim cushion rubber layer R3 is arranged on the outside of the carcass layer 4 in the bead portion 3.

[0023] In the above pneumatic tire, as shown in FIG. 1 and FIG. 2, the sealant layer 20 is disposed on the tire inner surface 10 in the tread portion 1 so as to be continuous in the tire circumferential direction. 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 from the tire equator CL toward either side in the tire width direction. 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. This prevents the sealant layer 20 from adversely affecting the tire balance. The sealant of the sealant layer 20 is composed of a silicone-based composition. The silicone-based composition includes a synthetic polymer compound having a main skeleton formed by a siloxane bond. The relative dielectric constant of the sealant layer 20 composed of a sealant of the silicone-based composition is 7 or less.

[0024] In the pneumatic tire, the transponder 40 is arranged so as to be in contact with the sealant layer 20 while being oriented so as to extend along the tire circumferential direction. For example, an RFID (Radio Frequency Identification) tag can be used as the transponder 40. As shown in Figs. 3(a) and (b), the transponder 40 has an IC board 41 for storing data and an antenna 42 for transmitting and receiving data in a non-contact manner. By using such a transponder 40, information about the tire can be written or read at appropriate times, and the tire can be efficiently managed. Note that 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 board and an antenna, and is capable of wirelessly communicating data.

[0025] The overall shape of the transponder 40 is not particularly limited, and for example, a columnar or plate-shaped one can be used as shown in Figs. 3(a) and (b). In particular, the columnar transponder 40 shown in Fig. 3(a) is preferable because it can follow the deformation of the tire in each direction. In this case, the antenna 42 of the transponder 40 protrudes from both ends of the IC board 41 and has a spiral shape. This allows the transponder 40 to follow the deformation of the tire during running, and the durability of the transponder 40 can be improved. In addition, communication can be ensured by appropriately changing the length of the antenna 42. The transponder 40 may be covered with a coating rubber, a primer, or the like.

[0026] The transponder 40 may be arranged in the manners shown in Figs. 4(a) to 4(d). For example, in Fig. 4(a), the transponder 40 is embedded inside the sealant layer 20. In Fig. 4(b), the transponder 40 is arranged on the inner side of the sealant layer 20 in the tire radial direction (upper side in the figure). In this case, the transponder 40 is attached to the sealant layer 20 based on the adhesiveness of the sealant layer 20. In Fig. 4(c), the transponder 40 is arranged between the sealant layer 20 and the inner liner layer 9. In Fig. 4(d), the transponder 40 is arranged on the inner side of the sealant layer 20 in the tire radial direction (upper side in the figure), and the transponder 40 is sandwiched between the sealant layer 20 and a cover layer 25 made of the same material as the sealant layer 20.

[0027] According to the above-mentioned pneumatic tire, the sealant layer 20 is disposed on the tire inner surface 10 in the tread portion 1, the sealant of the sealant layer 20 is composed of a silicone-based composition, and the transponder 40 is disposed so as to be in contact with the sealant layer 20, so that the transponder is unlikely to be broken even if the pneumatic tire hits a curb or the like. In other words, if the transponder 40 is disposed in the sidewall portion 2 as in the conventional case, the transponder 40 may be pinched between the rim and the curb or the like and broken when the pneumatic tire hits a curb or the like, but since the transponder 40 is disposed in the tread portion 1, such damage caused by the curb or the like can be avoided. Moreover, the shock to the transponder 40 is mitigated by the cushioning effect of the sealant layer 20. As a result, the breakage resistance of the transponder 40 can be improved. In addition, the sealant layer 20 made of a silicone-based composition sealant has a relative dielectric constant of 7 or less, and the transponder 40 is in contact with such a sealant layer 20, so that radio wave transparency is ensured when the transponder 40 radiates radio waves, and the communication properties of the transponder 40 can be maintained well.

[0028] Here, if the relative dielectric constant of the sealant layer 20 is larger than 7, the effect of improving the communication performance of the transponder 40 decreases. In particular, it is desirable that the relative dielectric constant of the sealant layer 20 is in the range of 2 to 5. For example, the relative dielectric constant of silicone rubber is in the range of 3.0 to 3.5. The relative dielectric constant of the sealant layer 20 is 860 MHz to 960 MHz at room temperature. The room temperature conforms to the standard conditions of the JIS standard, which are 23±2°C and 60%±5% RH. The sealant of the sealant layer 20 is treated at 23°C and 60% RH for 24 hours, and then the relative dielectric constant is measured by the capacitance method. 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 relative dielectric constant of the range of the allocated frequency may be specified as described above.

[0029] In the above pneumatic tire, the storage modulus E'(30°C) of the sealant layer 20 at 30°C is preferably in the range of 5 kPa to 20 kPa. By optimizing the storage modulus E'(30°C) of the sealant layer 20 at 30°C in this manner, it is possible to increase the impact resistance based on the sealant layer 20 and improve the breakage resistance of the transponder 40, and also to suppress the flow of the sealant during tire running, thereby suppressing deformation of the sealant layer 20. Here, if the storage modulus E'(30°C) of the sealant layer 20 at 30°C is smaller than 5 kPa, the sealant will flow during tire running, making it easier for deformation of the sealant layer 20 to occur, and conversely, if it is larger than 20 kPa, the impact resistance based on the sealant layer 20 will decrease, reducing the effect of improving the breakage resistance of the transponder 40.

[0030] In the above pneumatic tire, it is preferable that the ratio E'(-30°C) / E'(30°C) of the storage modulus E'(30°C) at 30°C to the storage modulus E'(-30°C) at -30°C of the sealant layer 20 is smaller than the ratio E's(-30°C) / E's(30°C) of the storage modulus E's(30°C) at 30°C to the storage modulus E's(-30°C) at -30°C of the sidewall rubber layer R2 disposed in the sidewall portion 2. That is, although the storage modulus E' of the sealant layer 20 and the storage modulus E's of the sidewall rubber layer R2 both tend to increase as the temperature decreases, by satisfying the above-mentioned relationship, the change in hardness at low temperatures of the sealant layer 20 is made smaller than that of the sidewall rubber layer R2, thereby improving the breakage resistance of the transponder 40 at low temperatures. Here, if the ratio E'(-30°C) / E'(30°C) is greater than the ratio E's(-30°C) / E's(30°C), the effect of improving the resistance of the transponder 40 to damage at low temperatures decreases.

[0031] In the above pneumatic tire, it is preferable that the tan δ of the sealant layer 20 at 100° C. is 0.5 or less. By lowering the tan δ of the sealant layer 20 at 100° C. in this manner, it is possible to suppress the flow of the sealant during high-speed driving, thereby suppressing the movement of the transponder 40. Here, if the tan δ of the sealant layer 20 at 100° C. is greater than 0.5, the effect of suppressing the movement of the transponder 40 due to the flow of the sealant is reduced.

[0032] In the above pneumatic tire, the transponder 40 is preferably disposed on the outside in the tire width direction of a position that is 90% of the width Wb of the belt layer 7B located on the outermost side in the tire radial direction (in the case of a tire having two belt layers 7A, 7B, the second belt layer 7B counting from the inner side in the tire radial direction). By disposing the transponder 40 on the outside in the tire width direction of a position that is 90% of the width Wb of the belt layer 7B located on the outermost side in the tire radial direction, the influence of metal members such as the belt layer 7 can be minimized to enhance communication performance. Here, if the transponder 40 is disposed on the inside in the tire width direction of the above position, the effect of improving communication performance is reduced.

[0033] The above-mentioned pneumatic tire can be manufactured by the following method. First, a pneumatic tire is manufactured as described above, which includes a tread portion 1, a pair of sidewall portions 2, and a pair of bead portions 3, a carcass layer 4 mounted between the pair of bead portions 3, 3, and a belt layer 7 embedded on the outer circumferential side of the carcass layer 4 in the tread portion 1. Next, a sealant made of a silicone-based composition is applied to the tire inner surface 10 in the tread portion 1 to form a sealant layer 20. After that, a transponder 40 is disposed so as to be in contact with the sealant layer 20, for example, as shown in Figs. 4(a) to (d).

[0034] FIG. 5 shows a specific manufacturing method of the pneumatic tire of FIG. 1, and FIG. 6 shows a sealant layer formed on the inner surface of the tire in the tread portion. In FIG. 5, a sealant extrusion device 31 mixes sealants supplied from pumps 32 and 33, and continuously discharges the mixed sealant from a nozzle 34 as a strip 21. This sealant extrusion device 31 is configured so that the position of the nozzle 34 can be freely changed. Therefore, by moving the nozzle 34 in the tire axial direction while rotating the tire from a state in which the nozzle 34 is close to the inner surface 10 of the tire, the strip 21 of sealant can be arranged in a spiral shape on the inner surface 10 of the tire while inclining with respect to the tire circumferential direction Tc (see FIG. 6). The spirally arranged sealant strip 21 has its circumferential portions in close contact with each other. The sealant strip 21 arranged in a spiral shape is integrated to form the sealant layer 20.

[0035] In the above-mentioned pneumatic tire, a sealant layer 20 having a structure in which a sealant strip 21 is arranged spirally along the tire circumferential direction is formed on the tire inner surface 10 in the tread portion 1, and the sealant is composed of a silicone-based composition, so that the circumferential portions of the sealant strip 21 become easily compatible with 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, thereby improving the sealing property of the sealant layer 20. In addition, since the integrity of the circumferential portions of the sealant strip 21 is good, the sealant layer 20 is less likely to flow toward the center in the tire width direction due to the centrifugal force generated during tire rotation, which also contributes to improving the sealing property. Furthermore, when a silicone-based composition is used as the sealant of the sealant layer 20, there is an advantage that it has excellent weather resistance and has low temperature dependency of physical properties.

[0036] Since the silicone-based composition has good fluidity even at low temperatures, it is preferable to set the temperature of the sealant applied to the tire inner surface 10 to be lower than 70°C. This reduces the effect of heat on the tire and prevents deterioration of tire performance. If the temperature is 70°C or higher, the effect of heat on the tire increases, which causes deterioration of tire performance. In particular, it is preferable that the temperature of the sealant applied to the tire inner surface 10 is 35°C or lower. In addition, from the viewpoint of the fluidity of the silicone-based composition, the lower limit of the temperature of the sealant applied to the tire inner surface 10 is 20°C.

[0037] As the silicone-based composition constituting the sealant of the sealant layer 20, one-component curing silicone or two-component curing silicone can be used, but it is particularly preferable to use two-component curing silicone. One-component curing silicone is, for example, moisture-curing silicone. Two-component curing silicone is composed of a first liquid and a second liquid, and a curing reaction starts by mixing these first liquid and second liquid, and the stability of the sealant layer 20 is ensured after curing. In the above-mentioned device, the first liquid and the second liquid of the two-component curing silicone are supplied from pumps 32 and 33, respectively. Since the viscosity of the two-component curing silicone is low immediately after mixing the two liquids, it can be applied even at low temperatures. Therefore, the productivity of pneumatic tires equipped with a sealant layer is increased. In particular, it is preferable that the two-component curing silicone has a period of 5 days or more until it is completely cured.

[0038] The two-component curing 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, organic polymers 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, and enoxysilane. Examples of the filler include iron oxide, titanium dioxide, carbon black, and talc. Examples of the condensation catalyst include titanate and zirconate. These condensation curable silyl-terminated polymers, silane crosslinking agents, condensation catalysts, and fillers are stored in a state in which they are separated into a first liquid and a second liquid in a combination that does not cause a curing reaction to proceed, and are mixed when used.

[0039] In the above pneumatic tire, the glass transition temperature of the sealant of the sealant layer 20 is preferably in the range of -120°C to -40°C. By using a sealant with a low glass transition temperature, good puncture sealing properties can be ensured in low temperature environments. If the glass transition temperature of the sealant is higher than -40°C, the puncture sealing properties in low temperature environments are reduced.

[0040] In the above pneumatic tire, as shown in FIG. 2, the thickness S of the sealant layer 20 is preferably in the range of 2.0 mm to 5.0 mm. This ensures puncture sealing performance while suppressing deterioration of rolling resistance due to an increase in tire weight and suppressing uneven distribution of the sealant layer 20 due to the flow of the sealant. If the thickness S of the sealant layer 20 is smaller than 2.0 mm, the puncture sealing performance decreases, and conversely, if it is larger than 5.0 mm, the rolling resistance may deteriorate due to an increase in tire weight and uneven distribution of the sealant layer 20 may occur due to the flow of the sealant. The thickness S of the sealant layer 20 is the average thickness of the entire tire. The average thickness of the sealant layer 20 can be calculated from the measured values ​​at a total of 40 points by, for example, photographing the tire meridian cross section at eight points on the circumference of the tire using a CT scan, and measuring the thickness of the sealant layer 20 at five points in each photographed image, 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 position.

[0041] In the above pneumatic tire, when the belt layers 7 (7A, 7B) including belt cords inclined with respect to the tire circumferential direction are embedded in the tread portion 1 as shown in Fig. 2, it is preferable that the distance (shortest distance) L from the belt layer 7A located at the innermost side in the tire radial direction to the sealant layer 20 is 10 mm or less at all points of the belt layer 7A. This makes it easier for the sealant to flow into the belt layer 7A when a foreign object such as a nail penetrates the tread portion 1, thereby ensuring good puncture sealing properties. If there is a part where the distance L from the belt layer 7A to the sealant layer 20 is greater than 10 mm, there is a risk that the puncture sealing properties at that part will be insufficient.

[0042] In the above pneumatic tire, it is preferable that the ratio of the thickness S of the sealant layer 20 to the distance L from the belt layer 7A located at the innermost side in the tire radial direction to the sealant layer 20 satisfies the relationship S / L≧0.3. By making the thickness S of the sealant layer 20 sufficiently large relative 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 is reduced. EXAMPLES

[0043] In a pneumatic tire having a tire size of 255 / 45R19 and including a tread portion, a pair of sidewall portions, and a pair of bead portions, with a carcass layer mounted between the pair of bead portions and a belt layer embedded on the outer circumferential side of the carcass layer in the tread portion, a sealant layer was disposed on the inner surface of the tire in the tread portion, while tires of Comparative Examples 1-2 and Examples 1-9 were manufactured with different types of transponders, different presence or absence of a covering rubber covering the transponder, and different positions of the transponder.

[0044] In Comparative Examples 1-2 and Examples 1-9, the sealant of the sealant layer was a silicone-based composition (SST-2650 manufactured by Dow), the relative dielectric constant of the sealant layer was 7, the storage modulus E'(30°C) of the sealant layer at 30°C was 20 kPa, the storage modulus E'(-30°C) of the sealant layer at -30°C was 30 kPa, the ratio E'(-30°C) / E'(30°C) was 1.5, the tan δ of the sealant layer at 100°C was 0.5, and the ratio E's(-30°C) / E's(30°C) of the storage modulus E's(30°C) at 30°C to the storage modulus E's(-30°C) of the sidewall rubber layer was 5.5.

[0045] The type of transponder, the presence or absence of a covering rubber that covers the transponder, and the position of the transponder (tire thickness direction, tire width direction) are as shown in Table 1. Regarding the position of the transponder in the tire thickness direction, "carcass / side" means that the transponder is disposed between the carcass layer and the sidewall rubber layer, and "carcass / liner" means that the transponder is disposed between the carcass layer and the inner liner layer. Regarding the position of the transponder in the tire width direction, "side" means that the transponder is disposed in the sidewall portion, "center" means that the transponder is disposed at the tire equator, and "shoulder" means that the transponder is disposed on the outer side in the tire width direction than the position that is 90% of the width of the belt layer that is located at the outermost side in the tire radial direction.

[0046] For these test tires, the initial communication property and the communication property after the impact test were evaluated by the following test method. The results are shown in Table 1.

[0047] Connectivity: For each test tire, a reader / writer was used to communicate with the transponder. 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 were as follows: when the communication distance was 1.0 m or more, it was indicated with "◎", when the communication distance was 0.7 m or more, it was indicated with "○", when the communication distance was 0.1 m or more, it was indicated with "△", and when the communication distance was less than 0.1 m, it was indicated with "×". Such evaluations were performed initially (when the tire was new) and after the impact test. In the impact test, each test tire was mounted on a vehicle, and the tire was hit against a curb at an air pressure of 150 kPa and a speed of 20 km / h, and the part of each test tire where the transponder was located was hit against a curb, and the impact was repeated 20 times.

[0048] [Table 1]

[0049] As can be seen from Table 1, in the tires of Examples 1 to 9, the transponders were not damaged by the impact test, and the transponders had good initial and post-crash communication properties. In contrast, in the tire of Comparative Example 1, the transponder was disposed in the sidewall portion, so the initial communication properties were good, but the communication properties after the impact test were significantly deteriorated. In the tire of Comparative Example 2, the transponder was disposed between the carcass layer and the inner liner layer at the tire equator, so the initial communication properties were somewhat poor, and the communication properties after the impact test were significantly deteriorated.

[0050] The present disclosure includes the following inventions [1] to [6]. Invention [1] is a pneumatic tire comprising a tread portion extending in a 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 radially inner side of the sidewall portions, a carcass layer is fitted 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, The pneumatic tire is characterized in that a sealant layer is disposed on the tire inner surface in the tread portion, the sealant of the sealant layer is composed of a silicone-based composition, the sealant layer has a relative dielectric constant of 7 or less, and a transponder is disposed so as to be in contact with the sealant layer. Invention [2] is the pneumatic tire according to invention [1], characterized in that the storage modulus E'(30°C) of the sealant layer at 30°C is in the range of 5 kPa to 20 kPa. Invention [3] is the pneumatic tire according to invention [1] or [2], characterized in that a ratio E'(-30°C) / E'(30°C) of a storage modulus E'(30°C) at 30°C to a storage modulus E'(-30°C) at -30°C is smaller than a ratio E's(-30°C) / E's(30°C) of a storage modulus E's(30°C) at 30°C to a storage modulus E's(-30°C) at -30°C of a sidewall rubber layer disposed in the sidewall portion. The invention [4] is the pneumatic tire according to any one of the inventions [1] to [3], characterized in that the sealant layer has a tan δ at 100° C. of 0.5 or less. The invention [5] is the pneumatic tire according to any one of the inventions [1] to [4], characterized in that the silicone-based composition is a two-component curing silicone. Invention [6] is a pneumatic tire according to any one of inventions [1] to [5], characterized in that the transponder is arranged outward in the tire width direction from a position that is 90% of the width of the belt layer located at the outermost side in the tire radial direction. [Explanation of symbols]

[0051] 1 Tread section 2 Sidewall 3 Bead section 4 Carcass layer 5 Bead Core 6 Bead Filler 7 Belt layer 8 Belt cover layer 9 Inner liner layer 10 Tire inner surface 20 Sealant Layer 21 Sealant Strip 25 Cover Layer 40 Transponder

Claims

1. A pneumatic tire comprising a tread portion extending in a 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 tire radially inward side of the sidewall portions, a carcass layer being fitted between the pair of bead portions, and a belt layer being embedded on the outer peripheral side of the carcass layer in the tread portion, a sealant layer is disposed on an inner surface of the tire in the tread portion, the sealant of the sealant layer is composed of a silicone-based composition, the sealant layer has a relative dielectric constant of 7 or less, and a transponder is disposed so as to be in contact with the sealant layer.

2. 2. The pneumatic tire according to claim 1, wherein the sealant layer has a storage modulus E'(30° C.) at 30° C. in the range of 5 kPa to 20 kPa.

3. The pneumatic tire according to claim 1 or 2, characterized in that a ratio E'(-30°C) / E'(30°C) of the storage modulus E'(30°C) at 30°C to the storage modulus E'(-30°C) at -30°C is smaller than a ratio E's(-30°C) / E's(30°C) of the storage modulus E's(30°C) at 30°C to the storage modulus E's(-30°C) at -30°C of the sidewall rubber layer disposed in the sidewall portion.

4. 3. The pneumatic tire according to claim 1, wherein the sealant layer has a tan δ of 0.5 or less at 100°C.

5. 3. The pneumatic tire according to claim 1, wherein the silicone-based composition is a two-component curing silicone.

6. The pneumatic tire according to claim 1 or 2, characterized in that the transponder is arranged on the outer side in the tire width direction than a position that corresponds to 90% of a width of a belt layer that is located on the outermost side in the tire radial direction.

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