Manufacturing method of pneumatic tire

Abstract

To provide a pneumatic tire manufacturing method that can suppress tire vulcanization failure.SOLUTION: A coating layer 23 for coating a transponder 20 has, in a thickness direction thereof, a front surface layer 23x positioned on a front side of the transponder 20 and a rear surface layer 23y positioned on a rear side of the transponder 20. A step 24 is formed so that end positions of the front surface layer 23x and the rear surface layer 23y are not coincident with each other at at least one end of both ends 23a, 23b of the coating layer 23 in a width direction. The transponder 20 coated with the coating layer 23 having the step 24 is embedded in an unvulcanized tire, and the unvulcanized tire is vulcanized.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a pneumatic tire in which a transponder covered with a covering layer is embedded, and more particularly, to a method for manufacturing a pneumatic tire that makes it possible to suppress vulcanization failures of the tire. [Background technology]

[0002] It has been proposed to embed an RFID tag (transponder) in a pneumatic tire (for example, see Patent Document 1). In addition, when a transponder is covered with a covering layer and embedded in a tire, a gap is generated between the covering layer and the rubber member around it, which causes a problem of vulcanization failure. [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 a method for manufacturing a pneumatic tire that makes it possible to suppress vulcanization defects in the tire. [Means for solving the problem]

[0005] In order to achieve the above object, the method for manufacturing a pneumatic tire of the present invention is a method for manufacturing a pneumatic tire in which a transponder is embedded in a tire, the method comprising the steps of: forming a covering layer for covering the transponder, the covering layer having a surface layer located on the surface side of the transponder in the thickness direction and a back layer located on the back side of the transponder; forming a step at at least one end of both ends in the width direction of the covering layer such that the end positions of the surface layer and the back layer do not coincide with each other; and embedding the transponder covered with the covering layer having the step in an unvulcanized tire. When performing the above-mentioned, the transponder is arranged so that the longitudinal direction of the transponder is within a range of ±10° with respect to the circumferential direction of the forming drum,The present invention is characterized in that an unvulcanized tire is vulcanized. The method for manufacturing a pneumatic tire of the present invention is a method for manufacturing a pneumatic tire in which a transponder is embedded in the tire, characterized in that a covering layer covering the transponder has a surface layer located on the surface side of the transponder in the thickness direction and a back layer located on the back side of the transponder, a step is formed at at least one end of both ends in the width direction of the covering layer so that the end positions of the surface layer and the back layer do not coincide with each other, the transponder covered with the covering layer having the step is embedded in an unvulcanized tire, the unvulcanized tire is vulcanized, the relative dielectric constant of the covering layer is lower than the relative dielectric constant of a rubber member arranged adjacent to the covering layer, and a total thickness Gac of the covering layer and a maximum thickness Gar of the transponder satisfy the relationship of 1.1≦Gac / Gar≦3.0. The method for manufacturing a pneumatic tire of the present invention is a method for manufacturing a pneumatic tire in which a transponder is embedded in a tire, characterized in that a covering layer covering the transponder has a surface layer located on the surface side of the transponder in its thickness direction and a back layer located on the back side of the transponder, a step is formed at at least one end of both ends in the width direction of the covering layer so that the end positions of the surface layer and the back layer do not coincide with each other, the transponder covered with the covering layer having the step is embedded in an unvulcanized tire, the unvulcanized tire is vulcanized, and the Mooney viscosity of the covering layer is lower than the Mooney viscosity of a rubber member arranged adjacent to the covering layer. The method for producing a pneumatic tire of the present invention is a method for producing a pneumatic tire in which a transponder is embedded in a tire, the method comprising the steps of: a covering layer covering the transponder having a surface layer located on the surface side of the transponder in the thickness direction and a back layer located on the back side of the transponder; forming a step at at least one end of both ends in the width direction of the covering layer such that the end positions of the surface layer and the back layer do not coincide with each other; embedding the transponder covered with the covering layer having the step in an unvulcanized tire; vulcanizing the unvulcanized tire; and detecting a minimum value M in a vulcanization curve obtained from torque detection by a rheometer in the covering layer. Lc The minimum value M in the vulcanization curve obtained by detecting torque by a rheometer in the rubber member disposed adjacent to the coating layer Lt is characterized in that it is lower than Effect of the Invention

[0006] In the present invention, the covering layer that covers the transponder has a surface layer located on the surface side of the transponder in the thickness direction and a back layer located on the back side of the transponder, and a step is formed at at least one end of both ends in the width direction of the covering layer so that the end positions of the surface layer and the back layer do not coincide with each other, and by embedding the transponder covered with the covering layer having this step in an unvulcanized tire and vulcanizing the unvulcanized tire, it is possible to reduce the gap generated by the step between the covering layer and the rubber member arranged adjacent to the covering layer, thereby suppressing vulcanization failures of the tire around the transponder.

[0007] In the method for manufacturing a pneumatic tire of the present invention, when sandwiching the transponder between the front layer and the back layer, it is preferable to form a step by shifting the end positions of the front layer and the back layer at at least one end of both ends in the width direction of the covering layer, thereby effectively suppressing vulcanization failure of the tire.

[0008] It is preferable to form the steps at both ends in the width direction of the covering layer, which can effectively suppress vulcanization defects of the tire.

[0009] The width of the step is preferably 1.5 mm to 5.0 mm, which can effectively suppress vulcanization failure of the tire and improve the durability of the tire.

[0010] At least one of the surface layer and the back layer preferably has a thickness of 0.5 mm to 2.5 mm, which can effectively prevent vulcanization failure of the tire.

[0011] It is preferable that the dielectric constant of the covering layer is lower than that of the rubber member disposed adjacent to the covering layer, and the total thickness Gac of the covering layer and the maximum thickness Gar of the transponder satisfy the relationship 1.1≦Gac / Gar≦3.0. This allows the transponder to be sufficiently isolated from the adjacent rubber member and enveloped in the covering layer with a low dielectric constant, improving the communication performance of the transponder. In addition, by specifying the upper limit of the total thickness Gac of the covering layer relative to the maximum thickness Gar of the transponder, the durability of the tire can be sufficiently ensured.

[0012] The covering layer is made of elastomer or rubber, and preferably has a relative dielectric constant of not more than 7. This ensures radio wave permeability of the transponder, and effectively improves the communication performance of the transponder.

[0013] The Mooney viscosity of the coating layer is preferably lower than that of the rubber member disposed adjacent to the coating layer, which improves the rubber flow of the coating layer during vulcanization and makes vulcanization failure less likely to occur even if a gap occurs between the coating layer and the adjacent rubber member.

[0014] The minimum M in the cure curve obtained from torque detection by a rheometer in the coating layer Lc is the minimum value M in the vulcanization curve obtained by detecting torque with a rheometer in the rubber member located adjacent to the coating layer. Lt This improves the flow of rubber in the coating layer during vulcanization, making it difficult for voids to form between the coating layer and the adjacent rubber member, thereby making it possible to effectively suppress vulcanization defects in the tire.

[0015] It is preferable to arrange the transponder so that the longitudinal direction of the transponder is within a range of ±10° with respect to the circumferential direction of the building drum, which can effectively improve the durability of the tire.

[0016] It is preferable that the center of the transponder 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.

[0017] The transponder is preferably disposed between a position 15 mm outward in the tire radial direction from the upper end of the bead core of the bead portion and a position 5 mm inward in the tire radial direction from the end of the belt layer. This makes it difficult for metallic interference to occur, and ensures the communication performance of the transponder. [Brief description of the drawings]

[0018] [Figure 1] 1 is a meridian half cross-sectional view showing an example of a pneumatic tire to which a manufacturing method for a pneumatic tire according to the present invention can be applied. [Diagram 2] FIG. 2 is a cross-sectional view showing a main part of the pneumatic tire of FIG. [Diagram 3] 2(a) and 2(b) are perspective views showing a transponder that can be embedded in the pneumatic tire of FIG. 1. [Figure 4] 1A and 1B show a transponder covered with a covering layer, where 1A is a perspective view and 1B is a cross-sectional view. [Diagram 5] 3(a) and 3(b) are perspective views showing a forming step of forming a covering layer step in the manufacturing method of the pneumatic tire according to the present invention. FIG. [Figure 6] 3(a) and 3(b) are explanatory views showing a molding step in the manufacturing method of a pneumatic tire according to the present invention. [Figure 7] FIG. 2 is a cross-sectional view showing a transponder embedded in a pneumatic tire while being covered with a covering layer. [Figure 8] 2 is a meridian cross-sectional view illustrating the pneumatic tire of FIG. 1. FIG. [Figure 9] 2 is an equatorial cross-sectional view that illustrates the pneumatic tire of FIG. 1. [Figure 10]10 is a cross-sectional view showing a main portion of a modified example of a pneumatic tire to which the pneumatic tire manufacturing method according to the present invention can be applied. FIG. [Figure 11] 14(a) to 14(h) show modified shapes of the coating layer, with 14(a) to 14(e) being cross-sectional views and 14(f) to 14(h) being plan views. [Figure 12] FIG. 2 is an explanatory diagram showing radial positions of transponders in a test tire. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings, in which: Figures 1 and 2 show a pneumatic tire to which a manufacturing method for a pneumatic tire according to the present invention is applied.

[0020] 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 arranged on either side of the tread portion 1, and a pair of bead portions 3 arranged radially inward of the sidewall portions 2.

[0021] At least one carcass layer 4 (one layer in FIG. 1) 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.

[0022] 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. 1) 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.

[0023] At least one belt cover layer 8 (two layers in FIG. 1) 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. 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 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.

[0024] 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.

[0025] 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.

[0026] In the pneumatic tire, a transponder 20 is embedded between the carcass layer 4 and the inner liner layer 9. As shown in Fig. 2, the transponder 20 is covered with a covering layer 23. The covering layer 23 covers the entire transponder 20 so as to sandwich both the front and back sides of the transponder 20.

[0027] For example, an RFID (Radio Frequency Identification) tag can be used as the transponder 20. As shown in Figs. 3(a) and (b), the transponder 20 has an IC board 21 for storing data and an antenna 22 for contactlessly transmitting and receiving data. By using such a transponder 20, tire-related information can be written or read at appropriate times, enabling efficient tire management. 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.

[0028] The overall shape of the transponder 20 is not particularly limited, and may be, for example, a columnar or plate-shaped one as shown in Fig. 3(a) and (b). In particular, the columnar transponder 20 shown in Fig. 3(a) is preferable because it can follow the deformation of the tire in each direction. In this case, the antenna 22 of the transponder 20 protrudes from both ends of the IC substrate 21 and has a spiral shape. This allows the transponder 20 to follow the deformation of the tire during running, and the durability of the transponder 20 can be improved. In addition, communication performance can be ensured by appropriately changing the length of the antenna 22.

[0029] 1, an example is shown in which the end 4e of the turned-up portion 4B of the carcass layer 4 is disposed in the middle of the sidewall portion 2, but the present invention is not limited to this, and the end 4e of the turned-up portion 4B of the carcass layer 4 can be disposed at any height. For example, the end 4e of the turned-up portion 4B of the carcass layer 4 may be disposed to the side of the bead core 5.

[0030] Next, a method for manufacturing a pneumatic tire of the present invention will be described. When manufacturing a pneumatic tire as described above, an inner liner layer 9 is placed on a molding drum, and a transponder 20 covered with a covering layer 23 and tire components consisting of a carcass layer 4, a bead core 5, a bead filler 6, a belt layer 7, and a belt cover layer 8 are laminated thereon, and a cap tread rubber layer 11, a sidewall rubber layer 12, and a rim cushion rubber layer 13 are bonded together to form an unvulcanized tire, which is then vulcanized to manufacture the tire.

[0031] In such a manufacturing process, a forming step is performed in advance to form steps 24 in the covering layer 23 that covers both the front and back sides of the transponder 20. In this forming step, as shown in Figs. 4(a) and (b), the steps 24 are formed so that the positions of at least one of the ends 23a, 23b in the width direction of the covering layer 23 do not coincide on both sides of the covering layer 23. In Figs. 4(a) and (b), the steps 24 are formed only on the end 23b in the width direction of the covering layer 23. Here, the covering layer 23 has a front layer 23x located on the front side of the transponder 20 (upper side in Fig. 4(b)) and a back layer 23y located on the back side of the transponder 20 (lower side in Fig. 4(b)) in the thickness direction. The front layer 23x and the back layer 23y may each be composed of a plurality of layers. The front layer 23x and the back layer 23y are divided in the thickness direction of the covering layer 23 with the center line of the transponder 20 as a boundary. The end positions of the surface layer 23x and the back layer 23y do not coincide with each other, in other words, the width Wx of the surface layer 23x and the width Wy of the back layer 23y are different. Furthermore, in addition to the end of the width direction of the covering layer 23, the step 24 may be formed so that the end positions of at least one of both ends 23c, 23d of the covering layer 23 in the length direction do not coincide on both sides of the covering layer 23. That is, the step 24 is a portion where the ends 23a to 23d of the covering layer 23 in the width direction and / or length direction are shifted on both sides of the covering layer 23. The length direction of the covering layer 23 is the extension direction of the transponder 20, and the width direction of the covering layer 23 is a direction perpendicular to the extension direction of the transponder 20.

[0032] In the process of forming the steps 24 in the covering layer 23, for example, when forming the covering layer 23 having the cross-sectional shape shown in FIG. 4(a) and (b), as shown in FIG. 5(a), two covering layers 23 having different widths and rectangular cross-sectional shapes are used, and the covering layers 23 are laminated so that the widthwise ends of one side of the covering layers 23 coincide with each other to cover the entire transponder 20. In this way, the step 24 can be formed at the widthwise end of the other side of the laminated covering layers 23. In this case, the number of layers constituting the covering layer 23 can be set arbitrarily. Also, as shown in FIG. 5(b), one covering layer 23 having a rectangular cross-sectional shape may be used, and the covering layer 23 may be folded to cover the entire transponder 20. In this way, the step 24 can be formed at the widthwise end of one side of the covering layer 23. As another method (not shown), two coating layers 23 having the same width and a rectangular cross-sectional shape may be used, and these coating layers 23 may be stacked to cover the entire transponder 20, and then the step 24 may be formed by removing at least one end of the stacked coating layers 23 in the width direction.

[0033] In the above-mentioned method for manufacturing a pneumatic tire, the covering layer 23 covering the transponder 20 has a surface layer 23x located on the surface side of the transponder 20 in the thickness direction and a back layer 23y located on the back side of the transponder 20, and steps 24 are formed at at least one end of both ends 23a, 23b in the width direction of the covering layer 23 so that the end positions of the surface layer 23x and the back layer 23y do not coincide with each other, and the transponder 20 covered with the covering layer 23 having the steps 24 is embedded in an unvulcanized tire and the unvulcanized tire is vulcanized, thereby making it possible to reduce the gap generated by the steps 24 between the covering layer 23 and a rubber member (e.g., the inner liner layer 9) arranged adjacent to the covering layer 23. This makes it possible to suppress vulcanization failures of the tire around the transponder 20.

[0034] In contrast, when a transponder coated with a coating layer without steps is used, steps are formed locally on the circumference of the unvulcanized tire, and gaps are generated around the transponder between the coating layer and the rubber member disposed adjacent to the coating layer, making the tire more susceptible to vulcanization failure. In this case, if the transponder is disposed on the outer side of the carcass layer in the tire width direction, air is trapped and cracks are more likely to occur around the transponder. On the other hand, if the transponder is disposed on the inner side of the carcass layer in the tire width direction, it becomes convex toward the inner side in the tire radial direction, so the release agent is trapped and cracks are more likely to occur around the transponder.

[0035] In the above-mentioned method for manufacturing a pneumatic tire, when the transponder 20 is sandwiched between the surface layer 23x and the back layer 23y, the step 24 may be formed by shifting the end positions of the surface layer 23x and the back layer 23y at at least one end of the widthwise ends 23a, 23b of the covering layer 23. For example, the entire transponder 20 can be covered by disposing the strip-shaped surface layer 23x and the back layer 23y extruded from each extruder on both the front and back sides of the transponder 20. At that time, the surface layer 23x and the back layer 23y extruded from each extruder have different widths, and the end positions of the surface layer 23x and the back layer 23y are shifted in the width direction. This allows the step 24 to be formed at at least one end of the widthwise ends 23a, 23b of the covering layer 23. By covering the transponder 20 in this manner, vulcanization failure of the tire can be effectively suppressed.

[0036] It is particularly preferable to form the steps 24 at both widthwise ends of the covering layer 23. By providing the steps 24 in the covering layer 23 in this manner, the gap between the covering layer 23 and the rubber member disposed adjacent to the covering layer 23 can be further reduced, making it possible to effectively suppress vulcanization failures in the tire.

[0037] In addition, when the transponder 20 covered with the covering layer 23 having the steps 24 is placed on the forming drum D, as shown in Figs. 6(a) and (b), it is preferable to place the transponder 20 so that the longitudinal direction of the transponder 20 is within a range of ±10° with respect to the circumferential direction of the forming drum D. That is, the inclination angle θ shown in the figure is preferably in a range of -10° to 10°. This inclination angle θ is the angle between the circumferential direction of the forming drum D and the center line L of the entire transponder 20. In particular, when the widths of both sides of the covering layer 23 are different, it is preferable to place the wider one of the two sides of the covering layer 23 (for example, the back layer 23y shown in Fig. 4(b)) on the carcass layer 4 side. By placing the transponder 20 with respect to the forming drum D in this way, the durability of the tire can be effectively improved.

[0038] In the above-mentioned method for manufacturing a pneumatic tire, the Mooney viscosity of the covering layer 23 is preferably lower than that of the rubber member disposed adjacent to the covering layer 23. Examples of such adjacent rubber members include the carcass layer 4, the bead filler 6, the inner liner layer 9, the sidewall rubber layer 12, and the rim cushion rubber layer 13. The ratio of the Mooney viscosity [ML(1+4)100°C] of the covering layer 23 to the Mooney viscosity [ML(1+4)100°C] of the adjacent rubber member is preferably 0.3 to 0.9, more preferably 0.5 to 0.8, and most preferably 0.5 to 0.7. In the present invention, the Mooney viscosity [ML(1+4)100°C] is measured in accordance with JIS K6300-1 using a Mooney viscometer using an L-shaped rotor, with a preheating time of 1 minute, a rotor rotation time of 4 minutes, and a test temperature of 100°C. By setting the Mooney viscosity of the coating layer 23 appropriately relative to the adjacent rubber component in this manner, the rubber flow in the coating layer 23 during vulcanization is improved, and vulcanization failure is less likely to occur even if a gap occurs between the coating layer 23 and the adjacent rubber component.

[0039] Here, if the ratio of the Mooney viscosity of the covering layer 23 to the Mooney viscosity of the adjacent rubber member is smaller than 0.3, the rubber flow of the covering layer 23 during vulcanization will be excessively good, and there is a risk of exposing the transponder 20, and contact with the adjacent rubber member will deteriorate the communication performance of the transponder 20. Conversely, if the ratio of the Mooney viscosity of the covering layer 23 to the Mooney viscosity of the adjacent rubber member is larger than 0.9, the rubber flow of the covering layer 23 will deteriorate during vulcanization, making it easier for gaps to form between the covering layer 23 and the adjacent rubber member, and thus making the tire more susceptible to vulcanization failure.

[0040] Alternatively, the minimum value M in the vulcanization curve obtained from torque detection by a rheometer in the coating layer 23 Lc is the minimum value M in the vulcanization curve obtained by detecting torque by a rheometer in the rubber member disposed adjacent to the coating layer 23. Lt More preferably, the minimum value M Lc and the minimum value M of the adjacent rubber material Lt That is, 0.2≦M Lc / M Lt <1.0. By appropriately setting the viscosity of the coating layer 23 in this way, the rubber flow of the coating layer 23 during vulcanization is improved and gaps are less likely to occur between the coating layer 23 and the adjacent rubber member, making it possible to effectively suppress vulcanization failures in tires. In the present invention, the vulcanization curve obtained by torque detection using a rheometer is measured in accordance with JIS K6300-2, at a temperature of 170°C, with the obtained torque on the vertical axis and the vulcanization time on the horizontal axis. In this vulcanization curve, the minimum torque value is M L It is.

[0041] Here, the minimum value M of the coating layer 23 Lc and the minimum value M of the adjacent rubber material Lt If M is below the lower limit of the above relational expression, the rubber flow of the coating layer 23 becomes excessively good during vulcanization, and the transponder 20 may be exposed. If the transponder 20 comes into contact with an adjacent rubber member, the communication performance of the transponder 20 may deteriorate. Lc and the minimum value M of the adjacent rubber material LtIf the upper limit of the above relational expression is exceeded, the rubber flow of the covering layer 23 during vulcanization will deteriorate, and gaps will be more likely to occur between adjacent rubber members, making the tire more susceptible to vulcanization failure.

[0042] In the above-mentioned method for manufacturing a pneumatic tire, the width w of the step 24 (see FIG. 4(b)) is preferably 1.5 mm to 5.0 mm. The width w of the step is the average value of widths measured at three points, namely, both ends in the longitudinal direction of the covering layer 23 and the center of the covering layer 23. By appropriately setting the width w of the step in this manner, vulcanization failure of the tire can be effectively suppressed, and the durability of the tire can be improved.

[0043] Here, if the step width w is smaller than 1.5 mm, the effect of improving tire vulcanization failure cannot be sufficiently obtained, and tire durability deteriorates due to tire vulcanization failure. If the step width w is larger than 5.0 mm, the gap between the coating layer 23 and the adjacent rubber member becomes large, so the effect of improving tire vulcanization failure cannot be sufficiently obtained, and tire durability deteriorates due to tire vulcanization failure.

[0044] The thickness t of at least one of the front layer 23x and the back layer 23y (see FIG. 4(b)) is preferably 0.5 mm to 2.5 mm. The thickness t of the covering layer 23 is measured by dividing the covering layer 23 in the thickness direction with the center line of the transponder 20 as the boundary, that is, the thickness of the front layer 23x or the thickness of the back layer 23y. Note that when the covering layer 23 is made up of three or more layers, it is measured as described above.

[0045] Here, if the thickness t of the covering layer 23 is thinner than 1.5 mm, the communication performance of the transponder 20 deteriorates, but tire vulcanization failures around the transponder 20 can be suppressed. If the thickness t of the covering layer 23 is thicker than 2.5 mm, the communication performance of the transponder 20 improves, but tire vulcanization failures become more likely to occur, and tire durability deteriorates accordingly. By setting the thickness t of the covering layer 23 within the above range, tire vulcanization failures can be effectively suppressed.

[0046] In the above-mentioned method for manufacturing a pneumatic tire, it is preferable that the dielectric constant of the covering layer 23 covering the transponder 20 is set lower than the dielectric constant of the rubber members (e.g., the inner liner layer 9, the bead filler 6, the sidewall rubber layer 12, the rim cushion rubber layer 13, and the coating rubber of the carcass layer 4) disposed adjacent to the covering layer 23, and that the total thickness Gac of the covering layer 23 and the maximum thickness Gar of the transponder 20 satisfy the relationship of 1.1≦Gac / Gar≦3.0. The total thickness Gac of the covering layer 23 is the total thickness of the covering layer 23 at a position including the transponder 20, and is, for example, the total thickness on a straight line that passes through the center C of the transponder 20 and is perpendicular to the carcass cord of the nearest carcass layer 4 in the tire meridian cross section as shown in FIG. 7.

[0047] By setting the relative dielectric constant of the covering layer 23 in this manner and making the total thickness Gac of the covering layer 23 and the maximum thickness Gar of the transponder 20 satisfy the above relationship, the transponder 20 is sufficiently isolated from adjacent rubber members and is wrapped in the covering layer 23 with a low relative dielectric constant, thereby improving the communication performance of the transponder 20. In other words, when the wavelength of the radio wave of the communication device is λ and the relative dielectric constant of the covering layer 23 that covers the transponder 20 is ε r Then, the wavelength of the radio wave passing through the covering layer 23 is λ / √ε r Therefore, the length of the antenna 22 of the transponder 20 is the wavelength λ / √ε r The transponder 20 is set to resonate with the covering layer 23. By optimizing the length of the antenna 22 of the transponder 20 in this manner, the communication efficiency is significantly improved. However, in order to optimize the communication environment of the transponder 20, it is necessary to sufficiently isolate the transponder 20 from the adjacent rubber member adjacent to the covering layer 23. Therefore, by satisfying the relationship 1.1≦Gac / Gar≦3.0, it is possible to improve the communication performance of the transponder 20. Furthermore, by specifying the upper limit value of the total thickness Gac of the covering layer 23 with respect to the maximum thickness Gar of the transponder 20, it is possible to sufficiently ensure the durability of the tire. This makes it possible to improve the communication performance of the transponder 20 while ensuring the durability of the tire.

[0048] Here, if the above ratio is too small (the total thickness Gac of the covering layer 23 is too thin), the transponder 20 comes into contact with the adjacent rubber member, the resonant frequency shifts, and the communication performance of the transponder 20 deteriorates. Conversely, if the above ratio is too large (the total thickness Gac of the covering layer 23 is too thick), the durability of the tire tends to deteriorate.

[0049] In the above-described method for manufacturing a pneumatic tire, it is preferable that the center C of the transponder 20 in the thickness direction is disposed within a range of 25% to 75% of the total thickness Gac of the covering layer 23 from the surface on one side in the thickness direction of the covering layer 23, as shown in Fig. 7. This ensures that the transponder 20 is covered by the covering layer 23, so that the surrounding environment of the transponder 20 is stable, no deviation in the resonant frequency occurs, and a sufficient communication distance of the transponder 20 can be ensured.

[0050] Moreover, the composition of the coating layer 23 is preferably made of rubber or elastomer and 20 phr or more of white filler. 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 transponder 20 can be effectively improved. In this specification, "phr" means parts by weight per 100 parts by weight of the rubber component (elastomer).

[0051] The white filler constituting the coating layer 23 preferably contains 20 phr to 55 phr of calcium carbonate. This allows the relative dielectric constant of the coating layer 23 to be relatively low, and the communication properties of the transponder 20 to be effectively improved. However, if the white filler contains an excessive amount of calcium carbonate, the coating layer 23 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.

[0052] 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.

[0053] In the above-mentioned method for manufacturing a pneumatic tire, the transponder 20 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 5 mm inward in the tire radial direction from the terminal 7e of the belt layer 7 as the disposition area in the tire radial direction. That is, the transponder 20 is preferably disposed in the area S1 shown in FIG. 8. When the transponder 20 is disposed in the area S1, metal interference is unlikely to occur, and the communication performance of the transponder 20 can be ensured. Here, if the transponder 20 is disposed inward in the tire radial direction from the position P1, the transponder 20 and the adjacent rubber member are likely to peel off due to stress concentration near the rim flange, and the transponder 20 is likely to be close to the metal member such as the bead core 5, which tends to deteriorate the communication performance of the transponder 20. On the other hand, if the transponder 20 is disposed outward in the tire radial direction from the position P2, the transponder 20 is located in an area where the stress amplitude during running is large, and the transponder 20 itself is likely to be damaged and the interface peeling around the transponder 20 is likely to occur.

[0054] As shown in FIG. 9, there are a plurality of splice parts on the circumference of the tire, which are formed by overlapping the ends of tire constituent members. FIG. 9 shows the tire circumferential position Q of each splice part. The center of the transponder 20 is preferably disposed 10 mm or more away from the splice part of the tire constituent member in the tire circumferential direction. That is, the transponder 20 is preferably disposed in the region S2 shown in FIG. 9. Specifically, the substrate 21 constituting the transponder 20 is preferably disposed 10 mm or more away from the position Q in the tire circumferential direction. Furthermore, it is more preferable that the entire transponder 20 including the antenna 22 is disposed 10 mm or more away from the position Q in the tire circumferential direction, and it is most preferable that the entire transponder 20 covered with the covering rubber is disposed 10 mm or more away from the position Q in the tire circumferential direction. Moreover, the tire constituent member in which the splice part is disposed away from the transponder 20 is preferably a member adjacent to the transponder 20. Examples of such tire components include a carcass layer 4, a bead filler 6, a belt layer 7, an inner liner layer 9, a cap tread rubber layer 11, a sidewall rubber layer 12, and a rim cushion rubber layer 13. By disposing the transponder 20 at a position separated from the splice portion of the tire components, the durability of the tire can be effectively improved.

[0055] 9, 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 transponder 20 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.

[0056] Fig. 10 shows a modified example of a pneumatic tire to which the manufacturing method of a pneumatic tire according to the present invention is applied. In Fig. 10, the same parts as those in Fig. 1 and Fig. 2 are given the same reference numerals and detailed description of those parts is omitted.

[0057] As shown in FIG. 10, the transponder 20 is embedded in a portion on the outer side of the carcass layer 4 in the tire width direction. Specifically, the transponder 20 is disposed between the wound-up portion 4B of the carcass layer 4 and the rim cushion rubber layer 13. When manufacturing a pneumatic tire in which the transponder 20 is embedded in a portion on the outer side of the carcass layer 4 in the tire width direction, the inner liner layer 9 is placed on a molding drum, and tire components consisting of the carcass layer 4, the bead core 5, the bead filler 6, the belt layer 7, and the belt cover layer 8 are laminated thereon, and the cap tread rubber layer 11, the sidewall rubber layer 12, and the rim cushion rubber layer 13 are bonded together to form an unvulcanized tire, which is then vulcanized to manufacture the tire. When forming the unvulcanized tire, the transponder 20 covered with the covering layer 23 is disposed, for example, between the carcass layer 4 and the sidewall rubber layer 12 or the rim cushion rubber layer 13. Even with the above-mentioned method for manufacturing a pneumatic tire, it is possible to reduce the gap generated between the covering layer 23 and the rubber member (e.g., the sidewall rubber layer 12, the rim cushion rubber layer 13, etc.) disposed adjacent to the covering layer 23 by step 24. This makes it possible to suppress vulcanization failure of the tire around the transponder 20.

[0058] In the embodiment of Fig. 10, an example in which the transponder 20 is disposed between the turned-up portion 4B of the carcass layer 4 and the rim cushion rubber layer 13 is shown, but the present invention is not limited to this. Alternatively, the transponder 20 can be disposed between the main body portion 4A of the carcass layer 4 and the sidewall rubber layer 12. The end 4e of the turned-up portion 4B of the carcass layer 4 may be disposed in the middle of the sidewall portion 2, or the end 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.

[0059] In the above-described embodiment, an example in which the step 24 is formed only at one end of the width direction of the coating layer 23 has been shown, but the present invention is not limited to this. When forming the step 24, the step 24 may be formed at both ends of the width direction of the coating layer 23 as shown in FIG. 11(a), a plurality of steps 24 may be formed at both ends of the width direction of the coating layer 23 as shown in FIG. 11(b), a step 24 consisting of an inclined surface may be formed at both ends of the width direction of the coating layer 23 as shown in FIG. 11(c), or a step 24 combining an inclined surface and a flat surface may be formed at both ends of the width direction of the coating layer 23 as shown in FIG. 11(d). Furthermore, these may be combined, and a step 24 having an asymmetric shape may be provided on both sides of the width direction of the coating layer 23.

[0060] Furthermore, when forming steps 24, as shown in Figure 11(e), steps 24 can be formed by shifting the positions of the widthwise ends of two coating layers 23 having the same width, or as shown in Figure 11(f), steps 24 can be formed not only at the widthwise ends of coating layer 23, but also at one end of coating layer 23 in the longitudinal direction, or as shown in Figures 11(g) and (h), steps 24 can be formed at both widthwise ends of coating layer 23 and both lengthwise ends of coating layer 23. EXAMPLES

[0061] In a manufacturing method for a pneumatic tire having a tire size of 245 / 35R21 and having a transponder embedded in the tire, the transponder was coated with a coating layer, the transponder coated with the coating layer was embedded in an unvulcanized tire, and the unvulcanized tire was vulcanized. Tires of a conventional example and examples 1 to 13 were manufactured with the presence or absence of steps in the coating layer, the width of the steps in the coating layer, Gac / Gar, the material of the coating layer, the relative dielectric constant of the coating layer, the circumferential position of the transponder in the tire, and the radial position of the transponder in the tire set as shown in Table 1.

[0062] In the conventional example and Examples 1 to 13, the transponder is embedded between the carcass layer and the inner liner layer, and the relative dielectric constant of the coating layer that covers the transponder is set lower than that of the rubber member (the coating rubber of the inner liner layer and the carcass layer) arranged adjacent to the coating layer.

[0063] In Table 1, the circumferential position of the transponder indicates the distance [mm] measured in the circumferential direction of the tire from the center of the transponder to the splice of the tire constituent member. The radial positions of the transponder correspond to the positions A to C shown in FIG.

[0064] For these test tires, tire evaluation (vulcanization failure and durability) and transponder evaluation (communication performance) were carried out by the following test methods. The results are shown in Table 1.

[0065] Vulcanization failure: 200 of each test tire were manufactured, and the occurrence of vulcanization failures around the transponder was visually checked to calculate the occurrence rate of vulcanization failures. The evaluation results were shown in three stages: "◎ (excellent)" if there were no vulcanization failures, "○ (good)" if the occurrence rate of vulcanization failures was less than 3%, and "△ (fair)" if the occurrence rate of vulcanization failures was 3% or more.

[0066] Durability (Tires): Each test tire was mounted on a standard rim wheel and a running test was conducted on a drum testing machine under conditions of 120kPa air pressure, 102% of the maximum load, and a running speed of 81km, after which the running distance when the tire broke down was measured.The evaluation results were shown on a three-point scale: when the running distance reached 6,480km, it was indicated as "◎ (Excellent)", when the running distance was between 4,050km and 6,480km, it was indicated as "○ (Good)", and when the running distance was less than 4,050km, it was indicated as "△ (Fair)".

[0067] Communication (Transponder): A reader / writer was used to communicate with the transponder for each test tire. Specifically, the longest communication distance was measured with the reader / writer at an output of 250mW and a carrier frequency of 860MHz to 960MHz. The evaluation results were shown on a three-level scale: a communication distance of 1000mm or more was indicated as "◎ (excellent)", a communication distance of 500mm or more but less than 1000mm was indicated as "○ (good)", and a communication distance of less than 500mm was indicated as "△ (fair)".

[0068] [Table 1]

[0069] As can be seen from Table 1, the pneumatic tires of Examples 1 to 13 were able to suppress the occurrence of vulcanization failures in tires compared to the conventional tires. Furthermore, the pneumatic tires of Examples 1 to 7 and 9 to 13 were able to improve tire durability compared to the conventional tires, and the pneumatic tires of Examples 5 to 13 were able to improve transponder communication performance compared to the conventional tires. [Explanation of symbols]

[0070] 1 Tread section 2 Sidewall 3 Bead section 4 Carcass layer 5 Bead Core 6 Bead Filler 7 Belt layer 12 Sidewall rubber layer 13 Rim cushion rubber layer 20 Transponder 23 Covering layer 23a~23d End 23x surface layer 23y back layer 24 Steps CL Tire centerline

Claims

1. A method for manufacturing a pneumatic tire in which a transponder is embedded in the tire, comprising: a covering layer that covers the transponder has a surface layer located on the surface side of the transponder in the thickness direction and a surface layer located on the surface side of the transponder, and a step is formed at at least one of both ends in the width direction of the covering layer so that the end positions of the surface layer and the surface layer do not coincide with each other, and when the transponder covered with the covering layer having the step is embedded in an unvulcanized tire, the transponder is positioned so that the longitudinal direction of the transponder is within a range of ±10° with respect to the circumferential direction of a building drum, and the unvulcanized tire is vulcanized.

2. 2. The method for manufacturing a pneumatic tire according to claim 1, wherein the step is formed by shifting end positions of the surface layer and the back layer at at least one end of both ends in the width direction of the covering layer when sandwiching the transponder between the surface layer and the back layer.

3. The method for manufacturing a pneumatic tire according to claim 1 or 2, wherein the steps are formed at both ends in a width direction of the covering layer.

4. The method for manufacturing a pneumatic tire according to any one of claims 1 to 3, characterized in that the width of the step is 1.5 mm to 5.0 mm.

5. The method for manufacturing a pneumatic tire according to any one of claims 1 to 4, characterized in that at least one of the surface layer and the back layer has a thickness of 0.5 mm to 2.5 mm.

6. The method for manufacturing a pneumatic tire according to any one of claims 1 to 5, characterized in that the dielectric constant of the covering layer is lower than the dielectric constant of a rubber member disposed adjacent to the covering layer, and a total thickness Gac of the covering layer and a maximum thickness Gar of the transponder satisfy a relationship of 1.1≦Gac / Gar≦3.

0.

7. 7. The method for producing a pneumatic tire according to claim 1, wherein the covering layer is made of an elastomer or rubber, and the covering layer has a relative dielectric constant of 7 or less.

8. 8. The method for manufacturing a pneumatic tire according to claim 1, wherein the cover layer has a Mooney viscosity lower than a Mooney viscosity of a rubber member disposed adjacent to the cover layer.

9. The minimum value M in the vulcanization curve obtained by detecting the torque of the coating layer using a rheometer Lc The minimum value M in the vulcanization curve obtained by detecting torque by a rheometer in a rubber member disposed adjacent to the coating layer Lt The method for producing a pneumatic tire according to any one of claims 1 to 7, characterized in that

10. 10. The method for manufacturing a pneumatic tire according to claim 1, wherein a center of the transponder is disposed 10 mm or more away from a splice portion of a tire constituent member in a tire circumferential direction.

11. The method for manufacturing a pneumatic tire according to any one of claims 1 to 10, characterized in that the transponder is disposed between a position 15 mm outward in the tire radial direction from an upper end of a bead core of the bead portion and a position 5 mm inward in the tire radial direction from an end of a belt layer.

12. A method for manufacturing a pneumatic tire in which a transponder is embedded in the tire, comprising: a covering layer covering the transponder has a surface layer located on the surface side of the transponder in the thickness direction and a back layer located on the back side of the transponder, and a step is formed at at least one end of both ends in the width direction of the covering layer so that the end positions of the surface layer and the back layer do not coincide with each other, the transponder covered with the covering layer having the step is embedded in an unvulcanized tire, and the unvulcanized tire is vulcanized, a total thickness Gac of the covering layer and a maximum thickness Gar of the transponder satisfy the relationship: 1.1≦Gac / Gar≦3.

0.

13. A method for manufacturing a pneumatic tire in which a transponder is embedded in the tire, comprising: a covering layer covering the transponder has a surface layer located on the surface side of the transponder in the thickness direction and a back layer located on the back side of the transponder, and a step is formed at at least one end of both ends in the width direction of the covering layer so that the end positions of the surface layer and the back layer do not coincide with each other, the transponder covered with the covering layer having the step is embedded in an unvulcanized tire, and the unvulcanized tire is vulcanized, A method for manufacturing a pneumatic tire, wherein the cover layer has a Mooney viscosity lower than the Mooney viscosity of a rubber member disposed adjacent to the cover layer.

14. A method for manufacturing a pneumatic tire in which a transponder is embedded in the tire, comprising: a covering layer covering the transponder has a surface layer located on the surface side of the transponder in the thickness direction and a back layer located on the back side of the transponder, and a step is formed at at least one end of both ends in the width direction of the covering layer so that the end positions of the surface layer and the back layer do not coincide with each other, the transponder covered with the covering layer having the step is embedded in an unvulcanized tire, and the unvulcanized tire is vulcanized, A method for manufacturing a pneumatic tire, characterized in that a minimum value M Lc in a vulcanization curve obtained from torque detection by a rheometer in the coating layer is lower than a minimum value M Lt in a vulcanization curve obtained from torque detection by a rheometer in a rubber member arranged adjacent to the coating layer.

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