pneumatic tires

Abstract

To provide a pneumatic tire which can secure the communication property of a transponder.SOLUTION: A transponder 20 which extends along a tire circumferential direction is embedded between a position P1 at 15 mm on the tire radial direction outer side from an upper end 5e of a bead core 5 and a position P2 at 5 mm on the tire radial direction inner side from a terminal 7e of a belt layer 7. An amount of silicon of a release agent detected by a fluorescent X-ray spectroscopy on a tire inner surface corresponding to at least the embedded position of the transponder 20 is equal to or less than 10.0 wt.%, or the thickness of the release agent detected by an electron microscope is equal to or less than 100 μm.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pneumatic tire having a transponder embedded therein, and more particularly to a pneumatic tire that makes it possible to ensure the communication performance of the transponder. [Background technology]

[0002] In pneumatic tires, when a green tire is vulcanized using a bladder, the bladder tends to stick to the inner surface of the green tire, so a release agent is applied to the inner surface of the green tire to prevent sticking between the green tire and the bladder. Generally, release agents contain materials such as carbon, mica, and silicone, and among these materials, carbon has the property of easily reflecting radio waves.

[0003] When a transponder is embedded inside such a pneumatic tire (see, for example, Patent Document 1), there is a problem that when communicating with the transponder using a reader / writer, radio waves are reflected by the layer of release agent formed on the inner surface of the tire, causing the radio waves to cancel each other out, reducing the communication distance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-137510 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a pneumatic tire that can ensure the communication performance of a transponder. [Means for solving the problem]

[0006] In order to achieve the above object, the pneumatic tire of the present invention comprises a tread portion extending in a circumferential direction of the tire to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged radially inward of the sidewall portions, wherein a bead filler is arranged on the outer periphery of the bead core of each bead portion, at least one carcass layer is mounted between the pair of bead portions, a plurality of belt layers are arranged on the outer periphery of the carcass layer in the tread portion, and an inner liner layer is arranged adjacent to the carcass layer in the sidewall portions and along the carcass layer, and wherein a transponder extending in a circumferential direction of the tire is embedded between a position 15 mm outward from the upper end of the bead core in the radial direction of the tire and a position 5 mm inward from the end of the belt layer, and the amount of silicon in the release agent detected by fluorescent X-ray analysis at least in the inner surface of the tire corresponding to the embedded position of the transponder is 0.1% by weight to 10.0% by weight, and the release agent is carbon does not contain It is characterized by the following.

[0007] Further, a pneumatic tire of the present invention includes a tread portion extending in a tire circumferential direction and forming an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged radially inward of the sidewall portions, wherein a bead filler is arranged on the outer periphery of a bead core of each bead portion, at least one carcass layer is mounted between the pair of bead portions, a plurality of belt layers are arranged on the outer periphery of the carcass layer in the tread portion, and an inner liner layer is arranged adjacent to the carcass layer in the sidewall portions and along the carcass layer, and wherein a transponder extending along the tire circumferential direction is embedded between a position 15 mm outward from an upper end of the bead core in the tire radial direction and a position 5 mm inward from an end of the belt layer in the tire radial direction, and the thickness of a release agent detected by an electron microscope at least on the tire inner surface corresponding to the embedded position of the transponder is 0.1 μm to 100 μm, and the release agent is a carbon does not contain It is characterized by the following. [Effects of the Invention]

[0008] The inventors of the present invention discovered that, in order to ensure the communication performance of a transponder, it is effective to specify the amount or thickness of the release agent adhered to the inner surface of a tire, and arrived at the present invention.

[0009] In the present invention, the transponder extending along the tire circumferential direction is embedded between a position 15 mm radially outward from the upper end of the bead core and a position 5 mm radially inward from the end of the belt layer, making it difficult for metal interference to occur and ensuring transponder communication performance. In particular, at least on the tire inner surface corresponding to the location where the transponder is embedded, the amount of silicon in the release agent detected by X-ray fluorescence analysis is 10.0% by weight or less, or the thickness of the release agent detected by electron microscope is 100 μm or less. Therefore, the amount of release agent adhering to the tire inner surface is small, making it possible to suppress cancellation of radio waves during communication caused by the release agent, thereby contributing to improved transponder communication performance.

[0010] In the pneumatic tire of the present invention, it is preferable that the amount of silicon in the release agent is 0.1% by weight to 10.0% by weight, or that the thickness of the release agent is 0.1 μm to 100 μm. For example, the release agent on the tire inner surface can be completely removed by buffing the tire inner surface after vulcanization, or by applying a film to the inner surface of a green tire in advance, applying a release agent to the inner surface of the green tire with the film still attached, and then peeling off the film after vulcanization. However, there is a concern that this may deteriorate the air retention of the tire. In contrast, it is possible to ensure transponder communication without significantly deteriorating air retention.

[0011] The center of the transponder is preferably located 10 mm or more away from the splice portion of the tire constituent members in the tire circumferential direction, which can effectively improve tire durability.

[0012] The transponder is preferably disposed between the carcass layer and a rubber layer disposed outside the carcass layer in the sidewall portion so as to abut against the rubber layer, thereby suppressing attenuation of radio waves during communication and effectively improving the communication performance of the transponder.

[0013] The distance between the cross-sectional center of the transponder and the outer surface of the tire is preferably 2 mm or more, which can effectively improve the durability of the tire and improve the tire's resistance to external damage.

[0014] In a pneumatic tire having an inner liner layer disposed on the inner surface of the tire along the carcass layer, the transponder is preferably disposed between the carcass layer and the inner liner layer. If the transponder is disposed on the outer side of the turned-up portion of the carcass layer in the tire width direction, the transponder may be damaged in conjunction with damage to the sidewall portion, but damage to the transponder caused by damage to the sidewall portion can be prevented.

[0015] The distance between the cross-sectional center of the transponder and the inner surface of the tire is preferably 1 mm or more, which can effectively improve tire durability and prevent damage to the transponder that may result from damage to the inner liner layer when the tire is assembled to the rim.

[0016] The transponder is preferably disposed between a position 5 mm outward in the tire radial direction from the top end of the bead filler and a position 5 mm inward in the tire radial direction from the end of the belt layer. This allows the transponder to be disposed in the flex zone where the rubber gauge is thin, and this region experiences little attenuation of radio waves during transponder communication, effectively improving the transponder's communication performance.

[0017] The transponder is preferably covered with a covering layer, and the covering layer has a relative dielectric constant of 7 or less. This protects the transponder with the covering layer, improving the durability of the transponder, and also ensuring the radio wave transparency of the transponder and sufficient communication performance of the transponder.

[0018] The transponder is covered with a covering layer, and the thickness of the covering layer is preferably 0.5 mm to 3.0 mm, which can sufficiently ensure the communication performance of the transponder without causing irregularities on the outer or inner surface of the tire.

[0019] The transponder has an IC board for storing data and an antenna for transmitting and receiving data, and the antenna is preferably spiral, which allows it to follow the deformation of the tire during driving and improves the durability of the transponder. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a meridian half cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. [Figure 2] FIG. 2 is a meridian cross-sectional view schematically showing the pneumatic tire of FIG. 1. [Figure 3] FIG. 2 is an equatorial cross-sectional view schematically showing the pneumatic tire of FIG. [Figure 4] 2 is an enlarged cross-sectional view showing a transponder embedded in the pneumatic tire of FIG. 1. FIG. [Figure 5] 1(a) and 1(b) are perspective views showing a transponder that can be embedded in a pneumatic tire according to the present invention. [Figure 6] FIG. 10 is a meridian half cross-sectional view showing a modified example of a pneumatic tire according to an embodiment of the present invention. [Figure 7] FIG. 7 is an enlarged cross-sectional view showing a transponder embedded in the pneumatic tire of FIG. 6. [Figure 8] FIG. 2 is an explanatory diagram showing the radial position of a transponder in a test tire. DETAILED DESCRIPTION OF THE INVENTION

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which: Figures 1 to 4 show a pneumatic tire according to an embodiment of the present invention.

[0022] As shown in FIG. 1, the pneumatic tire of this embodiment includes a tread portion 1 extending circumferentially of the tire to form an annular shape, a pair of sidewall portions 2 arranged on both sides of the tread portion 1, and a pair of bead portions 3 arranged radially inward of the sidewall portions 2.

[0023] At least one carcass layer 4 (one layer in FIG. 1) made up of a plurality of carcass cords arranged in the radial direction is mounted between a pair of bead portions 3. Organic fiber cords such as nylon or polyester are preferably used as the carcass cords that make up the carcass layer 4. 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.

[0024] Meanwhile, multiple belt layers 7 (two layers in FIG. 1) are embedded on the tire outer circumferential side of the carcass layer 4 in the tread portion 1. The belt layers 7 include multiple reinforcing cords that are inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. In the belt layers 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. Steel cords are preferably used as the reinforcing cords of the belt layers 7.

[0025] At least one belt cover layer 8 (two layers in FIG. 1 ) is disposed on the tire outer circumferential side of the belt layer 7, with the aim of improving high-speed durability, and the belt cover layer 8 has reinforcing cords arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction. In FIG. 1 , the belt cover layer 8 located on the inner side in the tire radial direction constitutes a full cover that covers the entire width of the belt layer 7, while the belt cover layer 8 located on the outer side in the tire radial direction constitutes an edge cover layer that covers only the ends 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.

[0026] In the 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 arranged to encase the bead cores 5 and the bead fillers 6. The carcass layer 4 includes a main body portion 4A that extends from the tread portion 1 through each sidewall portion 2 to each bead portion 3, and a turned-up portion 4B that is turned up around the bead core 5 in each bead portion 3 and extends toward each sidewall portion 2.

[0027] Additionally, an inner liner layer 9 is disposed on the tire inner surface along the carcass layer 4. A cap tread rubber layer 11 is disposed in the tread portion 1, a sidewall rubber layer 12 is disposed in the sidewall portion 2, and a rim cushion rubber layer 13 is disposed in the bead portion 3. A rubber layer 10 disposed outside the carcass layer 4 in the sidewall portion 2 includes the sidewall rubber layer 12 and the rim cushion rubber layer 13.

[0028] In the pneumatic tire, the transponder 20 is embedded between a position P1 that is 15 mm radially outward from the upper end 5e (the outer end in the tire radial direction) of the bead core 5 and a position P2 that is 5 mm radially inward from the terminal 7e of the belt layer 7. That is, the transponder 20 is disposed in an area S1 shown in Fig. 2. The transponder 20 extends along the tire circumferential direction. The transponder 20 may be disposed so as to be inclined in the range of -10° to 10° with respect to the tire circumferential direction.

[0029] 1 and 2 show an example in which the terminal end 4e of the turned-up portion 4B of the carcass layer 4 is arranged midway between the sidewall portion 2, but the terminal end 4e of the turned-up portion 4B of the carcass layer 4 may be arranged to the side of the bead core 5. In such a rolled-up structure, the transponder 20 may be arranged between the carcass layer 4 (more specifically, the bead filler 6) and the sidewall rubber layer 12 or the rim cushion rubber layer 13 while abutting against the rubber layer.

[0030] An example of the transponder 20 that can be used is an RFID (Radio Frequency Identification) tag. As shown in FIGS. 5(a) and 5(b), the transponder 20 has an IC board 21 that stores data and an antenna 22 that transmits and receives data in a contactless manner. By using such a transponder 20, tire-related information can be written or read as needed, enabling efficient tire management. RFID is an automatic identification technology that is composed of a reader / writer with an antenna and a controller, and an ID tag with an IC board and an antenna, and is capable of wirelessly communicating data.

[0031] 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 FIGS. 5(a) and 5(b). In particular, the columnar transponder 20 shown in FIG. 5(a) is suitable because it can adapt to tire deformation in all directions. 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 it to adapt to tire deformation during running, improving the durability of the transponder 20. Furthermore, communication performance can be ensured by appropriately changing the length of the antenna 22.

[0032] Furthermore, in the pneumatic tire, the amount of silicon in the release agent is 10.0% by weight or less at least in the tire inner surface corresponding to the location where the transponder 20 is embedded. In the present invention, the amount of release agent in the tire inner surface is specified using the amount of silicon, which is the main component of general release agents, as an indicator. This amount of silicon can be detected using X-ray fluorescence analysis. X-ray fluorescence analysis generally includes the FP method (fundamental parameter method) and the calibration curve method, but the FP method is used in the present invention. To measure the amount of release agent (silicon), sheet samples (70 mm wide, 100 mm long) were obtained by removing the carcass layer and inner liner layer from multiple locations on the pneumatic tire (e.g., seven locations: four circumferentially and three widthwise). Five measurement samples (13-15 mm wide, 35-40 mm long) were then extracted from each sheet sample: four corner locations and one central location. The amount of release agent in each sample was measured using an X-ray fluorescence analyzer. The measured values ​​for the five measurement samples were then averaged to calculate the amount of release agent for each sheet sample, and each calculated value was 10.0 wt% or less. Furthermore, fluorescent X-ray particles have a specific energy proportional to their atomic number, and measuring this specific energy allows the element to be identified. Specifically, the specific energy of silicon is 1.74±0.05 keV. The number of fluorescent X-ray particles (X-ray intensity) of the release agent (silicon) is in the range of 0.1 cps / μA to 1.5 cps / μA.

[0033] Alternatively, the thickness of the release agent is 100 μm or less at least on the tire inner surface corresponding to the location where the transponder 20 is embedded. The thickness of this release agent can be detected using an electron microscope. When measuring the thickness of the release agent using an electron microscope, a sample cut out from the pneumatic tire along the tire width direction is used, and the thickness is measured at multiple locations on the sample (for example, four locations in the tire circumferential direction and three locations in the tire width direction). The measured values ​​measured at the multiple locations are then averaged to calculate the thickness (average thickness) of the release agent.

[0034] While it is preferable to use a release agent that does not contain carbon, it is also preferable to use a release agent with a carbon content of less than 5% by weight. In particular, it is preferable to use a release agent that contains an insulator composed of silicone, mica, and talc, and in which the silicone content of the insulator is 80% by weight or more. Examples of silicone components include organopolysiloxanes, such as dialkylpolysiloxane, alkylphenylpolysiloxane, alkylaralkylpolysiloxane, and 3,3,3-trifluoropropylmethylpolysiloxane. Examples of dialkylpolysiloxanes include dimethylpolysiloxane, diethylpolysiloxane, methylisopropylpolysiloxane, and methyldodecylpolysiloxane. Examples of alkylphenylpolysiloxanes include methylphenylpolysiloxane, dimethylsiloxane-methylphenylsiloxane copolymer, and dimethylsiloxane-diphenylsiloxane copolymer. Examples of alkylaralkylpolysiloxanes include methyl(phenylethyl)polysiloxane and methyl(phenylpropyl)polysiloxane. These organopolysiloxanes may be used alone or in combination of two or more.

[0035] In the pneumatic tire described above, the transponder 20 is embedded extending along the tire circumferential direction between a position P1 that is 15 mm outward in the tire radial direction from the upper end 5e of the bead core 5 and a position P2 that is 5 mm inward in the tire radial direction from the terminal 7e of the belt layer 7, making it difficult for metal interference to occur and ensuring the communication performance of the transponder 20. In particular, at least on the tire inner surface corresponding to the location where the transponder 20 is embedded, the amount of silicon in the release agent detected by X-ray fluorescence analysis is 10.0% by weight or less, or the thickness of the release agent detected by electron microscope is 100 μm or less. Therefore, the amount of release agent adhering to the tire inner surface is small, making it possible to suppress cancellation of radio waves during communication caused by the release agent, thereby contributing to improving the communication performance of the transponder 20.

[0036] If the transponder 20 is disposed radially inward of position P1, metallic interference with the rim flange occurs, which tends to reduce the communication performance of the transponder 20. If the transponder 20 is disposed radially outward of position P2, metallic interference with the belt layer 7 occurs, which tends to reduce the communication performance of the transponder 20.

[0037] In the pneumatic tire, the amount of silicon in the release agent is preferably 0.1 wt % to 10.0 wt %, or the thickness of the release agent is preferably 0.1 μm to 100 μm. For example, the release agent on the tire inner surface can be completely removed by buffing the tire inner surface after vulcanization, or by applying a film to the inner surface of the green tire in advance, applying a release agent to the inner surface of the green tire with the film still attached, and then peeling off the film after vulcanization. However, there is a concern that this may deteriorate the air retention of the tire. In contrast, the communication performance of the transponder 20 can be ensured without significantly deteriorating the air retention.

[0038] In the above pneumatic tire, the transponder 20 is preferably disposed between the carcass layer 4 and the rubber layer 10 so as to abut against the rubber layer 10. That is, the transponder 20 is preferably disposed in the tire width direction between the carcass layer 4 and the sidewall rubber layer 12 or the rim cushion rubber layer 13 so as to abut against the rubber layer. When the transponder 20 is disposed in this manner, attenuation of radio waves during communication is suppressed, and the communication performance of the transponder 20 can be effectively improved.

[0039] The transponder 20 is preferably disposed between a position P3 that is 5 mm radially outward from the upper end 6e of the bead filler 6 and a position P2 that is 5 mm radially inward from the terminal 7e of the belt layer 7. That is, the transponder 20 is preferably disposed in an area S2 shown in Fig. 2. The area S2 is a flex zone where the rubber gauge is thin, and when the transponder 20 is disposed in the area S2, attenuation of radio waves during communication by the transponder 20 is reduced, and the communication performance of the transponder 20 can be effectively improved.

[0040] As shown in FIG. 3, there are multiple splice portions around the tire, each formed by overlapping the ends of tire constituent members. FIG. 3 also shows the circumferential position Q of each splice portion. The center of the transponder 20 is preferably positioned at a distance of 10 mm or more in the tire circumferential direction from the splice portion of the tire constituent members. That is, the transponder 20 is preferably positioned in the region S3 shown in FIG. 3. Specifically, the IC substrate 21 constituting the transponder 20 is preferably positioned at a distance of 10 mm or more in the tire circumferential direction from the position Q. Furthermore, it is more preferable that the entire transponder 20, including the antenna 22, is positioned at a distance of 10 mm or more in the tire circumferential direction, and it is most preferable that the entire transponder 20, covered with the covering rubber, is positioned at a distance of 10 mm or more in the tire circumferential direction from the position Q. Furthermore, the tire constituent member positioned at a distance from the transponder 20 is preferably the inner liner layer 9, the carcass layer 4, the sidewall rubber layer 12, or the rim cushion rubber layer 13, which may be positioned adjacent to the transponder 20. By disposing the transponder 20 away from the splice portion of the tire constituent members in this way, the durability of the tire can be effectively improved.

[0041] 3, an example is shown in which the positions Q of the splices of the tire constituent members in the tire circumferential direction are arranged at equal intervals, but the present invention is not limited to this. The positions Q of the tire circumferential direction can be set at any position, and in any case, the transponder 20 is arranged so as to be spaced 10 mm or more in the tire circumferential direction from the splices of the tire constituent members.

[0042] 4, the distance d1 between the center of the cross section of the transponder 20 and the outer surface of the tire is preferably 2 mm or more. By separating the transponder 20 from the outer surface of the tire in this manner, it is possible to effectively improve the durability of the tire and also improve the tire's resistance to external damage.

[0043] Furthermore, the transponder 20 is preferably covered with a covering layer 23. This covering layer 23 covers the entire transponder 20 by sandwiching both the front and back sides of the transponder 20. The covering layer 23 may be made of rubber having the same physical properties as the rubber that constitutes the sidewall rubber layer 12 or the rim cushion rubber layer 13, or may be made of rubber having different physical properties. By protecting the transponder 20 with the covering layer 23 in this way, the durability of the transponder 20 can be improved.

[0044] In the pneumatic tire described above, when the transponder 20 is covered with the covering layer 23, the covering layer 23 preferably has a relative permittivity of 7 or less, more preferably 2 to 5. By appropriately setting the relative permittivity of the covering layer 23 in this manner, radio wave transparency when the transponder 20 emits radio waves can be ensured, effectively improving the communication performance of the transponder 20. The relative permittivity 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 relative permittivity of the rubber is measured 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 range for UHF RFID. However, if the allocated frequency range is changed, the relative permittivity for the new allocated frequency range can be specified as described above.

[0045] Furthermore, when the transponder 20 is covered with the covering layer 23, the thickness t of the covering layer 23 is preferably 0.5 mm to 3.0 mm, and more preferably 1.0 mm to 2.5 mm. Here, the thickness t of the covering layer 23 is the rubber thickness at a position including the transponder 20. For example, as shown in FIG. 4 , it is the rubber thickness obtained by summing the thicknesses t1 and t2 on a line passing through the center of the transponder 20 and perpendicular to the tire outer surface. By appropriately setting the thickness t of the covering layer 23 in this manner, the communication performance of the transponder 20 can be effectively improved without causing irregularities on the tire outer surface or tire inner surface. Here, if the thickness t of the covering layer 23 is thinner than 0.5 mm, the improvement in the communication performance of the transponder 20 cannot be obtained. Conversely, if the thickness t of the covering layer 23 exceeds 3.0 mm, irregularities will occur on the tire outer surface or tire inner surface, which is undesirable. The cross-sectional shape of the covering layer 23 is not particularly limited, but may be, for example, a triangular, rectangular, trapezoidal, or spindle shape. The coating layer 23 in FIG. 4 has a substantially spindle-shaped cross section.

[0046] Figures 6 and 7 show modified examples of pneumatic tires according to the embodiments of the present invention. In Figures 6 and 7, the same components as those in Figures 1 to 4 are designated by the same reference numerals, and detailed descriptions of those components will be omitted.

[0047] As shown in Figure 6, a transponder 20 is embedded between the carcass layer 4 and the inner liner layer 9. If the transponder is disposed between the carcass layer and the sidewall rubber layer or the rim cushion rubber layer so as to abut against the rubber layer, the transponder may be damaged in conjunction with damage to the sidewall portion. In contrast, if the transponder 20 is embedded between the carcass layer 4 and the inner liner layer 9 as shown in Figure 6, damage to the transponder 20 caused by damage to the sidewall portion 2 can be prevented.

[0048] 7, the distance d2 between the center of the cross section of the transponder 20 and the tire inner surface is preferably 1 mm or more. By separating the transponder 20 from the tire inner surface in this manner, tire durability can be effectively improved and damage to the transponder 20 caused by damage to the inner liner layer 9 during assembly with the rim can be prevented.

[0049] In the above-described embodiment, an example of a pneumatic tire having one carcass layer is shown, but this is not particularly limited, and two carcass layers may be used. Also, in the above-described embodiment, an example is shown in which the end 4e of the turned-up portion 4B of the carcass layer 4 is disposed midway between the sidewall portion 2 and beyond the upper end 6e of the bead filler 6, but this is not limited, and the tire may be disposed at any height.

[0050] Next, a method for manufacturing a pneumatic tire of the present invention will be described. When vulcanizing a green tire, a release agent is first coated (preferably by baking) on ​​a bladder to form a coating layer made of the release agent on the outer surface of the bladder. The step of forming the coating layer on the outer surface of the bladder is carried out, for example, by storing the tire after application of the release agent at 150°C for 1 hour, at 90°C for 4 hours, or at room temperature for 8 hours. The step of forming the coating layer on the outer surface of the bladder is carried out at least once and no more than three times. A green tire is vulcanized using a bladder on which a coating layer has been formed in this manner. When a bladder provided with a coating layer made of the release agent is used for vulcanization, the release agent is transferred to the inner surface of the vulcanized pneumatic tire. In this transfer layer made of the release agent, the release agent is not transferred to the entire inner surface of the tire but is scattered throughout.

[0051] Instead of vulcanizing the tire using a bladder provided with a coating layer of a release agent as described above, a core can be used in the vulcanization step of the green tire. Alternatively, the release agent on the tire inner surface can be completely removed by buffing the tire inner surface after vulcanization, or by applying a film to the inner surface of the green tire in advance, applying a release agent to the inner surface of the green tire with the film still attached, and then peeling off the film after vulcanization.

[0052] As described above, by performing vulcanization using a bladder provided with a coating layer made of a release agent, or by performing vulcanization using a core, it is possible to reduce the amount of silicon in the release agent detected by X-ray fluorescence analysis to 10.0% by weight or less, or 100 μm or less, at least on the tire inner surface corresponding to the location where the transponder 20 is embedded. When the amount of release agent attached to the tire inner surface is small in this way, it is possible to suppress cancellation of radio waves during communication caused by the release agent, and the communication performance of the transponder 20 can be improved. [Example]

[0053] The tire size was 265 / 40ZR20, and the tire had a tread portion extending circumferentially in an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged radially inward of these sidewall portions. A bead filler was arranged on the outer periphery of the bead core of each bead portion, a carcass layer was mounted between the pair of bead portions, and multiple belt layers were arranged on the outer periphery of the carcass layer in the tread portion. In this pneumatic tire, a transponder extending along the tire circumferential direction was embedded, and the release agent (removal method and amount) and the position of the transponder (tire radial direction) were set as shown in Table 1. Tires of Comparative Examples 1 to 5 and Examples 1 to 6 were manufactured.

[0054] In Table 1, when the vulcanization method was "normal," vulcanization molding was performed using a normal bladder; when the vulcanization method was "core," vulcanization molding was performed using a core; and when the vulcanization method was "coated," vulcanization molding was performed using a bladder with a coating layer made of a release agent. In Table 1, the amount of release agent (silicon) adhering to the tire inner surface was calculated by averaging values ​​calculated based on the amount of release agent (silicon) measured at four circumferential locations and three widthwise locations of each test tire after the manufacturing process using an energy dispersive X-ray fluorescence analyzer (Shimadzu EDX-720). The measurement conditions were a vacuum, a voltage of 50 kV, a current of 100 μA, an integration time of 50 seconds, and a collimator diameter of 10 mm. Furthermore, in Table 1, the transponder positions (in the tire radial direction) correspond to positions A to F shown in Figure 8.

[0055] These test tires were subjected to tire evaluation (air retention) and transponder evaluation (communication performance) using the following test methods. The results are also shown in Table 1.

[0056] Air retention (tire): Each test tire was mounted on a standard rim wheel and left to stand for 24 hours at an air pressure of 270 kPa and a temperature of 21°C, after which the initial air pressure was set to 250 kPa and the air pressure was measured over 42 days, and the slope of the air leakage rate from the 15th to 42nd day was determined. The evaluation results were expressed as an index using the reciprocal of the measured value, with Comparative Example 2 being set at 100. A higher index value indicates better air retention.

[0057] Communication (Transponder): For each test tire, a reader / writer was used to carry out communication with the transponder. Specifically, the longest distance over which communication was possible 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 expressed as an index, with Comparative Example 2 being set to 100. A higher index value means better communication performance.

[0058] [Table 1]

[0059] As can be seen from Table 1, the transponder communication performance was improved in Examples 1 to 6. In Examples 3 to 6, a bladder provided with a coating layer made of a core or a release agent was used in the vulcanization process, and therefore the air retention of the tire was maintained.

[0060] On the other hand, in Comparative Example 1, vulcanization molding was performed using a normal bladder, which resulted in a deterioration in transponder communication performance. In Comparative Example 3, the tire inner surface was subjected to high-pressure cleaning after normal vulcanization molding, but a large amount of release agent remained on the tire inner surface, and this amount exceeded the amount specified in the present invention, resulting in a deterioration in transponder communication performance. In Comparative Example 4, the position of the transponder in the tire radial direction was outside the range specified in the present invention, resulting in a deterioration in transponder communication performance. In Comparative Example 5, the amount of release agent on the tire inner surface exceeded the amount specified in the present invention, resulting in no improvement in transponder communication performance.

[0061] Next, tires of Comparative Examples 6 to 10 and Examples 7 to 12 were manufactured in a pneumatic tire having a tread portion extending circumferentially in a ring shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged radially inward of these sidewall portions, with bead fillers arranged on the outer periphery of the bead core of each bead portion, a carcass layer mounted between the pair of bead portions, and multiple belt layers arranged on the outer periphery of the carcass layer in the tread portion.A transponder extending along the tire circumferential direction was embedded in the pneumatic tire, and the release agent (removal method and thickness) and the position of the transponder (tire radial direction) were set as shown in Table 2.

[0062] In Table 2, the thickness [μm] of the release agent adhered to the tire inner surface was measured using a scanning electron microscope (SEM-EDX) at four locations in the tire circumferential direction and three locations in the tire width direction of each test tire after the manufacturing process, and the average of these measurements was calculated. In Table 2, the positions of the transponders (in the tire radial direction) correspond to the positions A to F shown in Figure 8.

[0063] These test tires were subjected to tire evaluation (air retention) and transponder evaluation (communication performance), and the results are shown in Table 2. In Table 2, the evaluation results of tire air retention and transponder communication performance are shown as indexes, with Comparative Example 7 being set at 100.

[0064] [Table 2]

[0065] As can be seen from Table 2, the transponder communication performance was improved in Examples 7 to 12. In Examples 9 to 12, a bladder provided with a coating layer made of a core or a release agent was used in the vulcanization process, and therefore the air retention of the tire was maintained.

[0066] On the other hand, in Comparative Example 6, vulcanization molding was performed using a normal bladder, which resulted in a deterioration in transponder communication performance. In Comparative Example 8, the tire inner surface was subjected to high-pressure cleaning after normal vulcanization molding, but a large amount of release agent remained on the tire inner surface, and this amount exceeded the amount specified in the present invention, resulting in a deterioration in transponder communication performance. In Comparative Example 9, the position of the transponder in the tire radial direction was outside the range specified in the present invention, resulting in a deterioration in transponder communication performance. In Comparative Example 10, the thickness of the release agent on the tire inner surface exceeded the amount specified in the present invention, resulting in no improvement in transponder communication performance.

[0067] Next, tires of Comparative Example 11 and Examples 13 to 31 were manufactured in a pneumatic tire having a tread portion extending circumferentially and forming an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged radially inward of these sidewall portions, with bead fillers arranged on the outer periphery of the bead core of each bead portion, a carcass layer mounted between the pair of bead portions, and multiple belt layers arranged on the outer periphery of the carcass layer in the tread portion.A transponder extending along the tire circumferential direction was embedded in the pneumatic tire, and the position of the transponder (tire width direction, tire radial direction, and tire circumferential direction), the distance between the transponder and the tire outer surface, the distance between the transponder and the tire inner surface, the relative permittivity of the coating layer, the thickness of the coating layer, and the shape of the transponder were set as shown in Tables 3 and 4.

[0068] Here, the tires of Comparative Example 11 and Examples 13 to 31 were vulcanized using a bladder provided with a coating layer made of a release agent, and the amount of release agent (silicon) adhering to the inner surface of the tire was 0.1 wt %.

[0069] In Tables 3 and 4, when the transponder position (tire width direction) is "W," the transponder is disposed between the bead filler and the carcass layer; when the transponder position (tire width direction) is "X," the transponder is disposed between the carcass layer and the inner liner layer; when the transponder position (tire width direction) is "Y," the transponder is disposed between the carcass layer and the sidewall rubber layer in contact with the sidewall rubber layer; and when the transponder position (tire width direction) is "Z," the transponder is disposed between the carcass layer and the rim cushion rubber layer in contact with the rim cushion rubber layer. Furthermore, in Tables 3 and 4, the transponder positions (tire radial direction) correspond to the positions A to F shown in FIG. 8. Furthermore, in Tables 3 and 4, the transponder position (tire circumferential direction) indicates the distance [mm] measured in the tire circumferential direction from the center of the transponder to the splice portion of the tire constituent member.

[0070] These test tires were evaluated using the following test methods (durability, resistance to external damage, and The results are shown in Tables 3 and 4. The evaluation results of the transponder communication performance are expressed as an index with Example 13 being 100.

[0071] Durability (tires and transponders): Each test tire was mounted on a standard rim wheel and subjected to a running test using a drum testing machine under conditions of 120 kPa air pressure, 102% of maximum load, and a running speed of 81 km. The running distance when the tire malfunctioned was then measured. The evaluation results were graded on a four-point scale: "Excellent" for a running distance of 6,480 km, "Good" for a running distance of 4,050 km to 6,480 km, "Fair" for a running distance of 3,240 km to 4,050 km, and "Poor" for a running distance of less than 3,240 km. Furthermore, the outer surface of each test tire was visually inspected after the run to determine whether the tire malfunction was caused by the transponder. The evaluation results indicated whether or not the malfunction occurred.

[0072] Trauma resistance (tires): Each test tire was mounted on a standard rim wheel and attached to a test vehicle, and a running test was conducted in which the tire was driven at an air pressure of 230 kPa and a running speed of 20 km / h while contacting a 100 mm high curb. After the run, the tire was visually inspected for damage to the outer surface. The evaluation results showed whether or not there was any damage to the outer surface of the tire.

[0073] Appearance (tire): For each test tire, the outer surface of the tire corresponding to the location of the transponder was visually inspected. The evaluation results were rated as "good" if there were no irregularities on the outer surface of the tire due to the placement of the transponder, and "poor" if there were irregularities.

[0074] Trauma Resistance (Transponder): Each test tire was mounted on a standard rim wheel and attached to a test vehicle, and a running test was conducted in which the tire ran over a 100mm high curb at an air pressure of 230kPa and a running speed of 20km / h. After the run, damage to the outer surface of the tire corresponding to the location of the transponder was checked. The evaluation results showed whether or not there was any damage to the outer surface of the tire due to the placement of the transponder.

[0075] Damage resistance during assembly (transponder): For each test tire, the inner surface of the tire corresponding to the location of the transponder was visually inspected when the rim was replaced. The evaluation results indicated whether or not the transponder had been damaged due to damage to the inner liner.

[0076] [Table 3]

[0077] [Table 4]

[0078] As can be seen from Tables 3 and 4, various improvements were confirmed in the tire evaluation and transponder evaluation for Examples 14 to 31. On the other hand, for Comparative Example 11, the position of the transponder in the tire radial direction was outside the range specified by the present invention, and therefore the communication performance of the transponder deteriorated. [Explanation of symbols]

[0079] 1 Tread section 2 Sidewall 3 Bead section 4 carcass layers 4A Main body 4B Winding section 5 bead core 6 Bead filler 7 Belt Layer 9 Inner liner layer 20 Transponder CL Tire centerline P1~P3 position

Claims

1. A pneumatic tire comprising a tread portion extending in the tire circumferential direction 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 radially inward of the sidewall portions, wherein a bead filler is disposed on the outer periphery of a bead core of each bead portion, at least one carcass layer is mounted between the pair of bead portions, a plurality of belt layers are disposed on the outer periphery of the carcass layer in the tread portion, and an inner liner layer is disposed adjacent to the carcass layer in the sidewall portions and along the carcass layer, a transponder extending along the tire circumferential direction is embedded between a position 15 mm radially outward from the upper end of the bead core and a position 5 mm radially inward from the end of the belt layer, the amount of silicon in the release agent detected by fluorescent X-ray analysis at least on the tire inner surface corresponding to the embedded position of the transponder is 0.1% by weight to 10.0% by weight, and the release agent does not contain carbon.

2. A pneumatic tire comprising a tread portion extending in the tire circumferential direction 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 radially inward of the sidewall portions, wherein a bead filler is disposed on the outer periphery of a bead core of each bead portion, at least one carcass layer is mounted between the pair of bead portions, a plurality of belt layers are disposed on the outer periphery of the carcass layer in the tread portion, and an inner liner layer is disposed adjacent to the carcass layer in the sidewall portions and along the carcass layer, a transponder extending along the tire circumferential direction is embedded between a position 15 mm radially outward from the upper end of the bead core and a position 5 mm radially inward from the end of the belt layer, the thickness of a release agent detected with an electron microscope at least on the tire inner surface corresponding to the embedded position of the transponder is 0.1 μm to 100 μm, and the release agent does not contain carbon.

3. 3. The pneumatic tire according to claim 1, wherein 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.

4. The pneumatic tire according to any one of claims 1 to 3, characterized in that the transponder is disposed between the carcass layer and a rubber layer disposed outside the carcass layer in the sidewall portion so as to abut against the rubber layer.

5. 5. The pneumatic tire according to claim 4, wherein the distance between the cross-sectional center of the transponder and the outer surface of the tire is 2 mm or more.

6. The pneumatic tire according to any one of claims 1 to 3, characterized in that the pneumatic tire has an inner liner layer disposed on the inner surface of the tire along the carcass layer, and the transponder is disposed between the carcass layer and the inner liner layer.

7. 7. The pneumatic tire according to claim 6, wherein the distance between the center of the cross section of the transponder and the inner surface of the tire is 1 mm or more.

8. The pneumatic tire according to any one of claims 1 to 7, characterized in that the transponder is disposed between a position 5 mm radially outward from an upper end of the bead filler and a position 5 mm radially inward from an end of the belt layer.

9. The pneumatic tire according to any one of claims 1 to 8, wherein the transponder is covered with a covering layer, and the covering layer has a relative dielectric constant of 7 or less.

10. The pneumatic tire according to any one of claims 1 to 9, wherein the transponder is covered with a covering layer, and the covering layer has a thickness of 0.5 mm to 3.0 mm.

11. 11. The pneumatic tire according to claim 1, wherein the transponder has an IC board for storing data and an antenna for transmitting and receiving data, and the antenna is spiral-shaped.

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