RFID tag for rubber product, rubber product, tire, and method for manufacturing RFID tag for rubber product

Abstract

To provide a small, mass-producible, and durable RFID tag for a rubber product, the rubber product, a tire, and a method for manufacturing the RFID tag for the rubber product.SOLUTION: An RFID tag 1 for a rubber product includes a sheet-like conductor portion 10, an RF chip 20, and a sheet-like rubber cover 40. The RF chip is electrically connected to the conductor portion to form a resonant circuit 50. The conductor portion and the RF chip are covered with the cover, and rubber of the cover contains carbon black, and a dielectric constant of the cover is higher than that of the rubber product to which the RFID tag for the rubber product is attached. When the RFID tag is attached to or embedded in a tire, influence of carbon black contained in the tire on the RFID tag can be suppressed, and communication can be stably performed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a small-sized RFID tag for rubber products that is suitable for mass production and has excellent durability, and to a method for manufacturing a rubber product, a tire, and an RFID tag for a rubber product. [Background technology]

[0002] The RFID tags used in RFID (Radio Frequency Identification) systems contain an antenna and an RF chip. The antenna receives the carrier wave transmitted from the reader / writer's antenna, and the identification data recorded on the RF chip is transmitted on a reflected wave back to the reader / writer, enabling contactless communication. By attaching or embedding RFID tags in the tires of vehicles such as automobiles, it is possible to manage the tire's unique information and the tire's history of manufacture, distribution, maintenance, etc. Of course, RFID tags can also be attached to or embedded in rubber products other than tires to help manage those products.

[0003] The RFID tag-embedded tire of Patent Document 1 has a first antenna connected to an IC chip and a second antenna electromagnetically coupled to the first antenna, and discloses a technology for electromagnetically coupling the second antenna to a conductive carcass ply cord. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-132291 Summary of the Invention [Problem to be solved by the invention]

[0005] When attaching RFID tags to tires, there are problems such as the risk of the RFID tag being damaged by deformation of the tire while in motion, and the problem of the free electrons in the carbon black contained in the tire transferring charge from negative to positive when exposed to radio waves, which causes current to flow from positive to negative, resulting in changes in impedance and dielectric constant. In Patent Document 1, the first antenna and the second antenna are electromagnetically coupled, and since the signal source impedance of the second antenna is high, there is a problem that it is susceptible to changes in impedance and relative dielectric constant due to the influence of carbon black. In addition, since the second antenna has a pair of extensions extending in the left-right direction from the electromagnetic field coupling portion, when the tire deforms, the left and right extensions are pulled in the left-right direction around the electromagnetic field coupling portion, which may cause damage.

[0006] In addition, RFID tags using conventional half-wave dipole antennas have the problem of being large in size, and even if a meander line antenna, which is made smaller by folding the antenna elements, is used, it is difficult to determine the effective meander length due to the influence of carbon black. Such problems can also occur when RFID tags are used in rubber products other than tires, particularly rubber products that contain materials such as carbon black that affect the communication performance of RFID tags.

[0007] In consideration of these problems, the present invention aims to provide a small-sized RFID tag for rubber products that is suitable for mass production and has excellent durability, and a method for manufacturing a rubber product, a tire, and an RFID tag for rubber products. [Means for solving the problem]

[0008] The RFID tag for rubber products of the present invention comprises a sheet-like conductor portion, an RF chip, and a sheet-like rubber cover, the RF chip being electrically connected to the conductor portion to form a resonant circuit, the conductor portion and the RF chip being covered by the cover, the rubber of the cover containing carbon black, and the relative dielectric constant of the cover being higher than the relative dielectric constant of the rubber product to which the RFID tag for rubber products is attached. The RF chip is also characterized by comprising a base on which the RF chip is placed, and the RF chip is electrically connected to the conductor portion while placed on the base. The conductor portion may also have a through hole. The present invention is also characterized by including a reinforcing layer. The reinforcing layer may also have through holes. The reinforcing layer is preferably a layer made of fiber. The reinforcing layer is made of twisted fibers having a fineness of 200 to 6000 dtex, and is characterized in that the reinforcing layer is rubber-bonded and is disposed on one or both sides of the conductor portion. The cover is characterized in that the amount of carbon black per 100 parts by mass of the rubber component is 51 to 70 parts by mass. The rubber of the cover is raw rubber before vulcanization. The rubber of the cover is a vulcanized rubber. The rubber product to be attached is a tire. The rubber product of the present invention is characterized by including the above-mentioned RFID tag for rubber products. The tire of the present invention is characterized by including the above-mentioned RFID tag for rubber products. The method for manufacturing an RFID tag for rubber products of the present invention uses a sheet-shaped conductor, an RF chip, and a sheet-shaped unvulcanized rubber cover, wherein carbon black is compounded into the rubber of the cover, and the relative dielectric constant of the cover is higher than the relative dielectric constant of the rubber product to which the RFID tag for rubber products is attached, and is characterized by comprising the steps of forming a resonant circuit by electrically connecting the RF chip to the conductor, covering the conductor and the RF chip with the cover, and vulcanizing the cover. [Effects of the Invention]

[0009] The dielectric constant of the cover is made higher than the dielectric constant of the rubber product to which the RFID tag for rubber products is attached. This reduces the effect of carbon black contained in the rubber product on the RFID tag when the RFID tag is attached to or embedded in the rubber product, ensuring stable communication. Furthermore, the RFID tag can capture an electric field by utilizing the free electrons of the carbon black contained in the rubber cover and the rubber product itself, such as a tire, to which the RFID tag is attached. In other words, since the rubber product itself, such as a tire, is used as an antenna, an RFID tag can be obtained that is small, easy to mass-produce, and durable compared to conventional RFID tags that use a dipole antenna or the like. If the rubber for the cover is raw rubber before vulcanization, an RFID tag can be embedded inside the rubber product such as a tire during its manufacturing process, and the rubber product and RFID tag can be integrated by vulcanizing it. When the rubber for the cover is vulcanized rubber, the RFID tag can be easily attached to a rubber product such as a ready-made tire. By sandwiching a reinforcing layer, the strength and durability of the RFID tag can be increased. By providing through holes in the conductor or reinforcing layer, the molten rubber passes through the holes during vulcanization, and after cooling, the conductor and base are fixed by the rubber, resulting in an RFID tag with excellent durability. [Brief explanation of the drawings]

[0010] [Figure 1] (a) is a plan view showing the components of an RFID tag for rubber products; (b) is a plan view showing the RFID tag for rubber products with the upper cover removed; and (c) is a longitudinal cross-sectional view showing the components of an RFID tag for rubber products. [Figure 2] FIG. 10 is a plan view showing components of a modified example of an RFID tag for rubber products. [Figure 3] 1A and 1B are plan views showing components of a modified example of an RFID tag for rubber products; [Figure 4] FIG. 1A is a plan view of a base, and FIG. 1B is a plan view showing a modified example of the base. [Figure 5] Equivalent circuit diagram of RFID tag for rubber products [Figure 6] 10A to 10E are plan views showing modified examples of the notch portion; [Figure 7] Cross-sectional diagrams showing RFID tags attached to the inner liner and sidewall of a tire, and embedded in the tire. [Figure 8] A graph showing the radio wave frequency (horizontal axis) and reading distance (vertical axis) when RFID tags for rubber products are attached to the inner liner and sidewall of a passenger car tire. [Figure 9] A graph showing the radio wave frequency (horizontal axis) and reading distance (vertical axis) when RFID tags for rubber products are attached to the sidewall and inner liner of truck tires. [Figure 10] A graph showing the radio wave frequency (horizontal axis) and reading distance (vertical axis) when RFID tags for rubber products are attached to the sidewall and inner liner of a tractor tire. [Figure 11] FIG. 10 is a plan view showing an RFID tag for rubber products according to a second embodiment; [Figure 12] 10A and 10B are a plan view and a longitudinal sectional view showing components of an RFID tag for rubber products according to a third embodiment of the present invention; [Figure 13] Equivalent circuit diagram of the RFID tag for rubber products according to the third embodiment [Figure 14] 1A to 1E are longitudinal cross-sectional views showing modified examples of RFID tags for rubber products. [Figure 15]10A and 10B are a plan view and a longitudinal sectional view showing components of an RFID tag for rubber products according to a fourth embodiment of the present invention; [Figure 16] 10A and 10B are a plan view and a longitudinal sectional view showing components of an RFID tag for rubber products according to a fifth embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0011] [First embodiment] A first embodiment of an RFID tag for rubber products according to the present invention will be described with reference to the drawings. 1, the RFID tag 1 for rubber products includes a conductor portion 10, an RF chip 20, a base 30, and a rubber cover 40. In the following description, the RFID tag 1 for rubber products may be simply referred to as the "RFID tag 1." As will be described later, the base 30 is not necessarily required for the RFID tag for rubber products of the present invention.

[0012] The conductor portion 10 functions as an antenna that receives a carrier wave from a reader / writer and returns a reflected wave to the reader / writer. The conductor 10 is a thin mesh sheet with many through holes 10a. In this embodiment, a cutout 11 is provided in a part of the conductor 10. The material of the conductor 10 may be a metal such as copper wire, iron wire, or brass wire.

[0013] As shown in Fig. 1, a fiber layer 13 may be laminated on the conductor 10 as a reinforcing layer 13, or as shown in Fig. 2, the conductor 10 may be a woven or knitted fabric 14 made of metal threads (fibers made of metals such as copper wire, iron wire, or brass wire) and fibers. The fibers constituting the fiber layer 13 and the woven or knitted fabric 14 are preferably polyester fibers primarily composed of PET, PEN, or polyarylate; polyamides primarily composed of nylon 6, nylon 66, nylon 46, nylon 56, nylon 410, or the like; para-aramid or copolymers containing a third component thereof; wholly aromatic polyamides primarily composed of meta-aramid, or the like; rayon such as viscose rayon, Tencel, or lyocell; polyvinyl alcohol; cotton; carbon fiber; steel; copper wire; or other inorganic fibers. Considering the balance of strength, durability, cost, and other factors, PET, nylon 6, and nylon 66 are more preferred. From the viewpoint of the effects of the present invention, when fibers are used for the conductor portion 10 and the reinforcing layer 13, the fineness is preferably 200 to 6000 dtex (g / 10000 m), and the strength is preferably 4 cN / dtex or more. The fibers preferably have heat resistance that allows them to withstand the rubber vulcanization molding temperature, and the melting point of the fiber material made of a thermoplastic polymer is preferably 200°C or more. The number of twists of the fibers is preferably 50 to 600 times / m, and either a single twist or a double twist may be used. The fiber layer 13 and the woven / knitted fabric 14 may be in the form of a blind, biaxial woven fabric, multiaxial woven fabric, warp knitting, weft knitting, or the like, and are not particularly limited, but a thickness of 0.1 to 1.0 mm is preferred. To improve the adhesive strength between the fibers of the fiber layer 13 and the woven / knitted fabric 14 and the rubber cover 40 and to impart durability to the RFID tag 1 for rubber products, it is preferred to subject the fibers to a known adhesive treatment such as RFL treatment, and in the case of RFL adhesive treatment, the adhesive deposition amount is preferably 2 to 20%. If necessary, an adhesive treatment that combines a primer treatment and an RFL adhesive treatment may be performed. By using fibers, the strength of the conductor portion 10 can be increased, and the gaps between the fibers can be used as through holes 13a and 14a. If the strength of the conductor 10 can be ensured, the conductor 10 may be formed only from a thin metal plate 15 as shown in Fig. 3(a) without the reinforcing layer 13, in which case gaps naturally occurring in the thin metal plate 15 may be used as through holes. Also, as shown in Fig. 3(b), the conductor 10 may be formed only from a mesh-like thin metal plate 16 without the reinforcing layer 13. Although a commercially available product can be used as the RF chip 20, it is preferable to use one that can withstand vulcanization temperatures (for example, about 120° C.).

[0014] The base 30 is a member on which the RF chip 20 is mounted. As the base 30, for example, as shown in FIG. 4(a), a copper foil 32 may be attached to the surface of a polyimide or liquid crystal polymer as a base film 31, or an epoxy resin containing reinforcing fibers such as glass fiber may be disposed on the surface of the copper foil 32. Alternatively, the base 30 may be rectangular as shown in FIG. 4(b). It is preferable that the base 30 has a through hole 33. Both ends of the RF chip 20 are connected to the copper foil 32, and the RF chip 20 is bridged over the notch 11 so as to be electrically connected to the conductor 10 while placed on the base 30. By electrically connecting the RF chip 20 to the conductor 10 while placed on the base 30 in this manner, a resonant circuit 50 is formed.

[0015] The rubber cover 40 is in the form of a sheet, and can be used in the form of raw rubber before vulcanization or in the form of rubber after vulcanization. The general rubber manufacturing process includes a kneading process in which natural rubber and additives are kneaded to obtain a kneaded mixture, a raw rubber molding process in which raw rubber is molded from the kneaded mixture, and a vulcanization process in which raw rubber is vulcanized. In this specification, the product obtained in the raw rubber molding process (product before the vulcanization process) is called "raw rubber." Additives used in the kneading step include at least a vulcanizing agent such as sulfur, a vulcanization accelerator, and carbon black, but also include, for example, reinforcing fillers such as silica, calcium carbonate, alumina, clay, and talc, silane coupling agents, zinc oxide, stearic acid, processing aids, various antioxidants, softeners such as oil, and wax. The cover 40 is manufactured from a thin sheet of raw rubber in a raw rubber molding process. Alternatively, the cover 40 made from raw rubber may be vulcanized in a vulcanization process to manufacture the cover 40 made from vulcanized rubber. The RFID tag 1 for rubber products is then completed by sandwiching the conductor 10, base 30, and RF chip 20 between two rubber covers 40 from above and below.

[0016] Carbon black is compounded into the rubber of the cover 40, making the relative dielectric constant of the cover 40 higher than the relative dielectric constant of the rubber product to which the RFID tag 1 for rubber products is attached. For example, assuming that the RFID tag 1 is attached to or embedded in the tires of a typical vehicle (passenger car, truck, or bus), the carbon black content of the tires of a typical vehicle is estimated to be approximately 30 to 60 parts by mass per 100 parts by mass of rubber components. Regarding the carbon black compounded into the rubber that forms the material for the cover 40, if the carbon black content per 100 parts by mass of the rubber components is greater than 60 parts by mass, the relative dielectric constant of the cover 40 will be higher than that of a typical tire. Therefore, when the RFID tag 1 is attached to or embedded in the tires of a typical vehicle, the effects of the carbon black contained in the tires on the RFID tag 1 (for example, changes in inductance and frequency) can be suppressed, ensuring stable communication. If the dielectric constant of cover 40 were lower than that of the rubber product to which rubber product RFID tag 1 is attached, the inductance of inductor pattern 51 that constitutes resonant circuit 50 (described later) would change, causing a change in resonant frequency f0 and making communication difficult. Thus, one of the features of the present invention is that by making the dielectric constant of rubber cover 40 of RFID tag 1 higher than that of the tire, it is no longer necessary to adjust the inductance depending on the type of tire, and a highly versatile RFID tag 1 can be obtained. Considering that the carbon black content varies depending on the tire's application as described above, it is preferable that the carbon black content be approximately 51 to 70 parts by mass per 100 parts by mass of the rubber component of the cover 40. The inventors of the present application have confirmed through experiments that when the RFID tag 1 is attached to a truck tire, good communication conditions can be ensured when the carbon black content is 51, 60, or 70 parts by mass per 100 parts by mass of the rubber component of the cover 40, and that the best communication band and communication distance can be ensured when the carbon black content is 60 parts by mass. From the above viewpoints, in the present invention, the carbon black content of the cover 40 is preferably at least 1 part by mass, more preferably at least 5 parts by mass, even more preferably at least 10 parts by mass, and particularly preferably at least 15 parts by mass, more ... Furthermore, by providing the RFID tag 1 for rubber products with rubber covers 40 on the top and bottom, even if the rubber product to which the RFID tag 1 for rubber products is attached is deformed, it is possible to prevent the components that make up the RFID tag 1 for rubber products from being damaged or the components from becoming misaligned relative to each other, and it is also possible to make the RFID tag 1 for rubber products waterproof and dustproof.

[0017] The RF chip 20 operates based on the radio waves received by the conductor 10. Specifically, the RF chip 20 rectifies a portion of the carrier wave transmitted from the reader / writer to generate the power supply voltage required for operation. The RF chip 20 then uses the generated power supply voltage to operate the control logic circuit within the RF chip 20 and the nonvolatile memory that stores product-specific information, and to operate the communication circuit for transmitting and receiving data to and from the reader / writer.

[0018] As described above, the resonant circuit 50 is formed in the RFID tag 1 for rubber products so as to resonate in the frequency band of the radio waves to be received. This resonant circuit 50 is composed of an inductor pattern 51, a capacitor 52, and an RF chip 20, as shown in the equivalent circuit diagram of FIG. As shown in FIG. 6, the inductor pattern 51 is composed of the RF chip 20 bridging the notch 11 and the end face of the notch 11 . The capacitor 52 is configured with the equivalent capacitance of the RF chip 20. Some RF chips 20 include a capacitor inside, and the RF chip 20 has stray capacitance. For this reason, it is preferable to take into consideration the equivalent capacitance inside the RF chip 20 when setting the resonant frequency of the resonant circuit 50. In other words, it is preferable that the resonant circuit 50 has a resonant frequency that is set in consideration of the inductance of the inductor pattern 51, the equivalent capacitance inside the RF chip 20, and the relative dielectric constant of raw rubber.

[0019] The resonant frequency f0 [Hz] of this series resonant circuit 50 is given by equation (1). The value of the resonant frequency f0 is preferably set to be approximately the center value of the frequency bandwidth of the multiple radio waves transmitted from the reader.

number

[0020] By taking into account the equivalent capacitance inside the RF chip 20 in this way, the resonant frequency f0 of the resonant circuit 50 can be set accurately within the frequency band of the radio waves. As a result, the reading performance of the RFID tag 1 can be improved. In addition, the power supply voltage generated by the RF chip 20 can be increased. 6(a) and 6(b), by adjusting the positions of the RF chip 20 and the base 30 relative to the cutout 11, a variable inductor pattern 51 is formed, and the resonant frequency f0 can be adjusted by adjusting L. In addition, the shape of the cutout 11 can be changed as appropriate, as shown in FIGS. 6(c) to 6(e).

[0021] Next, a method for manufacturing the RFID tag 1 for use in rubber products will be described. First, the RF chip 20 mounted on the base 30 is electrically connected to the conductor portion 10 to form the resonant circuit 50. Next, the conductor portion 10, the base 30 and the RF chip 20 are sandwiched between two sheet-like covers 40 made of unvulcanized raw rubber. Finally, the raw rubber is vulcanized. For example, the raw rubber can be vulcanized by sandwiching the conductor portion 10, the base 30, and the RF chip 20 between two covers 40 made of raw rubber from above and below, and then applying heat and pressure in a vulcanizer. As described above, by forming the conductor 10 in a mesh shape and providing the through holes 10a, and by providing the reinforcing layer 13 and the base 30 with the through holes 13a, 33, the rubber melted during vulcanization passes through the through holes 10a, 13a, 33, and after cooling, an anchoring effect is obtained in which the conductor 10 and the base 30 are fixed by the rubber. This makes it possible to obtain an RFID tag 1 for rubber products that is highly durable. The conductor portion 10, the base 30 and the RF chip 20 may be sandwiched between two sheet-like covers 40 made of vulcanized rubber, and the covers 40 may be bonded together.

[0022] FIG. 7 shows the RFID tag 1 attached to the inner liner and sidewall of a tire T as an example of a rubber product, and embedded in the tire T. Figure 8 is a graph showing the radio wave frequency (horizontal axis) and reading distance (vertical axis) when an RFID tag 1 for rubber products is attached to the inner liner and sidewall of a passenger car tire. It can be seen that one RFID tag 1 is compatible with two frequency bands: the low frequency side (around 860 MHz) used mainly in Europe (Eu) and the high frequency side (around 920 MHz) used mainly in Japan (Jp). It can also be seen that it is possible to read even if there is a bead wire inside the tire.

[0023] Figure 9 is a graph showing the radio wave frequency (horizontal axis) and reading distance (vertical axis) when RFID tag 1 for rubber products is attached to the sidewall and inner liner of a truck tire. When attached to the sidewall, the reading distance is lower on the high-frequency side used in Japan, but this does not pose a practical problem, and it can be seen that one RFID tag can be used for two different frequency bands. Figure 10 is a graph showing the radio wave frequency (horizontal axis) and reading distance (vertical axis) when RFID tag 1 for rubber products is attached to the sidewall and inner liner of a tractor tire. It shows that one RFID tag can be used for two different frequency bands.

[0024] The RFID tag 1 has a structure that utilizes the free electrons of carbon black contained in the rubber cover 40 and the rubber product itself, such as a tire, to which the RFID tag 1 is attached, to capture an electric field into the RFID tag 1. In other words, the RFID tag is characterized by utilizing the rubber product itself, such as a tire, as an antenna. Furthermore, when the RFID tag 1 uses raw rubber before vulcanization, the RFID tag 1 can be embedded inside the raw tire during tire manufacturing and then vulcanized to integrate the tire and the RFID tag 1.

[0025] [Second embodiment] Next, a second embodiment of the present invention will be described. The same components as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted. As shown in FIG. 11, the RFID tag of this embodiment is characterized in that the conductor portion 60 does not have the notch portion 11.

[0026] Specifically, the base 30 has an opening 34 in the center and a roughly U-shaped slit 35 in part, with the RF chip 20 spanning the slit 35. The opening 34 of the base 30 and the part including the RF chip 20 are separated from the conductor part 60, and only a part of the base 30 is connected to the conductor part 60. In this structure, the inductor pattern 51 is formed by the RF chip 20 and the end face portion of the opening 34, the capacitor 52 is formed by the equivalent capacitance of the RF chip 20, and the RF chip 20 is electrically connected to the conductor portion 60 while placed on the base 30 to form the resonant circuit 50.

[0027] [Third embodiment] Next, a third embodiment of the present invention will be described. The same components as those in the above-described embodiments will be designated by the same reference numerals and the description thereof will be omitted. As shown in FIG. 12, the RFID tag of this embodiment is characterized in that the RF chip 20 is electrically connected directly to the conductor portion 10 without the base 30 being interposed therebetween. The conductor 10 is formed from a thin plate of metal such as aluminum, and has a notch 11 in one part thereof. Both ends of the RF chip 20 are bridged over the notch 11 so as to be electrically connected to the conductor 10. A resonant circuit is formed by electrically connecting the RF chip 20 to the conductor 10. An equivalent circuit diagram of the resonant circuit 53 is shown in FIG. 13.

[0028] As shown in Figure 12(b), the front and back surfaces of the conductor portion 10 are sealed with an insulating layer 70 made of insulating resin. Epoxy resin, polyimide, acrylic resin, polyester resin, silicone resin, fluororesin, etc. can be used as the insulating layer 70. In particular, it is preferable to use PET (polyethylene terephthalate), which is a type of polyester resin. The through-holes 17 are formed by punching the conductor 10 while the front and rear surfaces of the conductor 10 are sealed with the insulating layer 70 . The front and rear surfaces of the conductor portion 10 sealed with the insulating layer 70 are covered with a fiber layer 13 as a reinforcing layer 13, and are further covered with a rubber cover 40.

[0029] As described above, the conductor 10 and the insulating layer 70 have through holes 17, and the fiber layer 13 also has through holes 13a, so the rubber of the cover 40 that melts during vulcanization passes through the through holes 17, 13a, and after cooling, the anchor effect of the rubber fixes the conductor 10 and the reinforcing layer 13 integrally with the rubber cover 40. This makes it possible to obtain an RFID tag for rubber products that is highly durable.

[0030] In this embodiment, two reinforcing layers 13 are provided, but it is also possible to provide only one reinforcing layer 13 as shown in Figure 14(a), or even to provide no reinforcing layer 13 as shown in Figure 14(b). Furthermore, as shown in FIG. 14(c), the conductor portion 10 and the reinforcing layer 13 may not have through holes 17, 13a. Furthermore, as shown in Figure 14(d), one rubber cover 40 may be bent to sandwich the conductor portion 10 and the RF chip 20 from above and below, or as shown in Figure 14(e), one reinforcing layer 13 may be bent to sandwich the conductor portion 10 and the RF chip 20 from above and below.

[0031] [Fourth embodiment] Next, a fourth embodiment of the present invention will be described. The same components as those in the above-described embodiments will be designated by the same reference numerals and the description thereof will be omitted. As shown in FIG. 15, the RFID tag of this embodiment is characterized in that the conductor portion 10 and the RF chip 20 are covered with a single rubber cover 40, as compared to the RFID tag of the third embodiment shown in FIG. In this configuration, the side without the cover 40 (the lower side in FIG. 15(b)) may be attached to a rubber product such as a tire.

[0032] [Fifth embodiment] Next, a fifth embodiment of the present invention will be described. The same components as those in the above-described embodiments will be designated by the same reference numerals and the description thereof will be omitted. As shown in FIG. 16, the RFID tag of this embodiment is characterized in that the RFID chip 20 is electrically connected to the conductor portion 10 via the base 30, as compared with the RFID tag shown in FIG. By using the configuration of this embodiment, an RFID tag for rubber products with the highest durability can be obtained. [Example]

[0033] In the first embodiment of the present invention, the RFID tag 1 for rubber products shown in FIG. 1 was fabricated using a copper mesh sheet (0.5 mm copper wire diameter, 1 mm mesh grid spacing) as the conductor 10, an Impinj. Inc. tag chip (product name: M730) as the RF chip 20, and a rectangular base as shown in FIG. 4(b) with a cured epoxy resin blended with glass fiber placed on the surface of copper foil as the base 30. The reinforcing layer 13 was a mesh fabric made of nylon 6 fibers with a thickness of 470 dtex and 14 filaments and treated with an RFL adhesive. The rubber cover 40 was fabricated using a rubber composition containing natural rubber and carbon black (carbon black contents of 30 parts by mass, 40 parts by mass, 51 parts by mass, 60 parts by mass, and 70 parts by mass). The results of attaching this RFID tag 1 for rubber products to a tire containing 38 parts by mass of carbon black are shown in the table below. The materials and numbers of the components constituting the RFID tag 1 for rubber products shown in the first embodiment are not limited to those shown here. [Table 1]

[0034] The radio wave readable distance and impedance disturbance were measured by the following method. An RFID tag 1 was attached to the outside of the tire sidewall, and a handheld RFID reader (Toshiba Tec Corporation, product name: UF-3000-HL-S) was used to measure the horizontal radio wave readable distance from the RFID tag 1 at a frequency of 920.4 MHz and a radio wave output of 1 W. In this way, it was confirmed that the RFID tag 1 for rubber products according to the embodiment of the present invention has excellent radio wave readability over long distances due to resonance, and has a radio wave readable distance of preferably 6 m or more, and further 8 m or more, and that impedance disturbance is also suppressed. [Example]

[0035] Regarding the third embodiment of the present invention, a biaxially stretched polyethylene terephthalate film (film thickness: 180 μm) with aluminum vapor-deposited conductor portion 10 was prepared from first embodiment C in Table 1 as the RFID tag 1 for rubber products shown in FIG. 3. Also, a tag in which an RFID was directly attached to the conductor portion without using a base 30 was prepared, and designated as third embodiment E. Regarding the fifth embodiment of the present invention, a tag in which a 50 μm-thick stainless steel plate was used as the conductor portion 10 from the first embodiment C described above was prepared, and designated as fifth embodiment F. When attached to a tire containing 38 parts by mass of carbon black, the radio wave readable distance was 12 m, the same as in First Embodiment C. The RFID tags 1 for rubber products of Third Embodiment E and F of F were each gripped with a chuck at the top and bottom longitudinal ends, and stretched by 5% using a Shimadzu EHF-UV050k2 chuck, and then returned to the original chuck position. This cycle was repeated 1.6 million times at a frequency of 8.2 Hz. Third Embodiment E was no longer able to read radio waves from a distance of 12 m, but Fifth Embodiment F was able to read radio waves from a distance of 12 m. [Industrial Applicability]

[0036] The present invention relates to a small-sized RFID tag for rubber products that is suitable for mass production and has excellent durability, and to a method for manufacturing a rubber product, a tire, and an RFID tag for a rubber product, and has industrial applicability. [Explanation of symbols]

[0037] T Tire 1. RFID tags for rubber products 10 Conductor 10a through hole 11 Notch 13 Reinforcement layer (fiber layer) 13a Through hole 14 Woven and knitted fabrics 15 Thin Metal Plates 16 Mesh-like metal sheet 17 through holes 20 RF chips 30 base 31 Base film 32 Copper foil 33 Through Hole 34 Aperture 35 Slit 40 Rubber Cover 50 resonant circuit 51 Inductor pattern 52 Capacitor 53 Resonant circuit 60 Conductor 70 insulating layer

Claims

1. It is equipped with a sheet-shaped conductor, an RF chip, and a sheet-shaped rubber cover. the RF chip is electrically connected to the conductor portion to form a resonant circuit, the conductor portion and the RF chip are covered with the cover, An RFID tag for rubber products, characterized in that carbon black is compounded in the rubber of the cover, and the relative dielectric constant of the cover is higher than the relative dielectric constant of the rubber product to which the RFID tag for rubber products is attached.

2. a base on which the RF chip is mounted; 2. The RFID tag for rubber products according to claim 1, wherein the RF chip is electrically connected to the conductor portion while being placed on the base.

3. 3. The RFID tag for rubber products according to claim 1, wherein the conductor portion has a through hole.

4. 3. The RFID tag for rubber products according to claim 1, further comprising a reinforcing layer.

5. The RFID tag for rubber products according to claim 4, characterized in that the reinforcing layer has a through hole.

6. The RFID tag for rubber products according to claim 4, wherein the reinforcing layer is a layer made of fiber.

7. The RFID tag for rubber products according to claim 6, characterized in that the reinforcing layer is made of twisted fibers with a fineness of 200 to 6000 dtex, and the reinforcing layer is rubber-bonded and is disposed on one or both sides of the conductor portion.

8. 3. The RFID tag for rubber products according to claim 1, wherein the content of carbon black in the cover is 51 to 70 parts by mass per 100 parts by mass of the rubber component.

9. 3. The RFID tag for rubber products according to claim 1, wherein the rubber of the cover is raw rubber before vulcanization.

10. 3. The RFID tag for rubber products according to claim 1, wherein the rubber of the cover is vulcanized rubber.

11. 3. The RFID tag for rubber products according to claim 1, wherein the rubber product to which the tag is attached is a tire.

12. A rubber product comprising the RFID tag for rubber products according to claim 1 or 2.

13. A tire comprising the RFID tag for rubber products according to claim 1 or 2.

14. A tire comprising the RFID tag for rubber products according to claim 6.

15. It uses a sheet-shaped conductor, an RF chip, and a sheet-shaped unvulcanized rubber cover. the cover rubber contains carbon black, and the cover has a higher dielectric constant than the rubber product to which the RFID tag for rubber products is attached; forming a resonant circuit by electrically connecting the RF chip to the conductor; covering the conductor portion and the RF chip with the cover; and vulcanizing the cover.

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