Rubber lamination alternative coating composition for tire-embedded RFID tags and RFID tags using the same

Abstract

The present invention relates to a coating composition for an RFID tag embedded in a tire. A coating composition according to one embodiment of the present invention comprises a base rubber and a pigment additive, and the pigment additive may be composed of one or more selected from carbon black, calcium carbonate (CaCO3), talc, clay, barium sulfate (BaSO4), and fumed silica. In addition, an RFID tag according to one embodiment of the present invention may be configured to form a coating layer with the coating composition using a coating application device. According to one embodiment of the present invention, by performing the protection and bonding of an RFID tag embedded in a tire using a primer and coating instead of lamination (topping), the generation of air (bubbles) can be suppressed, thereby minimizing the occurrence of defects. In addition, according to one embodiment of the present invention, the coating thickness can be precisely controlled by a coating application device, and accordingly, when changing tire size, recipe parameterization becomes easy, which enables quality stabilization and tolerance management.

Description

Technology Field

[0001] The present invention relates to a coating composition for RFID tags for tire embedding, and more specifically, to a coating composition that replaces the rubber lamination (topping) previously used for RFID tags by applying a coating agent (coating composition) to the RFID tag to impart a rubber topping effect, thereby enabling tire embedding after coating without rubber lamination (topping). Background Technology

[0002] Recently, there has been a growing trend of embedding RFID tags in automotive tires to link individual identification with production, logistics, maintenance, and recycling history. To achieve this, a manufacturing process has typically been adopted in which tag modules are placed inside rubber laminates, such as the sidewall, and the tag surface is covered with rubber lamination (topping) before being integrated through a vulcanization process.

[0003] While conventional lamination (topping) processes are useful for protecting tags, reducing exposure to external forces and chemicals, and ensuring mechanical bonding with the rubber matrix, they continuously expose the following structural limitations in actual production environments.

[0004] For example, conventional lamination (topping) processes have problems with air entrainment and the formation of air pockets. There are frequent shape and curvature conditions where air is prone to remaining at the interface between the tag capsule and the green rubber sheet, and it is often difficult to completely eliminate this through stitching and calendering alone.

[0005] This residual air expands during vulcanization, causing micropores and delamination. It also acts as a crack initiation point under repeated bending, which tends to lead to reduced durability and reliability. Furthermore, interfacial discontinuities and local thickness variations are accompanied by RF detuning and increased losses, which in some cases directly result in a decrease in read distance and angle uniformity.

[0006] Furthermore, conventional lamination (topping) processes face the problem of increased equipment investment and maintenance burdens. It is necessary to secure auxiliary equipment such as dedicated lamination lines, rollers, heating, pressure regulation, and degassing, making increases in initial investment costs and periodic maintenance expenses inevitable. Additionally, the process is sensitive to variations in composition, viscosity, and temperature, which poses a problem in that maintaining operating conditions requires significant management resources.

[0007] Furthermore, conventional lamination (topping) processes present challenges regarding installation space and line integration. Adding a separate lamination unit to an existing tire building line requires layout changes and workflow reconfiguration, and securing space within a limited workspace is difficult. Additionally, the increase in process steps leads to longer takt times, and there are issues such as the accumulation of quality risks—including contamination, moisture absorption, and surface energy degradation—during waiting and transfer between processes.

[0008] Furthermore, conventional lamination (topping) processes present conflicting issues in terms of materials and RF. Conventional topping is primarily based on the lamination of rubber sheets, which limits the freedom of microprocessing and material design, such as wettability, interfacial energy control, and optimization of local dielectric properties.

[0009] As the above problems are continuously being raised in industrial settings, there is a need for a technical attempt to directly form a dispensing special coating agent consisting of a primer layer and a top coating layer on the surface of an RFID tag, thereby reducing defects such as air bubbles, equipment investment, and space constraints associated with lamination (topping) at the root cause level, while simultaneously satisfying adhesion, flexibility, and RF performance. Prior art literature

[0010] Registered Patent Publication No. 10-2835030 (July 11, 2025) The problem to be solved

[0011] The present invention aims to solve the aforementioned problems. The objective of the present invention is to provide a coating composition for an RFID tag for tire embedding that can improve interfacial wettability and fundamentally prevent the generation of air (bubbles) by providing a special coating layer that can be directly applied to the surface of an RFID tag without relying on a lamination (topping) process.

[0012] In addition, the problem to be solved by the present invention is to provide a coating composition for an RFID tag for tire embedding that can secure strong adhesive co-vulcanization compatibility with the tire body rubber, maintain low dielectric and low loss characteristics suitable for UHF RFID tags to preserve and improve reading performance, and enable the integration of a dispensing-based coating process without separate lamination equipment, thereby reducing the burden of equipment, space, and cost. means of solving the problem

[0013] A coating composition according to one embodiment of the present invention for solving the above problems comprises a base rubber and a pigment additive, and the pigment additive may be composed of one or more selected from the group consisting of carbon black, calcium carbonate (CaCO3), talc, clay, barium sulfate (BaSO4), and fumed silica.

[0014] In addition, a coating composition according to one embodiment of the present invention may be configured such that the ratio of the base rubber and the pigment additive is 1:0.3 to 1:10.

[0015] An RFID tag according to one embodiment of the present invention comprises: a substrate; an RFID chip formed on the substrate; a primer layer applied on the substrate and the RFID chip; and a coating layer applied on the primer layer, wherein the coating layer may be composed of the coating composition.

[0016] An RFID tag according to one embodiment of the present invention may be configured such that the thickness of the coating layer is 0.3 mm to 1.5 mm.

[0017] An RFID tag according to one embodiment of the present invention may be formed such that the coating layer is formed so that the antenna bonded to the surface of the RFID tag is not completely visible.

[0018] An RFID tag according to one embodiment of the present invention may be configured to form a coating layer using the coating composition by using a coating application device. Effects of the invention

[0019] A coating composition for an RFID tag embedded in a tire according to one embodiment of the present invention can minimize defects by suppressing the generation of air (bubbles) by performing protection and bonding of the RFID tag embedded (embedded) in the tire using a primer and a coating instead of lamination (topping).

[0020] In addition, according to one embodiment of the present invention, the low volatility / low moisture design of the coating itself minimizes the source of vaporization during vulcanization, and accordingly, the rate of air pocket formation can be significantly reduced and an effect of inhibiting interfacial delamination can be secured.

[0021] In addition, according to one embodiment of the present invention, separate lamination-specific equipment, degassing rollers, heating units, etc. are unnecessary, and only an inline dispensing coating process needs to be added to the existing building line, thereby reducing equipment investment, maintenance costs, and line occupancy space, which has the effect of simplifying the manufacturing process and reducing costs.

[0022] In addition, according to one embodiment of the present invention, the occurrence of cracks due to repeated bending can be minimized by the chemical bonding of the primer and the low stiffness / stress relaxation characteristics of the coating layer, thereby improving interfacial adhesion and bending resistance at the coating agent interface.

[0023] In addition, according to one embodiment of the present invention, coating is made possible by minimizing the carbon black content that affects RF attenuation, and RF performance can be maintained or improved by offsetting the effect of RF attenuation.

[0024] In addition, according to one embodiment of the present invention, the coating thickness can be precisely controlled by a coating application device, and accordingly, when changing tire size, recipe parameterization becomes easy, which enables quality stabilization and tolerance management. Brief explanation of the drawing

[0025] FIG. 1 is a schematic diagram of an RFID tag according to one embodiment of the present invention. Specific details for implementing the invention

[0026] The description of the present invention is merely an example for structural or functional explanation, and therefore the scope of the present invention should not be interpreted as being limited by the examples described in the text. That is, since the examples may be modified in various ways and may take various forms, the scope of the present invention should be understood to include equivalents capable of realizing the technical concept.

[0027] Meanwhile, the meaning of the terms described in this invention should be understood as follows.

[0028] Terms such as "first," "second," etc., are intended to distinguish one component from another, and the scope of rights shall not be limited by these terms. For example, the first component may be named the second component, and similarly, the second component may be named the first component.

[0029] When it is stated that one component is "connected" to another component, it should be understood that while it may be directly connected to that other component, there may also be other components in between. Conversely, when it is stated that one component is "directly connected" to another component, it should be understood that there are no other components in between. Meanwhile, other expressions describing the relationships between components, such as "between" and "exactly between," or "adjacent to" and "directly adjacent to," should be interpreted in the same way.

[0030] A singular expression should be understood to include a plural expression unless the context clearly indicates otherwise, and terms such as "include" or "have" are intended to specify the existence of the implemented features, numbers, steps, actions, components, parts, or combinations thereof, and should be understood not to preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0031] In each step, identifiers (e.g., a, b, c, etc.) are used for convenience of explanation and do not describe the order of the steps; the steps may occur differently from the specified order unless a specific order is clearly indicated in the context. That is, the steps may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

[0032] Unless otherwise defined, all terms used herein have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having meanings consistent with the context of the relevant technology and should not be interpreted as having an ideal or overly formal meaning unless explicitly defined in this invention.

[0033] A coating composition for an RFID tag for tire embedding according to one embodiment of the present invention comprises a base rubber and a pigment additive, and the pigment additive may comprise one or more selected from the group consisting of carbon black, calcium carbonate (CaCO3), talc, clay, barium sulfate (BaSO4), silica, and fumed silica.

[0034] The above base rubber may be composed of one or more selected from natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), butyl rubber (IIR), and synthetic natural rubber (IR).

[0035] Natural rubber (NR) is based on cis-1,4-polyisoprene and has excellent tensile strength, fatigue durability, and fracture resistance.

[0036] Styrene-butadiene rubber (SBR) includes E-SBR (emulsion polymerization) and S-SBR (solution polymerization). S-SBR has a wide range of formulation optimization and features that are advantageous for tuning wet road grip and fuel efficiency performance.

[0037] Butadiene rubber (BR) has good high elasticity and low heat generation properties, making it useful for lowering rolling resistance and reducing wear.

[0038] Butyl rubber (IIR) is characterized by excellent gas barrier properties.

[0039] Synthetic natural rubber (IR) is a polyisoprene that artificially replicates physical properties similar to natural rubber (NR) and can be selected to ensure quality uniformity.

[0040] For example, based on 100 parts by weight of the base rubber, it may be composed of one or more selected from 40 to 60 parts by weight of natural rubber, 40 to 60 parts by weight of butadiene rubber, 30 to 50 parts by weight of styrene-butadiene rubber, 30 to 50 parts by weight of butyl rubber, and 10 to 30 parts by weight of synthetic natural rubber.

[0041] For reference, when RFID tags are embedded in a tire, they can be embedded in the sidewall portion of the tire. The tire sidewall is often composed of a combination of natural rubber (NR) and butadiene rubber (BR) and can be configured to be resistant to bending and fatigue, and to suppress ozone and cracking.

[0042] In the present invention, the pigment additive may be composed of one or more selected from carbon black, calcium carbonate (CaCO3), talc, clay, barium sulfate (BaSO4), and fumed silica.

[0043] Additionally, as needed, the pigment additive may be composed of one or more selected from carbon black, calcium carbonate (CaCO3), talc, clay, barium sulfate (BaSO4), fumed silica, hydrophobic fumed silica, silanized zeolite, and silica aerogel.

[0044] For example, based on 100 parts by weight of the base rubber, it may be composed of one or more selected from carbon black 1 to 30 parts by weight, calcium carbonate 1 to 10 parts by weight, talc 1 to 10 parts by weight, clay 1 to 5 parts by weight, barium sulfate 1 to 5 parts by weight, silica 1 to 5 parts by weight, hydrophobic fumed silica 0.1 to 3 parts by weight, silanized zeolite 0.1 to 3 parts by weight, and silica aerogel 0.1 to 3 parts by weight.

[0045] Carbon black is fine carbon particles obtained by the incomplete combustion or thermal decomposition of petroleum hydrocarbons (mainly heavy oil and tar), and has an aggregate structure in which spherical particles with a particle size of 10 to 100 nm are aggregated. For example, carbon black such as ISAF, HAF, FEF, GPF, and SRF can be used.

[0046] Carbon black has the characteristic of being able to significantly improve tensile strength, tear strength, and wear resistance by interacting with natural rubber and synthetic rubber molecules, and can suppress heat generation in tires by dispersing and releasing heat generated during driving.

[0047] Calcium carbonate (CaCO3) is a white inorganic powder that can be obtained from nature (limestone, marble, chalk) or manufactured through synthesis. It is chemically stable and has the characteristic of releasing CO2 and converting into CaO upon thermal decomposition.

[0048] In addition, calcium carbonate has the characteristic of being able to control viscosity and improve processing stability when incorporated into rubber.

[0049] Talc is a soft white to grayish-white inorganic mineral and is one of the softest minerals with a Mohs hardness of 1. Due to its plate-like crystal structure, talc can impart lubricity, smoothness, and heat resistance when used as a pigment additive. In other words, talc is characterized by low physical hardness and high lubricity.

[0050] In terms of chemical properties, it is chemically stable due to its resistance to acid-base reactions and does not decompose even at high temperatures.

[0051] When compounded with rubber, such talc improves extrudability and processability, and can enhance the dimensional stability, heat resistance, and weather resistance of rubber products.

[0052] Clay can be viewed as clay, and kaolin clay can be used in the tire industry.

[0053] Clay is a mineral of the aluminosilicate series with a fine plate-like (layered) structure and typically has a white to grayish-white color. Physically, due to its plate-like structure, it allows for processability, light shielding, and surface smoothness, and its functionality improves as the grain size distribution becomes more uniform. Chemically, it is chemically stable due to its resistance to acid-base reactions and remains stable even at high temperatures.

[0054] Barium sulfate is a white crystalline substance with a specific gravity of approximately 4.5, making it one of the heavy inorganic fillers. It is naturally obtained from the mineral barite, but it can also be synthesized. Due to its physically high specific gravity, it is relatively heavy and dense among fillers.

[0055] Chemically, it is highly stable as it does not react well with acids or alkalis. Additionally, when compounded with rubber, it can improve viscosity stability and extrudability.

[0056] Silica is an inorganic oxide derived from sand and quartz, and precipitated silica can be used.

[0057] Silica can be used as a substitute or complement to carbon black. It has low rolling resistance and excellent wear resistance, although it may be slightly inferior to the wear resistance of carbon black.

[0058] Since silica is water-friendly (hydrophilic) and has low compatibility with the polymer rubber matrix, it must be used with a silane coupling agent (silane) to ensure dispersion and bonding strength.

[0059] Fumed silica is an ultrafine (nm-scale) amorphous silica obtained by burning SiCl4 in a hydrogen-oxygen flame, characterized by very small particles and a large surface area (BET). Consequently, thixotropy may occur during rubber compounding.

[0060] Thixotropy refers to time-dependent shear thinning. In other words, it means that viscosity gradually decreases when stirred or sheared, and recovers over time when shearing is stopped.

[0061] In addition, the pigment additive in the present invention may be composed of one or more selected from the group consisting of carbon black, calcium carbonate (CaCO3), talc, clay, barium sulfate (BaSO4), silica, fumed silica, hydrophobic fumed silica, silanized zeolite, and silica aerogel.

[0062] Hydrophobic fumed silica can make its surface hydrophobic by substituting the silanol (-Si-OH) on the surface of the fumed silica with silane or siloxane.

[0063] Silanized zeolite refers to a powder in which an organosilane (-Si-R) is condensed / substituted with the -Si-OH / -Al-OH on the surface of a zeolite (molecular sieve) to make the outer surface hydrophobic and low-polar.

[0064] These silanized zeolites can have internal micropores (molecular sieve function) that selectively adsorb moisture and polar components, and an external surface that improves wettability and dispersibility with respect to the base rubber.

[0065] For example, silanized zeolite 3A may be included, as silanized zeolite 3A has excellent selective moisture adsorption properties, which can suppress bubble formation during tire vulcanization and maintain low loss in dielectric properties.

[0066] In addition, it can help with thixotropy caused by fumed silica or hydrophobic fumed silica, which can be advantageous for coating processes using a coating applicator.

[0067] Hydrophobic silica aerogel can be in the form of an amorphous powder with internal micropores. Silica aerogel has a low relative permittivity (ε). r Dielectric properties having a low loss tangent (tanδ) can be imparted. For example, silica aerogel may be included through methyl / siloxane treatment.

[0068] In the present invention, the permittivity (ε) is the relative permittivity (ε r It means ε r (= ε / ε0). In the present invention, the lower the relative permittivity of the coating layer formed by the coating composition, the more advantageous it may be for RFID communication.

[0069] When the permittivity ε_eff of the effective medium that the antenna of an RFID tag surrounds increases, the existing frequency matching may be distorted because the resonance moves downward. In other words, the existing frequency matching may change as the resonance frequency decreases.

[0070] Conversely, if ε_eff decreases, it helps return to the existing frequency band (e.g., 900 MHz).

[0071] In addition, the radiation resistance of small antennas in a non-magnetic environment is generally determined by the permittivity (ε). r If ) is low, the ratio of loss component to radiation component improves, increasing efficiency, and consequently, RSSI / read distance becomes favorable.

[0072] That is, relative permittivity (εr The lower the relative permittivity, the more advantageous it is for RFID communication.

[0073] According to one embodiment of the present invention, the ratio of the base rubber and the pigment additive may be composed of 1:0.3 to 1:10.

[0074] FIG. 1 is a schematic diagram of an RFID tag according to an embodiment of the present invention. Referring to FIG. 1, an RFID tag according to an embodiment of the present invention comprises: a substrate (100); an RFID chip (200) formed on the substrate; a primer layer (300) applied on the substrate (100) and the RFID chip (200); and a coating layer (400) applied on the primer layer (300), wherein the coating layer (400) may be configured to include the coating composition.

[0075] The substrate (100) can be formed in various shapes and is not limited to those shown in the drawings. Additionally, the substrate may be a PCB substrate. A PCB substrate refers to a printed circuit board (PCB), which is an article composition in which copper foil for wiring is formed into a single shape by using techniques such as pattern printing and etching on a substrate in which copper plates are laminated. A printed circuit board configured in this way can be used in various electronic devices (home appliances, computers, mobile communication devices, or satellites, etc.) with components such as semiconductors, capacitors, or resistors mounted thereon.

[0076] The PCB substrate may be made of paper phenol, glass epoxy (FR-4), glass substrate epoxy (CEM-1, CEM-3), Teflon, metal, or ceramic, but is not limited thereto. Preferably, FR-4 (Flame Retardant-4) material may be used as the PCB substrate.

[0077] When FR-4 is used as the substrate (100), the wireless identification tag can be manufactured to be lightweight and thin, and may have the effect of having high heat resistance.

[0078] The RFID chip (200) refers to a chip that enables RFID communication, and an antenna installed on the substrate (100) may be connected to the RFID chip (200) and formed in a streamlined shape, and may also be a transponder equipped with an antenna inside the RFID chip (200) as needed.

[0079] The primer layer (300) can be formed by applying a primer. The primer may use a liquid polymer compound having a solid content of 26 to 30% and a viscosity of 800 to 1500 cps, but is not limited thereto.

[0080] By having the above primer with the above solid content and the above viscosity, the wettability of the primer applied to the surface of the PCB substrate (100) is improved, so that the bonding strength with the rubber solution can be improved, and the phenomenon of the film thickness becoming thin due to sagging of the liquid coating material before drying can be reduced.

[0081] The above primer is a liquid mixture and may use resins such as polyamide, polyester, polyurethane, epoxy, synthetic resin, and polyolefin, but is not limited thereto. Preferably, the above primer may be a polyolefin resin.

[0082] The above polyolefin resin may be a polyolefin resin having at least one reactive functional group with respect to an indeterminate ink and a rubber solution, but is not limited thereto.

[0083] When the above polyolefin resin is used as the primer, the adhesion to the indeterminate ink coated on the PCB substrate (100) and the rubber solution described later can be excellent, and the adhesion can be excellent even at a usage temperature of 100°C or higher.

[0084] The above primer comprises 45 to 50 parts by weight of xylene (C6H4(CH3)2) and ethylbenzene (C8H2) based on 100 parts by weight of the base rubber. 10 It may be composed of one or more selected from 25 to 35 parts by weight of ) zinc oxide (ZnO), 1 to 5 parts by weight of carbon black (C), 0.1 to 1.0 parts by weight of silica (SiO2), 10 to 15 parts by weight of synthetic resin, and 5 to 10 parts by weight of modified polyethylene.

[0085] The above coating layer (400) can be formed by applying the coating composition described above.

[0086] For example, the coating composition is introduced into a dispenser, and the coating layer can be formed using the coating composition discharged from the dispenser. The thickness of the coating layer (400) formed in this way can be formed in the range of 0.3 mm to 1.5 mm.

[0087] In addition, according to one embodiment of the present invention, the antenna coupled to the surface of the RFID tag by the coating layer can be formed so that it is not completely visible.

[0088] <Example 1>

[0089] A coating composition was prepared comprising 100 parts by weight of base rubber, 25 parts by weight of carbon black, and 5 parts by weight of calcium carbonate. That is, a coating composition was prepared with 30 parts by weight of pigment additive relative to 100 parts by weight of base rubber.

[0090] At this time, the base rubber was prepared by including 60 parts by weight of liquid natural rubber (NR) and 40 parts by weight of liquid butadiene rubber (BR) to have a ratio of natural rubber (NR) to butadiene rubber (BR) of 6:4.

[0091] In addition, a coating agent was prepared by dissolving CMB rubber containing all of the pigment additives in the base rubber in an organic solvent.

[0092] <Example 2>

[0093] A coating composition identical to that of Example 1 was prepared, except that 30 parts by weight of the pigment additive contained 15 parts by weight of carbon black, 5 parts by weight of calcium carbonate, and 10 parts by weight of talc.

[0094] <Example 3>

[0095] A coating composition identical to Example 1 was prepared, except that 30 parts by weight of the pigment additive contained 15 parts by weight of carbon black, 5 parts by weight of calcium carbonate, 5 parts by weight of talc, and 5 parts by weight of clay.

[0096] <Example 4>

[0097] A coating composition identical to that of Example 1 was prepared, except that 30 parts by weight of the pigment additive contained 12 parts by weight of carbon black, 3 parts by weight of calcium carbonate, 5 parts by weight of talc, 5 parts by weight of clay, and 5 parts by weight of barium sulfate.

[0098] <Example 5>

[0099] A coating composition identical to that of Example 1 was prepared, except that 30 parts by weight of the pigment additive contained 12 parts by weight of carbon black, 3 parts by weight of calcium carbonate, 3 parts by weight of talc, 3 parts by weight of clay, 4 parts by weight of barium sulfate, and 5 parts by weight of silica.

[0100] <Example 6>

[0101] A coating composition identical to that of Example 1 was prepared, except that 30 parts by weight of the pigment additive contained 10 parts by weight of carbon black, 5 parts by weight of calcium carbonate, 3 parts by weight of talc, 3 parts by weight of clay, 4 parts by weight of barium sulfate, and 5 parts by weight of hydrophobic fumed silica.

[0102] <Example 7>

[0103] A coating composition identical to that of Example 1 was prepared, except that 30 parts by weight of the pigment additive contained 10 parts by weight of carbon black, 3 parts by weight of calcium carbonate, 3 parts by weight of talc, 3 parts by weight of clay, 3 parts by weight of barium sulfate, 3 parts by weight of hydrophobic fumed silica, and 5 parts by weight of silanized zeolite.

[0104] <Example 8>

[0105] A coating composition identical to that of Example 1 was prepared, except that 30 parts by weight of the pigment additive contained 10 parts by weight of carbon black, 3 parts by weight of calcium carbonate, 3 parts by weight of talc, 3 parts by weight of clay, 3 parts by weight of barium sulfate, 3 parts by weight of hydrophobic fumed silica, 3 parts by weight of silanized zeolite, and 2 parts by weight of silica aerogel.

[0106] <Comparative Example 1>

[0107] The base rubber was prepared by including 60 parts by weight of natural rubber (NR) and 40 parts by weight of butadiene rubber (BR), with a ratio of natural rubber (NR) to butadiene rubber (BR) of 6:4. This is the same ratio of base rubber as in Example 1. However, Comparative Example 1 differs in that solid rubber was used because it is a solid topping (lamination).

[0108] A topping rubber sheet was manufactured by mixing 100 parts by weight of base rubber and 45 parts by weight of carbon black.

[0109] <Comparative Example 2>

[0110] A base rubber identical to that of Comparative Example 1 was manufactured and used, and a topping rubber sheet was manufactured by formulating to include 100 parts by weight of base rubber, 45 parts by weight of carbon black, and 20 parts by weight of silica.

[0111] In the above Examples 1 to 8, a coating layer was formed by applying it to an RFID tag with a length of 40.0 mm, a width of 3.0 mm, and a thickness of 2.0 mm using a coating application device.

[0112] Comparative Examples 1 and 2 above laminated the topping rubber sheet onto the upper and lower parts of RFID tags of the same size as Examples 1 to 8.

[0113] <Experimental Example 1>

[0114] Each of the 10 RFID tags manufactured according to Examples 1 to 8 and Comparative Examples 1 and 2 was vulcanized and embedded in a tire of the same specifications, and then a bubble verification experiment was conducted. At this time, the bubble verification experiment was conducted using an Air coupled ultrasonic scanning device.

[0115] The ROI of the air-coupled ultrasonic scan device was set to 10×10 mm, and the area ratio (%) of the generated bubbles and the maximum diameter (mm) of the generated bubbles were measured. The experimental results are shown in Table 1 below.

[0116] Sample Area ratio (%) Maximum diameter (mm) Example 1 0.45 1.01 Example 2 0.40 0.95 Example 3 0.36 0.88 Example 4 0.34 0.87 Example 5 0.30 0.72 Example 6 0.22 0.61 Example 7 0.16 0.55 Example 8 0.10 0.50 Comparative Example 1 1.40 2.50 Comparative Example 2 0.90 1.80

[0117] Referring to Table 1, it is confirmed that Examples 1 to 8 generated significantly fewer bubbles compared to Comparative Examples 1 and 2, and the maximum diameter of the generated bubbles was also smaller. Accordingly, it can be confirmed that bubble generation can be suppressed when using the coating composition according to the embodiments of the present invention.

[0118] In addition, it can be seen that as we move from Example 1 to Example 8, the bubble generation rate decreases and the maximum diameter also decreases.

[0119] <Experimental Example 2>

[0120] Each of the 10 RFID tags manufactured according to Examples 1 to 8 and Comparative Examples 1 and 2 was vulcanized and embedded in a tire of the same specifications, and then a 90° T-peel test (peel strength test) was performed by cutting a portion of the tire. A universal testing machine (UTM) was used for this purpose.

[0121] The experimental results are as shown in Table 2 below.

[0122] Sample Peel strength (N / 25 mm) Example 1 32.0 Example 2 33.1 Example 3 34.5 Example 4 35.2 Example 5 37.0 Example 6 39.1 Example 7 41.0 Example 8 43.2 Comparative Example 1 22.4 Comparative Example 2 27.3

[0123] Referring to Table 2, Examples 1 to 8 show significantly increased peel strength values ​​compared to Comparative Examples 1 and 2. Accordingly, it can be confirmed that when the coating composition according to the embodiment of the present invention is used, adhesion is improved and the peel strength value increases. This appears to reflect that the interfacial wettability is improved and stress relief is achieved in the coating composition according to the embodiment of the present invention.

[0124] In addition, it can be observed that the peel strength increases sequentially from Example 1 to Example 8, which can be interpreted as the peel strength increasing further as talc, clay, and barium sulfate are added.

[0125] <Experimental Example 3>

[0126] Each of the 10 RFID tags manufactured according to Examples 1 to 8 and Comparative Examples 1 and 2 was vulcanized and embedded in a tire of the same specifications, and then dielectric property tests were conducted on each of the 10 RFID tags.

[0127] Dielectric property experiments were conducted in the UHF band of 860–960 MHz, and the relative permittivity (ε r The dielectric loss tangent (tan δ, dielectric loss tangent, loss tangent) and the loss tangent were measured. A microstrip ring resonator (MSRR) was used, and the experimental results are shown in Table 3 below.

[0128] Sample Relative permittivity (ε r ) Loss tangent (tan δ) Example 1 4.61 0.024 Example 2 4.44 0.022 Example 3 4.29 0.021 Example 4 4.13 0.019 Example 5 3.59 0.018 Example 6 3.43 0.013 Example 7 3.09 0.011 Example 8 2.76 0.009 Comparative Example 1 5.66 0.035 Comparative Example 2 4.54 0.020

[0129] Referring to Table 3, Examples 1 to 8 do not show a significant decrease in relative permittivity or loss tangent (dielectric loss) compared to Comparative Examples 1 and 2.

[0130] The smaller the measured relative permittivity and the smaller the loss tangent, the better the RFID tag measurement performance.

[0131] In Examples 6, 7, and 8, it can be confirmed that the relative permittivity and the loss tangent are significantly reduced, which is interpreted as hydrophobic fumed silica, silanized zeolite, and silica aerogel as pigment additives contributing to the reduction in relative permittivity and the loss tangent.

[0132] <Experimental Example 4>

[0133] Each of the 10 RFID tags manufactured according to Examples 1 to 8 and Comparative Examples 1 and 2 was vulcanized and embedded in a tire of the same specifications, and then an RF reading test was performed on each of the 10 RFID tags.

[0134] The minimum reading distance (m) was measured using an RFID reader capable of reading in the UHF band of 860–960 MHz. The measurement results are shown in Table 4 below.

[0135] Sample Minimum reading distance (m) Example 1 3.8 Example 2 3.9 Example 3 4.0 Example 4 4.1 Example 5 4.2 Example 6 4.8 Example 7 5.0 Example 8 5.2 Comparative Example 1 3.3 Comparative Example 2 3.5

[0136] Referring to Table 4, it can be seen that Examples 1 to 8 did not significantly increase the minimum reading distance compared to Comparative Examples 1 and 2, but secured a relatively excellent minimum reading distance.

[0137] The longer the measured minimum reading distance, the better the RFID tag communication performance, which is considered to be related to the results in Table 3.

[0138] It can be seen that the minimum reading distance increased significantly in Examples 6, 7, and 8, while the carbon black content gradually decreased in Examples 6, 7, and 8.

[0139] In other words, it can be interpreted that the communication distance decreases as the relative permittivity and loss tangent increase with increasing carbon black content, and as the carbon black content decreases, the relative permittivity and loss tangent decrease, which can be interpreted as increasing the minimum read distance.

[0140] In addition, the above experimental results can be interpreted as indicating that communication performance was improved by the use of hydrophobic fumed silica, silanized zeolite, and silica aerogel as pigment additives, which contributed to the reduction of relative permittivity and loss tangent.

[0141] It should be made clear that the above embodiments are merely illustrative and not limiting, and that modifications to components that can be equivalently substituted within the scope of the technical spirit or field of the present invention provided by the following claims are considered to be within the scope of the present invention. Explanation of the symbols

[0143] 100: Substrate 200: RFID chip 300: Primer layer 400: Coating layer

Claims

Claim 1 A coating composition for rubber lamination replacement for tire embedded RFID tags comprising a base rubber and a pigment additive, wherein the pigment additive comprises carbon black, talc, calcium carbonate (CaCO3), clay, barium sulfate (BaSO4), hydrophobic fumed silica, and silanized zeolite. Claim 2 delete Claim 3 An RFID tag comprising a coating composition according to claim 1, a substrate; an RFID chip formed on the substrate; a primer layer applied on the substrate and the RFID chip; and a coating layer applied on the primer layer; wherein the coating layer comprises the coating composition. Claim 4 An RFID tag according to claim 3, characterized in that the thickness of the coating layer is 0.3 mm to 1.5 mm, and the antenna coupled to the surface of the RFID tag is formed so as not to be visible by the coating layer. Claim 5 An RFID tag characterized by forming the coating layer with the coating composition using a coating application device in paragraph 3.

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