Integrated electronic tag and continuous roll-to-roll manufacturing method thereof

Abstract

The invention relates to the technical field of flexible electronic device manufacturing, in particular to an integrated electronic tag and a continuous roll-to-roll manufacturing method thereof. In the label, a substrate layer and a packaging layer are both made of first ethylene vinyl acetal resin; the functional layer is formed by printing an ink composition containing second ethylene vinyl acetal resin as a binder; the first resin and the second resin are both resins prepared by performing acetalation reaction on ethylene-vinyl acetate copolymer, the ethylene unit contents of the first resin and the second resin are both 25 mol% to 60 mol%, the acetalation degree of the first resin is 20 mol% to 35 mol%, and the acetalation degree of the second resin is 10 mol% to 25 mol%. According to the preparation method, an ethylene vinyl acetal resin system with specific chemical homology and composition gradient design is adopted, and an online hot pressing process is matched, so that deep mutual diffusion and entanglement of polymer molecular chains of all layers at an interface are promoted, and a firm and integrated body fusion interface is formed.

Description

Technical Field

[0001] This invention relates to the field of flexible electronic device manufacturing technology, and in particular to an integrated electronic tag and its continuous roll-to-roll manufacturing method. Background Technology

[0002] Flexible electronic tags integrating radio frequency identification (RFID) and temperature sensing functions are key components of the sensing layer of the Internet of Things (IoT) and are widely used in logistics, retail, and traceability. These tags typically employ a multi-layered composite structure comprising a flexible substrate, a printed functional layer, and a transparent protective layer.

[0003] Currently, the industry commonly employs multilayer heterogeneous material composite technology. For example, the substrate typically uses films such as polyethylene terephthalate (PET) and polyimide (PI), the functional layer is printed with conductive inks using acrylic resin, polyurethane, or other adhesives, and the protective layer is laminated to the substrate with adhesives. This technical approach has the following inherent drawbacks: First, the interfacial bonding between materials with different chemical properties is weak, relying mainly on physical adsorption or external adhesives. Under dynamic stresses such as repeated bending and temperature / humidity cycling, interlayer delamination, blistering, or circuit breakage can easily occur, severely affecting the long-term reliability of the labels. Second, the production process is usually a discrete "separate then combined" model, generally including multiple independent steps such as substrate film preparation, offline printing, drying and curing, protective film lamination, and die-cutting. This model is cumbersome, has a long production cycle, and high energy consumption, making it difficult to achieve high-efficiency, low-cost large-scale manufacturing.

[0004] In existing technologies, some solutions attempt to improve production efficiency or interfacial bonding, but these do not fundamentally solve the problem. For example, some solutions (CN114013112A) employ roll-to-roll continuous production processes, but still rely on adhesives for interlayer bonding, failing to address the inherently weak interfacial bonding of heterogeneous materials. Other solutions (CN215416711U and CN218585350U) stack different polymer layers and use adhesives to enhance the physical strength or specific functions of the label. However, this is essentially a mechanical composite of multiple heterogeneous materials, with the interface depending on the adhesive's adhesion force. This carries the risk of adhesive layer aging and fatigue failure, and the manufacturing process inevitably involves multiple independent preparation and composite steps, making it impossible to achieve truly efficient and low-cost integrated continuous manufacturing.

[0005] Therefore, there is an urgent need in this field for an innovative solution that can fundamentally enhance interlayer bonding and adapt to high-speed continuous production, so as to overcome the core bottlenecks of flexible electronic tags in terms of long-term reliability and large-scale manufacturing cost. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the prior art by providing an integrated electronic tag and its continuous roll-to-roll manufacturing method. By using an ethylene vinyl acetal resin system with specific chemical homology and compositional gradient design, combined with an online hot pressing process, the polymer molecular chains of each layer undergo deep interdiffusion and entanglement at the interface, forming a strong, integrated bulk fusion interface.

[0007] To achieve the above objectives, the present invention provides an integrated electronic tag comprising a laminated base layer, a functional layer, and an encapsulation layer, wherein the base layer and the encapsulation layer are both composed of a first vinyl acetal resin; and the functional layer is formed by printing an ink composition containing a second vinyl acetal resin as a binder. The first ethylene vinyl acetal resin and the second ethylene vinyl acetal resin are both resins obtained by acetalization reaction of ethylene-vinyl acetate copolymer. The ethylene unit content of both is in the range of 25 mol% to 60 mol%, and the degree of acetalization of the first ethylene vinyl acetal resin is 20 mol% to 35 mol%, while the degree of acetalization of the second ethylene vinyl acetal resin is 10 mol% to 25 mol%.

[0008] Preferably, the ethylene unit content of the first ethylene vinyl acetal resin is 40 mol% to 55 mol%.

[0009] Preferably, the ethylene unit content of the second ethylene vinyl acetal resin is 30 mol% to 45 mol%.

[0010] Preferably, the acetal groups in the first and second ethylene vinyl acetal resins are both derived from aliphatic aldehydes with 4 to 7 carbon atoms.

[0011] The present invention also provides a continuous roll-to-roll manufacturing method for the integrated electronic tag, comprising the following steps performed online in sequence: S1. Base film forming: The first ethylene vinyl acetal resin is melted, plasticized, and cast to form a base layer film; S2. Online printing of functional layer: In the temperature range where the base film is in a viscoelastic state, an ink composition containing a second vinyl acetal resin is printed on its surface to form a functional pattern and then dried. S3. Encapsulation layer lamination: A first vinyl acetal resin melt is coated on the dried surface of the functional layer to form an encapsulation layer; S4. Online hot-press fusion: The composite structure consisting of a base layer, a functional layer and an encapsulation layer is hot-pressed to fuse the layers together at the interface, resulting in an integrated electronic tag.

[0012] Preferably, in S1, the temperature for melting and plasticizing is 160°C to 200°C.

[0013] Preferably, in S2, the temperature range of the viscoelastic state is 10°C above the glass transition temperature Tg of the substrate film to 30°C below its melting point Tm.

[0014] Preferably, in S2, the printing method is gravure printing or flexographic printing.

[0015] Preferably, in S4, the hot pressing conditions are: temperature 100°C to 140°C, and linear pressure 30 N / cm to 100 N / cm.

[0016] The present invention also provides a smart packaging product comprising the aforementioned integrated electronic tag.

[0017] The beneficial effects of this invention are as follows: (1) This invention employs an ethylene vinyl acetal resin system with specific chemical homology and compositional gradient design. By ensuring that the first and second resins are within a specific range in terms of ethylene unit content, and by making the degree of acetalization of the first resin higher than that of the second resin, combined with an online hot-pressing process, deep interdiffusion and entanglement of polymer molecular chains occur at the interface of each layer, forming a strong and integrated bulk fusion interface. This eliminates the dependence on external adhesives in traditional technologies and the resulting weak interface problem, resulting in labels with extremely high interlayer bonding strength and excellent resistance to bending fatigue. Under dynamic stress and harsh environments (such as high temperature and high humidity), delamination, blistering, or circuit breakage are not easily observed, and long-term reliability is significantly improved.

[0018] (2) This invention innovatively integrates traditionally separate multi-process steps (such as independent film making, offline printing, independent lamination and coating) into a continuous production line of "substrate forming - online printing - encapsulation and lamination - online hot pressing". This process realizes online, continuous and seamless manufacturing from resin raw materials to integrated label substrate, greatly reducing production links, shortening the production cycle, and reducing energy consumption and labor costs. Compared with the existing technology, even if a roll-to-roll form is used, it still relies on multiple steps of preparation and lamination. This invention provides a practical and feasible innovative path for realizing large-scale, low-cost manufacturing of electronic tags.

[0019] (3) Based on the design principle of the homologous resin system of this invention, by adjusting the specific parameters of the first and second resins (such as ethylene content, degree of acetalization, and aldehyde type) and the thickness of each layer, the physical properties of the final label, such as flexibility, modulus, and transparency, can be precisely controlled within a wide range to meet the needs of different application scenarios, from rigid packaging to flexible wearable devices. In addition, the platform can be compatible with and easily integrate multiple functional layers such as conductive, sensing, and optical indication, and can simultaneously endow the label with RFID identification and temperature response functions, demonstrating strong functional integration and expansion potential, and possessing strong platform technology advantages. Detailed Implementation

[0020] The present invention provides an integrated electronic tag comprising a laminated base layer, a functional layer and an encapsulation layer, wherein the base layer and the encapsulation layer are both composed of a first vinyl acetal resin; the functional layer is formed by printing an ink composition containing a second vinyl acetal resin as a binder. The first ethylene vinyl acetal resin and the second ethylene vinyl acetal resin are both resins obtained by acetalization reaction of ethylene-vinyl acetate copolymer. The ethylene unit content of both is in the range of 25 mol% to 60 mol%, and the degree of acetalization of the first ethylene vinyl acetal resin is 20 mol% to 35 mol%, while the degree of acetalization of the second ethylene vinyl acetal resin is 10 mol% to 25 mol%.

[0021] In this invention, the ethylene unit content (i.e., the ethylene unit content in the raw material ethylene-vinyl acetate copolymer) of the first ethylene vinyl acetal resin is 40 mol% to 55 mol%.

[0022] In this invention, the ethylene unit content (i.e., the ethylene unit content in the raw material ethylene-vinyl acetate copolymer) of the second ethylene vinyl acetal resin is 30 mol% to 45 mol%.

[0023] In this invention, the acetal groups in the first and second ethylene vinyl acetal resins are both derived from aliphatic aldehydes with 4 to 7 carbon atoms.

[0024] In this invention, the fatty aldehyde is selected from n-butyraldehyde or isobutyraldehyde.

[0025] In this invention, the thickness of the substrate layer and the encapsulation layer are each independently between 10 μm and 100 μm.

[0026] In this invention, the functional layer is at least one of the following: a conductive circuit layer (circuit such as an RFID antenna for signal transmission or identification), a sensing circuit layer (element such as a temperature sensor or humidity sensor for environmental perception), and an optical functional layer (layer such as a light-shielding layer or a fluorescent layer for optical control or indication).

[0027] The present invention also provides a continuous roll-to-roll manufacturing method for the integrated electronic tag, comprising the following steps performed online in sequence: S1. Base film forming: The first ethylene vinyl acetal resin is melted, plasticized, and cast to form a base layer film; S2. Online printing of functional layer: In the temperature range where the base film is in a viscoelastic state, an ink composition containing a second vinyl acetal resin is printed on its surface to form a functional pattern and then dried. S3. Encapsulation layer lamination: A first vinyl acetal resin melt is coated on the dried surface of the functional layer to form an encapsulation layer; S4. Online hot-press fusion: The composite structure consisting of a base layer, a functional layer and an encapsulation layer is hot-pressed to fuse the layers together at the interface, resulting in an integrated electronic tag.

[0028] In this invention, in S1, the melting and plasticizing temperature is 160°C to 200°C.

[0029] In this invention, in S2, the temperature range of the viscoelastic state is 10°C above the glass transition temperature Tg of the substrate film to 30°C below its melting point Tm.

[0030] In this invention, in S2, the printing method is gravure printing or flexographic printing.

[0031] In this invention, the hot pressing conditions in S4 are: temperature 100°C to 140°C, and linear pressure 30 N / cm to 100 N / cm.

[0032] In this invention, in S4, the hot pressing device is a pair of metal rollers with controllable surface temperature.

[0033] The present invention also provides a smart packaging product comprising the aforementioned integrated electronic tag.

[0034] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0035] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0036] The raw materials and their sources used in the following embodiments and comparative examples of this invention are as follows: Ethylene-vinyl acetate copolymer (EVA) resin was purchased from DuPont (e.g., Elvax series) or Arkema (e.g., Evatane series); aldehyde reagents were commercially available chemically pure or analytically pure products; flake-shaped nano-silver powder was purchased from Ferro Inc. or Guizhou Platinum Industry Co., Ltd.; thermochromic microcapsules were purchased from Merck Group or Shenzhen Yihua Technology Development Co., Ltd.; polyethylene terephthalate (PET) film, acrylic pressure-sensitive adhesive film, and commercial solvent-based silver paste are all commonly used materials in the electronics industry and can be purchased from suppliers such as Dow Chemical, 3M, Teijin, and Fujikura Chemical.

[0037] Example 1 This embodiment provides a continuous roll-to-roll manufacturing method for an integrated electronic tag with RFID wireless identification function, including the following steps performed online in sequence: (1) Raw materials and formula First, an ethylene vinyl acetal resin (used in the base layer and encapsulation layer): Using EVA resin (DuPont Elvax 40W) with an ethylene unit content of 48 mol% as raw material and n-butyraldehyde as the aldehyde source, a solution-based acetalization reaction was carried out under p-toluenesulfonic acid catalysis. The reaction conditions were controlled as follows: the molar ratio of EVA to n-butyraldehyde was 1:0.35, the reaction temperature was 80℃, and the reaction time was 4 h, yielding a target resin with an acetalization degree of 28 mol%. Differential scanning calorimetry (DSC, using a PerkinElmer DSC8000, heating rate 10 K / min) determined its glass transition temperature (Tg) to be 45℃ and its melting point (Tm) to be 160℃.

[0038] Second ethylene vinyl acetal resin (binder in functional layer ink compositions): Using EVA resin (Arkema Evatane 1020VN) with an ethylene unit content of 38 mol% as raw material and n-butyraldehyde as aldehyde source, a solution acetalization reaction was carried out under the catalysis of p-toluenesulfonic acid. The reaction conditions were controlled as follows: the molar ratio of EVA to n-butyraldehyde was 1:0.22, the reaction temperature was 75℃, and the reaction time was 3h, to obtain the target resin with an acetalization degree of 18 mol% and a Tg of 52℃.

[0039] Ink composition (for printing UHF RFID antennas): By weight, 15 parts of second vinyl acetal resin were dissolved in 72 parts of a mixed solvent consisting of ethanol and propylene glycol methyl ether (ethanol to propylene glycol methyl ether mass ratio of 7:3), and then 13 parts of flake-shaped nano silver powder (Ferro AS-0110, average particle size D50 of 2μm) were added. After initial mixing using a high-speed disperser, the mixture was transferred to a sand mill for grinding and dispersion for 2 hours until the fineness was less than 5μm, thus obtaining the ink composition.

[0040] (2) Preparation Base film forming: First ethylene vinyl acetal resin is fed into a twin-screw extruder and fully melted and plasticized at 180°C. Then it is extruded through a T-die and cast onto a mirror-cooled steel roller with a surface temperature set at 30°C. After rapid cooling and shaping, a continuous base layer film with a thickness of 30μm and a width of 300mm is formed.

[0041] Online printing of the functional layer: The base layer film is pulled forward by guide rollers. When it reaches the printing unit, its surface temperature is monitored in real time by a non-contact infrared thermometer. When the film surface temperature reaches 90°C (this temperature is 45°C above the resin Tg and 70°C below Tm, in a viscoelastic state), it immediately enters the gravure printing machine. Using a gravure roller with a screen ruling of 250 lines per inch, the ink composition prepared above is precisely printed onto the film surface to form a preset UHF RFID antenna pattern (designed frequency of 925MHz). The printed film then passes through a 3-meter-long hot air drying tunnel set at 80°C for approximately 30 seconds to ensure complete solvent evaporation.

[0042] Encapsulation layer lamination: A second extrusion coating die is set above the dried antenna pattern surface. The first ethylene vinyl acetal resin is melted at 175°C and uniformly coated onto the functional layer through this die to form a continuous encapsulation layer with a thickness of 20 μm.

[0043] Online hot-press fusion: The composite film carrying the three-layer structure is immediately placed between a pair of heated steel rollers. The surface temperature of both the upper and lower rollers is controlled at 120°C, and the gap between the two rollers is set to generate a linear pressure of 60 N / cm (adjusted by a pneumatic system). Under these conditions, the three resin layers undergo thermally induced molecular chain movement, interdiffusion, and entanglement at the interface, achieving intrinsic fusion.

[0044] Rewinding and Post-Processing: The fused film passes through a cooling section and is finally wound into a roll by a rewinding roller to obtain an integrated electronic tag. After the integrated electronic tag is cut, an anisotropic conductive adhesive film (ACF, Hitachi Chemical Co., Ltd. Anisolm series) is used at the pre-designed antenna chip bonding points to bind an Impinj Monza R6 UHF RFID chip under the process conditions of a hot press head temperature of 120°C, a pressure of 0.8MPa, and a bonding time of 3 seconds, finally producing the finished tag.

[0045] Example 2 This embodiment provides a continuous roll-to-roll manufacturing method for an integrated electronic tag that combines temperature sensing and optical indication functions, including the following steps performed online sequentially: (1) Raw materials and formula The first and second ethylene vinyl acetal resins are the same as those in Example 1.

[0046] Add microencapsulated thermochromic pigment to the encapsulation layer (to give the encapsulation layer optical indication function): During the melting process of the first vinyl vinyl acetal resin, add 0.5% of the total mass of the resin microencapsulated thermochromic pigment (Merck Group Licochrome thermochromic pigment, color change temperature of 30°C) and mix evenly.

[0047] Ink composition (for printing temperature sensors): By weight, 15 parts of second vinyl acetal resin were dissolved in 70 parts of a mixed solvent consisting of ethanol and propylene glycol methyl ether (ethanol to propylene glycol methyl ether mass ratio of 7:3), followed by the addition of 15 parts of conductive carbon black (Cabot Corporation Vulcan XC72R). After initial mixing using a high-speed disperser, the mixture was then transferred to a sand mill for grinding and dispersion for 2 hours until the fineness was less than 5 μm, thus obtaining the ink composition.

[0048] (2) Preparation Basement membrane molding: Same as in Example 1.

[0049] Online printing functional layer: Same as in Example 1, but due to the different ink composition formulation, a resistive temperature sensor circuit pattern is formed on the film surface after printing.

[0050] Encapsulation layer lamination: A second extrusion coating die is set above the dried sensor pattern surface. The first vinyl acetal resin and microencapsulated thermochromic pigment are melted at 175°C and uniformly coated onto the functional layer through this die to form a continuous encapsulation layer with a thickness of 20 μm.

[0051] Online hot-press fusion: The composite film carrying the three-layer structure is immediately placed between a pair of heated steel rollers. The surface temperature of both the upper and lower rollers is controlled at 100°C, and the gap between the two rollers is set to generate a linear pressure of 50 N / cm (adjusted by a pneumatic system). Under these conditions, the three resin layers undergo thermally induced molecular chain movement, interdiffusion, and entanglement at the interface, achieving intrinsic fusion.

[0052] Rewinding and Post-Processing: The fused film passes through a cooling section and is finally wound into a roll by a winding roller to obtain an integrated electronic tag. Subsequent processing such as slitting and die-cutting can be performed according to specific application requirements, and it can be connected to an external reading circuit to form a complete temperature sensing and optical indication system, resulting in the finished tag.

[0053] Example 3 This embodiment provides a continuous roll-to-roll manufacturing method for an integrated electronic tag with RFID wireless identification function. By adjusting the resin composition and process parameters in Embodiment 1, the flexibility and bending performance of the tag are improved. Specifically, the method includes the following steps performed online in sequence: (1) Raw materials and formula First, an ethylene vinyl acetal resin (used in the base layer and encapsulation layer): Using EVA resin (DuPont Elvax 660) with an ethylene unit content of 55 mol% as raw material and isobutyraldehyde as the aldehyde source, a solution-based acetalization reaction was carried out under p-toluenesulfonic acid catalysis. The reaction conditions were controlled as follows: the molar ratio of EVA to isobutyraldehyde was 1:0.28, the reaction temperature was 85℃, and the reaction time was 3.5 h, yielding a target resin with an acetalization degree of 22 mol%. Differential scanning calorimetry (DSC, using PerkinElmer DSC 8000, heating rate 10 K / min) determined its glass transition temperature (Tg) to be 38℃ and its melting point (Tm) to be 148℃.

[0054] Second ethylene vinyl acetal resin (binder in functional layer ink compositions): Using EVA resin (DuPont Elvax 460) with an ethylene unit content of 45 mol% as raw material and n-butyraldehyde as aldehyde source, a solution acetalization reaction is carried out under the catalysis of p-toluenesulfonic acid. The reaction conditions are controlled as follows: the molar ratio of EVA to n-butyraldehyde is 1:0.18, the reaction temperature is 70℃, and the reaction time is 2.5h, to obtain the target resin with an acetalization degree of 12 mol% and a Tg of 50℃.

[0055] Ink composition: Same as in Example 1.

[0056] (2) Preparation It is basically the same as Example 1, except that: The thickness of both the base layer and the encapsulation layer was adjusted to 25μm; during online hot pressing fusion, the surface temperature of the upper and lower pressure rollers was adjusted to 110℃, and the linear pressure was adjusted to 40N / cm.

[0057] Comparative Example 1 This comparative example provides a method for manufacturing electronic tags, employing a conventional heterogeneous material system and a multi-step discrete process, including the following steps: A 50μm thick biaxially oriented PET film (Teijin Lumirror® series, Japan) was used as the substrate. A UHF RFID antenna pattern, identical to that in Example 1, was formed on the PET film using commercial solvent-based silver paste (Fujikura Chemicals Dotite® XA-430S, Japan) via screen printing, followed by drying in a 120°C oven for 3 minutes. A 50μm thick transparent PET film coated with acrylic pressure-sensitive adhesive (3M 300LSE) was used as a protective layer and laminated onto the dried conductive circuit at room temperature using a laminator. After slitting the laminated material (electronic tag), an Impinj Monza R6 UHF RFID chip was bonded to the pre-designed antenna chip bonding points using an anisotropic conductive adhesive film (ACF, Hitachi Chemicals Anisolm series) under hot press conditions of 120°C, 0.8MPa, and 3 seconds, resulting in the final product tag.

[0058] Comparative Example 2 This comparative example provides a method for manufacturing an electronic tag, using the same resin material system as the examples, but manufactured using a multi-step discrete discontinuous process, including the following steps: (1) Raw materials and formula Same as Example 1.

[0059] (2) Preparation Independent preparation of the base layer film: The first ethylene vinyl acetal resin was melt-cast and then cooled and completely cured to obtain a base film roll with a thickness of 30 μm.

[0060] Offline printing and drying: At room temperature (25°C), the ink composition is gravure printed onto the surface of the substrate film to form an antenna pattern, and then dried in an 80°C oven for 5 minutes.

[0061] Independent preparation of encapsulation film: First ethylene vinyl acetal resin is melt-cast, cooled and solidified, and cut into encapsulation film with a thickness of 20 μm.

[0062] Lamination: The encapsulation film is placed on the printed and dried base layer and fed into a flatbed laminator. It is then hot-pressed at 120°C and 0.6MPa for 10 seconds to achieve two-layer lamination.

[0063] Winding and post-processing: The composite material is wound up to obtain an electronic tag. The finished tag can then be manufactured using the same chip bonding process as in Example 1.

[0064] Comparative Example 3 This comparative example provides a method for manufacturing an electronic tag, including the following steps: (1) Raw materials and formula First, an ethylene vinyl acetal resin was prepared using EVA resin with an ethylene unit content of 60 mol% as raw material and n-butyraldehyde as the aldehyde source. A solution-based acetalization reaction was carried out under p-toluenesulfonic acid catalysis. The reaction conditions were controlled as follows: the molar ratio of EVA to n-butyraldehyde was 1:0.50, the reaction temperature was 90℃, and the reaction time was 5 h, yielding a target resin with an acetalization degree of 40 mol%. Differential scanning calorimetry (DSC, using a PerkinElmer DSC 8000, heating rate 10 K / min) determined its glass transition temperature (Tg) to be 65℃ and its melting point (Tm) to be 170℃.

[0065] Second ethylene vinyl acetal resin: Using EVA resin with an ethylene unit content of 25 mol% as raw material and n-butyraldehyde as aldehyde source, a solution acetalization reaction was carried out under the catalysis of p-toluenesulfonic acid. The reaction conditions were controlled as follows: the molar ratio of EVA to n-butyraldehyde was 1:0.08, the reaction temperature was 60℃, and the reaction time was 1.5h, to obtain the target resin with an acetalization degree of 5 mol% and a Tg of 60℃.

[0066] Ink composition: Same as in Example 1.

[0067] (2) Preparation An attempt was made to prepare the film according to "(2)" in Example 1. However, the two resins used had significant differences in key properties: the first resin exhibited higher Tg and Tm due to its high ethylene content and high degree of acetalization, and also had a high melt viscosity; the second resin, on the other hand, had different thermal properties and rheological behavior due to its low ethylene content and low degree of acetalization. After the encapsulation layer composite step, the composite structure exhibited severe curling, interlayer slippage, and overall wrinkling due to the mismatch in thermal shrinkage rate, modulus, and melt compatibility of the two materials, making it impossible to obtain a smooth and firm integrated film, and the process failed.

[0068] Experimental Example 1 The electronic tags and finished tags prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to the following performance tests.

[0069] (1) Peel strength test: According to the ASTM D3330 standard test method, the electronic tag was subjected to a 90° peel test using a universal testing machine (peel speed 300 mm / min). Five samples were tested in each group, and the average value of the results was taken.

[0070] (2) Dynamic bending test: According to IPC-TM-650 test method 2.4.3, the finished product label was installed on the bending tester. The bending radius was set to 5.0 mm in Examples 1-2 and Comparative Examples 1-2, and 3.0 mm in Example 3. After each 1000 bending cycles, the test was paused and the antenna resistance value was measured. The resistance change rate (ΔR / R0) after 100,000 consecutive bending cycles was recorded.

[0071] (3) High temperature and high humidity environment reliability test: The electronic tag was placed in a constant temperature and humidity test chamber and accelerated aging test was carried out under the harsh conditions of 85℃ temperature and 85% relative humidity. After being placed for 500 hours, it was taken out and cooled and equilibrated in a standard laboratory environment for 24 hours before the peel strength retention rate was tested.

[0072] The performance test results are recorded in Table 1.

[0073] Table 1 Performance Test Results

[0074] In Table 1, 1 indicates that when Comparative Example 1 is bent 50,000 times, the resistance increases by more than 25% on average, resulting in localized stripping of the circuit, and the test is terminated. 2 indicates that, in Comparative Example 1, after 200 hours, the protective layer showed extensive blistering and delamination, resulting in complete failure.

[0075] From Table 1, it can be seen that (1) Examples 1-3 all exhibit excellent comprehensive performance. The high peel strength proves that the interface formed by the homologous resin system and the body through online hot pressing has excellent bonding force. The extremely low resistance change rate after bending and the high strength retention rate after environmental aging verify the long-term reliability of the integrated structure under dynamic mechanical stress and harsh environment. (2) Example 2 maintains good mechanical and environmental reliability while integrating temperature and visualization functions, proving the functional integration feasibility of the technical platform of the present invention. (3) Example 3: The performance is stable under more demanding bending conditions (3.0 mm radius), meeting the requirements of high flexibility applications. (4) Comparative Example 1: The interlayer bonding force is weak, and the bending resistance and environmental reliability are poor, reflecting the inherent defects of the heterogeneous material composite system that relies on physical adhesion. (5) Comparative Example 2: Although the same resin material is used, the interface fusion is insufficient due to the multi-step discrete process. Although its various properties are better than those of Comparative Example 1, they are significantly lower than those of the example prepared by the continuous process of the present invention, proving the key role of the online integrated continuous manufacturing process in improving performance.

[0076] Experimental Example 2 The finished tags from Example 1 underwent radio frequency performance testing: In an anechoic chamber, an ETSI-compliant UHF RFID reader (transmit power 30dBm) was used to scan within the 865-928MHz frequency band, and the maximum reading distance at the 925MHz center frequency was measured. The test results showed that the maximum reading distance of the finished tags in Example 1 was 7.5m.

[0077] Experimental Example 3 The electronic tag prepared in Example 2 was subjected to specific functional tests to verify its dual functions of temperature sensing and optical indication: (1) Visual temperature response test: According to GB / T 30706-2014, observe the color change of the electronic tag encapsulation layer with temperature. The test results show that when the temperature exceeds its color change temperature (30℃), the color of the encapsulation layer undergoes a reversible change (such as changing from blue to white), and the response is obvious.

[0078] (2) Resistance-Temperature Characteristic Test: According to IEC 60751, the resistance temperature sensor integrated with the tag was placed in a temperature-controlled environment ranging from 20℃ to 60℃, and its resistance value was measured. The results show that the sensor resistance has a good linear relationship with temperature, and the linear fitting determination coefficient R0 is [value missing]. 2 >0.99, the sensitivity meets the design requirements.

[0079] (3) Thermal shock cycle test: The label was subjected to 10 thermal shock cycles from -20℃ to 60℃. After the test, the color indication function remained normal and the baseline drift rate of the sensor resistance value was <2%, showing good functional stability.

[0080] As can be seen, Example 2 successfully integrates resistance temperature sensing and thermochromic optical indication into a single tag structure. Test results show that both functions are effective and reliable, and can withstand certain temperature shocks, fully verifying the feasibility and advantages of the technical solution of this invention for manufacturing multifunctional integrated smart tags.

[0081] Therefore, the present invention employs the above-mentioned integrated electronic tag and its continuous roll-to-roll manufacturing method. By using an ethylene vinyl acetal resin system with specific chemical homology and compositional gradient design, combined with an online hot pressing process, the polymer molecular chains of each layer undergo deep interdiffusion and entanglement at the interface, forming a strong, integrated bulk fusion interface.

[0082] Finally, it should be noted that the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An integrated electronic tag, comprising a laminated substrate layer, a functional layer, and an encapsulation layer, characterized in that, Both the base layer and the encapsulation layer are made of a first vinyl acetal resin; the functional layer is formed by printing an ink composition containing a second vinyl acetal resin as a binder. The first ethylene vinyl acetal resin and the second ethylene vinyl acetal resin are both resins obtained by acetalization reaction of ethylene-vinyl acetate copolymer. The ethylene unit content of both is in the range of 25 mol% to 60 mol%, and the degree of acetalization of the first ethylene vinyl acetal resin is 20 mol% to 35 mol%, while the degree of acetalization of the second ethylene vinyl acetal resin is 10 mol% to 25 mol%.

2. The integrated electronic tag according to claim 1, characterized in that, The ethylene unit content of the first ethylene vinyl acetal resin is 40 mol% to 55 mol%.

3. The integrated electronic tag according to claim 1 or 2, characterized in that, The ethylene unit content of the second ethylene vinyl acetal resin is 30 mol% to 45 mol%.

4. The integrated electronic tag according to claim 1, characterized in that, The acetal groups in both the first and second ethylene vinyl acetal resins originate from aliphatic aldehydes with 4 to 7 carbon atoms.

5. The continuous roll-to-roll manufacturing method of the integrated electronic tag according to any one of claims 1 to 4, characterized in that, The following steps are performed online in sequence: S1. Base film forming: The first ethylene vinyl acetal resin is melted, plasticized, and cast to form a base layer film; S2. Online printing of functional layer: In the temperature range where the base film is in a viscoelastic state, an ink composition containing a second vinyl acetal resin is printed on its surface to form a functional pattern and then dried. S3. Encapsulation layer lamination: A first vinyl acetal resin melt is coated on the dried surface of the functional layer to form an encapsulation layer; S4. Online hot-press fusion: The composite structure consisting of a base layer, a functional layer and an encapsulation layer is hot-pressed to fuse the layers together at the interface, resulting in an integrated electronic tag.

6. The continuous roll-to-roll manufacturing method according to claim 5, characterized in that, In S1, the melting and plasticizing temperature is 160°C to 200°C.

7. The continuous roll-to-roll manufacturing method according to claim 5, characterized in that, In S2, the temperature range of the viscoelastic state is from 10°C above the glass transition temperature Tg of the substrate film to 30°C below its melting point Tm.

8. The continuous roll-to-roll manufacturing method according to claim 5, characterized in that, In S2, the printing method is either gravure printing or flexographic printing.

9. The continuous roll-to-roll manufacturing method according to claim 5, characterized in that, In S4, the hot pressing conditions are: temperature 100℃ to 140℃, and linear pressure 30N / cm to 100N / cm.

10. A smart packaging product, characterized in that, It includes the integrated electronic tag as described in any one of claims 1 to 4.

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