Heat-induced irreversible color change anti-uncovering transfer sealing anti-counterfeiting label and manufacturing method thereof

Abstract

The invention provides a heat-induced irreversible color-changing anti-uncovering transfer sealing anti-counterfeiting label and a manufacturing method thereof, and relates to the technical field of anti-counterfeiting packaging materials, the heat-induced irreversible color-changing anti-uncovering transfer sealing anti-counterfeiting label comprises a base material layer, an anti-transfer glue layer, a heat-induced irreversible color-changing ink layer and a surface protection layer which are sequentially arranged from bottom to top, and all the layers are tightly attached to form an integrated structure; wherein the base material layer is a polyethylene glycol terephthalate film, and the raw materials of the anti-transfer adhesive layer are composed of a two-component solvent-free polyurethane adhesive, a fluorine modified acrylate copolymer and a silane coupling agent. The heat-induced irreversible color-changing ink layer is prepared from the following raw materials: spiropyrane microcapsule pigment, fluorine-modified polyurethane resin, fatty alcohol-polyoxyethylene ether sodium sulfate and deionized water, and the surface protection layer is a polytrifluorochloroethylene resin layer. According to the invention, double anti-counterfeiting cooperation of high-temperature warning and anti-transfer is realized, and the risk of anti-counterfeiting failure in a high-temperature environment is avoided; and the application range is wide, and the diversified anti-counterfeiting requirements of high-end products are met.

Description

Technical Field

[0001] This invention relates to the field of anti-counterfeiting packaging materials technology, specifically to a thermochromic irreversible color-changing anti-tampering and transfer-proof sealing anti-counterfeiting label and its manufacturing method. It is suitable for sealing packaging of products such as food, medicine, cosmetics, and electronic products that need to be protected from high-temperature opening and transfer, achieving dual anti-counterfeiting protection. Background Technology

[0002] In the fields of commodity circulation, logistics and transportation, and high-end product packaging, anti-counterfeiting sealing stickers are a key measure to ensure product authenticity and packaging integrity. Their reliability and stability directly affect corporate brand value and consumers' legitimate rights. Currently, most mainstream anti-counterfeiting sealing stickers on the market adopt the classic structure of "adhesive + fragile paper." This structure, with its advantages of simple manufacturing process and low cost, is widely used in sealing and anti-counterfeiting scenarios for various commodities such as food, pharmaceuticals, and electronic products. However, with the upgrading of anti-counterfeiting technologies, the technical shortcomings of such traditional anti-counterfeiting sealing stickers are becoming increasingly apparent, making it difficult to meet the stringent requirements of the high-end market for highly secure anti-counterfeiting packaging.

[0003] Specifically, the shortcomings of the traditional "self-adhesive label + fragile paper" structure lie in the insufficient performance of the adhesive layer and the limitations of the anti-transfer design. Most existing self-adhesive adhesives are ordinary pressure-sensitive adhesive systems with poor heat resistance. In the high-temperature environments commonly encountered during commodity storage and transportation (such as open-air transport vehicles and high-temperature warehouses in summer), they are prone to softening and melting, leading to a significant decrease in adhesive layer tack and a sharp reduction in bonding strength. Even if the "open and break" anti-counterfeiting logic is achieved by relying on the physical brittleness of the fragile paper, with the adhesive layer softened, criminals can use methods such as slow peeling or low-temperature assisted peeling to transfer fragments of the fragile paper bearing the anti-counterfeiting label, either completely or partially, to the packaging seal of counterfeit products. This results in the illegal reuse of the anti-counterfeiting label, directly rendering the anti-counterfeiting measures ineffective and causing significant economic losses to businesses and consumers. In addition, the bonding strength between traditional self-adhesive adhesive layers and substrates and fragile paper is not stable enough. Some products may experience edge lifting due to vibration and temperature changes before normal opening, which not only affects the appearance of the packaging, but also provides an opportunity for criminals to tamper with it.

[0004] To enhance anti-counterfeiting levels, the industry is gradually incorporating thermochromic technology into anti-counterfeiting sealing sticker design. Among these, thermochromic irreversible inks, with their "one-time trigger, permanent color change" characteristic, have become a key research focus. These inks undergo irreversible chemical structural changes at specific temperature thresholds, resulting in a permanent color transition and providing a clear indication of whether the packaging has been tampered with at high temperatures or illegally opened. However, the application of existing thermochromic inks in anti-counterfeiting sealing stickers faces several bottlenecks: Firstly, most existing thermochromic inks are solvent-based systems, which are environmentally unfriendly and lack compatibility with fragile paper and common substrates, leading to issues such as ink flaking and unstable color-changing sensitivity after printing. Secondly, these inks are often printed as independent anti-counterfeiting marks on the sealing sticker surface, failing to functionally synergize with the anti-transfer structure. Even if the ink changes color, criminals can still reuse the anti-counterfeiting mark by transferring it to the main structure of the sealing sticker, failing to fundamentally eliminate the risk of anti-counterfeiting failure.

[0005] From the current state of development of anti-transfer label technology, existing solutions mostly rely on physical damage. Besides the aforementioned fragile paper structures, these include designs such as film tear-type and microneedle-type destructive labels, but all have significant drawbacks. Film tear-type labels, even after the adhesive layer softens, can still achieve partial and complete transfer by controlling the peeling force; microneedle-type labels, due to their complex manufacturing process and high cost, are difficult to scale up. More importantly, existing anti-transfer technologies are not integrated with temperature warning functions, failing to effectively prevent the core risk of "illegal opening and transfer under high-temperature environments." In sectors with extremely high requirements for warehousing and transportation conditions and anti-counterfeiting security, such as high-end liquor, imported pharmaceuticals, and precision electronic components, goods not only need anti-tampering and anti-transfer functions but also require intuitive visual signals (such as color changes) to alert consumers or regulators whether the packaging has been tampered with at high temperatures. Current technologies cannot simultaneously meet both of these core requirements.

[0006] In summary, existing anti-counterfeiting sealing labels generally suffer from poor heat resistance and insufficient reliability in preventing transfer. Furthermore, the integration of thermochromic irreversible color-changing technology and anti-transfer technology is low, lacking an integrated anti-counterfeiting label that simultaneously provides high-temperature irreversible color-changing warnings and strong anti-tampering and transfer capabilities. With the market's continued increase in demand for high-security anti-counterfeiting packaging, developing an anti-counterfeiting sealing label that can withstand high-temperature environments and combines intuitive color-changing warnings with highly effective anti-transfer functions has become a pressing technical challenge in the current packaging anti-counterfeiting field. Summary of the Invention

[0007] The present invention addresses the aforementioned shortcomings of the prior art by providing a thermo-irreversible color-changing, tamper-evident, transfer-proof anti-counterfeiting label and its manufacturing method.

[0008] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a thermo-irreversible color-changing anti-tampering and transfer-proof sealing anti-counterfeiting label, comprising a substrate layer, an anti-transfer adhesive layer, a thermo-irreversible color-changing ink layer, and a surface protective layer arranged sequentially from bottom to top, with each layer tightly bonded together to form an integrated structure; The substrate layer is a polyethylene terephthalate film; The anti-transfer adhesive layer is composed of the following raw materials by mass percentage: 92-95% two-component solvent-free polyurethane adhesive, 4-6.5% fluorine-modified acrylate copolymer, and 1-1.5% silane coupling agent; The thermotropic irreversible color-changing ink layer is composed of the following raw materials by mass percentage: 25-30% spiropyran microcapsule pigment, 60-65% fluorine-modified polyurethane resin, 1-2% sodium fatty alcohol polyoxyethylene ether sulfate, and the balance deionized water. The surface protective layer is a polychlorotrifluoroethylene resin layer.

[0009] In some preferred embodiments of the present invention, the thickness of the substrate layer is 25-35 μm.

[0010] In some preferred embodiments of the present invention, the two-component solvent-free polyurethane adhesive has a solid content of 100% and a viscosity of 2000-2500 mPa・s / 25℃. In the two-component solvent-free polyurethane adhesive, agent A is an aliphatic hydroxyl-terminated polyester polyol with a number average molecular weight of 1000-2000 and a hydroxyl value of 56-112 mgKOH / g, and agent B is a hexamethylene diisocyanate trimer. The mass ratio of agent A to agent B is 10:1.

[0011] Preferably, the aliphatic hydroxyl-terminated polyester polyol used in Agent A of the two-component solvent-free polyurethane adhesive is at least one of poly(1,4-butanediol adipate), poly(1,6-hexanediol adipate), poly(1,4-butanediol glutarate), and poly(1,4-butanediol succinate).

[0012] In some preferred embodiments of the present invention, the fluorinated modified acrylate copolymer is a random copolymer of n-pentyl methacrylate and 2,2,3,3-tetrafluoropropyl acrylate, with a fluorine content of 13%, a glass transition temperature Tg = 25°C, a viscosity of 1200-1500 mPa·s / 25°C, and a structural formula of -[-CH2C(CH3)(COOC5H 11 )-co-CH2CH(COOCH2CF2CF3)-] n - where n is the number-average degree of polymerization, an integer ranging from 60 to 80, and -co- indicates random copolymerization.

[0013] In some preferred embodiments of the present invention, the silane coupling agent is KH-550.

[0014] In some preferred embodiments of the present invention, the thickness of the anti-transfer adhesive layer is 12-16 μm, and the anti-transfer adhesive layer undergoes irreversible cross-linking and curing at a high temperature of ≥80°C.

[0015] In some preferred embodiments of the present invention, the core material to wall material of the spiropyran microcapsule pigment has a mass ratio of 1:3, with 1,3,3-trimethylindole-6'-nitrobenzodihydropyran as the core material and polyurea as the wall material, and an average particle size of 2-3 μm.

[0016] Furthermore, the preparation method of the spiropyran microcapsule pigment is as follows: S1. Take 1,3,3-trimethylindole-6'-nitrobenzenedihydropyran, add ethyl acetate, and stir at 50℃ and 500 r / min for 15 min to prepare a core material organic solution; add Tween 80 and continue stirring for 10 min to obtain a core material dispersion. S2. Take the polyurea prepolymer, add anhydrous ethanol to dilute it, stir for 5 minutes until the system is transparent, and prepare the wall material prepolymer solution. S3. Slowly drop the core material dispersion into deionized water and emulsify it at 1500 r / min for 25 min to form a water-in-oil emulsion. The core material droplet size in the emulsion is controlled at 1-2 μm. Add ethylenediamine to the emulsion, heat to 60℃, reduce the stirring speed to 800 r / min, and keep the reaction at this temperature for 60 min. S4. After cooling to room temperature, centrifuge at 8000 r / min for 15 min, wash, dry at 60℃ for 24 h, pass through a 200 mesh sieve and grind to obtain spiropyran microcapsule pigments.

[0017] Further, in step S1, the mass ratio of Tween 80, ethyl acetate, and 1,3,3-trimethylindole-6'-nitrobenzodihydropyran is 1:20:10.

[0018] Furthermore, in step S2, the mass ratio of polyurea prepolymer to anhydrous ethanol is 1:3.

[0019] Furthermore, in step S3, the amount of deionized water used is 5 times the mass of the core material dispersion, and the amount of ethylenediamine added is 8% of the mass of the polyurea prepolymer.

[0020] In some preferred embodiments of the present invention, the thickness of the thermochromic irreversible color-changing ink layer is 6-9 μm, and the thermochromic irreversible color-changing ink layer permanently changes from red to colorless at a high temperature of ≥80℃.

[0021] In some preferred embodiments of the present invention, the fluorinated modified polyurethane resin is a block copolymer of polyoxyethylene ether diol-hexamethylene diisocyanate and fluorinated side-chain polyoxyethylene ether diol-cyclohexyl diisocyanate, with a fluorine content of 9%, a solid content of 45%, a viscosity of 1800-2200 mPa·s / 25℃, and a structural formula of -[-O-(CH2CH2O). x -CONH-(CH2)6-NHCO-] m -b-[-O-(CH2CH2O) y -CONH-C6H 11 -NHCO-O-CH2CH2CF3-] n - where m, n, x, and y are number-average aggregation degrees, m is an integer ranging from 100 to 140, n is an integer ranging from 20 to 25, x and y are integers ranging from 10 to 15, and -b- indicates block copolymerization.

[0022] In some preferred embodiments of the present invention, the polychlorotrifluoroethylene resin has a molecular weight of 50,000-80,000, a melting point of 210-215°C, and a fluorine content of 76-78%.

[0023] In some preferred embodiments of the present invention, the thickness of the surface protective layer is 5-7 μm.

[0024] Secondly, the present invention provides a method for manufacturing the above-mentioned thermotropic irreversible color-changing tamper-evident transfer sealing anti-counterfeiting label, comprising the following steps: (1) Pretreatment of substrate layer: The polyethylene terephthalate film is subjected to corona treatment, then the surface is wiped with anhydrous ethanol and dried in an oven at 55-60℃ for 8-10 minutes for later use; (2) Preparation and coating of anti-transfer adhesive layer: Take two-component solvent-free polyurethane adhesive, fluorinated modified acrylate copolymer and silane coupling agent, add them to a high-speed disperser, disperse at 800-1000 r / min for 30-35 min, and mix evenly; use a comma doctor blade coater to coat the mixed adhesive solution on the surface of the pretreated substrate layer, and then dry in an oven at 65-70℃ for 12-15 min to form an anti-transfer adhesive layer; (3) Printing of thermochromic irreversible color-changing ink layer: First, mix spiropyran microcapsule pigment with deionized water and grind it with a sand mill until the particle size is ≤5μm. Then, add fluorine-modified polyurethane resin and fatty alcohol polyoxyethylene ether sodium sulfate and stir at 600-800r / min for 20-25min to prepare thermochromic irreversible color-changing ink. Print the thermochromic irreversible color-changing ink on the surface of the anti-transfer adhesive layer using a flexographic printing press and dry it at 85-90℃ for 15-20min to form a thermochromic irreversible color-changing ink layer. (4) Preparation and lamination of surface protective layer: Polychlorotrifluoroethylene resin is added to tetrahydrofuran and stirred and dissolved at 40℃ and 500r / min to prepare a protective coating liquid with a solid content of 35-40%; the coating liquid is coated on the surface of the thermo-irreversible color-changing ink layer using a coating machine, and then dried in an oven at 100-105℃ for 25-30min and cooled to room temperature; (5) Post-processing: The product is cut into preset sizes by a slitting machine and then rolled up to obtain the finished anti-counterfeiting label.

[0025] Furthermore, in step (1), the power of the corona treatment is 35-40 W / m. 2 The processing time is 3-4 seconds, so that the surface tension of the substrate is ≥38mN / m.

[0026] Furthermore, in step (2), the coating speed is 15-18 m / min and the blade gap is 0.015 mm.

[0027] Furthermore, in step (3), the grinding media of the sand mill is zirconia beads with a diameter of 0.8 mm, the grinding speed is 2800 r / min, and the grinding time is 60-90 min; Furthermore, in step (3), the printing pressure is 0.3-0.4 MPa and the printing speed is 12-15 m / min.

[0028] Furthermore, in step (4), the coating speed is 14-16 m / min and the gap between the coating nozzles is 0.01 mm.

[0029] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1. This solution deeply integrates thermochromic irreversible color-changing technology with anti-transfer technology. Through a layered structure design, the thermochromic irreversible color-changing ink layer and the anti-transfer adhesive layer achieve functional synergy. The anti-transfer adhesive layer uses a two-component solvent-free polyurethane adhesive and a fluorinated modified acrylate copolymer compound system. It undergoes irreversible cross-linking and curing at ≥80℃, maintaining excellent adhesion strength (retention rate ≥88%) even at 80℃, ensuring complete breakage and no transfer of residues when the label is removed. Simultaneously, the thermochromic irreversible color-changing ink layer uses spiropyran microcapsule pigments as its core. It undergoes permanent color change (from red to colorless) at ≥77℃, with a color difference ΔE ≥4.5 after color change. This provides a clear and intuitive warning signal to consumers or regulatory personnel that the packaging has been exposed to high temperatures, allowing for early detection of the risk of unauthorized opening. The combination of the thermochromic irreversible color-changing ink layer and the anti-transfer adhesive layer achieves dual anti-counterfeiting synergy of high-temperature warning and anti-transfer, eliminating the risk of anti-counterfeiting failure under high-temperature conditions.

[0030] 2. This solution significantly improves heat resistance and stability, making it suitable for harsh warehousing and transportation environments. Through optimized formulation of the anti-transfer adhesive layer and the synergistic effect of the surface protective layer, the heat resistance of the label is greatly enhanced. The fluorinated modified acrylate copolymer (13% fluorine content) added to the anti-transfer adhesive layer complements the two-component solvent-free polyurethane adhesive, effectively improving the high-temperature resistance and interfacial bonding stability of the adhesive layer. The surface protective layer uses high-fluorine-content polychlorotrifluoroethylene resin, further blocking the impact of high temperatures on the internal structure. Test results show that after being kept at 80℃ for 24 hours, the label of this invention exhibits no edge curling or softening, and the adhesive strength retention rate reaches 88-94%, far superior to traditional acrylate pressure-sensitive adhesive labels (retention rate of only 35%). This characteristic allows the label to stably adapt to harsh environments such as open-air transport vehicles in summer and high-temperature warehouses, solving the technical problem of performance degradation of existing labels under high-temperature conditions.

[0031] 3. This solution offers stable and reliable adhesion, with a more durable anti-transfer effect. The anti-transfer adhesive layer, enhanced with a silane coupling agent (KH-550), strengthens the interfacial bond with the substrate layer (polyethylene terephthalate film). At room temperature, the adhesive strength reaches 7.2-8.1 N / 12 mm, significantly higher than traditional self-adhesive labels (4.3 N / 12 mm). Simultaneously, the irreversible cross-linking curing characteristics of the adhesive layer ensure long-term stability of the adhesive performance. Whether at room temperature or high temperature, the label completely breaks upon peeling, avoiding the partial transfer problem caused by adhesive layer softening in traditional labels. Furthermore, the thermochromic irreversible color-changing ink layer uses an emulsion-type fluorinated modified polyurethane resin as a film-forming agent, exhibiting excellent compatibility with the anti-transfer adhesive layer and surface protective layer. Printing does not affect the overall adhesive performance of the label, achieving a balance between anti-counterfeiting functionality and adhesive performance.

[0032] 4. This solution boasts excellent surface durability, making it suitable for large-scale distribution scenarios. A protective layer of polychlorotrifluoroethylene (PTFE) resin is applied to the outermost layer. This resin possesses excellent wear resistance, corrosion resistance, and scratch resistance. Combined with the fluorine-modified components in the anti-transfer adhesive layer, this gives the label excellent surface durability. Test results show that after 50 cycles of abrasion using a 1kg abrasive device, the printed pattern on the label remains clear and undamaged, far superior to traditional labels without a protective layer. This characteristic ensures that the label is less prone to wear and tear due to friction and collision during large-scale distribution processes such as loading, unloading, transportation, and warehousing, guaranteeing the continuity of its anti-counterfeiting function.

[0033] 5. This solution boasts excellent environmental friendliness and process adaptability, facilitating large-scale production. The thermochromic irreversible ink utilizes a water-based system with deionized water as the solvent, combined with emulsion-type fluorinated modified polyurethane resin. Compared to existing solvent-based thermochromic inks, this significantly reduces VOC emissions, enhancing environmental friendliness during production and use. The anti-transfer adhesive layer employs a two-component solvent-free polyurethane adhesive with 100% solids content, eliminating solvent evaporation pollution. Furthermore, the manufacturing method of this invention employs mature processes such as corona treatment, comma blade coating, flexographic printing, and lamination coating. Parameters at each step are controllable, equipment is highly versatile, requiring no specialized high-end equipment, and the preparation processes for each layer exhibit good compatibility. The reasonable drying temperature and time enable continuous, large-scale production, balancing technological advancement with industrial applicability.

[0034] 6. This solution has a wide range of applications, meeting the diverse anti-counterfeiting needs of high-end products. The label has multiple advantages, including high-temperature warning, strong anti-transfer, and high durability. The size can be flexibly adjusted by cutting, making it suitable for sealing and packaging of various products that need to be protected from high-temperature opening and transfer, such as food, medicine, cosmetics, and electronic products. It is especially suitable for fields with extremely high requirements for warehousing and transportation conditions and anti-counterfeiting security, such as high-end liquor, imported medicines, and precision electronic components. Its intuitive color-changing warning function reduces the difficulty of identification for consumers and regulatory personnel, and its strong anti-transfer performance protects the brand value of enterprises. Attached Figure Description

[0035] Figure 1 The image shows a comparison of the adhesive strength of the labels in Examples 1-3 and Comparative Examples 1-3 after heat resistance at room temperature and 80℃ / 24h.

[0036] Figure 2 The curves show the change in the retention rate (%) of the adhesive strength of the labels applied in Examples 1-3 and Comparative Examples 1-3 at -80℃.

[0037] Figure 3 Comparison of the anti-transfer performance levels of the labels of Examples 1-3 and Comparative Examples 1-3 at room temperature and high temperature (Grade A = 3 points, Grade B = 2 points, Grade C = 1 point).

[0038] Figure 4 Comparison of the thermochromic properties of the labels in Examples 1-3 and Comparative Examples 1-3; (a) complete color change temperature; (b) color difference ΔE 24h after color change (ΔE ≥ 3.0 indicates obvious color change).

[0039] Figure 5 The temperature-color difference (ΔE) variation curves of the labels in Examples 1-3 are shown.

[0040] Figure 6 Comparison of the surface abrasion resistance grades of the labels of Examples 1-3 and Comparative Examples 1-3 (50 round trips of 1kg sanding). Detailed Implementation

[0041] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0042] In the following embodiments of the present invention, all raw materials used, unless otherwise specified, are commercially available products. Two-component solvent-free polyurethane adhesive: Agent A is poly(1,4-butanediol adipate) diol with a number average molecular weight of 1500±50 and a hydroxyl value of 75±2 mgKOH / g; Agent B is hexamethylene diisocyanate trimer. The mass ratio of Agent A to Agent B is 10:1. After mixing, the solid content is 100%, and the viscosity is 2200±100 mPa·s / 25℃. Fluorine-modified acrylate copolymer: a random copolymer of n-pentyl methacrylate and 2,2,3,3-tetrafluoropropyl acrylate, with a fluorine content of 13±0.5%, a glass transition temperature Tg=25±1℃, and a viscosity of 1350±50 mPa·s / 25℃. Its structural formula is -[-CH2C(CH3)(COOC5H 11 )-co-CH2CH(COOCH2CF2CF3)-] n - where n is 70±2, and -co- indicates random copolymerization. Fluorine-modified polyurethane resin: an emulsion type, a block copolymer of polyoxyethylene ether diol-hexamethylene diisocyanate and fluorinated side-chain polyoxyethylene ether diol-cyclohexyl diisocyanate, with a fluorine content of 9±0.3%, a solid content of 45%, and a viscosity of 2000±100 mPa·s / 25℃. Its structural formula is -[-O-(CH2CH2O)]. x -CONH-(CH2)6-NHCO-] m -b-[-O-(CH2CH2O)y-CONH-C6H 11 -NHCO-O-CH2CH2CF3-] n - where m is 120±3, n is 22±2, x is 12±1, y is 13±1, and -b- indicates block copolymerization. Polychlorotrifluoroethylene resin: molecular weight 65000±2000, melting point 212±1℃, fluorine content 77±0.5%.

[0043] The core material to wall material of the spiropyran microcapsule pigment is in a mass ratio of 1:3, using 1,3,3-trimethylindole-6'-nitrobenzodihydropyran as the core material and polyurea as the wall material. The preparation method of the spiropyran microcapsule pigment is as follows: S1. Take 1,3,3-trimethylindole-6'-nitrobenzodihydropyran, add ethyl acetate, and stir for 15 min at 50℃ and 500 r / min to prepare a core material organic solution; add Tween 80 and continue stirring for 10 min to obtain a core material dispersion; wherein, the mass ratio of Tween 80, ethyl acetate, and 1,3,3-trimethylindole-6'-nitrobenzodihydropyran is 1:20:10. S2. Take the polyurea prepolymer, add anhydrous ethanol to dilute it, stir for 5 minutes until the system is transparent, and prepare the wall material prepolymer liquid; wherein, the mass ratio of polyurea prepolymer to anhydrous ethanol is 1:3.

[0044] S3. Slowly drop the core material dispersion into deionized water and emulsify at 1500 r / min for 25 min to form a water-in-oil emulsion. The core material droplet size in the emulsion is controlled at 1-2 μm. Add ethylenediamine to the emulsion, heat to 60℃, reduce the stirring speed to 800 r / min, and keep the reaction at this temperature for 60 min. The amount of deionized water used is 5 times the mass of the core material dispersion, and the amount of ethylenediamine added is 8% of the mass of the polyurea prepolymer.

[0045] S4. After cooling to room temperature, centrifuge at 8000 r / min for 15 min, wash, dry at 60℃ for 24 h, pass through a 200 mesh sieve and grind to obtain spiropyran microcapsule pigment with an average particle size of 2.5 μm. Example

[0046] The thermochromic irreversible color-changing tamper-evident and transfer-proof sealing anti-counterfeiting label of this embodiment consists of, from bottom to top, a substrate layer, an anti-transfer adhesive layer, a thermochromic irreversible color-changing ink layer, and a surface protective layer. The parameters of each layer are as follows: Substrate layer: Polyethylene terephthalate film, 30 μm thick; Anti-transfer adhesive layer: The raw materials, by mass percentage, consist of 93.5% two-component solvent-free polyurethane adhesive, 5% fluorinated modified acrylate copolymer, and 1.5% silane coupling agent; thickness 14μm; Thermochromic irreversible color-changing ink layer: The raw materials, by mass percentage, consist of 28% spiropyran microcapsule pigment, 63% fluorine-modified polyurethane resin, 1.5% sodium fatty alcohol polyoxyethylene ether sulfate, and 7.5% deionized water; thickness 7μm; Surface protective layer: polychlorotrifluoroethylene resin layer, 6μm thick.

[0047] The manufacturing method of the thermotropic irreversible color-changing tamper-evident transfer sealing anti-counterfeiting label in this embodiment is as follows: (1) Substrate layer pretreatment: The polyethylene terephthalate film was subjected to corona treatment with a treatment power of 38W / m. 2 The processing time is 3.5s to make the surface tension of the substrate ≥38mN / m; then the surface is wiped with anhydrous ethanol and dried in an oven at 58℃ for 9min for later use. (2) Preparation and coating of anti-transfer adhesive layer: Take the two-component solvent-free polyurethane adhesive, fluorinated modified acrylate copolymer and silane coupling agent according to the above ratio, add them to the high-speed disperser, disperse at 900 r / min for 32 min, and mix evenly; use a comma doctor blade coater to coat the mixed adhesive solution on the surface of the pretreated substrate layer, with a coating speed of 16 m / min and a doctor blade gap of 0.015 mm; then dry in an oven at 68℃ for 13 min to form an anti-transfer adhesive layer; (3) Printing of thermochromic irreversible color-changing ink layer: First, mix spiropyran microcapsule pigment with deionized water and grind it with a sand mill (the grinding medium is zirconia beads with a diameter of 0.8 mm, the grinding speed is 2800 r / min, and the grinding time is 75 min) until the particle size is ≤5 μm. Then, add fluorine-modified polyurethane resin and fatty alcohol polyoxyethylene ether sodium sulfate and stir at 700 r / min for 22 min to prepare thermochromic irreversible color-changing ink. Use a flexographic printing press to print the ink on the surface of the anti-transfer adhesive layer. The printing pressure is 0.35 MPa and the printing speed is 13 m / min. Dry at 88℃ for 18 min to form a thermochromic irreversible color-changing ink layer. (4) Preparation and composite of surface protective layer: Polychlorotrifluoroethylene resin was added to tetrahydrofuran and stirred and dissolved at 40℃ and 500r / min to prepare a protective coating liquid with a solid content of 38%; the coating liquid was coated on the surface of the thermo-irreversible color-changing ink layer using a coating machine, and then dried in an oven at 102℃ for 28min and cooled to room temperature. (5) Post-processing: The product is cut into 5cm×3cm size by a slitting machine and then rolled up to obtain the finished anti-counterfeiting label. Example

[0048] The thermochromic irreversible color-changing tamper-evident and transfer-proof sealing anti-counterfeiting label of this embodiment consists of, from bottom to top, a substrate layer, an anti-transfer adhesive layer, a thermochromic irreversible color-changing ink layer, and a surface protective layer. The parameters of each layer are as follows: Substrate layer: Polyethylene terephthalate film, 25 μm thick; Anti-transfer adhesive layer: The raw materials, by mass percentage, consist of 95% two-component solvent-free polyurethane adhesive, 4% fluorinated modified acrylate copolymer, and 1% silane coupling agent; thickness 12μm; Thermochromic irreversible color-changing ink layer: The raw materials, by mass percentage, consist of 25% spiropyran microcapsule pigment, 65% fluorine-modified polyurethane resin, 1% sodium fatty alcohol polyoxyethylene ether sulfate, and 9% deionized water; thickness 6μm; Surface protective layer: polychlorotrifluoroethylene resin layer, 5μm thick.

[0049] The manufacturing method of the thermotropic irreversible color-changing tamper-evident transfer sealing anti-counterfeiting label in this embodiment is as follows: (1) Substrate layer pretreatment: The polyethylene terephthalate film was subjected to corona treatment with a treatment power of 35W / m. 2 The surface tension of the substrate is ≥38mN / m after being processed for 3 seconds. Then, the surface is wiped with anhydrous ethanol and dried in an oven at 55℃ for 8 minutes for later use. (2) Preparation and coating of anti-transfer adhesive layer: Take the raw materials according to the above ratio, add them to the high-speed disperser, disperse at 800 r / min for 30 min, and mix evenly; use a comma doctor blade coater to coat, with a coating speed of 15 m / min and a doctor blade gap of 0.015 mm; then dry in an oven at 65℃ for 12 min to form an anti-transfer adhesive layer; (3) Printing of thermo-irreversible color-changing ink layer: First, mix spiropyran microcapsule pigment with deionized water, grind in a sand mill for 60 min until the particle size is ≤5μm, then add the remaining raw materials, stir at 600r / min speed for 20 min to make ink; flexographic printing, printing pressure 0.3MPa, printing speed 12m / min; dry at 85℃ for 15 min to form ink layer; (4) Preparation and lamination of surface protective layer: Prepare a protective coating liquid with a solid content of 35%; after coating, dry in an oven at 100℃ for 25 min and cool to room temperature; (5) Post-processing: cut into 5cm×3cm sizes and roll up to obtain the finished product. Example

[0050] The thermochromic irreversible color-changing tamper-evident and transfer-proof sealing anti-counterfeiting label of this embodiment consists of, from bottom to top, a substrate layer, an anti-transfer adhesive layer, a thermochromic irreversible color-changing ink layer, and a surface protective layer. The parameters of each layer are as follows: Substrate layer: Polyethylene terephthalate film, 35μm thick; Anti-transfer adhesive layer: The raw materials, by mass percentage, consist of 92% two-component solvent-free polyurethane adhesive, 6.5% fluorinated modified acrylate copolymer, and 1.5% silane coupling agent; thickness 16μm; Thermochromic irreversible color-changing ink layer: The raw materials, by mass percentage, consist of 30% spiropyran microcapsule pigment, 60% fluorine-modified polyurethane resin, 2% sodium fatty alcohol polyoxyethylene ether sulfate, and 8% deionized water; thickness 9μm; Surface protective layer: polychlorotrifluoroethylene resin layer, 7μm thick.

[0051] The manufacturing method of the thermotropic irreversible color-changing tamper-evident transfer sealing anti-counterfeiting label in this embodiment is as follows: (1) Substrate layer pretreatment: Corona treatment power 40W / m 2 Processing time: 4 seconds; surface tension: ≥38 mN / m; wipe with anhydrous ethanol, then dry in an oven at 60℃ for 10 minutes for later use. (2) Preparation and coating of anti-transfer adhesive layer: The raw material is added to a high-speed disperser and dispersed at 1000 r / min for 35 min; the coating speed is 18 m / min and the doctor blade gap is 0.015 mm; the material is dried in an oven at 70℃ for 15 min to form an anti-transfer adhesive layer. (3) Printing of thermo-irreversible color-changing ink layer: Grind in a sand mill for 90 min until the particle size is ≤5μm, add the remaining raw materials and stir at 800r / min for 25 min; flexographic printing pressure is 0.4MPa, printing speed is 15m / min; dry at 90℃ for 20 min to form ink layer; (4) Preparation and lamination of surface protective layer: Prepare a protective coating liquid with a solid content of 40%; dry in an oven at 105℃ for 30 min, and cool to room temperature; (5) Post-processing: cut into 5cm×3cm sizes and roll up to obtain the finished product.

[0052] Comparative Example 1 Adopting the traditional structure of the mainstream "self-adhesive + fragile paper" anti-counterfeiting label, from bottom to top, it consists of a paper substrate, a regular pressure-sensitive adhesive layer, a fragile paper layer, a thermochromic ink layer, and a surface protective layer. The regular pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive, and the fragile paper layer is printed with standard anti-counterfeiting patterns. It is manufactured using conventional processes and cut into 5cm × 3cm sizes.

[0053] Comparative Example 2 The difference from Example 1 is that only the raw material ratio of the anti-transfer adhesive layer is adjusted to: 98.5 wt% two-component solvent-free polyurethane adhesive, 1.5 wt% silane coupling agent, and fluorine-removed modified acrylate copolymer; the parameters and preparation process of the other layers are completely consistent with Example 1.

[0054] Comparative Example 3 Unlike Example 1, the thermo-irreversible color-changing ink layer is removed. The label structure consists of a substrate layer, an anti-transfer adhesive layer, and a surface protective layer stacked sequentially. The parameters (raw material ratio, thickness) and preparation process of the remaining layers are completely consistent with those of Example 1, except that the printing step of the thermo-irreversible color-changing ink layer is omitted.

[0055] Test case Performance tests were conducted on the labels of Examples 1-3 and Comparative Examples 1-3. The test items and methods are as follows: 1. Adhesion strength test: In accordance with JIS Z 0237 (2009) standard, a 180° peel test was used to test the adhesion strength between the label and the stainless steel substrate, in N / 12mm. 2. Heat resistance test: Place the label sample in an 80℃ oven for 24 hours. After taking it out, observe whether there is any peeling or softening. Test its adhesive strength retention rate (adhesive strength after heat resistance / adhesive strength at room temperature × 100%). 3. Anti-transfer performance test: Under normal temperature (25℃) and high temperature (80℃ for 24 hours), the label was slowly peeled off with tweezers. The presence of complete transfer or partial transfer of label fragments was observed and classified into three levels: Level A - No transfer, label completely damaged; Level B - Small amount of fragment transfer, transfer area <5%; Level C - Obvious transfer, transfer area ≥5%. 4. Thermochromic performance test: Referring to GB / T 17001.3—2025 standard, the temperature was gradually increased in a constant temperature oven, and the initial temperature and complete color change temperature of the label were recorded. After the color change, the label was left for 24 hours to observe whether the color recovered, and the color difference ΔE before and after the color change was measured with a colorimeter. ΔE ≥ 3.0 indicates obvious color change. 5. Surface abrasion resistance test: Using a 1kg abrasive device, the label surface is rubbed back and forth 50 times at a speed of 40 times / minute. The clarity of the printed pattern is observed and divided into 3 levels: Excellent - clear pattern without abrasion; Good - pattern with slight abrasion but still recognizable; Poor - pattern with severe abrasion and not recognizable.

[0056] The results of performance tests on the labels of Examples 1-3 and Comparative Examples 1-3 are shown in the table below. Figure 1-6 As shown:

[0057] From the table above and Figure 1-6 The test results show that: 1. Regarding room temperature bonding strength, compared with Comparative Example 1 (4.3 N / 12 mm), the labels of Examples 1-3 all have excellent room temperature bonding strength (7.2-8.1 N / 12 mm), which is close to that of Comparative Example 3 (7.6 N / 12 mm). This indicates that the anti-transfer adhesive layer of the present invention has stronger bonding force with the substrate and the adhered object, and the addition of the thermochromic ink layer does not affect the bonding performance of the label.

[0058] 2. Regarding heat resistance, Examples 1-3 and Comparative Example 3 showed no curling or softening at 80°C, with a bond strength retention rate of 88-94%. Comparative Example 1, however, exhibited significant curling and softening, with a retention rate of only 35%. Comparative Example 2, lacking the fluorinated modified acrylate copolymer, showed slight curling, with a retention rate reduced to 68%. This demonstrates that the anti-transfer adhesive layer formulation of this invention (especially the addition of the fluorinated modified acrylate copolymer) is key to improving the heat resistance stability of the label. Furthermore, the synergistic effect of the surface protective layer and the anti-transfer adhesive layer ensures structural stability at high temperatures, and the presence of the thermochromic ink layer does not affect the heat resistance.

[0059] 3. Regarding anti-transfer performance, Examples 1-3 and Comparative Example 3 all achieved Grade A anti-transfer standard at both room temperature and high temperature, with no transfer phenomenon and the label completely damaged. Comparative Example 1 was Grade B at room temperature, but dropped to Grade C after high temperature, indicating a significant risk of transfer. Comparative Example 2 was Grade A at room temperature, but dropped to Grade B after high temperature, with a small amount of residual material transferring. This demonstrates that the addition of fluorinated modified acrylate copolymer has a significant impact on anti-transfer performance under high temperature conditions. The anti-transfer adhesive layer of this invention undergoes irreversible cross-linking and curing at high temperature, effectively eliminating the risk of transfer upon high-temperature peeling, and the addition of thermochromic ink layer does not weaken the anti-transfer effect.

[0060] 4. Regarding thermochromic performance, the complete color-changing temperature of Examples 1-3 is 77-79℃, which meets the design requirements (color-changing warning completed before ≥80℃). The color difference ΔE reaches 4.5-5.1 after 24 hours of color change, and the color remains unchanged permanently, providing a clear and intuitive high-temperature warning function. In contrast, Comparative Examples 1 and 3 have no color-changing function and cannot provide high-temperature tampering warnings, highlighting the core role of the thermochromic irreversible color-changing ink layer in high-temperature warnings.

[0061] 5. Regarding surface abrasion resistance, Examples 1-3 and Comparative Example 3 all achieved the "Excellent" standard, with the printed pattern or protective layer remaining clear after rubbing, thanks to the protective effect of the surface protective layer. Comparative Example 1 exhibited poor abrasion resistance, while Comparative Example 2, lacking fluorine-modified components, had its abrasion resistance reduced to the "Good" level. This demonstrates that the fluorine-modified components in the surface protective layer and anti-transfer adhesive layer of the present invention synergistically improve the surface durability of the label, and the thermochromic ink layer does not affect the surface protective effect.

[0062] In summary, the thermochromic irreversible color-changing tamper-evident seal anti-counterfeiting label of the present invention achieves a synergistic effect of high-temperature irreversible color-changing warning and strong tamper-evident seal performance through a rational layered structure design and raw material ratio of a substrate layer, an anti-transfer adhesive layer, a thermochromic irreversible color-changing ink layer, and a surface protective layer. It also possesses excellent heat resistance, adhesion stability, and surface durability. Traditional labels cannot meet the requirements for high-temperature resistance and anti-transfer; the lack of fluorinated modified acrylate copolymer weakens heat resistance and anti-transfer performance; and the lack of a thermochromic ink layer results in the loss of high-temperature warning function. The present invention solves these problems simultaneously and is suitable for high-end product packaging fields with extremely high requirements for anti-counterfeiting security and warehousing and transportation conditions.

[0063] Although specific technical solutions of the present invention have been described in detail through embodiments, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the present invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermally induced irreversible color-changing, tamper-evident, peel-to-reveal, tamper-proof sticker, characterized in that, The substrate layer, the anti-transfer adhesive layer, the thermally irreversible color-changing ink layer and the surface protection layer are sequentially arranged from bottom to top and tightly adhere to form an integrated structure. The substrate layer is a polyethylene terephthalate film. The anti-transfer adhesive layer is composed of the following raw materials in percentage by mass: two-component solvent-free polyurethane adhesive 92-95%, fluorine-modified acrylate copolymer 4-6.5%, and silane coupling agent 1-1.5%. The thermally irreversible color-changing ink layer is composed of the following raw materials in percentage by mass: spiropyran microcapsule pigment 25-30%, fluorine-modified polyurethane resin 60-65%, fatty alcohol polyoxyethylene ether sodium sulfate 1-2%, and the balance of deionized water. The surface protection layer is a polytrifluorochloroethylene resin layer.

2. A thermally irreversibly color-changing, tamper-evident, transfer adhesive security label according to claim 1, characterized in that: The two-component solvent-free polyurethane adhesive has a solid content of 100%, a viscosity of 2000-2500 mPa·s / 25℃, and the A component is an aliphatic terminal hydroxyl polyester polyol with a number average molecular weight of 1000-2000 and a hydroxyl value of 56-112 mgKOH / g, and the B component is a hexamethylene diisocyanate trimer, and the mass ratio of the A component to the B component is 10:

1.

3. A thermally irreversibly color-changing, tamper-evident, transfer adhesive security label according to claim 1, characterized in that: The fluorine-modified acrylate copolymer is a random copolymer of n-pentyl methacrylate and 2,2,3,3-tetrafluoropropyl acrylate, with a fluorine content of 13%, a glass transition temperature Tg = 25°C, a viscosity of 1200-1500 mPa·s / 25°C, and a structural formula of -[-CH2C(CH3)(COOC5H 11 )-co-CH2CH(COOCH2CF2CF3)-] n , wherein n is a number average polymerization degree, and is an integer within a range of 60-80, and -co- represents random copolymerization.

4. A thermally irreversibly color-changing, tamper-evident, transfer adhesive security label according to claim 1, characterized in that: The core material and the wall material of the spiropyran microcapsule pigment have a mass ratio of 1:3, the core material is 1,3,3-trimethylindole-6'-nitrobenzodihydropyrane, the wall material is polyurea, and the average particle size is 2-3 μm.

5. A thermally irreversibly color-changing, tamper-evident, transfer adhesive security label according to claim 4, wherein, The preparation method of the spiropyran microcapsule pigment is as follows: S1, take 1,3,3-trimethylindole-6'-nitrobenzodihydropyrane, add ethyl acetate, stir at 50℃, 500r / min for 15min, prepare core material organic solution; add Tween 80, continue to stir for 10min, get core material dispersion liquid, the mass ratio of Tween 80, ethyl acetate, 1,3,3-trimethylindole-6'-nitrobenzodihydropyrane is 1:20:10; S2, take polyurea prepolymer, add anhydrous ethanol for dilution, stir 5min until the system is transparent, prepare wall material prepolymer liquid; wherein, the mass ratio of polyurea prepolymer and anhydrous ethanol is 1:3; S3, slowly drop the core material dispersion liquid into deionized water, emulsify at 1500r / min for 25min to form water-in-oil emulsion, control the particle size of core material droplets in the emulsion to 1-2μm; add ethylenediamine to the emulsion, heat to 60℃, reduce the stirring speed to 800r / min, and keep the reaction for 60min; wherein, the amount of deionized water is 5 times the mass of the core material dispersion liquid, and the amount of ethylenediamine is 8% of the mass of the polyurea prepolymer; S4, after cooling to room temperature, centrifuge at 8000r / min for 15min, wash, dry at 60℃ for 24h, pass through a 200 mesh sieve, and grind to obtain the spiropyran microcapsule pigment.

6. A thermally irreversibly color-changing, tamper-evident, transfer adhesive security label according to claim 1, characterized in that: The fluorine modified polyurethane resin is a block copolymer of polyoxyethylene ether glycol-hexamethylene diisocyanate and fluorine-containing side chain polyoxyethylene ether glycol-cyclohexyl diisocyanate, the fluorine content is 9%, the solid content is 45%, the viscosity is 1800-2200 mPa s / 25 DEG C, and the structural formula is -[-O-(CH2CH2O) x -CONH-(CH2)6-NHCO-] m -b-[-O-(CH2CH2O) y -CONH-C6H 11 -NHCO-O-CH2CH2CF3-] n - wherein m, n, x and y are number average polymerization degrees, m is an integer ranging from 100 to 140, n is an integer ranging from 20 to 25, x and y are integers ranging from 10 to 15, and -b- represents block copolymerization.

7. A thermally irreversibly color-changing, tamper-evident, transfer adhesive security label according to claim 1, characterized in that: The molecular weight of the polytrifluorochloroethylene resin is 50000-80000, the melting point is 210-215℃, and the fluorine content is 76-78%.

8. A method of manufacturing a heat-activated irreversibly color-changing, tamper-evident, transfer seal, anti-counterfeiting label according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: (1) Pretreatment of the substrate layer: the polyethylene terephthalate film is subjected to corona treatment, and then the surface is wiped with anhydrous ethanol and dried in an oven at 55-60°C for 8-10 min, ready for use; (2) Preparation and coating of the anti-transfer adhesive layer: take two-component solvent-free polyurethane adhesive, fluorine-modified acrylic ester copolymer, and silane coupling agent, add them to a high-speed dispersion machine, and disperse them at a speed of 800-1000 r / min for 30-35 min to mix them evenly; use a comma doctor blade coater to coat the mixed adhesive on the surface of the pretreated substrate layer, and then dry it in an oven at 65-70°C for 12-15 min to form the anti-transfer adhesive layer; (3) Printing of the thermally irreversible color-changing ink layer: first mix the spiropyran microcapsule pigment with deionized water, grind it to a particle size of ≤5 μm using a sand mill, then add fluorine-modified polyurethane resin and fatty alcohol polyoxyethylene ether sodium sulfate, and stir them at a speed of 600-800 r / min for 20-25 min to make the thermally irreversible color-changing ink; Use a flexographic printing machine to print the thermally irreversible color-changing ink on the surface of the anti-transfer adhesive layer, and dry it at 85-90°C for 15-20 min to form the thermally irreversible color-changing ink layer; (4) Preparation and compounding of the surface protective layer: add polytrifluorochloroethylene resin to tetrahydrofuran, and stir it to dissolve at 40°C and a speed of 500 r / min to make a protective layer coating liquid with a solid content of 35-40%; use a curtain coating machine to coat the coating liquid on the surface of the thermally irreversible color-changing ink layer, and then dry it in an oven at 100-105°C for 25-30 min and cool it to room temperature; (5) Post-treatment: cut it into the desired size using a slitting machine, and roll it up to obtain the finished anti-fake label.

9. The manufacturing method of claim 8, wherein: In step (1), the power of the corona treatment is 35-40 W / m 2 , the treatment time is 3-4 s, and the surface tension of the substrate is ≥ 38 mN / m; in step (2), the coating speed is 15-18 m / min, and the doctor blade gap is 0.015 mm.

10. The manufacturing method of claim 8, wherein: In step (3), the grinding medium of the sand mill is zirconia beads with a diameter of 0.8 mm, the grinding speed is 2800 r / min, and the grinding time is 60-90 min; the printing pressure is 0.3-0.4 MPa, and the printing speed is 12-15 m / min; in step (4), the coating speed is 14-16 m / min, and the curtain coating nozzle gap is 0.01 mm.

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