A three-layer anti-counterfeiting label with water-soluble color development, a preparation method thereof and an anti-counterfeiting verification method

Abstract

The present application relates to the technical field of anti-counterfeiting labels, and particularly relates to a three-layer anti-counterfeiting label with color development in water, which comprises, from top to bottom, a thermal paper surface material, an acid-activated colorless dye coating layer coated on the back of the thermal paper surface material; an intermediate layer, the front of which is printed with anti-counterfeiting information, and the front of which is further coated with a local release agent layer, and the back of which is coated with an acid coating layer which is neutral in dry state and releases acidic substances after being dissolved in water; and a bottom paper layer which is combined with the back of the intermediate layer through an adhesive layer; the thermal paper surface material is die-cut to form at least one peelable area and one non-peelable area, the acid-activated colorless dye coating layer and the acid coating layer are respectively arranged in different functional layers, i.e. the back of the surface material and the back of the intermediate layer, and the two layers are physically isolated and do not contact each other in dry state, and the color development reaction is triggered only when water intervenes, dissolves and migrates, so that counterfeiters cannot counterfeit by using simple water color-changing ink, and the anti-counterfeiting level is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of anti-counterfeiting label technology, and in particular to a three-layer anti-counterfeiting label that develops color when soaked in water, its preparation method, and its anti-counterfeiting verification method. Background Technology

[0002] In a market economy, counterfeit and substandard products persist despite repeated crackdowns, severely damaging consumer rights and the brand reputation of genuine manufacturers. Anti-counterfeiting labels, a widely used anti-counterfeiting measure, are affixed to product surfaces or packaging to help consumers and regulatory authorities distinguish genuine products from counterfeits. However, with the continuous upgrading of counterfeiting technology, the anti-counterfeiting capabilities of traditional labels are becoming increasingly insufficient, necessitating the development of new anti-counterfeiting technologies.

[0003] Existing anti-counterfeiting labels mainly adopt the following three technical approaches:

[0004] First, special logos, marks, or QR codes are printed, allowing consumers to scan the code to access the company's query system to verify authenticity. However, the anti-counterfeiting information in this technology is completely digital. Once the QR code is copied, counterfeiters can mass-produce counterfeits, greatly reducing the anti-counterfeiting effect.

[0005] Secondly, there are water-sensitive color-changing ink anti-counterfeiting layers. These labels have ink that changes color upon contact with water printed in specific areas. Authenticity can be determined by observing the color change when water is dropped on the label. For example, Chinese patent application CN1562647A discloses an anti-counterfeiting label structure including a base layer, a main ink layer, and a partially covered water-sensitive color-changing ink marking layer. Chinese patent application 201710359084 discloses a water-sensitive color-changing code anti-counterfeiting label and its preparation method, where the water-sensitive color-changing layer and the underlying digital information layer work together, verifying authenticity through color change when water is dropped on the label. However, the color-changing mechanism of these water-sensitive anti-counterfeiting labels is direct color change. Counterfeiters can easily replicate them using similar water-sensitive color-changing inks, resulting in a low level of anti-counterfeiting. Furthermore, the color change is often reversible, allowing for reuse.

[0006] Third, local release agents and peelable areas for anti-counterfeiting. Chinese patent application CN200610026892.8 discloses a method for manufacturing anti-counterfeiting labels using a film as the substrate. This method involves locally printing a release agent and laminating a peelable area, allowing consumers to verify authenticity by peeling. However, this technology relies solely on the peeling operation itself for verification, lacking an additional color-development verification mechanism. Its anti-counterfeiting measures are limited and easily counterfeited.

[0007] Furthermore, in the transportation of valuables, especially electronic products, if they are rained on or submerged in water during transit, even if the products themselves are not directly damaged, their transportation environment and protective conditions are adversely affected. Existing anti-counterfeiting labels do not have water detection capabilities and cannot inform consumers or quality inspectors whether the product has encountered adverse environments during transportation. Summary of the Invention

[0008] The purpose of this invention is to provide a three-layer anti-counterfeiting label that develops color when soaked in water, its preparation method, and its anti-counterfeiting verification method, so as to solve the problems mentioned in the background art.

[0009] The technical solution of this invention is: a three-layer anti-counterfeiting label that develops color when soaked in water, comprising layers laminated sequentially from top to bottom.

[0010] The thermal paper face material has a colorless dye coating on the back that turns color when it comes into contact with acid.

[0011] The middle layer has anti-counterfeiting information printed on its front side, and a partial release agent layer is also coated on the front side. The back side is coated with an acidic coating that is neutral in the dry state and releases acidic substances when dissolved in water.

[0012] The base paper layer is laminated to the back of the middle layer via an adhesive layer;

[0013] The thermal paper face material is die-cut to form at least one peelable area and one non-peelable area. When peeled, the release agent layer in the peelable area assists in separating the thermal paper face material from the intermediate layer and allows the acidic substance to come into contact with the colorless dye to develop color. The non-peelable area destroys the label structure when peeled.

[0014] The colorless dye that develops color upon contact with acid is colorless or pale in its natural state, but undergoes an irreversible color-developing reaction upon contact with acidic substances to form a colored pattern.

[0015] Furthermore, the colorless dye coating that develops color upon contact with acid has a dry basis weight of 0.5-2.0 g / m², and the acidic coating has a dry basis weight of 0.3-1.0 g / m²; the release agent layer is applied locally, corresponding to the peelable area of ​​the thermal paper surface, and the coating amount has a dry basis weight of 0.2-0.8 g / m².

[0016] Furthermore, the acidic substances in the acidic coating are encapsulated in microcapsules, and the microcapsule wall material is selected from at least one of gelatin, gum arabic, and urea-formaldehyde resin; after dissolving in water, the acidic substances released by the acidic coating reduce the pH value of the contact area to 3.0-5.5; and the color-reacting response time of the colorless dye coating is that it begins to develop color after immersion in water for 3-10 seconds and completes the color development within 30 seconds.

[0017] Furthermore, the release agent layer is a silicone release agent or a solvent-free UV-curable release agent; the difference in peel force between the peelable and non-peelable areas of the thermal paper surface is at least 3N / 25mm; the adhesive layer is a neutral water-based adhesive with a pH value of 6.5-7.5.

[0018] A method for preparing a three-layer anti-counterfeiting label includes the following steps:

[0019] 1. Provide thermal paper face stock, coat the back of the face stock with a colorless dye coating that develops color in response to acid and dry it, with a dry basis weight of 0.5-2.0 g / m²;

[0020] Second, provide an intermediate layer, print anti-counterfeiting information on the front of the intermediate layer, and coat the front with a partial or full-page release agent layer, with a coating amount of 0.2-0.8 g / m² dry weight.

[0021] Third, an acidic coating is applied to the back of the intermediate layer. The acidic coating is neutral in the dry state and releases acidic substances when dissolved in water. The coating amount is 0.3-1.0 g / m² (dry weight).

[0022] Fourth, the thermal paper surface material from step one and the intermediate layer from step one are bonded together with a neutral water-based adhesive with a pH of 6.5-7.5 to form a composite.

[0023] Fifth, provide silicone-coated backing paper as the backing paper layer, and apply an adhesive layer to the adhesive-coated surface of the backing paper;

[0024] 6. Combine the base paper layer from step 5 with the composite from step 4;

[0025] 7. Die-cut and remove waste, and perform zoned die-cutting on the thermal paper surface to form at least one peelable area and one non-peelable area, wherein the peelable area corresponds to the coating area of ​​the release agent layer.

[0026] Furthermore, in step one, the dry basis weight of the colorless dye coating is 0.5-2.0 g / m²; in step two, the dry basis weight of the release agent layer is 0.2-0.8 g / m²; in step three, the dry basis weight of the acidic coating is 0.3-1.0 g / m²; and in step four, the pH value of the neutral structure water-based adhesive is 6.5-7.5.

[0027] Furthermore, in step three, the acidic substance is first encapsulated in microcapsules and then coated on the back of the intermediate layer. The wall material of the microcapsules is selected from at least one of gelatin, gum arabic, and urea-formaldehyde resin.

[0028] Furthermore, in step one, before coating the back of the thermal paper material with a colorless dye coating, a protective coating liquid is first applied to the surface of the thermal paper material. The protective coating liquid consists of the following components in parts by weight: 30-40 parts silicone acrylic emulsion, 10-15 parts polyvinyl alcohol solution, 5-8 parts zinc stearate emulsion, 2-4 parts aluminum hydroxide powder, 1-3 parts calcium carbonate powder, 2-4 parts high melting point wax emulsion, 1.5-3 parts crosslinking agent, 0.1-0.3 parts defoamer, 0.2-0.5 parts leveling agent, and the balance being deionized water.

[0029] A method for anti-counterfeiting verification using a three-layer anti-counterfeiting label includes the following steps:

[0030] When the anti-counterfeiting label comes into contact with water, using water as a migration medium, it causes the acidic coating on the back of the intermediate layer to release acidic substances, which migrate to the colorless dye coating on the back of the thermal paper surface, resulting in an irreversible color-developing reaction and forming a color pattern; or,

[0031] After the anti-counterfeiting label comes into contact with water, the peelable area is peeled off, and the thermal paper surface material and the intermediate layer are separated at the release agent layer. The color development result triggered by peeling or residual acid is directly observed.

[0032] If a colored pattern appears, it indicates that the anti-counterfeiting label is genuine or that the product to which the label is attached has been exposed to water.

[0033] Furthermore, the water in the water-contact step is liquid water or condensed water in a high-humidity environment; the color-developing pattern begins to appear 3-10 seconds after contact with water, and the color development is completed within 30 seconds, and it remains visible after drying; when attempting to peel off the non-peelable area, the thermal paper surface or intermediate layer undergoes structural damage and cannot be completely separated, thus preventing the label from being transferred as a whole.

[0034] The beneficial effects of this invention are:

[0035] Compared with existing technologies, this invention sets the colorless dye coating and the acid coating that develop color when exposed to acid on different functional layers, namely the back of the face material and the back of the intermediate layer. In the dry state, the two are physically isolated and do not come into contact with each other. The color reaction is only triggered when water is introduced, dissolves and migrates in water, making it impossible for counterfeiters to imitate with simple water-sensitive color-changing ink, thus greatly improving the anti-counterfeiting level.

[0036] The color development reaction of this invention is irreversible. Once the label comes into contact with water, the color pattern will still be retained even after drying. This provides consumers and quality inspectors with an objective historical record of whether the product has been exposed to rain or water during transportation, and is especially suitable for monitoring the transportation environment of electronic products.

[0037] The thermal paper surface material partitioning die-cutting design of the present invention has a peelable area and a non-peelable area coexisting. With the local release agent coating, the surface material and intermediate layer in the non-peelable area are destroyed during peeling, and cannot be completely transferred to other products for reuse, effectively preventing malicious transfer behavior. Detailed Implementation

[0038] The present invention will be further illustrated below with reference to embodiments.

[0039] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

[0040] An example of a water-soluble, color-developing three-layer anti-counterfeiting label includes layers laminated sequentially from top to bottom.

[0041] The thermal paper face material 100 has a colorless dye coating 101 that is acid-sensitive and color-reflective. The colorless dye coating that is acid-sensitive includes at least one colorless leuco dye selected from crystal violet lactone, thermo red, and fluorane dyes.

[0042] The intermediate layer 200 has anti-counterfeiting information 201 printed on its front side, and a partial release agent layer 202 coated on its front side. Its back side is coated with an acidic coating 203 that is neutral in the dry state and releases acidic substances when dissolved in water. The acidic substances in the acidic coating 203 are selected from at least one organic acid selected from tartaric acid, citric acid, malic acid, oxalic acid, and boric acid.

[0043] The backing paper layer 300 is laminated to the back of the intermediate layer 200 via the adhesive layer 301;

[0044] The thermal paper face material 100 is die-cut to form at least one peelable area 102 and one non-peelable area 103. When peeling, the release agent layer 202 assists in separating the thermal paper face material 100 from the intermediate layer 200 and allows the acidic substance to come into contact with the colorless dye to develop color. When peeling, the non-peelable area 103 destroys the label structure.

[0045] Colorless dyes that develop color when exposed to acid are colorless or pale in their natural state. When they come into contact with acidic substances, they undergo a color reaction to form a colored pattern, and this color development is irreversible.

[0046] Under normal dry conditions, the two core substances of the color-developing reaction—the colorless dye on the back of the face material 100 and the acidic substance on the back of the intermediate layer 200—are physically isolated, and the acidic coating 203 itself is neutral, thus the label remains stable and colorless. When water is introduced, it acts as a trigger and migration medium, causing the acidic coating 203 to dissolve and release the acidic substance. The acidic substance migrates through the pores of the intermediate layer 200 to the back of the face material 100, comes into contact with the colorless dye coating 101, and triggers an irreversible chemical reaction, thereby revealing the preset pattern or color. Meanwhile, the label face material 100 is die-cut into a peelable area 102 and a non-peelable area 103. Combined with the release agent layer 202 partially coated on the front side of the intermediate layer 200, differentiated peeling characteristics are achieved: the peelable area 102 has weak adhesion due to the presence of the release agent, and users can easily peel it off to directly observe the color development results triggered by the peeling action or residual moisture / acid stains; the non-peelable area 103 is firmly bonded, and forced peeling will cause structural damage to the face material 100 or the intermediate layer 200.

[0047] Counterfeiters cannot easily imitate it with simple water-sensitive color-changing ink because color development requires the combination of water, acidic substances, and colorless dyes, and the acidic substances are neutral in the dry state.

[0048] Irreversible color development provides objective physical evidence of whether a product has been submerged in water or exposed to high humidity. Even after drying, the traces remain, providing a reliable means for monitoring the transportation environment of valuable electronic products, etc.

[0049] The structural differentiation between the peelable and non-peelable areas ensures that any attempt to completely peel off the label for reuse will damage the non-peelable area, thus effectively preventing the label from being maliciously transferred to counterfeit products.

[0050] In an optional embodiment of the present invention, the dry basis weight of the colorless dye coating that develops color in the presence of acid is 0.5-2.0 g / m², and the dry basis weight of the acidic coating is 0.3-1.0 g / m².

[0051] The dry basis weight of the colorless dye coating 101 (0.5-2.0 g / m²) determines the total amount of dye molecules available for color development. If it is below 0.5 g / m², there will be insufficient dye molecules available for reaction, potentially resulting in unclear patterns and overly pale colors. If it is above 2.0 g / m², it will lead to material waste and increased costs, and an excessively thick coating may affect the flexibility and composite strength of the surface material. The dry basis weight of the acidic coating 203 (0.3-1.0 g / m²) determines the total amount of acidic substances released upon contact with water. This content must be sufficient to lower the pH value of the contact area to the color development threshold required by the colorless dye, typically pH 3.0-5.5, to ensure a sufficient and rapid color development reaction. Too low an acidic coating basis weight will result in insufficient pH reduction and inadequate color development; while too high a basis weight may ensure color development, it may lead to over-acidification, posing a potential corrosion risk to the label substrate or other layers and increasing unnecessary costs.

[0052] By precisely controlling the dry weight range of the two key coatings, the anti-counterfeiting label achieves the best balance between "sensitive color development" and "long-term stability," ensuring that the label can start to develop color within a reasonable time after contact with water. At the same time, it ensures that under dry storage conditions, the appropriate coating thickness will not cause false color development due to slight fluctuations in ambient humidity, significantly improving the label's performance reliability and economy.

[0053] In an optional embodiment of the present invention, the release agent layer 202 is a partial coating, corresponding to the peelable area 102 of the thermal paper surface 100, and the coating amount is 0.2-0.8 g / m².

[0054] Localized coating means that the release agent is only present in specific areas of the label, namely the peelable area subsequently die-cut, rather than the entire front side of the intermediate layer 200. This design is the core of achieving the "partial peel" function. Applying the release agent below the peelable area 102 significantly reduces the adhesion between the thermal paper facestock 100 and the intermediate layer 200 in that area. In the non-peelable area 103 without release agent, the two are firmly bonded by the adhesive layer 301. Controlling the coating amount to 0.2-0.8 g / m² is a key process parameter: below 0.2 g / m², a complete release film may not be formed, resulting in excessively high adhesion in the peelable area, making it difficult for users to peel off; above 0.8 g / m², although the release effect is better, the release agent may bleed or migrate, affecting the adhesion of the non-release areas and increasing costs.

[0055] This embodiment achieves precise control over the label peeling behavior, allowing consumers to easily peel off the peelable area 102 for color verification, providing a user-friendly experience; at the same time, the firm adhesion of the non-peelable area 103 effectively prevents the complete transfer of the label.

[0056] In an optional embodiment of the present invention, the acidic substance in the acidic coating 203 is encapsulated in microcapsules, the microcapsule wall material being selected from at least one of gelatin, gum arabic, and urea-formaldehyde resin; the acidic substance serves as the core material and is encapsulated by a polymer wall material formed from gelatin, gum arabic, etc., forming micron-sized capsules. In a dry, normal storage and use environment, the dense microcapsule wall material effectively blocks the acidic substance from contacting the outside environment, preventing its slow release or migration due to moisture absorption. Only when the label undergoes extensive water immersion, water molecules penetrate and disrupt the microcapsule wall material, causing the internal acidic substance to be released in a concentrated and large quantity, reacting with the colorless dye to develop color. This triggered release mechanism greatly improves the chemical stability of the label in its non-use state. Compared to direct coating of the acidic substance, microencapsulation significantly improves the long-term storage stability of the anti-counterfeiting label. Example data shows that microencapsulation can extend the stable storage period of the label in a high temperature and high humidity environment of 40℃ / 85% RH from 6 months to more than 12 months, effectively avoiding "false color development" or "premature expiration" caused by environmental humidity fluctuations during long-distance transportation or warehouse storage, which is especially important for products that require a longer shelf life.

[0057] In an optional embodiment of the present invention, the acidic substances released by the acidic coating after dissolving in water lower the pH value of the contact area to 3.0-5.5. Furthermore, the color-reacting response time of the colorless dye coating is 3-10 seconds after immersion in water, and color development is completed within 30 seconds. The released acidic substances must bring the pH value of the contact area into this range for the color reaction to start smoothly. If the pH value is higher than 5.5, the dye protonation is incomplete, resulting in a pale or slow color development; if it is lower than 3.0, although color development is faster, it may corrode paper or ink and is not cost-effective. The parameters of this embodiment limit the anti-counterfeiting label to have an excellent user experience. After immersing the label in water, consumers can observe the color change within a few seconds and obtain a complete and clear color development result within half a minute. The process is intuitive and fast. At the same time, the response speed is fast enough to accurately reflect whether the product has undergone immersion sufficient to cause damage, improving the accuracy of the judgment.

[0058] In an optional embodiment of the present invention, the release agent layer 202 is a silicone release agent or a solvent-free UV-curable release agent; the difference in peel force between the peelable area 102 and the non-peelable area 103 of the thermal paper surface material 100 is at least 3N / 25mm; the silicone release agent or the solvent-free UV-curable release agent can form a coating with extremely low surface energy, which hardly adheres to the surface material 100, thereby achieving extremely low peel force in the peelable area 102, while in the non-peelable area 103, since there is no release agent, the surface material 100 is directly and firmly bonded to the intermediate layer 200 through the underlying adhesive layer 301, and the peel force is much higher than that in the peelable area. The difference in peeling force between the peelable area 102 and the non-peelable area 103 ensures that users can easily peel off the peelable area with very little force, while when trying to peel off the non-peelable area, much more force is required, such that the paper substrate of the label will tear and break due to stress concentration before the peeling force is reached. This achieves clear and reliable anti-counterfeiting verification and anti-transfer functions. Any attempt to completely peel off the entire label will cause irreversible damage to the label structure, thereby rendering it worthless and preventing it from being transferred to counterfeit products.

[0059] In an optional embodiment of the present invention, the adhesive layer 301 is a neutral water-based adhesive with a pH value of 6.5-7.5. The adhesive layer 301 is flanked by a colorless dye coating 101 that develops color when exposed to acid and a neutral acidic coating 203 in its dry state, respectively. If the adhesive layer 301 itself is acidic, acidic substances may slowly migrate or penetrate into the colorless dye coating 101 during long-term direct contact, causing the label to exhibit unexpected "false color development" during storage and prematurely fail. Conversely, if it is alkaline, it may neutralize acidic substances released upon contact with water, weakening or destroying the color development effect after immersion in water. The use of a neutral adhesive eliminates the chemical interference of the adhesive itself on the anti-counterfeiting color development mechanism, ensuring that the face material 100 and the intermediate layer 200 are physically firmly bonded while maintaining a chemically isolated and stable state. This provides a crucial guarantee for the long-term storage stability of the label and is an important technical detail ensuring the integrity of the anti-counterfeiting function throughout the product's entire lifecycle from manufacturing to use.

[0060] A method for preparing a three-layer anti-counterfeiting label includes the following steps:

[0061] 1. Provide thermal paper face stock 100, coat the back of the face stock with a colorless dye coating 101 that develops color when exposed to acid and dry it, with a dry basis weight of 0.5-2.0 g / m²;

[0062] Second, an intermediate layer 200 is provided, on which anti-counterfeiting information 201 is printed, and a partial or full-page release agent layer 202 is coated on the front, with a coating amount of 0.2-0.8 g / m².

[0063] Third, an acidic coating 203 is applied to the back of the intermediate layer 200. The acidic coating is neutral in the dry state and releases acidic substances after dissolving in water. The coating amount is 0.3-1.0 g / m² (dry weight).

[0064] Fourth, the thermal paper surface material 100 from step one and the intermediate layer 200 from step c are bonded together with a neutral water-based adhesive with a pH of 6.5-7.5 to form a composite.

[0065] Fifth, a silicone-coated backing paper is provided as the backing paper layer 300, and an adhesive layer 301 is applied to the adhesive-coated surface of the backing paper;

[0066] 6. Composite the base paper layer 300 from step 5 with the composite from step 4;

[0067] 7. Die-cut and remove waste, and perform zoned die-cutting on the thermal paper surface 100 to form at least one peelable area 102 and one non-peelable area 103, wherein the peelable area 102 corresponds to the coating area of ​​the release agent layer 202.

[0068] In an optional embodiment of the present invention, in step three, the acidic substance is first encapsulated in a microcapsule and then coated on the back side of the intermediate layer. The wall material of the microcapsule is selected from at least one of gelatin, gum arabic, and urea-formaldehyde resin.

[0069] In an optional embodiment of the present invention, in step one, before coating the back of the thermal paper material with a colorless dye coating, a protective coating liquid is first coated on the surface of the thermal paper material. The protective coating liquid is composed of the following components in parts by weight: 30-40 parts of silicone acrylic emulsion, 10-15 parts of polyvinyl alcohol solution, 5-8 parts of zinc stearate emulsion, 2-4 parts of aluminum hydroxide powder, 1-3 parts of calcium carbonate powder, 2-4 parts of high melting point wax emulsion, 1.5-3 parts of crosslinking agent, 0.1-0.3 parts of defoamer, 0.2-0.5 parts of leveling agent, and the balance being deionized water.

[0070] A method for anti-counterfeiting verification using a three-layer anti-counterfeiting label includes the following steps:

[0071] When the anti-counterfeiting label comes into contact with water, water acts as a migration medium, causing the acidic coating 203 on the back of the intermediate layer 200 to release acidic substances, which migrate to the colorless dye coating 101 on the back of the thermal paper surface 100, resulting in an irreversible color-developing reaction and forming a color pattern; or,

[0072] After the anti-counterfeiting label comes into contact with water, the peelable area 102 is peeled off, so that the thermal paper surface material 100 and the intermediate layer 200 are separated at the release agent layer 202, and the color development result stimulated by peeling or residual acid is directly observed.

[0073] If a colored pattern appears, it indicates that the anti-counterfeiting label is genuine or that the product to which the label is attached has been exposed to water.

[0074] In an optional embodiment of the present invention, the water in the water-contact step is liquid water or condensed water in a high-humidity environment; the color-developing pattern begins to appear 3-10 seconds after contact with water, and the color development is completed within 30 seconds, and remains visible after drying; when attempting to peel off the non-peelable area 103, the thermal paper surface 100 or the intermediate layer 200 suffers structural damage and cannot be completely separated, so as to prevent the label from being transferred as a whole.

[0075] Example 1

[0076] 1. Pretreatment of thermal paper surface material

[0077] A thermal paper with a basis weight of 80 g / m² was used as the face stock. A colorless dye coating that develops color in acid was applied to the back of the face stock using a gravure coating process. The coating formulation was: 10 parts by weight of crystal violet lactone, 15 parts by weight of polyvinyl alcohol, 0.2 parts by weight of defoamer, 0.3 parts by weight of leveling agent, and 74.5 parts by weight of deionized water. The dry basis weight of the coating was 1.0 g / m², and the coating was dried at 80℃ after application.

[0078] Second, the processing of the intermediate layer.

[0079] A 23μm thick PET film was used as the intermediate layer substrate. Anti-counterfeiting information, including a QR code and company logo, was printed on the front side of the intermediate layer using flexographic printing. After printing, a silicone release agent was applied to a localized area on the front side, corresponding to the "peelable area" for subsequent die-cutting. The dry weight of the release agent was 0.5 g / m², and the mixture was cured at 100℃ for 30 seconds.

[0080] An acidic coating was applied to the back of the intermediate layer using a doctor blade coating method. Citric acid was selected as the acidic substance and was mixed with a neutral aqueous carrier at a mass ratio of 1:4. The dry weight of the coating was 0.6 g / m². After coating, it was dried at 80°C. The pH value of the acidic coating was 6.8 in the dry state, and the pH value dropped to about 4.0 after dissolving in water.

[0081] Third, composite and die-cutting

[0082] The thermal paper surface material treated in step one and the intermediate layer treated in step two are laminated together using a neutral structure water-based adhesive. The lamination pressure is 0.3 MPa and the lamination temperature is room temperature.

[0083] Silicone-coated backing paper with a basis weight of 60 g / m² is provided. A water-based acrylic adhesive is coated on the adhesive-coated surface of the backing paper. After being laminated with the above-mentioned composite, the paper is die-cut and waste is removed by a die-cutting machine. The thermal paper face material is then divided into two sections for die-cutting, forming one peelable area and one non-peelable area, resulting in the finished anti-counterfeiting label.

[0084] IV. Performance Testing

[0085] The finished label was immersed in deionized water for 30 seconds, and the color development was observed. Test results showed that a purple color began to appear on the back of the substrate after approximately 8 seconds of immersion, and the color was fully developed after 30 seconds, with a clear and complete pattern. After the label was removed and dried, the color pattern remained unchanged, without fading. Simultaneously, the peelable area could be easily peeled off by hand with a peel force of approximately 1.2 N / 25 mm. After peeling, the acid stains on the corresponding area on the back of the substrate and the middle layer were clearly distinguishable. Forcibly peeling the non-peelable area resulted in tearing of the substrate and damage to the label structure, making complete removal impossible. After being stored at 40℃ and 85% RH for 6 months, the label showed no significant performance degradation.

[0086] Example 2

[0087] I. Preparation of microcapsules for acidic substances

[0088] Dissolve 20g of gelatin in 500mL of deionized water and heat to 50℃ while stirring until completely dissolved. Separately, dissolve 20g of gum arabic in 500mL of deionized water and heat to 50℃ as well. Mix the two solutions and stir well. Add 30g of citric acid as the core material. Adjust the pH of the system to 4.0-4.2 with 10% acetic acid. Continue stirring for 30 minutes to allow the gelatin and gum arabic to form a complex condensed phase that coats the core material through electrostatic adsorption. Cool the system to below 10℃ and add 5mL of glutaraldehyde (25% aqueous solution) as a crosslinking agent. Curing treatment is performed for 2 hours. Filter and collect the microcapsules, wash three times with deionized water, and vacuum dry at 40℃ to obtain citric acid microcapsules with an average particle size of 5μm.

[0089] II. Label Preparation

[0090] The label was prepared according to the steps of Example 1, except that the acid coating was applied using the citric acid microcapsules prepared above instead of free citric acid. The microcapsules and the neutral carrier were compounded at a mass ratio of 1:1, and the dry weight of the coating was 0.8 g / m².

[0091] III. Performance Testing

[0092] Finished labels were subjected to routine storage stability tests and water-induced color development tests. Routine storage stability test: After storing the labels at 40℃ and 85% RH for 12 months, no color development was observed on the back of the label, indicating that microencapsulation effectively prevented premature leakage of acidic substances and color development reactions. Water-induced color development test: The labels were immersed in deionized water. After approximately 10 seconds, the microcapsule walls began to swell and rupture, releasing citric acid. A purple color appeared on the back of the label after approximately 12 seconds, and the color development was complete and clear after approximately 28 seconds. Compared to Example 1, the color development response of the microencapsulation scheme was slightly delayed, increasing by approximately 2-4 seconds, but the storage stability was significantly improved, from 6 months to over 12 months, indicating that microencapsulation treatment has a significant advantage in terms of storage stability.

[0093] Example 3

[0094] 1. Preparation of protective coating liquid

[0095] Prepare the protective coating solution according to the following parts by weight: 35 parts silicone-acrylic emulsion (45% solid content), 12 parts polyvinyl alcohol solution (PVA2588 type, 10%), 6 parts zinc stearate emulsion (40% solid content), 3 parts aluminum hydroxide powder (average particle size 2μm), 2 parts calcium carbonate powder (average particle size 1.5μm), 3 parts high melting point wax emulsion (30% solid content), 2 parts epoxy-modified aziridine crosslinking agent, 0.2 parts defoamer, 0.3 parts leveling agent, and 36.5 parts deionized water. Add each component sequentially and disperse at high speed for 30 minutes until homogeneous.

[0096] 2. Coating of the protective layer

[0097] The protective coating liquid is applied to the front side of the thermal paper material, i.e. the thermal color-developing side, using a gravure coating method. The dry weight of the coating is 1.0 g / m². After coating, it is dried and crosslinked at 100°C for 1 minute.

[0098] III. Label Preparation

[0099] The remaining steps are performed according to Example 2.

[0100] IV. Performance Testing

[0101] Thermal printing tests were conducted on the protective layer surface. Print clarity was good, and there was no adhesion or trailing on the protective layer surface after printing. Water wiping test: The thermal printing area was wiped 10 times with a damp cotton swab; no significant wear or fading was observed in the printed content. Water resistance test: The label was immersed in deionized water for 30 minutes; after removal, both the thermal printing area and the anti-counterfeiting color-developing area remained intact. Compared to the control group without a protective layer, the surface friction coefficient of the label decreased from 0.55 to 0.28 after coating with the protective layer, significantly improving slip resistance and the smoothness of paper feeding during printing.

[0102] Comparative Example 1

[0103] The anti-counterfeiting label was prepared according to the steps of Example 1, except that no release agent layer was applied, and the middle layer was directly laminated to the face material after only anti-counterfeiting information was printed on the front. Test results showed that there was no significant difference in peel force between the peelable and non-peelable areas, both being approximately 5.0 N / 25 mm. Consumers could not easily peel off the peelable area to verify the color development, indicating that the peel verification function of the anti-counterfeiting label was missing.

[0104] Comparative Example 2

[0105] The anti-counterfeiting label was prepared according to the steps of Example 1, except that citric acid and crystal violet lactone were mixed and simultaneously coated on the back of the thermal paper material, with a dry basis weight of 1.6 g / m². Test results showed that the label exhibited a noticeable purple color immediately after preparation, and the color development failed before leaving the factory. This indicates that the acidic substance and the colorless dye could not effectively isolate the color development reaction when coated in the same layer, rendering the label impractical.

[0106] Summary of key performance data

[0107] Color development response time (seconds) It takes about 8 seconds to develop the color, and 30 seconds for it to fully develop. It takes about 10 seconds to develop the color, and 28 seconds for it to fully develop. It takes about 10 seconds to develop the color, and 28 seconds for it to fully develop. It takes about 8 seconds to develop the color, and 30 seconds for it to fully develop. Color develops immediately after preparation Color clarity Clear and complete Clear and complete Clear and complete Clear and complete — Color development is irreversible Irreversible Irreversible Irreversible Irreversible — Peeling force in the peelable area (N / 25mm) Approximately 1.2 Approximately 1.2 Approximately 1.2 Approximately 5.0 — Peeling force in non-peelable areas (N / 25mm) >5.0 >5.0 >5.0 Approximately 5.0 — Storage stability (40℃ / 85% RH) ≥6 months ≥12 months ≥12 months ≥6 months Preparation is the only way to make it fail. Coefficient of friction of protective layer surface not applicable not applicable 0.28 0.55 not applicable Water resistance of protective layer not applicable not applicable pass not applicable not applicable

[0108] As shown in the table above, all embodiments of the present invention achieve the technical effects of water-reactive color development, dual verification, irreversible recording, and prevention of secondary transfer. Embodiment 2 significantly improved the storage stability of the label through microencapsulation, while Embodiment 3 further improved the surface smoothness and water resistance of the label through protective coating. A comparison of Embodiments 1-3 with Comparative Example 1 shows that localized coating of the release agent layer is key to achieving a difference in peel force between the peelable and non-peelable areas. A comparison of Embodiments 1-3 with Comparative Example 2 shows that having acidic substances and colorless dyes in different functional layers is a necessary condition for long-term stable storage under dry conditions.

[0109] The water-soluble color-developing three-layer anti-counterfeiting label of this invention can be industrially produced using conventional coating, printing, laminating, and die-cutting equipment. The process is mature, raw materials are widely available, and production costs are controllable, making it highly practical for industrial applications. This anti-counterfeiting label can be widely used in fields requiring anti-counterfeiting protection and environmental sensitivity, such as electronic products, precision instruments, pharmaceuticals, alcoholic beverages, and cosmetics. It can also be used to detect and record whether goods have experienced adverse environmental conditions during logistics and transportation.

[0110] In the description of this specification, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship, are only for the convenience of describing the technical solution of this patent and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this patent application.

[0111] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this patent application, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0112] In this specification, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this specification according to the specific circumstances.

[0113] In this specification, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0114] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A three-layer anti-counterfeiting label that develops color when soaked in water, characterized in that: Including composites from top to bottom The thermal paper face material (100) has a colorless dye coating (101) on its back side that shows color when exposed to acid. The intermediate layer (200) has anti-counterfeiting information printed on its front side (201) and a partial release agent layer (202) coated on its front side, and an acidic coating (203) coated on its back side, which is neutral in the dry state and releases acidic substances when dissolved in water. The backing paper layer (300) is laminated to the back of the intermediate layer (200) via an adhesive layer (301); The thermal paper material (100) is die-cut to form at least one peelable area (102) and one non-peelable area (103). When peeled, the release agent layer (202) in the peelable area (102) assists in separating the thermal paper material (100) from the intermediate layer (200) and allows the acidic substance to come into contact with the colorless dye to develop color. The non-peelable area (103) destroys the label structure when peeled. The colorless dye that develops color upon contact with acid is colorless or pale in its natural state, but undergoes an irreversible color-developing reaction upon contact with acidic substances to form a colored pattern.

2. The three-layer anti-counterfeiting label according to claim 1, characterized in that: The dry basis weight of the colorless dye coating that develops color in the presence of acid is 0.5-2.0 g / m², and the dry basis weight of the acidic coating is 0.3-1.0 g / m²; the release agent layer (202) is a partial coating, corresponding to the peelable area (102) of the thermal paper surface material (100), and the coating amount is 0.2-0.8 g / m².

3. The three-layer anti-counterfeiting label according to claim 1, characterized in that: The acidic substances in the acidic coating (203) are encapsulated in microcapsules, and the wall material of the microcapsules is selected from at least one of gelatin, gum arabic, and urea-formaldehyde resin. After dissolving in water, the acidic substances released by the acidic coating reduce the pH value of the contact area to 3.0-5.

5. Furthermore, the color-reacting response time of the colorless dye coating is that it begins to develop color after immersion in water for 3-10 seconds and completes the color development within 30 seconds.

4. The three-layer anti-counterfeiting label according to claim 1, characterized in that: The release agent layer (202) is an organosilicon release agent or a solvent-free UV-curable release agent; the difference in peel force between the peelable area (102) and the non-peelable area (103) of the thermal paper surface material (100) is at least 3N / 25mm; the adhesive layer (301) is a neutral structure water adhesive with a pH value of 6.5-7.

5.

5. A method for preparing a three-layer anti-counterfeiting label according to any one of claims 1 to 4, characterized in that: Includes the following steps 1. Provide a thermal paper face stock (100), coat the back of the face stock with a colorless dye coating (101) that develops color when exposed to acid and dry it, with a dry basis weight of 0.5-2.0 g / m²; Second, an intermediate layer (200) is provided, anti-counterfeiting information (201) is printed on the front of the intermediate layer, and a partial or full-page release agent layer (202) is coated on the front, with a coating amount of 0.2-0.8 g / m². Third, an acidic coating (203) is applied to the back of the intermediate layer (200). The acidic coating is neutral in the dry state and releases acidic substances after dissolving in water. The coating amount is 0.3-1.0 g / m² dry weight. Fourth, the thermal paper surface material (100) from step one and the intermediate layer (200) from step (c) are bonded together with a neutral water-based adhesive with a pH of 6.5-7.5 to form a composite. Fifth, a silicone-coated backing paper is provided as a backing paper layer (300), and an adhesive layer (301) is applied to the adhesive-coated surface of the backing paper.

6. Combine the base paper layer (300) from step 5 with the composite from step 4; 7. Die-cut waste removal and perform partitioned die-cutting on the thermal paper surface material (100) to form at least one peelable area (102) and one non-peelable area (103), wherein the peelable area (102) corresponds to the coating area of ​​the release agent layer (202).

6. The preparation method according to claim 5, characterized in that: In step one, the dry basis weight of the colorless dye coating (101) is 0.5-2.0 g / m²; in step two, the dry basis weight of the release agent layer (202) is 0.2-0.8 g / m²; in step three, the dry basis weight of the acidic coating (203) is 0.3-1.0 g / m²; in step four, the pH value of the neutral structure water-based adhesive is 6.5-7.

5.

7. The preparation method according to claim 5, characterized in that: In step three, the acidic substance is first encapsulated in microcapsules and then coated on the back of the intermediate layer. The wall material of the microcapsules is selected from at least one of gelatin, gum arabic, and urea-formaldehyde resin.

8. The preparation method according to claim 5, characterized in that: In step one, before coating the back of the thermal paper with a colorless dye coating, a protective coating liquid is first applied to the surface of the thermal paper. The protective coating liquid consists of the following components in parts by weight: 30-40 parts silicone acrylic emulsion, 10-15 parts polyvinyl alcohol solution, 5-8 parts zinc stearate emulsion, 2-4 parts aluminum hydroxide powder, 1-3 parts calcium carbonate powder, 2-4 parts high melting point wax emulsion, 1.5-3 parts crosslinking agent, 0.1-0.3 parts defoamer, 0.2-0.5 parts leveling agent, and the balance being deionized water.

9. A method for anti-counterfeiting verification using a three-layer anti-counterfeiting label as described in any one of claims 1 to 4, characterized in that: Includes the following steps, When the anti-counterfeiting label comes into contact with water, water acts as a migration medium, causing the acidic coating (203) on the back of the intermediate layer (200) to release acidic substances and migrate to the colorless dye coating (101) on the back of the thermal paper material (100), resulting in an irreversible color reaction and forming a color pattern. or, After the anti-counterfeiting label comes into contact with water, the peelable area (102) is peeled off, so that the thermal paper surface material (100) and the intermediate layer (200) are separated at the release agent layer (202), and the color development result stimulated by peeling or residual acid is directly observed. If a colored pattern appears, it indicates that the anti-counterfeiting label is genuine or that the product to which the label is attached has been exposed to water.

10. The anti-counterfeiting verification method according to claim 9, characterized in that: The water in the water-contact step is liquid water or condensed water in a high-humidity environment; the color-developing pattern begins to appear 3-10 seconds after contact with water, and the color development is completed within 30 seconds, and it remains visible after drying; when attempting to peel off the non-peelable area (103), the thermal paper surface material (100) or the intermediate layer (200) suffers structural damage and cannot be completely separated, so as to prevent the label from being transferred as a whole.