A patterned encryption method and anti-counterfeiting label combining room temperature phosphorescence and ultraviolet laser marking

Abstract

A patterned encryption method and anti-counterfeiting label combining room temperature phosphorescence and ultraviolet laser marking, wherein the patterned encryption method comprises: dispersing a room temperature phosphorescent material in deionized water, and adding a water-soluble fluorescent dye to form a mixed solution; coating the obtained mixed solution on a substrate, volatilizing the solvent to form a phosphorescent film on the substrate; then using water vapor to act on the phosphorescent film to completely quench the phosphorescence; importing a preset encryption pattern into an ultraviolet laser marking machine, and generating the encryption pattern on the phosphorescent film through a marking operation. The encryption technology provided by the present invention can realize patterning simply and quickly, and the acquisition conditions of the pattern are simple, and it only needs to export the picture, and the encryption technology level is high, and it can only be decrypted under specific external conditions. The encryption technology is applicable to many substrates, specifically including glass substrates, PET substrates, etc., and can be used on devices as well as for convenient labels.

Description

Technical Field

[0001] The present invention relates to the technical field of optical information encryption, and in particular to a patterned encryption method and an anti-counterfeiting label combining room temperature phosphorescence with ultraviolet laser marking. Background Art

[0002] Organic room-temperature phosphorescent materials based on polymer matrices have potential application prospects in advanced anti-counterfeiting, data encryption and decryption, optoelectronics, molecular sensors and bioimaging due to their environmental friendliness, simple processing and readily available materials.

[0003] Ultraviolet laser marking technology uses a high-energy ultraviolet laser beam to process the surface of an object, breaking chemical bonds within the material or surrounding medium, thereby marking the surface. However, this visible mark is not conducive to information encryption and is therefore currently rarely used in the field.

[0004] Ultraviolet laser marking mainly uses a cold light source with a wavelength of 355nm. It belongs to the field of cold processing. The processing heat impact is smaller than that of fiber laser marking. The minimum focused spot can reach 10μm and the line spacing can reach 0.04mm. It can perform fine marking and achieve small-scale patterning and encryption.

[0005] Patent publication number CN 111662704 A discloses a method for preparing a novel organic phosphorescent material and its application in inkjet printing inks and writing inks. Currently, inkjet printing technology is widely used in the field of room-temperature phosphorescent encryption. However, commercial inkjet printers are limited in their compatibility with substrates, primarily commercial A4 paper and filter paper. Furthermore, the substrates require certain pretreatment, making them relatively complex to use and lacking in sophistication. Furthermore, erasing an existing pattern with inkjet printing is difficult or requires complex erasure conditions, and reprinting a new pattern is difficult. Summary of the Invention

[0006] Based on this, the present invention provides a pattern encryption method combining room temperature phosphorescence with ultraviolet laser marking to solve the technical problem of how to achieve pattern encryption by combining room temperature phosphorescence with ultraviolet laser marking.

[0007] To achieve the above object, the present invention provides a pattern encryption method combining room temperature phosphorescence and ultraviolet laser marking, which comprises the following steps:

[0008] S1, a room temperature phosphorescent material having an ultraviolet absorption wavelength of 240nm to 340nm, capable of quenching phosphorescence by water absorption and recovering phosphorescence by heat, and a Foster The water-soluble fluorescent dye of the resonance energy transfer acceptor is dispersed in deionized water, wherein the concentration of the room temperature phosphorescent material is 25 mg / mL to 75 mg / mL, and the doping amount of the water-soluble fluorescent dye is 0 to 0.4 wt %;

[0009] S2, coating the mixed solution obtained in step S2 on a substrate, volatilizing the solvent to form a phosphorescent film on the substrate; then applying water vapor at 35-80° C. to the phosphorescent film to completely quench the phosphorescence;

[0010] S3. Import a preset encryption pattern into the UV laser marking machine, and generate the encryption pattern on the phosphor film through a marking operation.

[0011] As a further preferred embodiment of the present invention, the room temperature phosphorescent material is a copolymer obtained by polymerization of acrylamide and 4-(4-vinylphenyl)pyridine having the following structure:

[0012]

[0013] Among them, the ratio of m to n is 1:100 to 1:1000.

[0014] The preparation method of the copolymer is as follows:

[0015] 0.00180 g of 4-(4-vinylphenyl)pyridine, 0.71009 g of acrylamide, and 0.01640 g of azobisisobutyronitrile were dissolved in 5 ml of N,N-dimethylformamide. The mixture was evacuated and replaced with nitrogen three times, and the reaction was carried out at 70°C for 24 hours. After the reaction, the crude solid product was filtered, dialyzed against deionized water, and freeze-dried to obtain a solid block product, which is the copolymer with the above structural formula. The main phosphorescence emission peak is located at approximately 463 nm, the phosphorescence lifetime is 1459.5 ms, and the phosphorescence quantum yield is 22.33%.

[0016] As a further preferred technical solution of the present invention, the water-soluble fluorescent dye is rhodamine B.

[0017] As a further preferred technical solution of the present invention, the parameter ranges of the ultraviolet laser marking are: marking rate of 5 mm / s to 25 mm / s, marking power of 10% to 50%, and marking frequency of 60 kHz to 100 kHz.

[0018] As a further preferred technical solution of the present invention, the image format of the encrypted pattern introduced by the ultraviolet laser marking is a grayscale image.

[0019] As a further preferred technical solution of the present invention, the encryption pattern is a QR code or a barcode.

[0020] As a further preferred technical solution of the present invention, the substrate is a glass substrate or a self-adhesive PET label sticker.

[0021] As a further preferred technical solution of the present invention, before step S2, the following steps are also included: a metal sheet is adhered to the other side of the substrate for forming the phosphorescent film, and the substrate is made of a transparent material; another preset encryption pattern that is different from the encryption pattern of step S3 is introduced into the ultraviolet laser marking machine, and through the marking operation, the encryption pattern is etched on the substrate through the metal sheet, and the encryption pattern on the substrate overlaps with the encryption pattern generated on the phosphorescent film in step S3.

[0022] According to another aspect of the present invention, the present invention further provides an anti-counterfeiting label, which adopts the patterned encryption method combining the above-mentioned room temperature phosphorescence and ultraviolet laser marking.

[0023] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0024] 1) The encryption technology provided by the present invention does not need to pay special attention to the condition of the substrate. It only needs to be coated on the substrate and formed into a film. It is simple to operate, practical, easy to produce and prepare, and low in cost.

[0025] 2) The encryption technology provided by the present invention can realize patterning simply and quickly, and the conditions for obtaining the pattern are simple, and it only requires exporting the picture.

[0026] 3) The encryption technology provided by the present invention is of a higher level and can be decrypted only under specific external conditions.

[0027] 4) The encryption technology provided by the present invention is applicable to many substrates, including glass substrates, PET substrates, etc., and can be used not only on devices but also on convenient labels;

[0028] 5) The patterning technology provided by the present invention has a high degree of precision, with a minimum line width of up to 10 μm, and can be easily erased and re-patterned repeatedly. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Figure 1 Schematic diagram of the solid pattern in Example 1 of the present invention under daylight and dark conditions, under 254nm ultraviolet irradiation, and after removal, wherein a, b, and c are performed under daylight conditions, respectively, and d and e are performed under dark conditions, respectively;

[0031] Figure 2Schematic diagram of the solid pattern in Example 2 of the present invention under daylight and dark conditions, under 254nm ultraviolet irradiation, and after removal, wherein a, b, and c are performed under daylight conditions, respectively, and d and e are performed under dark conditions, respectively;

[0032] Figure 3 Schematic diagram of two solid patterns in Example 3 of the present invention under 254nm ultraviolet irradiation under daylight and dark conditions and after removal, where a, b, and c are performed under daylight conditions, respectively, and d and e are performed under dark conditions, respectively;

[0033] Figure 4 Schematic diagrams of the physical pattern under 254nm UV irradiation and removal under daylight and dark conditions, as well as a schematic diagram of affixing a label to an object in Example 4 of the present invention, where a, b, c, and f are performed under daylight conditions, respectively, and d, e, g, and h are performed under dark conditions, respectively;

[0034] Figure 5 Schematic diagram of erasing a solid pattern by exhalation and replacing it with a different QR code pattern in Example 5 of the present invention, all performed in dark conditions;

[0035] Figure 6 The graph is a UV-visible absorption spectrum corresponding to the copolymer of the present invention, UV laser, and Rhodamine B.

[0036] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0037] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0038] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which this invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are conventional biochemical reagents; the experimental methods described, unless otherwise specified, are conventional methods.

[0039] The patterned encryption method of the present invention combines room temperature phosphorescence with ultraviolet laser marking. First, by selecting phosphorescent molecular materials with a low number of π electrons, the fewer the number of π electrons, the more blue-shifted the ultraviolet absorption of the phosphorescent molecules is, which is about 240nm to 340nm, and the wavelength of the ultraviolet laser is 355nm. Therefore, the absorption of the ultraviolet laser by the phosphorescent molecules is very weak, so they are not etched away, and there will be no pattern visible to the naked eye. In comparison, water-soluble fluorescent dyes have strong absorption of 355nm ultraviolet lasers and can be etched away during the marking process. However, the doping amount of the fluorescent dye is extremely small. By adjusting the appropriate power, the etched fluorescent dye can be made to leave no clearly visible pattern. For specific ultraviolet-visible light absorption conditions, refer to Figure 6 . Secondly, as a high-energy laser beam, ultraviolet laser can not only etch patterns at a fixed point, but also serve as a heating source to heat the position where the laser passes, so that the position that has been quenched by water can restore phosphorescence, and then present the corresponding encrypted pattern under ultraviolet irradiation. In order to make information encryption more intuitive, the phosphorescent material used in the present invention has a longer phosphorescence lifetime and a higher phosphorescence quantum yield, and adopts a combination of phosphorescence encryption and digital encryption, so that the encrypted information needs to be read with relevant digital information decryption equipment. The encrypted information reading equipment belongs to the existing conventional technology and will not be described here.

[0040] The room temperature phosphorescent materials used in the following examples are all copolymers having the following structure:

[0041]

[0042] Among them, the ratio of m to n is 1:100 to 1:1000.

[0043] This copolymer can be obtained by polymerizing acrylamide with 4-(4-vinylphenyl)pyridine. The preparation method thereof belongs to the prior art and is not described in detail here. Of course, the room temperature phosphorescent material used in the present invention for patterned encryption in combination with ultraviolet laser marking can also be other types, as long as the ultraviolet absorption wavelength is between 240nm and 340nm and the room temperature phosphorescent material can be water-quenched and thermally restored to phosphorescence.

[0044] Example 1

[0045] This embodiment proposes a pattern encryption method combining room temperature phosphorescence and ultraviolet laser marking, and the specific steps are as follows:

[0046] Weigh 150mg of the copolymer into a 10ml centrifuge tube and dissolve it in 3ml of deionized water. Ultrasonicate the copolymer in an ultrasonic cleaner for 20 minutes to evenly disperse it. After cooling to room temperature, apply the coating to a cleaned glass substrate and dry it on an 80°C hot plate for 15-20 minutes to completely remove the moisture, forming a phosphorescent film. Then, fumigate the marked area with 60°C water to completely quench the phosphorescence.

[0047] The generated QR code image is imported into the laser marking machine, and the laser marking speed is adjusted to 5mm / s, the power to 25%, and the frequency to 80kHz. Finally, the QR code is printed on the phosphorescent film using the set parameters to obtain the anti-counterfeiting label.

[0048] The results obtained refer to Figure 1 , the UV laser heats the position of the QR code pattern at a fixed point, so that the phosphorescence of the hit position is restored. The resulting QR code is invisible to the naked eye under sunlight (see Figure 1 a); in sunlight or in darkness, and at the same time under 254nm UV irradiation (see Figure 1 b and d) or remove irradiation (see Figure 1 After c) and e), the QR code can be seen and the information can be scanned, thus achieving the effect of anti-counterfeiting and encryption.

[0049] Example 2

[0050] The difference between this embodiment and embodiment 1 is that the coating solution is further doped with the fluorescent dye Rhodamine B.

[0051] Weigh 3 mg of rhodamine B into a 10 mL centrifuge tube and add 6 mL of deionized water to dissolve it to prepare a 0.5 mg / mL rhodamine B solution.

[0052] Weigh 150mg of the copolymer into a 10mL centrifuge tube, add 600µL of the Rhodamine B solution, and then add 2400µL of deionized water. Ultrasonicate the solution in an ultrasonic cleaner for 20 minutes to evenly disperse the copolymer and thoroughly mix it with the Rhodamine B. After cooling to room temperature, apply 400µL of the solution to a cleaned glass substrate and dry it on an 80°C hot plate for 15-20 minutes to completely remove the moisture, forming a phosphorescent film. Then, fumigate the marked area with 60°C water to completely quench the phosphorescence.

[0053] The generated QR code image is imported into the laser marking machine, and the laser marking speed is adjusted to 10mm / s, the power to 25%, and the frequency to 80kHz. Finally, the QR code is printed on the phosphorescent film using the set parameters to obtain the anti-counterfeiting label.

[0054] The results obtained refer to Figure 2In addition to heating the QR code pattern at a fixed point and restoring phosphorescence, the UV laser also partially removes the fluorescent dye. Therefore, the resulting QR code is difficult to identify with the naked eye under sunlight (see Figure 2 At the same time, due to the interference of background fluorescence of fluorescent dyes, the QR code cannot be scanned under 254nm UV irradiation (see b and d in the figure); in daylight or darkness, at the same time, under 254nm UV removal irradiation (see Figure 2 After c) and e), the QR code can be seen and the information can be scanned, thus achieving the effect of anti-counterfeiting and encryption.

[0055] In addition, through the Förster resonance energy transfer mechanism, doping with fluorescent dyes can not only enhance background fluorescence interference, but also produce a two-dimensional code with a pink and white color. Depending on the doping concentration and the fluorescent dye, two-dimensional codes of other colors can also be obtained.

[0056] Example 3

[0057] The difference between this embodiment and embodiment 1 is that the glass substrate and the phosphorescent film are respectively marked with a QR code.

[0058] The first generated QR code image was loaded into a laser marking machine. The laser marking speed was adjusted to 5 mm / s, the power to 40%, and the frequency to 80 kHz. A bright black aluminum sheet with strong UV absorption (40% power can produce a clear pattern) was placed underneath the glass substrate and overlaid. After UV laser treatment, the QR code was etched onto the glass substrate through the bright black aluminum sheet. The resulting QR code on the glass substrate was visible to the naked eye in sunlight but difficult to discern in the dark.

[0059] Weigh 150mg of the copolymer into a 10ml centrifuge tube and dissolve it in 3ml of deionized water. Ultrasonicate the copolymer in an ultrasonic cleaner for 20 minutes to evenly disperse it. After cooling to room temperature, apply it to the top surface of a cleaned glass substrate and dry it on an 80°C hot plate for 15-20 minutes to completely remove the moisture, forming a phosphorescent film. Then, fumigate with 60°C water until the phosphorescence at the marked area is completely quenched.

[0060] The generated second QR code image is imported into the laser marking machine, and the laser marking speed is adjusted to 5mm / s, the power to 25%, and the frequency to 80kHz. Finally, the second QR code is printed on the phosphorescent film using the set parameters, resulting in a double-encrypted anti-counterfeiting label.

[0061] In the above operation: the first QR code is a QR code of false information, which cannot be read or can be read but the identification information is wrong; the second QR code is a QR code of real information, which can be read and identified.

[0062] The results obtained refer to Figure 3, the first QR code was visible to the naked eye in daylight and could be scanned to reveal false information (see Figure 3 a), while under 254nm UV irradiation in sunlight or irradiation (see Figure 3 After b and c), both codes are unscannable due to the interference between the phosphorescent QR code pattern and the first QR code; only under dark conditions, 254nm UV irradiation or irradiation (see Figure 3 After d and e), the second QR code with real information can be scanned, thus achieving the effect of anti-counterfeiting and encryption.

[0063] Example 4

[0064] The difference between this embodiment and embodiment 1 is that the glass substrate is replaced by a flexible self-adhesive PET label sticker.

[0065] Weigh 3 mg of rhodamine B into a 10 mL centrifuge tube and add 6 mL of deionized water to dissolve it to prepare a 0.5 mg / mL rhodamine B solution.

[0066] Weigh 150mg of the copolymer into a 10mL centrifuge tube, add 600µL of the Rhodamine B solution, and then add 2400µL of deionized water. Ultrasonicate the solution in an ultrasonic cleaner for 20 minutes to evenly disperse the copolymer and thoroughly mix it with the Rhodamine B. After cooling to room temperature, apply 400µL of the solution to a self-adhesive PET label. Dry the label in a 60°C air drying oven for 20-15 minutes to completely remove the moisture, forming a phosphorescent film. Then, fumigate the label with 60°C water until the phosphorescence at the marked area is completely quenched.

[0067] The generated QR code image is imported into the laser marking machine, and the laser marking speed is adjusted to 10mm / s, the power to 15%, and the frequency to 80kHz. Finally, the QR code is printed on the phosphorescent film using the set parameters to obtain the anti-counterfeiting label.

[0068] The results obtained refer to Figure 4 In addition to heating the QR code pattern at a fixed point and restoring phosphorescence, the UV laser also partially removes the fluorescent dye. Therefore, the resulting QR code is difficult to identify with the naked eye under sunlight (see Figure 4 a); in sunlight, 254 nm UV irradiation or removal of irradiation (see Figure 4 b and c), the QR code is not scannable; under dark conditions, 254nm UV irradiation (see Figure 4 After (d), the QR code cannot be scanned; only under dark conditions, 254nm ultraviolet radiation can remove it (see Figure 4 After the QR code is scanned, the information can be obtained, thus achieving the effect of anti-counterfeiting and encryption. In addition, the label paper can be directly pasted on the item (see Figure 4f, g, h), thereby obtaining a convenient encryption tag that can transfer the encryption pattern arbitrarily.

[0069] Example 5

[0070] The difference between this embodiment and embodiment 1 is that: the two-dimensional code on the phosphorescent film is repeatedly erased and marked; and water vapor is generated by human exhalation to quench the phosphorescence.

[0071] Weigh 3 mg of rhodamine B into a 10 mL centrifuge tube and add 6 mL of deionized water to dissolve it to prepare a 0.5 mg / mL rhodamine B solution.

[0072] Weigh 150mg of the copolymer into a 10mL centrifuge tube, add 600µL of the Rhodamine B solution, and then add 2400µL of deionized water. Ultrasonicate the solution in an ultrasonic cleaner for 20 minutes to evenly disperse the copolymer and thoroughly mix it with the Rhodamine B. After cooling to room temperature, apply 400µL of the solution to a cleaned glass substrate and dry it on an 80°C hot plate for 15-20 minutes to completely remove the moisture, forming a phosphorescent film. Then, fumigate with 60°C water until the marked area is completely quenched.

[0073] The generated QR code image is imported into a laser marking machine. The laser marking speed is adjusted to 10 mm / s, the power is set to 15%, and the frequency is adjusted to 80 kHz. The QR code is then printed onto the phosphorescent film to produce the anti-counterfeiting label. The pattern is then quenched by exhaling, resulting in a blank anti-counterfeiting label with the QR code erased, ready for further marking.

[0074] The results refer to Figure 5 The above steps were repeated three times, each time with a different QR code printed on the phosphorescent film. This demonstrates that the phosphorescent film used as an encryption label in the present invention can be reused. That is, after quenching the encryption pattern with water vapor, a new encryption pattern can be printed again, thus enabling the reuse of the anti-counterfeiting label.

[0075] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A patterned encryption method combining room temperature phosphorescence and ultraviolet laser marking, characterized in that: The following steps are involved: S1. Dispersing a room temperature phosphorescent material having an ultraviolet absorption wavelength of 240 nm to 340 nm, capable of water absorption quenching and thermal recovery of phosphorescence, and a water-soluble fluorescent dye serving as a Forster resonance energy transfer acceptor in deionized water to obtain a mixed solution, wherein the concentration of the room temperature phosphorescent material is 25 mg / mL to 75 mg / mL, and the doping amount of the water-soluble fluorescent dye is 0 to 0.4 wt %; S2, coating the mixed solution obtained in step S1 on a substrate, volatilizing the solvent to form a phosphorescent film on the substrate; then applying water vapor at 35-80°C to the phosphorescent film to completely quench the phosphorescence; S3, importing a preset encrypted pattern into the ultraviolet laser marking machine, and generating the encrypted pattern on the phosphor film through a marking operation; The room temperature phosphorescent material is a copolymer having the following structure: Among them, the ratio of m to n is 1:100~1:1000; The parameter ranges of the ultraviolet laser marking are: marking rate of 5 mm / s to 25 mm / s, marking power of 10% to 50%, and marking frequency of 60 kHz to 100 kHz.

2. The patterned encryption method combining room temperature phosphorescence and ultraviolet laser marking according to claim 1, characterized in that: The room temperature phosphorescent material is obtained by polymerization of acrylamide and 4-(4-vinylphenyl)pyridine.

3. The patterned encryption method combining room temperature phosphorescence and ultraviolet laser marking according to claim 1, characterized in that: The water-soluble fluorescent dye is rhodamine B.

4. The patterned encryption method combining room temperature phosphorescence and ultraviolet laser marking according to claim 1, characterized in that: The image format of the encrypted pattern imported by the ultraviolet laser marking machine is a grayscale image.

5. The pattern encryption method combining room temperature phosphorescence and ultraviolet laser marking according to claim 1, characterized in that: The encryption pattern is a QR code or a bar code.

6. The patterned encryption method combining room temperature phosphorescence and ultraviolet laser marking according to claim 1, characterized in that: The substrate is a glass substrate or a self-adhesive PET label sticker.

7. The pattern encryption method combining room temperature phosphorescence and ultraviolet laser marking according to any one of claims 1 to 6, characterized in that: Before step S2, the method further includes the following steps: Laminating the metal sheet to the other side of the substrate on which the phosphorescent film is formed, wherein the substrate is made of a transparent material; A preset encrypted pattern different from the encrypted pattern in step S3 is introduced into the ultraviolet laser marking machine. Through the marking operation, the encrypted pattern is etched on the substrate through the metal sheet, and the encrypted pattern on the substrate overlaps with the encrypted pattern generated on the phosphor film in step S3.

8. An anti-counterfeiting label, characterized in that: A patterned encryption method combining room temperature phosphorescence and ultraviolet laser marking as described in any one of claims 1 to 7 is adopted.

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