Weather-resistant room-temperature phosphorescent anti-counterfeit label and preparation method thereof

Abstract

The invention discloses a weather-resistant room-temperature phosphorescent anti-counterfeit label and a preparation method thereof.The preparation method of the weather-resistant room-temperature phosphorescent anti-counterfeit label comprises the following steps that melamine, a formaldehyde solution and a tetrahydrofuran solution are mixed to be uniform, and a reaction solution is obtained; adjusting the pH value of the reaction liquid to 7-8, and then carrying out a heating reaction; removing part of the solvent in vacuum to obtain a doped prepolymer solution; coating a substrate with the doped prepolymer solution, and then heating and curing through a temperature control program to obtain the weather-resistant room-temperature phosphorescent film, and etching a pattern mark on the weather-resistant room-temperature phosphorescent film by adopting an ultraviolet laser marking machine to obtain the weather-resistant room-temperature phosphorescent anti-counterfeit label. The weather-resistant room-temperature phosphorescent film prepared by the invention has high transparency and excellent weather resistance, can be combined with a laser direct writing process, and can be applied to the technical field of organic phosphorescent optical anti-counterfeiting encryption.

Description

Technical Field

[0001] This invention belongs to the field of patterned anti-counterfeiting technology, specifically relating to a weather-resistant room temperature phosphorescent anti-counterfeiting label and its preparation method. Background Technology

[0002] Organic room-temperature phosphorescent anti-counterfeiting encryption technology relies on patterning to achieve its core function. Existing patterning processes include laser direct writing, screen printing, and inkjet printing. Among these, screen printing and inkjet printing require complex plate making and cumbersome procedures, and have poor adaptability and inconvenient pattern adjustment, making it difficult to meet diverse anti-counterfeiting needs. Laser direct writing, on the other hand, requires no plate making, is flexible in operation, and can directly draw patterns as needed, offering great convenience. It also has high precision and micro-nano processing capabilities, making it the core preferred choice for high-end anti-counterfeiting. However, existing melamine-formaldehyde resin-based phosphorescent films are mostly prepared using hot-pressing processes. But films produced by hot pressing have inherent defects such as high brittleness and low transparency. When directly using laser direct writing for patterning, the film is prone to damage and carbonization. At the same time, the low transparency also makes it impossible to accurately form effective phosphorescent patterns with lasers, posing a core technical challenge of process compatibility. Summary of the Invention

[0003] To address the problems mentioned in the background section, the present invention aims to provide a weather-resistant room-temperature phosphorescent anti-counterfeiting label and its preparation method. The weather-resistant room-temperature phosphorescent film obtained by the present invention possesses high transparency and excellent weather resistance, can be combined with laser direct writing technology, and can be applied in the field of organic phosphorescent optical anti-counterfeiting and encryption technology.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On one hand, the present invention provides a method for preparing a weather-resistant room-temperature phosphorescent anti-counterfeiting label, comprising the following steps:

[0005] (1) Melamine, formaldehyde solution and The tetrahydrofuran solution was mixed thoroughly to obtain the reaction solution;

[0006] (2) Adjust the pH of the reaction solution in step (1) to 7-8, and then heat the reaction; then remove part of the solvent by vacuum to obtain the doped prepolymer solution;

[0007] (3) The doped prepolymer solution described in step (2) is coated onto the substrate and then heated and cured by a temperature control program to obtain a weather-resistant room temperature phosphorescent film;

[0008] (4) Using an ultraviolet laser marking machine, the pattern mark is etched onto the weather-resistant room temperature phosphorescent film described in step (3) to obtain the weather-resistant room temperature phosphorescent anti-counterfeiting label.

[0009] This invention selects phosphorescent monomers When incorporated into melamine-formaldehyde resin, the dense three-dimensional network structure of the melamine-formaldehyde resin matrix not only inhibits the movement of guest molecules but also provides excellent water resistance, thereby endowing the weather-resistant room temperature phosphorescent film with excellent photoactivation properties and weather resistance.

[0010] Further, the formaldehyde in the formaldehyde solution described in step (1), In tetrahydrofuran solution The mass ratio of melamine to melamine is 0.8325:0.0019:1.

[0011] Further, the formaldehyde solution mentioned in step (1) is an aqueous formaldehyde solution.

[0012] Furthermore, the concentration of the formaldehyde aqueous solution is 37 wt%.

[0013] Further, the steps described in step (1) The concentration of the tetrahydrofuran solution was 10 mg / mL.

[0014] Furthermore, the heating reaction in step (2) is carried out at a temperature of 85–90°C for 2 hours.

[0015] And / or, in the doped prepolymer solution described in step (2), The doping concentration is 0.1 wt%.

[0016] Further, the pH in step (2) is adjusted by a 10 wt% triethanolamine aqueous solution.

[0017] Furthermore, the conditions for vacuum removal of part of the solvent in step (2) are: temperature of 80℃, gauge pressure of -0.06 to -0.08 MPa, and time of 35 to 45 min.

[0018] Furthermore, the substrate mentioned in step (3) is a glass substrate;

[0019] And / or, the coating amount of the doped prepolymer solution on the substrate in step (3) is: 400–500 μL was coated onto the glass substrate.

[0020] Further, the temperature control procedure in step (3) is as follows: heat to cure at 80°C for 24 hours, then slowly cool to 70°C and hold for 12 hours, and finally slowly cool to room temperature. The cooling rate involved in the entire process is 2.5°C / h. If the temperature control procedure is not limited to this, it will lead to insufficient crosslinking and / or film breakage. Under this limited condition, the crosslinking is sufficient, and the prepared weather-resistant room temperature phosphorescent film will not break.

[0021] Furthermore, the process parameters of the ultraviolet laser marking machine mentioned in step (4) are: rated power of 5W, speed of 100mm / s, power of 60%, and frequency of 80kHz.

[0022] Furthermore, the pattern mark in step (4) is text, pattern, or a combination of text and pattern.

[0023] On the other hand, the present invention provides a weather-resistant room temperature phosphorescent anti-counterfeiting label, which is prepared by any of the preparation methods described above.

[0024] On the other hand, the present invention provides a method for displaying pattern markings on the above-mentioned weather-resistant room temperature phosphorescent anti-counterfeiting label, comprising the following steps:

[0025] Irradiate the weather-resistant room temperature phosphorescent anti-counterfeiting label described above under an ultraviolet lamp for 2-3 seconds, and the pattern mark can be observed after the light source is removed.

[0026] Furthermore, the wavelength of the ultraviolet lamp is 365nm.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] (1) The preparation method of the present invention organically combines melamine-formaldehyde resin-based weather-resistant room temperature phosphorescent film with ultraviolet laser marking technology. The marking process is carried out by using an ultraviolet laser marking machine under specific process parameters. The pattern is finely constructed by etching. The pattern mark formed by the characteristic traces formed by etching cannot be directly identified by the naked eye under visible light conditions, nor can it be identified by conventional scanning equipment. Finally, the concealment effect of encrypted pattern is achieved.

[0029] (2) The weather-resistant room temperature phosphorescent anti-counterfeiting label of the present invention is invisible under fluorescent light and under 365nm ultraviolet light immediately after it is applied. It is only visible after the ultraviolet light is turned off and it exists for a long time, thereby achieving information encryption.

[0030] (3) The weather-resistant room temperature phosphorescent anti-counterfeiting label of the present invention can achieve liquid phase phosphorescence, with high transparency, excellent weather resistance and longer shelf life. Even after being soaked in water for 1 month, placed in a salt spray environment for 2 weeks and continuously irradiated under a 254nm ultraviolet lamp for 2 weeks, its pattern is still clearly visible after being excited by 365nm ultraviolet light, making it more applicable. Attached Figure Description

[0031] Figure 1 The image shows the weather resistance test results of the weather-resistant room temperature phosphorescent anti-counterfeiting label prepared in Example 1 of this invention.

[0032] Figure 2The image shows the haze test results of the weather-resistant room temperature phosphorescent film prepared in Example 1 of the present invention. The inset shows a photograph of the weather-resistant room temperature phosphorescent film under sunlight (left) and a photograph of the afterglow after being irradiated under a 365nm ultraviolet lamp for 2 seconds and then the ultraviolet light source was removed (right).

[0033] Figure 3 The fluorescence excitation spectrum of the weather-resistant room-temperature phosphorescent thin film prepared in Example 1 of this invention;

[0034] Figure 4 The steady-state fluorescence spectrum of the weather-resistant room-temperature phosphorescent thin film prepared in Example 1 of this invention;

[0035] Figure 5 The delayed fluorescence spectrum of the weather-resistant room-temperature phosphorescent thin film prepared in Example 1 of this invention is shown.

[0036] Figure 6 This is a delayed emission decay curve of the weather-resistant room temperature phosphorescent thin film prepared in Example 1 of the present invention;

[0037] Figure 7 The above is a graph showing the phosphorescence quantum yield of the weather-resistant room temperature phosphorescent thin film prepared in Example 1 of this invention.

[0038] Figure 8 This is a diagram illustrating the laser marking process of the weather-resistant room-temperature phosphorescent thin film prepared in Example 1 of the present invention.

[0039] Figure 9 The one used in Embodiment 1 of the present invention Spatial geometry configurations before and after optimization in Gaussian 16 program;

[0040] Figure 10 The images show the hot-pressed film (left) prepared in Comparative Example 1 and the weather-resistant room-temperature phosphorescent film (right) prepared in Example 1 after being marked with the same laser parameters. The area marked with laser is circled in red. Detailed Implementation

[0041] To better understand the content of this invention, the following detailed description is provided in conjunction with specific implementation methods. However, the scope of protection of this invention is not limited to the following embodiments.

[0042] Unless otherwise specified, the test reagents used in the following examples are all conventional biochemical reagents; and the experimental methods described are all conventional methods unless otherwise specified.

[0043] Example 1

[0044] Preparation of weather-resistant room temperature phosphorescent anti-counterfeiting labels:

[0045] Take 2g of melamine, 4.50g of formaldehyde aqueous solution (concentration 37wt%), and 380μL of... A tetrahydrofuran solution (10 mg / mL) was stirred until homogeneous to obtain a reaction solution. 100 μL of a 10 wt% triethanolamine aqueous solution was added to adjust the pH of the reaction solution to 7. The temperature was raised to 85 °C, and the reaction was carried out for 2 h. Subsequently, the solvent was removed under vacuum at 80 °C and a gauge pressure of -0.07 MPa for 35 min to obtain a doped prepolymer solution. 500 μL of the doped prepolymer solution was coated onto a cleaned... On a glass substrate, the film is heated and cured at 80°C for 24 hours, then slowly cooled to 70°C and held for 12 hours, and finally slowly cooled to room temperature. The cooling rate involved in the whole process is 2.5°C / h, and a transparent, weather-resistant room temperature phosphorescent film is finally obtained.

[0046] Import the three white-background portrait images into a 5W UV laser marking machine, and set the image size to [size to be specified]. Adjust the laser marking speed to 100 mm / s, power to 60%, and frequency to 80 kHz. Place the weather-resistant room temperature phosphorescent film below the laser and adjust the laser height so that the laser spot is clearly focused on the exact center of the film. Run the marking machine and, referring to the original pattern, etch an invisible pattern onto the film using ultraviolet laser, thus obtaining a weather-resistant room temperature phosphorescent anti-counterfeiting label.

[0047] The specific steps of the method for revealing the pattern information on the weather-resistant room temperature phosphorescent anti-counterfeiting label prepared above are as follows:

[0048] The patterns on weather-resistant room temperature phosphorescent anti-counterfeiting labels are invisible in sunlight. They can only be observed after being exposed to a 365nm ultraviolet lamp for 2-3 seconds and the light source is removed.

[0049] Comparative Example 1

[0050] Take 2g of melamine, 4.50g of formaldehyde aqueous solution (concentration 37wt%), and 380μL of... A tetrahydrofuran solution (10 mg / mL) was stirred until homogeneous to obtain a reaction solution. 100 μL of a 10 wt% triethanolamine aqueous solution was added to adjust the pH of the reaction solution to 7. The temperature was raised to 85 °C, and the reaction was carried out for 35 min. Subsequently, the solution was vacuum dried at 85 °C and a gauge pressure of -0.07 MPa for 4 h to obtain phosphorescent polymer powder. The obtained phosphorescent polymer powder was hot-pressed at 170 °C and a pressure of 17 MPa for 1 h. After natural cooling to room temperature, a hot-pressed film was obtained.

[0051] Characterization and performance testing:

[0052] The three weather-resistant room-temperature phosphorescent anti-counterfeiting labels prepared in Example 1 were respectively immersed in water for one month, placed in a salt spray environment (generated by heating a 5wt% sodium chloride aqueous solution using a salt spray machine) for two weeks, and continuously irradiated under a 254nm ultraviolet lamp for two weeks. After removing the labels, they were irradiated under a 365nm ultraviolet lamp for 2 seconds, and then the ultraviolet light source was removed. The pattern display was observed, and the results are as follows. Figure 1 As shown. From Figure 1 As can be seen, the pattern of the weather-resistant room temperature phosphorescent anti-counterfeiting label is still clearly visible, indicating that the weather-resistant room temperature phosphorescent anti-counterfeiting label prepared in Example 1 has excellent weather resistance.

[0053] The haze of the weather-resistant room-temperature phosphorescent film prepared in Example 1 was tested, and the results are as follows: Figure 2 As shown. From Figure 2 As can be seen, its haze is <2.2% in the visible light range, and its transmittance is between 84% and 92%. The inset shows a photograph of the weather-resistant room temperature phosphorescent film under sunlight (left) and a photograph of its afterglow after being irradiated with a 365nm ultraviolet lamp for 2 seconds and then the ultraviolet light source was removed (right). In both cases, the English words on the paper can be clearly observed through the film, indicating that the weather-resistant room temperature phosphorescent film has high transparency.

[0054] Fluorescence excitation tests were performed on the weather-resistant room-temperature phosphorescent thin film prepared in Example 1, and the results are as follows: Figure 3 As shown. From Figure 3 As can be seen, the fluorescence excitation range of the weather-resistant room temperature phosphorescent film is 260–380 nm, indicating that the weather-resistant room temperature phosphorescent film can be excited by 365 nm ultraviolet light.

[0055] Fluorescence emission tests were performed on the weather-resistant room-temperature phosphorescent thin film prepared in Example 1, and the results are as follows: Figure 4 As shown. From Figure 4 As can be seen, the steady-state fluorescence of the weather-resistant room-temperature phosphorescent film is located in the range of 360–450 nm.

[0056] The weather-resistant room-temperature phosphorescent thin film prepared in Example 1 was subjected to delayed fluorescence emission testing, and the results are as follows: Figure 5 As shown. From Figure 5 As can be seen, the delayed fluorescence of the weather-resistant room temperature phosphorescent film is in the range of 500-650 nm, indicating that the weather-resistant room temperature phosphorescent film can emit conspicuous yellow-green phosphorescence.

[0057] The phosphorescence lifetime of the weather-resistant room temperature phosphorescent film prepared in Example 1 was tested, and the results are as follows: Figure 6 As shown. From Figure 6It can be seen that the phosphorescence lifetime of the weather-resistant room temperature phosphorescent film is 1.99s, indicating that the weather-resistant room temperature phosphorescent film in Example 1 has good long afterglow luminescence performance.

[0058] The phosphorescence quantum yield of the weather-resistant room-temperature phosphorescent thin film prepared in Example 1 was tested, and the results are as follows: Figure 7 As shown. From Figure 7 As can be seen, the phosphorescence quantum yield of the weather-resistant room temperature phosphorescent film is as high as 55.52%, indicating that the non-radiative energy loss of the weather-resistant room temperature phosphorescent film after excitation is small, the luminescence efficiency is high, which helps to prolong the afterglow time and the luminescence characteristics are stable.

[0059] The weather-resistant room-temperature phosphorescent thin film prepared in Example 1 was laser-marked, such as... Figure 8 As shown. From Figure 8 As can be seen, a noticeable trailing effect occurred during the laser marking process, which verifies... Figure 7 The fact that phosphorus photon yield is medium to high.

[0060] The example used in Example 1 The spatial geometry before and after optimization in the Gaussian 16 program is as follows: Figure 9 As shown. From Figure 9 As can be seen from the above, this invention successfully utilizes non-planar phosphorescent guest molecules (existing melamine-formaldehyde resin doping systems generally use planar guest molecules; non-planar guest molecules typically suffer from severe non-radiative inactivation, resulting in poor luminescence performance; the phosphorescent guest molecules used in this invention...). (With good luminescence properties), a weather-resistant room temperature phosphorescent thin film with long lifetime, high phosphorescence quantum yield, high transparency and excellent weather resistance was prepared.

[0061] The hot-pressed film prepared in Comparative Example 1 and the weather-resistant room-temperature phosphorescent film prepared in Example 1 of this invention were marked with the same laser parameters (rated power of 5W, velocity of 100mm / s, power of 60%, frequency of 80kHz). Figure 10 As shown, the area within the red circle is the laser marking area. From Figure 10 As can be seen, the hot-pressed film showed obvious cracking under the marking conditions, while the weather-resistant room temperature phosphorescent film prepared in Example 1 showed no obvious traces. This also confirms that in melamine-formaldehyde resin-based doped room temperature phosphorescent materials, the weather-resistant room temperature phosphorescent film prepared by the process in Example 1 has better processing performance than the traditional hot-pressed film.

[0062] The above description is only a specific embodiment of the present invention and not all embodiments. Any equivalent modifications made by those skilled in the art to the technical solutions of the present invention by reading the present invention specification shall be covered by the claims of the present invention.

Claims

1. A method for preparing a weather-resistant room-temperature phosphorescent anti-counterfeiting label, characterized in that, Includes the following steps: (1) Melamine, formaldehyde solution and The tetrahydrofuran solution was mixed thoroughly to obtain the reaction solution; (2) Adjust the pH of the reaction solution in step (1) to 7-8, and then heat the reaction; then remove part of the solvent by vacuum to obtain the doped prepolymer solution; (3) The doped prepolymer solution described in step (2) is coated onto the substrate and then heated and cured by a temperature control program to obtain a weather-resistant room temperature phosphorescent film; (4) Using an ultraviolet laser marking machine, the pattern mark is etched onto the weather-resistant room temperature phosphorescent film described in step (3) to obtain the weather-resistant room temperature phosphorescent anti-counterfeiting label.

2. The method for preparing the weather-resistant room temperature phosphorescent anti-counterfeiting label according to claim 1, characterized in that, The formaldehyde solution mentioned in step (1) is an aqueous formaldehyde solution; And / or, the formaldehyde in the formaldehyde solution described in step (1), In tetrahydrofuran solution The mass ratio of melamine to melamine is 0.8325:0.0019:

1.

3. The method for preparing the weather-resistant room temperature phosphorescent anti-counterfeiting label according to claim 1, characterized in that, The heating reaction in step (2) is carried out at a temperature of 85-90°C for 2 hours. And / or, in the doped prepolymer solution described in step (2), The doping concentration is 0.1 wt%.

4. The method for preparing the weather-resistant room temperature phosphorescent anti-counterfeiting label according to claim 1, characterized in that, The substrate mentioned in step (3) is a glass substrate; And / or, the coating amount of the doped prepolymer solution on the substrate in step (3) is: 400–500 μL was coated onto the glass substrate.

5. The method for preparing the weather-resistant room temperature phosphorescent anti-counterfeiting label according to claim 1, characterized in that, The temperature control procedure in step (3) is as follows: heat and cure at 80°C for 24 hours, then slowly cool down to 70°C and keep warm for 12 hours, and finally slowly cool down to room temperature. The cooling rate involved in the whole process is 2.5°C / h.

6. The method for preparing the weather-resistant room temperature phosphorescent anti-counterfeiting label according to claim 1, characterized in that, The process parameters of the ultraviolet laser marking machine mentioned in step (4) are: rated power of 5W, speed of 100mm / s, power of 60%, and frequency of 80kHz.

7. The method for preparing the weather-resistant room temperature phosphorescent anti-counterfeiting label according to claim 1, characterized in that, The pattern mark in step (4) is text, pattern, or a combination of text and pattern.

8. A weather-resistant room-temperature phosphorescent anti-counterfeiting label, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 7.

9. The method for displaying pattern markings on a weather-resistant room-temperature phosphorescent anti-counterfeiting label as described in claim 8, characterized in that, Includes the following steps: The weather-resistant room temperature phosphorescent anti-counterfeiting label of claim 8 is irradiated under an ultraviolet lamp for 2-3 seconds, and the pattern mark can be observed after the light source is removed.

10. The method for displaying pattern markings on a weather-resistant room-temperature phosphorescent anti-counterfeiting label according to claim 9, characterized in that, The wavelength of the ultraviolet lamp is 365nm.

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