Laser high-sensitivity thin film for low-fluorescence PC identification card and preparation method of laser high-sensitivity thin film

Abstract

The invention relates to the technical field of high polymer materials, in particular to a laser high-sensitivity film for a low-fluorescence PC identification card and a preparation method thereof.The preparation method comprises the steps that 10 parts of PC resin is ground into 200-mesh powder according to the proportion, the powder, a triazine light stabilizer, a nickel complex and a laser photosensitizer are stirred at a high speed for 10 min (400 rpm), then the mixture is cooled to 60 DEG C or below at a low speed, and the mixture is discharged to a discharging bin to obtain a mixture; carrying out twin-screw granulation to obtain high-concentration light stabilizer master batch; drying the master batch at 80 DEG C for 4 hours, mixing the master batch with 90 parts of PC resin, and preparing a PC film through an extrusion casting machine; finally, the PC film is cooled and shaped through equipment such as a melt filter, and the uniformly-dispersed low-fluorescence PC film is obtained, so that the problem that a film material in the prior art is difficult to maintain original excellent mechanical and optical properties of polycarbonate is solved, background fluorescence of the material under the ultraviolet light condition can be effectively inhibited, and the low-fluorescence PC film is prepared. And the technical problem of color interference or transparency reduction is not introduced.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a low-fluorescence PC card laser-sensitive thin film and its preparation method. Background Technology

[0002] Polycarbonate (PC) is a colorless and transparent thermoplastic material, often referred to as a transparent alloy. As an amorphous plastic, PC possesses excellent comprehensive properties, including high mechanical strength, good toughness, good heat and weather resistance, high dimensional stability, easy coloring, low water absorption, and inherent flame retardant properties without additives. PC has a heat distortion temperature of 135-143℃ and can be used continuously at operating temperatures of 120-130℃. It also exhibits certain low-temperature resistance, allowing for long-term use at -40℃. Due to its outstanding comprehensive properties, PC is widely used in the field of document issuance in Europe and America, such as passports, ID cards, and driver's licenses. PC document cards have high anti-counterfeiting features; the card layers are heat-sealed at high temperatures, making it impossible to tamper with or counterfeit the document without damaging the card.

[0003] However, the conjugated double bonds in the molecular structure of PC materials cause them to exhibit background fluorescence under ultraviolet light at specific wavelengths (such as 365nm). This autofluorescence can significantly interfere with the verification of counterfeit documents, particularly affecting the recognition of underlying fluorescent anti-counterfeiting inks and laser markings, thus reducing the accuracy and reliability of authenticity determination. Therefore, in high-end anti-counterfeiting card applications, suppressing or eliminating the material's own fluorescence has become a key technical requirement for improving overall anti-counterfeiting performance.

[0004] To suppress fluorescence in materials, fluorescence quenching technology is commonly used, which involves adding quenchers to reduce or eliminate the material's luminescence intensity. Quenching mechanisms mainly fall into two categories: dynamic quenching and static quenching. Dynamic quenching originates from the interaction between the quencher and excited-state fluorescent molecules, while static quenching weakens fluorescence by forming a non-luminescent complex with the ground-state fluorescent molecules. Currently used organonitrile complex quenchers, such as AM-101 (2,2′-thiobis(4-tert-octylphenoxy)nickel) and NBC (N,N-di-n-butyldithiocarbamate), while possessing some fluorescence suppression effects, often introduce color (such as a green tint) due to the presence of nickel ions in their molecules, making them unsuitable for high-transparency card materials and limiting their application in optical-grade PC products.

[0005] In summary, existing thin film materials struggle to effectively suppress background fluorescence under ultraviolet light conditions while maintaining the excellent mechanical and optical properties of polycarbonate, without introducing color interference or reducing transparency. Summary of the Invention

[0006] The purpose of this invention is to provide a low-fluorescence PC card laser-sensitive film and its preparation method, aiming to solve the technical problem that existing film materials are difficult to maintain the excellent mechanical and optical properties of polycarbonate while effectively suppressing the background fluorescence of the material under ultraviolet light conditions without introducing color interference or reducing transparency.

[0007] To achieve the above objectives, the present invention employs a low-fluorescence PC card laser-sensitive film comprising 100 parts PC resin, 0.001-0.008 parts triazine light stabilizer, 0.0002-0.001 parts nickel complex and 0.001 parts laser photosensitizer.

[0008] The triazine light stabilizer is one of UV-1577, UV-1164, and UV-400, and the nickel complex is one of AM-101 (2,2'-thiobis(4-tert-octylphenoloxy)nickel) and NBC (N,N-di-n-butyldithiocarbamate nickel).

[0009] The laser photosensitizer is molybdenum sulfide with a particle size of 10 nm, a purity of 99.99%, and a specific surface area of ​​15 m². 2 / g.

[0010] This invention also provides a method for preparing a low-fluorescence PC card laser-sensitive film, used to prepare the low-fluorescence PC card laser-sensitive film as described above.

[0011] Includes the following steps:

[0012] Process 10 parts of PC resin into 200-mesh PC powder using a grinding mill according to the specified ratio;

[0013] PC powder, triazine light stabilizer, nickel complex, and laser photosensitizer are first stirred at high speed for 10 minutes at 400 rpm in a high-speed mixer, then cooled at low speed to below 60°C, and discharged into the feed hopper to obtain a mixture.

[0014] The mixture is fed to a twin-screw granulator via a feed screw to obtain high-concentration light stabilizer masterbatch.

[0015] High-concentration light stabilizer masterbatch was discharged into a heated mixing tank and dried at 80°C for 4 hours. It was then mixed with 90 parts of PC resin through a mixer and fed to an extruder. PC film was prepared by an extrusion casting machine.

[0016] The PC film is cooled and shaped by passing it through a melt filter, melt pump, mold, and three-roll calender to obtain a uniformly dispersed low-fluorescence PC film.

[0017] In the step "the mixture is fed to a twin-screw granulator via a feed screw to obtain a high-concentration light stabilizer masterbatch":

[0018] The twin-screw granulator has an aspect ratio of 45:1, and the process temperatures are 240-260℃ for the extruder, 250-270℃ for the filter, and 260-270℃ for the extruder head. The filter screen is a 3-layer 400-mesh metal mesh.

[0019] In the step "cooling and shaping the PC film through a melt filter, melt pump, mold, and three-roll calender to obtain a uniformly dispersed low-fluorescence PC film":

[0020] The filter screen has an 8-layer structure (50 mesh / 80 mesh / 150 mesh / 500 mesh / 500 mesh / 150 mesh / 80 mesh / 50 mesh), the melt pump is 260-290℃ and the speed is 45rpm, the mold temperature is 260-290℃, and the three-roll calender is 110-130℃.

[0021] In the step "cooling and shaping the PC film through a melt filter, melt pump, mold, and three-roll calender to obtain a uniformly dispersed low-fluorescence PC film":

[0022] A vision inspection system based on machine learning algorithms is used to monitor the surface defects and fluorescence uniformity of the thin film online; the system performs the following steps:

[0023] Image data of the thin film surface is acquired in real time using a high-speed linear CCD camera;

[0024] Image data is transmitted to an industrial control computer, where a pre-trained deep learning convolutional neural network (CNN) model is used to perform real-time analysis of the image.

[0025] The CNN model identifies bright spots, stripes, bubble defects, and fluorescence intensity distribution in the image;

[0026] If a defect or fluorescence uniformity exceeds a preset threshold, the system will automatically alarm and record the defect location information, while simultaneously feeding the signal back to the central control system. The central control system will adaptively fine-tune the extruder temperature, screw speed, or the roll gap and temperature of the three-roll calender according to the algorithm model.

[0027] The training data for the CNN model includes thousands of images of qualified and unqualified films with various annotations, which are trained through supervised learning. The adaptive fine-tuning algorithm of the central control system is either a PID control algorithm or a fuzzy control algorithm.

[0028] This invention discloses a low-fluorescence PC laser-sensitive film for ID cards and its preparation method. First, 10 parts of PC resin are processed into 200-mesh PC powder using a grinding mill. The PC powder, along with a triazine light stabilizer, a nickel complex, and a laser photosensitizer, are stirred at high speed for 10 minutes at 400 rpm using a high-speed mixer, then cooled at low speed to below 60°C and discharged into a hopper to obtain a mixture. The mixture is then fed to a twin-screw extruder via a feeding screw to obtain a high-concentration light stabilizer masterbatch. The high-concentration light stabilizer masterbatch is discharged into a heated mixing tank and dried at 80°C for 4 hours. It is then mixed with 90 parts of PC resin using a mixer and fed to an extruder. A PC film is prepared using an extrusion casting machine. The PC film is then cooled and shaped using a melt filter, melt pump, mold, and three-roll calender to obtain a uniformly dispersed low-fluorescence PC film.

[0029] This invention utilizes a combination of triazine light stabilizers and a small amount of nickel complex to obtain a low-fluorescence PC card film;

[0030] This invention uses a grinding process to combine PC resin with powder light stabilizer and laser photosensitizer, so that the light stabilizer and laser photosensitizer are uniformly dispersed in high viscosity resin.

[0031] The PC film obtained by this invention, through the absorption of ultraviolet light by triazine light stabilizers and nickel complexes, has an ultraviolet transmittance between 4% and 10%, which will not affect the display effect of the underlying ultraviolet anti-counterfeiting ink and laser graphics.

[0032] This invention can reduce the influence of nickel complexes on the color of transparent films.

[0033] The molybdenum sulfide laser photosensitizer film prepared by this invention can achieve 256 gray levels of infrared laser etching.

[0034] This approach solves the technical problem in existing technologies where thin film materials cannot effectively suppress background fluorescence under ultraviolet light conditions while maintaining the excellent mechanical and optical properties of polycarbonate, without introducing color interference or reducing transparency. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a flowchart of the preparation method of the low-fluorescence PC card laser-sensitive film of the present invention. Detailed Implementation

[0037] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0038] This invention provides a low-fluorescence PC card laser-sensitive film, comprising 100 parts PC resin, 0.001-0.008 parts triazine light stabilizer, 0.0002-0.001 parts nickel complex and 0.001 parts laser photosensitizer.

[0039] The triazine light stabilizer is one of UV-1577, UV-1164, and UV-400, and the nickel complex is one of AM-101 (2,2'-thiobis(4-tert-octylphenoloxy)nickel) and NBC (N,N-di-n-butyldithiocarbamate nickel).

[0040] The laser photosensitizer is molybdenum sulfide with a particle size of 10 nm, a purity of 99.99%, and a specific surface area of ​​15 m². 2 / g.

[0041] Please see Figure 1 , Figure 1 This is a flowchart of the preparation method of the low-fluorescence PC card laser-sensitive film of the present invention.

[0042] This invention also provides a method for preparing a low-fluorescence PC card laser-sensitive film, used to prepare the low-fluorescence PC card laser-sensitive film as described above.

[0043] Includes the following steps:

[0044] S1. Process 10 parts of PC resin into 200-mesh PC powder using a grinding mill according to the specified ratio;

[0045] S2. The PC powder, triazine light stabilizer, nickel complex, and laser photosensitizer are first stirred at high speed for 10 minutes at 400 rpm in a high-speed mixer, then cooled at low speed to below 60°C, and discharged into the feed hopper to obtain a mixture.

[0046] In this specific embodiment, the moisture content of the powder is controlled to be below 100 ppm.

[0047] S3. The mixture is fed to a twin-screw granulator via a feeding screw to obtain high-concentration light stabilizer masterbatch;

[0048] In this specific embodiment, the twin-screw granulator has an aspect ratio of 45:1, and the process temperatures are 240-260℃ for the extruder, 250-270℃ for the filter, and 260-270℃ for the extruder head. The filter screen is a 3-layer 400-mesh metal mesh.

[0049] S4. High-concentration light stabilizer masterbatch is discharged into a heated mixing tank and dried at 80°C for 4 hours. It is then mixed with 90 parts of PC resin through a mixer and fed to an extruder. PC film is prepared by extrusion casting machine.

[0050] S5. The PC film is cooled and shaped by passing it through a melt filter, melt pump, mold, and three-roll calender to obtain a uniformly dispersed low-fluorescence PC film.

[0051] In this specific embodiment, the filter screen has an 8-layer structure (50 mesh / 80 mesh / 150 mesh / 500 mesh / 500 mesh / 150 mesh / 80 mesh / 50 mesh), the melt pump is 260-290℃ and the rotation speed is 45rpm, the mold temperature is 260-290℃, and the three-roll calender is 110-130℃.

[0052] Furthermore, a vision inspection system based on machine learning algorithms is used to monitor the surface defects and fluorescence uniformity of the thin film online; the system performs the following steps:

[0053] Image data of the thin film surface is acquired in real time using a high-speed linear CCD camera;

[0054] Image data is transmitted to an industrial control computer, where a pre-trained deep learning convolutional neural network (CNN) model is used to perform real-time analysis of the image.

[0055] The CNN model identifies bright spots, stripes, bubble defects, and fluorescence intensity distribution in the image;

[0056] If a defect or fluorescence uniformity exceeds a preset threshold, the system will automatically alarm and record the defect location information, while simultaneously feeding the signal back to the central control system. The central control system will adaptively fine-tune the extruder temperature, screw speed, or the roll gap and temperature of the three-roll calender according to the algorithm model.

[0057] The training data for the CNN model includes thousands of images of qualified and unqualified films with various annotations, which are trained through supervised learning. The adaptive fine-tuning algorithm of the central control system is either a PID control algorithm or a fuzzy control algorithm.

[0058] In the step of "discharging high-concentration light stabilizer masterbatch into a heated mixing tank, drying it at 80°C for 4 hours, mixing it with 90 parts of PC resin through a mixer, feeding it to an extruder, and preparing PC film through an extrusion casting machine",

[0059] The concentration of light stabilizer in the final mixture is detected in real time using an online near-infrared spectroscopy (NIR) analyzer; the system performs the following steps:

[0060] The NIR probe is used to continuously scan the material flow falling in the mixer;

[0061] Spectral data were collected and the concentration of the light stabilizer was calculated in real time using a partial least squares (PLS) regression algorithm;

[0062] The calculation results are compared with the preset target value. If the deviation exceeds ±5%, the rotation speed of the masterbatch feeder is automatically controlled to achieve closed-loop control of the concentration.

[0063] After the low-fluorescence PC card laser-sensitive film is prepared, a quality assessment is performed, including the following steps:

[0064] The fluorescence intensity of the thin film under 365nm ultraviolet light excitation was measured using a spectrophotometer and was required to be below a set threshold X.

[0065] A laser marking machine with a wavelength of 1064nm is used to mark the surface of the film. A machine vision system is used to identify the contrast of the marked area, which is required to be higher than a set threshold Y.

[0066] A quality score Q is calculated by combining the fluorescence intensity value I and the laser contrast value C using a comprehensive quality scoring function. When Q is greater than or equal to the standard value, the batch of film is judged to be qualified.

[0067] First embodiment:

[0068] In this embodiment, the raw materials included are shown in Table 1:

[0069] Table 1

[0070] PC resin 100 copies UV-1577 0.001 copies AM-101 (2,2'-Thiobis(4-tert-octylphenoxy)nickel) 0.0002 copies Molybdenum sulfide 0.001 copies

[0071] Second embodiment:

[0072] In this embodiment, the raw materials included are shown in Table 2:

[0073] Table 2

[0074] PC resin 100 copies UV-1164 0.001 copies NBC(N,N-di-n-butyldithiocarbamate) 0.0002 copies Molybdenum sulfide 0.001 copies

[0075] Third embodiment:

[0076] In this embodiment, the raw materials included are shown in Table 3:

[0077] Table 3

[0078] PC resin 100 copies UV-400 0.001 copies NBC(N,N-di-n-butyldithiocarbamate) 0.0005 copies Molybdenum sulfide 0.001 copies

[0079] Fourth embodiment:

[0080] In this embodiment, the raw materials included are shown in Table 4:

[0081] Table 4

[0082] PC resin 100 copies UV-1577 0.008 copies AM-101 (2,2'-Thiobis(4-tert-octylphenoxy)nickel) 0.001 copies Molybdenum sulfide 0.001 copies

[0083] Using the low-fluorescence PC laser-sensitive film for ID cards and its preparation method in this embodiment, firstly, 10 parts of PC resin are processed into 200-mesh PC powder using a grinding mill. The PC powder, triazine light stabilizer, nickel complex, and laser photosensitizer are mixed at high speed for 10 minutes at 400 rpm using a high-speed mixer, then cooled at low speed to below 60°C and discharged into a feeding hopper to obtain a mixture. The mixture is then fed to a twin-screw extruder via a feeding screw to obtain a high-concentration light stabilizer masterbatch. The high-concentration light stabilizer masterbatch is discharged into a heated mixing tank and dried at 80°C for 4 hours, and then mixed with 90 parts of PC resin using a mixer. The mixture is then fed to an extruder and a PC film is prepared using an extrusion casting machine. The PC film is then cooled and shaped using a melt filter, melt pump, mold, and three-roll calender to obtain a uniformly dispersed low-fluorescence PC film.

[0084] This invention utilizes a combination of triazine light stabilizers and a small amount of nickel complex to obtain a low-fluorescence PC card film;

[0085] This invention uses a grinding process to combine PC resin with powder light stabilizer and laser photosensitizer, so that the light stabilizer and laser photosensitizer are uniformly dispersed in high viscosity resin.

[0086] The PC film obtained by this invention, through the absorption of ultraviolet light by triazine light stabilizers and nickel complexes, has an ultraviolet transmittance between 4% and 10%, which will not affect the display effect of the underlying ultraviolet anti-counterfeiting ink and laser graphics.

[0087] This invention can reduce the influence of nickel complexes on the color of transparent films.

[0088] The molybdenum sulfide laser photosensitizer film prepared by this invention can achieve 256 gray levels of infrared laser etching.

[0089] This approach solves the technical problem in existing technologies where thin film materials cannot effectively suppress background fluorescence under ultraviolet light conditions while maintaining the excellent mechanical and optical properties of polycarbonate, without introducing color interference or reducing transparency.

[0090] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A low-fluorescence PC card laser-sensitive film, characterized in that, It includes 100 parts PC resin, 0.001-0.008 parts triazine light stabilizer, 0.0002-0.001 parts nickel complex and 0.001 parts laser photosensitizer.

2. The low-fluorescence PC card laser-sensitive thin film as described in claim 1, characterized in that, The triazine light stabilizer is one of UV-1577, UV-1164, and UV-400, and the nickel complex is one of AM-101 (2,2'-thiobis(4-tert-octylphenoloxy)nickel) and NBC (N,N-di-n-butyldithiocarbamate nickel).

3. The low-fluorescence PC card laser-sensitive thin film as described in claim 2, characterized in that, The laser photosensitizer is molybdenum sulfide with a particle size of 10 nm, a purity of 99.99%, and a specific surface area of ​​15 m². 2 / g.

4. A method for preparing a low-fluorescence PC card laser-sensitive film, used to prepare the low-fluorescence PC card laser-sensitive film as described in claim 3, characterized in that, Includes the following steps: Process 10 parts of PC resin into 200-mesh PC powder using a grinding mill according to the specified ratio; PC powder, triazine light stabilizer, nickel complex, and laser photosensitizer are first stirred at high speed for 10 minutes at 400 rpm in a high-speed mixer, then cooled at low speed to below 60°C, and discharged into the feed hopper to obtain a mixture. The mixture is fed to a twin-screw granulator via a feed screw to obtain high-concentration light stabilizer masterbatch. High-concentration light stabilizer masterbatch was discharged into a heated mixing tank and dried at 80°C for 4 hours. It was then mixed with 90 parts of PC resin through a mixer and fed to an extruder. PC film was prepared by an extrusion casting machine. The PC film is cooled and shaped by passing it through a melt filter, melt pump, mold, and three-roll calender to obtain a uniformly dispersed low-fluorescence PC film.

5. The method for preparing the low-fluorescence PC card laser-sensitive thin film as described in claim 4, characterized in that, In the step "the mixture is fed to a twin-screw granulator via a feed screw to obtain a high-concentration light stabilizer masterbatch": The twin-screw granulator has an aspect ratio of 45:1, and the process temperatures are 240-260℃ for the extruder, 250-270℃ for the filter, and 260-270℃ for the extruder head. The filter screen is a 3-layer 400-mesh metal mesh.

6. The method for preparing the low-fluorescence PC card laser-sensitive thin film as described in claim 5, characterized in that, In the step "cooling and shaping the PC film through a melt filter, melt pump, mold, and three-roll calender to obtain a uniformly dispersed low-fluorescence PC film": The filter screen has an 8-layer structure (50 mesh / 80 mesh / 150 mesh / 500 mesh / 500 mesh / 150 mesh / 80 mesh / 50 mesh), the melt pump is 260-290℃ and the speed is 45rpm, the mold temperature is 260-290℃, and the three-roll calender is 110-130℃.

7. The method for preparing the low-fluorescence PC card laser-sensitive thin film as described in claim 6, characterized in that, In the step "cooling and shaping the PC film through a melt filter, melt pump, mold, and three-roll calender to obtain a uniformly dispersed low-fluorescence PC film": A vision inspection system based on machine learning algorithms is used to monitor the surface defects and fluorescence uniformity of the thin film online; the system performs the following steps: Image data of the thin film surface is acquired in real time using a high-speed linear CCD camera; Image data is transmitted to an industrial control computer, where a pre-trained deep learning convolutional neural network (CNN) model is used to perform real-time analysis of the images. The CNN model identifies bright spots, stripes, bubble defects, and fluorescence intensity distribution in the image; If a defect or fluorescence uniformity exceeds a preset threshold, the system will automatically alarm and record the defect location information, while simultaneously feeding the signal back to the central control system. The central control system will adaptively fine-tune the extruder temperature, screw speed, or the roll gap and temperature of the three-roll calender according to the algorithm model.

8. The method for preparing the low-fluorescence PC card laser-sensitive thin film as described in claim 7, characterized in that, The training data for the CNN model includes thousands of images of qualified and unqualified films with various annotations, which are trained through supervised learning. The adaptive fine-tuning algorithm of the central control system is either a PID control algorithm or a fuzzy control algorithm.

Images