A process and method for preparing 3D nano-images and laser holographic images using cross-linked membranes

Abstract

This invention relates to the field of laser holographic image manufacturing technology, and particularly to a process and method for preparing 3D nano-image laser holographic images using cross-linked films, comprising the following steps: unwinding; printing alignment marks; printing binder and overprinting alignment; printing a UV imaging layer and curing; and rewinding. This application achieves high-precision overprinting alignment on transparent films. By pre-printing colored alignment marks on the surface of the cross-linked film, the difficult-to-identify transparent film is transformed into an identifiable material with a clear visual reference. A method of real-time comparison between the mark signal and the printing plate phase signal is used to perform dynamic overprinting alignment while printing the binder. The printing plate speed is adjusted in real time according to the deviation, achieving parallel and coordinated control of binder printing and overprinting alignment. This ensures that the printing position of the binder layer always dynamically coincides with the mark reference, solving the problem of difficult signal acquisition on transparent films and improving overprinting accuracy.

Description

Technical Field

[0001] This invention relates to the field of laser holographic image manufacturing technology, and in particular to a process and method for preparing cross-linked film 3D nano-image laser holographic images. Background Technology

[0002] Laser holographic images and 3D nanostructure images are widely used in product packaging, anti-counterfeiting labels, document sleeves, and decorative materials due to their unique optical visual effects and difficult-to-replicate anti-counterfeiting properties. With increasingly stringent anti-counterfeiting requirements, the market demand for high-precision, high-definition 3D nanostructure images fabricated on transparent thin-film materials is growing rapidly.

[0003] Currently, a common method for fabricating 3D nanoimages on flexible thin film materials is a continuous production process combining flexographic printing and UV imprinting. This involves coating a UV-curable resin onto the film surface, then imprinting the resin layer using a mold with micro / nanostructures etched on its surface, while simultaneously curing the resin under UV light, thus replicating the 3D pattern from the mold onto the film surface. However, because the cross-linked film itself is transparent or translucent, and the subsequently coated UV imaging layer is also transparent, traditional photoelectric registration methods struggle to capture stable and clear signals on transparent materials. This results in the inability to precisely control the relative positions of the patterns between layers during multi-stage continuous production, easily leading to registration deviations that affect the final product's visual appeal and anti-counterfeiting performance. Summary of the Invention

[0004] To overcome the shortcomings of the problems mentioned in the background, this application provides a process and method for preparing 3D nano-image laser holographic images of cross-linked films.

[0005] The technical solution is as follows: a process and method for preparing 3D nano-image laser holographic images using cross-linked films, comprising the following steps: S1. Unwind; S2, Printing alignment cursor; S3. Print the adhesive and align the printing plates; S4, Printing UV Imaging Layer and Curing; S5. Roll up.

[0006] Furthermore, in step S2, a colored alignment mark with high optical contrast is printed on the surface of the unwound cross-linked film.

[0007] Furthermore, in step S3, during the printing of the binder, the amount of binder transferred to the surface of the cross-linked film is adjusted so that the binder forms a uniform coating on the cross-linked film. At the same time, the alignment cursor signal on the cross-linked film is captured in real time to generate a first wave curve. The circumferential phase of the binder printing plate axis is detected in real time to generate a second wave curve. The control system compares the feature points of the first wave curve with the feature points of the second wave curve and adjusts the rotation speed of the printing plate axis to ensure accurate registration and alignment.

[0008] Furthermore, the characteristic points of the first wave curve are peak points, and the characteristic points of the second wave curve are reference mark points of the printing plate axis dial.

[0009] Furthermore, the specific method of overprinting alignment in step S3 is as follows: The control system compares the peak point of the first wave curve with the peak point of the second wave curve in phase, calculates the instantaneous deviation value Δφ between them, and when Δφ exceeds the preset overprinting tolerance threshold, it calculates the compensation amount according to the PLC control algorithm and drives the overprinting alignment actuator to adjust the position of the printing plate axis in real time, so that the printing area of ​​the subsequent printing process always dynamically coincides with the alignment cursor reference.

[0010] Furthermore, the specific method for printing and curing the UV imaging layer in step S4 is as follows: A graded transfer control is implemented for the UV adhesive to adjust the amount of UV adhesive transferred to the surface of the crosslinked film, so that the UV adhesive forms a uniform coating. At the embossing station, an embossing mold with a 3D nanostructure pattern on its surface is used to apply pressure to a cross-linked film coated with UV adhesive. At the same time, a UV light source is used to irradiate and cure the UV adhesive under pressure, thus replicating the three-dimensional pattern on the surface of the embossing mold onto the UV adhesive layer, forming a 3D nano image on the cross-linked film.

[0011] Furthermore, in step S4, during the imprinting and curing process, a constant-temperature cooling medium is introduced into the imprinting mold to control its temperature and prevent thermal deformation of the cross-linked film.

[0012] Furthermore, between steps S3 and S4, a tension adjustment step is also included. By changing the transport path length of the crosslinked film, the process deviation between the preceding and following stations is compensated, ensuring that the crosslinked film enters the imprinting station with a stable tension.

[0013] Furthermore, the UV light source in step S4 is an LED lamp, which is located directly above the imprinting mold and is used to instantly cure the UV adhesive during imprinting.

[0014] Furthermore, the temperature of the constant-temperature cooling medium is controlled between 18°C ​​and 25°C.

[0015] Beneficial effects: First, it achieves high-precision registration on transparent films. By pre-printing colored registration marks on the surface of the cross-linked film, the difficult-to-identify transparent film is transformed into an identifiable material with a clear visual reference. By using a method of real-time comparison between the mark signal and the phase signal of the printing plate, dynamic registration is performed while printing the binder. The printing plate speed is adjusted in real time according to the deviation, realizing parallel and coordinated control of the printing binder and the registration. This ensures that the printing position of the binder layer always dynamically coincides with the mark reference, solving the problem of difficult signal acquisition on transparent films and improving the registration accuracy.

[0016] Secondly, a graded transfer control method is adopted for the coating process of the binder and UV adhesive. In the binder printing step, by adjusting various parameters during the transfer process, a uniform and defect-free coating of binder is formed on the cross-linked film. In the UV imaging layer coating step, through three-level control—coarse adjustment of the immersion depth, multi-dimensional fine adjustment of the doctor blade, and coordinated adjustment of the transfer pressure—uniform and controllable coating of the binder and UV imaging layer is achieved, effectively solving problems such as uneven adhesive layer thickness and air bubble incorporation in traditional coating processes.

[0017] Third, a constant-temperature cooling method is used to control the temperature of the embossing mold during the imprinting and curing steps. By circulating a cooling medium at a constant temperature inside the mold, the frictional heat generated during imprinting and the polymerization heat released during UV adhesive curing are continuously removed, ensuring the mold temperature remains within a set stable range. This effectively prevents pattern distortion caused by thermal expansion of the mold, avoids damage to registration accuracy due to thermal expansion, and also prevents the UV adhesive from partially curing before filling the mold due to excessively high temperatures.

[0018] Fourth, by adding a tension adjustment step between the printing binder step and the printing UV imaging layer step, the macroscopic path deviation caused by changing the transmission path length of the crosslinked film in this section is compensated for by changing the printing mold or adjusting the process parameters. The tension fluctuation between the front and back stations is absorbed, so that the film material enters the printing station with the best entry angle and stable tension. This achieves a flexible transition and buffer compensation between the front and back processes, effectively avoiding the cumulative error between processes. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0020] The above-described solution will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. The implementation conditions used in the embodiments may be further adjusted according to the conditions of specific manufacturers, and the implementation conditions not specified are generally those in routine experiments.

[0021] like Figure 1 As shown, a process and method for preparing 3D nano-image laser holographic images using cross-linked films includes the following steps: S1. Unwinding: Unwind the rolled cross-linked film substrate and transmit it forward with a preset constant tension. During the transmission process, the film material is kept flat and wrinkle-free through tension control methods to provide a stable substrate input for subsequent steps. The unwinding tension is set and adjusted according to the characteristics of the film material to ensure that the film material is neither loose nor overstretched during the transmission process. S2. Printing alignment marks: On the surface of the unwound cross-linked film, a colored alignment mark with high optical contrast is printed at a preset position. This colored alignment mark serves as the spatial position reference for all subsequent steps. Its shape, size and spacing are pre-designed according to product requirements. The mark is printed with ink that is significantly different in color from the cross-linked film to ensure that it can be accurately identified in subsequent steps. S3. Printing Adhesive and Registration: A layer of adhesive is printed onto the cross-linked film surface with the registration marks. The adhesive enhances the adhesion between the subsequent UV imaging layer and the cross-linked film substrate. Simultaneously, the position of the registration marks on the cross-linked film is monitored in real time, as is the rotation phase of the printing roller. The mark position signal is compared with the roller phase signal, and the roller speed or phase is adjusted in real time based on the comparison result to ensure precise alignment between the adhesive printing position and the mark reference. This process combines adhesive coating and registration in a single, parallel step. S4. Printing and Curing the UV Imaging Layer: On the surface of the cross-linked film with the binder already printed and aligned, a UV-curable resin is coated to form a UV imaging layer. Subsequently, an imprinting mold with a 3D nanostructure pattern on its surface is brought into contact with the cross-linked film coated with the UV imaging layer, and pressure is applied to fill the micro-nano structure of the mold with UV resin. While maintaining pressure, a UV light source is used to irradiate the mold, causing the UV resin to cure instantly in the filled state, replicating the three-dimensional pattern on the mold surface onto the UV adhesive layer to form a 3D nano-image. This step integrates coating, imprinting, and curing into one process. S5. Rewinding: The cross-linked film that has been imprinted and cured is rewound into a roll under constant tension control to obtain the finished product.

[0022] In step S2, colored alignment marks with high optical contrast are printed on the unwound cross-linked film surface. At specific locations on the cross-linked film surface, colored marks with regular shapes and clear boundaries are printed using ink that contrasts sharply with the film material color. The mark color can be black, red, blue, etc., creating a strong contrast with the transparent film material. The mark shape can be square, triangular, or linear for easy subsequent identification. The spacing between the marks is predetermined according to product design requirements, serving as a positional reference throughout the process.

[0023] In step S3, during the printing of the binder, the amount of binder transferred to the surface of the cross-linked film is adjusted so that the binder forms a uniform coating on the cross-linked film. At the same time, the alignment cursor signal on the cross-linked film is captured in real time to generate a first wave curve. The circumferential phase of the binder printing plate axis is detected in real time to generate a second wave curve. The control system compares the feature points of the first wave curve with the feature points of the second wave curve and adjusts the rotation speed of the printing plate axis to ensure accurate registration and alignment.

[0024] During the cross-linking membrane transfer process, the membrane surface is scanned in real time using an optical detection method to capture the colored alignment cursor printed in step S2. Each time the cursor passes the detection point, a pulse signal is generated. As the membrane material is continuously transferred, these pulse signals are connected to form a wave-shaped curve. Each peak of this curve corresponds to the moment when the cursor passes through, reflecting the position sequence of the cursor on the membrane material.

[0025] As the printing plate used for the adhesive rotates, its circumferential position changes continuously. The scale marks on the plate are captured in real time using a detection method. Whenever the plate rotates to a specific angle, a pulse signal is generated. As the plate rotates continuously, these pulse signals are connected to form a wave-shaped curve. Each peak of this curve corresponds to the moment when the plate rotates to the reference position, reflecting the rotation phase of the plate.

[0026] Compare the first wave curve (cursor signal) and the second wave curve (plate axis phase signal) to observe whether the peaks of the two wave curves are aligned. If the peaks of the two wave curves are exactly aligned, it indicates that the rotation of the plate axis and the transfer of the film are synchronized, and the adhesive is printed in the correct position. If the peaks of the two curves are misaligned, it indicates that the plate axis is rotating too fast or too slow, causing the printing position to be off-center. When misalignment is found, calculate the amount of adjustment required based on the degree of misalignment (deviation value), and then adjust the rotation speed of the printing plate axis in real time to resynchronize the plate axis with the film until the peaks of the two curves are aligned again.

[0027] By simultaneously performing binder coating and cursor-plate axis dual signal comparison, parallel control of coating and overprinting was achieved. On the one hand, the uniformity of the binder layer was ensured; on the other hand, through real-time comparison and dynamic adjustment, the precise alignment of the binder printing position with the cursor reference was ensured, laying an accurate positional foundation for the subsequent UV imaging layer imprinting.

[0028] The characteristic point of the first wave curve is the peak point, and the characteristic point of the second wave curve is the reference mark point of the printing plate axis dial.

[0029] The specific method for overprinting alignment in step S3 is as follows: The control system compares the peak points of the first waveform with the peak points of the second waveform in phase, calculates the instantaneous deviation value Δφ between them, and when Δφ exceeds the preset overprinting tolerance threshold, it calculates the compensation amount according to the PLC control algorithm and drives the overprinting alignment actuator to adjust the position of the printing plate axis in real time, so that the printing area of ​​the subsequent printing process always dynamically coincides with the alignment cursor reference.

[0030] The specific method for printing and curing the UV imaging layer in step S4 is as follows: A graded transfer control system is implemented for the UV adhesive, adjusting the amount of UV adhesive transferred to the crosslinked film surface to ensure a uniform coating. The UV adhesive undergoes multiple transfers from its storage state to its final application on the film, each requiring precise control of the adhesive quantity. Graded control achieves uniformity in the final coating: The UV adhesive is transferred from storage to the first roller. By adjusting the transfer depth, the amount of base adhesive carried by the first roller is controlled. Coarse adjustment determines the approximate adhesive supply. The roller carrying the adhesive passes through a doctor blade, which performs fine adjustments from different directions (distance, angle, position) to scrape off excess adhesive from the roller surface, retaining only precisely measured adhesive. This fine adjustment ensures accurate adhesive quantity for the next stage. Accurately measured adhesive is transferred step-by-step from the first roller to the next, finally to the crosslinked film. During each transfer, the efficiency of adhesive transfer and the final adhesive layer thickness on the film are controlled by adjusting the contact degree between the rollers.

[0031] At the embossing station, an embossing mold with a 3D nanostructure pattern on its surface is used to apply pressure to a cross-linked film coated with UV adhesive. At the same time, a UV light source is used to irradiate and cure the UV adhesive under pressure, thus replicating the three-dimensional pattern on the surface of the embossing mold onto the UV adhesive layer, forming a 3D nano image on the cross-linked film.

[0032] An imprinting mold with a precisely etched 3D nanostructure pattern is brought into contact with a cross-linked film coated with UV adhesive, and pressure is applied. Under pressure, the liquid UV adhesive is squeezed into every tiny depression on the mold surface, forming a textured shape complementary to the mold pattern. While maintaining pressure, a UV light source is used for irradiation. The UV adhesive undergoes a chemical reaction upon exposure to light, changing from a liquid to a solid state, fixing the textured shape formed earlier. After curing, the cross-linked film is separated from the mold. At this point, a 3D nanostructure opposite to the pattern on the mold surface has formed on the UV adhesive layer. This structure interferes with, diffracts, and reflects light, exhibiting a laser holographic effect. Through hierarchical transfer control technology, precise metering and uniform coating of the UV adhesive from storage to application are achieved. By simultaneously performing imprinting and curing, curing is completed the instant the UV adhesive completely fills the mold structure, faithfully replicating the 3D nanopattern onto the cross-linked film, providing excellent optical effects for the final product.

[0033] In step S4, during the imprinting and curing process, a constant-temperature cooling medium is introduced into the imprinting mold to control its temperature and prevent thermal deformation of the cross-linked film. The temperature of the constant-temperature cooling medium is controlled between 18°C ​​and 25°C.

[0034] During the imprinting and curing process, frictional heat is generated between the mold and the film material. The UV adhesive, due to excessively high temperature, partially cures before filling the mold, resulting in pattern defects. By incorporating channels for cooling medium flow inside the imprinting mold, a constant-temperature cooling medium is continuously introduced into these channels during imprinting and curing. As the cooling medium flows through the mold, it carries away the heat absorbed by the mold, keeping the mold temperature consistently within the set range. By introducing a constant-temperature cooling medium into the imprinting mold, the heat generated during imprinting and curing is effectively counteracted, maintaining mold temperature stability. This prevents pattern distortion and misregistration caused by thermal expansion, avoids pre-curing of the UV adhesive, and ensures stability for long-term continuous production. By controlling the cooling medium temperature within the preferred range of 18°C-25°C, an optimal thermally stable environment is provided for the imprinting and curing process.

[0035] Between steps S3 and S4, there is also a tension adjustment step, which compensates for the process deviation between the front and back stations by changing the transport path length of the crosslinked film, ensuring that the crosslinked film enters the imprinting station with a stable tension.

[0036] When different sizes of imprinting dies are used, the path length of the film material at the imprinting station will change, and the tension requirements of the preceding and following stations may differ, resulting in unstable tension of the film material in the transition zone. After long-term operation, the film material transmission path may slightly deviate. By setting a floating roller in the transition zone between S3 and S4, the film material is transported around the floating roller. By changing the height of the floating roller, the path length of the film material in this section can be changed. Moving the floating roller downwards lengthens the path of the film material in this section, while increasing the contact angle between the film material and the guide roller. Moving the floating roller upwards shortens the path of the film material in this section, while decreasing the contact angle. Therefore, when the path length at the imprinting station changes, adjusting the floating roller compensates for this change, keeping the overall path of the film material stable. This ensures that the film material enters the imprinting station at the optimal angle, guarantees uniform pressure distribution, and absorbs the tension differences between the preceding and following stations, allowing the film material to enter the imprinting station with a smooth and constant tension.

[0037] In step S4, the UV light source is an LED lamp, located directly above the imprinting mold, used to instantly cure the UV adhesive during imprinting. The LED lamp reaches maximum brightness instantly upon activation, requiring no preheating time. The emitted light is concentrated at a specific wavelength, with no excess infrared radiation. By installing the LED lamp directly above the imprinting mold, facing the imprinting point, the illumination distance is minimized, resulting in the strongest light reaching the imprinting point and maximizing efficiency. The vertical illumination prevents shadows, ensuring uniform illumination of all parts of the UV adhesive. This ensures the UV adhesive is irradiated the instant it fills the mold. This application achieves precise synchronization between imprinting and curing by using an LED lamp as the UV light source and positioning it directly above the imprinting mold.

[0038] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, all equivalent changes made to the content described in the claims of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A process and method for the preparation of laser holographic images of crosslinked membranes 3D nanomaps, characterized by, Includes the following steps: S1. Unwind; S2, Printing alignment cursor; S3. Print the binder and align the printing plates; S4, Printing UV Imaging Layer and Curing; S5. Roll up.

2. The process and method for preparing 3D nano-image laser holographic images using cross-linked films according to claim 1, characterized in that, In step S2, a colored alignment mark with high optical contrast is printed on the surface of the unwound cross-linked film.

3. The process and method for preparing a cross-linked film 3D nano-image laser holographic image according to claim 1, characterized in that, In step S3, when printing the binder, the amount of binder transferred to the surface of the cross-linked film is adjusted so that the binder forms a uniform coating on the cross-linked film. At the same time, the alignment cursor signal on the cross-linked film is captured in real time to generate a first wave curve. The circumferential phase of the binder printing plate axis is detected in real time to generate a second wave curve. The control system compares the feature points of the first wave curve with the feature points of the second wave curve and adjusts the rotation speed of the printing plate axis to ensure accurate registration and alignment.

4. The process and method for preparing a cross-linked film 3D nano-image laser holographic image according to claim 3, characterized in that, The characteristic point of the first wave curve is the peak point, and the characteristic point of the second wave curve is the reference mark point of the printing plate axis scale.

5. The process and method for preparing a cross-linked membrane 3D nano-image laser holographic image according to claim 4, characterized in that, The specific method for overprinting alignment in step S3 is as follows: The control system compares the peak point of the first wave curve with the peak point of the second wave curve in phase, calculates the instantaneous deviation value Δφ between them, and calculates the compensation amount according to the control algorithm when Δφ exceeds the preset overprinting tolerance threshold. The control system then drives the actuator to adjust the position of the printing plate axis in real time, so that the printing area of ​​the subsequent printing process always dynamically coincides with the alignment cursor reference.

6. The process and method for preparing a cross-linked membrane 3D nano-image laser holographic image according to claim 5, characterized in that, The specific method for printing and curing the UV imaging layer in step S4 is as follows: A graded transfer control is implemented for the UV adhesive to adjust the amount of UV adhesive transferred to the surface of the crosslinked film, so that the UV adhesive forms a uniform coating. At the embossing station, an embossing mold with a 3D nanostructure pattern on its surface is used to apply pressure to a cross-linked film coated with UV adhesive. At the same time, a UV light source is used to irradiate and cure the UV adhesive under pressure, thus replicating the three-dimensional pattern on the surface of the embossing mold onto the UV adhesive layer, forming a 3D nano image on the cross-linked film.

7. The process and method for preparing a cross-linked film 3D nano-image laser holographic image according to claim 3, characterized in that, In step S4, during the imprinting and curing process, a constant-temperature cooling medium is introduced into the imprinting mold to control its temperature and prevent thermal deformation of the cross-linked film.

8. The process and method for preparing 3D nano-image laser holographic images using cross-linked films according to claim 1, characterized in that, Between steps S3 and S4, a tension adjustment step is also included. By changing the transport path length of the crosslinked film, the process deviation between the preceding and following stations is compensated, ensuring that the crosslinked film enters the imprinting station with a stable tension.

9. The process and method for preparing a cross-linked film 3D nano-image laser holographic image according to claim 7, characterized in that, The UV light source in step S4 is an LED lamp, which is located directly above the imprinting mold and is used to instantly cure the UV adhesive during imprinting.

10. The process and method for preparing a cross-linked film 3D nano-image laser holographic image according to claim 7, characterized in that, The temperature of the constant-temperature cooling medium is controlled between 18°C ​​and 25°C.

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