Optical security element with intersecting micro-relief relief structures, product and method of manufacture

Abstract

The present application relates to a kind of optical anti-counterfeiting elements of intersecting micro-relief three-dimensional structure, product and preparation method, the preparation method includes: S1.making micro-relief three-dimensional structure array, so that the fixed point of micrograph array and microlens array substantially coincides, then synthesis superposition, obtain intersecting micro-relief three-dimensional structure array, and generate corresponding micro-relief photoetching file;S2.preparing metal nickel plate;S3.preparing composite mold metal nickel plate;S4.preparing optical anti-counterfeiting film;S5.making reflective medium layer: the surface of the micro-relief three-dimensional structure array layer of the optical anti-counterfeiting film prepared in S4 is provided with reflective medium layer.The present application reduces production difficulty, simplifies technological process, and the quality of optical anti-counterfeiting element is more stable.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of optical anti-counterfeiting technology, and particularly relates to an optical anti-counterfeiting element with intersecting micro-relief three-dimensional structures, a product and a preparation method. BACKGROUND

[0002] With the rapid development of market economy, the requirements for the performance form, content and anti-counterfeiting effect of high-end product packaging are increasingly high. Compared with commonly used packaging materials, dynamic and three-dimensional display anti-counterfeiting packaging materials have attracted high attention in the industry and achieved significant breakthroughs due to their advantages such as good anti-counterfeiting effect, high difficulty in imitation, good visual effect and the like.

[0003] Among them, the microlens array imaging technology, as a main technical classification of three-dimensional display, becomes a novel public anti-counterfeiting technology beyond traditional optical images due to its naked-eye viewing and angle freedom. The microlens array anti-counterfeiting film is a film surface with a microlens array and a matching micro-text array. Through the integrated imaging effect of the microlens array on the micro-text array, strong dynamic, three-dimensional, transformation and other effects are formed, including floating, sinking, parallel motion, orthogonal motion, double-channel and the like. It has horizontal and vertical parallax, free viewing angle, and the observer can see the three-dimensional text without any special observation equipment or skills. Moreover, the technical threshold of this technology is high, the micro-text cannot be obtained by traditional copying methods, and the anti-counterfeiting effect is good.

[0004] The necessary three elements of the existing microlens array imaging technology are: microlens array, transparent base film and micro-text array with similar micro-lens. The transparent base film with a certain thickness can focus the lens focal point to the micro-text array layer, so as to present clear and dynamic text by using the moire magnification principle. For example, the moire magnifiers with microlens array and text array structure on the same side of the base film or on the double sides of the base film are disclosed in patent documents such as CN101563640, CN101443692, CN101120139, CN101346244, US5712731, US0034082, US4765656, US4892336, CN105313529, CN1271106 and CN101563640. However, the applicant found that the moire magnifiers in these patent documents have the following defects:

[0005] 1. The design cycle error of the microlens array and the micro-text array is in the sub-micron level, and the precision requirement is extremely high, which makes the production difficulty too high;

[0006] 2. In the production process, the microlens array and the text array need to be processed respectively, resulting in a complex process flow;

[0007] 3. In order to meet imaging requirements, the existing processing method requires the micro-images to be located within the focal length range of the microlens, thus requiring a thick base film to meet the focal length requirement. In order to avoid misalignment and pattern deformation caused by deformation difference between two processing steps, the existing processing method requires increasing the thickness of the substrate to increase the rigidity of the overall structure, which is costly. Summary of the Invention

[0008] In order to overcome the shortcomings of the prior art, one objective of the present invention is to provide an optical anti-counterfeiting element that can provide a unique 3D visual effect and has low production cost; another objective is to provide a method for preparing the optical anti-counterfeiting element, which reduces the difficulty of production, simplifies the process, and further reduces costs; and yet another objective is to provide at least one product that uses the optical anti-counterfeiting element.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for preparing an optical anti-counterfeiting element with an intersecting micro-relief three-dimensional structure, comprising:

[0011] S1. Fabrication of a micro-relief three-dimensional structure array: Design a micro-image array and a microlens array, perform spatial three-dimensional architecture modulation on the micro-image array and the microlens array so that the fixed points of the micro-image array and the microlens array coincide, and then synthesize and superimpose them to obtain an intersecting micro-relief three-dimensional structure array, and generate a micro-relief lithography file corresponding to the intersecting micro-relief three-dimensional structure array; the synthesis and superposition specifically involves: intersecting and superimposing the surface morphology and curvature of the micro-image array and the microlens array, so that the micro-image array is nested in the microlens array;

[0012] S2. Preparation of a nickel plate: The photosensitive adhesive layer on the photolithography glass is exposed and cleaned according to the micro-relief photolithography file generated in S1 to obtain a micro-relief three-dimensional structure array A recorded on the photosensitive adhesive layer. Then, chemical plating is performed on the surface of the micro-relief three-dimensional structure array A to form a conductive silver layer. Then, it is immersed in an electrolytic tank for electroplating to obtain a nickel plate.

[0013] S3. Preparation of composite mold nickel plate: The micro-relief three-dimensional structure array A on the nickel plate is replicated using an embossing method, and array A is combined with other components according to packaging design requirements. Holographic laser junction The components are combined and arranged to obtain a composite mold with a micro-relief three-dimensional structure array B. Then, chemical plating is performed on the surface of the micro-relief three-dimensional structure array B to form a conductive silver layer. Then, it is immersed in an electrolytic tank for electroplating to obtain a composite mold metal nickel plate.

[0014] S4. Preparing an optical anti-counterfeiting film: copying the micro-relief three-dimensional structure array B on the metal nickel plate of the composite mold obtained in S3 to one side surface of a substrate by a pressing method, and curing to form a micro-relief three-dimensional structure array layer on the one side surface of the substrate, thereby preparing the optical anti-counterfeiting film;

[0015] S5. Preparing a reflective medium layer: disposing a reflective medium layer on the surface of the micro-relief three-dimensional structure array layer of the optical anti-counterfeiting film prepared in S4.

[0016] Further, the structure line width of the micro-text array in the micro-relief three-dimensional structure array obtained in S1 is in the range of 500 nanometers to 50 micrometers, and the structure periods of the micro-text array and the microlens array are similar, and the magnification of the micro-text after imaging of the optical anti-counterfeiting element and the ratio of the period difference of the micro-text array and the microlens array should meet the following requirements:

[0017] Magnification M: wherein T L is the lens period, T p is the text period;

[0018] Lens curvature radius r: wherein h is the lens height, Φ L is the lens size;

[0019] Lens focal length f: wherein n is the refractive index;

[0020] Moiré image size H i :

[0021] Further, in S2, before exposure, further comprising: compensating the exposure energy according to the photosensitive adhesive layer to improve the generation quality of the surface curvature of the micro-text array and the microlens array in the micro-relief three-dimensional structure array A.

[0022] As a preferred, in S2, the thickness of the photosensitive adhesive layer is 3-10 micrometers, and the included angle between the boundary side wall of the intersection area of the micro-text array and the microlens array in the micro-relief three-dimensional structure array A and the photosensitive adhesive layer is ≥60 degrees.

[0023] As a preferred, the surface curve height of the micro-text array is about 1 / 2 of the height of the microlens array.

[0024] Further, the exposure in S2 is one-time exposure to make the micro-text array and the microlens array of the micro-relief three-dimensional structure array A, or two-time exposure to make the microlens array and the micro-text array of the micro-relief three-dimensional structure array A respectively.

[0025] In some embodiments, the substrate described in S4 is a substrate with an adhesion-enhancing layer, and in S5, the surface of the micro-relief three-dimensional structure array layer is simultaneously subjected to strong corona treatment.

[0026] In other embodiments, the substrate in S4 is a release substrate, and in S5, the surface of the micro-relief three-dimensional structure array layer is simultaneously subjected to strong corona treatment.

[0027] In other embodiments, the substrate in S4 is the substrate of the adhesion enhancement layer, and the surface of the micro-relief three-dimensional structure array layer is not treated in S5.

[0028] An optical anti-counterfeiting element with an intersecting micro-relief three-dimensional structure includes:

[0029] The substrate is a transparent or translucent sheet material;

[0030] A micro-relief three-dimensional structure layer is disposed on the lower surface of the substrate, comprising a microlens array structure and a micro-graphic array structure; the micro-relief three-dimensional structure layer is an intersecting micro-relief three-dimensional structure layer, the micro-graphic array structure is nested in the microlens array structure, and the microlens array structure has a through groove communicating with the micro-graphic array structure.

[0031] A reflective medium layer is placed on the lower surface of the micro-relief three-dimensional structure layer.

[0032] Preferably, the sidewalls of the through groove are perpendicular to the horizontal plane.

[0033] Optionally, the microlens array structure is a convex microlens array or a concave microlens array.

[0034] A product is laser paper, comprising paper and an optical anti-counterfeiting element, wherein the surface of the reflective medium layer of the optical anti-counterfeiting element is bonded to the paper.

[0035] A product is a laser composite paper, comprising paper and an optical anti-counterfeiting element prepared by the method of claim 7, wherein the surface of the reflective medium layer of the optical anti-counterfeiting element is bonded to the paper.

[0036] Another product is a full-transfer laser transfer paper with anti-counterfeiting elements, comprising paper and a micro-embossed three-dimensional structure layer and a reflective medium layer of optical anti-counterfeiting elements prepared by the method described in claim 8, wherein the substrate of the optical anti-counterfeiting elements is mechanically peeled off, and the surface of the reflective medium layer is bonded to the paper; or, it is a medium laser transfer paper with a three-dimensional structure of anti-counterfeiting elements, comprising paper and a reflective medium layer of optical anti-counterfeiting elements, wherein the substrate of the optical anti-counterfeiting elements and the micro-embossed three-dimensional structure layer are mechanically peeled off, and the surface of the reflective medium layer is bonded to the paper.

[0037] In embodiments of the present invention, the adhesion-enhancing layer is a solvent-based surface energy-enhancing resin layer.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] 1. Reduced Production Difficulty: By designing micro-image arrays and microlens arrays separately, and then combining and superimposing them, an intersecting micro-relief three-dimensional structure array is obtained. A micro-relief photolithography file corresponding to the intersecting micro-relief three-dimensional structure array is generated before proceeding with plate making, imprinting, and other processes. Compared to existing technologies that involve creating microlenses and micro-images on two sides of the substrate separately, requiring two processing steps and causing deformation with each step, resulting in material loss, and requiring precise alignment of the micro-images and microlenses (within 50 micrometers for some effects), this invention effectively avoids these problems and reduces production difficulty.

[0040] 2. Simplified process flow: The image to be presented is deconstructed into a micro-image array, a microlens array is made, and then the micro-image array and the microlens array are synthesized by calculation, so that the surface morphology and curvature of the two are combined into a micro-relief three-dimensional microstructure, and then subsequent processing is carried out, so that two plate makings are reduced to one, two imprintings are reduced to one, and the double-sided reinforcement layer treatment of the substrate is reduced to a single side, thus simplifying the process flow.

[0041] 3. The imaging of this invention is a virtual image, so the focal length has no effect on the imaging. There is no deformation problem in one processing and no registration problem in one structure making, which makes the manufactured optical anti-counterfeiting element have high quality stability and high yield.

[0042] 4. The micro-image array and microlens array are superimposed in an intersecting manner, which enhances the stereoscopic visual effect of the components without increasing the thickness of the components. Attached Figure Description

[0043] Figure 1 This is a schematic flowchart of a method for preparing an optical anti-counterfeiting element according to the present invention;

[0044] Figure 2 This is a schematic diagram of the optical anti-counterfeiting element described in Embodiment 1 of the present invention;

[0045] Figure 3 This is a schematic diagram illustrating the principle of the preparation method of the optical anti-counterfeiting element according to Embodiment 1 of the present invention;

[0046] Figure 4 This is a detailed schematic diagram illustrating the principle of the preparation method of the optical anti-counterfeiting element described in Embodiment 1 of the present invention;

[0047] Figure 5This is a schematic diagram of the optical anti-counterfeiting element described in Embodiment 2 of the present invention;

[0048] Figure 6 This is a schematic diagram illustrating the principle of the preparation method of the optical anti-counterfeiting element described in Embodiment 2 of the present invention;

[0049] Figure 7 This is a detailed schematic diagram illustrating the principle of the preparation method of the optical anti-counterfeiting element described in Embodiment 2 of the present invention;

[0050] Figure 8 This is a top view partial schematic diagram and an upward visual effect diagram of the micro-relief three-dimensional structure array in the optical anti-counterfeiting element described in Embodiment 1 of the present invention;

[0051] Figure 9 This is a top view partial schematic diagram and a downward visual effect diagram of the micro-relief three-dimensional structure array in the optical anti-counterfeiting element described in Embodiment 1 of the present invention;

[0052] Figure 10 This is a top view partial schematic diagram and an upward visual effect diagram of the micro-relief three-dimensional structure array in the optical anti-counterfeiting element described in Embodiment 2 of the present invention;

[0053] Figure 11 This is a top view partial schematic diagram and a downward visual effect diagram of the micro-relief three-dimensional structure array in the optical anti-counterfeiting element described in Embodiment 2 of the present invention;

[0054] Figure 12 This is a schematic diagram of an embodiment of the optical anti-counterfeiting element of the present invention presenting a 3D dynamic visual effect;

[0055] Figure 13 This is a schematic diagram of an embodiment of the optical anti-counterfeiting element of the present invention presenting a multi-dimensional moving visual effect. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0057] like Figure 1 As shown, the method for preparing an optical anti-counterfeiting element according to the present invention includes:

[0058] S1. Fabrication of a micro-relief 3D structure array: First, design a micro-text array and a microlens array. Then, perform spatial 3D architecture modulation on the designed micro-text array and microlens array to ensure that the fixed points of the micro-text array and microlens array precisely coincide. After that, synthesize and superimpose to obtain a micro-relief 3D structure array and generate a micro-relief lithography file. The arrangement of the microlens array can be rectangular, hexagonal, circular, or randomly distributed. The arrangement of the micro-text array corresponds to the microlens array. The synthesis and superposition refers to intersection superposition (i.e., intersection superposition, where the surface morphology and curvature of the micro-text array and microlens array are intersected and superimposed, so that the micro-text array is nested in the microlens array, and synthesized to obtain a micro-relief 3D structure array file).

[0059] This step specifically includes the following:

[0060] The first step is to decompose the image (vector or bitmap file) to be presented into a micro-image array. At the same time, according to the designed parameters such as the period, crown height, aperture, and array (rectangular, hexagonal, circular, or randomly distributed) of the microlenses, a microlens array is fabricated. The period of the microlenses is between 30 micrometers and 100 micrometers, preferably 30 to 50 micrometers, and the crown height is between 2 micrometers and 9 micrometers, preferably 2 to 5 micrometers. The microlens array includes at least one of the following: spherical microlenses, ellipsoidal microlenses, cylindrical microlenses, and Fresnel lenses, preferably spherical microlenses.

[0061] The second step involves combining and superimposing the designed microlens array and microtext array in engineering software to generate a micro-relief lithography file. During superposition, the spatial three-dimensional structure of the two arrays can be modulated by software, and intersecting superposition can be selected. The microlens array can be either a convex microlens array or a concave microlens array, with convex microlens array and intersecting superposition being preferred. This is because the microtext array and microlens array are combined and superimposed in a computer. Using convex microlens array and intersecting superposition can ensure that the fixed points of the microtext array and microlens array are precisely aligned, with a much higher alignment accuracy than other fabrication methods.

[0062] Moreover, the structural linewidth of the micro-image array in the synthesized and superimposed micro-relief three-dimensional structure array is between 500 nanometers and 50 micrometers, and the structural period of the micro-image array is similar to that of the microlens array. At the same time, the ratio of the magnification of the micro-image array after imaging by the optical anti-counterfeiting element to the period difference between the micro-image array and the microlens array should meet the following requirements.

[0063] Magnification M: In the formula T L For the lens period, T p For the image and text cycle;

[0064] Lens curvature radius r: In the formula, h is the lens height, ΦL Lens size;

[0065] Lens focal length f: In the formula, n is the refractive index;

[0066] Moiré image size H i :

[0067] S2. Preparation of the nickel plate: First, the photosensitive adhesive layer on the photolithography glass is exposed and cleaned according to the micro-relief photolithography file generated in S1 to obtain the micro-relief three-dimensional structure array A recorded on the photosensitive adhesive layer. Then, chemical plating is performed on the surface of the micro-relief three-dimensional structure array A to form a conductive silver layer. Then, it is immersed in an electrolytic tank for electroplating to obtain the nickel plate. Specifically, the generated micro-relief photolithography file is loaded into a high-speed laser direct writing device to expose the photosensitive adhesive layer (photosensitive adhesive layer) on the positive photolithography glass. Then, the exposed photolithography glass is immersed in an alkaline developer to clean it and remove the photosensitive adhesive, obtaining the micro-relief three-dimensional structure array A recorded on the photosensitive adhesive layer. Then, a conductive silver layer is plated on the surface of the micro-relief three-dimensional structure array A using a chemical plating method (silver mirror reaction). Then, the photolithography glass with the conductive layer is immersed in an electrolytic tank as a cathode to obtain the nickel plate. Specifically, based on the structure of the micro-relief three-dimensional structure array in the micro-relief lithography file, the micro-image array and microlens array of the micro-relief three-dimensional structure array A can be fabricated using a single exposure, or the microlens array and micro-image array of the micro-relief three-dimensional structure array A can be fabricated sequentially using a second exposure.

[0068] S3. Preparation of composite mold nickel plate: First, the micro-relief three-dimensional structure array A on the nickel plate is replicated by imprinting. Then, other holographic laser structures are combined and arranged according to the packaging design requirements to obtain a composite mold of micro-relief three-dimensional structure array B. Then, chemical plating is performed on the surface of micro-relief three-dimensional structure array B on the composite mold to form a conductive silver layer. Then, it is immersed in an electrolytic tank for electroplating to obtain the composite mold nickel plate. Specifically, a conductive silver layer can be plated on the surface of micro-relief three-dimensional structure array B by chemical plating (silver mirror reaction). Then, a photolithographic glass with a conductive layer is immersed in an electrolytic tank as a cathode to obtain the composite mold nickel plate.

[0069] In one possible implementation, a micro-relief three-dimensional structure array A on a nickel plate is replicated on the surface of a 100-300 micrometer thick polyethylene terephthalate (PET) film or a 1 mm thick polycarbonate (PC) film using ultraviolet light curing nanoimprinting technology. A composite mold for the micro-relief three-dimensional structure array B is then prepared by combining and arranging holographic laser structures such as diffraction gratings, blazed gratings, sinusoidal reflection gratings, sawtooth gratings, and Fresnel lenses according to packaging design requirements. The arrangement and combination of the micro-relief three-dimensional structure array A and the holographic laser structures are highly flexible and diverse; multiple micro-relief three-dimensional structure arrays A can be combined with various micro / nano structures in different positions. A 188-micrometer thick PET film is preferred.

[0070] S4. Preparation of optical anti-counterfeiting film: The micro-relief three-dimensional structure array B on the composite mold metal nickel plate obtained in S3 is copied to one side surface of the substrate by imprinting method and cured to form a micro-relief three-dimensional structure array layer on one side surface of the substrate, thus obtaining an optical anti-counterfeiting film.

[0071] In one possible implementation, an optical anti-counterfeiting film is prepared using a rotary UV nanoimprinting method. Specifically, the micro-relief three-dimensional structure array B on the composite mold nickel plate made in S3 is copied onto a substrate with a thickness of 15-50 micrometers using a roll-to-roll nanoimprinting device. The material forming the undulating structure of the micro-relief layer needs to have the property that it can deform under certain temperature and pressure to form the required undulating structure, and then be able to be fixed after cooling and absorbing energy to maintain the three-dimensional structure of the micro-relief layer, thus obtaining an optical anti-counterfeiting film. The coating used in this step is a UV-curable coating, preferably a UV-curable coating based on acrylic resin, epoxy resin, or a mixture of both.

[0072] Of course, conventional hot pressing, molding, and EB electron beam curing methods can also be used, and thermoplastic coatings and electron beam EB curing coatings can be selected accordingly.

[0073] S5. Fabrication of a reflective medium layer: A reflective medium layer is set on the surface of the micro-relief three-dimensional structure array layer of the optical anti-counterfeiting film prepared in S4; specifically, the reflective medium layer is coated on the surface of the micro-relief three-dimensional structure array layer by means of coating, printing, deposition, etc.

[0074] Preferably, before exposure in S2, the exposure energy compensation is adjusted according to the photosensitive adhesive layer (the adjustment method is: first, the etching depth of the photosensitive adhesive layer is tested by using a linearly decreasing energy gradient ruler, and then a depth curve is generated based on the test results, and gain compensation is performed by comparing the difference between the two), so as to improve the generation quality of the surface curvature of the micro-image array and microlens array in the micro-relief three-dimensional structure array A.

[0075] Preferably, in step S2, the thickness of the photosensitive adhesive layer is 3-10 micrometers, and the angle between the boundary sidewall of the area where the micro-image array and the microlens array intersect (i.e., the through-slot 21 below) in the micro-relief three-dimensional structure array A and the photosensitive adhesive layer is ≥60 degrees. This design avoids the sidewall of the area where the micro-image array and the microlens array intersect in the photosensitive adhesive layer due to excessive energy absorption on the photoresist surface caused by poor matching between the positive photoresist and the exposure laser. This tilts the sidewall of the through-slot 21 in the micro-relief three-dimensional structure layer of the optical anti-counterfeiting element, preventing it from being perpendicular to the horizontal plane. Consequently, the optical anti-counterfeiting element suffers from excessive sidewall tilt, resulting in distortion and blurring of the micro-images, leading to unfavorable light diffraction and stray light.

[0076] Preferably, in step S1, the surface curve height of the micro-image array is approximately half the height of the microlens array, ensuring that the morphology of the microlens array and the micro-image array is as complete as possible within a limited photosensitive adhesive layer thickness, thereby improving the 3D visual effect.

[0077] like Figure 2 , 5 As shown, the optical anti-counterfeiting element prepared by the above method includes a substrate 1, a micro-relief three-dimensional structure layer 2, and a reflective medium layer 3.

[0078] in:

[0079] The substrate 1 is a transparent or semi-transparent sheet material, specifically a substrate with a thickness of 15-50 micrometers. The substrate can be at least partially transparent, or it can be a colored dielectric layer, or it can be a multilayer film formed by lamination. Moreover, the substrate is generally formed of a thin film material with good physical and chemical resistance and high mechanical strength, such as polyethylene terephthalate (PET) film, polyethylene naphthalate (PEN) film, and biaxially oriented polypropylene (BOPP) film, etc., preferably a 15-micrometer thick polyethylene terephthalate (PET) film.

[0080] The micro-relief three-dimensional structure layer 2 is disposed on the lower surface of the substrate 1 and includes a microlens array structure and a graphic array structure; wherein the microlens array structure can be a convex microlens array (see...). Figure 3 ) or concave microlens array (see Figure 6 Furthermore, the micro-relief three-dimensional structure layer 2 is an intersecting micro-relief three-dimensional structure layer (see...). Figure 3 The graphic array structure is nested in the microlens array structure, and a through groove 21 is formed on the microlens array structure to connect to the graphic array structure. The sidewall of the through groove 21 in the micro-relief three-dimensional structure layer is perpendicular to the horizontal plane (substrate 1), which is easy to process during photolithography.

[0081] The reflective medium layer 3 is disposed on the lower surface of the micro-relief three-dimensional structure layer 2. The reflective medium layer 3 may include any one or a combination of the following coatings: a single-layer metal coating; a multi-layer metal coating; a coating formed by sequentially stacking an absorption layer, a low-refractive-index medium layer, and a reflective layer, wherein the absorption layer is in contact with the surface of the micro-relief three-dimensional structure layer 2; a high-refractive-index medium layer coating; a multi-medium layer coating formed by sequentially stacking a first high-refractive-index medium layer, a low-refractive-index medium layer, and a second high-refractive-index medium layer, wherein the first high-refractive-index medium layer is in contact with the surface of the micro-relief three-dimensional structure layer 2; and a coating formed by sequentially stacking an absorption layer, a high-refractive-index medium layer, and a reflective layer, wherein the absorption layer is in contact with the surface of the micro-relief three-dimensional structure layer 2. The high-refractive-index dielectric layer, the first high-refractive-index dielectric layer, the low-refractive-index dielectric layer, and the second high-refractive-index dielectric layer are all dielectric layers with a refractive index greater than or equal to 1.7, and their materials can be one of ZnS, TiN, TiO2, TiO, Ti2O3, Ti3O5, Ta2O5, Nb2O5, CeO2, Bi2O3, Cr2O3, Fe2O3, HfO2, ZnO, etc. The low-refractive-index dielectric layer is a dielectric layer with a refractive index less than 1.7, and its material can be MgF2 or SiO2, etc. The materials of the metal coating and the reflective layer can be one of the metals or mixtures and alloys of Al, Cu, Ni, Cr, Ag, Fe, Sn, Au, Pt, etc., and the materials of the absorbent layer can be one of the metals or mixtures and alloys of Cr, Ni, Cu, Co, Ti, V, W, Sn, Si, Ge, etc. The material of the single-layer metal coating is preferably Al or ZnS.

[0082] The optical anti-counterfeiting element obtained by the above preparation method can provide unique 3D visual effects such as naked-eye 3D, dynamic 3D, and micro-text that can move in multiple dimensions: such as Figure 12 As shown, as the viewing angle moves, the micro-image stars of the optical anti-counterfeiting element exhibit a flashing dynamic visual effect, appearing and disappearing; and as... Figure 13 As shown, when the optical anti-counterfeiting element is observed from different perspectives, its micro-images A and B exhibit a visual effect of moving in different dimensions. On the other hand, since the refractive index of the optical anti-counterfeiting element is in the range of 1.3 to 1.7, the moiré amplifier has high imaging quality, and the micro-image layer array consists of multiple superimposed images with different periods, showing hierarchical differences in the moiré magnified image, i.e., moiré images with different depths of field, producing three-dimensional moiré images of floating, sinking, floating + sinking, floating interspersed with sinking, and sinking transitioning to floating.

[0083] The optical anti-counterfeiting element and its preparation method described in this invention will be further illustrated below through specific embodiments.

[0084] Example 1:

[0085] The method for preparing the intersecting micro-relief three-dimensional structure in this embodiment is as follows:

[0086] The image (vector or bitmap file) to be presented is decomposed into a micro-image array P. At the same time, based on the designed parameters such as the period, crown height, aperture, and array (rectangular, hexagonal, circular, random distribution) of the microlenses, a microlens array L (convex microlens array L+) is made.

[0087] Then, the microtext array P and the microlens array L are combined using an intersection superposition method to synthesize their surface morphology and curvature into a micro-relief three-dimensional microstructure N. The surface curve height of the microtext array P is approximately half the height of the convex microlens array L (see...). Figure 3 3a);

[0088] Then, using the rotary nanoimprinting method, the micro-relief three-dimensional microstructure array is replicated onto the substrate 1 by curing the coating layer 2, and a reflective medium layer 3 is placed on the surface of the micro-relief three-dimensional microstructure array (non-substrate connection surface) to obtain an optical anti-counterfeiting element.

[0089] Finally, the image of the moiré amplifier will be observed through the substrate 1 direction (see...). Figure 3 (3b in the middle).

[0090] Specifically, such as Figure 4 As shown:

[0091] The designed micro-image array P and convex microlens array L+ ​​are spatially modulated in a three-dimensional structure. The surface morphology and curvature of the micro-image array P and convex microlens array L+ ​​are synthesized using an intersection superposition method to obtain a micro-relief three-dimensional microstructure N. Then, the micro-relief three-dimensional microstructure N is recorded onto a photosensitive adhesive layer D on a photolithographic glass through exposure and development, forming a micro-relief three-dimensional structure array A on the photosensitive adhesive layer D. Chemical plating and electroplating are then performed to obtain a nickel plate F. Finally, the micro-relief three-dimensional structure array A on the nickel plate is replicated using an imprinting method. Based on the packaging design requirements, the holographic laser effect structure is combined and arranged to obtain a composite mold of micro-relief three-dimensional structure array B. Then, chemical plating and electroplating are performed to obtain a composite mold metal nickel plate N. Next, the micro-relief three-dimensional structure array B on the composite mold metal nickel plate N is copied to one side surface of the substrate G01 using a rotary nanoimprinting method. After curing, a micro-relief three-dimensional structure array layer G02 is formed on one side surface of the substrate G01. Finally, a reflective medium layer G03 is set on the surface of the micro-relief three-dimensional structure array layer G02 to obtain an optical anti-counterfeiting element G.

[0092] Since the micro-image described in this embodiment is not at the focal point of the lens array, the final observed image is a black, positively magnified virtual image, and the magnification of the image conforms to the magnification principle of the microlens array: When Tp Greater than T L At that time, a sunken image (background) is displayed; see [link / reference]. Figure 5 When T p Less than T L When the image floats up (foreground), see [link / reference]. Figure 9 .

[0093] Example 2:

[0094] like Figure 6 As shown, this second embodiment is basically the same as the first embodiment, except that the microlens array is a concave lens array, as described in detail below:

[0095] The image (vector or bitmap file) to be presented is decomposed into a micro-image array P. At the same time, based on the designed parameters such as the period, crown height, aperture, and array (rectangular, hexagonal, circular, random distribution) of the microlenses, a microlens array L (concave microlens array L-) is made.

[0096] Then, the micro-image array P and the microlens array L are combined using an intersection superposition method to synthesize the surface morphology and curvature of the two into a micro-relief three-dimensional microstructure N. The surface curve height of the micro-image array P is approximately 1 / 2 the height of the concave microlens array L (see...). Figure 6 6a);

[0097] Then, using the rotary nanoimprinting method, the micro-relief three-dimensional microstructure array is replicated onto the substrate 1 by curing the coating layer 2, and a reflective medium layer 3 is placed on the surface of the micro-relief three-dimensional microstructure array (non-substrate connection surface).

[0098] Finally, the image of the moiré amplifier will be observed through the substrate 1 direction (see...). Figure 6 (6b in the middle).

[0099] Specifically, such as Figure 7As shown: The designed micro-image array P and concave microlens array L- are spatially modulated in a three-dimensional structure. The surface morphology and curvature of the micro-image array P and the concave microlens array L- are synthesized using an intersection superposition method to obtain a micro-relief three-dimensional microstructure N. Then, the micro-relief three-dimensional microstructure N is recorded onto a photosensitive layer D on a photolithographic glass through exposure and development, forming a micro-relief three-dimensional structure array A on the photosensitive layer D. Chemical plating and electroplating are then performed to obtain a nickel plate F. Finally, the micro-relief three-dimensional structure array A on the nickel plate is replicated using an imprinting method. Based on the packaging design requirements, the holographic laser effect structure is combined and arranged to obtain a composite mold of micro-relief three-dimensional structure array B. Then, chemical plating and electroplating are performed to obtain a composite mold metal nickel plate N. Next, the micro-relief three-dimensional structure array B on the composite mold metal nickel plate N is copied to one side surface of the substrate G01 using a rotary nanoimprinting method. After curing, a micro-relief three-dimensional structure array layer G02 is formed on one side surface of the substrate G01. Finally, a reflective medium layer G03 is set on the surface of the micro-relief three-dimensional structure array layer G02 to obtain an optical anti-counterfeiting element G.

[0100] Since the micro-images designed in this embodiment are not at the focal point of the lens array, the final observed image is a black, positively magnified virtual image, and the magnification of the image conforms to the magnification principle of the microlens array: When T p Greater than T L The image (foreground) will then float upwards; see details below. Figure 7 When T p Less than T L A sunken image (background) is displayed at times; see details below. Figure 11 .

[0101] In fact, the optical anti-counterfeiting element described in this invention can be made by bonding paper to the surface of the reflective medium layer and heating and curing it to obtain laser paper with anti-counterfeiting elements; or by using a substrate with an adhesion enhancement layer in S4, and performing strong corona treatment on the surface of the micro-embossed three-dimensional structure array layer in S5 (which can increase the bonding force when vacuum-depositing the reflective medium layer later), and bonding paper to the surface of the reflective medium layer to obtain laser composite paper with anti-counterfeiting elements; or by using a release substrate in S4, and not performing surface treatment on the micro-embossed three-dimensional structure array layer in S5, and bonding paper to the surface of the reflective medium layer to obtain laser transfer paper with anti-counterfeiting elements.

[0102] Currently, under the plastic restriction order, film substrates have been banned for many packaging products. The industry often uses methods such as reducing the aperture of microlens array units to decrease film thickness, thereby reducing the use of plastic film, but this does not fundamentally solve the problem of plasticization in packaging materials. This invention can use a release substrate in S4, and simultaneously perform strong corona treatment on the surface of the micro-embossed three-dimensional structure array layer in S5, bonding paper to the surface of the reflective medium layer, and then peeling off the substrate to obtain a fully transferred laser transfer paper with anti-counterfeiting elements, thus achieving plasticization of packaging. Alternatively, a substrate with an adhesion-enhancing layer can be used in S4, and the surface of the micro-embossed three-dimensional structure array layer can remain untreated in S5, while paper is bonded to the surface of the reflective medium layer, and then the substrate can be peeled off the micro-embossed three-dimensional structure layer to obtain a medium laser transfer paper with a three-dimensional structure of anti-counterfeiting elements, similarly achieving the goal of plasticization of packaging.

[0103] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing an optical anti-counterfeiting element with an intersecting micro-relief three-dimensional structure, characterized in that, include: S1. Fabrication of a micro-relief three-dimensional structure array: Design a micro-image array and a microlens array, perform spatial three-dimensional architecture modulation on the micro-image array and the microlens array so that the fixed points of the micro-image array and the microlens array basically coincide, and then synthesize and superimpose them to obtain an intersecting micro-relief three-dimensional structure array, and generate a micro-relief lithography file corresponding to the intersecting micro-relief three-dimensional structure array; the synthesis and superposition specifically involves: intersecting and superimposing the surface morphology and curvature of the micro-image array and the microlens array, so that the micro-image array is nested in the microlens array; S2. Preparation of a nickel plate: Based on the micro-relief photolithography file generated in S1, the photosensitive adhesive layer on the photolithography glass is exposed and cleaned to obtain a micro-relief three-dimensional structure array A recorded on the photosensitive adhesive layer. Then, chemical plating is performed on the surface of the micro-relief three-dimensional structure array A to form a conductive silver layer. Then, it is immersed in an electrolytic tank for electroplating to obtain a nickel plate. The angle between the boundary sidewall of the intersection of the micro-image array and the microlens array in the micro-relief three-dimensional structure array A and the photosensitive adhesive layer is ≥60 degrees. S3. Preparation of composite mold nickel plate: The micro-relief three-dimensional structure array A on the nickel plate is replicated by imprinting method, and array A is combined and arranged with other holographic laser structures according to packaging design requirements to obtain a composite mold with micro-relief three-dimensional structure array B. Then, chemical plating is performed on the surface of the micro-relief three-dimensional structure array B to form a conductive silver layer, and then it is immersed in an electrolytic tank for electroplating to obtain the composite mold nickel plate. S4. Preparation of optical anti-counterfeiting film: The micro-relief three-dimensional structure array B on the composite mold metal nickel plate obtained in S3 is copied to one side surface of the substrate by imprinting method and cured to form a micro-relief three-dimensional structure array layer on one side surface of the substrate, thus obtaining an optical anti-counterfeiting film. S5. Fabrication of a reflective medium layer: A reflective medium layer is disposed on the surface of the micro-relief three-dimensional structure array layer of the optical anti-counterfeiting film obtained in S4; In S1, the linewidth of the micro-image array in the micro-relief three-dimensional structure array ranges from 500 nanometers to 50 micrometers, and the structural periods of the micro-image array and the microlens array are similar. Furthermore, the ratio of the magnification of the micro-images in the micro-image array after imaging with the optical anti-counterfeiting element to the period difference between the micro-image array and the microlens array should meet the following requirements: Magnification In the formula, TL is the lens period and Tp is the image period; Lens curvature radius r: In the formula, h is the lens height. Lens size; lens focal length In the formula, n is the refractive index; Moiré image size 2. The preparation method according to claim 1, characterized in that, In step S2, before exposure, the method further includes: adjusting the exposure energy compensation according to the photosensitive adhesive layer to improve the generation quality of the surface curvature of the micro-image array and microlens array in the micro-relief three-dimensional structure array A.

3. The preparation method according to claim 1, characterized in that, In step S2, the thickness of the photosensitive adhesive layer is 3 to 10 micrometers.

4. The preparation method according to claim 1, 2, or 3, characterized in that, The surface curve height of the microtext array is approximately half the height of the microlens array.

5. The preparation method according to claim 4, characterized in that, The exposure in S2 is either a single exposure to create the micro-image array and microlens array of the micro-relief three-dimensional structure array A, or a double exposure to create the microlens array and micro-image array of the micro-relief three-dimensional structure array A sequentially.

6. The preparation method according to claim 1, 2, 3, or 5, characterized in that, The substrate mentioned in S4 is a substrate with an adhesion enhancement layer. In S5, while a reflective medium layer is set on the surface of the micro-relief three-dimensional structure array layer of the optical anti-counterfeiting film obtained in S4, the surface of the micro-relief three-dimensional structure array layer is subjected to strong corona treatment.

7. The preparation method according to claim 1, 2, 3, or 5, characterized in that, In step S4, the substrate is a release substrate. In step S5, while a reflective medium layer is set on the surface of the micro-relief three-dimensional structure array layer of the optical anti-counterfeiting film obtained in step S4, the surface of the micro-relief three-dimensional structure array layer is subjected to strong corona treatment.

8. The preparation method according to claim 1, 2, 3, or 5, characterized in that, The substrate in S4 is a substrate with an adhesion enhancement layer, and the surface of the micro-relief three-dimensional structure array layer is not treated in S5.

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