Manufacturing method of optical anti-counterfeiting film and product thereof

Abstract

The invention provides an optical anti-counterfeiting film with a three-dimensional dynamic display effect, the minimum function structure of the optical anti-counterfeiting film comprises a first Moire image layer, a transparent optical refraction layer and a second Moire image layer which generates a Moire effect with the first Moire image layer, one of two coherent Moire images is processed on the front surface of the transparent optical film, and the other of the two coherent Moire images is processed on the rear surface of the transparent optical refraction layer. And the other one of the two coherent Moire images is processed at the corresponding position of the rear surface, and the period of the Moire image has a strict mathematical relationship with the refractive index n of the optical transparent material and the thickness h of the optical transparent material, so that a three-dimensional dynamic pattern effect capable of being observed by naked eyes is realized. According to different processing methods, the manufacturing method of the optical anti-counterfeiting film and the product of the optical anti-counterfeiting film can be realized from the cost of common printing to the cost of high-precision micro-nano processing such as electron beam lithography, the market requirements of various grades can be met, and the anti-counterfeiting difficulty grade can be changed according to different image design and processing methods.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an optical anti-counterfeiting film, a method for manufacturing an optical anti-counterfeiting film and its product. Background Art

[0002] In the prior art, the realization of a three-dimensional dynamic pattern mainly relies on grating materials. A pattern designed accordingly is processed on one side of the grating material to achieve a three-dimensional dynamic effect. Traditional three-dimensional printing mainly uses columnar lens grating materials with a line count below 100 LPI, which have the disadvantages of relatively thick material thickness, insufficient material processing accuracy, being easy to imitate, incomplete pattern transformation, jumping, etc. With the progress of micro-nano processing technology, columnar lens grating materials with a line count above 300 LPI have emerged, but they have the disadvantage of relatively high manufacturing cost, and only a few high-end brand products can bear the usage cost. Similarly, a three-dimensional dynamic anti-counterfeiting film based on the micro-lens Moiré imaging technology is also realized through micro-nano processing technology, and has the disadvantages of long processing cycle and extremely high cost for small batches.

[0003] With the increasing number of fake products day by day, it is extremely important to effectively distinguish and protect high-quality goods. Consumers' requirements for the interestingness, interactivity and safety of product appearance are increasing day by day. There is an urgent need for a method for preparing a packaging material with an anti-counterfeiting function that is easy to distinguish, interesting, low-cost and highly safe. Summary of the Invention

[0004] In the present invention, two coherent Moiré images are respectively processed on both sides of a transparent optical material in alignment. When viewed from one side through the transparent optical material, at different viewing angles, the Moiré image on the other side generates minute displacements in the left-right, front-back, and up-down directions through the refraction of the transparent material, thereby forming a dynamic effect and generating an up-down displacement in the thickness direction, so that a three-dimensional effect can be observed. It is a method for preparing a packaging material with an anti-counterfeiting function that is easy to distinguish, highly interesting, low-cost and highly safe.

[0005] An optical anti-counterfeiting film with a three-dimensional dynamic display effect provided by the present invention is a transparent optical film with front and back surfaces. One of two coherent Moiré images is processed on the front surface of the transparent optical film, and the other is processed at the corresponding position on the back surface. Moreover, there is a strict mathematical relationship between the period of the Moiré image, the refractive index n of the optical transparent material, and the thickness h of the optical transparent material, realizing a three-dimensional dynamic pattern effect that can be observed with the naked eye from both the front and back surfaces.

[0006] A method for manufacturing an optical anti-counterfeiting film provided by the present invention is characterized in that: The processing method of the moiré image in the transparent optical material includes common processing methods for tiny lines or patterns such as publishing and printing, post-coloring after micro-nano imprinting, imprinting the moiré image by diffraction grating, and laser direct writing. New optical characteristics are formed according to various processing methods. For example, after imprinting the moiré image by diffraction grating, it has a color effect, and after sub-wavelength grating, it has a viewing angle color-changing effect close to a single color. Another example is that when using the printing process, different single colors are printed on each part, and a color-changing effect with a viewing angle change will also appear after alignment and color collision.

[0007] When designing the moiré image, the relationship between the maximum value m of the stripe period in the horizontal and vertical directions of the stripe moiré image, the refractive index n of the optical transparent material, and the thickness h of the optical transparent material is as follows: m ≤ 2h * tan(arcsin(1 / n)). To ensure a better three-dimensional dynamic effect, the preferred maximum value of the stripe period m ≤ 2h * tan(arcsin(sin60° / n)).

[0008] When designing the moiré image with a tiny graphic array, the relationship between the horizontal width of the unit image of the tiny array graphic and the width d in the vertical direction, the refractive index n of the optical transparent material, and the thickness h of the optical transparent material is as follows: d ≤ 2h * tan(arcsin(1 / n)), the difference Δ between the repetition periods of the two-layer coherent tiny graphic arrays ≤ 2h * tan(arcsin(1 / n)), and the periods m in the horizontal and vertical directions of each layer of tiny array graphics ≤ 6h * tan(arcsin(1 / n)).

[0009] The transparent optical material is selected from one or more materials such as polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polystyrene (PS), and thermoplastic polyurethane rubber (TPU). According to factors such as the image processing method, cost, reliability, and usage environment requirements, a suitable transparent optical material is selected.

[0010] According to the above, the minimum functional structure of the optical anti-counterfeiting film of the present invention is the first moiré image layer, the transparent optical refraction layer, and the second moiré image layer that generates the moiré effect with the first moiré image layer. Any disassembly and combination structure with the above minimum functional structure and having the above characteristics should be regarded as the protection scope of the present invention. For example, printing the first moiré image layer on one side of the transparent optical material, and then printing the second moiré image layer that generates the moiré effect with the first moiré image layer on the packaging paper. By compounding the two materials, the minimum optical functional structure is obtained to form a three-dimensional dynamic display effect. Although it seems not to violate the claims of the present invention on the surface, in fact, it follows the principle and mathematical relationship characteristics of the present invention and should be regarded as the protection scope of the present invention.

[0011] A manufacturing method of an optical anti-counterfeiting film and its product, characterized in that on the basis of the optical anti-counterfeiting film, functional layers such as a protective layer, an information layer, a reflective layer, an adhesive layer, and an isolation layer are added on one or both sides to change the observability of the three-dimensional dynamic effect, the local or global visual metallic texture, the light intensity contrast, etc., and form a suitable material for manufacturing cards, labels, decorative films, and packaging products.

[0012] For the manufacturing method of the optical anti-counterfeiting film and its product of the present invention, according to different processing methods, the cost can be realized from the cost of ordinary printing to the cost of high-precision micro-nano processing such as electron beam lithography, covering market demands of various grades, and the anti-counterfeiting difficulty level can also be changed according to different image designs and processing methods. Brief Description of the Drawings

[0014] Figure 1 is an image to be moiré designed.

[0015] Figure 2 is the first moiré image layer after moiré design of Figure 1.

[0016] Figure 3 is the second moiré image layer after moiré design of Figure 1.

[0017] Figure 4 is the visual effect diagram of the optical anti-counterfeiting film prepared from 0.1mm thick PET material processed according to Figure 2 and Figure 3 at various viewing angles.

[0018] Figure 5 is the first moiré image layer of an array moiré image design.

[0019] Figure 6 is the second moiré image layer of an array moiré image design.

[0020] Figure 7 is the first moiré image layer of a hybrid design of stripe moiré and array moiré.

[0021] Figure 8 is the second moiré image layer of a hybrid design of stripe moiré and array moiré.

[0022] Figure 9 is the visual effect diagram of the optical anti-counterfeiting film prepared from 0.1mm thick PET material processed according to Figure 7 and Figure 8 at a 0-degree viewing angle. Detailed Description of the Invention

[0023] The present invention will be further described below by way of examples, but the present invention is not limited to the scope of the described examples. According to the foregoing, the present invention focuses on a low-cost image processing solution. Therefore, in the examples, only the printing processing method is taken as an example.

[0024] Before the specific implementation, let's briefly introduce the basic knowledge of human eye vision. According to existing medical knowledge, the visual acuity of the human eye refers to the degree of the visible angle of the human naked eye. For humans, it is usually 124 degrees, and when concentrating, it is about one-fifth, that is, 25 degrees. The overlapping visual field of the two eyes is 124 degrees. That is to say, within the range visible to the human eye, only the objects within this 124-degree viewing angle have a three-dimensional sense. The comfortable viewing field of a single eye is 60 degrees, which means that the objects viewed and the photos taken are best at 60 degrees. Generally speaking, for the image projected onto the human eye retina, only the central part can be clearly distinguished, which is called the resolution viewing field, about 15 degrees. The range from 15 degrees to 30 degrees is called the effective viewing field, and the human eye can immediately see the existence and movement trajectory of the object. Embodiment

[0025] In this embodiment, based on a 0.1-mm-thick PET material, the design of the moiré fringe image and how to make it into an optical anti-counterfeiting film are described in detail. According to the refractive index of 1.6 of the PET material and a thickness of 0.1 mm, it can be calculated that the maximum value of the moiré fringe period is approximately 0.16 mm, and the value at the maximum optimal viewing angle of the human eye is approximately 0.125 mm. Taking the moiré fringe image period of 0.12 mm as an example, according to Figure 1 The number of images changing sequentially from the inside to the outside as shown is 6. Calculating, the width of a single fringe is 0.02 mm. After Figure 1 successively displacing all the images by 0.02 for striping, we get Figure 2 , Figure 2 which is the first moiré image layer. After striping Figure 1 as a whole, we get Figure 3 , Figure 3 which is the second moiré image layer. Printing Figure 2 and Figure 3 on the corresponding positions of both sides of a 0.1-mm-thick PET film material respectively at a resolution of 2540 DPI (the characteristic line width is 0.01 mm), an optical anti-counterfeiting film with a three-dimensional dynamic display effect can be obtained. According to the refractive index formula and trigonometric relationship, within a 120-degree viewing angle range, for the imaging of the second moiré image layer relative to the first moiré image layer, there is a displacement of 2h*tan(arcsin(sin60° / n)) (substituting h = 0.1 mm, n = 1.6), that is, approximately 0.125 mm. When observing the optical film from the front and shaking the printed pattern left and right, at each viewing angle, due to the different positions of the imaging of the second moiré image layer relative to the first moiré image layer, visual patterns with different effects are presented. Under continuous change, a three-dimensional dynamic display effect is presented, Figure 4 as shown. Due to the limitation of the human eye's ability to distinguish tiny objects, normally only the dynamic three-dimensional effect formed by the sequential light and dark changes of the 6 graphics designed in this anti-counterfeiting film can be clearly perceived. Embodiment

[0026] In this embodiment, based on a PET material with a thickness of 0.1 mm, the design of the array Moiré image and how to fabricate it into an optical anti-counterfeiting film are described in detail. According to the refractive index of 1.6 and the thickness of 0.1 mm of the PET material, it can be calculated that the maximum value of the displacement period of the Moiré array pattern is approximately 0.16 mm, and the value at the maximum and best viewing angle of the human eye is approximately 0.125 mm. Taking the minimum pattern of the array Moiré image of 0.1 mm as an example, the period in the X-axis (i.e., the horizontal direction) is taken as 0.18 MM, and the period in the Y-axis (i.e., the vertical direction) is taken as 0.28 MM to form array A. And the array A is copied with a half-period shift in both the X-axis and Y-axis and combined with the original A array to form a new array Moiré image, as Figure 5 shown, Figure 5 Combined with Figure 2 it is the first Moiré image layer of the hybrid design of stripe Moiré and array Moiré, as Figure 7 shown. Taking the minimum pattern of the array Moiré image of 0.1 mm, the period in the X-axis (i.e., the horizontal direction) is taken as 0.2 MM, and the period in the Y-axis (i.e., the vertical direction) is taken as 0.3 MM to form array B. And the array B is copied with a half-period shift in both the X-axis and Y-axis and combined with the original B array to form a new array Moiré image, as Figure 6 shown, Figure 6 Combined with Figure 3 it is the second Moiré image layer of the hybrid design of stripe Moiré and array Moiré, as Figure 8 shown. At a resolution of 2540 DPI (the characteristic line width is 0.01 mm), Figure 2 and Figure 3 are printed on the corresponding positions on both sides of a 0.1 mm thick PET film material respectively, and an optical anti-counterfeiting film with a three-dimensional dynamic display effect can be obtained. Figure 9 Shown as, according to Figure 7 and Figure 8Visual effect diagram of the optical anti-counterfeiting film made of 0.1 mm thick PET material prepared by processing. Due to the limitation of the human eye's ability to distinguish tiny objects, for the overlapping part of the array Moiré image, only the obvious black-and-white alternating area distribution can be perceived, and its position is different at different viewing angles. When the viewing angle changes continuously, the array Moiré pattern shows a moving effect of the black-and-white alternating area. By deeply analyzing the relative displacement of the imaging of the first Moiré image layer and the second Moiré image layer of the optical film at each angle, it can be known that when observing the optical film from the front and shaking the printed and processed pattern left and right, when the viewing angle changes continuously, the striped Moiré pattern shows a three-dimensional dynamic display effect, while the array Moiré pattern only shows a dynamic display effect that can be perceived by the human eye; when shaking the printed and processed pattern up and down, when the viewing angle changes continuously, only the array Moiré pattern shows a dynamic display effect. By deeply analyzing the above embodiments, it can be known that when the stripes of the striped Moiré image are completely consistent with the horizontal or vertical direction, only when moving orthogonally to the horizontal or vertical direction can a perceivable displacement be generated, and a three-dimensional dynamic display effect can be observed. When maintaining an inclination angle with the horizontal or vertical direction, a perceivable displacement is generated during horizontal or vertical movement, that is, there is a component with a non-zero X-axis or Y-axis, and a three-dimensional dynamic display effect can be observed from multiple angles. The array Moiré image can observe a three-dimensional dynamic display effect at 360 degrees. The speed of image change of the striped Moiré image and the array Moiré image is strongly related to the value of the relevant period parameter. The smaller the period value, the faster the change, and the higher the requirement for processing resolution. The macroscopic visual display of the Moiré image depends on the duty cycle of the stripes within a single period for display. Since the human eye has a limit in recognizing the size of an object, it is therefore preferred to design according to the specific image and processing conditions under the optimal period value. Embodiment

[0027] Taking the application of the minimum structural function of the optical anti-counterfeiting film of the present invention on packaging as an example in this embodiment, a paper box packaging containing the structural function of the optical anti-counterfeiting film of the present invention is made. First, select the thickness of the transparent optical material base film, and design the first Moiré image layer and the second Moiré image layer that generates the Moiré effect with the first Moiré image layer; print the first Moiré image layer at a suitable position on the paper, and laminate the transparent optical material base film with the paper printed with the first Moiré image layer. Then, print the second Moiré image layer that generates the Moiré effect with the first Moiré image layer on the transparent optical material base film at the corresponding position of the composite material. The normal design patterns at other positions are carried out according to the normal production process of the packaging paper box or label, and a packaging product containing the structural function of the optical anti-counterfeiting film of the present invention is obtained, forming a packaging product with an anti-counterfeiting function that is easy to distinguish, has strong interest, and has low cost and high security.

[0028] The specific embodiments of the present invention have been described above. However, those skilled in the art should understand that this is only an example, and the protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these embodiments, but such changes and modifications all fall within the protection scope of the present invention.

Claims

1. A method for making an optical anti-counterfeiting film, characterized in that: Two coherent moiré images are designed and aligned and processed on both sides of a transparent optical material to realize an optical anti-counterfeiting film with a three-dimensional dynamic pattern effect, that is, the minimum functional structure is a first moiré image layer, a transparent optical refractive layer, and a second moiré image layer that produces a moiré effect with the first moiré image layer.

2. The method for making an optical anti-counterfeiting film according to claim 1, characterized in that: The processing method of the moiré image on transparent optical materials includes common processing methods for small lines or graphics such as publishing printing, coloring after micro-nano imprinting, imprinting the moiré image by diffraction grating, and laser direct writing, and new optical characteristics are formed according to various processing methods. For example, after the moiré image is imprinted by diffraction grating, it has a color effect, and sub-wavelength grating has a viewing angle color change effect close to a single color; for example, by using a printing process, different single colors are printed on each part, and after the color is matched, a color change effect of viewing angle change will also appear.

3. The method for making an optical anti-counterfeiting film according to claim 1, characterized in that: The relationship between the maximum value m of the horizontal and vertical fringe period of the fringe moiré image and the refractive index n and thickness h of the optically transparent material is as follows: m≤2h*tan(arcsin(1 / n)). To ensure a better three-dimensional dynamic effect, the maximum value of the fringe period is preferably m≤2h*tan(arcsin(sin60° / n).

4. The method for making an optical anti-counterfeiting film according to claim 1, characterized in that: When the moiré image is designed using a micro-image array, the relationship between the horizontal width and vertical width d of the unit image of the micro-array image and the refractive index n of the optically transparent material and the thickness h of the optically transparent material is as follows: d≤2h*tan(arcsin(1 / n)), the difference in repetition period of two layers of coherent micro-image arrays Δ≤2h*tan(arcsin(1 / n)), and the period m of each layer of micro-array image in the horizontal and vertical directions ≤6h*tan(arcsin(1 / n)).

5. The method for making an optical anti-counterfeiting film according to claim 1, characterized in that: The transparent optical material is selected from one or more materials of polyethylene terephthalate (PET), polycarbonate (PC) or polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polystyrene (PS), thermoplastic polyurethane rubber (TPU), and the appropriate transparent optical material is selected according to factors such as image processing method, cost, and use environment requirements.

6. A method for manufacturing an optical anti-counterfeiting film and a product thereof, characterized in that: On the basis of the optical anti-counterfeiting film described in claim 1, functional layers such as a protective layer, an information layer, a reflective layer, a coating layer, and an isolation layer are added on one or both sides to change the observability of the three-dimensional dynamic effect, the local or global visual metallic texture, the light intensity contrast, etc., so as to make cards, labels, decorative films, packaging products, etc.

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