A 3D anti-counterfeiting paper printing transfer method using microlens array

Abstract

This invention relates to a 3D anti-counterfeiting paper printing transfer method using a microlens array, belonging to the field of anti-counterfeiting in paper (cigarette) box packaging. This invention applies microlens anti-counterfeiting technology to cigarette packaging through a paper printing transfer process to obtain anti-counterfeiting patterns with strong spatial three-dimensionality and environmental friendliness. This invention transfers a high-resolution microlens array to the surface of the packaging paper, overcoming the pollution problems caused by the non-degradability of PET; furthermore, by replacing the existing laser holographic information layer with a film layer engraved with the microlens array, this invention can deflect incident light, acting as an optical lens to image the base pattern, achieving a floating or sinking three-dimensional effect, resulting in a more three-dimensional image.

Description

Technical Field

[0001] This invention belongs to the field of anti-counterfeiting in paper (cigarette) box packaging, specifically involving a 3D anti-counterfeiting paper printing transfer method using a microlens array. Background Technology

[0002] The high profits of tobacco products have led some unscrupulous individuals to manufacture and sell counterfeit cigarettes, causing enormous losses to the country, businesses, and consumers. Currently, the main anti-counterfeiting technologies used in cigarette packaging include material anti-counterfeiting, printing anti-counterfeiting, digital anti-counterfeiting, and optical anti-counterfeiting, primarily laser holography. Due to environmental protection requirements, PET-based plastic films are not used in paper (cigarette) box packaging.

[0003] Microlens security films typically use PET / PC / PMMA as a substrate, with lens layers and graphic layers processed on both sides of the substrate. The micro-pattern array is imaged by the microlens array, forming a magnified and floating (or sunken) pattern array on the relative graphic surface. In practical applications, microlens security films need to be laminated onto product packaging, creating a spatially layered, three-dimensional effect with the packaging surface pattern. Microlens security films are widely used in banknote security strips (US dollars), decorative 3D paintings, and anti-counterfeiting labels for high-end products. However, in the environmentally conscious cigarette packaging sector, PET-based plastic microlens security films cannot be directly applied through lamination because the PET material used is non-degradable.

[0004] The principle of 3D display using microlens arrays is as follows: Figure 7 As shown, this optical system consists of a three-layer structure: from bottom to top, a micropattern array, a microlens array, and an imaging pattern. The micropatterns are arranged at a certain period (an array of letters "f") and placed at the focal point of the microlens. These two layers form a micro-focusing system, achieving a two-dimensional moiré imaging effect, i.e., a magnified micropattern (a magnified letter "f"). By adjusting the period and relative angle of the microlens array and the micropattern array, different magnifications, and whether the pattern is floating or sinking, can be achieved.

[0005] Microlens 3D anti-counterfeiting films typically consist of a microlens layer, a transparent layer, and an image layer. The microlens layer and the image layer are composed of microlens arrays and image arrays arranged in a certain periodic array, respectively. When the two are superimposed, they produce magnified moiré fringes.

[0006] like Figure 8 As shown, patent application 201910293990.5 discloses a microlens anti-counterfeiting film, which consists of, from top to bottom, a lens layer, a substrate layer, and a graphic information layer. The lens layer, substrate layer, and graphic information layer are bonded together using a soft film process.

[0007] like Figure 9As shown, patent application 202022062188.6 discloses a structural color anti-counterfeiting film based on a microlens array. Using PET as a substrate, photoresist is coated on both sides of the PET, and a lens layer and an image layer are obtained through UV imprinting. This patent application uses PET as a substrate and processes lens and image layers on both sides of the PET. However, PET material is non-degradable and cannot be directly applied to cigarette packaging, which has high environmental protection requirements.

[0008] like Figure 10 , 11 As shown, patent application 201420299179.0 discloses a 3D stereoscopic dynamic and graphic micro-anti-counterfeiting transfer film. The structure includes six layers, which, from bottom to top, are a PET film, a chemical coating, a micro-anti-counterfeiting information layer, a UV photosensitive adhesive layer, a three-dimensional dynamic information layer, and an aluminum-plated layer. This patent application also applies 3D stereoscopic dynamic patterns to cigarette box packaging through paper transfer. However, the 3D stereoscopic dynamic pattern generated in this patent application is a 1-2μm thick laser grating layer. The principle of grating imaging is that the grating interacts with the background image to form interference fringes, which cannot form a floating or sinking three-dimensional effect. Summary of the Invention

[0009] The purpose of this invention is to provide a 3D anti-counterfeiting paper printing transfer method using microlens arrays. Through the paper printing transfer process, microlens anti-counterfeiting technology is applied to cigarette packaging to obtain anti-counterfeiting patterns with strong three-dimensional effect and environmental protection.

[0010] To achieve the above objectives, the technical solution of the present invention is: a 3D anti-counterfeiting paper printing transfer method using microlens arrays, which applies microlens anti-counterfeiting technology to cigarette packaging through paper printing transfer process to form 3D anti-counterfeiting paper with microlens array, thereby obtaining an anti-counterfeiting pattern with strong spatial three-dimensionality and environmental protection.

[0011] In one embodiment of the present invention, the microlens array 3D anti-counterfeiting paper uses cigarette packaging paper as a substrate, and from bottom to top consists of cigarette packaging paper, an image layer, an adhesive layer, a lens layer, and a release protective layer; the image layer is imprinted on the surface of the cigarette packaging paper by means including printing, transfer, or embossing; the lens layer and the image layer are bonded together by the adhesive layer; the lens layer consists of an optical refractive area and a transparent area; the release protective layer can effectively protect the lens surface and also serves to peel it off from the PET film.

[0012] In one embodiment of the present invention, the optical refraction region is an arc-shaped region with a lens shape, and light is refracted when it passes through the arc-shaped region.

[0013] In one embodiment of the present invention, the preparation steps of the microlens array 3D anti-counterfeiting paper include: a microlens layer preparation step, a micro-image layer preparation step, and an adhesive bonding step.

[0014] In one embodiment of the present invention, the microlens layer includes a PET substrate, a release protective layer, a lens layer, and an adhesive layer. The specific steps for preparing the microlens layer are as follows:

[0015] (1) Coating: PET film is selected as the substrate, and a release protective layer is coated on the PET film. The height of the release protective layer is greater than the sagitta H of the microlens unit in the lens layer, and H satisfies...

[0016]

[0017] Where r is the radius of curvature of the microlens unit in the lens layer, and D is the aperture of the microlens unit in the lens layer;

[0018] (2) Microlens surface embossing: Imprinting is performed on a PET film coated with a release protective layer using a film roller press;

[0019] (3) Lens layer filling: The release protective layer is rolled to form a concave lens shape, and the concave area is filled by applying adhesive; at the same time, the adhesive layer thickness is increased to obtain a transparent layer to meet the predetermined imaging distance; the lens layer thickness is H+F, where F satisfies

[0020]

[0021] Where n1 is the refractive index of the release liner and n2 is the refractive index of the lens layer;

[0022] (4) Applying adhesive: After the lens layer is filled, a layer of water-based transfer adhesive is applied to the surface of the lens layer on the laminating machine to form an adhesive layer.

[0023] In one embodiment of the present invention, the main component of the release protective layer is a highly transparent oil-based or water-based polymeric resin with a refractive index of 1.4-1.6.

[0024] In one embodiment of the present invention, the rolling die used in the thin film rolling mill is a nickel working die with a microlens array engraved on it; the nickel working die processing process is as follows: the microlens array metal master die is processed by ultra-precision milling or photolithography; the microlens array metal master die is chemically electroformed to obtain the nickel working die; the nickel working die is laser spliced ​​to obtain the roller nickel working die.

[0025] In one embodiment of the present invention, the lens layer is made of polyurethane adhesive with high transparency and a refractive index of 1.5-1.7.

[0026] In one embodiment of the present invention, the micro-image layer preparation steps are as follows:

[0027] Using cigarette packaging paper as a substrate, micro-patterns are printed using a thin-film gravure printing machine to form a micro-image layer. The period of the micro-pattern array matches the period of the microlens array in the microlens layer. When the period of the micro-pattern array is greater than the period of the microlens array, the resulting moiré magnified pattern is a floating real image; when the period of the micro-pattern array is less than the period of the microlens array, the resulting moiré magnified pattern is a sinking virtual image.

[0028] In one embodiment of the present invention, the bonding step is specifically as follows:

[0029] (1) Alignment and lamination: The microlens layer coated with transfer adhesive and the cigarette packaging paper with micro-text and image layer are aligned according to a predetermined cycle, laminated by a laminating machine, and then rolled up after drying and cooling.

[0030] (2) Peeling: After the composite is completed, it is cured at room temperature and the PET film substrate of the microlens layer is separated from the release protective layer by a peeling machine. The separated PET film can be recycled.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The method of the present invention transfers a high-resolution microlens array to the surface of packaging paper, overcoming the pollution problem caused by the non-degradability of PET.

[0033] 2. The method of the present invention replaces the existing laser holographic information layer with a film layer engraved with a microlens array, which can deflect the incident light and act as an optical lens to image the bottom pattern, thereby achieving a three-dimensional effect of floating or sinking, and the imaged pattern is more three-dimensional. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the optical structure of a microlens array 3D anti-counterfeiting paper, an example of the present invention.

[0035] Figure 2 This is a schematic diagram of a microlens layer structure according to an example of the present invention.

[0036] Figure 3 This is a schematic diagram of the microlens array arrangement in an example of the present invention.

[0037] Figure 4 This is a schematic diagram of a microlens surface embossing method according to an example of the present invention.

[0038] Figure 5 This is a schematic diagram of a micro-pattern array arrangement according to an example of the present invention.

[0039] Figure 6 This is a schematic diagram of an alignment and compounding method according to an example of the present invention.

[0040] Figure 7The principle of 3D display using microlens arrays

[0041] Figure 8 The illustration is for prior art 1.

[0042] Figure 9 The illustration is for prior art 2.

[0043] Figure 10 Figure 1 shows the existing technology.

[0044] Figure 11 Figure 2 shows the prior art. Detailed Implementation

[0045] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0046] This invention provides a 3D anti-counterfeiting paper printing transfer method using a microlens array. Through a paper printing transfer process, microlens anti-counterfeiting technology is applied to cigarette packaging to form a 3D anti-counterfeiting paper with a microlens array, resulting in a strong three-dimensional and environmentally friendly anti-counterfeiting pattern. The 3D anti-counterfeiting paper with a microlens array uses cigarette packaging paper as a substrate. From bottom to top, it consists of cigarette packaging paper, an image layer, an adhesive layer, a lens layer, and a release protective layer. The image layer is imprinted on the surface of the cigarette packaging paper using methods including printing, transfer, or embossing. The lens layer is bonded to the image layer with the adhesive layer. The lens layer consists of an optical refractive area and a transparent area. The release protective layer effectively protects the lens surface of the lens layer and also serves to peel it off from the PET film.

[0047] The following is a specific preferred embodiment of the present invention.

[0048] A schematic diagram of the optical structure of the microlens array 3D anti-counterfeiting paper is shown below. Figure 1 As shown: Using cigarette packaging paper as a substrate, from bottom to top, the layers are paper, graphic layer, adhesive layer, lens layer, and protective layer. The graphic layer can be printed onto the paper surface by printing, transfer, or embossing; the lens layer is bonded to the graphic layer by the adhesive layer; the lens layer consists of an optical refractive area (an arc-shaped area with a lens shape through which light is refracted) and a transparent area (where light is not refracted); the release protective layer effectively protects the lens surface and also helps to peel it off from the PET film.

[0049] The main steps in forming 3D anti-counterfeiting paper with microlens array are microlens layer preparation, micro-image layer preparation, and bonding.

[0050] 1. Fabrication of microlens layer

[0051] The microlens layer comprises a PET substrate, a release layer, a lens layer, and an adhesive layer, such as... Figure 2 As shown.

[0052] (1) Select a 400-line microlens array, arranged in a tangential manner, such as... Figure 3 As shown, the aperture of the unit lens is D = 63.5 μm, the center-to-center distance of the lens units is Δ1 = 63.5 μm, and the radius of curvature is r = 35 μm. The release layer uses PET coated with special silicone adhesive with a refractive index of 1.41; the lens layer uses water-based polyurethane adhesive with a refractive index of 1.56. Calculations show H = 20.3 μm and F = 233.3 μm.

[0053] (2) Coating: PET film is selected as the substrate, and a release layer is coated on the PET film. Its main component is oil-based or water-based polymeric resin with a refractive index of 1.41. Due to the unevenness of the coating height, in order to ensure the integrity of the microlens array during the imprinting process, the height of the release layer needs to be greater than the sagittal height H of the microlens unit, generally leaving a margin of 3-6 μm. In this invention, the height of the release layer is controlled at 23.3-26.3 μm.

[0054] (3) Microlens surface embossing: Imprinting is performed on a PET film coated with a release layer using a film roller press. After embossing, a concave spherical array is formed on the surface of the release layer, such as... Figure 4 As shown.

[0055] (4) Lens layer filling: The release layer is rolled into a concave lens shape, and the concave surface of the release layer is filled by applying adhesive, while simultaneously increasing the adhesive layer thickness to meet a certain imaging distance. The lens layer uses a highly transparent water-based polyurethane adhesive with a refractive index of 1.56, and its thickness is H+F, where F should meet the following requirements.

[0056]

[0057] Where n1 is the refractive index of the release layer and n2 is the refractive index of the lens layer.

[0058] (5) Applying adhesive: After the lens layer is filled, a layer of water-based transfer adhesive is applied to the surface to form an adhesive layer. The main components of the water-based transfer adhesive are water-based polymeric acrylic acid or styrene-butadiene emulsion. The microlens layer and the microtext layer are bonded together through the adhesive layer.

[0059] 2. Preparation of microtext layers

[0060] Using cigarette packaging paper as a substrate, micro-patterns are printed using a thin-film gravure printing machine. The micro-pattern array is arranged as follows: Figure 5 As shown, the unit size d is less than 50% of the microlens unit size D. In this invention, d = 31.75 μm. The micropattern unit spacing Δ2 is determined by the microlens array period Δ1 and the magnification M, i.e.

[0061]

[0062] Taking a magnification of 40 as an example, Δ2 = 61.9um.

[0063] 3. Gluing

[0064] (1) Alignment and lamination: The microlens transfer film coated with transfer adhesive is aligned with the paper printed with micro-patterns at a certain interval. The centers of the first row and first column units of the microlens array and the micro-pattern array are aligned, with the central axes of the first row and first column units coinciding. Figure 6 As shown.

[0065] (2) After lamination, the PET film is cured at room temperature for 3 hours. The release layer is then peeled off using a peeling machine. The separated PET film can be recycled for the coating process in step (1). This reduces costs and overcomes the pollution problem caused by the non-degradability of PET.

[0066] The above are preferred embodiments of the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A 3D anti-counterfeiting paper printing transfer method using a microlens array, characterized in that, By using a paper printing transfer process, microlens anti-counterfeiting technology is applied to cigarette packaging to form a microlens array 3D anti-counterfeiting paper, thereby obtaining an anti-counterfeiting pattern with a strong three-dimensional effect and environmental protection. The fabrication steps of the microlens array 3D anti-counterfeiting paper include: a microlens layer fabrication step, a micro-image layer fabrication step, and an adhesive bonding step; the microlens layer includes a PET substrate, a release protective layer, a lens layer, and an adhesive layer, and the specific fabrication steps of the microlens layer are as follows: (1) Coating: PET film is selected as the substrate, and a release protective layer is coated on the PET film. The height of the release protective layer is greater than the sagitta H of the microlens unit in the lens layer, and H satisfies... Where r is the radius of curvature of the microlens unit in the lens layer, and D is the aperture of the microlens unit in the lens layer; (2) Microlens surface embossing: Imprinting is performed on a PET film coated with a release protective layer using a film roller press; (3) Lens layer filling: The release protective layer is rolled to form a concave lens shape, and the concave area is filled by applying adhesive; at the same time, the adhesive layer thickness is increased to obtain a transparent layer to meet the predetermined imaging distance; the lens layer thickness is H+F, where F satisfies Where n1 is the refractive index of the release liner and n2 is the refractive index of the lens layer; (4) Applying adhesive: After the lens layer is filled, a layer of water-based transfer adhesive is applied to the surface of the lens layer on the laminating machine to form an adhesive layer.

2. The 3D anti-counterfeiting paper printing transfer method using a microlens array according to claim 1, characterized in that, The microlens array 3D anti-counterfeiting paper uses cigarette packaging paper as a substrate. From bottom to top, it consists of cigarette packaging paper, graphic layer, adhesive layer, lens layer, and release protective layer. The graphic layer is printed on the surface of the cigarette packaging paper. The lens layer and graphic layer are bonded together with the adhesive layer. The lens layer consists of an optical refractive area and a transparent area; the release protective layer can effectively protect the lens surface of the lens layer and also serves to peel it off from the PET film.

3. The 3D anti-counterfeiting paper printing transfer method using a microlens array according to claim 2, characterized in that, The printing method is either transfer printing or embossing.

4. The 3D anti-counterfeiting paper printing transfer method using a microlens array according to claim 2, characterized in that, The optical refraction region is an arc-shaped area with a lens shape, through which light is refracted.

5. The 3D anti-counterfeiting paper printing transfer method using a microlens array according to claim 1, characterized in that, The release protective layer is mainly composed of highly transparent oil-based or water-based polymeric resin with a refractive index of 1.4-1.

6.

6. The 3D anti-counterfeiting paper printing transfer method using a microlens array according to claim 1, characterized in that, The rolling die used in the film rolling mill is a nickel working die with a microlens array engraved on it. The nickel working die is processed by: processing the microlens array metal master die by ultra-precision milling or photolithography; obtaining the nickel working die by chemical electroforming from the microlens array metal master die; and obtaining the roller nickel working die by laser splicing from the nickel working die.

7. A 3D anti-counterfeiting paper printing transfer method using a microlens array according to claim 1, characterized in that, The lens layer is made of polyurethane adhesive with a refractive index of 1.5-1.

7.

8. A 3D anti-counterfeiting paper printing transfer method using a microlens array according to claim 1, characterized in that, The specific steps for preparing the micro-image layer are as follows: Using cigarette packaging paper as a substrate, micro-patterns are printed using a thin-film gravure printing machine to form a micro-image layer. The period of the micro-pattern array matches the period of the microlens array in the microlens layer. When the period of the micro-pattern array is greater than the period of the microlens array, the resulting moiré magnified pattern is a floating real image; when the period of the micro-pattern array is less than the period of the microlens array, the resulting moiré magnified pattern is a sinking virtual image.

9. A 3D anti-counterfeiting paper printing transfer method using a microlens array according to claim 1, characterized in that, The specific bonding steps are as follows: (1) Alignment and lamination: The microlens layer coated with transfer adhesive and the cigarette packaging paper with micro-text and image layer are aligned according to a predetermined cycle, laminated by a laminating machine, and then rolled up after drying and cooling. (2) Peeling: After the composite is completed, it is cured at room temperature and the PET film substrate of the microlens layer is separated from the release protective layer by a peeling machine. The separated PET film can be recycled.

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