Functional film with 3D visual effect and preparation method thereof

Abstract

The present application relates to the technical field of optical anti-counterfeiting, and particularly relates to a functional film with 3D visual effect and a preparation method thereof. The functional film comprises a substrate layer; a first microstructure array layer composed of a plurality of first microstructure units, and the plurality of first microstructure units are periodically arranged in a direction parallel to the substrate layer, and the distance between two adjacent first microstructure units is P; a spacer layer; a second microstructure array layer composed of a plurality of second microstructure units, and the distance between two adjacent second microstructure units is P; the second microstructure unit has a preset offset (Delta x, Delta y) relative to the first microstructure unit in a plane parallel to the substrate layer; wherein, Delta x = m x P / N, Delta y = n x P / N, m and n are integers, N is an integer greater than or equal to 2, and Delta x and Delta y are not zero at the same time. The functional film prepared by the present application has dynamic 3D visual effect and excellent anti-counterfeiting performance.

Description

Technical Field

[0001] This invention relates to the technical field of optical anti-counterfeiting, specifically to a functional film with 3D visual effects and its preparation method. Background Technology

[0002] With the development of the market economy, product anti-counterfeiting has become an important means of protecting brand value and consumer rights. Currently, anti-counterfeiting technologies on the market mainly include laser holographic labels, fluorescent inks, and QR codes. Among them, anti-counterfeiting technologies based on micro-optical structures have attracted much attention due to their unique visual effects and high difficulty in counterfeiting.

[0003] In the existing technology, there are many solutions for achieving three-dimensional anti-counterfeiting using microlens array technology. For example, patent document with application number CN202511309978.0 discloses a multilayer body with 3D anti-counterfeiting effect, its preparation method, and anti-counterfeiting packaging material. The multilayer body includes a substrate layer with raised and flat surfaces, a microlens array layer disposed on the convex surface, and a micro-graphic layer disposed on the concave surface.

[0004] However, most of the optical anti-counterfeiting technologies mentioned above use a classic moiré magnification structure that combines a single-layer microlens with a single-layer micro-image. Their imaging principle is relatively simple, and they mostly rely on substrate deformation or complex parameter design to achieve a three-dimensional effect. The hot pressing molding of the substrate requires high precision and the process control is difficult.

[0005] Therefore, developing new 3D anti-counterfeiting films with low manufacturing difficulty, rich visual effects, and higher anti-counterfeiting performance remains a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a functional film with 3D visual effects and its preparation method. The preparation method has the advantage of simple process, and the functional film obtained by the preparation method has dynamic 3D visual effects and excellent anti-counterfeiting performance.

[0007] To achieve the above-mentioned objectives, the present invention is implemented through the following technical solution:

[0008] In a first aspect, the present invention provides a functional film with 3D visual effects, comprising:

[0009] basal layer;

[0010] A first microstructure array layer is disposed on one side of the substrate layer. The first microstructure array layer is composed of a plurality of first microstructure units, and the plurality of first microstructure units are arranged periodically in a direction parallel to the substrate layer. The distance between two adjacent first microstructure units is P.

[0011] A spacer layer is disposed on the side of the first microstructure array layer away from the substrate layer;

[0012] The second microstructure array layer is disposed on the side of the spacer layer away from the first microstructure array layer. The second microstructure array layer is composed of multiple second microstructure units, and the multiple second microstructure units are arranged periodically in a direction parallel to the substrate layer. The distance between two adjacent second microstructure units is P. The second microstructure unit has a preset offset (Δx, Δy) relative to the first microstructure unit in a plane parallel to the substrate layer; where Δx = m × P / N, Δy = n × P / N, m and n are integers, N is an integer greater than or equal to 2, and Δx and Δy are not simultaneously zero.

[0013] A printed layer is disposed on the side of the substrate layer away from the first microstructure array layer.

[0014] In this application, two microstructure arrays with identical periods (a first microstructure array layer and a second microstructure array layer) are employed, separated by a spacer layer. This allows the second microstructure layer to have an in-plane offset relative to the first layer with a rational frequency division (Δx = m × P / N, Δy = n × P / N). When ambient light is incident from the second microstructure array layer, the two microstructure arrays generate a grating effect. Due to the offset, the phase of the grating fringes is precisely modulated, forming an optical pattern that shifts with the viewing angle. This pattern, under the influence of visual persistence and parallax, presents a 3D stereoscopic image with a sense of depth. Simultaneously, by adjusting the N value (i.e., the denominator of the offset), the fineness of the grating fringes and the depth levels of the 3D image can be controlled, achieving multi-level depth-of-field effects. Based on this, the printed layer located on the side of the base layer away from the first microstructure array layer is used to provide diffuse or transmitted background light: ambient light passes through each layer and shines on the printed layer, forming a uniform or patterned backlight; when the backlight passes through each layer again, it works together with the overlapping grating stripes to significantly enhance the contrast and clarity of the 3D dynamic image. At the same time, the graphic information of the printed layer itself can serve as an additional anti-counterfeiting feature, achieving a dual anti-counterfeiting effect.

[0015] Preferably, the offset Δx = P / 2, Δy = 0.

[0016] Preferably, the thickness d of the spacer layer satisfies: 0.5f ≤ d ≤ 2f, where f is the equivalent focal length of the first microstructure unit or the second microstructure unit.

[0017] Preferably, the thickness of the spacer layer is d = f.

[0018] Preferably, the value of the spacing P is in the range of 1μm ≤ P ≤ 100μm.

[0019] Preferably, the first microstructure unit and / or the second microstructure unit is at least one of a microlens, a microcylindrical lens, a blazed grating, or a sinusoidal grating.

[0020] Preferably, the base layer is a transparent polymer film, and the spacer layer is a transparent resin layer.

[0021] Secondly, the present invention also provides a method for preparing a functional film with 3D visual effects, comprising the following steps:

[0022] S1. Provides the base layer;

[0023] S2. A planar microstructure template is prepared by a UV curing transfer process. The surface of the planar microstructure template has a recessed structure that is complementary to the first microstructure unit, and the spacing between adjacent recessed structures is P. UV curable resin is coated on the surface of the substrate layer, and the planar microstructure template is pressed onto the UV curable resin and cured by UV irradiation. The planar microstructure template is peeled off to form a first microstructure array layer on the substrate layer.

[0024] S3. A transparent resin is coated on the surface of the first microstructure array layer to obtain a spacer layer;

[0025] S4. Apply UV-curable resin to the surface of the spacer layer, press the planar microstructure template onto the UV-curable resin, and control the recessed structure to have a preset offset (Δx, Δy) relative to the first microstructure unit in a plane parallel to the substrate layer, and perform UV irradiation curing; peel off the planar microstructure template to form a second microstructure array layer on the spacer layer.

[0026] S5. A printed layer is formed on the side of the substrate layer away from the first microstructure array layer by a printing process.

[0027] Preferably, in step S3, the thickness of the spacer layer is controlled to be d by a spin coating process.

[0028] Preferably, in step S2 or S4, the UV-curable resin is an acrylate, epoxy, or silicone UV-curable resin, and its refractive index after curing is 1.45 to 1.65.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. This invention provides a functional film with 3D visual effects. It adopts a symmetrical structure with a double-layer microstructure array and a spacer layer. Through the stacking effect of the two-layer microstructure and the in-plane offset design, a 3D image with dynamic displacement with the viewing angle is generated, which has rich visual effects and high anti-counterfeiting performance.

[0031] 2. The preparation method of the present invention adopts a process of two ultraviolet embossing and one coating, which has the advantages of fewer steps and high efficiency, and is suitable for roll-to-roll continuous production. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the present invention.

[0033] In the picture:

[0034] 1. Substrate layer; 2. First microstructure array layer; 21. First microstructure unit; 3. Spacer layer; 4. Second microstructure array layer; 41. Second microstructure unit; 5. Printed layer. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0036] Example 1

[0037] A functional membrane with 3D visual effects, such as Figure 1 As shown, it includes:

[0038] Substrate 1 is a 50μm thick transparent PET film;

[0039] The first microstructure array layer 2, disposed on the substrate layer 1, is composed of multiple first microstructure units 21. Each first microstructure unit 21 is a hemispherical microlens with a radius of curvature R = 30 μm and an equivalent focal length f ≈ 60 μm. The multiple first microstructure units 21 are arranged in a hexagonal periodic pattern in a direction parallel to the substrate layer 1, and the center-to-center distance between two adjacent first microstructure units 21 is P = 40 μm. It should be noted that the equivalent focal length is defined as the position of the equivalent focal plane of the grating-type microstructure unit that produces a focusing effect on perpendicularly incident parallel light. Specifically, a blazed grating or a sinusoidal grating can diffract and converge incident light onto a specific plane, and the vertical distance between this plane and the plane where the microstructure array is located is the equivalent focal length f.

[0040] Spacer layer 3, disposed on the first microstructure array layer 2, is an acrylic transparent resin layer with a thickness d=60μm (d=f).

[0041] The second microstructure array layer 4, disposed on the spacer layer 3, is composed of multiple second microstructure units 41. Each second microstructure unit 41 is also a hemispherical microlens with a radius of curvature R = 30 μm and an equivalent focal length f ≈ 60 μm. The multiple second microstructure units 41 are arranged in a hexagonal periodic pattern in a direction parallel to the substrate layer 1, and the center-to-center distance between two adjacent second microstructure units 41 is P = 40 μm. The offset of the second microstructure unit 41 relative to the first microstructure unit 21 in the plane parallel to the substrate layer 1 is Δx = 20 μm (i.e., P / 2) and Δy = 0.

[0042] The printed layer 5 is located on the side of the base layer 1 away from the first microstructure array layer 2, and is a red letter pattern formed by gravure printing.

[0043] The functional membrane provided in this embodiment is prepared through the following steps:

[0044] S1. Select a 50μm thick PET film, clean the surface with ethanol, and dry it for later use.

[0045] S2. Forming the first microstructure array layer 2 on the substrate layer 1: A micropore array template is prepared on quartz glass using femtosecond laser direct writing combined with wet etching technology. The micropores are hemispherical depressions with a diameter of 40 μm, the center-to-center distance between adjacent micropores is 40 μm, and the depth of the micropores is about 20 μm (corresponding to the height of the microlens). A release agent is coated on the template surface. UV-curable acrylic resin (refractive index 1.52) is dropped onto the surface of the substrate layer 1, and the quartz template is pressed onto the resin. Pressure is applied to fill the micropores of the template with resin, and then the resin is cured by irradiation with a 365nm UV lamp for 2 minutes. The quartz template is peeled off to form the first microstructure array layer 2 on the substrate layer 1.

[0046] S3. Using a spin coating process, transparent acrylic resin is coated onto the surface of the first microstructure array layer 2. The rotation speed and time are controlled to make the wet film thickness 60μm. Then, it is cured with ultraviolet light to obtain a spacer layer 3 with a thickness d=60μm.

[0047] S4. Forming a second microstructure array layer 4 on spacer layer 3: Apply UV-curable acrylate resin to the surface of spacer layer 3, and optically align the quartz template from step S2 with the first microstructure array layer 2: Observe the alignment marks on the first microstructure array layer 2 and the second pressing template through a microscope, manually adjust the template position so that the center of the micropore of the quartz template is offset by 20 μm (i.e., P / 2) relative to the center of the first microstructure unit 21, and the alignment accuracy is better than 0.1P (i.e., 4 μm); press the quartz template onto the resin, and irradiate it with a 365nm UV lamp for 2 min to cure the resin; peel off the quartz template to form the second microstructure array layer 4 on spacer layer 3.

[0048] S5. A printing layer 5 is formed on the side of the substrate layer 1 away from the first microstructure array layer 2 by gravure printing process. The printing layer 5 is a red letter pattern, thus obtaining a functional film.

[0049] The functional film prepared in this embodiment, when observed under transmitted light, shows a clear 3D image floating above a red background. The image moves left and right depending on the viewing angle, exhibiting a dynamic visual effect.

[0050] Example 2

[0051] This embodiment is basically the same as embodiment 1, except that the offset is different.

[0052] Specifically, in step S4, the offset is controlled to be Δx=0 and Δy=20μm (i.e., P / 2). When the fabricated functional film is observed under transmitted light, the 3D image above the red background moves up and down with the viewing angle.

[0053] Example 3

[0054] This embodiment is basically the same as embodiment 1, except that the offset is different and the thickness of the spacer layer 3 is different.

[0055] Specifically, the equivalent focal length f of the first microstructure unit 21 and the second microstructure unit 41 is 60 μm. The thickness d of the spacer layer 3 is 30 μm (i.e., 0.5f). In step S4, the control offset is Δx = 13.33 μm (i.e., P / 3) and Δy = 13.33 μm (i.e., P / 3).

[0056] When the fabricated functional film is observed under transmitted light, two 3D images with different depths of field are displayed above the red background. One layer is suspended higher and the other is suspended lower, exhibiting a multi-level depth of field effect.

Claims

1. A functional film with 3D visual effects, characterized in that, include: Basal layer (1); The first microstructure array layer (2) is disposed on one side of the substrate layer (1). The first microstructure array layer (2) is composed of a plurality of first microstructure units (21), and the plurality of first microstructure units (21) are arranged periodically in a direction parallel to the substrate layer (1). The distance between two adjacent first microstructure units (21) is P. A spacer layer (3) is disposed on the side of the first microstructure array layer (2) away from the substrate layer (1); The second microstructure array layer (4) is disposed on the side of the spacer layer (3) away from the first microstructure array layer (2). The second microstructure array layer (4) is composed of a plurality of second microstructure units (41), and the plurality of second microstructure units (41) are arranged periodically in a direction parallel to the base layer (1). The distance between two adjacent second microstructure units (41) is P. The second microstructure unit (41) has a preset offset (Δx, Δy) relative to the first microstructure unit (21) in a plane parallel to the base layer (1); where Δx = m × P / N, Δy = n × P / N, m and n are integers, N is an integer greater than or equal to 2, and Δx and Δy are not simultaneously zero. The printed layer (5) is located on the side of the substrate layer (1) away from the first microstructure array layer (2).

2. The functional film with 3D visual effects according to claim 1, characterized in that, The offset Δx = P / 2, Δy = 0.

3. The functional film with 3D visual effects according to claim 1, characterized in that, The thickness d of the spacer layer (3) satisfies: 0.5f ≤ d ≤ 2f, where f is the equivalent focal length of the first microstructure unit (21) or the second microstructure unit (41).

4. The functional film with 3D visual effects according to claim 3, characterized in that, The thickness of the spacer layer (3) is d = f.

5. The functional film with 3D visual effects according to claim 1, characterized in that, The value of the spacing P is in the range of 1μm ≤ P ≤ 100μm.

6. The functional film with 3D visual effects according to claim 1, characterized in that, The first microstructure unit (21) and / or the second microstructure unit (41) is at least one of a microlens, a microcylindrical lens, a blazed grating, or a sinusoidal grating.

7. The functional film with 3D visual effects according to claim 1, characterized in that, The base layer (1) is a transparent polymer film, and the spacer layer (3) is a transparent resin layer.

8. A method for preparing a functional film with 3D visual effects as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Provide the base layer (1); S2. A planar microstructure template is prepared by ultraviolet light curing and transcription process. The surface of the planar microstructure template has a concave structure that is complementary to the first microstructure unit (21), and the spacing between adjacent concave structures is P. UV-curable resin is coated on the surface of the substrate layer (1), the planar microstructure template is pressed onto the UV-curable resin, and UV-cured. The planar microstructure template is peeled off to form a first microstructure array layer (2) on the substrate layer (1). S3. A transparent resin is coated on the surface of the first microstructure array layer (2) to obtain a spacer layer (3); S4. Apply UV-curable resin to the surface of the spacer layer (3), press the planar microstructure template onto the UV-curable resin, and control the recessed structure to have a preset offset (Δx, Δy) relative to the first microstructure unit (21) in a plane parallel to the base layer (1), and perform UV irradiation curing; peel off the planar microstructure template to form a second microstructure array layer (4) on the spacer layer (3). S5. A printed layer (5) is formed on the side of the substrate layer (1) away from the first microstructure array layer (2) by a printing process.

9. The method for preparing a functional film with 3D visual effects according to claim 8, characterized in that, In step S3, the thickness of the spacer layer (3) is controlled to be d by spin coating process.

10. The method for preparing a functional film with 3D visual effects according to claim 8, characterized in that, In step S2 or S4, the UV-curable resin is an acrylate, epoxy, or silicone UV-curable resin, and its refractive index after curing is 1.45~1.65.

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