Optical film with anti-fingerprint function and preparation method thereof

Abstract

The invention provides an optical film with an anti-fingerprint function and a preparation method thereof, and belongs to the technical field of optical film materials. The technical problem to be solved is that in the prior art, protection performance and optical performance are difficult to consider at the same time. According to the technical scheme for solving the technical problem, the nano-porous metal oxide coating comprises a base material, a micron-sized patterned primer layer is arranged on the surface of the base material, a periodic microstructure is arranged on the surface of the micron-sized patterned primer layer, and the side, close to the periodic microstructure, of the micron-sized patterned primer layer is covered with a nano-porous metal oxide layer. The micron-sized patterned primer layer and the nano-porous metal oxide layer form a graded micro-nano composite structure, and a low-surface-energy modification layer is arranged on the surface of the nano-porous metal oxide layer; the method is applied to the fields of high-end televisions, vehicle-mounted displays, tablet personal computers and the like.

Description

Technical Field

[0001] This application relates to the field of optical film technology, and in particular to an optical film with anti-fingerprint function and its preparation method. Background Technology

[0002] Mini LED, as a next-generation display technology, boasts advantages such as high brightness, high contrast, and thinness. Its light-emitting chips are typically protected by encapsulating films (such as PMMA and silicone). During use, the surface of the encapsulating film is highly susceptible to fingerprints and grease, affecting display quality and aesthetics. Therefore, it needs to have anti-fingerprint (AF) functionality.

[0003] Currently, anti-fingerprint functionality is achieved primarily through two methods: adding modified materials within the encapsulation film (internal addition) or coating the encapsulation surface with a functional coating (external coating). Among these, external coating technology has been widely studied due to its flexibility and efficiency. Existing technologies often employ external anti-fingerprint coatings based on constructing a rough surface using silica (SiO2) nanoparticles, followed by the use of fluorinated silanes to reduce surface energy. For example, some patent documents disclose a scheme involving the growth of silica micro / nano structures via vapor deposition followed by hydrophobic modification. Another approach utilizes functionalized cage-like silsesquioxanes (POSS) to form a silica-like network via physical vapor deposition.

[0004] However, these existing technical solutions have the following limitations: First, the coating material based on silica has a poor balance between hardness and toughness, and its wear resistance is often insufficient, making it difficult to withstand long-term wiping or friction; second, the adhesion between the nanostructure constructed solely by physical or vapor deposition and the substrate is limited, posing a risk to durability; third, in order to achieve better overall performance (such as anti-reflection and anti-reflection), it is often necessary to stack it with other functional film layers, which leads to complex processes, increased costs, and the interlayer interface may cause new reliability problems.

[0005] Therefore, there is an urgent need in this field to develop a surface protection solution for Mini LED packaging that combines excellent hydrophobicity and oleophobicity, high light transmittance, outstanding abrasion resistance and strong adhesion, and simplifies process integration. Summary of the Invention

[0006] To address the aforementioned technical problems, this application proposes an optical film with anti-fingerprint functionality and a method for its preparation.

[0007] The technical solution adopted in this application is as follows: an optical film with anti-fingerprint function, comprising a substrate, wherein a micron-scale patterned primer layer is disposed on the surface of the substrate, a periodic microstructure is disposed on the surface of the micron-scale patterned primer layer, a nanoporous metal oxide layer is covered on the side of the micron-scale patterned primer layer near the periodic microstructure, the micron-scale patterned primer layer and the nanoporous metal oxide layer constitute a hierarchical micro-nano composite structure, and a low surface energy modification layer is disposed on the surface of the nanoporous metal oxide layer.

[0008] Furthermore, the periodic microstructure is a cylindrical array, a pyramidal array, or a groove array.

[0009] Furthermore, the nanoporous metal oxide layer includes a non-silicon-based metal oxide, which includes any one or two of titanium dioxide, zinc oxide, and cerium oxide.

[0010] Furthermore, the low surface energy modification layer is a fluorinated silane reagent.

[0011] Furthermore, the fluorinated silane reagent is 1H,1H,2H,2H-perfluorooctyltriethoxysilane.

[0012] Furthermore, the porosity of the nanoporous metal oxide layer varies in a gradient along the thickness direction.

[0013] A method for preparing an optical film with anti-fingerprint function as described above includes the following steps: Step 1: Using nanoimprint lithography, the micron-scale patterned primer layer is deposited on the surface of the substrate; Step 2: Using the sol-gel method, grow the nanoporous metal oxide layer on the side of the micron-scale patterned primer layer near the periodic microstructure; Step 3: Using a surface modification process, a low surface energy modifier is bonded to the surface of the nanoporous metal oxide layer to form the low surface energy modified layer.

[0014] Further, prior to step 1, the surface of the substrate is subjected to plasma pretreatment, wherein the plasma includes at least one of argon, oxygen, or carbon tetrafluoride.

[0015] Furthermore, step 2 also includes the following steps: Step 21: Prepare a sol mainly composed of non-silicon-based metal oxide precursors; Step 22: The sol is coated onto the side of the micron-scale patterned primer layer near the periodic microstructure, and then heat-treated to allow the nanoporous metal oxide layer to grow on the side of the micron-scale patterned primer layer near the periodic microstructure.

[0016] Furthermore, in step 3, the surface modification process is a vapor deposition method.

[0017] The advantages of this application over the prior art are as follows: combining a "micron-scale patterned primer layer" with a "nanoporous metal oxide layer", the micron-scale patterned primer layer and the periodic microstructure provide a mechanically stable macro framework and a large structural height, the nanooporous metal oxide layer not only contributes to the secondary roughness, but its high hardness characteristics also greatly improve the overall wear resistance of the coating, and the hierarchical micro-nano composite structure formed by the two makes the adhesion extremely strong. This hierarchical micro-nano composite structure, together with the low surface energy modification layer, is expected to achieve superhydrophobic and oleophobic effects while maintaining high light transmittance; The use of "non-silicon-based metal oxides" as nanostructure layer materials fundamentally distinguishes them from the silicon dioxide or POSS systems commonly used in existing technologies. The fabrication process adopts a "patterning first, followed by wet chemical growth" approach, which is significantly different from the mainstream vapor deposition growth technology. By ingeniously designing the porosity of the nanoporous metal oxide layer, excellent anti-fingerprint and anti-reflection functions can be achieved simultaneously within a single film layer. This avoids the complex process, high cost, and potential risk of interlayer delamination associated with traditional multilayer film stacking, making it more conducive to industrial applications. The sol-gel method and nanoimprint technology used are both relatively mature, with a wide process window, easy parameter control, and good compatibility with existing display device manufacturing lines, facilitating technology transfer and promotion. Attached Figure Description

[0018] The following description, in conjunction with the accompanying drawings, further illustrates this application: Figure 1 This is a cross-sectional view of the optical film in this application; Figure 2 This is a schematic diagram of the cylindrical array-type periodic microstructure in this application; Figure 3 This is a flowchart of the method for preparing the optical film in this application; Figure 4 This is a schematic diagram of the structure of the nanoporous metal oxide layer in this application; In the figure: 1 is the substrate, 2 is the micron-scale patterned primer layer, 21 is the periodic microstructure, 3 is the nanoporous metal oxide layer, 4 is the low surface energy modification layer, A is the high porosity region, B is the medium porosity region, and C is the low porosity region. Detailed Implementation

[0019] like Figures 1 to 4As shown, this application provides an optical film with anti-fingerprint function, including a substrate 1. A micron-scale patterned primer layer 2 is disposed on the surface of the substrate 1. Periodic microstructures 21 are disposed on the surface of the micron-scale patterned primer layer 2. The periodic microstructures 21 are cylindrical arrays, pyramidal arrays, or trench arrays, with a period of 2-20 μm and a height or depth of 1-10 μm, to achieve a balance between hydrophobicity and optical performance. In this embodiment, the micron-scale patterned primer layer 2 is used as the skeleton and foundation of the entire hierarchical structure. A nanoporous metal oxide layer 3 is covered on the side of the micron-scale patterned primer layer 2 closest to the periodic microstructures 21. The nanoporous metal oxide layer 3 covers and completely adheres to the surface of the micron-scale patterned primer layer 2, forming a strong mechanical interlock between the two, and together constituting a hierarchical micro-nano composite structure with a large-size framework and small-size roughness. The hierarchical micro-nano composite structure is used to achieve the superhydrophobic, oleophobic, and high light transmittance performance of the optical film.

[0020] The nanoporous metal oxide layer 3 comprises a non-silicon-based metal oxide, which includes any one or two of titanium dioxide, zinc oxide, and cerium oxide. The thickness of the nanoporous metal oxide layer 3 is 50 nm-300 nm, and the porosity is 30%-60%. This range provides sufficient roughness and optical performance control space while ensuring mechanical strength. The porosity of the nanoporous metal oxide layer 3 varies gradually along its thickness direction, for example, the porosity gradually decreases from near the micron-scale patterned primer layer 2 to away from the micron-scale patterned primer layer 2, thereby achieving a gradient transition of refractive index within the same physical layer and integrating anti-reflection function. A low surface energy modification layer 4 is disposed on the surface of the nanoporous metal oxide layer 3. The low surface energy modification layer 4 is chemically bonded to the nanoporous metal oxide layer 3, which can significantly reduce the free energy of the structural surface. The low surface energy modification layer 4 is a fluorinated silane reagent, including 1H,1H,2H,2H-perfluorooctyltriethoxysilane.

[0021] A method for preparing an optical film with anti-fingerprint function as described above includes the following steps: Step 1: The surface of the substrate 1 is subjected to plasma pretreatment, wherein the plasma includes at least one of argon, oxygen, or carbon tetrafluoride. Then, the micron-scale patterned primer layer 2 is formed on the surface of the substrate 1 using nanoimprinting technology (preferably ultraviolet nanoimprinting technology). Step 2: Using the sol-gel method, a stable sol is first prepared, primarily composed of a non-silicon-based metal oxide precursor (such as tetrabutyl titanate for TiO2). Then, the sol is coated (e.g., spin-coated, dip-coated) onto the side of the micron-scale patterned primer layer 2 near the periodic microstructure 21, and heat-treated to gel the sol and form a crystalline or amorphous oxide layer with a nanoporous structure. This process enables the nanolayer to achieve a tight molecular-scale bond with the micron-scale primer, thereby allowing the nanoporous metal oxide layer 3 to grow on the side of the micron-scale patterned primer layer 2 near the periodic microstructure 21. Specifically, when the non-silicon-based metal oxide is titanium dioxide, the precursor is tetrabutyl titanate; when the non-silicon-based metal oxide is zinc oxide, the precursor is zinc acetate.

[0022] Step 3: Through a surface modification process, a low surface energy modifier is bonded to the surface of the nanoporous metal oxide layer 3 to form a monolayer or sub-monolayer low surface energy modified layer 4. The surface modification process preferably employs vapor deposition, performed under heating and a vacuum or inert atmosphere to ensure that the modifier molecules can penetrate deep into the nanopores and achieve uniform bonding.

[0023] The following are specific embodiments of this application.

[0024] Example 1: Basic Implementation This application provides a basic micro / nano composite anti-fingerprint film and its preparation method. Please refer to [link to relevant documentation]. Figure 1 and Figure 2 The structure shown. A PMMA (polymethyl methacrylate) encapsulation film for Mini LEDs is selected as substrate 1. It undergoes routine cleaning (such as solvent ultrasonic cleaning) and drying; as... Figure 2 As shown, UV-curable resin is coated onto substrate 1. Nanoimprinting is performed using a template with a periodic array of micropits on its surface under UV irradiation. After demolding, a micron-scale patterned primer layer 2 with an inverted microcylindrical array is formed on substrate 1. The period of the cylindrical array is 10 μm and the height is 3 μm.

[0025] Using the sol-gel method, tetrabutyl titanate was dissolved in anhydrous ethanol as a precursor. Glacial acetic acid and deionized water were added with stirring, and stirring continued to form a uniform and stable pale yellow titanium dioxide sol. The titanium dioxide sol was spin-coated onto the surface of a patterned primer, followed by heat treatment (e.g., holding at 250°C for 1 hour) to form a nanoporous titanium dioxide layer. Using vapor deposition, 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES) was used as a modifier to surface-treat the nanoporous titanium dioxide layer under heating conditions, forming a low surface energy modified layer 4.

[0026] In summary, the film prepared by this process is expected to have better hydrophobicity and abrasion resistance than ordinary flat coatings.

[0027] Example 2: High-performance optimized implementation This embodiment introduces pretreatment and process optimization based on Embodiment 1 to further improve performance. The process flow is as follows: Figure 3 As shown.

[0028] The cleaned substrate 1 is placed on a tray in the plasma reaction chamber. Argon gas is introduced through the inlet to generate plasma glow at a specific power, treating the surface of substrate 1 for tens of seconds, and then the pressure is restored to normal through the evacuation port. This treatment effectively activates the surface. Subsequently, a micro-cylindrical array with smaller period, diameter, and height (e.g., period of approximately 4 μm and height of approximately 2 μm) is formed using a higher precision template.

[0029] The sol-gel aging time and heat treatment procedure in Example 1 were optimized by, for example, using a stepped heating procedure: first pre-curing at a lower temperature (e.g., 150°C), then slowly increasing to a higher temperature (e.g., 280°C) for final heat treatment. This process helps to form a nanoporous metal oxide layer 3 with better crystallinity and a more uniform pore structure. Subsequent steps are the same as in Example 1, but the temperature and time of vapor deposition can be optimized.

[0030] Through the above optimizations, the overall performance of the film is expected to be significantly improved, including: a static water contact angle reaching superhydrophobic level, excellent oleophobicity, extremely high light transmittance, abrasion resistance reaching high pencil hardness level, and excellent adhesion in cross-cut adhesion test.

[0031] Example 3: Implementation of Integrated Anti-reflection Function This embodiment demonstrates how to achieve single-layer integration of anti-fingerprint and anti-reflective functions. A structural schematic diagram is shown below. Figure 4 As shown.

[0032] The substrate pretreatment, patterned primer formation, and surface modification steps of Example 2 were repeated. After completing the above steps, a nanoporous titanium oxide layer with gradient porosity was prepared, such as... Figure 4 As shown, the goal is to form nanolayers with gradually decreasing porosity along the thickness direction. Specifically, this can be achieved by formulating a series of sols with different expected porosities (e.g., by adjusting the amount of water used in hydrolysis), and then using a layer-by-layer spin-coating method to stack them. Finally, a uniform high-temperature heat treatment is used to fuse the interfaces of each layer, forming a gradient structure with continuously decreasing porosity. This structure can generate an effective refractive index gradient.

[0033] The film layer designed in this way is expected to maintain the superhydrophobic, oleophobic, and highly wear-resistant properties of Example 2, while its surface reflectivity in the visible light band can be significantly suppressed, achieving a significant anti-reflection effect, thereby improving the contrast and color performance of the display device.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An optical film with anti-fingerprint function, comprising a substrate (1), characterized in that: The substrate (1) has a micron-scale patterned primer layer (2) on its surface. The micron-scale patterned primer layer (2) has a periodic microstructure (21) on its surface. The side of the micron-scale patterned primer layer (2) close to the periodic microstructure (21) is covered with a nanoporous metal oxide layer (3). The micron-scale patterned primer layer (2) and the nanoporous metal oxide layer (3) constitute a hierarchical micro-nano composite structure. The nanoporous metal oxide layer (3) has a low surface energy modification layer (4) on its surface.

2. The optical film with anti-fingerprint function according to claim 1, characterized in that: The periodic microstructure (21) is a cylindrical array, a pyramidal array, or a groove array.

3. An optical film with anti-fingerprint function according to claim 1 or 2, characterized in that: The nanoporous metal oxide layer (3) includes non-silicon-based metal oxides, which include any one or two of titanium dioxide, zinc oxide, and cerium oxide.

4. The optical film with anti-fingerprint function according to claim 3, characterized in that: The low surface energy modification layer (4) is a fluorinated silane reagent.

5. An optical film with anti-fingerprint function according to claim 4, characterized in that: The fluorinated silane reagent is 1H,1H,2H,2H-perfluorooctyltriethoxysilane.

6. An optical film with anti-fingerprint function according to claim 4 or 5, characterized in that: The porosity of the nanoporous metal oxide layer (3) varies in a gradient along the thickness direction.

7. A method for preparing an optical film with anti-fingerprint function as described in claim 6, characterized in that: Includes the following steps: Step 1: Using nanoimprinting technology, the micron-scale patterned primer layer (2) is formed on the surface of the substrate (1); Step 2: Using the sol-gel method, the nanoporous metal oxide layer (3) is grown on the side of the micron-scale patterned primer layer (2) near the periodic microstructure (21). Step 3: Using a surface modification process, a low surface energy modifier is bonded to the surface of the nanoporous metal oxide layer (3) to form the low surface energy modified layer (4).

8. The preparation method according to claim 7, characterized in that: Before step 1, the surface of the substrate (1) is subjected to plasma pretreatment, wherein the plasma includes at least one of argon, oxygen or carbon tetrafluoride.

9. The preparation method according to claim 8, characterized in that: Step 2 also includes the following steps: Step 21: Prepare a sol mainly composed of non-silicon-based metal oxide precursors; Step 22: The sol is coated on the side of the micron-scale patterned primer layer (2) near the periodic microstructure (21) and heat-treated to grow the nanoporous metal oxide layer (3) on the side of the micron-scale patterned primer layer (2) near the periodic microstructure (21).

10. The preparation method according to claim 9, characterized in that: In step 3, the surface modification process is vapor deposition.

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