Vehicle-mounted display optical diffusion film and preparation method thereof

Abstract

The invention relates to the field of optical diffusion films, in particular to a vehicle-mounted display optical diffusion film and a preparation method thereof.The vehicle-mounted display optical diffusion film comprises a base material layer and a diffusion layer, and the diffusion layer is prepared from, by weight, 60-80 parts of water-soluble UV curing PUA resin, 5-20 parts of modified zinc oxide particles, 1-3 parts of photoinitiator, 0.1-0.5 part of flatting agent and 20-40 parts of deionized water; the particle size of the zinc oxide nanoparticles is 1-3 [mu] m; the base material layer comprises PMMA (polymethyl methacrylate). The PMMA and the water-soluble UV curing PUA resin are added, the PMMA provides a low-absorption and low-scattering transparent substrate, the PUA resin can form a highly-transparent film after UV curing, the problems of haze increase and light transmittance decrease caused by solvent volatilization residues can be remarkably reduced by using a water-soluble system, moisture can be completely volatilized after curing, and the film has the advantages that the film is transparent, and the film has good transparency. Therefore, the vehicle-mounted display optical diffusion film with high light transmittance is prepared.

Description

Technical Field

[0001] The present application relates to the field of optical diffusion films, and in particular to an optical diffusion film for a vehicle display and a preparation method thereof. Background Art

[0002] With the continuous development of the automotive industry, the intelligence and comfort of in-vehicle equipment have become important development directions. As the key interface for human-machine interaction in the car, the performance of in-vehicle displays is crucial to improving the driving experience and safety. Optical diffuser films, as a key component of in-vehicle displays, can improve light propagation, making the display more uniform and soft, reducing glare and reflections, and enhancing visual quality. High-quality optical diffuser films help reduce driver visual fatigue and enhance information reading accuracy, playing a significant role in improving driving safety. At the same time, they can enhance the sense of technology and luxury in the car, meeting consumers' demand for a high-quality driving environment.

[0003] However, the harsh lighting conditions in vehicles, especially those under strong direct sunlight, place extremely high demands on the readability of displays under strong sunlight. Low transmittance limits color expression and contrast, making it difficult to meet the growing demand for high-end displays such as high resolution, high brightness, HDR, and AR-HUD integration. Therefore, there is an urgent need for an optical diffuser film with high transmittance for automotive displays. Summary of the Invention

[0004] In order to improve the light transmittance of an optical diffuser film for a vehicle display, the present application provides an optical diffuser film for a vehicle display and a preparation method thereof.

[0005] In a first aspect, the present application provides an optical diffuser film for a vehicle display, which adopts the following technical solution: An optical diffusion film for a vehicle display includes a substrate layer and a diffusion layer. The diffusion layer comprises the following components in parts by weight: 60-80 parts of a water-soluble UV-curable PUA resin, 5-20 parts of modified zinc oxide particles, 1-3 parts of a photoinitiator, 0.1-0.5 parts of a leveling agent, and 20-40 parts of deionized water. The zinc oxide nanoparticles have a particle size of 1-3 μm. The substrate layer comprises PMMA.

[0006] By adopting the above technical solution, PMMA itself has extremely high intrinsic transmittance, providing a transparent substrate with low absorption and low scattering. By adding water-soluble UV-curable PUA resin as a film-forming substance, the PUA resin can form a highly transparent and tough film after UV curing. In addition, the use of a water-soluble system can significantly reduce the problems of micropores, increased haze and decreased transmittance caused by residual solvent volatilization compared to traditional organic solvent systems. After curing, the moisture can be completely evaporated, leaving a pure and transparent resin network. The addition of modified zinc oxide particles can be evenly distributed in the water-soluble UV-curable PUA resin, and by optimizing the refractive index matching of the particle-resin interface, the interface reflection loss is significantly reduced. The small-sized zinc oxide particles mainly induce efficient Rayleigh scattering, achieving uniform light diffusion while minimizing light blocking, thereby preparing a vehicle-mounted display light diffusion film with high transmittance.

[0007] When the particle size of zinc oxide particles is too small, the zinc oxide particles tend to agglomerate, forming optical defects, significantly increasing the light loss path within the film, resulting in a decrease in the transmittance of the optical diffuser film. When the particle size of zinc oxide particles is too large, the light scattering ability decreases sharply, and large-sized zinc oxide particles settle quickly in thin coatings due to gravity. At the same time, they are more likely to form micron-sized aggregates during the leveling process, resulting in defects such as orange peel and shrinkage in the optical diffuser film, reducing optical uniformity.

[0008] Preferably, the preparation of the modified zinc oxide particles comprises the following steps: S1: A certain amount of zinc oxide particles was mixed with water to prepare a zinc oxide particle aqueous suspension with a mass concentration of 5.8%, potassium aluminum sulfate (1.8% by mass of the zinc oxide particles) was added, and the mixture was stirred at 3200 r / min for 1 hour. Ammonia water was added to adjust the pH of the suspension to 8.5, and the mixture was heated to 88°C and stirred at 150 r / min for 25 minutes. The mixture was then ultrasonically treated at 300W for 2 minutes, and ammonium persulfate (0.12% by mass of the suspension) was added. After stirring, the mixture was kept warm at 50°C for 15 minutes, and then vacuum filtered and dried in a vacuum drying oven at 80°C to obtain activated zinc oxide particles. S2: Silane coupling agent KH-550 was added to distilled water and mixed, and then added to anhydrous ethanol to prepare a solution with a mass fraction of silane coupling agent KH-550 of 3.5%, wherein the volume ratio of distilled water to anhydrous ethanol was 1:3. The solution was allowed to stand for 2 hours, and then the activated zinc oxide particles were added. The mixture was ultrasonically dispersed for 2 hours, and then the pH was adjusted to 3.5 with glacial acetic acid. The mixture was stirred at a speed of 1500 r / min for 2 hours, and then vacuum dried to obtain modified zinc oxide particles.

[0009] By adopting the above technical solution, in the S1 activation stage, potassium aluminum sulfate hydrolysis coating and ammonium persulfate oxidation are used to form a dense passivation layer on the surface of zinc oxide, inhibiting photocatalytic activity and increasing the hydroxyl density; in the S2 coupling stage, the silane coupling agent KH-550 is covalently bonded to the activated particles under acidic conditions to construct an amino organic coating layer, which not only eliminates nano-agglomeration and ensures dispersion stability, but also forms a gradient transition interface between zinc oxide (high refractive index) and resin (low refractive index), significantly reducing scattering loss, while greatly enhancing compatibility with the PUA matrix, providing dual guarantees for high transmittance and long-term stability.

[0010] Preferably, the photoinitiator is at least one of TPO-L and benzoylformate.

[0011] Preferably, the photoinitiator is TPO-L.

[0012] By adopting the above technical solution, after TPO-L absorbs ultraviolet light, the phosphoryl group in the molecule undergoes homolysis to generate phosphoryl free radicals with high reactivity, which directly initiate free radical polymerization of the acrylate double bonds in the water-soluble UV-curable PUA resin.

[0013] Under the excitation of ultraviolet light, the carbonyl group in the benzoyl formate molecule captures the hydrogen on the adjacent carbon to generate benzoyl radicals and carboxylic acid radicals. The former initiates monomer polymerization, and the latter partially decomposes to produce carbon dioxide, which promotes rapid curing of the coating surface.

[0014] As a photoinitiator, TPO-L can specifically avoid the shielding of short-wave UV by modified zinc oxide particles, and efficiently initiate the cross-linking polymerization of acrylate double bonds in water-soluble PUA resin to form a three-dimensional cured network; its long-wave penetrability ensures deep and uniform curing of systems containing a high proportion of inorganic fillers. At the same time, its low yellowing properties maintain the color stability of the optical film, which is conducive to the preparation of optical diffusion films with high light transmittance. Therefore, TPO-L is preferred as a photoinitiator.

[0015] Preferably, the leveling agent is at least one of fluorosilicone modified polyurethane acrylate and a copolymer of 2-methyl methacrylate and butyl acrylate.

[0016] Preferably, the leveling agent is fluorosilicone modified polyurethane acrylate.

[0017] By adopting the above technical solution, the surface tension of the copolymer of 2-methyl methacrylate and butyl acrylate is similar to that of water-soluble UV-curable PUA resin systems, allowing it to be evenly dispersed in the coating. By reducing the surface tension gradient within the system, it inhibits local shrinkage caused by solvent volatilization or component migration during the curing process, thereby reducing defects such as orange peel and brush marks. In addition, the copolymer can be adsorbed on the surface of modified zinc oxide particles, reducing the interfacial tension between the modified zinc oxide particles and the resin, preventing local surface tension abnormalities caused by filler agglomeration, and improving the uniformity of the coating.

[0018] The synergistic effect of the fluorocarbon segments and siloxane linkages in fluorosilicone-modified polyurethane acrylates results in extremely low surface energy, effectively reducing the system's surface tension and promoting coating leveling. Furthermore, the acrylate double bonds in the fluorosilicone-modified polyurethane acrylates crosslink to form a three-dimensional network, anchoring the fluorosilicone segments within the diffusion layer and reducing the probability of migration or volatilization during the curing process. Furthermore, the polyurethane-acrylate structure of the fluorosilicone-modified polyurethane acrylates enhances the mechanical properties of the optical diffuser film, achieving a dual "leveling and enhancement" effect.

[0019] The benzoyl radicals and phosphoryl radicals generated by the decomposition of TPO-L under ultraviolet light are highly reactive and can directly undergo addition reactions with the acrylate double bonds in the fluorosilicone-modified polyurethane acrylate, initiating chain polymerization. This allows the distribution of the modified zinc oxide particles to be quickly "frozen" after the water-soluble UV-curing PUA resin is leveled, reducing the probability of agglomeration due to solvent volatilization or molecular movement during the curing process, thereby effectively improving the transmittance of the optical diffusion film.

[0020] Preferably, the diffusion layer has a thickness of 12-20 μm.

[0021] When the diffusion layer is too thin, the number of scattering particles is insufficient, resulting in uneven light diffusion and difficulty eliminating backlight hotspots and glare. The coating also suffers from poor leveling and is prone to defects. Furthermore, the film lacks mechanical strength and is prone to cracking and peeling under vehicle vibration. If the diffusion layer is too thick, light transmittance is significantly reduced, haze is excessive, resulting in a whitish, blurry image, and insufficient curing can cause internal stress accumulation in the coating, leading to warping or cracking under thermal shock.

[0022] In a second aspect, the present application provides a method for preparing an optical diffusion film for a vehicle display, which adopts the following technical solution: A method for preparing an optical diffusion film for a vehicle display comprises the following steps: S1: Plasma-treating PMMA to obtain plasma-treated PMMA; S2: Weigh the formulated amount of water-soluble UV-curable PUA resin and mix it with deionized water. Stir at 800 rpm for 10 minutes to obtain a resin solution. Mix the modified zinc oxide particles with the resin solution. Then, add the formulated amount of photoinitiator and leveling agent and mix to obtain a suspension. S3: The suspension is coated on the plasma-treated PMMA, which is kept in the dark and cured by ultraviolet irradiation to obtain an optical diffusion film for a vehicle display.

[0023] By adopting the above technical solution, PMMA is first subjected to isoelectronic treatment to effectively improve the surface wettability of PMMA. Then, water-soluble UV-curable PUA resin is dissolved in deionized water and modified zinc oxide particles are added to effectively promote the uniform dispersion of modified zinc oxide particles and reduce the probability of modified zinc oxide particle agglomeration. The addition of leveling agent can reduce the surface tension of the resin and help form a smooth and uniform optical diffusion film. Finally, the diffusion layer is cured under the initiation of ultraviolet light to produce a high-transmittance vehicle display optical diffusion film.

[0024] In summary, this application includes at least one of the following beneficial technical effects: 1. This application utilizes PMMA's inherently high intrinsic transmittance to provide a low-absorption, low-scattering transparent substrate. Furthermore, by adding a water-soluble UV-curable PUA resin as a film-forming substance, the PUA resin forms a highly transparent, tough film after UV curing. Furthermore, the use of a water-soluble system significantly reduces the problems of residual micropores, increased haze, and decreased transmittance caused by solvent evaporation compared to traditional organic solvent systems. After curing, the water evaporates completely, leaving behind a pure, transparent resin network. 2. The modification of zinc oxide particles in this application not only eliminates nano-agglomeration and ensures dispersion stability, but also forms a gradient transition interface between zinc oxide (high refractive index) and resin (low refractive index), significantly reducing scattering losses and greatly enhancing compatibility with the PUA matrix, providing dual guarantees for high light transmittance and long-term stability. 3. In this application, TPO-L is combined with fluorosilicone-modified polyurethane acrylate. The benzoyl radicals and phosphoryl radicals generated by the decomposition of TPO-L under ultraviolet light have high reactivity and can directly undergo addition reaction with the acrylate double bonds in the fluorosilicone-modified polyurethane acrylate, initiating chain polymerization. After the water-soluble UV-curable PUA resin is leveled, the distribution state of the modified zinc oxide particles can be quickly "frozen", reducing the probability of agglomeration due to solvent volatilization or molecular movement during the curing process, thereby effectively improving the transmittance of the optical diffusion film. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the structure of the optical diffusion film for a vehicle display according to an embodiment of the present application.

[0026] In the figure: 1. PMMA substrate layer; 2. diffusion layer; 3. modified zinc oxide particles. DETAILED DESCRIPTION

[0027] The raw materials in this application include the following parts: Water-soluble UV-curable PUA resin: water-soluble UV-curable PUA resin model SEAPUR 33G41 produced by Shandong Shoucheng Chemical Co., Ltd.; water-soluble UV-curable PUA resin with 99% active ingredients produced by Green Union (Jining) Chemical Technology Co., Ltd.; zinc oxide nanoparticles: This application takes zinc oxide with particle sizes of 1μm and 3μm produced by Hebei Guangtuo Welding Materials Co., Ltd., zinc oxide with a particle size of 0.5μm produced by Nangong Jiuxin New Materials Technology Co., Ltd., and zinc oxide with a particle size of 10μm produced by Hebei Teng Bimetallic Materials Co., Ltd. as examples.

[0028] TPO-L: a commercially available product with CAS number 84434-11-7; Benzoyl formate: a commercially available product with CAS number 15206-55-0; Copolymer of methyl 2-methacrylate and butyl acrylate: a commercially available product with CAS number 25852-37-3; Fluorosilicone modified polyurethane acrylate: This application takes the fluorosilicone modified polyurethane acrylate with an effective ingredient content of 98% produced by Dongguan Inoue New Materials Development Co., Ltd. as an example.

[0029] The present application is further described in detail below with reference to the following examples and comparative examples.

[0030] Example 1 An optical diffusion film for a vehicle display includes a PMMA substrate layer and a diffusion layer. The diffusion layer includes the following components: 70g of water-soluble UV-curable PUA resin, 13g of modified zinc oxide particles, 2g of water-soluble TPO-L, 0.3g of fluorosilicone-modified polyurethane acrylate, and 30g of deionized water.

[0031] A method for preparing an optical diffusion film for a vehicle display comprises the following steps: S1: Plasma-treating PMMA to obtain plasma-treated PMMA; S2: Weigh the formulated amount of water-soluble UV-curable PUA resin and mix it with deionized water. Stir at 800 rpm for 10 minutes to obtain a resin solution. Mix the modified zinc oxide particles with the resin solution. Then, add the formulated amount of photoinitiator and leveling agent and mix to obtain a suspension. S3: The suspension is coated on the plasma-treated PMMA, which is kept in the dark and cured by ultraviolet irradiation to obtain an optical diffusion film for a vehicle display.

[0032] The thickness of the PMMA substrate is 50-100 μm, the thickness of the diffusion membrane is 17 μm, the particle size of the modified zinc oxide particles is 3 nm, and the preparation method of the modified zinc oxide particles includes the following steps: S1: A certain amount of zinc oxide particles was mixed with water to prepare a zinc oxide particle aqueous suspension with a mass concentration of 5.8%, potassium aluminum sulfate (1.8% by mass of the zinc oxide particles) was added, and the mixture was stirred at 3200 r / min for 1 hour. Ammonia water was added to adjust the pH of the suspension to 8.5, and the mixture was heated to 88°C and stirred at 150 r / min for 25 minutes. The mixture was then ultrasonically treated at 300W for 2 minutes, and ammonium persulfate (0.12% by mass of the suspension) was added. After stirring, the mixture was kept warm at 50°C for 15 minutes, and then vacuum filtered and dried in a vacuum drying oven at 80°C to obtain activated zinc oxide particles. S2: Silane coupling agent KH-550 was added to distilled water and mixed, and then added to anhydrous ethanol to prepare a solution with a mass fraction of silane coupling agent KH-550 of 3.5%, wherein the volume ratio of distilled water to anhydrous ethanol was 1:3, and the solution was allowed to stand for 2 hours. Then, activated zinc oxide particles were added, ultrasonically dispersed for 2 hours, and then glacial acetic acid was used to adjust the pH to 3.5. The solution was stirred at 1500 r / min for 2 hours, and then vacuum dried to obtain modified zinc oxide particles. Example 2-3 In Example 2-3, based on the preparation method of Example 1, the components of the diffusion layer were adjusted. The specific adjustments are shown in Table 1.

[0033] Comparative Examples 1-3 Comparative Examples 1-3 are based on the preparation method of Example 1, but the components of the diffusion layer are adjusted. The specific adjustments are shown in Table 1.

[0034] Performance testing The optical diffusion films of Examples 1-3 and Comparative Examples 1-3 were analyzed, and the specific detection methods are as follows: 1. Transmittance and haze The transmittance and haze of the optical diffusion film were tested in accordance with the national standard GB / T 2410-2008.

[0035] According to the above detection method, the test results of Examples 1-3 and Comparative Examples 1-3 were obtained, as shown in Table 1 below.

[0036] Table 1 Diffusion layer components and performance test table of Examples 1-3 and Comparative Examples 1-3 Referring to Table 1, by comparing Examples 1-3 and Comparative Examples 1-3, it can be seen that the transmittance and haze of the optical diffusion film of Examples 1-3 are significantly higher than those of Comparative Examples 1-3. This may be because PMMA itself has extremely high intrinsic transmittance, providing a transparent substrate with low absorption and low scattering. By adding water-soluble UV-curable PUA resin as a film-forming substance, the PUA resin can form a highly transparent and tough film after UV curing. In addition, the use of a water-soluble system can significantly reduce the problems of micropores, increased haze and decreased transmittance caused by residual solvent after volatilization compared to the traditional organic solvent system. After curing, the moisture can be completely evaporated, leaving a pure and transparent resin network.

[0037] Example 4 Example 4 Based on the preparation method of Example 1, the particle size of the zinc oxide particles was adjusted, and the specific adjustment is shown in Table 2.

[0038] Comparative Examples 4-5 Comparative Example 4-5 Based on the preparation method of Example 1, the particle size of the zinc oxide particles was adjusted. The specific adjustment is shown in Table 2.

[0039] The optical diffusion films of Example 4 and Comparative Examples 4-5 were subjected to the above-mentioned performance tests, and the test results are shown in Table 2.

[0040] Table 2 Particle size and performance test table of zinc oxide particles in Example 1, Examples 4-5 and Comparative Examples 4-5 Referring to Table 2, a comparison of Example 1, Example 4, and Comparative Examples 4-5 shows that when the particle size of the modified zinc oxide particles is between 1 and 3 μm, and particularly when the particle size of the modified zinc oxide particles is 15 nm, the transmittance of the resulting optical diffuser film is optimal. This may be because when the particle size of the zinc oxide particles is too small, the zinc oxide particles tend to agglomerate, forming optical defects, significantly increasing the light loss path within the film, and resulting in a decrease in the transmittance of the optical diffuser film. When the particle size of the zinc oxide particles is too large, the light scattering ability decreases sharply, and large-sized zinc oxide particles settle rapidly in thin coatings due to gravity. Furthermore, during the leveling process, micron-sized aggregates are more likely to form, resulting in defects such as orange peel and shrinkage craters in the optical diffuser film, reducing optical uniformity.

[0041] Comparative Example 6 Comparative Example 6: Based on the preparation method of Example 1, 13 g of modified zinc oxide particles were replaced with 13 g of unmodified zinc oxide particles, and the other conditions remained unchanged.

[0042] Performance testing The optical diffusion films of Example 1 and Comparative Example 6 were analyzed, and the specific detection methods are as follows: Elongation at break The elongation at break of the optical diffusion film was tested in accordance with the national standard GB / T 13541-1992.

[0043] According to the above detection method, the test results of Example 1, Examples 4-5 and Comparative Examples 4-5 were obtained, as shown in Table 3 below.

[0044] Table 3 Performance test table of Example 1 and Comparative Example 6 project Example 1 Comparative Example 6 Transmittance / % 93.2 68.9 Longitudinal elongation at break / % 157 123 Transverse elongation at break / % 165 121 Referring to Table 3, by comparing Example 1 and Comparative Example 6, it can be seen that the performance of the optical diffusion film obtained in Example 1 is better than that of the optical diffusion film in Comparative Example 6. This may be because the modified zinc oxide particles not only effectively eliminate nano-agglomeration and ensure dispersion stability, but also form a gradient transition interface between zinc oxide and the resin, significantly reducing scattering loss, while greatly enhancing compatibility with the PUA matrix, providing dual guarantees for high transmittance and long-term stability.

[0045] Example 5 Example 5 Based on the preparation method of Example 1, 2g of TPO-L was replaced by 2g of benzoylformate, and the other conditions remained unchanged.

[0046] Example 6 Example 6 Based on the preparation method of Example 1, 0.3 g of fluorosilicone modified polyurethane acrylate was replaced with 0.3 g of a copolymer of 2-methyl methacrylate and butyl acrylate, and the other conditions remained unchanged.

[0047] Example 7 Example 7 Based on the preparation method of Example 1, 2g of TPO-L is replaced by 2g of benzoylformate, and 0.3g of fluorosilicone-modified polyurethane acrylate is replaced by 0.3g of a copolymer of 2-methyl methacrylate and butyl acrylate, while other conditions remain unchanged.

[0048] The optical diffusion films of Examples 5-7 were subjected to the above-mentioned performance tests, and the test results are shown in Table 4.

[0049] Table 4 Performance test table of Example 1 and Examples 5-7 project Example 1 Example 5 Example 6 Example 7 Transmittance / % 93.2 91.2 91.6 89.7 Longitudinal elongation at break / % 157 143 140 132 Transverse elongation at break / % 165 145 152 138 As shown in Table 4, a comparison of Example 1 and Examples 5-7 shows that the optical diffuser film of Example 1 outperforms the optical diffuser films of Examples 5-7. This may be because the benzoyl and phosphoryl radicals generated by the decomposition of TPO-L under UV irradiation are highly reactive and can directly undergo addition reactions with the acrylate double bonds in the fluorosilicone-modified polyurethane acrylate, initiating chain polymerization. This allows the distribution of the modified zinc oxide particles to be quickly "frozen" after the water-soluble UV-curable PUA resin is leveled, reducing the probability of aggregation due to solvent volatilization or molecular motion during the curing process, effectively improving the light transmittance of the optical diffuser film.

[0050] Examples 8-9 In Examples 8-9, based on the preparation method of Example 1, the thickness of the diffusion membrane was adjusted. The specific adjustments are shown in Table 5.

[0051] Comparative Examples 7-8 In Comparative Examples 7-8, based on the preparation method of Example 1, the thickness of the diffusion membrane was adjusted. The specific adjustments are shown in Table 5.

[0052] The optical diffusion films of Examples 8-9 and Comparative Examples 7-8 were subjected to the above-mentioned performance tests, and the test results are shown in Table 5.

[0053] Table 5 Thickness and performance test table of diffusion membrane of Example 1, Examples 8-9 and Comparative Examples 7-8 As shown in Table 5, comparing Example 1, Examples 8-9, and Comparative Examples 7-8, the optical diffuser film achieves optimal performance when the diffusion layer thickness is 8-12 μm, particularly when the diffusion layer thickness is 10 μm. This is likely because when the diffusion layer is too thin, the number of scattering particles is insufficient, resulting in uneven light diffusion, making it difficult to eliminate backlight hotspots and glare, and the coating has poor leveling, which can easily lead to defects. Furthermore, the film lacks mechanical strength and is prone to cracking and peeling under vehicle vibration. Excessive thickness results in a significant decrease in light transmittance, excessive haze, resulting in a whitish, blurry image, and insufficient curing, leading to internal stress accumulation in the coating, which can cause warping or cracking under temperature shock.

[0054] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An optical diffusion film for a vehicle display, characterized in that: The invention comprises a substrate layer and a diffusion layer, wherein the diffusion layer comprises the following components in parts by weight: 60-80 parts of water-soluble UV-curable PUA resin, 5-20 parts of modified zinc oxide particles, 1-3 parts of photoinitiator, 0.1-0.5 parts of leveling agent, and 20-40 parts of deionized water; the particle size of the zinc oxide nanoparticles is 1-3 μm; and the substrate layer comprises PMMA.

2. The optical diffusion film for a vehicle display according to claim 1, characterized in that: The preparation of the modified zinc oxide particles comprises the following steps: S1: A certain amount of zinc oxide particles was mixed with water to prepare a zinc oxide particle aqueous suspension with a mass concentration of 5.8%, potassium aluminum sulfate (1.8% by mass of the zinc oxide particles) was added, and the mixture was stirred at 3200 r / min for 1 hour. Ammonia water was added to adjust the pH of the suspension to 8.5, and the mixture was heated to 88°C and stirred at 150 r / min for 25 minutes. The mixture was then ultrasonically treated at 300W for 2 minutes, and ammonium persulfate (0.12% by mass of the suspension) was added. After stirring evenly, the mixture was kept warm at 50°C for 15 minutes, and then vacuum filtered and dried in a vacuum drying oven at 80°C to obtain activated zinc oxide particles. S2: Silane coupling agent KH-550 was added to distilled water and mixed, and then added to anhydrous ethanol to prepare a solution with a mass fraction of silane coupling agent KH-550 of 3.5%, wherein the volume ratio of distilled water to anhydrous ethanol was 1:

3. The solution was allowed to stand for 2 hours, and then the activated zinc oxide particles were added. The mixture was ultrasonically dispersed for 2 hours, and then the pH was adjusted to 3.5 with glacial acetic acid. The mixture was stirred at a speed of 1500 r / min for 2 hours, and then vacuum dried to obtain modified zinc oxide particles.

3. The optical diffusion film for a vehicle display according to claim 1, characterized in that: The photoinitiator is at least one of TPO-L and benzoylformate.

4. The optical diffusion film for a vehicle display according to claim 1, characterized in that: The photoinitiator is TPO-L.

5. The optical diffusion film for a vehicle display according to claim 1, characterized in that: The leveling agent is at least one of fluorosilicone modified polyurethane acrylate and a copolymer of 2-methyl methacrylate and butyl acrylate.

6. The optical diffusion film for a vehicle display according to claim 1, characterized in that: The leveling agent is fluorosilicone modified polyurethane acrylate.

7. The optical diffusion film for a vehicle display according to claim 1, characterized in that: The thickness of the diffusion layer is 12-20 μm.

8. The method for preparing an optical diffusion film for a vehicle display according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: Plasma-treating PMMA to obtain plasma-treated PMMA; S2: Weigh the formulated amount of water-soluble UV-curable PUA resin and mix it with deionized water. Stir at 800 rpm for 10 minutes to obtain a resin solution. Mix the modified zinc oxide particles with the resin solution. Then, add the formulated amount of photoinitiator and leveling agent and mix to obtain a suspension. S3: The suspension is coated on the plasma-treated PMMA, which is kept in the dark and cured by ultraviolet irradiation to obtain an optical diffusion film for a vehicle display.

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