An optical-grade transparent colored film and its preparation method

Abstract

This application discloses an optical-grade transparent colored film and its preparation method. The optical-grade transparent colored film includes a barrier layer, a color-developing layer, and a high-transparency layer. The raw materials for preparing the color-developing layer include optical polyester chips, color masterbatch, and vermifuge extract. This application adds vermifuge extract to the color-developing layer, which significantly improves the interfacial compatibility between the color masterbatch and the optical polyester chips. During melt blending, the vermifuge extract can be directionally anchored on the surface of the color masterbatch, forming a nanoscale uniform dispersion system. This effectively eliminates the microscopic aggregation defects caused by phase separation in traditional processes, thereby achieving high transparency and color stability of the optical film.

Description

Technical Field

[0001] This application relates to the field of thin films, specifically to an optical-grade transparent colored film and its preparation method. Background Technology

[0002] With the rapid development of display technology, high-end optical display devices such as Mini LED and OLED displays, flexible foldable screens, and automotive touch panels are placing increasingly stringent performance requirements on core optical film materials. Optical-grade polyester film, due to its excellent optical uniformity, high dimensional stability, and weather resistance, has become a core substrate for key optical components such as backlight modules, polarizers, and brightness enhancement films. Optical uniformity typically requires a transmittance exceeding 90%, posing extremely high challenges to the purity of the material itself and the processing technology. However, to achieve specific optical functions such as blue light reduction or color adjustment, and to meet aesthetic requirements, precise coloring of the polyester film is necessary. Traditional optical films have significant shortcomings in balancing high transmittance, low color difference, and long-term stability. Especially in complex optical design scenarios, even slight color shifts or performance degradation can directly lead to display color distortion and reduced device lifespan, making it difficult to meet the technical demands of cutting-edge fields such as 4K and 8K ultra-high-definition displays, AR, and VR.

[0003] Currently, polyester film coloring technologies are mainly divided into two categories: coating and additive methods. The coating method achieves coloring by applying a resin layer containing dye to the film surface, such as using acrylate or polyurethane as the coating material. While this method can preserve the optical properties of the substrate, it suffers from weak adhesion between the coating and the substrate interface, poor scratch resistance, and long-term use can lead to coating peeling, uneven color, and a color difference value (Delta E) potentially exceeding 3.0. Furthermore, the coating process requires extremely high film surface flatness, increasing processing costs and yield risks. In contrast, the additive method directly incorporates pigments or dyes into the polyester matrix for melt blending and achieves bulk coloring through extrusion molding. Its advantages lie in high color stability and strong process compatibility. However, the inorganic pigments used in traditional additive methods, such as titanium dioxide and carbon black, or the organic dyes, such as anthraquinone compounds, have insufficient affinity with the polyester molecular chain, leading to two major problems. First, uneven pigment dispersion causes local agglomeration, forming micron-sized scattering points, resulting in a significant decrease in light transmittance and an increase in haze, severely degrading optical performance. Secondly, the weak interfacial adhesion between the pigment and the substrate makes it prone to pigment migration under heat, humidity, and light conditions, resulting in discoloration or whitening on the film surface. Migrating pigment molecules accelerate photo-oxidative aging of the substrate, leading to a reduction in product lifespan of more than 30%.

[0004] While existing technologies attempt to improve dispersibility through surface modification, such as coating pigments with silane coupling agents or adding solvents like maleic anhydride grafts, they still struggle to completely solve the performance degradation problem at high additive levels. Furthermore, the introduced modifiers may trigger side reactions such as thermal degradation producing volatile substances, further limiting the application of optical films in high-end applications. Therefore, developing a polyester film preparation technology that combines high color stability, excellent optical performance, and long-term durability has become a critical challenge that urgently needs to be overcome in this field. Summary of the Invention

[0005] The purpose of this application is to provide an optical-grade transparent colored film with high transparency and good color stability.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: providing an optical-grade transparent colored film, including a barrier layer, a color developing layer and a high-transparency layer, wherein the raw materials for preparing the color developing layer include: optical polyester chips, color masterbatch and worm fork extract.

[0007] As a preferred option, the raw materials for preparing the color development layer also include pentaerythritol tetrastearic acid.

[0008] As another preferred embodiment, the raw materials for preparing the barrier layer include: optical polyester chips and a first masterbatch, wherein the first masterbatch has the function of blocking ultraviolet rays.

[0009] As another preferred embodiment, the first masterbatch is a complex of β-cyclodextrin and ferulic acid.

[0010] As another preferred method, the preparation method of the first masterbatch is as follows: dispersing the β-cyclodextrin in water to obtain solution A, dispersing the ferulic acid in a mixture of ethanol and water to obtain solution B, mixing solution A and solution B and stirring continuously, refrigerating the mixed solution, separating the precipitate, and drying to obtain the first masterbatch.

[0011] As another preferred option, the raw materials for preparing the high-permeability layer include: low-viscosity PETG, KH550 modified nano-silica, fluorinated ethylene copolymer, calcium stearate, and optical polyester chips.

[0012] This application also provides a method for preparing an optical-grade transparent colored film, comprising the following preparation steps: S1: preparing a first masterbatch composed of β-cyclodextrin and ferulic acid; blending and melt-extruding the first masterbatch with optical polyester chips to obtain a barrier layer; melting and extruding the optical polyester chips, color masterbatch, and worm fork extract to obtain a color developing layer; S2: mixing and granulating KH550 modified nano-silica, fluorinated polyethylene copolymer, calcium stearate, and PETG to obtain a second masterbatch; blending and melt-extruding the second masterbatch with an optical polyester film to obtain a high-transparency layer; S3: co-extruding the barrier layer, the color developing layer, and the high-transparency layer, casting and cooling, biaxially stretching, shaping, cooling, and winding to obtain the optical-grade transparent colored film.

[0013] Further preferably, step S1 may also include: preparing a first masterbatch of β-cyclodextrin and ferulic acid composite; blending and melt-extruding the first masterbatch with optical polyester chips to obtain a barrier layer; and melting and extruding the optical polyester chips, color masterbatch, vermifuge fork extract and pentaerythritol tetrastearic acid to obtain a color developing layer.

[0014] Further preferably, the preparation method of the first masterbatch is as follows: dispersing the β-cyclodextrin in water to obtain solution A, dispersing the ferulic acid in a mixture of ethanol and water to obtain solution B, mixing solution A and solution B and stirring continuously, refrigerating the mixed solution, separating the precipitate, and drying to obtain the first masterbatch.

[0015] Further preferred, the preparation steps include: S1: According to the mass fraction, 5% to 30% of the first masterbatch and the remainder of the optical polyester chips are blended and melt-extruded to obtain the barrier layer; according to the mass fraction, 100 to 150 parts by mass of the optical polyester chips, an appropriate amount of the color masterbatch, 1 to 3 parts by mass of the worm fork extract, and 1 to 5 parts by mass of the pentaerythritol tetrastearic acid are blended and melt-extruded to obtain the color developing layer; S2: According to the mass fraction, 5% to 15% of the KH550 modified nano silica, 1 S1: Mix 3% to 3% of the fluorinated polyethylene copolymer, 0.5% to 1% of the calcium stearate and the balance of the PETG and granulate to obtain the second masterbatch; S2: 5% to 10% of the second masterbatch and the balance of the optical polyester chips are blended and melt-extruded to obtain the high-transparency layer; S3: The barrier layer, the color-developing layer and the high-transparency layer are cast onto a cooling casting roll through a co-extrusion die to form a three-layer film casting sheet; the film casting sheet is preheated and biaxially stretched, and after heat setting and cooling and winding, the optical-grade transparent colored film is obtained.

[0016] Compared with the prior art, the beneficial effects of this application are as follows:

[0017] (1) In this application, worm fork extract is added to the color development layer, which significantly improves the interfacial compatibility between the color masterbatch and the optical polyester chips. During the melt blending process, the worm fork extract can be oriented and anchored on the surface of the color masterbatch to form a nanoscale uniform dispersion system, which effectively eliminates the micro-aggregation defects caused by phase separation in the traditional process.

[0018] (2) This application provides a barrier layer on the outside of the color development layer, which can effectively block or absorb ultraviolet rays, significantly slow down the photo-oxidative aging of the material, and the barrier layer can also effectively maintain the optical performance of the optical-grade film, avoid the light transmittance from decaying over time, maintain the high definition and smooth surface of the film for a long time, and extend the service life of display screens, touch screens and other devices.

[0019] (3) In this application, adding KH550 modified nano-silica to the high-transmittance layer can maintain high light transmittance while improving the mechanical properties of the membrane. Detailed Implementation

[0020] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0021] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0022] This application provides an optical-grade transparent colored film, which is a three-layer composite structure including a barrier layer, a color developing layer and a high-transparency layer. The raw materials for preparing the color developing layer include: optical polyester chips, color masterbatch and worm fork extract.

[0023] Verticillium extract is a product extracted from *Rhodotorula velutipes*, and its main component is polysaccharides, including galactomannan sulfate. The vast majority of red algae are multicellular, with a very small number being unicellular. Many red algae have significant economic value and are used in food, medicine, textiles, and other fields. Most red algae are marine, commonly found near tropical and subtropical coasts, and often attach to other plants.

[0024] This application adds worm fork extract to the color development layer, which significantly improves the interfacial compatibility between the masterbatch and the optical polyester chips. During the melt blending process, the worm fork extract can be oriented and anchored on the surface of the masterbatch to form a nanoscale uniform dispersion system, effectively eliminating the micro-aggregation defects caused by phase separation in traditional processes.

[0025] In addition, the addition of worm fork extract enables optical-grade transparent colored films to maintain their inherent light transmission advantage while exhibiting outstanding color uniformity and transparent texture in the color rendering dimension, providing high-end optical devices with innovative solutions that combine aesthetic value and functional precision.

[0026] The optical-grade transparent colored film of this application is a three-layer composite structure, including a barrier layer, a color developing layer and a high-transparency layer. The raw materials for preparing the barrier layer include optical polyester chips and a first masterbatch.

[0027] This application incorporates a barrier layer on the outer side of the color development layer, primarily to block ultraviolet (UV) radiation. UV radiation can cause polyester molecular chain breakage, yellowing, and embrittlement. The barrier layer effectively blocks or absorbs UV radiation, significantly slowing down the photo-oxidative aging of the material. Furthermore, the barrier layer effectively maintains the optical properties of the optical-grade film, preventing light transmittance from decreasing over time, thus preserving the film's high clarity and smooth surface over the long term, and extending the lifespan of devices such as displays and touchscreens.

[0028] In some embodiments of this application, the first masterbatch is a complex of β-cyclodextrin and ferulic acid. Ferulic acid can absorb UVA / UVB, while cyclodextrin forms cavities through its β-folded structure, which can physically reflect / scatter ultraviolet rays. The combination of the two achieves full-band protection. In addition, the inclusion of cyclodextrin can improve the stability of ferulic acid and reduce photolysis loss; at the same time, the antioxidant properties of ferulic acid can delay the oxidative degradation of cyclodextrin caused by UV, forming a two-way protection.

[0029] The optical-grade transparent colored film of this application has a three-layer composite structure, including a barrier layer, a color developing layer and a high-transparency layer. The raw materials for preparing the high-transparency layer include: low-viscosity PETG, KH550 modified nano-silica, fluorinated ethylene copolymer, calcium stearate and optical polyester chips.

[0030] When applying the optical-grade transparent colored film of this application, it is configured from the outside to the inside as a barrier layer, a color developing layer, and a high-transmittance layer. The high-transmittance layer is configured with high light transmittance to improve the light transmittance of the subsequent composite film. Adding KH550 modified nano-silica to the high-transmittance layer can maintain high light transmittance while improving the mechanical properties of the film.

[0031] The intrinsic viscosity of PETG is less than 1 dL / g.

[0032] In some preferred embodiments, the raw materials for preparing the colorimetric layer of this application also include pentaerythritol tetrastearic acid. Pentaerythritol tetrastearic acid has good thermal stability, lubricity, and biodegradability, and is widely used as a lubricant and surfactant.

[0033] Adding pentaerythritol tetrastearic acid to the color development layer can maintain good haze while further improving the light transmittance of the color development layer and effectively maintaining the color stability in the optical film.

[0034] This application also provides a method for preparing an optically grade transparent colored film, comprising the following preparation steps:

[0035] S1: Prepare the first masterbatch of β-cyclodextrin and ferulic acid composite, blend the first masterbatch with optical polyester chips and melt extrude to obtain the barrier layer; melt and extrude the optical polyester chips, color masterbatch, and worm fork extract to obtain the color development layer.

[0036] S2: KH550 modified nano-silica, fluorinated polyethylene copolymer, calcium stearate and PETG are mixed and granulated to obtain a second masterbatch. The second masterbatch is then blended and melt-extruded with an optical polyester film to obtain a high-permeability layer.

[0037] S3: The barrier layer, color layer and high transparency layer are co-extruded, cast and cooled, biaxially stretched, shaped, cooled and wound to obtain an optical-grade transparent colored film.

[0038] This application also provides a method for preparing a first masterbatch by combining β-cyclodextrin and ferulic acid: dispersing β-cyclodextrin in water to obtain solution A, dispersing ferulic acid in a mixture of ethanol and water to obtain solution B, mixing solution A and solution B and stirring continuously for 8 to 20 hours, adding 0.05 wt% hydroxypropyl methylcellulose to the mixed solution, refrigerating in a refrigerator below 8°C, separating and drying the precipitate to obtain the first masterbatch.

[0039] This application also provides a method for preparing KH550 modified nano-silica, comprising the following steps: drying nano-silica in an oven at 105°C for 2 hours; mixing KH550, deionized water, and ethanol in a mass ratio of 1:1:10; stirring at room temperature for 30 minutes to obtain a first solution; weighing 100g of n-butanol into a 250mL beaker, adding 5g of nano-silica, and stirring until completely impregnated; sonicating for 30 minutes to form a uniform dispersion; transferring the dispersion to a round-bottom flask, placing it in an oil bath and heating to 80°C; slowly adding the first solution dropwise; reacting at a constant temperature for 6 hours with stirring; after the reaction is complete, centrifuging, washing, and drying the product to obtain KH550 modified nano-silica.

[0040] In this application, pentaerythritol tetrastearic acid may also be added to the color development layer. The preparation method is adjusted accordingly to: mixing optical polyester chips, color masterbatch, worm fork extract and pentaerythritol tetrastearic acid and then melting and extruding them in a screw at 280°C to obtain the color development layer.

[0041] The color development layer of this application adds color masterbatch to make the overall optical film present color and have high transparency. The addition of color masterbatch is selected and added according to the actual color development requirements. However, the selection of color masterbatch may reduce the overall transparency of the optical film. Therefore, it is recommended to choose transparent pigments and reduce the amount of color masterbatch used to reduce the impact of color masterbatch on the transparency of the optical film.

[0042] The addition of vermifuge fork extract and pentaerythritol tetrastearic acid to the color development layer in this application can improve the dispersion of the masterbatch in the polyester and effectively stabilize the color, thereby improving the transparency of the optical film and stabilizing the color.

[0043] In some specific embodiments, the preparation method of this application is as follows:

[0044] S1: β-cyclodextrin is dispersed in water to prepare solution A, ferulic acid is dispersed in a mixture of ethanol and water to prepare solution B, solution A and solution B are mixed and stirred continuously, the mixed solution is refrigerated and the precipitate is separated, and the first masterbatch is obtained after drying.

[0045] 5%–30% of the first masterbatch and the remainder of optical polyester chips are blended and melt-extruded to obtain a barrier layer; 100–150 parts by weight of optical polyester chips, an appropriate amount of color masterbatch, 1–3 parts by weight of vermifuge fork extract, and 1–5 parts by weight of pentaerythritol tetrastearic acid are blended and melt-extruded to obtain a color developing layer.

[0046] S2: By mass percentage, 5%–15% KH550 modified nano-silica, 1%–3% fluorinated polyethylene copolymer, 0.5%–1% calcium stearate and the balance PETG are mixed and granulated to obtain the second masterbatch. 5%–10% of the second masterbatch and the balance optical polyester chips are blended and melt-extruded to obtain the high-permeability layer.

[0047] S3: The barrier layer, color development layer and high transparency layer are cast onto a cooling casting roll through a co-extrusion die to form a three-layer film casting sheet. The film casting sheet is preheated and biaxially stretched. After heat setting and cooling and winding, an optical-grade transparent colored film of this application is obtained.

[0048] Example 1

[0049] An optical-grade transparent colored film is provided, comprising a barrier layer, a color developing layer, and a high-transparency layer. The barrier layer is prepared from optical polyester chips and a first masterbatch. The color developing layer is prepared from optical polyester chips, a color masterbatch, and worm fork extract. The high-transparency layer is prepared from low-viscosity PETG, KH550 modified nano-silica, fluorinated ethylene copolymer, calcium stearate, and optical polyester chips.

[0050] A method for preparing an optically grade transparent colored film is also provided, comprising the following preparation steps:

[0051] S1: β-Cyclodextrin is dissolved in water to obtain solution A, and ferulic acid is dissolved in a mixed solvent of ethanol and water to obtain solution B. The mass ratio of β-cyclodextrin to ferulic acid is 8:1. Solutions A and B are mixed and stirred continuously for 16 hours. 0.05wt% hydroxypropyl methylcellulose is added, and the mixture is refrigerated at 4°C for 4 hours to separate and obtain the first masterbatch. 30% of the first masterbatch and the remaining optical polyester chips are mixed evenly and then melt-extruded in a screw at 280°C to obtain the barrier layer. 100 parts by mass of optical polyester chips, color masterbatch, and 2 parts by mass of worm fork extract are mixed and then melt-extruded in a screw at 280°C to obtain the color developing layer. The selection and amount of color masterbatch are adjusted according to actual needs.

[0052] S2: By mass percentage, 15% KH550 modified nano-silica, 2% fluorinated polyethylene copolymer, 0.5% calcium stearate and the balance PETG are mixed and granulated to obtain the second masterbatch, wherein the intrinsic viscosity of PETG is 0.5 dL / g. 5% of the second masterbatch and the balance optical polyester chips are mixed evenly and then melt-extruded in a screw at 280°C to obtain a high-permeability layer.

[0053] S3: The materials of the barrier layer, color layer and high transparency layer are co-extruded through a die and cast onto a cooling casting roller to form a three-layer film casting sheet. The film casting sheet is preheated and subjected to 3 times longitudinal stretching and 5 times transverse stretching. The biaxially stretched polyester film is heat-set at 220°C and finally cooled and wound up to obtain an optical-grade transparent colored film.

[0054] Example 2

[0055] An optical-grade transparent colored film is provided, comprising a barrier layer, a color developing layer, and a high-transparency layer. The raw materials for preparing the color developing layer are: optical polyester chips, color masterbatch, worm fork extract, and pentaerythritol tetrastearate. Other components are consistent with those of the optical-grade transparent colored film in Example 1.

[0056] In the preparation method of optical-grade transparent colored film, step S1 is as follows: 100-150 parts by weight of optical polyester chips and 10 parts by weight of arbutin are mixed evenly and then melt-extruded in a screw at 280°C to obtain a barrier layer; 100-150 parts by weight of optical polyester chips, color masterbatch, 2 parts by weight of vermifuge fork extract and 2 parts by weight of pentaerythritol tetrastearic acid are mixed and then melt-extruded in a screw at 280°C to obtain a colored layer. The selection and amount of color masterbatch are adjusted according to actual needs, and other preparation steps are consistent with the preparation steps in Example 1.

[0057] Example 3

[0058] In step S1, the amount of worm fork extract added was adjusted to 1 part by mass, and the amount of pentaerythritol tetrastearic acid added was adjusted to 2 parts by mass. Other preparation steps were consistent with the preparation steps in Example 1.

[0059] Comparative Example 1

[0060] The raw materials used to prepare the color development layer did not contain worm fork extract, and the other preparation steps were consistent with those in Example 1.

[0061] Comparative Example 2

[0062] The raw materials used to prepare the color development layer did not contain worm fork extract, and the other preparation steps were consistent with those in Example 2.

[0063] Comparative Example 3

[0064] The high-transparency layer was prepared using optical polyester chips as the raw material, and the other preparation steps were consistent with those in Example 2.

[0065] Performance testing

[0066] 1. Transmittance and haze determination: The transmittance and haze of the optical-grade transparent colored films prepared in each example and comparative example were determined according to the method of GB / T2410-2008 "Determination of transmittance and haze of transparent plastics".

[0067] 2. Color Stability Test: Color stability is assessed using a five-level rating system. After accelerated aging tests on an optical-grade transparent colored film within a 3m x 3m test area, digital imaging technology is used to analyze the percentage of color-changing areas. The rating is based on the percentage of abnormal areas relative to the total test substrate, precisely calculated using professional image processing software. This value directly reflects the material's resistance to photofading. Specific grading standards are as follows:

[0068] Grade A: Color instability in ≤1% of the test area;

[0069] Grade B: Local areas with color instability exceeding 1% and less than or equal to 3%;

[0070] Grade C: Surface area greater than 3% and less than or equal to 5% exhibits unstable color;

[0071] Grade D: Significant color instability is observed in areas where the percentage is greater than 5% and less than or equal to 7%.

[0072] Grade E: Severe color instability exists in more than 7% and less than or equal to 10% of the test area.

[0073] 3. Tensile strength: Tensile strength testing shall be conducted in accordance with ASTM D-882 standard.

[0074] The colored films prepared in each embodiment and each comparative example were subjected to the above performance tests, and the test results are recorded in Table 1 below.

[0075] Table 1 Performance test results of each embodiment and comparative example

[0076] project Light transmittance (%) Haze (%) Color stability Tensile strength (MPa) Example 1 92.4 0.67 A 60.1 Example 2 95.6 0.65 A 58.4 Example 3 91.9 0.73 A 63.9 Comparative Example 1 84.7 0.94 D 56.7 Comparative Example 2 81.1 0.88 D 60.8 Comparative Example 3 78.2 1.21 C 32.5

[0077] Analyzing the performance test results in Table 1, the optical-grade transparent colored film prepared in this application exhibits superior transmittance, haze, color stability, and tensile strength compared to the optical film prepared in the comparative example. The optical film prepared in this application achieves high transmittance and tensile strength, low haze, and maintains color stability, making it suitable for numerous fields including displays and electronics, photovoltaics and new energy, building and energy conservation, the automotive industry, and optical instruments and photography.

[0078] Adding pentaerythritol tetrastearic acid to the colorimetric layer containing worm fork extract can improve the light transmittance of the optical film while maintaining its low haze, resulting in a brighter optical film. The tensile strength of the optical film slightly decreases after adding pentaerythritol tetrastearic acid.

[0079] By analyzing and comparing the performance test results of Example 2 and Comparative Example 3, this application can significantly improve the light transmittance by designing a high-transmittance layer, and at the same time improve the mechanical properties of the optical film by using KH550 modified nano-silica in the high-transmittance layer.

[0080] The optical-grade transparent colored film of this application can achieve high light transmittance and maintain color stability, and can be applied in high-end optical display devices to meet the needs of ultra-high-definition cutting-edge technology.

[0081] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an optical-grade transparent colored film, characterized in that, The preparation steps include the following: S1: According to the mass fraction, 5%~30% of the first masterbatch and the remainder of optical polyester chips are blended and melt-extruded to obtain the barrier layer; according to the mass fraction, 100~150 parts of optical polyester chips, an appropriate amount of color masterbatch, 1~3 parts of worm fork extract and 1~5 parts of pentaerythritol tetrastearic acid are blended and melt-extruded to obtain the color development layer. The preparation method of the first masterbatch is as follows: β-cyclodextrin is dispersed in water to prepare solution A, ferulic acid is dispersed in a mixture of ethanol and water to prepare solution B, solution A and solution B are mixed and stirred continuously for 8 to 20 hours, 0.05 wt% hydroxypropyl methylcellulose is added to the mixed solution, and the mixture is refrigerated in a refrigerator below 8 °C. The precipitate is separated and dried to obtain the first masterbatch. S2: Mix 5%~15% KH550 modified nano-silica, 1%~3% fluorinated polyethylene copolymer, 0.5%~1% calcium stearate and the balance PETG by mass fraction and granulate to obtain the second masterbatch; blend 5%~10% of the second masterbatch and the balance optical polyester chips by melt extrusion to obtain a high-permeability layer; The preparation method of the KH550 modified nano-silica is as follows: Nano-silica is dried in an oven at 105 ℃ for 2 hours. KH550, deionized water, and ethanol are mixed in a mass ratio of 1:1:10 and stirred at room temperature for 30 minutes to obtain a first solution. 100 g of n-butanol is weighed into a 250 mL beaker, and 5 g of the nano-silica is added and stirred until completely impregnated. The mixture is then sonicated for 30 minutes to form a uniform dispersion. The dispersion is transferred to a round-bottom flask, placed in an oil bath, and heated to 80 ℃. The first solution is slowly added dropwise, and the mixture is reacted at a constant temperature for 6 hours with stirring. After the reaction, the product is centrifuged, washed, and dried to obtain the KH550 modified nano-silica. S3: The barrier layer, the color-developing layer and the high-transparency layer are cast onto a cooling casting roll through a co-extrusion die to form a three-layer film casting sheet. The film casting sheet is preheated and biaxially stretched. After heat setting, cooling and winding, the optical-grade transparent colored film is obtained.

2. An optical-grade transparent colored film, characterized in that, It is prepared using the preparation method described in claim 1.