Optical-grade transparent colored film and preparation method thereof

Abstract

The invention discloses an optical-grade transparent colored film and a preparation method thereof, the optical-grade transparent colored film comprises a barrier layer, a color development layer and a high-transmittance layer, and the preparation raw materials of the color development layer comprise optical polyester chips, color master batches and a helminthosporium extract. According to the invention, the wormlike extract is added into the color developing layer, so that the interfacial compatibility between the color master batch and the optical polyester chip is remarkably improved, and the wormlike extract can be directionally anchored on the surface of the color master batch in the melt blending process to form a nano-scale uniform dispersion system; the microscopic aggregation defect caused by phase separation in the traditional process is effectively overcome, so that higher transparency and color stability of the optical film are realized.

Description

Technical Field

[0001] The present application relates to the field of thin films, and particularly to an optically transparent colored film and a preparation method thereof. Background Art

[0002] With the rapid development of display technologies, high-end optical display devices such as Mini LED and OLED display screens, flexible folding screens, and in-vehicle touch panels have increasingly stringent requirements for the performance of core optical film materials. Optically grade polyester films have become the core substrates for key optical components such as backlight modules, polarizers, and brightness enhancement films due to their excellent optical uniformity, high dimensional stability, and weather resistance. Optical uniformity generally requires a light transmittance exceeding ninety percent, which poses extremely high challenges to the purity of the material itself and the processing technology. However, in order to achieve specific optical functions such as anti-blue light or color adjustment, and to meet the appearance requirements, precise coloring treatment of polyester films is required. Traditional optical films have significant deficiencies in balancing high light transmittance, low color difference, and long-term stability. Especially in complex optical design scenarios, subtle chromaticity shifts or performance decays will directly lead to color distortion in displays and a decrease in the device lifespan, making it difficult to meet the technical requirements 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 methods and addition methods. The coating method achieves coloring by coating a resin layer containing dyes on the film surface. For example, acrylate or polyurethane is used as the coating material. Although this method can retain the optical properties of the substrate itself, there are problems such as weak adhesion at the interface between the coating and the substrate and poor scratch resistance. After long-term use, problems such as coating peeling and uneven chromaticity are likely to occur, and the color difference value Delta E may exceed 3.0. In addition, the coating process has extremely high requirements for the surface flatness of the film, increasing the processing cost and the risk of yield. In contrast, the addition 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 such as titanium dioxide and carbon black, or organic dyes such as anthraquinone compounds used in traditional addition methods have insufficient affinity with the polyester molecular chain, resulting in two major core problems. First, uneven dispersion of pigments leads to local agglomeration, forming micron-scale scattering points, which significantly reduces the light transmittance and increases the haze, seriously deteriorating the optical performance. Second, the binding force at the interface between the pigment and the substrate is weak, and pigment migration is likely to occur under thermal, humid, and light conditions, manifested as color spots or whitening on the film surface. The migrated pigment molecules will accelerate the photo-oxidative aging of the substrate, resulting in a product lifespan reduction of more than thirty percent.

[0004] Although the prior art has tried to improve the dispersibility by surface modification such as coating pigments with silane coupling agents or adding compatibilizers such as maleic anhydride grafted products, it is still difficult to completely solve the problem of performance attenuation at high addition amounts, and the introduced modifiers may cause side reactions such as thermal degradation to produce volatile substances, further restricting the application of optical films in high-end scenarios. Therefore, developing a polyester film preparation technology with high coloring stability, excellent optical properties and long-term durability has become a key problem that urgently needs to be solved in this field. Summary of the Invention

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

[0006] To achieve the above purpose, the technical solution adopted in this application is: to provide an optically transparent colored film, including a barrier layer, a color display layer and a high-transparency layer, wherein the preparation raw materials of the color display layer include: optical polyester chips, masterbatch and wormwood extract.

[0007] As a preference, the preparation raw materials of the color display layer further include pentaerythritol tetrastearate.

[0008] As another preference, the preparation raw materials of the barrier layer include: optical polyester chips and a first masterbatch, and the first masterbatch has the function of blocking ultraviolet rays.

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

[0010] As another preference, the preparation method of the first masterbatch is: 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 continuously stirring, refrigerating the mixed solution and separating the precipitate, and drying to obtain the first masterbatch.

[0011] As another preference, the preparation raw materials of the high-transparency layer include: low-viscosity PETG, KH550-modified nano-silica, ethylene fluoride copolymer, calcium stearate and optical polyester chips.

[0012] The present application also provides a method for preparing an optically transparent colored film, comprising the following preparation steps: S1: Prepare a first masterbatch of β-cyclodextrin and ferulic acid, and co-melt and extrude the first masterbatch with an optically polyester chip to obtain a barrier layer; melt and extrude the optically polyester chip, a color masterbatch, and a worm fork extract to obtain a color display layer; S2: Mix KH550-modified nano-silica, a fluorinated polyethylene copolymer, calcium stearate, and PETG to granulate and obtain a second masterbatch, and co-melt and extrude the second masterbatch with an optically polyester film to obtain a high-transparency layer; S3: Co-extrude the barrier layer, the color display layer, and the high-transparency layer, cast and cool, perform biaxial stretching, shape, cool, and wind up to obtain the optically transparent colored film.

[0013] Further preferably, the step S1 may also be: Prepare a first masterbatch of β-cyclodextrin and ferulic acid, and co-melt and extrude the first masterbatch with an optically polyester chip to obtain a barrier layer; melt and extrude the optically polyester chip, a color masterbatch, a worm fork extract, and pentaerythritol tetrastearate to obtain a color display layer.

[0014] Further preferably, the method for preparing the first masterbatch is: Disperse the β-cyclodextrin in water to obtain solution A, disperse the ferulic acid in a mixture of ethanol and water to obtain solution B, mix solution A and solution B and continuously stir, refrigerate the mixed solution and separate the precipitate, and dry to obtain the first masterbatch.

[0015] Further preferably, it comprises the following preparation steps: S1: According to mass fraction, co-melt and extrude 5% - 30% of the first masterbatch and the balance of the optically polyester chip to obtain the barrier layer; according to parts by mass, co-melt and extrude 100 - 150 parts by mass of the optically polyester chip, an appropriate amount of the color masterbatch, 1 - 3 parts by mass of the worm fork extract, and 1 - 5 parts by mass of pentaerythritol tetrastearate to obtain the color display layer; S2: According to mass fraction, mix 5% - 15% of the KH550-modified nano-silica, 1% - 3% of the fluorinated polyethylene copolymer, 0.5% - 1% of calcium stearate, and the balance of PETG to granulate and obtain the second masterbatch; co-melt and extrude 5% - 10% of the second masterbatch and the balance of the optically polyester chip to obtain the high-transparency layer; S3: Pass the barrier layer, the color display layer, and the high-transparency layer through a co-extrusion die head, cast them onto a cooling casting roller to form a film casting with a three-layer structure, preheat and perform biaxial stretching on the film casting, and after heat setting, cooling, and winding up, obtain the optically transparent colored film.

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

[0017] (1) In this application, worm fork extract is added to the color display layer, significantly improving the interfacial compatibility between the color masterbatch and the optical polyester chips. During the melt blending process, the worm fork extract can be directionally anchored on the surface of the color masterbatch, forming a nanoscale uniform dispersion system, effectively eliminating the microscopic aggregation defects caused by phase separation in the traditional process;

[0018] (2) A barrier layer is provided outside the color display layer in this application, which can effectively block or absorb ultraviolet rays, significantly slowing down the photo-oxidative aging of the material. The barrier layer can also effectively maintain the optical properties of the optical film, prevent the light transmittance from decaying over time, and long-term maintain the high clarity and smooth surface of the film, extending the service life of devices such as display screens and touch screens;

[0019] (3) Adding KH550-modified nano-silica to the high-transparency layer in this application can maintain high light transmittance while improving the mechanical properties of the film. Detailed implementation manners

[0020] Next, in combination with the specific implementation manners, this application will be further described. It should be noted that, on the premise of no conflict, the following-described embodiments or technical features can be arbitrarily combined to form new embodiments.

[0021] The terms "include" and "have" in the specification and claims of this application and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

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

[0023] The worm fork extract is a product extracted from the red alga worm fork. Its main component is polysaccharide, including sulfated galactan, etc. The vast majority of red algae are multicellular, and very few are unicellular algae. Many red algae have important economic values and are applied in fields such as food, medicine, and textiles. Most red algae are marine, commonly found near tropical and subtropical coasts, and often attached to other plants.

[0024] In this application, worm fork extract is added to the color display layer, significantly improving the interfacial compatibility between the color masterbatch and the optical polyester chips. During the melt blending process, the worm fork extract can be directionally anchored on the surface of the color masterbatch, forming a nanoscale uniform dispersion system, effectively eliminating the microscopic aggregation defects caused by phase separation in the traditional process.

[0025] In addition, adding worm fork extract enables the optical-grade transparent colored film to break through and exhibit excellent color uniformity and transparent texture in the color display dimension while maintaining its inherent light transmission advantage, providing an innovative solution with both aesthetic value and functional precision for high-end optical devices.

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

[0027] In the present application, a barrier layer is provided outside the color display layer, and its main purpose is to block ultraviolet rays. Ultraviolet rays can cause the polyester molecular chain to break, turn yellow, and become brittle. Setting up the barrier layer can effectively block or absorb ultraviolet rays, significantly slowing down the photo-oxidative aging of the material. The barrier layer can also effectively maintain the optical properties of the optical-grade film, prevent the light transmittance from decaying over time, maintain the high clarity and smooth surface of the film in the long term, and extend the service life of devices such as display screens and touch screens.

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

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

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

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

[0032] In some preferred embodiments of the present application, the raw materials for preparing the color display layer of the present application further include pentaerythritol tetrastearate. Pentaerythritol tetrastearate has good thermal stability, lubricity, and biodegradability, and is widely used as a lubricant and surfactant.

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

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

[0035] S1: Prepare the first masterbatch by compounding β-cyclodextrin and ferulic acid. Blending and melt-extruding the first masterbatch with optical polyester chips to obtain a barrier layer; melting and extruding optical polyester chips, color masterbatch, and worm fork extract to obtain a color display layer;

[0036] S2: Mix KH550-modified nano-silica, fluorinated polyethylene copolymer, calcium stearate, and PETG to granulate and obtain the second masterbatch. Blending and melt-extruding the second masterbatch with an optical polyester film to obtain a high-transparency layer;

[0037] S3: Co-extrude the barrier layer, color display layer, and high-transparency layer, cast and cool, perform biaxial stretching and then shape and cool and wind up to obtain an optical grade transparent colored film.

[0038] This application also provides a method for preparing the first masterbatch by compounding β-cyclodextrin and ferulic acid: Disperse β-cyclodextrin in water to obtain solution A, disperse ferulic acid in a mixture of ethanol and water to obtain solution B, mix solution A and solution B and continuously stir for 8 - 20 hours, add 0.05w.t% hydroxypropyl methylcellulose to the mixed solution, place it in a refrigerator below 8°C for refrigeration, separate and dry the precipitated product to obtain the first masterbatch.

[0039] This application also provides a method for preparing KH550-modified nano-silica, according to the following preparation steps: Place nano-silica in an oven at 105°C and dry for 2 hours. Mix KH550, deionized water, and ethanol in a ratio of 1:1:10, stir at room temperature for 30 minutes to obtain the first solution; weigh 100g of n-butanol in a 250mL beaker, add 5g of nano-silica and stir until it is completely wetted, sonicate for 30 minutes to form a homogeneous dispersion; transfer the dispersion to a round-bottom flask, place it in an oil bath and heat to 80°C, slowly dropwise add the first solution, react at a constant temperature with stirring for 6 hours, after the reaction, centrifuge, wash, and dry the product to obtain KH550-modified nano-silica.

[0040] In the color display layer of this application, pentaerythritol tetrastearate can also be added. Correspondingly, the preparation method is adjusted to: Mix optical polyester chips, color masterbatch, worm fork extract, and pentaerythritol tetrastearate and melt-extrude at 280°C in a screw rod to obtain a color display layer.

[0041] The color display layer of the present application makes the overall optical film present a color and have a high transparency by adding color masterbatch. The addition of the color masterbatch is selected and added according to actual color display requirements. However, the selection of the color masterbatch may cause a reduction in the overall transparency of the optical film. Therefore, it is recommended to select transparent pigments when choosing the color masterbatch and reduce the amount of the color masterbatch to reduce the impact of the color masterbatch on the transparency of the optical film.

[0042] The present application adds worm fork extract and pentaerythritol tetrastearate to the color display layer, which can improve the dispersion degree of the color masterbatch in polyester and effectively stabilize the color, so that the transparency of the optical film is improved and the color is stable.

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

[0044] S1: β-cyclodextrin is dispersed in water to obtain solution A, ferulic acid is dispersed in a mixture of ethanol and water to obtain solution B, solution A and solution B are mixed and continuously stirred, 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 remaining optical polyester chips are melt-blended and extruded to obtain a barrier layer; 100 - 150 parts by mass of optical polyester chips, an appropriate amount of color masterbatch, 1 - 3 parts by mass of worm fork extract, and 1 - 5 parts by mass of pentaerythritol tetrastearate are melt-blended and extruded to obtain a color display layer;

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

[0047] S3: The barrier layer, the color display layer and the high-transparency layer pass through a co-extrusion die head and are cast onto a cooling casting roller to form a film casting with a three-layer structure. The film casting is preheated and biaxially stretched, and after heat setting and cooling and winding, an optical-grade transparent colored film of the present application is obtained.

[0048] Example 1

[0049] An optical-grade transparent colored film is provided, including a barrier layer, a color display layer and a high-transparency layer. The preparation raw materials of the barrier layer are: optical polyester chips, the first masterbatch; the preparation raw materials of the color display layer are: optical polyester chips, color masterbatch, worm fork extract; the preparation raw materials of the high-transparency layer are: low-viscosity PETG, KH550-modified nano-silica, fluorinated ethylene copolymer, calcium stearate and optical polyester chips.

[0050] A preparation method of an optical-grade transparent colored film is also provided, including the following preparation steps:

[0051] S1: Dissolve β-cyclodextrin in water to obtain solution A, and dissolve ferulic acid in a mixed solvent of ethanol and water to obtain solution B. The mass ratio of β-cyclodextrin to ferulic acid is 8:1. Mix solution A and solution B and stir continuously for 16 hours. Add 0.05 w.t% hydroxypropyl methylcellulose, place it in a refrigerator at 4°C for 4 hours, and separate to obtain the first masterbatch. Mix 30% of the first masterbatch and the remaining optical polyester chips evenly, and melt and extrude them at 280°C in a screw to obtain a barrier layer; mix 100 parts by mass of optical polyester chips, color masterbatch, and 2 parts by mass of worm fork extract, and melt and extrude them at 280°C in a screw to obtain a color display layer, where the selection and addition amount of the color masterbatch are adjusted according to actual needs;

[0052] S2: Mix 15% KH550-modified nano-silica, 2% fluorinated polyethylene copolymer, 0.5% calcium stearate, and the remaining PETG by mass percentage to granulate and obtain the second masterbatch, where the intrinsic viscosity of PETG is 0.5 dL / g. Mix 5% of the second masterbatch and the remaining optical polyester chips evenly, and melt and extrude them at 280°C in a screw to obtain a high-transparency layer;

[0053] S3: Pass the materials of the barrier layer, color display layer, and high-transparency layer through a co-extrusion die head, and cast them onto a cooling casting roller to form a film casting with a three-layer structure. Preheat the film casting, perform 3 times longitudinal stretching and 5 times transverse stretching. Thermally set the biaxially stretched polyester film at 220°C, and finally wind it up through cooling to obtain an optical-grade transparent colored film.

[0054] Example 2

[0055] Provide an optical-grade transparent colored film, including a barrier layer, a color display layer, and a high-transparency layer. The raw materials for preparing the color display layer are: optical polyester chips, color masterbatch, worm fork extract, and pentaerythritol tetrastearate, and the other components are the same as those of the optical-grade transparent colored film in Example 1.

[0056] In the preparation method of the optical-grade transparent colored film, step S1 is: Mix 100 - 150 parts by mass of optical polyester chips and 10 parts by mass of arbutin evenly, and melt and extrude them at 280°C in a screw to obtain a barrier layer; mix 100 - 150 parts by mass of optical polyester chips, color masterbatch, 2 parts by mass of worm fork extract, and 2 parts by mass of pentaerythritol tetrastearate, and melt and extrude them at 280°C in a screw to obtain a color display layer, where the selection and addition amount of the color masterbatch are adjusted according to actual needs, and the other preparation steps are the same as those in Example 1.

[0057] Example 3

[0058] In step S1, the addition amount of the vermifork extract is adjusted to 1 part by mass, and the addition amount of pentaerythritol tetrastearate is adjusted to 2 parts by mass. Other preparation steps are the same as those in Example 1.

[0059] Comparative Example 1

[0060] The raw materials for preparing the color display layer do not contain the vermifork extract, and other preparation steps are the same as those in Example 1.

[0061] Comparative Example 2

[0062] The raw materials for preparing the color display layer do not contain the vermifork extract, and other preparation steps are the same as those in Example 2.

[0063] Comparative Example 3

[0064] The raw materials for preparing the high-transparency layer are optical polyester chips, and other preparation steps are the same as those in Example 2.

[0065] Performance Testing

[0066] 1. Measurement of light transmittance and haze: The light transmittance and haze of the optically transparent colored films prepared in each example and each comparative example were measured according to the method of GB / T 2410-2008 "Determination of Light Transmittance and Haze of Transparent Plastics".

[0067] 2. Color stability test: The color stability adopts a five-level evaluation system. After accelerating the aging test of the optically transparent colored film in a 3m×3m test area, the proportion of the color change area is analyzed by digital imaging technology. The evaluation basis is the percentage of the abnormal area in the total test substrate accurately measured by professional image processing software, and this value directly reflects the performance of the material in resisting photobleaching. The specific grading standards are as follows:

[0068] Grade A: The color of ≤1% of the test area is unstable;

[0069] Grade B: Color instability appears in local areas greater than 1% and less than or equal to 3%;

[0070] Grade C: Color instability appears on the surface area greater than 3% and less than or equal to 5%;

[0071] Grade D: Obvious color instability appears in areas greater than 5% and less than or equal to 7%;

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

[0073] 3. Tensile strength: The tensile strength test refers to the ASTM D-882 standard test.

[0074] The above performance tests were carried out on the colored films prepared in each example and each comparative example, and the test results were recorded in Table 1 below.

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

[0076] Analyzing the performance test results in Table 1, the light transmittance, haze, color stability and tensile strength of the optically transparent colored film prepared in this application are all superior to those of the optical film prepared in the comparative example. The optical film prepared in this application can achieve high light transmittance and tensile strength, low haze, and can also maintain the color stability of the film, and can be applied to many fields such as display and electronics, photovoltaics and new energy, architecture and energy conservation, automotive industry, optical instruments and photography.

[0077] Further adding pentaerythritol tetrastearate to the color-developing layer containing worm fork extract can improve the light transmittance of the optical film on the premise of maintaining the low haze of the optical film, and obtain a more transparent optical film. The tensile strength of the optical film decreases slightly after adding pentaerythritol tetrastearate.

[0078] Analyzing the comparison of the performance test results of Example 2 and Comparative Example 3, by designing a high-transparency layer in this application, the light transmittance can be significantly improved, and the mechanical properties of the optical film are also improved by KH550-modified nano-silica in the high-transparency layer.

[0079] The optically transparent colored film of this application can achieve high light transmittance and maintain color stability, and can be applied to high-end optical display devices to meet the requirements of ultra-high definition cutting-edge technologies.

[0080] The basic principles, main features and advantages of this application have been described above. Those skilled in the art of this industry should understand that this application is not limited by the above embodiments. What is described in the above embodiments and the specification is only the principle of this application. Without departing from the spirit and scope of this application, this application will have various changes and improvements, and these changes and improvements all fall within the scope of this application claimed. The scope of protection required by this application is defined by the appended claims and their equivalents.

Claims

1. An optical-grade transparent colored film, characterized in that, It includes a barrier layer, a color display layer and a high-transparency layer. The raw materials for preparing the color display layer include: optical polyester chips, masterbatch and extract of worm fork.

2. The optical grade transparent colored film according to claim 1, characterized in that The raw materials for preparing the color display layer further include pentaerythritol tetrastearate.

3. The optical grade transparent colored film according to claim 1, characterized in that, The raw materials for preparing the barrier layer include: optical polyester chips and a first masterbatch, and the first masterbatch has the function of blocking ultraviolet rays.

4. The optical grade transparent colored film according to claim 3, characterized in that, The first masterbatch is a complex of β-cyclodextrin and ferulic acid.

5. The optically transparent colored film according to claim 4, wherein, The preparation method of the first masterbatch is: 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 continuously stirring, refrigerating the mixed solution and separating the precipitate, and drying to obtain the first masterbatch.

6. The optically transparent colored film according to claim 1, wherein The raw materials for preparing the high-transparency layer include: low-viscosity PETG, KH550-modified nano-silica, ethylene-vinyl fluoride copolymer, calcium stearate and optical polyester chips.

7. A method for preparing an optically transparent colored film, characterized in that, It includes the following preparation steps: S1: Prepare the first masterbatch of β-cyclodextrin and ferulic acid complex, and co-melt and extrude the first masterbatch with optical polyester chips to obtain the barrier layer; melt and extrude optical polyester chips, masterbatch and extract of worm fork to obtain the color display layer; S2: Mix KH550-modified nano-silica, ethylene-vinyl fluoride copolymer, calcium stearate and PETG to granulate to obtain the second masterbatch, and co-melt and extrude the second masterbatch with optical polyester film to obtain the high-transparency layer; S3: Co-extrude the barrier layer, the color display layer and the high-transparency layer, cast and cool, and carry out biaxial stretching, then shape, cool and wind up to obtain the optical-grade transparent colored film.

8. The preparation method according to claim 7, characterized in that, The S1 step can also be: prepare the first masterbatch of β-cyclodextrin and ferulic acid complex, and co-melt and extrude the first masterbatch with optical polyester chips to obtain the barrier layer; melt and extrude optical polyester chips, masterbatch, extract of worm fork and pentaerythritol tetrastearate to obtain the color display layer.

9. The preparation method according to claim 8, characterized in that, The preparation method of the first masterbatch is: 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 continuously stirring, refrigerating the mixed solution and separating the precipitate, and drying to obtain the first masterbatch.

10. The preparation method according to claim 8, characterized in that, It includes the following preparation steps: S1: According to mass fraction, co-melt and extrude 5% - 30% of the first masterbatch and the remaining optical polyester chips to obtain the barrier layer; according to mass parts, co-melt and extrude 100 - 150 mass parts of the optical polyester chips, an appropriate amount of masterbatch, 1 - 3 mass parts of the extract of worm fork, and 1 - 5 mass parts of pentaerythritol tetrastearate to obtain the color display layer; S2: According to mass fraction, mix 5% - 15% of the KH550-modified nano-silica, 1% - 3% of the ethylene-vinyl fluoride copolymer, 0.5% - 1% of calcium stearate and the remaining PETG to granulate to obtain the second masterbatch; co-melt and extrude 5% - 10% of the second masterbatch and the remaining optical polyester chips to obtain the high-transparency layer; S3: Pass the barrier layer, the color display layer and the high-transparency layer through a coextrusion die head and cast them onto a cooling casting roller to form a film casting with a three-layer structure. Preheat and biaxially stretch the film casting, and after heat setting and cooling and winding, obtain the optical-grade transparent colored film.