A photochromic cellulose ester film, its preparation method and application

Abstract

This invention discloses a photochromic cellulose ester film. The raw materials for preparation include at least: a color-changing powder, a polyol ester plasticizer, and a cellulose ester. The polyol ester plasticizer has the following general structural formula: B-(G-A)n-G-B, where B is a benzene monocarboxylic acid residue, G is an alkylene diol residue with 2-12 carbon atoms or an oxoalkylene diol residue with 4-12 carbon atoms, and A is an alkylene dicarboxylic acid residue with 4-12 carbon atoms. This invention uses a polyol ester plasticizer with a special structure and a color-changing powder to prepare a photochromic cellulose ester film. The polyol ester plasticizer has good compatibility in the photochromic cellulose ester film system, resulting in a photochromic cellulose ester film with a high appearance and excellent optical properties. The prepared photochromic cellulose ester film exhibits ring-opening color change and ring-closed fading, optimizing the color-changing spatial properties and giving the photochromic cellulose ester film excellent plasticizing properties, as well as excellent water-blocking and retention effects.

Description

Technical Field

[0001] This invention relates to the field of polymer compound compositions, and more specifically to a photochromic cellulose ester film, its preparation method, and its application. Background Technology

[0002] Cellulose ester films possess excellent optical properties and are easy to process, making them widely used in the manufacturing of sunglasses and polarized lenses. With the improvement of people's living standards, photochromic polarized lenses are becoming increasingly popular. However, existing polarized lenses have a narrow color-changing range, failing to achieve optimal light-blocking effects. Furthermore, existing cellulose ester films are prone to water absorption and reaction, leading to accelerated degradation and impacting lens lifespan. Therefore, developing a photochromic cellulose ester film with excellent color-changing effects, long lifespan, and good appearance is crucial.

[0003] Chinese invention patent CN115093592B discloses a photochromic anti-counterfeiting card film and its preparation method. The method involves preheating and vitrifying a PC film, then hot-pressing a BOPET film onto one side of the PC film coated with a photochromic transfer liquid. After cooling, the BOPET film is peeled off to obtain the photochromic anti-counterfeiting card PC film. The prepared photochromic anti-counterfeiting card film is not easily peeled off, has good anti-counterfeiting properties, and is not easily tampered with. However, uneven coating thickness is prone to occur, leading to color differences and poor product durability. Chinese invention patent CN103534308B discloses a photochromic film and its manufacturing method. A non-solvent-based composition is coated into a photochromic film, which is easy to control in terms of film thickness and can be made into a larger area. However, because the photochromic dye particles are compressed within the coating, the dye particles attract each other after color change, preventing rapid color conversion. Summary of the Invention

[0004] To develop a photochromic cellulose ester film with excellent color-changing effect, long service life and good appearance, the first aspect of the present invention provides a photochromic cellulose ester film, the raw materials for which include at least: color-changing powder, polyol ester plasticizer, and cellulose ester, wherein the general structural formula of the polyol ester plasticizer is as follows: B-(GA)nGB, where: B is a benzene monocarboxylic acid residue, G is an alkylene diol residue with 2-12 carbon atoms or an oxoalkylene diol residue with 4-12 carbon atoms, A is an alkylene dicarboxylic acid residue with 4-12 carbon atoms, and n is an integer ≥0.

[0005] During the experiment, the inventors discovered that the photochromic cellulose ester film prepared using polyol ester plasticizer and color-changing powder had a better appearance and excellent optical properties. They speculated that the possible reason was that the polyol ester plasticizer and cellulose have similar structures. The polyol ester plasticizer formed by the esterification of hydroxyl groups in the polyol has a similar structure to the hydroxyl groups in cellulose. Therefore, the polyol ester plasticizer and cellulose have good compatibility, and the resulting photochromic cellulose ester film system is uniform and stable, with a good surface appearance and excellent optical properties.

[0006] The inventors discovered during experiments that using polyol ester plasticizers with terminal benzene monocarboxylic acid residues and intermediate alkylene glycol residues (2-12 carbon atoms) or oxoalkylene glycol residues (4-12 carbon atoms) resulted in photochromic cellulose ester films exhibiting ring-opening color change and ring-closing fading, with a large color-changing space. This gave the photochromic cellulose ester films excellent plasticizing properties, as well as excellent water-blocking and retention effects. The likely reason for this is that the larger molecular structure of the polyol ester plasticizer increases the spatial properties of the photochromic cellulose ester film. The increased spatial structure and higher boiling point inhibit plasticizer precipitation, resulting in excellent retention. Compared to traditional plasticizers that are prone to precipitation, the appearance of the photochromic cellulose ester film is further improved.

[0007] Compared to phosphate esters and phthalate esters, the polyol ester plasticizer used in this invention exhibits superior retention and durability. Phosphate ester plasticizers, due to their low polarity in solvent-evaporating film-forming systems, are easily extracted with the solvent, resulting in a small actual residual amount. This reduces the plasticity and space of the final film, severely affecting the color-changing and fading effects of the photochromic cellulose ester film. Increasing the amount of phosphate ester plasticizer leads to poor cellulose dissolution, causing precipitation problems that severely affect the product appearance. After absorbing water, the phosphate ester in the cellulose ester film prepared with phosphate ester plasticizer readily reacts with water, accelerating the degradation of the cellulose ester film, causing acetic acid syndrome, and significantly reducing the service life of the cellulose ester film.

[0008] In a preferred embodiment, the polyol ester plasticizer is an ester formed by the reaction of an aliphatic polyol and a monocarboxylic acid. Preferably, the polyol ester of the polyol ester plasticizer contains a cycloalkyl group.

[0009] In a preferred embodiment, the aliphatic polyol includes at least one of ribitol, arabinitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,3,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, and xylitol.

[0010] In a preferred embodiment, the monocarboxylic acid includes at least one of acyclic aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, and aromatic monocarboxylic acids.

[0011] In one preferred embodiment, the acyclic aliphatic monocarboxylic acid has 1-32 carbon atoms; more preferably, it has 1-20 carbon atoms; and even more preferably, it has 1-10 carbon atoms.

[0012] In a preferred embodiment, the acyclic aliphatic monocarboxylic acid includes saturated fatty acids and unsaturated fatty acids; the saturated fatty acids include, but are not limited to, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, nonanoic acid, decanoic acid, 2-ethylhexanecarboxylic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, docosanoic acid, icosanoic acid, heptadecanoic acid, nonadecanoic acid, triacontanoic acid, and tridodecanoic acid. The unsaturated fatty acids include, but are not limited to, undecenoic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

[0013] In one preferred embodiment, the alicyclic monocarboxylic acid includes, but is not limited to, cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and their derivatives.

[0014] In a preferred embodiment, the aromatic monocarboxylic acid includes, but is not limited to, benzoic acid, tolueneic acid, biphenyl carboxylic acid, naphtholic carboxylic acid, and their derivatives. Benzoic acid is further preferred.

[0015] In a preferred embodiment, the polyol ester plasticizer is an aromatic terminal ester plasticizer, the acid value of the polyol ester plasticizer is <0.5mgKOH / g, and the hydroxyl value of the polyol ester plasticizer is <17mgKOH / g.

[0016] In a preferred embodiment, the polyol ester plasticizer has an average molecular weight of 300-750 Da.

[0017] Photochromic cellulose ester films prepared using polyol ester plasticizers with an average molecular weight of 300-750 Da exhibit low volatility, good compatibility with cellulose esters, and excellent water vapor permeability.

[0018] In a preferred embodiment, the amount of the color-changing powder added is 0.3-1.5% of the total mass of the color-changing powder, polyol ester plasticizer, and cellulose ester, and the amount of the polyol ester plasticizer added is 5-15% of the total mass of the color-changing powder, polyol ester plasticizer, and cellulose ester.

[0019] The inventors discovered during experiments that adding 5-15% polyol ester plasticizer improved the anti-aging properties of the photochromic cellulose ester film, making it less prone to degradation, exhibiting low sealing degradation, and demonstrating good resistance to leaching. The likely reason is that the 5-15% polyol ester plasticizer, during aging in the photochromic cellulose ester film system, generates water. The polyol ester plasticizer degrades into benzoic acid, and the resulting alcohol absorbs the water produced during aging, giving the photochromic cellulose ester film excellent weather resistance and effectively extending the product's service life. Traditional plasticizers, on the other hand, degrade into phenol, which then transforms into benzoin, leading to yellowing after aging.

[0020] In a preferred embodiment, the polyol ester plasticizer has the following structural formula:

[0021]

[0022] At least one of them.

[0023] In a preferred embodiment, the thickness of the photochromic cellulose ester film is 100-200 μm.

[0024] In a preferred embodiment, the raw materials also include: solvent, cosolvent, matting agent, and dispersant.

[0025] In a preferred embodiment, the solvent is selected from at least one of dichloromethane, trichloromethane, and acetone.

[0026] In a preferred embodiment, the solvent is dichloromethane.

[0027] In a preferred embodiment, the co-solvent is selected from at least one of methanol, ethanol, propanol, and butanol.

[0028] In a preferred embodiment, the co-solvent is methanol.

[0029] In a preferred embodiment, the particle size of the matting agent is 50-100 μm, and the matting agent is selected from at least one of silicon dioxide and titanium dioxide.

[0030] In a preferred embodiment, the dispersant is glycerol.

[0031] In a preferred embodiment, the raw materials for preparing the photochromic cellulose ester film, by weight, include 1-3 parts of color-changing powder, 5-15 parts of polyol ester plasticizer, 80-120 parts of cellulose ester, 250-300 parts of solvent, 5-13 parts of co-solvent, 0.1-0.3 parts of matting agent, and 1-5 parts of dispersant.

[0032] In a preferred embodiment, the raw materials for preparing the photochromic cellulose ester film, by weight, include 1-2 parts of color-changing powder, 8-10 parts of polyol ester plasticizer, 90-110 parts of cellulose ester, 280-290 parts of solvent, 8-11 parts of co-solvent, 0.1-0.2 parts of matting agent, and 2-4 parts of dispersant.

[0033] In a preferred embodiment, the raw materials for preparing the photochromic cellulose ester film, by weight, include 1 part color-changing powder, 9 parts polyol ester plasticizer, 100 parts cellulose ester, 285 parts solvent, 9.5 parts co-solvent, 0.1 parts matting agent, and 3 parts dispersant.

[0034] A second aspect of the present invention provides a method for preparing a photochromic cellulose ester film, comprising the following steps:

[0035] S1 dissolves the color-changing powder in 15-20 wt% of total solvent and 8-12 wt% of total co-solvent to obtain a color-changing solution;

[0036] S2 dissolves cellulose ester and polyol ester plasticizer in 70-75 wt% total solvent and 70-75 wt% total co-solvent to obtain cotton glue solution;

[0037] S3. Mix the color-changing solution and cotton glue solution and stir for 1-3 hours, then filter to obtain the color-changing cotton glue solution.

[0038] S4. Dilute 5-7 wt% of the color-changing cotton glue solution to obtain dilute color-changing cotton glue solution I, dilute 1-3 wt% of the color-changing cotton glue solution to obtain dilute color-changing cotton glue solution II, mix dilute color-changing cotton glue solution I with a matting agent to obtain a matting solution, mix dilute color-changing cotton glue solution II with a dispersant to obtain a dispersion solution, and mix the matting solution, dispersion solution and remaining color-changing cotton glue solution evenly.

[0039] S5 The final product of step S4 is cast into a liquid film through a casting nozzle, then peeled off, dried and wound up to obtain a photochromic cellulose ester film.

[0040] In a preferred embodiment, the dilute color-changing cotton adhesive solution I comprises 5-7 wt% color-changing cotton adhesive solution, 7-8 wt% total solvent, and 0.1-0.2 wt% total co-solvent. The dilute color-changing cotton adhesive solution II comprises 11-13 wt% color-changing cotton adhesive solution, 1-3 wt% total solvent, and 5-6 wt% total co-solvent.

[0041] A third aspect of the present invention provides an application of a photochromic cellulose ester film in photochromic lenses.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The photochromic cellulose ester film of the present invention is prepared by using polyol ester plasticizer and color-changing powder. The polyol ester plasticizer has good compatibility in the photochromic cellulose ester film system, and the prepared photochromic cellulose ester film has a high appearance and excellent optical performance.

[0044] (2) The photochromic cellulose ester membrane of the present invention uses a polyol ester plasticizer with a special structure to prepare a photochromic cellulose ester membrane that changes color when the ring is opened and fades when the ring is closed, thus optimizing the color-changing space performance and giving the photochromic cellulose ester membrane excellent plasticity, excellent water-blocking effect and retention.

[0045] (3) The photochromic cellulose ester membrane of the present invention uses 5-15% polyol ester plasticizer and 0.3-1.5% photochromic powder, which improves the anti-aging performance of the photochromic cellulose ester membrane, makes it less prone to degradation, has low sealing degree, and good resistance to leakage.

[0046] (4) The photochromic cellulose ester film of the present invention uses a polyol ester plasticizer containing hydroxyl groups, which has good compatibility with cellulose ester, is not easy to precipitate, and improves the light fog resistance of the product.

[0047] (5) The photochromic cellulose ester membrane described in this invention can be processed on a basic cellulose ester membrane processing production line without the need for additional equipment investment, which is more in line with the principle of economic efficiency in production. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the equipment process for the production of this invention;

[0049] In the diagram: 1. Color-changing powder mixing vessel; 2. Cotton glue preparation vessel; 3. Filter; 4. Matting agent mixing vessel; 5. Dispersant mixing vessel; 6. Static mixer; 7. Casting nozzle; 8. Stainless steel belt; 9. Front drum; 10. Intermediate cover; 11. Dryer; 12. Rewinder. Detailed Implementation

[0050] Example 1

[0051] A photochromic cellulose ester film, wherein the raw materials for preparing the photochromic cellulose ester film, by weight, include 1 part of color-changing powder, 9 parts of polyol ester plasticizer, 100 parts of cellulose ester, 285 parts of solvent, 9.5 parts of co-solvent, 0.1 parts of matting agent, and 3 parts of dispersant.

[0052] The color-changing powder was purchased from Shenzhen Xingsheng Zhuguang Chemical Pigment Co., Ltd., with models L-purple and Z-green.

[0053] The cellulose ester is cellulose triacetate, purchased from Sichuan Push, model number H11872.

[0054] The solvent is dichloromethane, and the co-solvent is methanol;

[0055] The matting agent is silica with a particle size of 75 μm, purchased from Evonik, model R972.

[0056] The dispersant is methanol.

[0057] The polyol ester plasticizer is

[0058] (Purchased from Foshan Jinjia New Material Technology Co., Ltd., model FLER-705) and (Purchased from Foshan Jinjia New Material Technology Co., Ltd., model FLER-988) Combination, weight ratio is 8:1.

[0059] Adopting such Figure 1 The production equipment flow diagram shown is applied to the preparation method described below.

[0060] A method for preparing a photochromic cellulose ester film includes the following steps:

[0061] S1 Dissolves 1 kg of color-changing powder in 50 kg of solvent and 1 kg of co-solvent, and stirs in color-changing powder mixing vessel 1 for 1 hour to obtain color-changing solution;

[0062] S2 dissolves 100kg of cellulose ester and 9kg of polyol ester plasticizer in 210kg of solvent and 7kg of co-solvent, and stirs in cotton glue preparation kettle 2 for 4h to obtain cotton glue solution.

[0063] S3 mixes and stirs the color-changing solution and cotton glue solution for 2 hours, and then filters it through filter 3 to obtain the color-changing cotton glue solution;

[0064] S4 dilutes 5-7 wt% of the color-changing cotton glue solution into dilute color-changing cotton glue solution I, and dilutes 1-3 wt% of the color-changing cotton glue solution into dilute color-changing cotton glue solution II. Dilute color-changing cotton glue solution I is mixed with 0.1 kg of matting agent in matting agent mixing tank 4 to obtain a matting solution. Dilute color-changing cotton glue solution II is mixed with 3 kg of dispersant in dispersant mixing tank 5 to obtain a dispersion solution. The matting solution, dispersion solution and remaining color-changing cotton glue solution are mixed evenly through static mixer 6.

[0065] S5 The final product of step S4 is cast through the casting nozzle 7 onto the continuously running stainless steel belt 8 to form a liquid film. The liquid film is peeled off at the front drum 9, and after passing through the intermediate cover 10 and the dryer 11, it is dried and wound up to obtain a 130μm photochromic cellulose ester film.

[0066] The diluted color-changing cotton adhesive solution I comprises 20 kg of color-changing cotton adhesive solution, 20 kg of solvent, and 1 kg of co-solvent. The diluted color-changing cotton adhesive solution II comprises 5 kg of color-changing cotton adhesive solution, 5 kg of solvent, and 0.5 kg of co-solvent.

[0067] Example 2

[0068] A photochromic cellulose ester film and its preparation method are described. The specific implementation method is the same as in Example 1, except that 7 parts by weight of the polyol ester plasticizer are used. (Purchased from Foshan Jinjia New Material Technology Co., Ltd., model FLER-700) and

[0069] (Purchased from Foshan Jinjia New Material Technology Co., Ltd., model FLER-988) Combination, weight ratio 6:1.

[0070] The thickness of the photochromic cellulose ester film is 160 μm.

[0071] Example 3

[0072] A photochromic cellulose ester film and its preparation method are described. The specific implementation method is the same as in Example 1, except that the polyol ester plasticizer is 10 parts by weight. The polyol ester plasticizer is... (Purchased from Wuhan Yikede, model 314)

[0073] The thickness of the photochromic cellulose ester film is 160 μm.

[0074] Example 4

[0075] A photochromic cellulose ester film and its preparation method are described. The specific implementation method is the same as in Example 1, except that the polyol ester plasticizer is 12 parts by weight. The polyol ester plasticizer is... (Purchased from DIC Corporation, model EXP-6488) and

[0076] The combination of (purchased from Zhejiang Hetang Technology Co., Ltd., model ST-3) has a weight ratio of 10:2.

[0077] The thickness of the photochromic cellulose ester film is 175 μm.

[0078] Comparative Example 1

[0079] A photochromic cellulose ester film and its preparation method are described. The specific implementation method is the same as in Example 1, except that the polyol ester plasticizer is replaced with triphenyl phosphate, and the amount added is 10 parts by weight.

[0080] The thickness of the photochromic cellulose ester film is 130 μm.

[0081] Comparative Example 2

[0082] A photochromic cellulose ester film and its preparation method are described. The specific implementation method is the same as in Example 1, except that the polyol ester plasticizer is replaced with 4-biphenyl diphenyl phosphate, and the amount added is 12 parts by weight.

[0083] The thickness of the photochromic cellulose ester film is 160 μm.

[0084] Comparative Example 3

[0085] A photochromic cellulose ester film and its preparation method are described. The specific implementation method is the same as that in Example 1, except that the polyol ester plasticizer is replaced with a combination of 2-biphenyl diphenyl phosphate and dibutyl phthalate in a weight ratio of 10:2, and the total amount of 2-biphenyl diphenyl phosphate and dibutyl phthalate added is 12 parts by weight.

[0086] Performance testing

[0087] 1. Methods for determining color change, fading and durability: Two samples of the prepared photochromic cellulose ester membrane were taken. One sample was 3cm × 2cm and was labeled as sample A. The other sample was 4cm × 1cm and was labeled as sample B. Gloves were worn during the sampling process to prevent the membrane from being contaminated.

[0088] After sampling, the L, b*, and YI values ​​of sample A were tested. The transmittance at 550 nm was measured after 1 minute of light exposure and after 5 minutes of darkness. After testing, the sample was placed in a headspace vial, and the vial was marked on the outside. The vial containing the sample was equilibrated in a dual 85 aging chamber for 24 hours, then sealed and aged for 1000 hours using dual 85 aging. After aging, the L, b*, and YI values ​​of the sample were tested again, along with the transmittance at 550 nm after 1 minute of light exposure and after 5 minutes of darkness. The light exposure conditions were as follows: 1 minute of irradiation in a xenon lamp testing machine (170 mw / cm²), with a UV1700 / UV1800 UV meter used to measure the transmittance at 550 nm. After 5 minutes of darkness, the transmittance at 550 nm was measured using a UV1700 / UV1800 UV meter.

[0089] After sampling (sample B), the sample was placed in a headspace vial and marked on the outer wall. The vial containing the sample was equilibrated in a double 85 aging chamber for 24 hours, then sealed and aged at double 85 for 1000 hours. The condition of the sample was recorded at the end of aging. Durability was evaluated by visually observing the degree of film degradation. The evaluation criteria are as follows:

[0090] 5: No obvious bending or adhesion

[0091] 4: Samples are whitish, bent, and stuck together.

[0092] 3: Samples are yellowed, bent, and stuck together.

[0093] 2: Sample piece, brown, fragmented

[0094] 1: The sample is black, indicating degradation.

[0095] 3. Method for determining efflorescence resistance: The prepared photochromic cellulose ester membrane was cut into 10cm × 10cm pieces and placed in a constant temperature and humidity chamber at 85℃ and 85% relative humidity for 120 hours. The surface of the membrane was then visually observed to evaluate efflorescence resistance. The evaluation criteria are as follows:

[0096] 5: No liquid exudate or atomization caused by exudation.

[0097] 4: Atomization is caused by seepage from part of the surface.

[0098] 3: Atomization is caused by the seepage of the entire surface.

[0099] 2: Liquid seepage occurs on some surfaces.

[0100] 1: Liquid seepage occurs across the entire surface.

[0101] The test results are shown in Table 1.

[0102] Table 1

[0103]

[0104]

Claims

1. A photochromic cellulose ester film, characterized in that, The raw materials for preparation include at least: color-changing powder, polyol ester plasticizer, and cellulose ester. The general structural formula of the polyol ester plasticizer is as follows: B-(GA)nGB, where: B is a benzene monocarboxylic acid residue, G is an alkylene diol residue with 2-12 carbon atoms or an oxoalkylene diol residue with 4-12 carbon atoms, A is an alkylene dicarboxylic acid residue with 4-12 carbon atoms, and n is an integer ≥0.

2. The photochromic cellulose ester film according to claim 1, characterized in that, The polyol ester plasticizer is an aromatic terminal ester plasticizer, and the acid value of the polyol ester plasticizer is <0.5mgKOH / g, and the hydroxyl value of the polyol ester plasticizer is <17mgKOH / g.

3. The photochromic cellulose ester film according to claim 1, characterized in that, The average molecular weight of the polyol ester plasticizer is 300-750 Da.

4. The photochromic cellulose ester film according to claim 1, characterized in that, The amount of the color-changing powder added accounts for 0.3-1.5% of the total mass of the color-changing powder, polyol ester plasticizer, and cellulose ester, and the amount of the polyol ester plasticizer added accounts for 5-15% of the total mass of the color-changing powder, polyol ester plasticizer, and cellulose ester.

5. The photochromic cellulose ester film according to claim 1, characterized in that, The raw materials also include: solvents, cosolvents, matting agents, and dispersants.

6. The photochromic cellulose ester film according to claim 5, characterized in that, The solvent is selected from at least one of dichloromethane, trichloromethane, and acetone.

7. The photochromic cellulose ester film according to claim 5, characterized in that, The co-solvent is selected from at least one of methanol, ethanol, propanol, and butanol.

8. The photochromic cellulose ester film according to claim 5, characterized in that, The matting agent has a particle size of 50-100 μm and is selected from at least one of silicon dioxide and titanium dioxide.

9. A method for preparing a photochromic cellulose ester film according to any one of claims 5-8, characterized in that, Includes the following steps: S1 dissolves the color-changing powder in 15-20 wt% of total solvent and 8-12 wt% of total co-solvent to obtain a color-changing solution; S2 dissolves cellulose ester and polyol ester plasticizer in 70-75 wt% total solvent and 70-75 wt% total co-solvent to obtain cotton glue solution; S3. Mix the color-changing solution and cotton glue solution and stir for 1-3 hours, then filter to obtain the color-changing cotton glue solution. S4. Dilute 5-7 wt% of the color-changing cotton glue solution to obtain dilute color-changing cotton glue solution I, dilute 1-3 wt% of the color-changing cotton glue solution to obtain dilute color-changing cotton glue solution II, mix dilute color-changing cotton glue solution I with a matting agent to obtain a matting solution, mix dilute color-changing cotton glue solution II with a dispersant to obtain a dispersion solution, and mix the matting solution, dispersion solution and remaining color-changing cotton glue solution evenly. S5 The final product of step S4 is cast into a liquid film through a casting nozzle, then peeled off, dried and wound up to obtain a photochromic cellulose ester film.

10. An application of the photochromic cellulose ester film according to any one of claims 5-8, characterized in that, It is used in photochromic lenses.

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