Preparation method of yellow light absorbing dye for myopia prevention and myopia prevention paper

Abstract

The present application relates to papermaking technical field, especially to a kind of anti-myopia yellow light absorption dye preparation method and myopia protection paper.The present application discloses a kind of anti-myopia yellow light absorption dye preparation method, dye preparation is diazotized to p-nitroaniline, coupled with 2-(2-hydroxy-5-sulfonic acid group phenyl) benzotriazole, salting-out, then with zinc sulfate, sodium sulfide complex azo dye-zinc sulfide complex is obtained.The protection paper is made by 3D printing texture forming and multiple composite function layer, mixed dye, 3D printing net form paper is made of pulp;Coated with bottom layer composite fluid, spray nano-silicon dioxide to obtain first-stage processing paper;Pretreatment dye coating, crosslinking to obtain secondary processing paper;Hot-pressing copolymerization fiber membrane and fumigation are obtained.The paper can prevent myopia, and is suitable for writing and printing.

Description

Technical Field

[0001] This invention relates to the field of papermaking technology, and in particular to a method for preparing a yellow light-absorbing dye for myopia prevention and myopia protection paper. Background Technology

[0002] Myopia is becoming an increasingly serious problem worldwide, especially among teenagers, where its incidence is rising year by year. Myopia not only seriously affects an individual's quality of life, learning, and work efficiency, but can also lead to a series of serious eye complications such as retinal detachment and glaucoma, posing a long-term threat to personal health.

[0003] From the perspective of the causes of myopia, besides genetic factors, environmental factors, especially prolonged exposure to poor visual environments, are key factors in the occurrence and development of myopia. In daily study and work scenarios, paper is one of the most frequently encountered visual media. Traditional white paper has the characteristic of full-spectrum reflection, and the reflected light contains a large amount of short-wavelength blue light. This type of short-wavelength blue light has relatively high energy; prolonged exposure to the eyes can stimulate retinal cells, causing eye fatigue, dryness, and decreased vision, thereby increasing the risk of myopia. Spending several hours a day using white paper notebooks, books, and other study materials exposes the eyes to the strong reflected light of white paper for extended periods, easily leading to visual fatigue.

[0004] US Patent No. 7304117B2 discloses a reactive yellow dye for ophthalmic devices and a method for preparing related ophthalmic devices. The reactive yellow dye is prepared through two methods: one involves reacting an aromatic amine with a vinyl-containing acyl chloride or isocyanate after diazotization; the other involves reacting an aromatic alkylamine with a vinyl-containing acyl chloride, acid anhydride, or isocyanate to generate an unsaturated polymerizable amide or carbamate, which is then coupled with a diazonium salt of the aromatic amine. Subsequently, these azo-yellow dyes with vinyl polymerizable groups are free-radical copolymerized with acrylic monomers, or with siloxane oligomers containing hydrosilyl groups through a hydrosilylation reaction to produce ophthalmic devices with blue light absorption properties. This patented dye design primarily addresses the lack of hydrophilic groups in ophthalmic implants, resulting in poor compatibility with paper and other substrates, making it unsuitable for paper products. The organic solvents used in the preparation process have environmental implications; the lack of substrate surface structure optimization makes it difficult to adapt to practical needs such as writing and gloss control in paper, and its application is limited to the ophthalmic field, lacking versatility.

[0005] Chinese patent CN106868927B discloses a method for preparing environmentally friendly paper that protects eyesight. The paper matrix is ​​composed of a mixture of plant fibers, kaolin, water-resistant agents, and other components. The protective coating uses a modified melanin adhesive. The preparation process involves dissolving sodium metasilicate and 2-methyl-2,4-pentanediol in deionized water, adding carboxymethyl cellulose to dissolve it, then adding melanin powder and ethanol, followed by adding sodium ethylenediaminetetramethylenephosphonate, N-phenyl-3-aminopropyltrimethoxysilane, and diethanolamine. After stirring evenly, ethylene glycol is added, and the mixture is stirred and refluxed at 50-55°C for 30 minutes. The pH is then adjusted to 6 by cooling, and finally the adhesive is coated onto the paper matrix. The protective coating in this patent relies solely on modified melanin adhesive, which has a single function and lacks a synergistic optimization design for the absorption of ultraviolet and blue light. It does not involve improvements to the paper structure, such as texture design, and has limited effect on suppressing glare. The preparation process uses a variety of chemical reagents, which may have room for improvement in environmental friendliness. Furthermore, it does not clearly explain the long-term stability of the adhesive on paper and its impact on practical performance such as writing and printing.

[0006] Chinese patent CN104908482A discloses a yellow notebook for preventing myopia. The paper is preferably made from unbleached pulp, but the specific manufacturing process is not mentioned. It only specifies that the paper is yellow, reflects light at a wavelength of 580–595 nm, and has a brightness of 60%–85%. This patent relies solely on the optical properties of yellow paper to achieve its myopia-preventing function, without addressing the molecular design of the dye or the optimization of the paper structure. Its effectiveness and efficiency in absorbing blue and violet light may be limited. Furthermore, it does not consider the paper's lightfastness, writing comfort, or other practical properties, and long-term use may lead to fading and other problems, affecting the stability of its myopia-preventing effect.

[0007] In conclusion, there is an urgent need for functional dyes that are compatible with paper and can efficiently absorb blue and violet light. By optimizing the microstructure and using multi-layer design, glare suppression can be enhanced, balancing protection, practicality, and environmental friendliness, and an integrated technology system can be constructed. Summary of the Invention

[0008] To address the aforementioned problems, the present invention aims to provide a method for preparing a yellow light-absorbing dye for myopia prevention and a myopia-protective paper. The method for preparing the yellow light-absorbing dye for myopia prevention specifically includes the following steps:

[0009] S001, add p-nitroaniline to dilute sulfuric acid to dissolve it, slowly add sodium nitrite solution and stir to obtain a diazonium salt solution;

[0010] S002, 2-(2-hydroxy-5-sulfonylphenyl)benzotriazole is added to sodium carbonate solution and dissolved to obtain the coupling component solution;

[0011] S003, the diazonium salt solution is slowly added dropwise to the coupling component solution, the coupling reaction is treated, sodium chloride is added for salting out, and then the product is filtered, washed, recrystallized and vacuum dried to obtain the azo dye.

[0012] S004, the azo dye is added to ultrapure water and stirred, zinc sulfate solution is added and ultrasonically complexed, sodium sulfide solution is added dropwise, and the mixture is filtered, washed and dried to obtain the azo dye-zinc sulfide complex, denoted as the dye.

[0013] In step S001, the concentration of dilute sulfuric acid is 20%, and the dissolution conditions are 3℃, 300rpm / min until completely dissolved. The molar ratio of sodium nitrite to p-nitroaniline is 1.05:1, and the stirring conditions are 3℃, 300rpm / min, and 60min.

[0014] In step S002, the concentration of sodium carbonate solution is 50 mg / mL, the concentration of 2-(2-hydroxy-5-sulfonicophenyl)benzotriazole in the coupling component solution is 105 mg / mL, and the dissolution conditions are 8℃, 300 rpm / min, and pH value of 8-9.

[0015] In step S003, the molar ratio of p-nitroaniline in the diazonium salt solution to 2-(2-hydroxy-5-sulfonylphenyl)benzotriazole in the coupling component solution is 1:1. The coupling reaction conditions are 8℃, 300rpm / min, pH 8-9, and 1.5h. The mass ratio of sodium chloride to p-nitroaniline is 6:1. The salting-out treatment time is 30min. The filter cake is washed three times with saturated brine at 5-10℃. The filter cake is recrystallized with 50% ethanol aqueous solution. The vacuum drying conditions are 60℃, -0.09MPa, and 6h.

[0016] In step S004, the solid-liquid ratio of azo dye to ultrapure water is 1:10. The stirring conditions are 200 rpm / min for 30 min, the zinc sulfate solution concentration is 0.1 mol / L, the ultrasonic complexation conditions are 60℃, 150 W, 300 rpm / min for 2 h, the sodium sulfide solution concentration is 0.05 mol / L, and the amount of sodium sulfide solution added is 20% of the total volume of the reaction system. The washing treatment involves washing three times each with ultrapure water and anhydrous ethanol. The drying conditions are 50℃, -0.09 MPa for 12 h.

[0017] To achieve myopia protection, myopia-protective paper can be produced through multi-layer composite processing and 3D printing texture optimization, specifically including the following steps:

[0018] S101, the bottom composite solution is uniformly coated on the bottom layer of the base paper, and after drying, the nano silica dispersion is sprayed onto the paper surface and dried to obtain the first-grade treated paper.

[0019] S102, the dye is added to the dispersion solution and subjected to micro-jet homogenization, high-shear dispersion and ultrasonic dispersion treatment in sequence. Silane coupling agent is added and stirred to react, thus obtaining the pretreated dye.

[0020] S103, the pretreated dye is coated on the surface of the primary treated paper, dried, immersed in crosslinking agent, reacted, washed and dried, and this step is repeated once to obtain the secondary treated paper.

[0021] S104 involves hot-pressing the copolymer fiber film onto the surface of the secondary-treated paper, followed by fumigation and surface micro-roughening treatment to obtain myopia protection paper.

[0022] In step S102, the thickness of the wet film coated is 50 μm, the mass fraction of silica in the nano silica dispersion is 3%, the particle size is 100-200 nm, and 3 layers are sprayed with air.

[0023] The bottom composite solution is composed of a nanocellulose suspension and carboxymethyl chitosan, wherein the mass ratio of the nanocellulose suspension to carboxymethyl chitosan is 3:1, and specifically includes the following steps:

[0024] The nanocellulose suspension was mixed with carboxymethyl chitosan, and glutaraldehyde, a crosslinking agent accounting for 1% of the total mass of the mixture, was added. The mixture was stirred at 300 rpm / min for 20 min, and then aminosilane coupling agent accounting for 1% of the total mass of the mixture was added dropwise. The mixture was stirred at 600 rpm / min for 30 min to obtain the bottom composite solution.

[0025] The preparation of the base paper involves adding pulp to ultrapure water, stirring, then adding dye and γ-aminopropyltriethoxysilane, mixing, and then performing 3D printing of a screen, vacuum papermaking, and drying to obtain the base paper with a textured structure. The stirring conditions were 300 rpm / min for 10 min, the dye-to-pulp mass ratio was 1:50, the amount of γ-aminopropyltriethoxysilane added was 0.2%, and the mixing conditions were 300 rpm / min for 20 min. The 3D printing screens used were flowers, triangles, and honeycombs. The flower petals had a diameter of 3 mm ± 0.05 mm and a depth of 0.4 mm ± 0.05 mm; the triangles had an angle of 60° ± 1° and a tooth depth of 0.3 mm ± 0.05 mm; the honeycombs had a pore size of 2 mm ± 0.05 mm and a depth of 0.5 mm ± 0.05 mm; the vacuum papermaking was performed at -0.09 MPa for 2 min; and the drying conditions were 60℃ for 2 h.

[0026] In step S103, the dispersion solution is an aqueous solution of sodium hexametaphosphate, and the amount used is 1% of the dye mass. The conditions for microfluidic homogenization are 150 MPa and 4 cycles. The conditions for high-shear dispersion are 10000 rpm / min and 20 min. The conditions for ultrasonic dispersion are 500 W and 30 min. The silane coupling agent is γ-aminopropyltriethoxysilane, and the amount used is 2% of the dye mass. The conditions for stirring reaction are 50℃, pH 8-9, and 3 h.

[0027] In step S104, the thickness of the wet film coated is 30 μm. The drying conditions are 40℃ for 15 min and 60℃ for 30 min. The crosslinking agent is 1% glutaraldehyde. The reaction time is 20 min. The washing process is performed by washing 5 times with ultrapure water.

[0028] In step S105, the hot pressing treatment is first hot-pressed at 50℃ and 0.5MPa for 15s, then heated to 60℃ and hot-pressed at 0.5MPa for 15s, and finally heated to 70℃ and hot-pressed at 0.5MPa for 15s. The fumigation treatment conditions are 60℃ for 8min, using perfluorooctyltriethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane with a mass ratio of 7:3. The surface micro-roughening treatment is performed using a plasma etching instrument with a power of 100W, an internal gas pressure of 5Pa, an oxygen flow rate of 10sccm, and 30s.

[0029] The copolymer fiber membrane is composed of methacrylic acid, 2,2,2-trifluoroethyl acrylate, additives, and hydroxyethyl cellulose. The mass ratio of methacrylic acid to 2,2,2-trifluoroethyl acrylate is 3:2, and the concentration of 2,2,2-trifluoroethyl acrylate is 35%. The mixed volatile solvent is composed of N,N-dimethylformamide and acetone in a volume ratio of 7:3. The additives consist of 5 wt% of photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 12 wt% polyvinylpyrrolidone. The specific steps include:

[0030] Methacrylic acid and 2,2,2-trifluoroethyl acrylate are added to a mixed volatile solvent, along with additives and hydroxyethyl cellulose. The mixture is stirred, electrospun, and cured to obtain a copolymer fiber membrane.

[0031] The addition amount of hydroxyethyl cellulose was 5% of the total system mass. The stirring conditions were 300 rpm / min for 20 min. The electrospinning conditions were 18 kV voltage, 1.0 mL / h flow rate, 12 cm receiving distance, and 40% RH. The curing treatment used a 365 nm ultraviolet light source with an intensity of 30 mW / cm². 2 Curing time is 10 minutes.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. This invention utilizes 2-(2-hydroxy-5-sulfonicophenyl)benzotriazole as the key functional group. The benzotriazole ring, with its unique conjugated π-electron system, undergoes energy level transitions with ultraviolet photons, efficiently capturing ultraviolet light through an intramolecular charge transfer mechanism, converting light energy into harmless heat energy. The hydroxyl and azo groups construct an extended conjugated system through π-π conjugation, enhancing the molecule's absorption capacity for blue light and achieving redshift modulation of the absorption peak. The sulfonic acid group, as a strongly hydrophilic functional group, not only improves the dispersion stability of the dye in aqueous solution through ion-dipole interactions but also optimizes the interfacial bonding force with the matrix material by enhancing molecular polarity. These three components work synergistically to achieve modulation of the absorption spectrum. Traditional azo dyes rely on a single coupling component, resulting in a short conjugated system, narrow absorption peaks, and an inability to cover the blue light band; furthermore, the lack of hydrophilic groups leads to uneven dispersion in pulp, resulting in fluctuating protective effects. The coupling of p-nitroaniline with 2-(2-hydroxy-5-sulfonylphenyl)benzotriazole forms a long conjugated chain, shifting the absorption peak to the blue light band and improving blue light blocking efficiency. The sulfonic acid group enhances the water solubility of the dye, ensuring uniform dispersion in pulp and preventing localized over-dyeing or light leakage. The low-temperature conditions of diazotization and coupling inhibit the decomposition of diazonium salts, reducing byproduct content and improving dye purity.

[0034] 2. This invention is based on the synergistic mechanism of coordination chemistry and photophysics. Utilizing the strong coordinating ability of zinc ions, it specifically binds to the hydroxyl and sulfonic acid groups in the molecular structure of azo dyes to form coordinate bonds. These coordinate bonds have high bond energies, giving the complexed system resistance to photolysis. Under specific reaction conditions, zinc ions act as the central ion, bridging the azo dye and sulfide ions through coordination to form an azo dye-zinc sulfide complex. The resulting zinc sulfide nanoparticles exhibit unique photophysical properties, enabling them to effectively absorb ultraviolet light. On one hand, the zinc sulfide nanoparticles scatter incident ultraviolet light to non-interacting regions through surface plasmon resonance, forming a physical shielding layer. On the other hand, the zinc ions in the ternary complex interact with the azo groups via electron cloud interaction, significantly increasing the excited state energy level of the azo bonds and suppressing the ultraviolet-induced homolytic cleavage of azo bonds, thus achieving the dual functions of ultraviolet protection and dye stability. After complexation treatment, the dye exhibits certain resistance to ultraviolet aging and fading, improving its lightfastness. The scattering effect of zinc sulfide nanoparticles enhances ultraviolet scattering rate, synergistically improving UV-B blocking rate in conjunction with dye absorption. Ultrasonic treatment promotes the coordination reaction between zinc ions and dyes, increasing the complexation rate and resulting in a more uniform particle size distribution of the complexes.

[0035] 3. This invention employs an integrated processing technology that simultaneously mixes dye and pulp. Utilizing 3D-printed mesh fabric with microstructures such as flowers, triangles, and honeycomb, micron-level grooves, protrusions, and pores on the mesh surface create directional flow paths, guiding the fibers to achieve orderly deposition during dehydration. The sulfonic acid groups in the dye molecules interact strongly with the hydroxyl groups of the pulp fibers through ion-dipole interactions. Combined with the bridging effect of γ-aminopropyltriethoxysilane, the dye is firmly anchored to the fiber surface and microstructure gaps, preventing localized penetration due to texture unevenness. Simultaneously, the rigid structure formed by the azo dye-zinc sulfide complex fills the fiber gaps at texture protrusions, forming a dense protective layer that further blocks penetration. In the vacuum papermaking stage, the system uses a high-vacuum negative pressure environment to rapidly remove moisture from the wet paper web. During this process, the stable structure formed by the dye complexation reaction is less prone to migration with moisture, ensuring uniform dye distribution and minimal penetration in the textured areas. This process integrates the three independent steps of dye loading, texture forming, and paper curing in the traditional process into continuous production. This reduces the raw material loss, increased energy consumption, cumbersome procedures, low dye utilization, and environmental pollution associated with the traditional paper-making-then-dyeing process. Simultaneously, it endows the paper with unique three-dimensional textures and color expressiveness. The integrated process shortens the production cycle, improves dye utilization, and increases production capacity. The 3D-printed flower, triangle, and honeycomb structures can directionally scatter strong light, reducing glare intensity and eye strain. γ-aminopropyltriethoxysilane bridges the dye and cellulose through silicon-oxygen bonds, improving binding strength and abrasion resistance.

[0036] 4. This invention employs a three-layer structure design: bottom anchoring, intermediate reinforcement, and surface functional adaptation. Each layer's function is synergistically based on material properties, increasing the surface's adaptability for writing and printing. It upgrades the traditional single-function coating to a multi-dimensional responsive system, achieving a trinity of mechanical reinforcement, optical protection, and functional adaptation through molecular-level interface control and micro / nano structure construction. The bottom layer, a composite reinforcement layer of nanocellulose and carboxymethyl chitosan, features a strong hydrogen bond network formed by the high-density hydroxyl groups of nanocellulose and the base cellulose molecular chains, firmly embedded in the paper fiber structure and enhancing interlayer bonding. Under the action of the cross-linking agent glutaraldehyde, carboxymethyl chitosan constructs a three-dimensional network support framework through a Schiff base reaction. After freeze-drying, it forms a nanoporous structure with controllable porosity, improving the paper's tensile strength, increasing folding endurance, and resisting dimensional expansion caused by temperature and humidity changes. The intermediate layer, a pre-treated dye and zinc sulfide photofunctional control layer, uses microfluidic homogenization technology to refine the organic dye, forming core-shell composite particles with zinc sulfide. After surface modification with a silane coupling agent, particles form a gradient distribution in the coating, achieving a tight arrangement through intermolecular π-π stacking and hydrogen bonding. This layer improves blue light blocking rate and reduces ultraviolet transmittance. Simultaneously, the siloxane network formed on the particle surface by the silane coupling agent enhances interlayer peel strength. The surface fluorocarbon fiber film, through gradient hot pressing and low-temperature oxygen plasma etching, constructs a dual roughness structure of micron-level protrusions and nano-level grooves, retaining stain resistance while improving the wettability and adhesion of inks and toners, achieving compatibility between writing and printing functions. Traditional protective paper surface coatings either have too low surface energy, making ink adhesion difficult, or too high surface polarity, leading to decreased water resistance; moreover, single-layer structures cannot balance protection, mechanical properties, and writing compatibility. The bottom nanocellulose network improves the paper's tensile strength and folding endurance, with high wet strength retention, solving the problem of paper deformation during writing and printing. The intermediate layer, after multiple cross-linking treatments, has uniform dye distribution and stable blue light blocking rate, ensuring that protective performance is unaffected by subsequent processing. The introduction of moderate polarity through the hydroxyl groups of hydroxyethyl cellulose and the pyrrolidone groups of polyvinylpyrrolidone enhances surface energy, improves wettability, reduces writing resistance, and enables continuous writing without ink breaks. The nanoscale pits formed by plasma etching improve ink absorption in inkjet printers and enhance toner adhesion in laser printers through a mechanical anchoring effect. After fumigation, the surface layer is both stain- and moisture-proof, preventing paper wrinkling during writing. The silane coupling agent γ-aminopropyltriethoxysilane connects the layers through silicon-oxygen bonds, enhancing interlayer peel strength. Gradient hot pressing prevents thermal shrinkage of the fiber membrane, ensuring surface smoothness to meet the demands of high-precision printing and resolving the inherent trade-off between protection and practicality in traditional protective materials. Attached Figure Description

[0037] Figure 1 It is a microstructure diagram of flower texture;

[0038] Figure 2 It is a diagram of the triangular texture microstructure;

[0039] Figure 3 It is a microstructure diagram of honeycomb texture. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments.

[0041] Example 1

[0042] A method for preparing an azo dye containing 2-(2-hydroxy-5-sulfonylphenyl)benzotriazole specifically includes the following steps:

[0043] Weigh 5g of p-nitroaniline and add it to 100mL of 20% dilute sulfuric acid. Stir at 3℃ and 300rpm / min until completely dissolved. Slowly add 20mL of 1.9mmol / mL sodium nitrite solution and stir at 3℃ and 300rpm / min for 60min to obtain the diazonium salt solution.

[0044] Weigh 10.5g of 2-(2-hydroxy-5-sulfonylphenyl)benzotriazole and add it to 100mL of 50mg / mL sodium carbonate solution. Adjust the pH to 8-9 at 8℃ and 300rpm / min until completely dissolved to obtain the coupling component solution.

[0045] The diazonium salt solution was slowly added dropwise to the coupling component solution. The pH was adjusted to 8-9 at 8℃ and 300 rpm / min, and the coupling reaction was carried out for 1.5 h. 30 g of sodium chloride was added for salting out for 30 min. The filter cake was obtained by suction filtration and washed three times with saturated brine at 5-10℃. The filter cake was recrystallized with 50% ethanol aqueous solution and dried at 60℃ and -0.09 MPa for 6 h to obtain the azo dye, which is designated as test sample 1.

[0046] Example 2

[0047] A method for preparing an azo dye-zinc sulfide complex specifically includes the following steps:

[0048] Weigh 5g of the azo dye prepared in Example 1 and add it to 50mL of ultrapure water. Stir at 200rpm / min for 30min, add 20mL of 0.1mol / L zinc sulfate solution, and sonicate at 60℃, 150W, and 300rpm / min for 2h. Add 14mL of 0.05mol / L sodium sulfide solution dropwise, filter, and wash three times each with ultrapure water and anhydrous ethanol. Dry at 50℃ and -0.09MPa for 12h to obtain the azo dye-zinc sulfide complex, which is test sample 2.

[0049] Example 3

[0050] A method for preparing paper for a 3D printing microstructure integrated process includes the following steps:

[0051] Weigh 100g of pulp and add it to 10L of ultrapure water. Stir at 300rpm / min for 10min. Add 2g of dye and 0.2g of γ-aminopropyltriethoxysilane and mix at 300rpm / min for 20min. Use 3D printing to create flower, triangle and honeycomb mesh molds respectively. Place them in a vacuum paper machine and dehydrate under a vacuum of -0.09MPa for 2min. Dry at 60℃ for 2h to obtain test sample 3.

[0052] The flower petals have a diameter of 3mm ± 0.05mm and a depth of 0.4mm ± 0.05mm. Figure 1 As shown in the flower pattern, the triangle angle is 60°±1°, and the tooth depth is 0.3mm±0.05mm, as... Figure 2 As shown in the triangular texture, the honeycomb pore size is 2mm ± 0.05mm, and the depth is 0.5mm ± 0.05mm. Figure 3 As shown in the honeycomb texture.

[0053] Example 4

[0054] A method for preparing a three-layer protective paper includes the following steps:

[0055] The bottom composite solution was uniformly coated onto the bottom layer of the base paper prepared in Example 3, with a wet film thickness of 50 μm. It was dried at 60°C for 2 hours. Three layers of a 3% nano-silica dispersion were sprayed onto the paper surface and dried at 60°C for 2 hours to obtain the first-grade treated paper.

[0056] Weigh 1g of dye, add 10mg of dispersion solution, and perform micro-fluid homogenization at 150MPa for 4 cycles, high shear dispersion at 10000rpm / min for 20min, ultrasonic dispersion at 500W for 30min, add silane coupling agent, and stir at 50℃ and pH 8-9 for 3h to obtain the pretreated dye.

[0057] The pretreated dye was coated on the surface of the primary treated paper with a wet film thickness of 30 μm. It was first dried at 40℃ for 15 min, then dried at 60℃ for 30 min, immersed in 1% glutaraldehyde crosslinking agent and reacted for 20 min. It was then washed 5 times with ultrapure water and dried at 60℃ for 2 h. This step was repeated once to obtain the secondary treated paper.

[0058] The copolymer fiber film was hot-pressed at 50℃ and 0.5MPa for 15s, then heated to 60℃ and hot-pressed at 0.5MPa for 15s, and finally heated to 70℃ and hot-pressed at 0.5MPa for 15s onto the surface of the secondary treated paper. Perfluorooctyltriethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane in a mass ratio of 7:3 were fumigated at 60℃ for 8min. The surface was then micro-roughened using a plasma etching instrument with a power of 100W, an internal air pressure of 5Pa, an oxygen flow rate of 10sccm, and 30s. This yielded the myopia protection paper, which was designated as test sample 4.

[0059] Comparative Example 1

[0060] A method for preparing a conventional benzotriazole ring-free and sulfonic acid group-free azo dye, the specific method including the following:

[0061] The difference from Example 1 is that conventional phenol was used instead of 2-(2-hydroxy-5-sulfonicophenyl)benzotriazole, with a weighing mass of 3.41 g, a salting-out time of 1 h, and after filtration, the filter cake was washed three times with ultrapure water at 5-10 °C and dried at 60 °C and -0.09 MPa for 6 h. The rest was prepared according to the method of Example 1 to obtain a conventional benzotriazole ring-free and sulfonic acid azo dye, which is designated as reference standard 1.

[0062] Comparative Example 2

[0063] A method for preparing an azo dye containing only a benzotriazole ring and lacking hydroxyl and sulfonic acid groups, the specific method comprising the following steps:

[0064] The difference from Example 1 is that 2-phenylbenzotriazole is used instead of 2-(2-hydroxy-5-sulfonylphenyl)benzotriazole, wherein the weighing mass is 7.07 g, and the remainder is prepared according to the method of Example 1 to obtain an azo dye containing only a benzotriazole ring and lacking hydroxyl and sulfonic acid groups, which is designated as reference standard 2.

[0065] Comparative Example 3

[0066] A method for preparing an azo dye containing only sulfonic acid groups and lacking a benzotriazole ring, the specific method comprising the following steps:

[0067] The difference from Example 1 is that p-hydroxybenzenesulfonic acid is used instead of 2-(2-hydroxy-5-sulfonicophenyl)benzotriazole, wherein the weighing mass is 6.31 g, and the remainder is prepared according to the method of Example 1 to obtain an azo dye containing only sulfonic acid groups and lacking the benzotriazole ring, which is designated as reference standard 3.

[0068] Comparative Example 4

[0069] Example 1 describes the preparation of a dye using a non-low-temperature reaction method, specifically including the following steps:

[0070] The difference from Example 1 is that the 3°C for diazotization and the 8°C for the coupling reaction were changed to room temperature, while the rest were prepared according to the method of Example 1 to obtain control product 4.

[0071] Comparative Example 5

[0072] A method for preparing an azo dye-copper sulfide complex specifically includes the following steps:

[0073] The difference from Example 2 is that copper sulfate solution was used instead of zinc sulfate solution, the concentration of copper sulfate solution was 0.1 mol / L, and the rest was prepared according to the method of Example 2 to obtain reference standard 5.

[0074] Comparative Example 6

[0075] A method for preparing an azo dye coordinated only by zinc ions, specifically including the following steps:

[0076] The difference from Example 2 is that sodium sulfide solution was not added, and the control sample 6 was prepared according to the method of Example 2.

[0077] Comparative Example 7

[0078] A method for preparing paper that simulates the traditional process of papermaking followed by coating specifically includes the following steps:

[0079] Weigh 100g of pulp, add 10L of ultrapure water to disperse it, use flat wire vacuum papermaking, and dry at 60℃ for 2 hours to obtain blank paper.

[0080] Weigh 2g of dye and dissolve it in 10L of ultrapure water. Immerse blank paper in the dye solution for 30 minutes, remove and drain, and dry at 60℃ for 2 hours to obtain reference standard 7.

[0081] Comparative Example 8

[0082] A method for preparing an integrated process paper without 3D microstructures specifically includes the following steps:

[0083] The difference from Example 3 is that a flat mesh is used instead of a 3D printed mesh, and the control sample 8 is prepared according to the method of Example 3.

[0084] Comparative Example 9

[0085] A method for preparing a single-layer protective paper includes the following steps:

[0086] The difference from Example 1 is that only the intermediate functional layer is coated, without the bottom layer and the top layer.

[0087] The pretreated dye obtained in Example 4 was coated onto the surface of the base paper obtained in Example 3, with a wet film thickness of 30 μm. It was first dried at 40°C for 15 min, then dried at 60°C for 30 min, immersed in 1% glutaraldehyde crosslinking agent, reacted for 20 min, washed 5 times with ultrapure water, dried at 60°C for 2 h, and this step was repeated once to obtain control product 9.

[0088] Comparative Example 10

[0089] A method for preparing a double-layer protective paper lacking a bottom layer specifically includes the following steps:

[0090] The difference from Example 1 is that the intermediate layer and the top layer are directly coated on the surface of the textured paper, without the bottom reinforcement layer.

[0091] The copolymer fiber membrane was hot-pressed at 50℃ and 0.5MPa for 15s, then heated to 60℃ and hot-pressed at 0.5MPa for 15s, and finally heated to 70℃ and hot-pressed at 0.5MPa for 15s onto the surface of reference 9. The membrane was then fumigated at 60℃ for 8min with perfluorooctyltriethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane in a mass ratio of 7:3. The surface was then micro-roughened using a plasma etching instrument with a power of 100W, an internal pressure of 5Pa, an oxygen flow rate of 10sccm, and a duration of 30s to obtain reference 10.

[0092] Comparative Example 11

[0093] A method for preparing a double-layer protective paper lacking a surface layer specifically includes the following steps:

[0094] The difference from Example 1 is that a bottom layer and an intermediate layer are prepared, but no surface copolymer fiber membrane is used.

[0095] The bottom composite solution was uniformly coated onto the base paper bottom layer prepared in Example 3, with a wet film thickness of 50 μm. It was dried at 60°C for 2 hours. Three layers of a 3% nano silica dispersion were sprayed onto the paper surface and dried at 60°C for 2 hours to obtain the treated paper.

[0096] The pretreated dye obtained in Example 4 was coated onto the surface of the treated paper, with a wet film thickness of 30 μm. The paper was first dried at 40°C for 15 min, then dried at 60°C for 30 min, immersed in 1% glutaraldehyde crosslinking agent, reacted for 20 min, washed 5 times with ultrapure water, dried at 60°C for 2 h, and this step was repeated once to obtain control product 11.

[0097] Comparative Example 12

[0098] A method for preparing a traditional three-layer protective paper surface layer specifically includes the following steps:

[0099] The difference from Example 1 is that epoxy resin was used instead of copolymer fiber membrane, and the rest was prepared according to the method of Example 4 to obtain control product 12.

[0100] Experimental Example 1

[0101] This experimental example tests the absorption spectrum and blocking rate, water solubility and dispersibility, and azo dye purity of the test sample in Example 1 and the control samples in Comparative Examples 1-4. The specific steps include:

[0102] 1. Absorption spectroscopy and barrier rate testing:

[0103] Weigh 0.01g of each of the following azo dyes: test sample 1, reference sample 1, reference sample 2, and reference sample 3. Dissolve them in an appropriate amount of ultrapure water, transfer them to a 100mL volumetric flask, and dilute to the mark with ultrapure water to prepare a 0.1mg / mL solution.

[0104] Using ultrapure water as a reference, a UV-Vis spectrophotometer was used to scan in the blue light 380–500 nm and UV-B 280–320 nm bands, and each sample was tested three times.

[0105] The blocking rate and the wavelength of the absorption peak were calculated by subtracting 10 from the negative power of absorbance. The results are shown in Table 1-1.

[0106] Table 1-1 Absorption Spectrum and Barrier Rate Test

[0107] sample Absorption peak wavelength (nm) Blue light blocking rate (%) UV-B blocking rate (%) Example 1 451.7±1.5 84.5±0.4 81.4±0.4 Comparative Example 1 374.7±1.5 41.6±0.8 58.6±0.5 Comparative Example 2 390.0±2.0 59.6±0.5 76.0±0.6 Comparative Example 3 410.0±2.0 72.0±0.4 47.1±0.7

[0108] As shown in Table 1-1, Example 1, due to the introduction of 2-(2-hydroxy-5-sulfonicophenyl)benzotriazole, is superior to the comparative example in all aspects of absorption peak wavelength, blue light blocking rate, and UV-B blocking rate, demonstrating the key optimization role of this structure in the optical performance of the dye. Comparative Example 1, lacking the benzotriazole ring and sulfonic acid group, showed a blue shift in absorption peak and a significant decrease in blue light and UV-B blocking rate after phenol was substituted, indicating that the benzotriazole ring and sulfonic acid group are the core structures for improving blocking performance. Comparative Example 2, containing only the benzotriazole ring but lacking the hydroxyl and sulfonic acid groups, still showed lower absorption peak and blocking rate than Example 1, proving that the hydroxyl and sulfonic acid groups can synergistically enhance the blocking effect. Comparative Example 3, containing only the sulfonic acid group but lacking the benzotriazole ring, showed some improvement in absorption peak and blue light blocking rate, but the UV-B blocking rate was significantly reduced, highlighting the unique role of the benzotriazole ring in UV-B band protection.

[0109] In summary, the synergistic effect of the benzotriazole ring, hydroxyl group, and sulfonic acid group of 2-(2-hydroxy-5-sulfonicophenyl)benzotriazole is the fundamental reason for the red shift in the absorption spectrum and the excellent blocking performance of the dye in Example 1. This structural design provides an effective solution for azo dyes in the fields of blue light and UV-B protection.

[0110] 2. Water solubility and dispersibility test:

[0111] Take 50 mL of ultrapure water, add 2 g of test sample 1, reference sample 1, reference sample 2, and reference sample 3 azo dye, stir at 25℃ and 300 rpm / mL for 30 min until undissolved solid appears in the solution, which means it is saturated. Filter, weigh the mass of undissolved dye, and repeat the test 3 times for each sample.

[0112] The saturated solubility was calculated by the ratio of the difference between the total added mass and the mass of undissolved dye to the volume of ultrapure water. The results are shown in Table 1-2.

[0113] Add 0.2g of test sample 1, reference sample 1, reference sample 2, and reference sample 3 dyes and 10g of pulp to 100mL of ultrapure water, stir for 10min, pour into a stoppered graduated cylinder, and let stand for 1h.

[0114] Observe the stratification phenomenon, take the upper suspension, and use a laser particle size analyzer to test the particle size distribution from 0.1 to 1000 μm. Calculate the particle size distribution span by the ratio of the difference between particle size distributions D90 and D10 to D50. The results are shown in Table 1-2.

[0115] Table 1-2 Water solubility and dispersibility tests

[0116] sample Saturated solubility (g / L) Stratification Particle size distribution span Example 1 30.0±1.1 Uniform and without layering 1.36±0.05 Comparative Example 1 1.5±0.1 Obvious aggregation and sedimentation 1.62±0.01 Comparative Example 2 3.0±0.4 Slight sedimentation 1.84±0.01 Comparative Example 3 14.0±0.4 Slight stratification, with a small amount of sediment at the bottom. 1.47±0.01

[0117] As shown in Tables 1-2, Example 1, containing the benzotriazole ring of 2-(2-hydroxy-5-sulfonicophenyl)benzotriazole, achieved a solubility of 30.0 ± 1.1 g / L, significantly higher than the comparative example. Comparative Example 1, using phenol and lacking the benzotriazole ring and sulfonic acid group, had a solubility of only 1.5 ± 0.1 g / L; Comparative Example 2, containing only the benzotriazole ring but lacking the hydroxyl and sulfonic acid groups, had a solubility of 3.0 ± 0.4 g / L; and Comparative Example 3, containing only the sulfonic acid group but lacking the benzotriazole ring, had a solubility of 14.0 ± 0.4 g / L. This indicates that the benzotriazole ring, hydroxyl, and sulfonic acid groups synergistically enhance water solubility, demonstrating the significant effect of multifunctional groups. Example 1 was homogeneous without stratification, Comparative Example 1 showed obvious agglomeration and precipitation, Comparative Example 2 showed slight precipitation, and Comparative Example 3 showed slight stratification and a small amount of sediment at the bottom. The results show that the structure of Example 1 makes the dye more stably dispersed in the system. The comparative examples, lacking key functional groups, are prone to aggregation and precipitation. Example 1, with its higher functional group integrity, exhibits better dispersion stability. The particle size distribution range of Example 1 is 1.36±0.05, compared to 1.62±0.01 for Comparative Example 1, 1.84±0.01 for Comparative Example 2, and 1.47±0.01 for Comparative Example 3, all showing larger ranges. A smaller range indicates a more concentrated particle size distribution and better dispersibility, further verifying that the multi-functional group synergistic structure of Example 1 results in more uniform dye dispersion. The comparative examples, due to structural defects such as missing / replaced functional groups, exhibit poor dispersibility and a wide particle size distribution.

[0118] In summary, the synergistic effect of the benzotriazole ring, hydroxyl group, and sulfonic acid group of 2-(2-hydroxy-5-sulfonicophenyl)benzotriazole is key to the good water solubility and stable dispersion of the dye in Example 1. The comparative examples, due to their single or missing functional groups, exhibit poor water solubility and dispersibility. This structural design provides advantages for azo dyes in applications requiring good dissolution and dispersion.

[0119] 3. Azo dye purity test:

[0120] Weigh 0.01g of test sample 1 and reference sample 4 azo dye respectively, dissolve them in an appropriate amount of methanol, transfer them to a 100mL volumetric flask, and dilute to the mark with methanol. Filter through a 0.22μm organic phase membrane.

[0121] The chromatographic column was C18, 250 mm × 4.6 mm × 5 μm, the mobile phase was 70% methanol aqueous solution, the flow rate was 1.0 mL / min, the detection wavelength was 450 nm, the injection volume was 10 μL, and each sample was tested three times.

[0122] The purity of the azo dye was calculated based on the ratio of the main peak area to the total peak area, and the results are shown in Table 1-3.

[0123] Table 1-3 Azo dye purity test

[0124] sample Azo dye purity (%) Example 1 95.3±0.1 Comparative Example 4 79.9±0.4

[0125] As shown in Tables 1-3, Example 1, using a low-temperature process of diazotization at 3°C ​​and coupling at 8°C, achieved a dye purity of 95.3±0.1%; Comparative Example 4, with a reaction at room temperature, saw its purity decrease to 79.9±0.4%. The low-temperature environment can suppress side reactions such as diazonium salt decomposition and the formation of coupling byproducts, making the reaction more selective and ensuring the formation of the main product; at room temperature, the reaction activity is high, leading to more side reactions and impurity residues that reduce purity.

[0126] This indicates that low-temperature reaction is a key process for improving the purity of azo dyes. The temperature control strategy in Example 1 provides an effective technical path for the synthesis of high-purity azo dyes.

[0127] Experimental Example 2

[0128] This experimental example tests the lightfastness, UV-B blocking rate, complexation structure, and performance of the test samples from Examples 1-2 and the control samples from Comparative Examples 5-6. The specific steps include:

[0129] 1. Lightfastness test:

[0130] Weigh 0.1g of each of the following samples: test sample 1, test sample 2, reference sample 5, and reference sample 6. Add 10mL of anhydrous ethanol, sonicate at 150W for 10min, coat onto a glass slide, and dry at 60℃ for 30min to form a uniform dye film. Prepare 6 slides for each group.

[0131] Placed at 280–320 nm, 0.8 W / m 2 One sample was taken out in a light aging test chamber at 40℃ and 50%RH at 0h, 20h, 40h, 60h, 80h and 100h respectively, cooled to room temperature and the absorbance of the sample in the blue light 380~500nm and UV-B 280~320nm bands was measured with a UV-Vis spectrophotometer.

[0132] Based on the absorbance of the unaged sample, the retention rate was calculated according to the ratio of the absorbance of the aged sample to that of the unaged sample. The results are shown in Table 2-1.

[0133] Table 2-1 Lightfastness Test

[0134]

[0135] As shown in Table 2-1, Sample 1 is an azo dye containing a specific benzotriazole structure, Sample 2 is its complex with zinc sulfide, Reference 5 is an azo dye-copper sulfide complex, and Reference 6 is an azo dye coordinated only by zinc ions. In the lightfastness test, the retention rate changes with aging time, reflecting the material's resistance to photodegradation. Sample 2 showed the highest retention rates for both blue light and UV-B: 83.8% for blue light and 92.3% for UV-B at 20 hours; and 64.1% for blue light and 70.4% for UV-B at 100 hours. This indicates that the complexation of the azo dye with zinc sulfide significantly improves lightfastness, and the complexed structure enhances resistance to photoaging. Sample 1 showed a lower retention rate than Sample 2, indicating that the lightfastness of azo dye alone is weaker than that of the complex, and zinc sulfide complexation is the key modification for improving lightfastness. Reference standard 6 had a lower retention rate than test standard 2, indicating that zinc ion coordination alone is not as effective as the zinc sulfide complex formed by zinc ions and sodium sulfide. The complete zinc sulfide complex structure has a more significant effect on optimizing lightfastness. Reference standard 5 had the lowest retention rate, reflecting the difference in complexing effects of different metal sulfides. Zinc sulfide is superior to copper sulfide in improving the lightfastness of azo dyes.

[0136] In summary, complexing azo dyes with zinc sulfide significantly improves their lightfastness, outperforming pure azo dyes, zinc ion coordination alone, and copper sulfide complexation. This indicates that complexation structures, especially zinc sulfide complexation, are an effective strategy for optimizing the lightfastness of azo dyes, providing structural design ideas for their application in outdoor and lightfast environments.

[0137] 2. UV-B blocking rate test:

[0138] Weigh 0.01g of each of the following samples: test sample 1, test sample 2, reference sample 5, and reference sample 6. Dissolve them in an appropriate amount of ultrapure water, transfer them to a 100mL volumetric flask, and dilute to the mark with ultrapure water to prepare a 0.1mg / mL solution.

[0139] Using ultrapure water as a reference, a UV-Vis spectrophotometer was used to scan in the 280–320 nm wavelength range, and each sample was tested three times.

[0140] The blocking rate and the wavelength of the absorption peak were calculated by subtracting 10 from the negative power of absorbance. The results are shown in Table 2-2.

[0141] Table 2-2 UV-B blocking rate test

[0142] sample UV-B blocking rate (%) Example 1 81.2±0.7 Example 2 95.8±0.3 Comparative Example 5 79.7±0.7 Comparative Example 6 86.0±0.2

[0143] As shown in Table 2-2, the UV-B blocking rate of Example 2 reached 95.8 ± 0.3%, which was significantly higher than that of Example 1, Comparative Example 5, and Comparative Example 6. Because Example 2 involved a complexation of an azo dye with zinc sulfide, the complexation effect altered the molecular structure, enhancing UV-B absorption and blocking. This indicates that the azo dye-zinc sulfide complexation can significantly improve UV-B blocking performance. Although Example 1 contained a 2-(2-hydroxy-5-sulfonic acid phenyl)benzotriazole structure with some blocking properties, it lacked a complexation structure, resulting in a lower blocking rate than Example 2, demonstrating the role of complexation modification in performance optimization. Comparative Example 5, which replaced zinc sulfate with copper sulfate, had a lower blocking rate than Example 2, indicating that the type of metal ion affects the complexation effect, with zinc sulfide showing greater advantage in improving UV-B blocking rate. Comparative Example 6, without the addition of sodium sulfide and only involving zinc ion coordination, had a lower blocking rate than Example 2, indicating that the complete zinc sulfide complex structure is more crucial for improving the blocking rate, while simple zinc ion coordination has limited effect.

[0144] In summary, complexing azo dyes with zinc sulfide is an effective strategy to improve UV-B blocking efficiency. The type of metal and the integrity of the complex structure affect the performance, providing a structural design reference for the development of high UV-B blocking materials.

[0145] 3. Complexation structure and performance testing:

[0146] Weigh 0.001g of test sample 2, add 10mL of anhydrous ethanol, sonicate at 150W for 5min, drop 1 drop of the diluted solution onto the copper grid of the carbon support film, air dry at room temperature and place it in the TEM sample chamber, randomly select 5 fields of view and measure the particle size of 50 zinc sulfide nanoparticles.

[0147] The average particle size and relative standard deviation were calculated. At the same time, the particle size distribution span was calculated by the ratio of the difference between particle size distributions D90 and D10 to D50. The results are shown in Table 2-3-1.

[0148] Table 2-3-1 Particle Size of Complex Structure and Performance Testing

[0149] Test Project Example 2 Average particle size (nm) 25.2±1.4 Relative standard deviation (%) 2.9 Particle size distribution span 0.44±0.03

[0150] As shown in Table 2-3-1, the azo dye zinc sulfide complex prepared in Example 2 has an average particle size of 25.2 ± 1.4 nm, a relative standard deviation of 2.9%, and a particle size distribution span of 0.44 ± 0.03. After ultrasonic complexation, washing, and drying, the complex exhibits relatively uniform particle size and good dispersibility. This indicates that the preparation process in Example 2 can effectively control the particle size and distribution of zinc sulfide nanoparticles in the complex, providing a microstructural basis for further investigation of the influence of the complex structure on dye performance, and also demonstrating the regulatory role of process parameters on the particle size characteristics of the complex.

[0151] 10 mg of each of the following samples were weighed and pressed into thin slices with a diameter of 10 mm and a thickness of 1 mm. The XPS spectra of Zn 2p, hydroxyl O1s, sulfonic acid O1s, sulfonic acid S2p, and zinc sulfide S2p were tested respectively. The results are shown in Table 2-3-2.

[0152] Table 2-3-2 Binding Energy of Complex Structure and Performance Testing

[0153]

[0154] Note: "-" indicates that the compound is not present.

[0155] As shown in Table 2-3-2, for zinc, the Zn 2p3 / 2 binding energies detected in Example 2 and Comparative Example 6 were 1022.5 eV and 1022.3 eV, respectively, while those in Example 1 were not detected. This indicates that Example 2 and Comparative Example 6 introduced zinc, while Example 1 lacked zinc-related structures. For oxygen, the hydroxyl group O1s binding energies differed among Example 1, Example 2, and Comparative Example 6; the sulfonic acid group O1s binding energies also differed among the three. This reflects that the complexation reaction and simple zinc ion coordination altered the chemical environment surrounding the hydroxyl and sulfonic acid groups, which differed from the oxidative environment of Example 1. For sulfur, the zinc sulfide S2p was detected in Example 2 at 161.8 eV, while those in Example 1 and Comparative Example 6 were not detected. This indicates that the addition of sodium sulfide in Example 2 resulted in the formation of a zinc sulfide structure; the differences in the sulfonic acid group S2p binding energies among the three demonstrate the influence of zinc ions and zinc sulfide on the sulfur chemical environment of the sulfonic acid groups. Example 2 involved ultrasonic complexation with azo dye, zinc sulfate, and sodium sulfide to generate a complex containing Zn and zinc sulfide (S). Binding energy data verified the formation of the zinc sulfide complex structure. Comparative Example 6 used only azo dye and zinc sulfate, without sodium sulfide, therefore no zinc sulfide S2p signal was observed; it only demonstrated the alteration of the oxygen and sulfur chemical environment by zinc ion coordination. Example 1 did not involve zinc-related reactions, and therefore lacked the characteristic binding energies of zinc and zinc sulfide, maintaining the original oxygen and sulfur chemical environment of the azo dye.

[0156] In summary, Example 2 successfully constructed an azo dye-zinc sulfide complex structure, and the introduction of zinc and zinc sulfide significantly altered the chemical environment of oxygen and sulfur. Comparative Example 6 only achieved zinc ion coordination; although it altered the oxygen and sulfur environment, it did not form a zinc sulfide structure, which differs from the structure of Example 2. Example 1 maintained the pure azo dye structure, with no zinc-related effects, and its oxygen and sulfur chemical environments were independent. These structural differences provide a microstructural basis for explaining the differences in performance such as lightfastness and UV-B blocking rate.

[0157] Experimental Example 3

[0158] This experimental example tests the dye utilization rate, light scattering and glare suppression, and fiber binding strength of the test sample from Example 3 and the control samples from Comparative Examples 7-8. The specific steps include:

[0159] 1. Dye utilization rate test:

[0160] Weigh 20 mg of dye, dissolve it in an appropriate amount of ultrapure water, transfer it to a 100 mL volumetric flask, and dilute to the mark with ultrapure water. Transfer 0 mL, 5 mL, 2.5 mL, 1 mL, and 0.5 mL of the solution to 10 mL volumetric flasks respectively, and dilute to the mark with ultrapure water to obtain the standard working solution.

[0161] The production waste liquids of test sample 3, reference sample 7, and reference sample 8 were collected. Among them, test sample 3 and reference sample 8 were waste liquids after papermaking, and reference sample 7 was waste liquids after dipping and coating. The absorbance was measured at 500 nm using an ultraviolet spectrophotometer. Each sample was tested three times.

[0162] A standard curve was plotted with the concentration of the standard working solution on the x-axis and the absorbance on the y-axis. The concentration of the remaining dye in the waste liquid was calculated based on the absorbance of the sample. The dye utilization rate was then calculated based on the ratio of the difference between the total amount of dye added and the amount of remaining dye to the total amount of dye added. The results are shown in Table 3-1.

[0163] Table 3-1 Dye Utilization Rate Test

[0164] sample Dye utilization rate (%) Example 3 (Flower-shaped mesh model) 93.0±0.5 Example 3 (Triangular Mesh Module) 94.8±0.8 Example 3 (Cellular Mesh Model) 91.2±0.8 Comparative Example 7 16.0±0.5 Comparative Example 8 74.3±0.8

[0165] As shown in Table 3-1, the dye utilization rate of the paper prepared by different 3D printed mesh patterns (flowers, triangles, and honeycomb) in Example 3 was 91.2%–94.8%, which was much higher than that of the conventional dip-coating comparative example 7 and the flat mesh comparative example 8, indicating that the integrated microstructure 3D printing process can significantly improve dye utilization. Figure 1 For flower texture, Figure 2 For triangular texture, Figure 3For the honeycomb texture, Example 3 uses a 3D-printed mesh to construct the specific texture described above. During papermaking, the dye and pulp are more fully bonded, reducing waste liquid residue. This is due to the strong hydrophilicity of the sulfonic acid groups in the dye molecules and the ion-dipole interaction formed by the hydroxyl groups in the fibers, which allows the dye to adhere tightly to the grooves and protrusions of the texture. At the same time, the rigid structure of the azo dye-zinc sulfide complex can fill the gaps in the texture, forming a dense bonding layer and preventing the dye from being lost with moisture penetration.

[0166] The triangular mesh had the highest utilization rate of 94.8%, likely due to its staggered structure formed by an angle of 60°±1° and a tooth depth of 0.3mm±0.05mm, which increased the contact area with the dye. Combined with the coordination of zinc ions in the dye with the fibers, this enhanced dye fixation. The honeycomb and flower meshes, due to differences in pore size and depth, had slightly lower dye binding efficiency, but the complex structure of the dye still effectively reduced penetration, resulting in a utilization rate far superior to the comparative example without a 3D structure. In Comparative Example 7, the paper was first made and then dip-coated. The paper surface and internal structure were dense, making it difficult for the sulfonic acid groups of the dye to penetrate into the fiber gaps. Furthermore, the lack of 3D texture anchoring resulted in a large amount of dye failing to bind, leaving residual waste liquid. The utilization rate was only 16.0%, highlighting the serious dye waste in traditional processes. Comparative Example 8 uses a flat mesh instead of a 3D mesh. Although it belongs to the same integrated process as Example 3, the flat mesh has no specific microstructure. The dye cannot achieve efficient fixation through the physical constraint and chemical bonding of the texture gaps. The bonding efficiency is low, which proves that the synergy between the 3D microstructure and the dye properties is the key design to improve the dye utilization rate.

[0167] In summary, the integrated microstructure 3D printing process significantly improves dye utilization by constructing specific textures such as flowers, triangles, and honeycombs, combined with the hydrophilicity of dye sulfonic acid groups and the rigid structure of the complex. This solves the dye waste problem associated with traditional dip coating and processes without specific microstructures. Among these, the triangular mesh model performed best, providing a new approach to optimizing paper dyeing processes by linking structure and performance.

[0168] 2. Light scattering and glare suppression test:

[0169] Take the paper of the three 3D mesh models of Example 3, control 7, and control 8, and cut them into 5cm×5cm samples, with 3 parallel samples for each sample;

[0170] A gloss meter with a 60° incident angle and a D65 light source was used to test each sample at 5 different locations. The glare intensity was recorded and the average value was calculated. The results are shown in Table 3-2.

[0171] Table 3-2 Light Scattering and Glare Suppression Tests

[0172] sample Glare intensity Example 3 (Flower-shaped mesh model) 18.5±0.2 Example 3 (Triangular Mesh Module) 15.2±0.3 Example 3 (Cellular Mesh Model) 12.8±0.2 Comparative Example 7 35.5±0.3 Comparative Example 8 28.4±0.3

[0173] As can be seen from Table 3-2, the glare intensity of the 3D printed microstructure paper (flower, triangle, honeycomb mesh) in Example 3 is significantly lower than that in Comparative Example 7 and Comparative Example 8, indicating that 3D printed microstructures can effectively suppress glare, and the glare suppression effect of different microstructures (flower, triangle, honeycomb) varies.

[0174] In Example 3, the honeycomb mesh paper exhibited the lowest glare intensity of 12.8 ± 0.2. Its porous structure, formed by pores with a diameter of 2 mm ± 0.05 mm and a depth of 0.5 mm ± 0.05 mm, combined with the uniform distribution of the dye-zinc sulfide complex, caused the light intensity to decrease after multiple scattering and refractions within the texture. Simultaneously, the sulfonic acid groups in the dye molecules were tightly bound to the fibers, preventing uneven local concentrations caused by dye penetration and ensuring the stability of the texture's light scattering. The triangular mesh with an angle of 60° ± 1° and a tooth depth of 0.3 mm ± 0.05 mm, with its serrated structure and strong dye adhesion, ensured that light reflected from the toothed surface was uniformly absorbed by the dye, resulting in a glare intensity of 15.2 ± 0.3, superior to the flower-shaped mesh. The flower mesh with petal diameter of 3mm±0.05mm and depth of 0.4mm±0.05mm has a curved surface structure that has a weaker light-guiding effect. However, the complex structure of the dye reduces local light leakage caused by penetration, and the glare suppression effect is still much better than that of the sample without specific microstructure.

[0175] Comparative Example 7 involved papermaking followed by impregnation and coating. The dye distribution on the paper surface was uneven, and the lack of 3D texture support made it easy for light to be reflected by the surface mirrors, resulting in strong glare with an intensity of 35.5±0.3. Comparative Example 8 used a flat screen instead of a 3D screen. Although the dye and fiber bonded better than the traditional process, there was no specific microstructure to guide light scattering, and the dye was prone to slight penetration due to the lack of texture constraints, leading to enhanced local reflection and a glare intensity of 28.4±0.3. This demonstrates that the synergy between the 3D microstructure and the dye's anti-penetration properties is the core design for glare suppression.

[0176] In summary, the integrated microstructure 3D printing process effectively reduces paper glare intensity by constructing textures such as flowers, triangles, and honeycombs, combined with the strong adhesion and impermeability of dyes, thus solving the glare problem of traditional dip coating and processes without specific microstructures. Among these, the honeycomb mesh model performs best due to its structural characteristics, providing a design approach for optimizing the optical properties of paper and suppressing glare.

[0177] 3. Fiber bonding strength test:

[0178] Take the three 3D mesh models from Example 3 and control sample 8, cut them into strips of 150mm × 25mm, and make each sample 3 parallel;

[0179] Use double-sided tape to fix one end of the paper strip to the upper clamp of the universal testing machine and the other end to the lower clamp. The test area is the middle 50mm. Test at a rate of 10mm / min and record the maximum force value during the peeling process.

[0180] The peel strength was calculated by the ratio of the maximum force during the peeling process to the width of the sample. The results are shown in Table 3-3.

[0181] Table 3-3 Fiber Bonding Strength Test

[0182] sample Peel strength (N / m) Example 3 (Flower-shaped mesh model) 128±4 Example 3 (Triangular Mesh Model) 140±4 Example 3 (Cellular Mesh Model) 132±4 Comparative Example 8 84±4

[0183] As can be seen from Table 3-3, the paper prepared by 3D printing different mesh patterns (flower, triangle, honeycomb) in Example 3 has a higher peel strength than that of Comparative Example 8, indicating that 3D printed microstructures can enhance the bonding force of paper fibers, and different microstructures have different effects on improving the bonding force.

[0184] In Example 3, the triangular mesh paper exhibited the highest peel strength at 140±4 N / m. Its interlaced texture, formed by an angle of 60°±1° and a tooth depth of 0.3mm±0.05mm, ensured the fibers were tightly interwoven along the tooth surface during papermaking and dewatering. Simultaneously, the sulfonic acid groups in the dye molecules formed silicon-oxygen bonds with the fibers via γ-aminopropyltriethoxysilane, and the azo dye-zinc sulfide complex filled the gaps between the teeth, creating rigid support and further strengthening the fiber bond. While the peel strength of the honeycomb and flower meshes was slightly lower than that of the triangular mesh, the 3D microstructure increased the fiber contact area. Combined with the dye's anti-permeation properties—the complex blocking the permeation channels between fibers—the fiber bonding strength remained significantly higher than that of the flat mesh sample.

[0185] Comparative Example 8 uses a flat mesh instead of a 3D mesh, and the peel strength is 84±4 N / m. Because the flat mesh lacks specific microstructure to guide the fiber arrangement and interweaving, and the dye lacks texture constraint, it is prone to slight penetration and cannot form a uniform bonding layer, resulting in loose fiber bonding. This proves that the strong bonding and anti-penetration characteristics of the 3D microstructure and dye are the key design to improve fiber bonding strength.

[0186] In summary, the integrated microstructure 3D printing process significantly enhances the bonding strength of paper fibers by constructing textures such as flowers, triangles, and honeycombs, combined with the bridging effect of dye sulfonic acid groups and the rigid support of complexes. This solves the problem of loose fiber bonding in processes without specific microstructures. Among these, the triangular mesh pattern exhibits the best performance due to its structural characteristics, providing a design approach that correlates structure and bonding strength for optimizing the mechanical properties of paper.

[0187] Experiment Example 4

[0188] This experimental example tested the mechanical properties, protective properties, writing and printing compatibility, and interlayer bonding strength of the test sample from Example 4 and the control samples from Comparative Examples 9-12. The specific steps included:

[0189] 1. Mechanical property testing:

[0190] Test sample 4 and reference samples 9-12, each 150mm×15mm in dry condition, were placed in a universal testing machine and stretched at a rate of 50mm / min until fracture. The maximum load was recorded. The tensile strength in dry condition was calculated by the ratio of the maximum load to the product of the sample width and thickness. The thickness was measured using a thickness gauge.

[0191] Using an MIT folding endurance tester with a tension of 9.8N, the number of folds until breakage was recorded, which is the number of double folds.

[0192] Take samples from the same batch after the tensile strength test in the dry state, soak them in distilled water at 25℃ for 24 hours, take them out and dry the surface moisture, and immediately test the wet tensile strength. Calculate the wet strength retention rate by the ratio of wet tensile strength to dry tensile strength. Repeat the test 3 times for each sample. The results are shown in Table 4-1.

[0193] Table 4-1 Mechanical Property Tests

[0194]

[0195] As can be seen from Table 4-1, the three-layer protective paper (flower, triangle, honeycomb texture) of Example 4 is superior to the single-layer comparative example 9, the comparative example 10 without the bottom layer, the comparative example 11 without the top layer, and the comparative example 12 with the traditional top layer in terms of dry tensile strength, number of folds, and wet strength retention rate. This shows that the three-layer structure design and 3D texture work together to improve the mechanical properties of the paper.

[0196] Comparative Example 9 exhibited the worst mechanical properties, with a tensile strength of 15.6–17.8 MPa, a bifolding count of 52–54, and a wet strength retention rate of 20.1–29.6%. This was due to the lack of underlying support and surface protection, as well as the absence of synergistic effects between the dye and texture. The sulfonic acid groups in the dye could not form stable hydrogen bonds through the underlying fiber network, and the azo dye-zinc sulfide complex was also unable to fill the fiber gaps, resulting in loose fiber bonding and easy breakage. Comparative Examples 10 and 11 showed weaker performance than Example 4, demonstrating the crucial role of underlying reinforcement and surface protection in mechanical properties. Comparative Example 12 used epoxy resin instead of the copolymer fiber membrane. However, due to the lack of affinity between the epoxy resin and the dye complex, it could not synergistically improve the bonding force with the texture, and its performance was still inferior to Example 4.

[0197] In Example 4, the honeycomb textured paper exhibited the best performance, with a tensile strength of 40.1 MPa, a double-fold count of 305, and a wet strength retention rate of 71.2%. The triangular texture was second best, while the floral texture was slightly weaker. This is because the porous structure of the honeycomb texture and the rigid structure of the dye complex form an interlocking effect, with the complex filling the gaps between the pores and enhancing the friction between fibers. The interlaced structure of the triangular texture synergistically with the hydrophilic effect of the sulfonic acid groups in the dye, promoting tight fiber weaving. Although the curved structure of the floral texture has a slightly smaller contact area, the dye's anti-permeation properties still improve the wet strength retention rate. The synergy between the 3D texture and the dye alters the fiber weaving pattern, increases stress dispersion paths, and, combined with the three-layer structure, further strengthens the mechanical properties.

[0198] 2. Protection performance test:

[0199] The test sample 4 and reference samples 9-12 were fixed on the sample holder of the UV-Vis spectrophotometer. Using air as a reference, each sample was tested three times. The transmittance of blue light in the 380-500nm and UV-B 280-320nm bands was scanned, and the initial blocking rate was calculated.

[0200] The samples were placed in a lightfast aging chamber and irradiated with ultraviolet and blue light for 100 hours. The aging barrier rate was then tested. The attenuation rate was calculated by the ratio of the difference between the initial barrier rate and the aging barrier rate to the initial barrier rate. The results are shown in Table 4-2.

[0201] Table 4-2 Protective Performance Test

[0202]

[0203] As can be seen from Table 4-2, the three-layer protective paper (flower, triangle, honeycomb texture) of Example 4 has a significantly lower blue light and UV-B attenuation rate than Comparative Examples 9-12. This indicates that the three-layer structure design and 3D texture work together to improve the paper's resistance to light attenuation and effectively maintain the stability of the barrier rate.

[0204] Comparative Example 9 exhibited the highest degradation rate because it lacked a bottom or surface layer for protection. The dye in the functional layer was directly exposed to the photoaging environment, lacking the scattering buffer provided by the 3D texture. Furthermore, the dye did not form a stable complex structure, making the azo bonds susceptible to UV-induced breakage, resulting in a rapid decrease in blocking efficiency. Comparative Examples 10 and 11 showed higher degradation rates than Example 4. Due to the absence of a bottom or surface layer, the dye's protection against photodegradation was insufficient. The nanocellulose in the bottom layer could absorb some UV radiation, and the copolymer fiber film on the surface could reflect strong light. The 3D texture, through its specific structure, dispersed light into multiple paths, reducing the light intensity received by the functional layer. Combined with the electron cloud interaction between zinc ions and azo groups in the dye, this increased the excited state energy level, further inhibiting photodegradation.

[0205] In Example 4, the honeycomb textured paper exhibited the lowest attenuation rate. This is because its labyrinthine scattering structure, formed by a pore size of 2mm ± 0.05mm and a depth of 0.5mm ± 0.05mm, synergistically reduces light damage to the functional layer due to the absorption and scattering effects of the dye-zinc sulfide complex. The serrated structure of the triangular textured paper enhances light reflection, and combined with the dye's lightfastness, its attenuation rate is the second lowest. The curved structure of the flower textured paper scatters light slightly less, but the dye's anti-photodegradation properties still maintain a low attenuation rate. Comparative Example 12, which uses epoxy resin instead of the copolymer fiber membrane, suffers from poor compatibility between the surface layer and the dye, failing to synergistically disperse light through the texture. Therefore, its attenuation rate is still higher than in Example 4, demonstrating the synergistic advantage of the 3D texture and the dye's anti-photoaging properties.

[0206] 3. Writing and printing compatibility test:

[0207] A 2cm × 2cm black area was inkjet printed on the surface of test sample 4, reference sample 10, and reference sample 12, and dried at 60℃ for 10 min.

[0208] A 2cm × 2cm black block was laser-printed on the surface of test sample 4, reference sample 10, and reference sample 12, and then cooled to room temperature.

[0209] Completely adhere 2cm wide tape to the printed area, peel it off quickly at a 45° angle, and record the area of ​​ink layer loss. Repeat the test 3 times for each sample. Calculate the loss rate by the ratio of the loss area to the printed area.

[0210] Write continuously on the sample surface with a 0.5mm steel-tipped writing pen for a total length of 100m. Record the number of ink breaks and wrinkling. Repeat the test 3 times for each sample. The results are shown in Table 4-3.

[0211] Table 4-3 Writing and Printing Compatibility Test

[0212]

[0213] As can be seen from Table 4-3, the three-layer protective paper (flower, triangle, honeycomb texture) of Example 4 is superior to Comparative Example 10 and Comparative Example 12 in terms of writing and printing adaptability, indicating that the three-layer structure design and 3D texture work together to ensure the paper's writing and printing adaptability.

[0214] Comparative Example 10 exhibited a higher rate of ink shedding than Example 4, and also showed ink breaks and slight wrinkling. Due to the lack of underlying reinforcement, the paper fibers were easily deformed under writing pressure. Furthermore, the dye in the 3D texture, lacking underlying cross-linking support, was prone to localized penetration as it moved with the fibers, resulting in decreased surface smoothness and weakened ink adhesion. Comparative Example 12 showed an extremely high rate of ink shedding, numerous instances of ink breaks, and severe wrinkling. This was due to the significant polarity difference between the epoxy resin surface layer and the dye, and the absence of a microscopic adaptation structure in the 3D texture, preventing effective ink adhesion. Simultaneously, the dye, lacking complexation protection, easily penetrated to the surface, disrupting writing smoothness.

[0215] In Example 4, the honeycomb textured paper exhibited the lowest ink shedding rate. This is because the micron-level grooves formed by its pore size of 2mm ± 0.05mm and depth of 0.5mm ± 0.05mm can lock the ink layer through a mechanical anchoring effect. Furthermore, the rigid structure of the dye-zinc sulfide complex prevents uneven surface composition caused by penetration. Combined with the surface micro-roughening treatment, this significantly improves compatibility. The interlaced structure of the triangular texture ensures more uniform dye distribution, stable surface tension, and zero ink breakage. Although the curved structure of the flower texture has a slightly smaller contact area, the dye's anti-penetration properties ensure no localized light leakage or deformation, and no wrinkling. The synergistic optimization of the 3D texture and dye enhances the surface microstructure and chemical stability, guaranteeing compatibility for writing and printing.

[0216] 4. Interlayer bonding strength test:

[0217] Test specimen 4, reference specimen 10, and reference specimen 12, each measuring 100mm × 25mm, were peeled 50mm apart along the length of the bottom layer and the middle layer, and the middle layer and the top layer, using double-sided tape. They were then fixed to the upper and lower clamps of the peel tester and peeled at a rate of 10mm / min. The maximum peel force was recorded.

[0218] The peel strength between the bottom layer and the middle layer, and between the middle layer and the top layer, was calculated by the ratio of the maximum peel force to the width of the sample. The results are shown in Table 4-4.

[0219] Table 4-4 Interlayer Bond Strength Test

[0220]

[0221] As can be seen from Table 4-4, the peel strength between the bottom layer and the middle layer, and between the middle layer and the top layer of the three-layer protective paper in Example 4 is significantly higher than that of Comparative Example 10 and Comparative Example 12, indicating that the three-layer structure design and 3D texture synergistically enhance the interlayer bonding of the paper.

[0222] Comparative Example 10, lacking a bottom layer, has no data on the bonding between the bottom and intermediate layers. The peel strength between the intermediate and surface layers is low because it lacks the nanocellulose and carboxymethyl chitosan composite layer of the bottom layer. This layer can bond with the dye in the intermediate layer through hydrogen bonds. While the grooved structure of the 3D texture could increase the contact area between the bottom and intermediate layers, the absence of the bottom layer means the dye lacks an anchoring base, resulting in inherently weak interlayer bonding. Comparative Example 12 also exhibits low interlayer peel strength due to poor dye compatibility between the epoxy resin surface and intermediate layers, and the absence of the interlocking convex-concave structure of the 3D texture, which prevents physical enhancement of bonding. In contrast, the fluorinated groups in the copolymer fiber membrane of Example 4 can form chemical bonds with the γ-aminopropyltriethoxysilane coupling agent in the dye, thus improving bonding strength in conjunction with the texture.

[0223] In Example 4, the honeycomb textured paper exhibited the highest interlayer peel strength. Its pore size of 2mm ± 0.05mm and depth of 0.5mm ± 0.05mm significantly increased the interlayer contact area. The dye-zinc sulfide complex filled the texture gaps, forming mechanical rivets, and the silane coupling agent bridged the layers through silicon-oxygen bonds, strengthening the chemical bond. The interlaced structure of the triangular texture promoted interlayer diffusion, and combined with the complexing rigidity of the dye, its peel strength was second highest. The curved structure of the flower texture made the interlayer contact more uniform, and the sulfonic acid groups of the dye formed dense hydrogen bonds with the underlying hydroxyl groups, resulting in a peel strength still significantly higher than the comparative example. The synergy between the 3D texture and the dye—physical interlocking and chemical bonding—significantly improved the interlayer adhesion.

[0224] In summary, Example 4, through a three-layer structure consisting of a bottom layer, a functional layer, and a copolymer fiber membrane surface layer, and a 3D microtexture design, combined with the hydrophilicity of the sulfonic acid groups of the dye and the rigidity and photodegradation resistance of the azo dye-zinc sulfide complex, solves the problems of single-layer, missing-layer, and poor protective performance of traditional surface paper, providing a high-performance solution for myopia protection paper.

[0225] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Equal modifications and variations made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the overall concept of the present invention, shall still fall within the scope of the present invention.

Claims

1. A method for preparing a yellow light-absorbing dye for myopia prevention, characterized in that: A method for preparing a yellow light-absorbing dye for myopia prevention includes the following steps: S001, p-nitroaniline is added to dilute sulfuric acid for dissolution treatment, sodium nitrite solution is slowly added dropwise, and the mixture is stirred to obtain a diazonium salt solution. The concentration of dilute sulfuric acid is 20%, the dissolution treatment conditions are 3 ℃, 300 rpm / min until completely dissolved, the molar ratio of sodium nitrite to p-nitroaniline is 1.05:1, and the stirring treatment conditions are 3 ℃, 300 rpm / min, 60 min. S002, 2-(2-hydroxy-5-sulfonylphenyl)benzotriazole was added to a sodium carbonate solution and dissolved to obtain a coupling component solution. The concentration of the sodium carbonate solution was 50 mg / mL, and the concentration of 2-(2-hydroxy-5-sulfonylphenyl)benzotriazole in the coupling component solution was 105 mg / mL. The dissolution conditions were 8 ℃, 300 rpm / min, and pH value of 8~9. S003, the diazonium salt solution was slowly added dropwise to the coupling component solution for coupling reaction treatment. Sodium chloride was added for salting out. After filtration, washing, recrystallization, and vacuum drying, the azo dye was obtained. The molar ratio of p-nitroaniline in the diazonium salt solution to 2-(2-hydroxy-5-sulfonylphenyl)benzotriazole in the coupling component solution was 1:

1. The coupling reaction conditions were 8 ℃, 300 rpm / min, pH 8~9, and 1.5 h. The mass ratio of sodium chloride to p-nitroaniline was 6:

1. S004, the azo dye was added to ultrapure water and stirred, then zinc sulfate solution was added and ultrasonically complexed, followed by the dropwise addition of sodium sulfide solution. The mixture was then filtered, washed, and dried to obtain the azo dye-zinc sulfide complex, denoted as the dye. The solid-liquid ratio of the azo dye to ultrapure water was 1:10, the concentration of the zinc sulfate solution was 0.1 mol / L, the concentration of the sodium sulfide solution was 0.05 mol / L, and the amount of sodium sulfide solution added was 20% of the total volume of the reaction system.

2. A method for preparing myopia protection paper, characterized in that: To achieve myopia protection, myopia-protective paper can be produced through multi-layer composite processing and 3D printing texture optimization, specifically including the following steps: S101, the bottom composite solution is uniformly coated on the bottom layer of the base paper, and after drying, the nano silica dispersion is sprayed onto the paper surface and dried to obtain the first-grade treated paper. S102, the dye prepared by the method described in claim 1 is added to the dispersion solution, and micro-jet homogenization, high shear dispersion and ultrasonic dispersion are performed in sequence. A silane coupling agent is added and stirred to react, thus obtaining the pretreated dye. S103, the pretreated dye is coated on the surface of the primary treated paper, dried, immersed in crosslinking agent, reacted, washed and dried, and this step is repeated once to obtain the secondary treated paper. S104 involves hot-pressing the copolymer fiber film onto the surface of the secondary-treated paper, followed by fumigation and surface micro-roughening treatment to obtain myopia protection paper.

3. The method for preparing myopia protection paper according to claim 2, characterized in that: In step S101, the preparation of the basic paper involves adding pulp to ultrapure water, stirring, adding dye and γ-aminopropyltriethoxysilane, mixing, and then performing 3D printing of a mesh, vacuum papermaking, and drying to obtain the basic paper with a textured structure. The mass ratio of dye to pulp is 1:50, the amount of γ-aminopropyltriethoxysilane added is 0.2%, and the 3D printing meshes used are flowers, triangles, and honeycomb. The mass fraction of silica in the nano silica dispersion is 3%, and the bottom composite solution is composed of nanocellulose suspension and carboxymethyl chitosan, wherein the mass ratio of nanocellulose suspension to carboxymethyl chitosan is 3:

1.

4. The method for preparing myopia protection paper according to claim 2, characterized in that: In step S102, the dispersion solution is an aqueous solution of sodium hexametaphosphate, and the amount used is 1% of the dye mass. The silane coupling agent is γ-aminopropyltriethoxysilane, and the amount used is 2% of the dye mass.

5. The method for preparing myopia protection paper according to claim 2, characterized in that: In step S103, the drying conditions are 40 °C for 15 min and 60 °C for 30 min, and the crosslinking agent is 1% glutaraldehyde.

6. The method for preparing myopia protection paper according to claim 2, characterized in that: In step S104, the hot pressing treatment involves first hot pressing at 50 ℃ and 0.5 MPa for 15 s, then increasing the temperature to 60 ℃ and hot pressing at 0.5 MPa for 15 s, and finally increasing the temperature to 70 ℃ and hot pressing at 0.5 MPa for 15 s. Fumigation is performed using perfluorooctyltriethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane in a mass ratio of 7:

3. Surface micro-roughening is performed using a plasma etching instrument with a power of 100 W, an internal pressure of 5 Pa, an oxygen flow rate of 10 sccm, and a 30°C setting. The copolymer fiber membrane is composed of methacrylic acid, 2,2,2-trifluoroethyl acrylate, additives and hydroxyethyl cellulose. The mass ratio of methacrylic acid to 2,2,2-trifluoroethyl acrylate is 3:2, the concentration of 2,2,2-trifluoroethyl acrylate is 35%, the additives are composed of 5 wt% photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 12 wt% polyvinylpyrrolidone, and the amount of hydroxyethyl cellulose added is 5% of the total system mass.

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