Rare earth modified titanium dioxide photocatalyst, optical diffusion plate sterilization coating liquid and preparation method of optical diffusion plate sterilization coating liquid

Abstract

The invention relates to a rare earth modified titanium dioxide photocatalyst, an optical diffusion plate sterilization coating liquid and a preparation method thereof, the rare earth modified titanium dioxide is nano titanium dioxide with an anatase crystal structure, the crystal lattice of the rare earth modified titanium dioxide is doped with rare earth elements, and the rare earth elements are selected from one or more of lanthanum, cerium, samarium, europium, neodymium and yttrium. According to the application, the rare earth modified titanium dioxide is added into the sterilization coating liquid, so that the prepared sterilization coating accidentally obtains efficient photocatalytic sterilization activity and photocatalytic degradation resistance under the indoor visible light condition.

Description

Technical Field

[0001] This application relates to the field of bactericidal coating liquid preparation technology, and in particular to a rare earth modified titanium dioxide photocatalyst, an optical diffuser plate bactericidal coating liquid, and a preparation method thereof. Background Technology

[0002] As a core optical component in LCD display backlight modules and LED lighting equipment, the surface cleanliness and sterilization performance of optical diffuser plates directly affect the user experience and public health safety of end products. In public places such as hospitals, schools, and shopping malls, the surfaces of display devices and touch screens can easily become breeding grounds for bacteria and viruses. Therefore, inhibiting the survival and spread of microorganisms on the surface of optical diffuser plates is of great practical significance. Photocatalytic sterilization technology, especially based on nano-titanium dioxide, is one of the ideal ways to solve the above problems. Its principle is that under photoexcitation, titanium dioxide generates highly oxidizing photogenerated holes and reactive oxygen species, which can efficiently decompose microbial organisms and achieve sterilization. However, traditional photocatalytic sterilization technology faces two major technological challenges when applied to optical diffusers: Firstly, the substrates of optical diffusion plates are mostly engineering plastics such as polycarbonate and polymethyl methacrylate. These substrates have low surface energy and poor compatibility with inorganic nano-titanium dioxide, making it difficult for traditional coating liquids to wet and spread on their surface, and easily causing coating defects such as pinholes and fisheyes. At the same time, the adhesion between the coating and the substrate is weak, and during use, it is easy to crack, powder or peel off due to thermal expansion and contraction or external wiping. Not only does it lose its bactericidal function, but the peeled coating fragments can also cause light blocking and scattering, forming dark spots or bright spots, affecting optical performance. Secondly, while titanium dioxide photocatalytically decomposes microorganisms, its strong oxidizing properties indiscriminately attack the organic resins in the coating, causing the coating itself to undergo photocatalytic degradation, manifested as polymer chain breakage, yellowing, stickiness, and loss of mechanical properties, which seriously affects the long-term stability of the bactericidal coating. Therefore, developing a highly efficient photocatalytic bactericidal coating liquid that can solve the problem of poor stability of bactericidal coatings has become an urgent need in this field. Summary of the Invention

[0003] In order to make the bactericidal coating liquid have both high efficiency in photocatalysis and coating stability, this application provides a rare earth modified titanium dioxide photocatalyst, an optical diffuser plate bactericidal coating liquid and its preparation method.

[0004] In a first aspect, this application provides a rare earth-modified titanium dioxide photocatalyst, employing the following technical solution: A rare earth modified titanium dioxide photocatalyst, wherein the rare earth modified titanium dioxide is anatase-type nano-titanium dioxide with rare earth elements doped in its crystal lattice, wherein the rare earth elements are selected from one or more of lanthanum, cerium, samarium, europium, neodymium, and yttrium.

[0005] Preferably, the above-mentioned rare earth modified titanium dioxide is cerium and lanthanum co-doped nano-titanium dioxide.

[0006] Preferably, the preparation steps of the above-mentioned cerium and lanthanum co-doped nano-titanium dioxide are as follows: S1-1. Dissolve tetrabutyl titanate in anhydrous ethanol, denoted as solution A; dissolve cerium nitrate hexahydrate and lanthanum nitrate hexahydrate in deionized water, denoted as solution B; add solution B to solution A, adjust the pH of the mixture to 7.0-8.0, stir and mix, and then perform hydrothermal reaction. Post-treatment yields cerium and lanthanum co-doped titanium dioxide precursor. S2-1. The cerium and lanthanum co-doped titanium dioxide precursor obtained in step S1-1 is calcined at 400-500°C in air atmosphere to obtain cerium and lanthanum co-doped nano-titanium dioxide.

[0007] Secondly, this application provides a bactericidal coating liquid for an optical diffusion plate, employing the following technical solution: An optical diffusion plate bactericidal coating liquid comprises the following components by weight percentage: 1.5-2.0% rare earth modified titanium dioxide photocatalyst, 1.2-1.7% film-forming resin, 1.2-1.8% dispersant, 0.5-0.8% wetting agent, 0.3-0.5% defoamer, and 90-96% deionized water; wherein the rare earth modified titanium dioxide is anatase-type nano-titanium dioxide with rare earth elements doped in its crystal lattice, the rare earth elements being selected from one or more of lanthanum, cerium, samarium, europium, neodymium, and yttrium.

[0008] The inventors discovered that adding rare earth-modified titanium dioxide to the bactericidal coating solution can enable the prepared bactericidal coating to have highly efficient photocatalytic bactericidal activity and resistance to photocatalytic degradation under indoor visible light conditions, thereby improving its long-term stability.

[0009] Specifically, titanium dioxide is a wide bandgap semiconductor that can only be excited by high-energy ultraviolet light. This application dops rare earth ions (such as lanthanum, cerium, samarium, europium, neodymium, and yttrium) into its crystal lattice, so that the 4f electron orbitals of rare earth elements form new energy levels between the valence band and conduction band of titanium dioxide. This allows lower-energy visible light photons to excite electrons to the conduction band, thereby achieving the effect of visible light-excited bactericidal activity.

[0010] The advantage of visible light photocatalytic sterilization is that, unlike ordinary titanium dioxide sterilization coating liquid which can only be activated under ultraviolet light, rare earth-doped titanium dioxide can be activated in the visible light wavelength range of 400-700nm, and continuous photocatalytic sterilization can be achieved directly using sunlight or ordinary LED lighting.

[0011] The photocatalytic degradation of the coating is mainly caused by highly active photogenerated holes attacking the molecular chains of organic resins. However, the rare earth-modified titanium dioxide used in this application improves the quantum efficiency, and its rare earth ions can capture photogenerated electrons, thereby significantly delaying the recombination of photogenerated electrons and holes and effectively separating photogenerated electrons and holes. This allows photogenerated holes to react rapidly with water or hydroxide ions adsorbed on the surface of titanium dioxide at the moment of generation, generating active oxygen. Active oxygen preferentially attacks bacteria close to the surface of titanium dioxide, rather than attacking the resin matrix that constitutes the coating framework, thereby greatly improving the bactericidal efficiency and anti-photocatalytic degradation ability of the bactericidal coating.

[0012] Furthermore, the inventors discovered that using cerium and lanthanum co-doped nano-titanium dioxide obtained in the above steps as a catalyst for the bactericidal coating liquid can enable the bactericidal coating to synergistically possess both highly efficient bactericidal properties and excellent optical performance.

[0013] Specifically, the cerium redox pair (Ce 3 ⁺ / Ce 4 Lanthanum not only captures electrons but also regulates hole concentration and reactivity to some extent. This buffering effect makes the photocatalytic reaction more controllable and stable, preventing the instantaneous generation of excessively high hole concentrations from attacking the adjacent resin matrix, thereby slowing down the photodegradation rate of the coating and extending its service life. Furthermore, the incorporation of lanthanum effectively inhibits the growth of titanium dioxide grains during high-temperature calcination, resulting in smaller, more narrowly distributed nanoparticles. According to Rayleigh scattering law, when the particle size is much smaller than the wavelength of light, the scattering effect is greatly reduced. Smaller nanoparticles mean less scattering of visible light, effectively ensuring the coating's high transmittance and reducing the risk of increased haze or image blurring caused by the introduction of functional particles.

[0014] This application incorporates two rare earth elements, cerium and lanthanum, into the crystal lattice of nano-titanium dioxide, thereby modifying the nano-titanium dioxide with these two rare earth elements. This results in a bactericidal coating with highly efficient bactericidal properties and excellent optical properties when preparing a bactericidal coating solution.

[0015] In one specific feasible embodiment, the above-mentioned dispersant is a polyether-b-poly(acrylate-co-silane) block copolymer, and its preparation steps are as follows: S1-2. Polyethylene glycol monomethyl ether, RAFT reagent and 4-dimethylaminopyridine are dissolved in dichloromethane, nitrogen gas is replaced, and the mixture is cooled to 0-5°C in an ice-water bath. A dichloromethane solution of N,N'-dicyclohexylcarbodiimide is added, and the mixture is heated to room temperature and stirred to react. The reaction is then post-treated to obtain the macromolecular RAFT reagent. S2-2, Dissolve the macromolecular RAFT reagent, acrylic acid, 3-(trimethoxysilyl)propyl-2-methyl-2-acrylate, and initiator obtained in step S1-2 in 1,4-dioxane, replace with nitrogen, heat to 65-75°C for polymerization, and then perform post-treatment to obtain polyether-b-poly(acrylate-co-silane) block copolymer.

[0016] The inventors discovered that the polyether-b-poly(acrylate-co-silane) block copolymer prepared by the above steps can significantly improve the adhesion and dispersion stability of the bactericidal coating when used as a dispersant for rare earth modified bactericidal coating liquid. Specifically, the polyether segments in the polyether-b-poly(acrylate-co-silane) block copolymer form a solvation layer in the aqueous phase. The steric hindrance generated by this layer can prevent van der Waals attraction between rare earth modified titanium dioxide particles, keeping the rare earth modified titanium dioxide particles in a monodisperse state. Meanwhile, the carboxyl groups on the polyacrylate segments are deprotonated in a weakly alkaline environment, which can form coordination bonds with the rare earth ions of the rare earth modified titanium dioxide particles, thereby anchoring the polyether-b-poly(acrylate-co-silane) block copolymer to the surface of the rare earth titanium dioxide particles. During curing, the silane segments may react with the hydroxyl groups on the substrate surface to undergo condensation, and can also self-crosslink to form a three-dimensional network, making the dispersant itself part of the cured layer. This stabilizes and uniformly anchors the rare earth titanium dioxide in the coating layer, effectively improving the adhesion, stability, and photocatalytic properties of the bactericidal coating, and achieving highly efficient sterilization.

[0017] This application uses polyether-b-poly(acrylate-co-silane) block copolymer as a dispersant in rare earth modified bactericidal coating liquid, which can simultaneously achieve three major functions: particle dispersion, anchoring functional particles, and bridging the substrate. It bonds the originally incompatible rare earth modified titanium dioxide, film-forming resin, and plastic substrate into a strong whole, further improving the adhesion and dispersion stability of the bactericidal coating, thereby improving the long-term stability of the bactericidal coating.

[0018] In one specific feasible implementation, nano-silica sol is also included.

[0019] The refractive index of nano-silica lies between that of the film-forming resin and air, which helps reduce light scattering loss on the coating surface, thereby improving the light transmittance of the bactericidal coating. Furthermore, during the mixing and preparation of the bactericidal coating solution, the nanoparticles of silica fill the pores of the resin network, significantly improving the density, hardness, and wear resistance of the bactericidal coating. Moreover, the cross-linking of nano-silica with the silane portion of the polyether-b-poly(acrylate-co-silane) block copolymer forms a hybrid network, which effectively resists the attack of reactive oxygen species generated by photocatalysis on the resin matrix, thus enhancing the stability of the bactericidal coating.

[0020] In one specific implementation, the film-forming resin is an aqueous acrylic resin.

[0021] By adopting the above technical solution, water-based acrylic resin was selected as the film-forming resin because of its high transparency, resulting in minimal light transmittance loss after coating, which matches the high light transmittance requirements of optical diffusion plates. Furthermore, the water-based acrylic resin uses water as a diluent and has extremely low volatile organic compound content, meeting environmental protection requirements. It is also easy to apply, has good leveling properties, and readily forms a uniform film.

[0022] The carboxyl groups in the molecular structure of waterborne acrylic resin can form hydrogen bonds with the carboxyl groups and ether bonds on the polyether-b-poly(acrylate-co-silane) block copolymer. During the drying and curing of the coating, the silane groups at the ends of the polyether-b-poly(acrylate-co-silane) block copolymer hydrolyze to generate silanol groups. The silanol groups can react with the hydroxyl groups of the substrate and also bond with the active groups on the molecular chain of the waterborne acrylic resin, establishing a stable and highly adherent three-dimensional network structure on the substrate surface. This greatly enhances the cohesive strength and adhesion of the bactericidal coating to the substrate, thus solving the problem of easy peeling of the coating.

[0023] In one specific feasible implementation, the aforementioned wetting agent is a perfluoropolyether modified wetting agent.

[0024] By adopting the above technical solution, perfluoropolyether exhibits extremely low surface tension, which significantly reduces the surface tension of the bactericidal coating solution. This allows it to spread rapidly even on the surfaces of diffusion plates made of difficult-to-wet polycarbonate and polymethyl methacrylate materials, effectively solving the problem of coating defects such as pinholes and fisheyes that are easily generated by traditional coating solutions. Furthermore, the good compatibility between the perfluoropolyether-modified wetting agent and the bactericidal coating solution system avoids migration problems that may be caused by ordinary wetting agents, synergistically ensuring the uniformity and stability of the coating.

[0025] In one specific feasible implementation, the defoamer is an organosilicone defoamer.

[0026] By adopting the above technical solution, the silicone molecules in the silicone defoamer are very stable and difficult to decompose by reactive oxygen species generated by photocatalysis, thus providing a long-lasting antifoaming effect. More importantly, the silicone molecules will not undergo harmful chemical reactions with rare earth modified titanium dioxide and will not poison the active sites of the catalyst, thereby ensuring the durability of the bactericidal efficacy. Furthermore, the silicone defoamer can withstand temperature changes during preparation and storage without performance degradation. While achieving highly efficient defoaming, the silicone defoamer will not cause severe pinholes due to poor compatibility with the resin, nor will it produce visible light scattering points due to excessively large particles, maximizing the high light transmittance and clarity of the coating.

[0027] Thirdly, this application provides a method for preparing a bactericidal coating liquid for an optical diffusion plate, employing the following technical solution: A method for preparing a bactericidal coating liquid for an optical diffusion plate includes the following preparation steps: S1-3. Add the dispersant and wetting agent to part of the deionized water, add rare earth modified titanium dioxide and stir to mix, to obtain a bactericidal slurry; S2-3. Add the film-forming resin to the remaining deionized water and stir to mix to obtain a resin solution; S3-3. Add the resin liquid obtained in step S2-3 to the bactericidal functional slurry obtained in step S1-3, add defoamer and stir to mix, adjust the pH value of the system to 7.5-8.5, discharge and let stand to mature, and obtain rare earth modified bactericidal coating liquid.

[0028] The rare earth modified bactericidal coating liquid prepared by the above steps has long-term stability and exhibits high efficiency photocatalytic bactericidal activity and resistance to photocatalytic degradation under indoor visible light conditions.

[0029] In summary, this application includes at least one of the following beneficial technical effects: 1. This application improves the bactericidal coating by adding rare earth modified titanium dioxide to the bactericidal coating solution, thereby enabling the bactericidal coating to have high efficiency photocatalytic bactericidal activity and resistance to photocatalytic degradation under indoor visible light conditions.

[0030] 2. This application utilizes cerium and lanthanum co-doped nano-titanium dioxide as a catalyst in the bactericidal coating liquid, enabling the bactericidal coating to synergistically possess both highly efficient bactericidal properties and excellent optical performance.

[0031] 3. This application uses polyether-b-poly(acrylate-co-silane) block copolymer as a dispersant for rare earth modified bactericidal coating liquid, which can significantly improve the adhesion and dispersion stability of the bactericidal coating. Detailed Implementation

[0032] The present application will be further described in detail below with reference to embodiments and comparative examples: Some of the raw materials used in the examples and comparative examples: Cerium nitrate hexahydrate (CAS: 10294-41-4, molar mass approximately 434.24 g / mol), lanthanum nitrate hexahydrate (CAS: 100587-94-8, molar mass approximately 433.03 g / mol), 2-(dodecyltrithiocarbonate)-2-methylpropionic acid (CAS: 461642-78-4), and 4-dimethylaminopyridine (CAS: 1122-58-3) were all purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Polyethylene glycol monomethyl ether (brand: BTJ008, model: MPEG2000, purchased from Jiangsu Bos Biotechnology Co., Ltd.); 3-(trimethoxysilyl)propyl-2-methyl-2-acrylate (silane coupling agent KH570, CAS: 2530-85-0, purchased from Guangzhou Leshi Biotechnology Co., Ltd.); waterborne acrylic resin (model: S-60L, purchased from Jingzhou Yinjie Chemical Co., Ltd.); perfluoropolyether modified wetting agent (model: F9120, purchased from Guangdong Aona Polymer Co., Ltd.). Limited Liability Company); Nano silica sol (brand name: GraceLudoxHS-40, purchased from Grace Trading (Shanghai) Co., Ltd.); Organosilicon defoamer (brand name: BYK-066N, purchased from Xiamen Kangdilong Trading Co., Ltd.); Nano titanium dioxide (item number: XFI83, type: anatase nano titanium dioxide, purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.); Nonylphenol polyoxyethylene ether (model: NP-40, purchased from Shanghai Hualan Chemical Technology Co., Ltd.); High-performance dispersant Dispuer S19 (brand name: Disuper S19, purchased from Shanghai Core New Materials Technology Co., Ltd.).

[0033] Unless otherwise specified, all raw materials used in the examples and comparative examples are commercially available products.

[0034] Preparation Example 1 The preparation steps of cerium and lanthanum co-doped nano-titanium dioxide photocatalyst are as follows: S1-1. Dissolve 6.81 g (20 mmol) of tetrabutyl titanate in 40 mL of anhydrous ethanol, denoted as solution A; dissolve 0.174 g (0.4 mmol) of cerium nitrate hexahydrate and 0.087 g (0.2 mmol) of lanthanum nitrate hexahydrate in 20 mL of deionized water, denoted as solution B. Add solution B dropwise to solution A at 800 rpm. Add ammonia dropwise until the pH of the mixture reaches 7.5. Stir for 2 hours. Transfer the reaction solution to a stainless steel high-pressure reactor lined with polytetrafluoroethylene. Heat the reactor to 150°C in an oven and react for 24 hours. Centrifuge and wash the mixture three times alternately with deionized water and anhydrous ethanol. Dry under vacuum at 80°C for 9 hours to obtain the cerium and lanthanum co-doped titanium dioxide precursor. S2-1. Place the cerium and lanthanum co-doped titanium dioxide precursor obtained in step S1-1 into a crucible, place it in a muffle furnace, and heat it to 450°C at a heating rate of 5°C / min under an air atmosphere, and hold it at that temperature for 3 hours to obtain cerium and lanthanum co-doped nano-titanium dioxide.

[0035] Preparation Example 2 The only difference between Preparation Example 2 and Preparation Example 1 is that in Preparation Example 2, 0.174 g (0.4 mmol) of cerium nitrate hexahydrate and 0.087 g (0.2 mmol) of lanthanum nitrate hexahydrate in step S1-1 are replaced with 0.261 g (0.6 mmol) of cerium nitrate hexahydrate to prepare cerium-doped nano-titanium dioxide.

[0036] Preparation Example 3 The only difference between Preparation Example 3 and Preparation Example 1 is that in Preparation Example 3, 0.174 g (0.4 mmol) of cerium nitrate hexahydrate and 0.087 g (0.2 mmol) of lanthanum nitrate hexahydrate in step S1-1 are replaced with 0.260 g (0.6 mmol) of lanthanum nitrate hexahydrate to prepare lanthanum-doped nano-titanium dioxide.

[0037] Preparation Example 4 The preparation steps of the polyether-b-poly(acrylate-co-silane) block copolymer are as follows: S1-2. Dissolve 10g of polyethylene glycol monomethyl ether, 1.65g of 2-(dodecyltrithiocarbonate)-2-methylpropionic acid, and 0.12g of 4-dimethylaminopyridine in 80mL of dichloromethane. Replace the nitrogen gas and cool the mixture to 0°C in an ice-water bath. Add 20mL of a dichloromethane solution of N,N'-dicyclohexylcarbodiimide (containing 1.24g of N,N'-dicyclohexylcarbodiimide dissolved in dichloromethane) dropwise using a constant pressure dropping funnel. After the addition is complete, remove the ice bath and allow the reaction system to slowly rise to room temperature. Continue stirring the reaction under nitrogen protection for 24 hours. Filter the solid impurities from the reaction solution and pour the filtrate into 200mL of diethyl ether. Filter the precipitated solid and wash it three times with diethyl ether. Dry the obtained solid under vacuum at 30°C for 24 hours to obtain the macromolecular RAFT reagent.

[0038] S2-2. Dissolve 2g of the macromolecular RAFT reagent obtained in step S1-2, 2.16g of acrylic acid, 1.48g of 3-(trimethoxysilyl)propyl-2-methyl-2-acrylate, and 16.4mg of azobisisobutyronitrile in 30mL of 1,4-dioxane, replace with nitrogen, heat to 70°C and stir for 8 hours. Pour 150mL of n-hexane into the reaction solution, filter out the precipitated solid, redissolve the solid in 20mL of tetrahydrofuran, and dialyze against deionized water in a dialysis bag (molecular weight cutoff MWCO = 3500Da) for 48 hours, changing the water every 8 hours. Freeze-dry the dialyzed solution to obtain a polyether-b-poly(acrylate-co-silane) block copolymer. Example

[0039] Example 1 The preparation method of the bactericidal coating solution is as follows: S1-3. 1.5g of the polyether-b-poly(acrylate-co-silane) block copolymer prepared in Preparation Example 4 and 0.65g of the perfluoropolyether modified wetting agent were added to 60g of deionized water, and 1.75g ​​of the cerium and lanthanum co-doped nano-titanium dioxide prepared in Preparation Example 1 were added. The mixture was stirred at 900rpm for 1 hour to obtain a bactericidal slurry.

[0040] S2-3. Add 1.45g of water-based acrylic resin to 33.25g of deionized water and stir at 500rpm for 30 minutes to obtain resin solution; S3-3. Add the resin liquid obtained in step S2-3 to the bactericidal functional slurry obtained in step S1-3, stir at 600 rpm for 40 minutes, add 1.0 g of nano silica sol and stir for 15 minutes, add 0.4 g of organosilicon defoamer, reduce the speed to 350 rpm and stir for 15 minutes, adjust the pH value of the system to 8 with ammonia water, and let it stand for 24 hours after discharge to obtain rare earth modified bactericidal coating liquid.

[0041] Example 2 The only difference between Example 2 and Example 1 is that in step S1-3 of Example 2, 1.75g ​​of the cerium and lanthanum co-doped nano-titanium dioxide prepared in Example 1 is replaced with 1.75g ​​of the cerium-doped nano-titanium dioxide prepared in Example 2.

[0042] Example 3 The only difference between Example 3 and Example 1 is that in step S1-3 of Example 3, 1.75g ​​of the cerium and lanthanum co-doped nano-titanium dioxide prepared in Example 1 is replaced with 1.75g ​​of the lanthanum-doped nano-titanium dioxide prepared in Example 3.

[0043] Example 4 The only difference between Example 4 and Example 1 is that in step S1-3 of Example 4, 1.5g of the polyether-b-poly(acrylate-co-silane) block copolymer prepared in Example 4 is replaced with 1.5g of nonylphenol polyoxyethylene ether.

[0044] Example 5 The only difference between Example 5 and Example 1 is that in steps S1-3 of Example 5, 1.5g of the polyether-b-poly(acrylate-co-silane) block copolymer prepared in Example 4 is replaced with 1.5g of the high-performance dispersant Dispuer S19.

[0045] Example 6 The only difference between Example 6 and Example 1 is that in steps S1-3 of Example 6, 1.5g of the polyether-b-poly(acrylate-co-silane) block copolymer prepared in Example 4 is replaced with 0.75g of nonylphenol polyoxyethylene ether and 0.75g of high-performance dispersant Dispuer S19.

[0046] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that in steps S1-3 of Comparative Example 1, 1.75g ​​of the cerium and lanthanum co-doped nano-titanium dioxide prepared in Example 1 was replaced with 1.75g ​​of nano-titanium dioxide.

[0047] The antibacterial coating solutions prepared in each embodiment and comparative example were applied at a concentration of 35 g / m³. 2 The coating amount was sprayed onto a diffusion plate sample made of polycarbonate. These samples were then placed in an oven and the oven temperature was set to 60°C to cure the coating, resulting in coated samples with antibacterial coatings from each embodiment and comparative example.

[0048] The coating samples prepared in each embodiment and comparative example were subjected to a 1000-hour accelerated aging test under a xenon lamp according to GB / T 1865-2009 standard. Before aging and at the 1000-hour mark, the coating samples were subjected to a cross-cut adhesion test according to GB / T 9286-2021 "Paints and Varnishes - Cross-cut Test", and their bactericidal performance was tested according to GB / T 21866-2008 "Antibacterial Coatings (Films) - Determination of Antibacterial Properties and Antibacterial Effect". The bacterium used in the bactericidal test was Staphylococcus aureus, strain number ATCC 8799. The test results are recorded in Table 1.

[0049] Table 1 shows the adhesion, gloss retention, and color difference test data of Examples 1-6 and Comparative Example 1 before and after the 1000h aging test. Sample No. Initial adhesion (grade) Adhesion after 1000h (grade) Initial sterilization rate (%) Sterilization rate after 1000h (%) Example 1 0 1 99.99 99.89 Example 2 0 2 97.76 90.32 Example 3 0 2-3 96.13 89.33 Example 4 1 4 85.95 58.47 Example 5 1 4 82.55 56.06 Example 6 1 4 89.84 59.46 Comparative Example 1 1 5 (large area peeling) 67.41 25.92 Fourier transform infrared spectroscopy (GB / T 6040-2019) was used to analyze the changes in the chemical structure of the coating sample after 1000 hours of aging test, and the test results are recorded in Table 2.

[0050] Table 2. Infrared spectral data of the coating chemical structure after 1000h aging tests in Examples 1-3 and Comparative Example 1. Sample No. Change in intensity of C-H peak (2920 cm⁻¹) Change in intensity of C=0 peak (-1730 cm⁻¹) Chemical structure stability Example 1 Intensity slightly decreased (<5%) Peak position stable, intensity almost unchanged Excellent Example 2 Intensity weakened (~15%) Peak position slightly shifted, intensity weakened (~10%) Good Example 3 Intensity weakened (~18%) Peak position slightly shifted, intensity weakened (~12%) Good Comparative Example 1 Intensity almost disappeared (>80%) Peak position disappeared, converted to a broad peak Severe degradation Based on Examples 1, 2-3, and Comparative Example 1, and referring to Tables 1 and 2, it can be seen that the coating sample of Example 1, after a 1000-hour aging test, exhibits better adhesion, bactericidal performance, and resistance to photocatalytic degradation than Examples 2-3 and Comparative Example 1. This may be because, in the bactericidal coating, cerium and lanthanum, two rare earth elements, are co-incorporated into the lattice of nano-titanium dioxide, resulting in a Ce³⁺ / Ce ratio. 4 La³⁺ acts as an “electron intermediate” to effectively separate charges, while La³⁺ acts as a “structural stabilizer” to give the photocatalyst a smaller and more stable highly active surface. The synergistic optimization of the two makes the photocatalytic reaction more efficient and mild, reducing the destructive impact on the coating’s structure. This results in more stable mechanical properties (adhesion) during long-term aging. Furthermore, the polyether-b-poly(acrylate-co-silane) block copolymer enhances the coating’s “skeleton structure” to resist internal and external stresses, synergistically constructing a stable chemical network at the interface and jointly improving the coating’s long service life.

[0051] Combining Examples 1 and 4-6, and referring to Table 1, it can be seen that the adhesion and bactericidal performance test results of the coating sample of Example 1 after 1000 hours of aging test are better than those of Examples 4-6. This may be because the silane groups at the ends of the polyether-b-poly(acrylate-co-silane) block copolymer can be hydrolyzed and condensed during the curing process. On the one hand, they form covalent bonds with the functional groups on the surface of the polycarbonate diffusion plate sample, and on the other hand, they form a three-dimensional network with the film-forming resin and themselves inside the coating. This chemical anchoring effect provides far superior performance compared to traditional dispersants (nonylphenol). The interfacial bonding force of polyoxyethylene ether (Dispuer S19) through physical adsorption ensures excellent adhesion even after long-term aging. Furthermore, the polyether-b-poly(acrylate-co-silane) block copolymer connects linear resin molecular chains into a stable three-dimensional network structure through covalent cross-linking points formed by its silane segments. This network effectively disperses external stresses (such as thermal stress and shrinkage stress), and even if some resin segments break due to aging, the entire network structure remains intact, ensuring that the bactericidal coating can continue to exert its bactericidal effect stably.

[0052] The rare-earth-modified bactericidal coating solution prepared in this application, through the core combination of cerium-lanthanum co-doped titanium dioxide and polyether-b-poly(acrylate-co-silane) block copolymer, not only exhibits optimal durability in terms of adhesion and photocatalytic bactericidal performance, but also demonstrates excellent resistance to photocatalytic degradation at the molecular level. This synergistic effect effectively solves the life cycle bottleneck of long-term service of photocatalytic coatings, and the technical effect is significantly better than single-component modification or the use of traditional additives.

[0053] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A rare-earth modified titanium dioxide photocatalyst, characterized in that, The rare earth modified titanium dioxide is anatase-type nano-titanium dioxide with rare earth elements doped in its crystal lattice. The rare earth elements are selected from one or more of lanthanum, cerium, samarium, europium, neodymium, and yttrium.

2. The rare earth-modified titanium dioxide photocatalyst according to claim 1, characterized in that, The rare earth modified titanium dioxide is cerium and lanthanum co-doped nano-titanium dioxide.

3. The rare earth-modified titanium dioxide photocatalyst according to claim 2, characterized in that, The preparation steps of the cerium and lanthanum co-doped nano-titanium dioxide are as follows: S1-1. Dissolve tetrabutyl titanate in anhydrous ethanol, denoted as solution A; dissolve cerium nitrate hexahydrate and lanthanum nitrate hexahydrate in deionized water, denoted as solution B; add solution B to solution A, adjust the pH of the mixture to 7.0-8.0, stir and mix, and then perform hydrothermal reaction. Post-treatment yields cerium and lanthanum co-doped titanium dioxide precursor. S2-1. The cerium and lanthanum co-doped titanium dioxide precursor obtained in step S1-1 is calcined at 400-500°C in air atmosphere to obtain cerium and lanthanum co-doped nano-titanium dioxide.

4. A bactericidal coating solution for an optical diffusion plate, characterized in that, Includes the following components by weight percentage: The rare earth modified titanium dioxide photocatalyst according to any one of claims 1-3 comprises 1.5-2.0%, film-forming resin 1.2-1.7%, dispersant 1.2-1.8%, wetting agent 0.5-0.8%, defoamer 0.3-0.5%, and deionized water 90-96%.

5. The optical diffusion plate bactericidal coating liquid according to claim 4, characterized in that, The dispersant is a polyether-b-poly(acrylate-co-silane) block copolymer, and its preparation steps are as follows: S1-2. Polyethylene glycol monomethyl ether, RAFT reagent and 4-dimethylaminopyridine are dissolved in dichloromethane, nitrogen gas is replaced, and the mixture is cooled to 0-5°C in an ice-water bath. A dichloromethane solution of N,N'-dicyclohexylcarbodiimide is added, and the mixture is heated to room temperature and stirred to react. The reaction is then post-treated to obtain the macromolecular RAFT reagent. S2-2, Dissolve the macromolecular RAFT reagent, acrylic acid, 3-(trimethoxysilyl)propyl-2-methyl-2-acrylate, and initiator obtained in step S1-2 in 1,4-dioxane, replace with nitrogen, heat to 65-75°C for polymerization, and then perform post-treatment to obtain polyether-b-poly(acrylate-co-silane) block copolymer.

6. The optical diffuser plate bactericidal coating liquid according to claim 4, characterized in that, It also includes nano-silica sol.

7. The optical diffusion plate bactericidal coating solution according to claim 4, characterized in that, The film-forming resin is an aqueous acrylic resin.

8. The optical diffusion plate bactericidal coating liquid according to claim 4, characterized in that, The wetting agent is a perfluoropolyether modified wetting agent.

9. The optical diffusion plate bactericidal coating liquid according to claim 4, characterized in that, The defoamer is an organosilicone defoamer.

10. A method for preparing an optical diffusion plate bactericidal coating liquid as described in any one of claims 4-9, characterized in that, The preparation steps include the following: S1-3. Add the dispersant and wetting agent to part of the deionized water, add rare earth modified titanium dioxide and stir to mix, to obtain a bactericidal slurry; S2-3. Add the film-forming resin to the remaining deionized water and stir to mix to obtain a resin solution; S3-3. Add the resin liquid obtained in step S2-3 to the bactericidal functional slurry obtained in step S1-3, add defoamer and stir to mix, adjust the pH value of the system to 7.5-8.5, discharge and let stand to mature, and obtain rare earth modified bactericidal coating liquid.