Silicon-titanium composite anti-fog coating, and preparation method and application thereof

Abstract

This invention discloses a silicon-titanium composite anti-fogging coating, its preparation method, and its application. The preparation method includes: mixing silica sol with a block copolymer and subjecting the mixture to aging treatment to obtain a composite silica sol; mixing the composite silica sol, titanium dioxide sol, a nonionic water-soluble polymer, a first metal ion dopant, and a second metal ion dopant and subjecting the mixture to aging treatment to obtain a precursor sol; and applying the precursor sol to a substrate surface and sequentially performing curing and annealing treatments to obtain the silicon-titanium composite anti-fogging coating. The silicon-titanium composite anti-fogging coating provided by this invention is suitable for transparent polymer flexible substrates such as PC substrates, can be annealed at low temperatures to form a film, and has good anti-fogging effect.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, specifically to silicon-titanium composite anti-fog coatings, their preparation methods, and applications. Background Technology

[0002] Protective transparent windows / face shields have important applications in medical equipment, disaster relief, aerospace, optical devices, and vehicle surfaces. For example, the face shield of heavy-duty chemical protective suits can provide effective protection in high-temperature, high-humidity, and highly corrosive environments, preventing harmful substances from directly contacting the skin and eyes and ensuring the safety of the user.

[0003] However, in practical applications, fogging often occurs on the surface of windows due to temperature or humidity changes, significantly reducing transparency, severely affecting visibility, and posing safety hazards. Anti-fog coatings on the market mainly reduce fog condensation through hydrophilic materials or micro / nanostructure designs, thereby improving the anti-fog performance of transparent windows. Currently, there are two main effective anti-fog strategies. The first is active anti-fog, which relies on conductive coatings and uses electrical heating to remove fog; however, this method is costly, poses significant safety risks, and has obvious limitations in application. The second method modifies the microstructure and chemical properties of the substrate surface to adjust the affinity between the solid interface and water droplets, thus achieving anti-fog functionality. This is mainly divided into hydrophobic and hydrophilic surfaces. Compared to hydrophobic surfaces, this type of anti-fog coating based on surface state regulation has a simpler preparation process, greater versatility, and more functional possibilities, meeting the needs of different application scenarios.

[0004] Patent CN103771721A discloses a method for preparing a superhydrophilic transparent anti-fog film. This method uses tetraethyl orthosilicate as a raw material to prepare nano-SiO2 sol and tetrabutyl titanate as a raw material to prepare nano-TiO2 sol. The silica sol and titanium sol are mixed in a specific ratio to prepare a SiO2 / TiO2 sol. Films of different layers are then prepared on a pre-treated glass substrate by spin coating, followed by annealing in a muffle furnace. This method uses simple equipment, is low-cost, and produces films with high light transmittance. However, to improve the film thickness and performance, multiple spin coating and drying processes are required, increasing time and steps. Furthermore, the anti-fog effect of the superhydrophilic film decays significantly over time, and durability remains a concern.

[0005] Patent CN114806238A discloses a superhydrophilic, wear-resistant, composite anti-reflective, and anti-fogging coating, its preparation method, and its application. The method involves mixing silica sol with a block copolymer and subjecting it to aging treatment to obtain a composite silica sol; mixing the composite silica sol, titanium dioxide sol, a nonionic water-soluble polymer, and a metal ion dopant and subjecting them to aging treatment to obtain a precursor sol; and applying the precursor sol to a substrate surface and annealing it to obtain the superhydrophilic, wear-resistant, composite anti-reflective, and anti-fogging coating. This superhydrophilic, wear-resistant, composite anti-reflective, and anti-fogging coating exhibits broad-spectrum anti-reflective properties and can achieve long-term anti-fogging. However, its adhesion decreases after reducing the heat treatment temperature, and its film formation effect on flexible substrates such as PC is poor, resulting in a loss of anti-fogging effect.

[0006] Existing anti-fogging coating technologies for flexible substrates face multiple technical bottlenecks. For example, the low glass transition temperature of substrates (PET, PC, etc.) means that traditional high-temperature processes (such as sintering at 400℃) can lead to substrate deformation or performance degradation, necessitating the development of low-temperature curing technologies. Furthermore, the coating is prone to peeling or cracking when the flexible substrate is repeatedly bent or deformed, affecting device lifespan, requiring improved coating adhesion. The coating must also meet multifunctional requirements such as weather resistance and optical transparency, while adapting to extreme environments like high humidity and low temperatures. Therefore, it is necessary to develop a simple, efficient, and cost-effective composite coating with high and low temperature anti-fogging properties on polymer substrates through innovative material synthesis combined with optimized coating preparation processes. Summary of the Invention

[0007] The main objective of this invention is to provide a silicon-titanium composite anti-fog coating, its preparation method, and its application, so as to overcome the shortcomings of the prior art.

[0008] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0009] One aspect of the present invention provides a method for preparing a silicon-titanium composite anti-fog coating, comprising:

[0010] A composite silica sol was prepared by mixing silica sol with a block copolymer and subjecting the mixture to aging treatment.

[0011] The composite silica sol, titanium dioxide sol, nonionic water-soluble polymer, first metal ion dopant and second metal ion dopant are mixed and aged to obtain a precursor sol; the first metal ion dopant includes an aluminum-based compound.

[0012] Furthermore, the precursor sol is applied to the substrate surface and then cured and annealed sequentially to obtain a silicon-titanium composite anti-fog coating.

[0013] Another aspect of the present invention provides a silicon-titanium composite anti-fog coating prepared by the aforementioned preparation method, wherein the surface of the silicon-titanium composite anti-fog coating has a contact angle with water of 0 to 21°C, an average transmittance of 89.17% to 94.78% in the 400 to 1100 nm wavelength band, and a thickness of 100 to 300 nm.

[0014] Another aspect of the present invention provides the use of the aforementioned silicon-titanium composite anti-fog coating in the field of anti-fog or in the preparation of transparent anti-fog materials.

[0015] Compared with the prior art, the present invention has at least the following advantages:

[0016] Compared with existing technologies, the present invention has the following beneficial effects:

[0017] 1) The silicon-titanium composite anti-fog coating provided by the present invention can achieve an average transmittance of 92.34% in the 400-1100nm band, which is 2.32% higher than that of blank PC, and has obvious broadband anti-reflection characteristics.

[0018] 2) The silicon-titanium composite anti-fog coating provided by the present invention is suitable for transparent polymer flexible substrates such as PC substrates. It can be successfully annealed on PC substrates at low temperature to form a film. The water contact angle of the film surface can reach 18°, and the film surface achieves high and low temperature anti-fog effect. Among them, the high temperature anti-fog exhibits good instant anti-fog characteristics.

[0019] 3) The preparation method provided by the present invention, through metal ion doping, staged aging, polymer synergy and gradient annealing design, achieves high adhesion, broad spectrum anti-reflection and long-lasting anti-fogging effect while significantly reducing curing temperature, solves the technical bottleneck of flexible substrate coating, and has significant industrial application value. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1a This is a water contact angle test diagram of the silicon-titanium composite anti-fog coating prepared on a PC substrate in Example 1;

[0022] Figure 1b This is a water contact angle test diagram of the silicon-titanium composite anti-fog coating prepared on a PC substrate in Example 2;

[0023] Figure 1cThis is a water contact angle test diagram of the silicon-titanium composite anti-fog coating prepared on a PC substrate in Example 3;

[0024] Figure 1d This is a water contact angle test diagram of the silicon-titanium composite anti-fog coating prepared on a PC substrate in Example 4;

[0025] Figure 2 This is an optical transmittance curve of the silicon-titanium composite anti-fog coating prepared on a PC substrate in Example 1;

[0026] Figure 3 This is an optical reflectance curve of the silicon-titanium composite anti-fog coating prepared on a PC substrate in Example 1;

[0027] Figure 4 High-temperature anti-fogging test photos of silicon-titanium composite anti-fogging coatings prepared on PC substrates for Comparative Example 1 (left) and Example 1 (right);

[0028] Figure 5 High-temperature anti-fogging test photos of silicon-titanium composite anti-fogging coatings prepared on PC substrates in Examples 5 (left) and 6 (right);

[0029] Figure 6 Low-temperature anti-fogging test photos of silicon-titanium composite anti-fogging coatings prepared on PC substrates for blank PC (left) and Example 1 (right);

[0030] Figure 7 High-temperature anti-fogging test photos of silicon-titanium composite anti-fogging coatings prepared on PC substrates for Comparative Example 2 (left) and Comparative Example 3 (right). Detailed Implementation

[0031] The invention will be more fully understood by reading the following detailed description. However, it should be understood that the detailed description disclosed below is merely exemplary of the invention, which can be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as the basis for the claims and as a representative basis for teaching those skilled in the art to employ the invention in different ways in any suitable detailed embodiment.

[0032] As one aspect of the technical solution of this invention, a method for preparing a silicon-titanium composite anti-fog coating includes:

[0033] A composite silica sol was prepared by mixing silica sol with a block copolymer and subjecting the mixture to aging treatment.

[0034] The composite silica sol, titanium dioxide sol, nonionic water-soluble polymer, first metal ion dopant and second metal ion dopant are mixed and aged to obtain a precursor sol; the first metal ion dopant includes an aluminum-based compound.

[0035] Furthermore, the precursor sol is applied to the substrate surface and then cured and annealed sequentially to obtain a silicon-titanium composite anti-fog coating.

[0036] In some embodiments, the preparation method specifically includes: dispersing water, block copolymer, and hydrochloric acid in ethanol to form a block copolymer dispersion, then mixing the block copolymer dispersion with silica sol and aging it at 20-40°C for 2-4 days to obtain the composite silica sol.

[0037] In some preferred embodiments, the molar ratio of ethanol, water, block copolymer and hydrochloric acid is 175-190:35-50:0.05-0.10:0.03-0.05.

[0038] In some preferred embodiments, the block copolymer includes, but is not limited to, any one or a combination of two or more of PEG-PPO-PEO, PEO-PPO-PEO, PEO-PBO-PPO, PEO-PPO-PBO, PAA-PMMA-PAA, PMMA-PPO-PVA, PEG-PVP-PEO, and PBO-PEO.

[0039] In some preferred embodiments, the aluminum-based compound includes, but is not limited to, any one or a combination of two or more of aluminum trichloride hexahydrate, aluminum nitrate nonahydrate, aluminum sulfate octahydrate, and aluminum acetate.

[0040] In some embodiments, the preparation method specifically includes: adjusting the pH value of the composite silica sol to 1-3, then adding the titanium dioxide sol and stirring to form a mixture; then adding a nonionic water-soluble polymer, a first metal ion dopant, and a second metal ion dopant to the obtained mixture, stirring and mixing, and aging at 10-40°C for 1-2 days to obtain the precursor sol.

[0041] In some preferred embodiments, the mass ratio of the composite silica sol, titanium dioxide sol, nonionic water-soluble polymer, first metal ion dopant, and second metal ion dopant is 18–25: 0.5–2: 0.1–0.3: 0.1–0.5: 0.02–0.06.

[0042] In some preferred embodiments, the nonionic water-soluble polymer includes any one or a combination of two or more of polyethylene glycol, polyacrylamide, polyoxyethylene, polyvinyl alcohol, 2-hydroxyethyl ether cellulose, and polyvinylpyrrolidone.

[0043] In some preferred embodiments, the second metal ion dopant includes any one or a combination of two or more of the following: ferric chloride hexahydrate, zinc chloride, calcium chloride, ferric nitrate nonahydrate, zinc nitrate hexahydrate, cerium nitrate hexahydrate, iron oxide, zinc oxide, ferric acetylacetone, and cerium acetylacetone.

[0044] In some embodiments, the preparation method specifically includes: applying the precursor sol to the substrate surface using any one of the following methods: dip coating, spray coating, spin coating, dip coating, or scraping coating; then curing the obtained substrate at 50–100°C for 1–3 hours; and then annealing it at 80–200°C for 3–12 hours to obtain the silicon-titanium composite anti-fog coating.

[0045] In some implementations, the substrate includes a PC substrate.

[0046] In some embodiments, the preparation method further includes: reacting a mixed reaction system containing a monomer with a siloxane group, an acid catalyst, water, and ethanol at 50–70°C for 2–4 h to obtain the silica sol.

[0047] In some embodiments, the preparation method further includes: stirring and mixing a titanium source, an acid catalyst, and ethanol, and aging the mixture at 20–40°C for 3–7 days to obtain the titanium dioxide sol.

[0048] In some preferred embodiments, the molar ratio of ethanol, acid catalyst, water and monomer containing siloxane groups in the mixed reaction system is 350-400:0.002-0.006:80-110:95-120.

[0049] In some preferred embodiments, the acid catalyst includes any one or a combination of two or more of nitric acid, hydrochloric acid, acetic acid, sulfuric acid, hypochlorous acid, and hydrofluoric acid.

[0050] In some preferred embodiments, the monomer containing a siloxane group includes any one or a combination of two or more of tetraethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, tetramethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane, and 3-(2,3-epoxypropoxy)propyltriethoxysilane.

[0051] In some preferred embodiments, the titanium source includes any one or a combination of two or more of titanium tetrachloride, tetrabutyl titanate, isopropyl titanate, titanium sulfate, and titanium oxysulfate-sulfuric acid hydrate.

[0052] In some more specific embodiments, the preparation method of the silicon-titanium composite anti-fog coating includes the following steps:

[0053] (1) Substrate cleaning: Place the PC cut to a certain size on a cleaning rack, add deionized water to completely immerse the PC, sonicate for 8-10 min, and rinse with deionized water for 5-10 min; then place the cleaning rack in anhydrous ethanol and sonicate for 8-10 min, rinse with deionized water for 5-10 min, and continue sonicating with deionized water for 8-10 min; then place the cleaning rack in isopropanol and sonicate for 8-10 min, rinse with deionized water for 5-10 min, and sonicate with deionized water for 8-10 min, and rinse with deionized water for another 5 min; place the PC and the cleaning rack in a constant temperature oven at 50℃ to dry; finally, use an atmospheric plasma cleaner to perform plasma cleaning treatment on the dried PC, and introduce hydroxyl groups on the PC after treatment to facilitate the preparation of the anti-fog coating;

[0054] (2) Preparation of composite silica sol:

[0055] Preparation of silica sol: After adding acid catalyst, deionized water and monomers containing siloxane groups to anhydrous ethanol, heat and stir in an oil bath or water bath at 50-70°C for 2-4 hours to obtain silica sol. The molar ratio of anhydrous ethanol, acid catalyst, deionized water and monomers containing siloxane groups is 350-400:0.002-0.006:80-110:95-120.

[0056] Preparation of block copolymer dispersion: Deionized water, block copolymer, and hydrochloric acid are added sequentially to anhydrous ethanol and stirred until homogeneous. The molar ratio of anhydrous ethanol, deionized water, block copolymer, and hydrochloric acid is 175-190:35-50:0.05-0.10:0.03-0.05.

[0057] The block copolymer dispersion was slowly added dropwise to the stirred silica sol, and the composite silica sol was obtained after aging for 2-4 days.

[0058] (3) Titanium sol preparation: Add acid catalyst and titanium source solution to anhydrous ethanol and stir thoroughly for 2-4 hours, then age for 3-7 days to obtain titanium dioxide sol;

[0059] (4) Preparation of precursor sol: Add concentrated hydrochloric acid or concentrated nitric acid to the composite silica sol prepared in step (2) to adjust the pH to 1-3. After stirring evenly, slowly add the titanium dioxide sol prepared in step (3). After stirring for 6-12 hours, add the nonionic water-soluble polymer and the metal ion dopant in sequence. After stirring for 2-4 hours, age for 1-2 days. The mass ratio of composite silica sol, titanium dioxide sol, nonionic water-soluble polymer, first metal ion dopant and second metal ion dopant is 18-25:0.5-2:0.1-0.3:0.1-0.5:0.02-0.06.

[0060] (5) Preparation of composite coating: The precursor sol obtained in step (4) is coated on the polymer substrate treated in step (1), and then low-temperature curing is performed. The curing temperature is 50-100℃ and the curing time is 1-3 hours. Then, high-temperature annealing is performed. The annealing temperature is 80-200℃ and the annealing time is 3-12 hours.

[0061] As another aspect of the technical solution of the present invention, the silicon-titanium composite anti-fog coating prepared by the aforementioned preparation method has a surface contact angle with water of 0 to 21°, and an average transmittance of 89.17% to 94.78% in the 400 to 1100 nm wavelength band.

[0062] In some preferred embodiments, the thickness of the silicon-titanium composite anti-fog coating is 100–300 nm.

[0063] As another aspect of the technical solution of the present invention, it relates to the use of the aforementioned silicon-titanium composite anti-fog coating in the field of anti-fog or in the preparation of transparent anti-fog materials.

[0064] In this invention, metal ion doping (Al) is used. 3+ Catalytic reactions can lower the curing temperature to 50-200℃ while enhancing coating adhesion. This is achieved through the synergistic effect of block copolymers and metal ions (e.g., PEO-PPO-PEO copolymers with Al). 3+ (Combination) to disperse micelles and enhance chemical bonding, thereby improving coating flexibility. Stepped temperature curing, combined with sol-gel crosslinking properties, reduces thermal stress.

[0065] In summary, this invention, based on SiO2-TiO2-based hydrophilic films, achieves a stable hydrophilic surface through sol-gel synthesis technology and metal ion doping. The added metal ions or their complexes can form stable chemical bonds with other components in the sol, and combined with a low-temperature gradient annealing process, achieve overall structural stability of the coating while simultaneously obtaining high-temperature and low-temperature anti-fogging properties on flexible transparent substrates.

[0066] The present invention is further illustrated below by way of examples, but the invention is not limited to the scope of the examples described. All reagents and raw materials used in the following examples are commercially available, and test methods not specifically specified are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0067] Example 1

[0068] (1) Substrate cleaning: PC cut to a certain size is placed on a cleaning rack, and deionized water is added to completely immerse the PC. After ultrasonication for 8 minutes, it is rinsed with deionized water for 5 minutes. Then, the cleaning rack is placed in anhydrous ethanol and ultrasonicated for 8 minutes, rinsed with deionized water for 5 minutes, and then ultrasonicated with deionized water for another 8 minutes. Then, the cleaning rack is placed in isopropanol and ultrasonicated for 8 minutes, rinsed with deionized water for 5 minutes, and ultrasonicated with deionized water for 8 minutes, and then rinsed with deionized water for another 5 minutes. The PC and the cleaning rack are placed in a constant temperature oven at 50°C to dry. Finally, the dried PC is subjected to plasma cleaning treatment using an atmospheric plasma cleaner. After treatment, hydroxyl groups are introduced on the PC to facilitate the preparation of the anti-fog coating.

[0069] (2) Preparation of composite silica sol:

[0070] Preparation of silica sol: Take 30 mL of anhydrous ethanol, add 40 μL of 0.1 M hydrochloric acid, 2 mL of water and 20 mL of tetraethyl orthosilicate in sequence, heat in an oil bath at 50 °C, reflux and stir for 2 hours to obtain silica sol with a cross-linked network structure.

[0071] Preparation of block copolymer dispersion: Add 7 mL of deionized water, 10 g of block copolymer (PEO-PPO-PEO), and 4 mL of 0.1 M hydrochloric acid to 106 mL of anhydrous ethanol and stir until homogeneous.

[0072] The block copolymer dispersion was slowly added dropwise to the stirred silica sol, and the composite silica sol was obtained after aging at 30°C for 3 days.

[0073] (3) Titanium sol preparation: Add 10 μL of concentrated hydrochloric acid and 25 g of tetrabutyl titanate to 130 mL of anhydrous ethanol and stir for 2 hours. After aging at 30 °C for 7 days, titanium dioxide sol is obtained.

[0074] (4) Preparation of precursor sol: Add 20 μL of concentrated hydrochloric acid to the composite silica sol prepared in step (2) to adjust the pH to 2.5. After stirring evenly, slowly add the titanium sol prepared in step (3). After stirring for 2 hours, add 0.5 g polyethylene glycol, 0.1 g ferric chloride hexahydrate and 1.5 g aluminum chloride hexahydrate. Continue stirring for 4 hours and then age at 30°C for 2 days.

[0075] (5) Preparation of composite coating:

[0076] The precursor sol obtained in step (4) is pulled up on both sides of the PC substrate treated in step (1) at a speed of 2000 rpm to form two layers of the prepared precursor sol. First, it is cured at a low temperature of 60°C for 3 hours, and then it is annealed at a high temperature of 120°C for 6 hours.

[0077] The water contact angle test diagram of the silicon-titanium composite anti-fog coating prepared on the PC substrate in this embodiment is shown below. Figure 1a As shown, the water contact angle is 18°; its optical transmittance curve is as follows. Figure 2 As shown, the average transmittance in the 400–1100 nm wavelength range is 92.34% (from 90.02% to 92.34%), exhibiting broadband anti-reflection properties; its optical reflectance curve is shown in the figure. Figure 3 As shown, the average reflectivity in the 400–1100 nm band decreased by 2.32% (from 7.54% to 5.22%), exhibiting significant broadband anti-reflection characteristics. Figure 2 , Figure 3 This invention verifies that by designing a silicon-titanium composite nanostructure, a gradient refractive index layer is formed, reducing interface reflection loss and achieving anti-reflection and anti-reflection effects.

[0078] Example 2

[0079] (1) Substrate cleaning: PC cut to a certain size is placed on a cleaning rack, and deionized water is added to completely immerse the PC. After ultrasonication for 8 minutes, it is rinsed with deionized water for 5 minutes. Then, the cleaning rack is placed in anhydrous ethanol and ultrasonicated for 8 minutes, rinsed with deionized water for 5 minutes, and then ultrasonicated with deionized water for another 8 minutes. Then, the cleaning rack is placed in isopropanol and ultrasonicated for 8 minutes, rinsed with deionized water for 5 minutes, and ultrasonicated with deionized water for 8 minutes, and then rinsed with deionized water for another 5 minutes. The PC and the cleaning rack are placed in a constant temperature oven at 50°C to dry. Finally, the dried PC is subjected to plasma cleaning treatment using an atmospheric plasma cleaner. After treatment, hydroxyl groups are introduced on the PC to facilitate the preparation of the anti-fog coating.

[0080] (2) Preparation of composite silica sol:

[0081] Preparation of silica sol: Take 20 mL of anhydrous ethanol, add 30 μL of 0.1 M nitric acid, 3 mL of water, and 30 mL of tetramethoxysilane in sequence, heat in an oil bath at 60 °C, reflux, and stir for 3 hours to obtain a silica sol with a cross-linked network structure.

[0082] Preparation of block copolymer dispersion: Add 8 mL of deionized water, 9 g of block copolymer (PEG-PPO-PEO), and 3 mL of 0.1 M nitric acid to 110 mL of anhydrous ethanol and stir until homogeneous.

[0083] The block copolymer dispersion was slowly added dropwise to the stirred silica sol, and the composite silica sol was obtained after aging at 40°C for 3 days.

[0084] (3) Titanium sol preparation: Add 11 μL of concentrated nitric acid and 24 g of titanium sulfate to 110 mL of anhydrous ethanol and stir for 2 hours. After aging at 40 °C for 6 days, titanium dioxide sol is obtained.

[0085] (4) Preparation of precursor sol: Add 22 μL of concentrated hydrochloric acid to the composite silica sol prepared in step (2) to adjust the pH to 2.5. After stirring evenly, slowly add the titanium sol prepared in step (3). After stirring for 2 hours, add 0.4 g of polyvinyl alcohol, 0.15 g of ferric chloride hexahydrate and 1.0 g of aluminum chloride hexahydrate. Continue stirring for 4 hours and then age at 40°C for 1 day.

[0086] (5) Preparation of composite coating:

[0087] The precursor sol obtained in step (4) is pulled up on both sides of the PC substrate treated in step (1) at a speed of 2000 rpm to form two layers of the prepared precursor sol. First, it is cured at a low temperature of 50°C for 2 hours, and then it is annealed at a high temperature of 100°C for 8 hours.

[0088] The water contact angle test diagram of the silicon-titanium composite anti-fog coating prepared on the PC substrate in this embodiment is shown below. Figure 1b As shown, the water contact angle is 20°.

[0089] Example 3

[0090] (1) Substrate cleaning: PC cut to a certain size is placed on a cleaning rack, and deionized water is added to completely immerse the PC. After ultrasonication for 8 minutes, it is rinsed with deionized water for 5 minutes. Then, the cleaning rack is placed in anhydrous ethanol and ultrasonicated for 8 minutes, rinsed with deionized water for 5 minutes, and then ultrasonicated with deionized water for another 8 minutes. Then, the cleaning rack is placed in isopropanol and ultrasonicated for 8 minutes, rinsed with deionized water for 5 minutes, and ultrasonicated with deionized water for 8 minutes, and then rinsed with deionized water for another 5 minutes. The PC and the cleaning rack are placed in a constant temperature oven at 50°C to dry. Finally, the dried PC is subjected to plasma cleaning treatment using an atmospheric plasma cleaner. After treatment, hydroxyl groups are introduced on the PC to facilitate the preparation of the anti-fog coating.

[0091] (2) Preparation of composite silica sol:

[0092] Preparation of silica sol: Take 30 mL of anhydrous ethanol, add 40 μL of 0.1 M hydrochloric acid, 2 mL of water, and 20 mL of tetraethyl orthosilicate in sequence, heat in an oil bath at 60 °C, reflux, and stir for 3 hours to obtain a silica sol with a cross-linked network structure.

[0093] Preparation of block copolymer dispersion: Add 8 mL of deionized water, 7 g of block copolymer (PEG-PPO-PEO), and 5 mL of 0.1 M nitric acid to 100 mL of anhydrous ethanol and stir until homogeneous.

[0094] The block copolymer dispersion was slowly added dropwise to the stirred silica sol, and the composite silica sol was obtained after aging at 20°C for 4 days.

[0095] (3) Titanium sol preparation: Add 8 μL of concentrated nitric acid and 20 g of tetrabutyl titanate to 125 mL of anhydrous ethanol and stir for 2 hours. After aging at 20 °C for 7 days, titanium dioxide sol is obtained.

[0096] (4) Preparation of precursor sol: Add 19 μL of concentrated hydrochloric acid to the composite silica sol prepared in step (2) to adjust the pH to 2.5. After stirring evenly, slowly add the titanium sol prepared in step (3). After stirring for 2 hours, add 0.7 g polyethylene glycol, 0.1 g ferric chloride hexahydrate and 0.5 g aluminum chloride hexahydrate. Continue stirring for 4 hours and then age at 40°C for 2 days.

[0097] (5) Preparation of composite coating:

[0098] The precursor sol obtained in step (4) is pulled up on both sides of the PC substrate treated in step (1) at a speed of 2000 rpm to form two layers of the prepared precursor sol. First, it is cured at a low temperature of 80°C for 1 hour, and then it is annealed at a high temperature of 130°C for 3 hours.

[0099] The water contact angle test diagram of the silicon-titanium composite anti-fog coating prepared on the PC substrate in this embodiment is shown below. Figure 1c As shown, the water contact angle is 21°.

[0100] Example 4

[0101] (1) Substrate cleaning: PC cut to a certain size is placed on a cleaning rack, and deionized water is added to completely immerse the PC. After ultrasonication for 8 minutes, it is rinsed with deionized water for 5 minutes. Then, the cleaning rack is placed in anhydrous ethanol and ultrasonicated for 8 minutes, rinsed with deionized water for 5 minutes, and then ultrasonicated with deionized water for another 8 minutes. Then, the cleaning rack is placed in isopropanol and ultrasonicated for 8 minutes, rinsed with deionized water for 5 minutes, and ultrasonicated with deionized water for 8 minutes, and then rinsed with deionized water for another 5 minutes. The PC and the cleaning rack are placed in a constant temperature oven at 50°C to dry. Finally, the dried PC is subjected to plasma cleaning treatment using an atmospheric plasma cleaner. After treatment, hydroxyl groups are introduced on the PC to facilitate the preparation of the anti-fog coating.

[0102] (2) Preparation of composite silica sol:

[0103] Preparation of silica sol: Take 28 mL of anhydrous ethanol, add 42 μL of 0.1 M nitric acid, 2 mL of water and 22 mL of tetramethoxysilane in sequence, heat in an oil bath at 70 °C, reflux and stir for 2 hours to obtain silica sol with a cross-linked network structure.

[0104] Preparation of block copolymer dispersion: 11 mL of deionized water, 12 g of block copolymer (PEO-PBO-PPO), and 2 mL of 0.1 M nitric acid were added sequentially to 90 mL of anhydrous ethanol and stirred until homogeneous. The block copolymer dispersion was then slowly added dropwise to the stirred silica sol. After aging at 40 °C for 2 days, the composite silica sol was obtained.

[0105] (3) Titanium sol preparation: Add 8 μL of concentrated hydrochloric acid and 23 g of tetrabutyl titanate to 125 mL of anhydrous ethanol and stir for 2 hours. After aging at 40 °C for 5 days, titanium dioxide sol is obtained.

[0106] (4) Preparation of precursor sol: Add 18 μL of concentrated hydrochloric acid to the composite silica sol prepared in step (2) to adjust the pH to 2.5. After stirring evenly, slowly add the titanium sol prepared in step (3). After stirring for 2 hours, add 1 g of polyvinyl alcohol, 0.15 g of ferric chloride hexahydrate and 1.5 g of aluminum chloride hexahydrate. Continue stirring for 4 hours and then age at 20°C for 2 days.

[0107] (5) Preparation of composite coating:

[0108] The precursor sol obtained in step (4) is pulled up on both sides of the PC substrate treated in step (1) at a speed of 2000 rpm to form two layers of the prepared precursor sol. First, it is cured at a low temperature of 100°C for 1 hour, and then it is annealed at a high temperature of 80°C for 12 hours.

[0109] (6) High Accelerated Aging (HAST) Test

[0110] The coating obtained in step (5) was placed in a high-accelerated aging test chamber, with conditions set at 121°C and 97% relative humidity, and run continuously for 12 hours. The sample was removed after the test. Its water contact angle test diagram is shown below. Figure 1d As shown, the sample in this embodiment still maintains a water contact angle of 15° after 12 hours of high accelerated aging resistance test at 121°C and 97%RH (compared to 1000 hours of double 85 test).

[0111] Example 5

[0112] (1) Substrate cleaning: PC cut to a certain size is placed on a cleaning rack, and deionized water is added to completely immerse the PC. After ultrasonication for 8 minutes, it is rinsed with deionized water for 5 minutes. Then, the cleaning rack is placed in anhydrous ethanol and ultrasonicated for 8 minutes, rinsed with deionized water for 5 minutes, and then ultrasonicated with deionized water for another 8 minutes. Then, the cleaning rack is placed in isopropanol and ultrasonicated for 8 minutes, rinsed with deionized water for 5 minutes, and ultrasonicated with deionized water for 8 minutes, and then rinsed with deionized water for another 5 minutes. The PC and the cleaning rack are placed in a constant temperature oven at 50°C to dry. Finally, the dried PC is subjected to plasma cleaning treatment using an atmospheric plasma cleaner. After treatment, hydroxyl groups are introduced on the PC to facilitate the preparation of the anti-fog coating.

[0113] (2) Preparation of composite silica sol:

[0114] Preparation of silica sol: Take 24 mL of anhydrous ethanol, add 37 μL of 0.1 M acetic acid, 3 mL of water and 23 mL of tetraethyl orthosilicate in sequence, heat in an oil bath at 55 °C, reflux and stir for 4 hours to obtain silica sol with a cross-linked network structure.

[0115] Preparation of block copolymer dispersion: 12 mL of deionized water, 9 g of block copolymer (PEO-PPO-PBO), and 3 mL of 0.1 M hydrochloric acid were added sequentially to 115 mL of anhydrous ethanol and stirred until homogeneous. The block copolymer dispersion was then slowly added dropwise to the stirred silica sol. After aging at 30 °C for 3 days, the composite silica sol was obtained.

[0116] (3) Titanium sol preparation: Add 10 μL of concentrated hydrochloric acid and 21 g of titanium tetrachloride to 95 mL of anhydrous ethanol and stir for 2 hours. After aging at 40 °C for 6 days, titanium dioxide sol is obtained.

[0117] (4) Preparation of precursor sol: Add 20 μL of concentrated hydrochloric acid to the composite silica sol prepared in step (2) to adjust the pH to 2.5. After stirring evenly, slowly add the titanium sol prepared in step (3). After stirring for 2 hours, add 0.6 g polyethylene glycol, 0.1 g ferric chloride hexahydrate, 0.1 g cerium acetylacetone and 1.5 g aluminum chloride hexahydrate. Continue stirring for 4 hours and then age at 40°C for 2 days.

[0118] (5) Preparation of composite coating:

[0119] The precursor sol obtained in step (4) is pulled up on both sides of the PC substrate treated in step (1) at a speed of 2000 rpm to form two layers of the prepared precursor sol. First, it is cured at a low temperature of 70°C for 2 hours, and then it is annealed at a high temperature of 90°C for 7 hours.

[0120] Example 6

[0121] (1) Substrate cleaning: PC cut to a certain size is placed on a cleaning rack, and deionized water is added to completely immerse the PC. After ultrasonication for 8 minutes, it is rinsed with deionized water for 5 minutes. Then, the cleaning rack is placed in anhydrous ethanol and ultrasonicated for 8 minutes, rinsed with deionized water for 5 minutes, and then ultrasonicated with deionized water for another 8 minutes. Then, the cleaning rack is placed in isopropanol and ultrasonicated for 8 minutes, rinsed with deionized water for 5 minutes, and ultrasonicated with deionized water for 8 minutes, and then rinsed with deionized water for another 5 minutes. The PC and the cleaning rack are placed in a constant temperature oven at 50°C to dry. Finally, the dried PC is subjected to plasma cleaning treatment using an atmospheric plasma cleaner. After treatment, hydroxyl groups are introduced on the PC to facilitate the preparation of the anti-fog coating.

[0122] (2) Preparation of composite silica sol:

[0123] Preparation of silica sol: Take 30 mL of anhydrous ethanol, add 40 μL of 0.1 M hydrochloric acid, 2 mL of water, and 20 mL of tetramethoxysilane in sequence, heat in an oil bath at 50 °C, reflux, and stir for 2 hours to obtain a silica sol with a cross-linked network structure.

[0124] Preparation of block copolymer dispersion: 10 mL of deionized water, 8 g of block copolymer (PEG-PPO-PEO), and 5 mL of 0.1 M nitric acid were added sequentially to 105 mL of anhydrous ethanol and stirred until homogeneous. The block copolymer dispersion was then slowly added dropwise to the stirred silica sol. After aging at 30 °C for 3 days, the composite silica sol was obtained.

[0125] (3) Titanium sol preparation: Add 12 μL of concentrated hydrochloric acid and 24 g of titanium sulfate to 128 mL of anhydrous ethanol and stir for 2 hours. After aging at 30 °C for 7 days, titanium dioxide sol is obtained.

[0126] (4) Preparation of precursor sol: Add 18 μL of concentrated hydrochloric acid to the composite silica sol prepared in step (2) to adjust the pH to 2.5. After stirring evenly, slowly add the titanium sol prepared in step (3). After stirring for 2 hours, add 0.8 g of polyvinyl alcohol, 0.05 g of ferric chloride hexahydrate, 0.15 g of zinc chloride and 1.5 g of aluminum chloride hexahydrate. Continue stirring for 4 hours and then age at 10°C for 1 day.

[0127] (5) Preparation of composite coating:

[0128] The precursor sol obtained in step (4) is pulled up on both sides of the PC substrate treated in step (1) at a speed of 2000 rpm to form two layers of the prepared precursor sol. First, it is cured at a low temperature of 100°C for 3 hours, and then it is annealed at a high temperature of 110°C for 10 hours.

[0129] Comparative Example 1

[0130] Compared with Example 1, the difference is that in step (4), after stirring for 2 hours, 0.5g of polyethylene glycol and 0.1g of ferric chloride hexahydrate are added, and after stirring for 4 hours, the mixture is aged at 30°C for 2 days.

[0131] Comparative Example 2

[0132] Compared with Example 1, the difference is that in step (5), curing is not performed, and high-temperature annealing is performed directly.

[0133] Comparative Example 3

[0134] Compared with Example 1, the difference is that after curing in step (5), no high-temperature annealing is performed.

[0135] The anti-fog performance of Examples 1, 5, and 6 and Comparative Examples 1, 2, and 3 was tested, and the test results are shown in [reference needed]. Figures 4 to 7 .in Figure 6 These are comparison photos from a low-temperature anti-fogging test. The low-temperature anti-fogging test procedure is as follows: The sample was placed in a -25℃ freezer for 4 hours, then removed and the frost formation on the sample surface was observed. Figure 6 This verifies that the sample from Example 1 also exhibits good low-temperature anti-fogging performance. Figure 7 As can be seen, in the high-temperature anti-fog test, the coating of Comparative Example 2 showed some water droplets on the surface and the reference text below was distorted, indicating that the anti-fog effect was not ideal. In the high-temperature anti-fog test, the coating of Comparative Example 3 showed many small water droplets on the surface and the reference text below was not visible, indicating that the anti-fog effect was completely lost.

[0136] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0137] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a silicon-titanium composite anti-fog coating, characterized in that, include: A composite silica sol is prepared by mixing silica sol with a block copolymer and subjecting the mixture to aging treatment. The block copolymer is selected from any one or a combination of two or more of PEG-PPO-PEO, PEO-PPO-PEO, PEO-PBO-PPO, PEO-PPO-PBO, PAA-PMMA-PAA, PMMA-PPO-PVA, PEG-PVP-PEO, and PBO-PEO. A precursor sol is prepared by mixing the composite silica sol, titanium dioxide sol, nonionic water-soluble polymer, first metal ion dopant, and second metal ion dopant and subjecting the mixture to aging treatment. The first metal ion dopant is an aluminum-based compound selected from any one or a combination of two or more of aluminum trichloride hexahydrate, aluminum nitrate nonahydrate, aluminum sulfate octahydrate, and aluminum acetate. The second metal ion dopant is selected from any one or a combination of two or more of ferric chloride hexahydrate, zinc chloride, calcium chloride, ferric nitrate nonahydrate, zinc nitrate hexahydrate, cerium nitrate hexahydrate, iron oxide, zinc oxide, ferric acetylacetone, and cerium acetylacetone. The mass ratio of the composite silica sol, titanium dioxide sol, nonionic water-soluble polymer, first metal ion dopant, and second metal ion dopant is 18–25:0.5–2:0.1–0.3:0.1–0.5:0.02–0.

06. Furthermore, the precursor sol is applied to the substrate surface using any one of the following methods: dip coating, spray coating, spin coating, dip coating, or scraping coating. The obtained substrate is then cured at 50–100°C for 1–3 hours and annealed at 80–200°C for 3–12 hours to obtain a silicon-titanium composite anti-fog coating.

2. The preparation method according to claim 1, characterized in that... Specifically, the process involves dispersing water, block copolymer, and hydrochloric acid in ethanol to form a block copolymer dispersion, then mixing the block copolymer dispersion with silica sol and aging it at 20–40°C for 2–4 days to obtain the composite silica sol.

3. The preparation method according to claim 2, characterized in that, The molar ratio of ethanol, water, block copolymer and hydrochloric acid is 175-190:35-50:0.05-0.10:0.03-0.

05.

4. The preparation method according to claim 1, characterized in that... Specifically, it includes: The pH value of the composite silica sol is adjusted to 1-3, and then the titanium dioxide sol is added and stirred to form a mixture. Then, a nonionic water-soluble polymer, a first metal ion dopant, and a second metal ion dopant are added to the obtained mixture, stirred and mixed, and aged at 10-40°C for 1-2 days to obtain the precursor sol.

5. The preparation method according to claim 4, characterized in that, The nonionic water-soluble polymer includes any one or a combination of two or more of polyethylene glycol, polyacrylamide, polyoxyethylene, polyvinyl alcohol, 2-hydroxyethyl ether cellulose, and polyvinylpyrrolidone.

6. The preparation method according to claim 1, characterized in that, The substrate includes a PC substrate.

7. The preparation method according to claim 1, characterized in that... Also includes: The silica sol is prepared by reacting a mixed reaction system containing a monomer with a siloxane group, an acid catalyst, water, and ethanol at 50–70°C for 2–4 hours. And / or, the preparation method further includes: stirring and mixing a titanium source, an acid catalyst, and ethanol, and aging the mixture at 20–40°C for 3–7 days to obtain the titanium dioxide sol.

8. The preparation method according to claim 7, characterized in that, The molar ratio of ethanol, acid catalyst, water and monomer containing siloxane groups in the mixed reaction system is 350-400:0.002-0.006:80-110:95-120. And / or, the acid catalyst comprises any one or a combination of two or more of nitric acid, hydrochloric acid, acetic acid, sulfuric acid, hypochlorous acid, and hydrofluoric acid; And / or, the monomer containing a siloxane group includes any one or a combination of two or more of tetraethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, tetramethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane, and 3-(2,3-epoxypropoxy)propyltriethoxysilane; And / or, the titanium source includes any one or a combination of two or more of titanium tetrachloride, tetrabutyl titanate, isopropyl titanate, titanium sulfate, and titanium oxysulfate-sulfuric acid hydrate.

9. A silicon-titanium composite anti-fog coating prepared by the preparation method according to any one of claims 1-8, characterized in that, The contact angle between the surface of the silicon-titanium composite anti-fog coating and water is 0–21°C, the average transmittance in the 400–1100 nm wavelength band is 89.17%–94.78%, and the thickness of the silicon-titanium composite anti-fog coating is 100–300 nm.

10. The use of the silicon-titanium composite anti-fog coating as described in claim 9 in the field of anti-fog or in the preparation of transparent anti-fog materials.

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