Water-based poly-ceramic protective coating material and preparation method thereof

Abstract

The invention discloses a water-based poly-ceramic protective coating material and a preparation method thereof, and belongs to the technical field of coating materials, the water-based poly-ceramic protective coating material can be coated on the surface of kitchen utensils and then cured at a low temperature to form a compact ceramic film layer, has super-hydrophobicity and photocatalytic self-cleaning capability, and can be used for preparing a water-based poly-ceramic protective coating material by taking polyacrylic acid as an organic flexible chain segment. According to the invention, the titanium dioxide sol is co-crosslinked with the water-based titanium dioxide sol and the modified nitrogen-doped silica sol to form a three-dimensional cross-linked interpenetrating network, and the water-based titanium dioxide sol contains titanium dioxide, so that the coating can be endowed with photocatalytic self-cleaning performance and antibacterial property; in the modified nitrogen-doped silica sol, urea is used as a nitrogen source to be mixed with graphite micro-powder, urea molecules can penetrate into pores and interlayers of the graphite micro-powder, and the problem that in traditional doping, the nitrogen element only stays on the surface is solved; by means of uniform doping of the nitrogen element and grafting of perdecafluorooctyltriethoxysilane, the problems that original graphite is high in hydrophobicity and difficult to disperse in a water-based system can be solved.

Description

Technical Field

[0001] This invention belongs to the field of coating materials technology, specifically a water-based polyceramic protective coating material and its preparation method. Background Technology

[0002] In recent years, superhydrophilic functional surfaces, with their unique surface wettability, have shown promising application prospects in various fields such as building sanitary ware, biomedicine, antifouling materials, and electromechanical products, thus attracting widespread attention and achieving rapid development. However, in the field of kitchen utensils, the surface protection requirements are more unique—gas stoves, ovens, cookware, range hoods, and other equipment are exposed to high-temperature environments for extended periods. High-temperature heat effects easily cause oil and grease to adhere tightly to the surface and inner walls, making them difficult to clean. Currently, the industry mainly uses spray coatings to protect the surface of these kitchen utensils. However, existing coating technologies all have significant shortcomings and cannot fully meet the comprehensive requirements of "high temperature resistance, oil stain resistance, easy cleaning, and corrosion resistance."

[0003] Specifically, existing kitchen utensil coating technologies suffer from three main shortcomings: The first is the use of silicate coatings. While these form a basic protective layer, their structure is not dense, making them prone to foaming at high temperatures. This results in numerous pores within the coating, trapping oil and grime that are difficult to clean thoroughly. More importantly, when cleaning with detergents, the substrate metal corrodes due to the exposed pores, eventually causing the coating to peel off, posing a serious problem with corrosion resistance and durability. The second approach involves using phosphate, epoxy-modified silicone resin powder, and high-temperature curing agent powder to prepare coatings. While these coatings meet the requirements for high-temperature corrosion resistance and solve the stability problem at high temperatures, they completely lack the core functions of easy cleaning and oil resistance, failing to address the persistent problem of oil adhesion on kitchen utensils. The third option uses a fluoropolymer with a dual-terminal silane structure, which falls under the category of organic coatings. Although it has certain wear resistance and easy-to-clean properties, its temperature resistance is insufficient. It is only suitable for use in normal or medium-low temperature environments and cannot be adapted to the high-temperature working scenarios of kitchen appliances such as gas stoves and ovens. Under high temperatures, the coating is prone to softening and functional failure.

[0004] Chinese Patent No. CN118791894B discloses a nano-ceramic coating, a nano-ceramic coating method thereof, and its application. This method uses silica sol and polysiloxane as film-forming agents. Through the condensation and cross-linking of silica sol and polysiloxane, excessive tensile stress caused by shrinkage between sol particles and the substrate surface can be reduced, preventing the coating from self-cracking. Simultaneously, nanopowder is used as a filler to fill the molecular gaps after the silica sol dehydrates and condenses, and to reinforce the relatively formed network structure of the coating, thereby improving the coating's density and ensuring the formation of a crack-free coating. This prevents oil and grease residue from remaining in the coating, ensuring good cleanability and long-lasting durability. However, under long-term strong ultraviolet radiation, this coating may become a photocatalytic active center, accelerating the breakage of polysiloxane molecular chains, leading to a gradual roughening of the coating surface, decreased hydrophobicity, and ultimately loss of cleanability and durability. Summary of the Invention

[0005] The purpose of this invention is to provide an aqueous polyceramic protective coating material and its preparation method. The coating surface has superhydrophobicity and photocatalytic self-cleaning ability, and can decompose organic pollutants under ultraviolet irradiation, thereby keeping the surface clean.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing a water-based polyceramic protective coating material includes the following steps: S1. Titanium sulfate and ammonia water react through an acid-base neutralization reaction to generate metatitanic acid precipitate. Then, through hydrogen peroxide oxidation and ultraviolet irradiation, the metatitanic acid precipitate is dispersed to form an aqueous titanium dioxide sol.

[0007] S2. Urea and graphitized anthracite powder are doped together, and liquid carbon dioxide is introduced into a high-pressure reactor and then heated to obtain a nitrogen-doped graphite powder solution.

[0008] S3. Tetraethyl orthosilicate forms silica sol under the catalysis of dilute hydrochloric acid. The silica sol is mixed with nitrogen-doped graphite powder solution and then subjected to aging treatment to obtain nitrogen-doped silica sol.

[0009] S4. Modified nitrogen-doped silica sol is obtained by hydrolyzing and condensing the hydroxyl groups of nitrogen-doped silica sol with tridecafluorooctyltriethoxysilane in ethanol solution.

[0010] S5. A water-based polyceramic protective coating material is obtained by free radical polymerization of aqueous titanium dioxide sol, modified nitrogen-doped silica sol and acrylic acid solution.

[0011] Furthermore, the specific preparation steps of the aqueous titanium dioxide sol are as follows: A 0.1-0.2 mol / L aqueous solution of titanium oxysulfate and a 50-60% ammonia solution were added to a reaction vessel at a volume ratio of 50-60:270-280. The mixture was stirred for 20-40 minutes at 20-25°C and 500-600 rpm. After filtration, the filter cake was washed 2-4 times with deionized water and anhydrous ethanol until neutral. The cake was then vacuum dried at 60-70°C for 1-2 hours to obtain metatitanic acid precipitate. The metatitanic acid precipitate and a 20-30% hydrogen peroxide solution were added to the reaction vessel. The mixture was stirred for 20-40 minutes at 20-25°C and 500-600 rpm. Then, deionized water and a 1-2% isopropanol solution were added. The mixture was irradiated under a 254 nm UV lamp and stirred for 4-5 hours to obtain an aqueous titanium dioxide sol.

[0012] Furthermore, the ratio of metatitanic acid precipitate, hydrogen peroxide, deionized water, and isopropanol is 20-30g: 80-90mL: 50-60mL: 15-20mL.

[0013] Furthermore, the specific preparation steps of the nitrogen-doped graphite micropowder solution are as follows: Graphitized anthracite powder with an average particle size of 6-8 μm, polyethylene glycol as a dispersant, and a urea solution with a mass fraction of 3-4% were added to a high-pressure reactor. The mixture was stirred for 20-40 min at 30-35℃ and 500-600 r / min. Then, liquid carbon dioxide was pumped into the reactor to bring the carbon dioxide pressure inside the reactor to 35-40 MPa. This pressure was maintained for 1-2 h, and the carbon dioxide was discharged. This process was repeated 4-5 times. The mixture was then heated to 200-250℃ and stirred for another 2-3 h. After naturally cooling to room temperature, a nitrogen-doped graphite powder solution was obtained.

[0014] Furthermore, the ratio of graphitized anthracite powder, polyethylene glycol, urea solution, and liquid carbon dioxide is 50-60g: 1-2g: 20-25mL: 12-14mL.

[0015] Furthermore, the specific preparation steps of nitrogen-doped silica sol are as follows: A 1.8-2.0 g / L tetraethyl orthosilicate solution, deionized water, and 0.2-0.4 mol / L dilute hydrochloric acid were added to a reaction vessel and stirred for 20-40 minutes at 20-25 °C and 500-600 r / min. Then, a nitrogen-doped graphite powder solution was added, and the mixture was stirred and aged for 1-2 hours to obtain a nitrogen-doped silica sol.

[0016] Furthermore, the ratio of tetraethyl orthosilicate solution, deionized water, dilute hydrochloric acid, and nitrogen-doped graphite powder solution is 80-90 mL: 120-140 mL: 5-8 mL: 70-80 mL.

[0017] Furthermore, the specific preparation steps of the modified nitrogen-doped silica sol are as follows: Nitrogen-doped silica sol, tridecafluorooctyltriethoxysilane, anhydrous ethanol, and deionized water were added to a reaction vessel. The pH was adjusted to 3-4 with hydrochloric acid solution. The mixture was stirred for 24-26 hours at 20-25℃ and 500-600 r / min. After filtration, the precipitate was washed 2-4 times with deionized water and anhydrous ethanol and dried under vacuum at 60-70℃ for 1 hour to obtain modified nitrogen-doped silica sol.

[0018] Furthermore, the ratio of nitrogen-doped silica sol, tridecafluorooctyltriethoxysilane, anhydrous ethanol, and deionized water is 100-120g: 75-80mL: 200-250mL: 700-800mL.

[0019] Furthermore, the specific preparation steps of the water-based polyceramic protective coating material are as follows: Aqueous titanium dioxide sol, modified nitrogen-doped silica sol, acrylic acid solution with a neutralization degree of 40-50%, and deionized water are added to a reactor. Nitrogen gas is introduced for protection, and the mixture is stirred at 70-80℃ and 500-600 r / min for 1-2 hours. After cooling to 50-60℃, ammonium persulfate as an initiator and hydroxymethylacrylamide as a crosslinking agent are added to the reactor. Stirring is continued for 1-2 hours. The mixture is filtered, and the filter cake is washed 2-4 times with deionized water and anhydrous ethanol, respectively. The mixture is then vacuum dried at 60-70℃ for 1-2 hours to obtain an aqueous polyceramic protective coating material.

[0020] Furthermore, the ratio of aqueous titanium dioxide sol, modified nitrogen-doped silica sol, acrylic acid solution, deionized water, ammonium persulfate, and hydroxymethylacrylamide is 70-80g: 35-40g: 100-120mL: 2-3L: 2-3g: 1-2g.

[0021] Furthermore, for the acrylic acid solution with a neutralization degree of 50-60%, a sodium hydroxide solution with a mass fraction of 5-10% is used as a neutralizing agent. During the neutralization process, the target pH value of the system is controlled to be 6.0-7.5, and the conductivity is maintained at 1000-2000 μS / cm.

[0022] The beneficial effects of this invention are as follows: The water-based polyceramic protective coating material prepared by this invention can be coated on the surface of kitchen utensils and cured at low temperature to form a dense ceramic film layer, possessing superhydrophobicity and photocatalytic self-cleaning ability. The water-based polyceramic protective coating of this invention uses polyacrylic acid as an organic flexible chain segment, which is cross-linked with water-based titanium dioxide sol and modified nitrogen-doped silica sol to form a three-dimensional cross-linked interpenetrating network. The water-based titanium dioxide sol contains titanium dioxide, which can endow the coating with photocatalytic self-cleaning properties and antibacterial properties. In the modified nitrogen-doped silica sol, urea is used as a nitrogen source and mixed with graphite micropowder. Under the high diffusivity and permeability of supercritical carbon dioxide, urea molecules can be carried deep into the pores and interlayers of graphite micropowder, solving the problem that nitrogen elements in traditional doping only remain on the surface. The uniform doping of nitrogen and grafting with tridecafluorooctyltriethoxysilane can solve the problem that the original graphite is highly hydrophobic and difficult to disperse in an aqueous system. At the same time, nitrogen doping can improve the conductivity of graphite, which is beneficial to the antistatic and mechanical strength of the coating. The aqueous titanium dioxide sol and nitrogen-doped silicon sol of the present invention contain both inorganic components, titanium dioxide and silicon dioxide. The two inorganic components can disperse stress by generating sliding, thereby improving the mechanical strength of the coating. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1: A method for preparing a water-based polyceramic protective coating material, comprising the following steps: S1: Add 50 mL of 0.1 mol / L titanium oxysulfate aqueous solution and 270 mL of 50% ammonia aqueous solution to the reactor. Stir for 20 min at 20℃ and 500 r / min. Filter and wash the filter cake twice with deionized water and anhydrous ethanol until neutral. Dry under vacuum at 60℃ for 1 h to obtain metatitanic acid precipitate. Add 20 g of metatitanic acid precipitate and 80 mL of 20% hydrogen peroxide to the reactor. Stir for 20 min at 20℃ and 500 r / min. Then add 50 mL of deionized water and 15 mL of 1% isopropanol. Irradiate under a UV lamp with a center wavelength of 254 nm and continue stirring for 4 h to obtain aqueous titanium dioxide sol.

[0025] S2: Add 50g of graphitized anthracite powder with an average particle size of 6μm, 1g of polyethylene glycol and 20mL of 3% urea solution to a high-pressure reactor. Stir for 20min at 30℃ and 500r / min. Then pump 12mL of liquid carbon dioxide into the reactor to make the carbon dioxide pressure in the reactor reach 35MPa. Maintain for 1h, then remove the carbon dioxide. Repeat the operation 4 times. Then heat to 200℃ and continue stirring for 2h. Allow to cool naturally to room temperature to obtain a nitrogen-doped graphite powder solution.

[0026] S3: Add 80 mL of 1.8 g / L tetraethyl orthosilicate solution, 120 mL of deionized water and 5 mL of 0.2 mol / L dilute hydrochloric acid to the reaction vessel, stir for 20 min at 20 °C and 500 r / min, then add 70 mL of nitrogen-doped graphite powder solution, continue stirring and aging for 1 h to obtain nitrogen-doped silica sol.

[0027] S4: Add 100g of nitrogen-doped silica sol, 75mL of tridecafluorooctyltriethoxysilane, 200mL of anhydrous ethanol and 700mL of deionized water to a reaction vessel, adjust the pH value to 3 with hydrochloric acid solution, stir for 24h at 20℃ and 500r / min, filter, wash the precipitate twice with deionized water and anhydrous ethanol, and dry under vacuum at 60℃ for 1h to obtain modified nitrogen-doped silica sol.

[0028] S5: Add 70g of aqueous titanium dioxide sol, 35g of modified nitrogen-doped silica sol, 100mL of acrylic acid solution with a neutralization degree of 40% and 2L of deionized water to a reactor, purge with nitrogen for protection, and stir at 70℃ and 500r / min for 1h. Cool to 50℃, add 2g of ammonium persulfate as an initiator and 1g of hydroxymethylacrylamide as a crosslinking agent to the reactor, continue stirring for 1h, filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and vacuum dry at 60℃ for 1h to obtain an aqueous polyceramic protective coating material containing an organic-inorganic composite interpenetrating network.

[0029] Example 2: A method for preparing a water-based polyceramic protective coating material, comprising the following steps: S1: Add 55 mL of 0.15 mol / L titanium oxysulfate aqueous solution and 275 mL of 55% ammonia aqueous solution to the reactor. Stir for 30 min at 22.5℃ and 550 r / min. Filter and wash the filter cake three times with deionized water and anhydrous ethanol until neutral. Vacuum dry at 65℃ for 1.5 h to obtain metatitanic acid precipitate. Add 25 g of metatitanic acid precipitate and 85 mL of 25% hydrogen peroxide to the reactor. Stir for 30 min at 22.5℃ and 550 r / min. Then add 55 mL of deionized water and 17.5 mL of 1.5% isopropanol. Irradiate under a UV lamp with a center wavelength of 254 nm and continue stirring for 4.5 h to obtain aqueous titanium dioxide sol.

[0030] S2: 55g of graphitized anthracite powder with an average particle size of 7μm, 1.2g of polyethylene glycol, and 22.5mL of urea solution with a mass fraction of 3.5% were added to a high-pressure reactor. The mixture was stirred at 32.5℃ and 550r / min for 30min. Then, 13mL of liquid carbon dioxide was pumped into the reactor to bring the carbon dioxide pressure inside the reactor to 37.5MPa. This pressure was maintained for 1.5h, and the carbon dioxide was discharged. This process was repeated 4.5 times. The mixture was then heated to 225℃ and stirred for another 2.5h. After naturally cooling to room temperature, a nitrogen-doped graphite powder solution was obtained.

[0031] S3: Add 85 mL of 1.9 g / L tetraethyl orthosilicate solution, 130 mL of deionized water and 6.5 mL of 0.3 mol / L dilute hydrochloric acid to the reactor, stir for 30 min at 22.5 °C and 550 r / min, then add 75 mL of nitrogen-doped graphite powder solution, and continue stirring and aging for 1.5 h to obtain nitrogen-doped silica sol.

[0032] S4: 110 g of nitrogen-doped silica sol, 77.5 mL of tridecafluorooctyltriethoxysilane, 225 mL of anhydrous ethanol and 750 mL of deionized water were added to a reaction vessel. The pH value was adjusted to 3.5 with hydrochloric acid solution. The mixture was stirred at 22.5 °C and 550 r / min for 25 h. After filtration, the precipitate was washed three times with deionized water and anhydrous ethanol and dried under vacuum at 65 °C for 1 h to obtain modified nitrogen-doped silica sol.

[0033] S5: 75g of aqueous titanium dioxide sol, 37.5g of modified nitrogen-doped silica sol, 110mL of acrylic acid solution with a neutralization degree of 45% and 2.5L of deionized water were added to a reactor. Nitrogen gas was introduced for protection, and the mixture was stirred at 75℃ and 550r / min for 1.5h. After cooling to 55℃, 2.5g of ammonium persulfate as an initiator and 1.5g of hydroxymethylacrylamide as a crosslinking agent were added to the reactor. The mixture was stirred for another 1.5h. After filtration, the filter cake was washed three times with deionized water and three times with anhydrous ethanol. The cake was then vacuum dried at 65℃ for 1.5h to obtain an aqueous polyceramic protective coating material containing an organic-inorganic composite interpenetrating network.

[0034] Example 3: A method for preparing a water-based polyceramic protective coating material, comprising the following steps: S1: Add 60 mL of 0.2 mol / L titanium oxysulfate aqueous solution and 280 mL of 60% ammonia aqueous solution to the reactor. Stir for 40 min at 25 °C and 600 r / min. Filter and wash the filter cake four times with deionized water and anhydrous ethanol until neutral. Dry under vacuum at 70 °C for 2 h to obtain metatitanic acid precipitate. Add 30 g of metatitanic acid precipitate and 90 mL of 30% hydrogen peroxide to the reactor. Stir for 40 min at 25 °C and 600 r / min. Then add 60 mL of deionized water and 20 mL of 2% isopropanol. Irradiate under a UV lamp with a center wavelength of 254 nm and continue stirring for 5 h to obtain aqueous titanium dioxide sol.

[0035] S2: Add 60g of graphitized anthracite powder with an average particle size of 8μm, 2g of polyethylene glycol, and 25mL of 4% urea solution to a high-pressure reactor. Stir at 35℃ and 600r / min for 40min. Then, pump 14mL of liquid carbon dioxide into the reactor to make the carbon dioxide pressure inside the reactor reach 40MPa. Maintain this pressure for 2h, then remove the carbon dioxide. Repeat this operation 5 times. Then heat to 250℃ and continue stirring for 3h. Allow to cool naturally to room temperature to obtain a nitrogen-doped graphite powder solution.

[0036] S3: Add 90 mL of 2.0 g / L tetraethyl orthosilicate solution, 140 mL of deionized water and 8 mL of 0.4 mol / L dilute hydrochloric acid to the reactor, stir for 40 min at 25 °C and 600 r / min, then add 80 mL of nitrogen-doped graphite powder solution, continue stirring and aging for 2 h to obtain nitrogen-doped silica sol.

[0037] S4: Add 120g of nitrogen-doped silica sol, 80mL of tridecafluorooctyltriethoxysilane, 250mL of anhydrous ethanol and 800mL of deionized water to a reaction vessel, adjust the pH value to 4 with hydrochloric acid solution, stir for 26h at 25℃ and 600r / min, filter, wash the precipitate 4 times with deionized water and anhydrous ethanol, and dry under vacuum at 70℃ for 1h to obtain modified nitrogen-doped silica sol.

[0038] S5: Add 80g of aqueous titanium dioxide sol, 40g of modified nitrogen-doped silica sol, 120mL of acrylic acid solution with a neutralization degree of 50% and 3L of deionized water to a reactor, purge with nitrogen for protection, and stir at 80℃ and 600r / min for 2h. Cool to 60℃, add 3g of ammonium persulfate as an initiator and 2g of hydroxymethylacrylamide as a crosslinking agent to the reactor, continue stirring for 2h, filter, wash the filter cake four times with deionized water and anhydrous ethanol respectively, and vacuum dry at 70℃ for 2h to obtain an aqueous polyceramic protective coating material containing an organic-inorganic composite interpenetrating network.

[0039] Comparative Example 1: Based on Example 3, the aqueous titanium dioxide sol in step S5 was omitted, and the modified nitrogen-doped silicon sol was directly used as the aqueous polyceramic protective coating material.

[0040] Comparative Example 2: Based on Example 3, the modified nitrogen-doped silica sol in step S5 was omitted, and the aqueous titanium dioxide sol was directly used as the aqueous polyceramic protective coating material.

[0041] Comparative Example 3: Based on Example 3, the nitrogen-doped graphite powder solution in step S3 was replaced with graphitized anthracite powder in S2.

[0042] The water-based polyceramic protective coating materials prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, including abrasion resistance (rubber wheel friction and wear test for 10 min with 1000g weight applied at 100r / min), contact angle, hardness (tested according to GB / T6739-2006 standard test for hardness of paint and varnish by pencil method), high temperature resistance (500℃, 5h heat treatment), adhesion test (tested according to GB / T9286-1998 standard test for cross-cut adhesion of paint and varnish film), and easy cleaning (tested by wiping with a scouring pad after baking with tomato sauce at 220℃ for 15 min). The results are shown in Table 1. Table 1 As can be seen from Table 1, the wear amount, water contact angle, hardness and easy cleaning of the waterborne polyceramic protective coating materials prepared in Examples 1-3 are significantly better than those of the comparative examples. This indicates that the waterborne polyceramic protective coating prepared in this invention has superhydrophobicity and photocatalytic self-cleaning ability, and can decompose organic pollutants under ultraviolet light irradiation, thereby keeping the surface clean.

[0043] In Comparative Example 1, the aqueous titanium dioxide sol in step S5 was omitted, and the modified nitrogen-doped silicon sol was used directly as the aqueous polyceramic protective coating. The aqueous titanium dioxide sol is the core of the coating's photocatalytic function. Titanium dioxide decomposes organic pollutants under ultraviolet light. After omitting it, the coating only relies on hydrophobicity to achieve physical antifouling, but it cannot decompose the attached oil and organic matter, resulting in a decrease in easy cleaning. Titanium dioxide and silicon dioxide disperse stress through the sliding of inorganic components, thereby improving mechanical strength. Without titanium dioxide, the coating's wear resistance and hardness decrease.

[0044] In Comparative Example 2, the modified nitrogen-doped silica sol in step S5 was omitted, and the aqueous titanium dioxide sol was used directly as the aqueous polyceramic protective coating. The superhydrophobicity was completely lost. The tridecafluorooctyltriethoxysilane in the modified nitrogen-doped silica sol is the key to superhydrophobicity. After its removal, the coating only relies on the hydrophilicity of titanium dioxide. The water contact angle decreases, and oil and water can easily penetrate and adhere, making it difficult to clean instead of easy to wipe off. The silica network in the nitrogen-doped silica sol is the ceramic skeleton of the coating, providing high hardness. After its absence, the coating structure is loose, the wear rate increases, the hardness decreases, and due to insufficient density, corrosive media can easily penetrate into the substrate, leading to localized descaling. The nitrogen-doped graphite micropowder in the modified nitrogen-doped silica sol gives the coating antistatic ability. After its removal, the coating is prone to accumulating static electricity and adsorbing dust, further reducing the surface cleanliness.

[0045] In Comparative Example 3, the nitrogen-doped graphite powder solution in step S3 was replaced with graphitized anthracite powder in S2. The undoped graphite powder has no polar nitrogen-containing groups on its surface, is highly hydrophobic, and is difficult to disperse in aqueous silica sol. This leads to the formation of graphite aggregates and voids inside the coating, resulting in decreased density and increased wear. The graphite aggregates disrupt the uniform distribution of fluorosilanes on the coating surface, reducing the water contact angle. At the same time, the undoped graphite cannot form stable chemical bonds with the silica sol, resulting in a decrease in the overall strength of the coating and consequently a decrease in hardness. Nitrogen doping is the key to improving the conductivity of graphite. Undoped graphite has poor conductivity, significantly reducing the antistatic ability of the coating and making it easy to attract dust, thus turning easy cleaning into difficult cleaning.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a water-based polyceramic protective coating material, characterized in that, Includes the following steps: S1. Titanium sulfate and ammonia water react with each other through acid-base neutralization to generate metatitanic acid precipitate. Then, through hydrogen peroxide oxidation and ultraviolet irradiation, the metatitanic acid precipitate is dispersed to form an aqueous titanium dioxide sol. S2. Urea and graphitized anthracite powder are doped together, and liquid carbon dioxide is introduced into a high-pressure reactor and then heated to obtain a nitrogen-doped graphite powder solution. S3. Tetraethyl orthosilicate forms silica sol under the catalysis of dilute hydrochloric acid. The silica sol is mixed with nitrogen-doped graphite powder solution and then subjected to aging treatment to obtain nitrogen-doped silica sol. S4. Modified nitrogen-doped silica sol is obtained by hydrolyzing and condensing the hydroxyl groups of nitrogen-doped silica sol with tridecafluorooctyltriethoxysilane in ethanol solution. S5. A water-based polyceramic protective coating material is obtained by free radical polymerization of aqueous titanium dioxide sol, modified nitrogen-doped silica sol and acrylic acid solution.

2. The method for preparing a water-based polyceramic protective coating material according to claim 1, characterized in that, The mass ratio of the aqueous titanium dioxide sol to the modified nitrogen-doped silicon sol is 2:

1.

3. The method for preparing a water-based polyceramic protective coating material according to claim 1, characterized in that, The specific preparation steps of the aqueous titanium dioxide sol are as follows: A 0.1-0.2 mol / L aqueous solution of titanium oxysulfate and a 50-60% ammonia solution were added to a reaction vessel at a volume ratio of 50-60:270-280. The mixture was stirred for 20-40 minutes at 20-25°C and 500-600 rpm. After filtration, the filter cake was washed 2-4 times with deionized water and anhydrous ethanol until neutral. The cake was then vacuum dried at 60-70°C for 1-2 hours to obtain metatitanic acid precipitate. The metatitanic acid precipitate and a 20-30% hydrogen peroxide solution were added to the reaction vessel. The mixture was stirred for 20-40 minutes at 20-25°C and 500-600 rpm. Then, deionized water and a 1-2% isopropanol solution were added. The mixture was irradiated under a 254 nm UV lamp and stirred for 4-5 hours to obtain an aqueous titanium dioxide sol. The ratio of metatitanic acid precipitate, hydrogen peroxide, deionized water and isopropanol is 20-30g: 80-90mL: 50-60mL: 15-20mL.

4. The method for preparing a water-based polyceramic protective coating material according to claim 1, characterized in that, The specific preparation steps of the nitrogen-doped graphite powder solution are as follows: Graphitized anthracite powder with an average particle size of 6-8 μm, polyethylene glycol as a dispersant, and a urea solution with a mass fraction of 3-4% were added to a high-pressure reactor. The mixture was stirred for 20-40 min at 30-35℃ and 500-600 r / min. Then, liquid carbon dioxide was pumped into the reactor to bring the carbon dioxide pressure inside the reactor to 35-40 MPa. This pressure was maintained for 1-2 h, and the carbon dioxide was discharged. This process was repeated 4-5 times. The mixture was then heated to 200-250℃ and stirred for another 2-3 h. After naturally cooling to room temperature, a nitrogen-doped graphite powder solution was obtained.

5. The method for preparing a water-based polyceramic protective coating material according to claim 4, characterized in that, The ratio of graphitized anthracite powder, polyethylene glycol, urea solution, and liquid carbon dioxide is 50-60g: 1-2g: 20-25mL: 12-14mL.

6. The method for preparing a water-based polyceramic protective coating material according to claim 1, characterized in that, The specific preparation steps of the nitrogen-doped silica sol are as follows: A 1.8-2.0 g / L tetraethyl orthosilicate solution, deionized water, and 0.2-0.4 mol / L dilute hydrochloric acid were added to a reaction vessel and stirred for 20-40 minutes at 20-25 °C and 500-600 r / min. Then, a nitrogen-doped graphite powder solution was added, and the mixture was stirred and aged for 1-2 hours to obtain a nitrogen-doped silica sol.

7. The method for preparing a water-based polyceramic protective coating material according to claim 6, characterized in that, The ratio of the amount of tetraethyl orthosilicate solution, deionized water, dilute hydrochloric acid and nitrogen-doped graphite powder solution is 80-90 mL: 120-140 mL: 5-8 mL: 70-80 mL.

8. The method for preparing a water-based polyceramic protective coating material according to claim 1, characterized in that, The specific preparation steps of the modified nitrogen-doped silica sol are as follows: Nitrogen-doped silica sol, tridecafluorooctyltriethoxysilane, anhydrous ethanol and deionized water were added to a reaction vessel, the pH was adjusted to 3-4 with hydrochloric acid solution, and the mixture was stirred for 24-26 h at 20-25 ℃ and 500-600 r / min. After filtration, the precipitate was washed 2-4 times with deionized water and anhydrous ethanol, and then dried under vacuum at 60-70 ℃ for 1 h to obtain modified nitrogen-doped silica sol. The ratio of nitrogen-doped silica sol, tridecafluorooctyltriethoxysilane, anhydrous ethanol, and deionized water is 100-120g: 75-80mL: 200-250mL: 700-800mL.

9. The method for preparing a water-based polyceramic protective coating material according to claim 1, characterized in that, The specific preparation steps of the water-based polyceramic protective coating material are as follows: Aqueous titanium dioxide sol, modified nitrogen-doped silica sol, acrylic acid solution with a neutralization degree of 40-50% and deionized water are added to a reaction vessel. Nitrogen gas is introduced for protection, and the reaction is stirred at 70-80℃ and 500-600 r / min for 1-2 hours. After cooling to 50-60℃, ammonium persulfate as an initiator and hydroxymethylacrylamide as a crosslinking agent are added to the reaction vessel. Stirring is continued for 1-2 hours. The mixture is filtered, and the filter cake is washed 2-4 times with deionized water and anhydrous ethanol, respectively. The mixture is then vacuum dried at 60-70℃ for 1-2 hours to obtain an aqueous polyceramic protective coating material. The ratio of aqueous titanium dioxide sol, modified nitrogen-doped silica sol, acrylic acid solution, deionized water, ammonium persulfate, and hydroxymethylacrylamide is 70-80g:35-40g:100-120mL:2-3L:2-3g:1-2g. The acrylic acid solution with a neutralization degree of 50-60% uses a 5-10% sodium hydroxide solution as a neutralizing agent. During the neutralization process, the target pH value of the system is controlled at 6.0-7.5, and the conductivity is maintained at 1000-2000μS / cm.

10. A water-based polyceramic protective coating material, characterized in that, It is prepared by the preparation method described in any one of claims 1-9.

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