Anti-fouling outer coating for kitchen ware and preparation method of anti-fouling outer coating

Abstract

The invention relates to the technical field of kitchenware surface treatment. The kitchenware surface treatment agent is prepared from the following components: organic silicon modified acrylic resin, perfluoropolyether modified siloxane, nitrogen-doped titanium dioxide nanotubes, nano silicon dioxide aerogel particles and high-temperature-resistant pigments and fillers, the coating has passive anti-fouling and active self-cleaning functions at the same time, passive anti-fouling is achieved through low surface energy given by perfluoropolyether modified siloxane, and active self-cleaning is achieved through visible light catalysis of nitrogen-doped titanium dioxide nanotubes. According to the kitchen ware anti-fouling outer coating and the preparation method thereof, a low-surface-energy coating is formed through the synergistic effect of the organic silicon modified acrylic resin and the perfluoropolyether modified siloxane, and the visible light catalytic decomposition capacity of the nitrogen-doped titanium dioxide nanotubes is combined; the problems that an existing coating is insufficient in anti-fouling performance, lacks a self-cleaning function and is poor in high-temperature stability are effectively solved, and the anti-fouling coating has the advantages that the anti-fouling durability is remarkably improved, the service life is prolonged, and the surface hardness is enhanced.

Description

Technical Field

[0001] This application relates to the field of kitchenware surface treatment technology, and more specifically, to a stain-resistant outer coating for kitchenware and its preparation method. Background Technology

[0002] The outer surfaces of cookware such as pots and pans are easily contaminated by spilled soups, oil, and other substances during use. These contaminants carbonize and sinter at high temperatures, forming stubborn stains that are difficult to remove, severely impacting both appearance and cleaning efficiency. Currently, most cookware coatings on the market use ordinary silicone resins or high-temperature paints, primarily serving decorative and rust-preventive purposes, with limited stain resistance.

[0003] Existing technologies have the following shortcomings: In terms of passive stain resistance, most methods reduce stain adhesion by increasing surface smoothness. However, this method only delays stain adhesion; once contaminants adhere, they are still difficult to clean, especially stubborn stains that have undergone high-temperature carbonization. Regarding scratch resistance, existing organic coatings generally have low hardness, making them prone to damage when cleaned with hard objects like steel wool, thus accelerating coating failure. More importantly, existing coatings completely lack self-cleaning capabilities and cannot actively decompose adhered organic contaminants, relying solely on physical cleaning methods. Furthermore, ordinary organic coatings are prone to yellowing and chalking under prolonged high-temperature environments, severely affecting their lifespan and aesthetics.

[0004] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0005] The purpose of this application is to provide a stain-resistant outer coating for kitchenware and its preparation method, which has the advantages of simultaneously achieving passive stain resistance and active self-cleaning, improving high-temperature resistance and service life.

[0006] This application provides an anti-fouling outer coating for kitchenware, the technical solution of which is as follows: An anti-fouling outer coating for kitchenware, characterized in that the raw materials include organosilicon-modified acrylic resin, perfluoropolyether-modified siloxane, nitrogen-doped titanium dioxide nanotubes, nano-silica aerogel particles, and high-temperature resistant pigments and fillers; the coating has both passive anti-fouling and active self-cleaning functions, the passive anti-fouling is achieved by the low surface energy imparted by the perfluoropolyether-modified siloxane, and the active self-cleaning is achieved by the visible light photocatalytic effect of nitrogen-doped titanium dioxide nanotubes.

[0007] Furthermore, this application also proposes that, by mass parts, the content of each raw material component is as follows: 40-60 parts of organosilicon modified acrylic resin, 10-20 parts of perfluoropolyether modified siloxane, 5-15 parts of nitrogen-doped titanium dioxide nanotubes, 5-10 parts of nano-silica aerogel particles, and 10-20 parts of high-temperature resistant pigments and fillers.

[0008] Furthermore, this application also proposes that nitrogen-doped titanium dioxide nanotubes undergo surface modification treatment with a silane coupling agent; the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane (KH-570).

[0009] Furthermore, this application also proposes that the raw materials also include a dispersant and a leveling agent, with the total mass fraction of the dispersant and leveling agent being 1-3 parts; the dispersant is BYK-163, and the leveling agent is an acrylate leveling agent.

[0010] Furthermore, this application also proposes that the coating has a water contact angle >110°, an oil contact angle (using soybean oil as the test medium) >80°, a pencil hardness of 4-6H, and can be used for a long time in high-temperature environments above 250°C without discoloration or chalking.

[0011] Furthermore, this application also proposes a method for preparing an antifouling outer coating comprising the following steps: a) surface modification treatment of nitrogen-doped titanium dioxide nanotubes to obtain modified nitrogen-doped titanium dioxide nanotubes; b) mixing organosilicon-modified acrylic resin, perfluoropolyether-modified siloxane, and a portion of solvent, and stirring at high speed to obtain a premix; c) adding modified nitrogen-doped titanium dioxide nanotubes, nano-silica aerogel particles, and high-temperature resistant pigments and fillers to the premix obtained in step b), and dispersing at high speed to obtain a uniform slurry; d) adding the remaining solvent, dispersant, and leveling agent to the slurry obtained in step c), adjusting the coating viscosity to 60-80s (Ford cup 4), and filtering to obtain an antifouling outer coating.

[0012] Furthermore, this application also proposes that in step c), the high-speed dispersion is carried out using a high-speed shear mill or a ball mill, with a dispersion speed of 2000-3000 rpm and a dispersion time of 1-2 hours, resulting in a slurry fineness of ≤25μm after dispersion.

[0013] Furthermore, this application also proposes a coating and curing step: applying the coating obtained in step d) to the outer surface of the pretreated kitchenware substrate by electrostatic spraying, and curing it at 180-200℃ for 20-30 minutes to form an anti-fouling outer coating.

[0014] Furthermore, this application also proposes that the specific process of surface modification treatment in step a) is as follows: nitrogen-doped titanium dioxide nanotubes are mixed and reacted with silane coupling agent KH-570 in an ethanol solution, and then dried to obtain modified nitrogen-doped titanium dioxide nanotubes; the mass fraction of ethanol in the ethanol solution is 70%-90%.

[0015] Furthermore, this application also proposes that the high-speed stirring speed in step b) is 1000-1500 rpm and the stirring time is 30 minutes; the solvent is propylene glycol methyl ether, and the solvent added in step b) accounts for 50% of the total mass of the solvent.

[0016] As can be seen from the above, the anti-fouling outer coating for kitchenware and its preparation method provided in this application form a low surface energy coating through the synergistic effect of organosilicon-modified acrylic resin and perfluoropolyether-modified siloxane. Combined with the visible light photocatalytic decomposition ability of nitrogen-doped titanium dioxide nanotubes, it effectively solves the problems of insufficient anti-fouling performance, lack of self-cleaning function and poor high temperature stability of existing coatings. It has the advantages of significantly improving anti-fouling durability, extending service life and enhancing surface hardness. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In existing technologies, the outer surfaces of cookware such as pots and pans are easily contaminated by spilled soup and oil during use. These contaminants carbonize at high temperatures, forming stubborn stains. Current cookware coatings mostly use ordinary silicone resins or high-temperature paints, whose passive stain resistance relies on surface smoothness; however, once contaminants adhere, they are difficult to remove. Insufficient coating hardness makes them easily scratched by hard objects during cleaning, and they lack the ability to actively decompose contaminants, easily leading to yellowing and powdering under prolonged high temperatures.

[0019] To address the aforementioned problems, the inventors discovered that simply increasing surface smoothness is insufficient to solve the cleaning challenge after contaminant adhesion; an active decomposition mechanism is needed. Analysis of photocatalytic materials revealed that nitrogen-doped titanium dioxide nanotubes exhibit catalytic activity under visible light, but their dispersion stability within the coating needs to be addressed. Simultaneously, the selection of low surface energy materials must consider high-temperature resistance; the molecular structure of perfluoropolyether-modified siloxanes meets these requirements. Regarding the matrix material, organosilicon-modified acrylic resin ensures both coating adhesion and high-temperature resistance. While introducing nano-silica aerogel particles to enhance coating hardness, it is crucial to balance their synergistic effect with pigments and fillers.

[0020] Therefore, this application proposes an anti-fouling coating for kitchenware, the raw materials of which include silicone-modified acrylic resin, perfluoropolyether-modified siloxane, nitrogen-doped titanium dioxide nanotubes, nano-silica aerogel particles, and high-temperature resistant pigments and fillers. This coating possesses both passive anti-fouling and active self-cleaning functions. Passive anti-fouling is achieved through the low surface energy imparted by the perfluoropolyether-modified siloxane, while active self-cleaning is achieved through the visible light photocatalytic effect of the nitrogen-doped titanium dioxide nanotubes.

[0021] Among them, organosilicon-modified acrylic resin refers to a polymer material in which organosilicon segments are introduced into the acrylic resin skeleton through chemical grafting, and it can be prepared by free radical polymerization. This material, as a coating matrix, improves heat resistance while maintaining the film-forming properties of acrylic resin. Perfluoropolyether-modified siloxane refers to a compound containing perfluoropolyether segments and a siloxane structure, and it can be prepared by hydrolysis-condensation reaction. Its fluorocarbon segments reduce the surface energy of the coating and inhibit the initial adhesion of contaminants. Nitrogen-doped titanium dioxide nanotubes refer to tubular nanomaterials prepared by hydrothermal methods; after nitrogen doping, the visible light response range is extended to the 400-550 nm wavelength band. Nano-silica aerogel particles refer to silica particles with a three-dimensional nanoporous structure, which can be prepared by the sol-gel method; their porous structure improves the mechanical strength of the coating. High-temperature resistant pigments and fillers refer to inorganic pigments mainly composed of metal oxides, such as alumina or zirconium oxide, which maintain chemical stability at high temperatures.

[0022] Specifically, organosilicon-modified acrylic resin forms a continuous phase as the coating framework, while perfluoropolyether-modified siloxane migrates to the coating surface to form a low surface energy layer. Nitrogen-doped titanium dioxide nanotubes are uniformly dispersed in the matrix, generating electron-hole pairs under visible light irradiation, decomposing organic matter attached to the coating surface. Nano-sized silica aerogel particles fill the resin matrix, enhancing coating hardness through nanoscale interlocking effects. High-temperature resistant pigments and fillers form a dense structure with the matrix material, inhibiting thermal decomposition reactions at high temperatures. The components interact at the interfaces to form a synergistic system: a passive antifouling layer reduces contaminant adhesion, an active catalytic layer decomposes residual contaminants, rigid fillers improve scratch resistance, and inorganic components ensure high-temperature stability.

[0023] Compared to existing technologies, traditional coatings rely solely on a single physical barrier for fouling resistance, while this solution utilizes a synergistic effect of chemical catalysis and physical protection. Existing perfluorinated compounds often employ short-chain structures, resulting in insufficient temperature resistance; this solution uses perfluorinated polyether-modified siloxanes to improve thermal stability while maintaining low surface energy. Compared to unmodified titanium dioxide, nitrogen doping activates its catalytic activity even under indoor lighting conditions. The introduction of nano-silica aerogel particles avoids increased coating brittleness while enhancing hardness, overcoming the problem of decreased flexibility caused by traditional hardening fillers.

[0024] Through the above technical solutions, this application achieves multiple performance improvements in the outer coating of kitchenware. The low surface energy characteristic makes it difficult for liquid contaminants to wet the coating surface; visible light photocatalysis decomposes adhered oil stains and other organic matter; the nano-reinforced structure allows the coating to withstand scrubbing with steel wool without damage; and the inorganic high-temperature resistant components ensure that the coating does not fail during long-term use in high-temperature environments such as ovens. The various functional components form a spatial distribution gradient within the coating; the surface-enriched perfluoropolyether layer provides immediate anti-fouling capabilities; the internal photocatalyst continuously decomposes penetrating contaminants; and the rigid filler maintains the structural integrity of the coating.

[0025] This application further proposes that, by weight, the content of each raw material component is as follows: 40-60 parts of organosilicon modified acrylic resin, 10-20 parts of perfluoropolyether modified siloxane, 5-15 parts of nitrogen-doped titanium dioxide nanotubes, 5-10 parts of nano-silica aerogel particles, and 10-20 parts of high-temperature resistant pigments and fillers.

[0026] Specifically, the amount of silicone-modified acrylic resin is controlled within the range of 40-60 parts. This ensures the critical amount required for the formation of a continuous and dense film in the resin matrix while reserving dispersion space for other functional components. When the amount is less than 40 parts, the integrity of the coating film is compromised, leading to decreased adhesion. When the amount exceeds 60 parts, the viscosity of the system increases, affecting the dispersion of nanoparticles. A 10-20 part ratio of perfluoropolyether-modified siloxane forms a rich layer on the coating surface through fluorocarbon segments, achieving low surface energy characteristics. This amount ensures a passive antifouling effect with a contact angle >110° while avoiding phase separation problems caused by excessive addition. Nitrogen-doped titanium dioxide nanotubes are uniformly dispersed in the resin matrix at an addition amount of 5-15 parts. Under visible light excitation, they generate hydroxyl radicals to decompose organic pollutants. The lower limit of this amount ensures sufficient photocatalytic active sites per unit area, while the upper limit prevents the decrease in light transmittance caused by nanotube aggregation. Nano-sized silica aerogel particles are introduced at a ratio of 5-10 parts. Their porous structure absorbs thermal stress and enhances coating hardness. This dosage increases mechanical strength without compromising coating flexibility. High-temperature resistant pigments and fillers are added synergistically with functional components at a ratio of 10-20 parts. This provides dimensional stability under high-temperature conditions and optimizes the coating's coefficient of thermal expansion through filler particle size distribution.

[0027] This application further proposes a surface modification treatment of nitrogen-doped titanium dioxide nanotubes with a silane coupling agent, wherein the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane. Nitrogen-doped titanium dioxide nanotubes refer to titanium dioxide nanotube materials modified by nitrogen doping, specifically prepared by a hydrothermal method. Their tubular structure increases specific surface area and enhances visible light absorption, serving as a photocatalytically active component in coatings. The silane coupling agent γ-methacryloyloxypropyltrimethoxysilane refers to a bifunctional compound containing methoxy and methacryloxy groups. Ethanol solution is used as the reaction medium. The methoxy group forms a chemical bond with the hydroxyl groups on the nanotube surface through hydrolysis, while the methacryloxy group crosslinks with the resin matrix, thus establishing a chemical bridge between the nanotubes and the resin. Specifically, nitrogen-doped titanium dioxide nanotubes react with a silane coupling agent in an ethanol solution. The silanol groups generated from the hydrolysis of methoxy groups undergo a condensation reaction with the hydroxyl groups on the nanotube surface, forming stable Si-O-Ti chemical bonds. Simultaneously, the methacryloyloxy groups at the ends of the coupling agent chemically crosslink with the active groups of the organosilicon-modified acrylic resin during coating curing. This dual-action mechanism forms an organic coating layer on the nanotube surface, reducing surface energy differences, promoting uniform dispersion of nanotubes in the resin matrix, and enhancing the interfacial bonding strength between the nanotubes and the matrix through chemical bonding. This application further proposes adding a dispersant and a leveling agent to the coating system, wherein the total mass fraction of the dispersant and the leveling agent is 1-3 parts, the dispersant is BYK-163, and the leveling agent is an acrylic leveling agent. The dispersant refers to an additive that improves the dispersibility of nanomaterials in a resin matrix. Specifically, BYK-163 with anchoring groups can be used; its polar groups in its molecular structure can adsorb onto the surface of nanoparticles, preventing particle aggregation through steric hindrance. The leveling agent refers to an additive that reduces the surface tension of the coating. Specifically, acrylate leveling agents can be used. They adjust the surface tension gradient of the coating during curing, promoting the formation of a smooth surface. The total mass fraction of dispersant and leveling agent is limited to 1-3 parts to ensure the dispersion stability of nanomaterials and the leveling properties of the coating, while avoiding excessive addition that could degrade the mechanical properties of the resin matrix. Specifically, the BYK-163 dispersant forms a stable steric hindrance layer by chemically adsorbing onto the surface of nitrogen-doped titanium dioxide nanotubes and nano-silica aerogel particles through anchoring groups on its molecular chain, effectively inhibiting secondary agglomeration of nanoparticles. The acrylate leveling agent reduces the surface tension of the coating, allowing it to spread evenly during curing and eliminating orange peel or pinhole defects. The total amount of dispersant and leveling agent is controlled within the range of 1-3 parts to meet the dispersion requirements of nanomaterials while avoiding interference from excessive additives on the resin cross-linking structure, ensuring that the final coating forms a dense and uniform microstructure. This application further proposes that the coating has a water contact angle greater than 110 degrees, an oil contact angle greater than 80 degrees with soybean oil as the test medium, and a pencil hardness of 4 to 6H. It can be used for a long time in high-temperature environments above 250 degrees Celsius without discoloration or chalking. The water contact angle refers to the contact angle formed by a liquid on a solid surface. This can be achieved by adjusting the addition ratio of perfluoropolyether-modified siloxane, reducing surface energy and thus decreasing the adhesion of water-based contaminants. The oil contact angle refers to the contact angle formed by oily liquids on a solid surface, achieved by optimizing the surface modification process of nitrogen-doped titanium dioxide nanotubes. This prevents oil penetration and enhances oil resistance. Pencil hardness refers to the coating surface's resistance to scratches from hard objects, achieved by controlling the particle size distribution of nano-silica aerogel particles. This improves the coating's mechanical strength to prevent scratches during cleaning. High-temperature stability refers to the coating's ability to maintain its physicochemical properties at sustained high temperatures, achieved through the synergistic effect of selecting high-temperature resistant pigments and fillers with silicone-modified acrylic resin. This prevents discoloration or chalking caused by thermal decomposition. Specifically, the superhydrophobic property reduces surface energy, making it difficult for water droplets to wet the surface, thereby reducing the adhesion of water-based contaminants; the anti-adhesion ability of oil contaminants is achieved by optimizing the surface chemical composition, preventing oil from penetrating into the coating; high mechanical strength is achieved through the composite structure of inorganic nanoparticles and resin matrix, maintaining the integrity of the coating to ensure long-term anti-fouling performance; and high temperature resistance is achieved through the combination of thermally stable materials, ensuring that the coating does not undergo thermal degradation at extreme temperatures. This application further proposes a method for preparing an outer coating for kitchenware that combines passive anti-fouling, active self-cleaning, high hardness, and high temperature resistance. The method includes the following steps: surface modification treatment of nitrogen-doped titanium dioxide nanotubes to obtain modified nanotubes; mixing organosilicon-modified acrylic resin, perfluoropolyether-modified siloxane, and a portion of solvent with high-speed stirring to form a premix; adding modified nanotubes, nano-silica aerogel particles, and high-temperature resistant pigments and fillers to the premix and dispersing them at high speed to form a uniform slurry; adding the remaining solvent and additives to the slurry to adjust the viscosity and then filtering to obtain the coating.

[0028] Surface modification refers to the surface modification of nanotubes using silane coupling agents, specifically γ-methacryloyloxypropyltrimethoxysilane reacted in an ethanol solution. This treatment enhances the dispersion stability of nanotubes in the resin matrix and prevents agglomeration that leads to a decrease in catalytic activity. High-speed dispersion refers to using mechanical force to uniformly distribute solid particles in a liquid medium, specifically achieved using a high-speed shear mill or ball mill. This process helps aerogel microparticles and pigments / fillers form an interpenetrating network structure. Gradient addition refers to the phased addition of different components, specifically by first mixing the resin with fluorosilicone materials before introducing the functional filler. This method ensures the uniform distribution of low surface energy materials and maintains the dispersion of nanoparticles.

[0029] Specifically, the surface-modified nanotubes fully integrate with the resin matrix in the premix, and the organic segments grafted onto their surfaces chemically bond with the resin molecules, forming a stable dispersion system. The premix formed by high-speed stirring provides a uniform carrier for subsequent filler addition, and the perfluoropolyether-modified siloxane forms continuously distributed low surface energy regions in the resin phase. When functional fillers are added stepwise, the photocatalytic active sites of the modified nanotubes are completely preserved, and the aerogel particles are uniformly embedded in the resin network through high-speed dispersion, jointly constructing a supporting framework with high-temperature resistant pigments and fillers. In the viscosity adjustment stage, the amount of solvent added is controlled to achieve suitable rheological properties for spraying and to avoid filler sedimentation during storage.

[0030] Compared to existing technologies, traditional coating preparation processes typically employ a one-time mixing method, making it difficult to coordinate the dispersion requirements of different functional materials. Existing methods do not perform surface modification treatment when introducing photocatalytic materials, leading to nanoparticle agglomeration and affecting catalytic efficiency. Conventional processes are prone to phase separation when mixing high-temperature fillers with low surface energy components, failing to form a stable composite structure. This method solves the technical challenge of synergistic dispersion of multiple components through a stepwise processing and gradient addition strategy.

[0031] Through the above technical solutions, this application achieves effective dispersion of photocatalytic components in the coating, ensuring full exposure of catalytic active sites; constructs a surface structure combining low surface energy and high hardness, making it difficult for pollutants to adhere and easy to be decomposed by photocatalysis; forms an interpenetrating network of high-temperature resistant filler and resin matrix, improving the thermal stability and mechanical strength of the coating; and obtains a stable coating system through staged solvent control, meeting the requirements of industrial coating processes.

[0032] This application further proposes that in step c), a high-speed shearing machine or ball mill be used for high-speed dispersion, with the dispersion speed controlled in the range of 2000-3000 rpm, the dispersion time controlled in the range of 1-2 hours, and the fineness of the dispersed slurry controlled below 25 μm. High-speed shearing machines are devices that disperse materials by generating high shear forces between the rotor and stator. Specifically, they can employ shear heads with multi-stage toothed structures to break down nanoparticle agglomerates through mechanical shearing. Ball mills utilize the collision and friction between grinding media and materials to achieve dispersion. Zirconia ceramic balls are typically used as grinding media, and the energy generated by the collisions breaks down nanoparticle agglomerates. The dispersion speed of 2000-3000 rpm refers to the range of mechanical movement speed during equipment operation. This can be achieved using a variable frequency speed control motor in conjunction with a speed sensor. This range provides sufficient kinetic energy to deagglomerate while avoiding excessive speed that could damage the nanostructure. The dispersion time of 1-2 hours refers to the continuous processing time of the material in the equipment. This can be achieved using a timer control system in conjunction with a temperature monitoring device, ensuring effective dispersion while avoiding excessive energy consumption. The slurry fineness of ≤25μm refers to the maximum particle size of solid particles in the slurry. This can be achieved using a laser particle size analyzer in conjunction with an online sampling system, ensuring uniform distribution of nanomaterials in the resin through particle size control. Specifically, in the preparation of the coating slurry, a high-speed shear mill or ball mill is selected as the dispersion equipment, utilizing their unique mechanical action to disperse the nanomaterials. When using a high-speed shear mill, the high-frequency shear flow field formed between the rotor and stator generates a strong turbulent effect, causing the agglomerated nanoparticles to gradually dissociate under shear stress. When using a ball mill, the collision and friction between the grinding media and the material generates sufficient energy input, breaking the van der Waals forces between nanoparticles through physical impact. By controlling the rotation speed within the range of 2000-3000 rpm, sufficient energy input for deagglomeration is ensured while avoiding local overheating caused by excessively high rotation speeds. A dispersion time of 1-2 hours ensures sufficient wetting and stable dispersion of the nanomaterials in the resin matrix. Combined with online fineness detection, the final slurry fineness is controlled below 25 μm, forming a uniform and stable dispersion system. This application further proposes a coating and curing step, in which the coating is electrostatically sprayed onto the outer surface of the pretreated kitchenware substrate and cured at 180-200℃ for 20-30 minutes to form an anti-fouling outer coating. Electrostatic spraying refers to a coating process that uses a high-voltage electrostatic field to charge paint particles and uniformly adsorb them onto the substrate surface. Specifically, this can be achieved using a high-voltage electrostatic generator in conjunction with a rotating atomizing spray gun. This process enables the coating containing nanomaterials to form a dense and uniform film. The pre-treated outer surface of the kitchenware substrate refers to a metal surface that has undergone degreasing, sandblasting, and phosphating treatment. This can be achieved through alkaline degreasing agent cleaning and zinc phosphate conversion film treatment, which enhances the mechanical bonding between the coating and the substrate. The 180-200℃ curing temperature refers to the heat treatment range required for the coating's cross-linking reaction. This can be achieved using a hot air circulating oven. This temperature range allows for the resin cross-linking reaction to complete while avoiding the thermal decomposition of the perfluoropolyether-modified siloxane. The 20-30 minute curing time refers to the continuous heat treatment duration required for the coating to form a three-dimensional network structure. This can be achieved through a temperature-time interlocking control system, ensuring the integrity of the nano-titanium dioxide crystal structure. Specifically, the electrostatic spraying process creates a uniform coating layer for the paint containing nano-titanium dioxide and nano-aerogel. The microscopic roughness of the pretreated substrate surface enhances coating adhesion. The curing temperature is controlled above the glass transition temperature of the silicone resin, promoting full extension and cross-linking of the resin molecular chains while avoiding exceeding the thermal decomposition critical temperature of the perfluoropolyether-modified siloxane. The curing time is set to the plateau region of the cross-linking reaction kinetic curve, ensuring complete curing of the coating while preventing crystal transformation of nitrogen-doped titanium dioxide nanotubes due to prolonged high-temperature treatment. Under this temperature-time combination, the nano-silica aerogel particles form an interpenetrating network structure with the resin matrix, enhancing the mechanical strength of the coating. This application further proposes to mix nitrogen-doped titanium dioxide nanotubes with silane coupling agent KH-570 in an ethanol solution and then dry them to obtain modified nitrogen-doped titanium dioxide nanotubes; the mass fraction of ethanol in the ethanol solution is 70%-90%.

[0033] The mass fraction of the ethanol solution refers to the mass percentage of ethanol in the mixed solvent, which can be achieved by adjusting the ratio of ethanol to water. This concentration range ensures effective hydrolysis of the silane coupling agent to form active silanol groups, while avoiding excessive water leading to nanoparticle aggregation. The silane coupling agent KH-570 is a trimethoxysilane compound containing a methacryloyloxy functional group. The siloxane groups in its molecule can chemically bond with the hydroxyl groups on the nanotube surface, and the organic functional groups can form covalent bonds with the resin matrix, thereby enhancing the interfacial bonding between inorganic nanomaterials and organic resins. Surface modification refers to the process of grafting an organic molecular layer onto the surface of nanomaterials through a chemical reaction. Specifically, a combination of mechanical stirring and ultrasonic dispersion can be used to achieve sufficient contact between the nanoparticles and the coupling agent.

[0034] Specifically, in an ethanol medium, the silane coupling agent molecules first hydrolyze to generate active silanol groups, which then form Si-O-Ti chemical bonds with the hydroxyl groups on the surface of nitrogen-doped titanium dioxide nanotubes through a condensation reaction. During the reaction, the methacryloxy functional groups of KH-570 extend outward, forming an organic coating layer on the nanotube surface. This organic layer has a similar polarity to the silicone-modified acrylic resin in the subsequent coating system, allowing the modified nanotubes to be uniformly dispersed in the resin matrix. By controlling the ethanol concentration, the appropriate amount of water required for the hydrolysis of the coupling agent is ensured, while avoiding excessive water molecules that could cause secondary agglomeration of the nanotubes. Drying removes residual solvent and prevents the nanoparticles from clumping during storage.

[0035] This application further proposes that, in preparing the antifouling outer coating premix, propylene glycol methyl ether is used as a solvent, and in step b, the amount of solvent added is controlled to 50% of the total mass, while the mixture is stirred at a high speed of 1000-1500 rpm for 30 minutes.

[0036] The high-speed stirring rotation range refers to the range of mechanical shear force intensity generated during the operation of the mixing equipment. This can be achieved by adjusting the angular velocity of the stirring paddle using a variable frequency motor. This parameter range ensures sufficient wetting of the resin and solvent while preventing molecular chain breakage due to excessive shear force. Propylene glycol methyl ether, as a solvent, refers to an ether compound with moderate volatility and strong dissolving power. This can be achieved by adding industrial-grade propylene glycol methyl ether. The ether bonds and hydroxyl groups in its molecular structure can simultaneously form hydrogen bonds with the polar groups in the resin. The 50% solvent content means that only half of the predetermined total solvent volume is added at the initial stage of mixing. This can be achieved through staged, quantitative addition. This proportion design ensures the premix has a suitable initial viscosity, allowing for adjustment space when adding more solvent later.

[0037] Specifically, in the mixing process of silicone-modified acrylic resin and perfluoropolyether-modified siloxane, limiting the lower limit of the stirring speed ensures that the resin molecular chains are fully extended in the solvent, while the upper limit prevents high-speed shearing from damaging the microphase separation structure of the fluorosilicone polymer. A continuous stirring time of 30 minutes allows the two resins to achieve uniform dispersion at the molecular level, forming a stable premixed liquid matrix. When propylene glycol methyl ether is chosen as the solvent, its moderate boiling point reduces volatilization losses during mixing, and its amphiphilic molecular structure helps reduce interfacial tension between resins. In the process of adding solvent in two stages, the initial addition of 50% of the solvent creates a fluid mixture system, which meets the mass transfer requirements of high-speed stirring while avoiding excessive solvent leading to too low a resin concentration and affecting dispersion efficiency.

[0038] Example 1 1) Take the following materials: 50 parts of organosilicon-modified acrylic resin, 15 parts of perfluoropolyether-modified siloxane, 10 parts of nitrogen-doped titanium dioxide nanotubes, 8 parts of nano-silica aerogel particles, 15 parts of high-temperature resistant pigments and fillers, 1.5 parts of dispersant (BYK-163), 1.5 parts of leveling agent (acrylate), and 20 parts of solvent (propylene glycol methyl ether).

[0039] 2) Ten parts of nitrogen-doped titanium dioxide nanotubes were added to an 8% (w / w) dilute nitric acid solution and ultrasonically cleaned at 300W for 30 minutes to remove the template agent. The nanotubes were then centrifuged and washed with deionized water (8000 rpm, 10 minutes) until the pH of the filtrate was 7.0. The nanotubes were then vacuum dried at 80℃ for 4 hours. 0.4 parts of KH-570, which accounted for 4% of the mass of the nitrogen-doped titanium dioxide nanotubes, were weighed and dissolved in 10 mL of an 80% (w / w) ethanol solution. The solution was magnetically stirred for 15 minutes until complete hydrolysis. The pretreated nitrogen-doped titanium dioxide nanotubes were added to the above hydrolysis solution at a solid-liquid ratio of 1:10 (g:mL). The solution was stirred in a constant temperature water bath at 65℃ for 2.5 hours (400 rpm). The product was centrifuged and washed three times with anhydrous ethanol. The product was then dried in an oven at 110℃ for 2 hours to obtain modified nitrogen-doped titanium dioxide nanotubes.

[0040] 3) Mix 50 parts of silicone-modified acrylic resin, 15 parts of perfluoropolyether-modified siloxane, 1.5 parts of dispersant BYK-163, and 10 parts of solvent (propylene glycol methyl ether). Stir at 1000 rpm for 30 minutes to form a uniform and transparent premix.

[0041] 4) Add 10 parts of modified nitrogen-doped titanium dioxide nanotubes, 8 parts of nano-silica aerogel particles, and 15 parts of high-temperature resistant pigments and fillers to the premixed liquid in sequence. Disperse the mixture at 2500 rpm for 1.5 hours using a high-speed shearing machine. The fineness of the slurry is 20 μm (≤25 μm) as measured by a laser particle size analyzer.

[0042] 5) Add the remaining 10 parts solvent (propylene glycol methyl ether) and 1.5 parts leveling agent, stir for 30 minutes, test the viscosity with a Forecast 4 cup (25°C), adjust to 70s, filter through a 100-mesh filter to obtain the anti-fouling outer coating.

[0043] 6) The outer wall of the aluminum wok is degreased (alkaline degreasing agent, soaked at 50℃ for 10 minutes), derusted (oxalic acid solution, soaked at room temperature for 5 minutes), and dried. Electrostatic spraying is then applied at 60kV, a spraying distance of 20cm, and a wet film thickness of 30μm. It is cured in a 190℃ oven for 25 minutes and cooled to room temperature to form an anti-fouling outer coating (18μm thickness).

[0044] Table 1. Comparison of Embodiments and Prior Art As can be seen from Table 1, the performance of the external coating in Example 1 is significantly better than that of the prior art.

[0045] Example 2 1) Take the following materials: 40 parts of organosilicon modified acrylic resin, 20 parts of perfluoropolyether modified siloxane, 15 parts of nitrogen-doped titanium dioxide nanotubes, 5 parts of nano-silica aerogel particles, 10 parts of high-temperature resistant pigments and fillers, 2 parts of dispersant (BYK-163), 1 part of leveling agent (acrylate), and 20 parts of solvent (propylene glycol methyl ether).

[0046] 2) Add 15 parts of nitrogen-doped titanium dioxide nanotubes to an 8% (w / w) dilute nitric acid solution and ultrasonically clean for 30 minutes at 300W to remove the template agent; centrifuge and wash with deionized water (8000 rpm, 10 minutes) until the pH of the filtrate is 7.0, and vacuum dry at 80℃ for 4 hours; weigh 0.75 parts of KH-570 at 4% (w / w) of the mass of nitrogen-doped titanium dioxide nanotubes, dissolve in 10 mL of 70% (w / w) ethanol solution, and magnetically stir for 15 minutes until complete hydrolysis; add the pretreated nitrogen-doped titanium dioxide nanotubes to the above hydrolysis solution at a solid-liquid ratio of 1:10 (g:mL), and stir in a constant temperature water bath at 65℃ for 2.5 hours (400 rpm); centrifuge to separate the product, wash three times with anhydrous ethanol, and dry in an oven at 110℃ for 2 hours to obtain modified nitrogen-doped titanium dioxide nanotubes.

[0047] 3) Mix 40 parts of silicone-modified acrylic resin, 20 parts of perfluoropolyether-modified siloxane, 2 parts of dispersant BYK-163, and 10 parts of solvent (propylene glycol methyl ether). Stir at 1200 rpm for 30 minutes to form a uniform and transparent premix.

[0048] 4) Add 10 parts of modified nitrogen-doped titanium dioxide nanotubes, 8 parts of nano-silica aerogel particles, and 15 parts of high-temperature resistant pigments and fillers to the premixed liquid in sequence. Disperse the mixture at 3000 rpm for 2 hours using a high-speed shearing machine. The fineness of the slurry is 20 μm (≤25 μm) as measured by a laser particle size analyzer.

[0049] 5) Add the remaining 10 parts solvent (propylene glycol methyl ether) and 1 part leveling agent, stir for 30 minutes, test the viscosity with a Forecast 4 cup (25°C), adjust to 70s, filter through a 100-mesh filter to obtain the anti-fouling outer coating.

[0050] 6) The outer wall of the aluminum wok is degreased (alkaline degreasing agent, soaked at 50℃ for 10 minutes), derusted (oxalic acid solution, soaked at room temperature for 5 minutes), and dried. Electrostatic spraying is then applied at 60kV, a spraying distance of 20cm, and a wet film thickness of 30μm. It is cured in a 180℃ oven for 25 minutes and cooled to room temperature to form an anti-fouling outer coating (18μm thickness).

[0051] Table 2. Comparison of Embodiments and Prior Art As can be seen from Table 1, the performance of the external coating in Example 2 is significantly better than that of the prior art. At the same time, due to the increased amount of nitrogen-doped titanium dioxide nanotubes, the self-cleaning effect is significantly better than that in Example 1.

[0052] Example 3 1) Take the following materials: 60 parts of organosilicon modified acrylic resin, 10 parts of perfluoropolyether modified siloxane, 5 parts of nitrogen-doped titanium dioxide nanotubes, 10 parts of nano-silica aerogel particles, 20 parts of high-temperature resistant pigments and fillers, 1 part of dispersant (BYK-163), 2 parts of leveling agent (acrylate), and 20 parts of solvent (propylene glycol methyl ether).

[0053] 2) Five parts of nitrogen-doped titanium dioxide nanotubes were added to an 8% (w / w) dilute nitric acid solution and ultrasonically cleaned at 300W for 30 minutes to remove the template agent. The nanotubes were then centrifuged and washed with deionized water (8000 rpm, 10 minutes) until the pH of the filtrate was 7.0. The nanotubes were then vacuum dried at 80℃ for 4 hours. 0.25 parts of KH-570, which accounted for 4% of the mass of the nitrogen-doped titanium dioxide nanotubes, were weighed and dissolved in 10 mL of 90% (w / w) ethanol solution. The solution was magnetically stirred for 15 minutes until complete hydrolysis. The pretreated nitrogen-doped titanium dioxide nanotubes were added to the above hydrolysis solution at a solid-liquid ratio of 1:10 (g:mL). The solution was stirred in a constant temperature water bath at 65℃ for 2.5 hours (400 rpm). The product was centrifuged and washed three times with anhydrous ethanol. The product was then dried in an oven at 110℃ for 2 hours to obtain modified nitrogen-doped titanium dioxide nanotubes.

[0054] 3) Mix 60 parts of silicone-modified acrylic resin, 10 parts of perfluoropolyether-modified siloxane, 1 part of dispersant BYK-163, and 10 parts of solvent (propylene glycol methyl ether), and stir at 1500 rpm for 30 minutes to form a uniform and transparent premix.

[0055] 4) Add 5 parts of modified nitrogen-doped titanium dioxide nanotubes, 10 parts of nano-silica aerogel particles, and 20 parts of high-temperature resistant pigments and fillers to the premixed liquid in sequence. Disperse the mixture at 2000 rpm for 2 hours using a high-speed shearing machine. The fineness of the slurry is 20 μm (≤25 μm) as measured by a laser particle size analyzer.

[0056] 5) Add the remaining 10 parts solvent (propylene glycol methyl ether) and 2 parts leveling agent, stir for 30 minutes, test the viscosity with a Forecast 4 cup (25°C), adjust to 70s, filter through a 100-mesh filter to obtain the anti-fouling outer coating.

[0057] 6) The outer wall of the aluminum wok is degreased (alkaline degreasing agent, soaked at 50℃ for 10 minutes), derusted (oxalic acid solution, soaked at room temperature for 5 minutes), and dried. Electrostatic spraying is then applied at 60kV, a spraying distance of 20cm, and a wet film thickness of 30μm. It is cured in a 200℃ oven for 25 minutes and cooled to room temperature to form an anti-fouling outer coating (18μm thickness).

[0058] Table 3. Comparison of Embodiments and Prior Art As can be seen from Table 1, the performance of the external coating in Example 3 is significantly better than that of the prior art.

[0059] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A stain-resistant outer coating for kitchenware, characterized in that, The coating comprises the following components: silicone-modified acrylic resin, perfluoropolyether-modified siloxane, nitrogen-doped titanium dioxide nanotubes, nano-silica aerogel particles, and high-temperature resistant pigments and fillers. The coating possesses both passive anti-fouling and active self-cleaning functions. Passive anti-fouling is achieved through the low surface energy imparted by the perfluoropolyether-modified siloxane, while active self-cleaning is achieved through the visible light catalysis of nitrogen-doped titanium dioxide nanotubes.

2. The stain-resistant outer coating for kitchenware according to claim 1, characterized in that, The content of each raw material component by mass parts is as follows: 40-60 parts of organosilicon modified acrylic resin, 10-20 parts of perfluoropolyether modified siloxane, 5-15 parts of nitrogen-doped titanium dioxide nanotubes, 5-10 parts of nano-silica aerogel particles, and 10-20 parts of high-temperature resistant pigments and fillers.

3. The stain-resistant outer coating for kitchenware according to claim 2, characterized in that, The nitrogen-doped titanium dioxide nanotubes are surface-modified with a silane coupling agent; the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane.

4. The stain-resistant outer coating for kitchenware according to claim 2, characterized in that, It also includes a dispersant and a leveling agent, with the total mass fraction of the dispersant and leveling agent being 1-3 parts; the dispersant is BYK-163, and the leveling agent is an acrylate leveling agent.

5. The stain-resistant outer coating for kitchenware according to claim 2, characterized in that, The coating has a water contact angle >110°, an oil contact angle >80°, and a pencil hardness of 4-6H. It can be used for a long time in high-temperature environments above 250°C without discoloration or chalking.

6. The method for preparing an anti-fouling outer coating for kitchenware according to any one of claims 1-5, characterized in that: Includes the following steps: a) Surface modification treatment of nitrogen-doped titanium dioxide nanotubes to obtain modified nitrogen-doped titanium dioxide nanotubes; b) Mixing organosilicon-modified acrylic resin, perfluoropolyether-modified siloxane and a portion of solvent, and stirring at high speed to obtain a premixed solution. c) Add modified nitrogen-doped titanium dioxide nanotubes, nano-silica aerogel particles and high-temperature resistant pigments and fillers to the premix obtained in step b), and disperse at high speed to obtain a uniform slurry; d) Add the remaining solvent, dispersant and leveling agent to the slurry obtained in step c), adjust the viscosity of the coating to 60-80s (Ford-4 cup), and filter to obtain an anti-fouling outer coating.

7. The method for preparing the anti-fouling outer coating for kitchenware according to claim 6, characterized in that: In step c), high-speed dispersion is carried out using a high-speed shear mill or ball mill, with a dispersion speed of 2000-3000 rpm and a dispersion time of 1-2 hours. The fineness of the dispersed slurry is ≤25μm.

8. The method for preparing the anti-fouling outer coating for kitchenware according to claim 6, characterized in that: It also includes coating and curing steps: the coating obtained in step d) is electrostatically sprayed onto the outer surface of the pretreated kitchenware substrate and cured at 180-200℃ for 20-30 minutes to form an anti-fouling outer coating.

9. The method for preparing the anti-fouling outer coating for kitchenware according to claim 6, characterized in that: The specific process of surface modification in step a) is as follows: nitrogen-doped titanium dioxide nanotubes are mixed and reacted with silane coupling agent KH-570 in an ethanol solution, and then dried to obtain modified nitrogen-doped titanium dioxide nanotubes; the mass fraction of ethanol in the ethanol solution is 70%-90%.

10. The method for preparing the anti-fouling outer coating for kitchenware according to claim 6, characterized in that: In step b), the high-speed stirring speed is 1000-1500 rpm and the stirring time is 30 minutes; the solvent is propylene glycol methyl ether, and the solvent added in step b) accounts for 50% of the total solvent mass.

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