Non-stick ceramic coating with temperature indicating function as well as preparation method and use method of non-stick ceramic coating

Abstract

The invention discloses a non-stick ceramic coating with a temperature indicating function as well as a preparation method and a use method thereof. The transparent ceramic coating comprises a colored ceramic primer, a temperature-variable ceramic interlayer coating and a transparent ceramic finishing coat, wherein the primer comprises silica sol, 1% NaOH, methyltrimethoxysilane, a pigment, a filler, an alcohol organic solvent A, 25% formic acid, a leveling agent and the balance of deionized water; the temperature change coating contains silica sol, methyltrimethoxysilane, a temperature change pigment, a filler, fumed silica, 25% formic acid, a leveling agent and the balance of an alcohol organic solvent B; and the finish paint contains silica sol, methyltrimethoxysilane, an ether organic solvent, 25% formic acid, a flatting agent, a non-stick additive and the balance of deionized water. The temperature change pigment is added into the temperature change ceramic intermediate layer, and the color change temperature of the temperature change pigment is 150-200 DEG C, so that the characteristic of long-term temperature change reversibility of the coating is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic coatings and relates to a non-stick ceramic coating with a temperature indicating function and a preparation and use method thereof. Background Art

[0002] Cookware is a common kitchen appliance. Using the wrong oil temperature during cooking can not only produce a lot of smoke but also cause the cooking oil to oxidize and deteriorate, potentially posing a risk of cancer if consumed over a long period of time. To minimize health risks, it's crucial to carefully control the cooking oil temperature. However, visually measuring the oil temperature inside a cooker is difficult for most people. A method that can indicate the temperature inside the cooker would allow for better control of the cooking process. Consequently, temperature-indicating cookware has emerged on the market. These products incorporate temperature-sensitive pigments into the coating. When a certain temperature is reached, the pigment changes color, indicating the oil temperature.

[0003] Currently, temperature-indicating cookware on the market typically features a three-layer structure. The primer is a mixture of water-based fluororesin and water-based silicone resin. The middle layer is a color-changing layer, a thermochromic ink made by mixing temperature-changing pigments with water-based fluororesin and applied to the primer surface via screen printing or pad printing. The topcoat is a water-based fluororesin coating. The primer needs to be baked before the temperature-indicating layer is applied. This design relies on the recoatability of the silicone resin primer. However, ceramic coatings have high hardness, low surface tension, and poor recoatability. Using this process to manufacture temperature-indicating cookware can lead to poor adhesion between the three layers and coating detachment. Consequently, there are few temperature-indicating cookware made with ceramic coatings on the market. Cookware with ceramic coatings has become increasingly popular in recent years due to their safety, health, and high-temperature resistance. Therefore, a non-stick ceramic coating with temperature-indicating functionality is needed to meet consumer demand for ceramic-coated temperature-indicating cookware. Summary of the Invention

[0004] Ceramic coatings have high hardness and low surface tension, resulting in poor recoatability. If applied using the same process as commercially available temperature-indicating cookware, poor adhesion between the three layers of coating can occur, leading to the coating easily peeling off during use. The present invention aims to address this issue by providing a non-stick ceramic coating with a temperature-indicating function, as well as methods for its preparation and use. By incorporating a temperature-indicating pigment into the ceramic coating, a temperature-indicating non-stick ceramic coating is created. This coating exhibits long-term, reversible temperature-dependent color changes, with a color change temperature range of 150-200°C.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] <First Aspect>

[0007] The present invention provides a non-stick ceramic coating with a temperature display function, comprising a colored ceramic primer, a temperature-changing ceramic intermediate layer coating, and a transparent ceramic topcoat; wherein,

[0008] The colored ceramic primer is calculated as 100%, and the percentage of each component is as follows: silica sol 28-30%, 1% NaOH solution 4-5%, methyltrimethoxysilane 26-28%, pigment 12-15%, filler 8-10%, alcohol organic solvent A6-8%, 25% formic acid 0.6-0.8%, leveling agent 0.5-1% and the balance deionized water;

[0009] The temperature-changing ceramic intermediate layer coating, calculated as 100%, comprises the following components in percentages: 32-34% silica sol, 25-27% methyltrimethoxysilane, 8-10% temperature-changing pigment, 10-12% filler, 1.5-2% fumed silica, 25% formic acid, 0.6-0.8%, leveling agent, 0.5-1%, and the balance alcohol organic solvent B;

[0010] The transparent ceramic topcoat, calculated as 100%, has the following component percentages: silica sol 40-43%, methyltrimethoxysilane 38-40%, ether organic solvent 8-10%, 25% formic acid 0.6-0.8%, leveling agent 0.5-1%, non-stick additive 2-3%, and the balance deionized water.

[0011] As an embodiment of the present invention, the pigment is an inorganic pigment, and the color of the inorganic pigment is consistent with the color of the temperature-changing pigment after color change.

[0012] As an embodiment of the present invention, the reversible temperature change temperature of the temperature-changing pigment is 150-200°C.

[0013] As an embodiment of the present invention, the fillers in the colored ceramic primer and the temperature-variable ceramic intermediate layer coating are selected from one or more of calcined kaolin, heavy calcium carbonate, mica powder, silica powder, nano-alumina, and silicon carbide.

[0014] As an embodiment of the present invention, the alcohol organic solvent A is an alcohol organic solvent with a boiling point below 70°C; the alcohol organic solvent B is an alcohol solvent with a boiling point of 80°C-100°C; and the ether organic solvent is an ether organic solvent with a boiling point of 120°C-150°C.

[0015] As an embodiment of the present invention, the alcohol organic solvent A is methanol; or the alcohol organic solvent B is at least one of isopropanol and butanol; or the ether organic solvent is at least one of ethylene glycol ethyl ether, ethylene glycol methyl ether, and ethylene glycol butyl ether.

[0016] As an embodiment of the present invention, the non-stick auxiliary agent is selected from at least one of methyl silicone oil and hydroxy silicone oil.

[0017] <Second Aspect>

[0018] The present invention provides a method for preparing a non-stick ceramic coating with a temperature indicating function, the method comprising the following steps:

[0019] A. Preparation of colored ceramic primer:

[0020] A1. Prepare color paste: Mix silica sol, 1% NaOH, filler, pigment, and deionized water, grind to a fineness of less than 20 μm, and filter to obtain the color paste. The pH value of the color paste should be controlled between 9.5 and 10.0. If it is lower than 9.5, adjust it with 1% NaOH solution and set aside.

[0021] A2. Mix methyltrimethoxysilane, a leveling agent, and an alcohol organic solvent A, add 25% formic acid, mix evenly, then add the mixture to the color paste, and roll on a roller at 120-150 rpm for 4-6 hours to obtain a colored ceramic primer.

[0022] B. Preparation of temperature-changing ceramic intermediate layer coating:

[0023] B1. Preparation of temperature-changing color paste: Mix silica sol, temperature-changing pigment, and fumed silica, grind to a fineness of less than 20 μm, filter to obtain the temperature-changing color paste, and set aside;

[0024] B2. Mix methyltrimethoxysilane, leveling agent, and alcohol organic solvent B evenly, then add 25% formic acid and mix evenly, then add to the temperature-changing color paste, and roll on a roller at 120-150 rpm for 4-6 hours to obtain a temperature-changing ceramic intermediate layer coating;

[0025] C. Preparation of transparent ceramic topcoat:

[0026] C1. Mix silica sol and deionized water, roll on a roller stand at 120-150 r / min for 10-20 minutes, and set aside;

[0027] C2. Evenly mix methyltrimethoxysilane, 25% formic acid, a leveling agent, a non-stick additive, and an ether organic solvent, and immediately add the mixture to the solution obtained in C1. Roll and mature on a roller at 120-180 rpm for 6-8 hours to obtain a transparent ceramic topcoat.

[0028] <Third Aspect>

[0029] The present invention provides a non-stick ceramic coating structure prepared from the aforementioned non-stick ceramic coating with a temperature indication function, comprising a colored ceramic primer layer, a temperature-variable ceramic intermediate layer, and a transparent ceramic topcoat layer; the total thickness of the three layers is 32-45 μm, of which the colored ceramic primer layer is 20-25 μm, the temperature-variable ceramic intermediate layer is 6-10 μm, and the transparent ceramic topcoat layer is 6-10 μm.

[0030] <Fourth Aspect>

[0031] The present invention provides a method for preparing a non-stick ceramic coating structure with a temperature indicating function, the method comprising the following steps:

[0032] D1. Pre-treatment of substrate to make its roughness Ra=2.5-4.0μm;

[0033] D2. Preheat the substrate to 45-60℃, spray the colored ceramic primer, and then bake at 50-70℃ for 2-3 minutes to reach the surface dry state;

[0034] D3. Use silk screen printing or pad printing to form a pattern on the primer surface using the temperature-changing ceramic intermediate layer coating.

[0035] D4. Spray transparent ceramic topcoat, first bake at a low temperature of 60-80℃ for 5-6 minutes, then bake at a medium temperature of 85-110℃ for 5-6 minutes, and then bake at a high temperature of 180-260℃ for 10-15 minutes to complete the curing.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) By adding solvents with different boiling points into the primer, temperature-variable intermediate layer and topcoat, and adopting three-stage curing conditions of low temperature, medium temperature and high temperature to control the volatilization rate of the solvent, the siphon effect and atmospheric pressure are used to make the three layers blend together well, thereby increasing the adhesion between the layers; the existing construction technology of temperature-indicating cookware is used to produce temperature-indicating ceramic non-stick cookware with excellent adhesion.

[0038] (2) By adding a thermochromic pigment into the thermochromic ceramic intermediate layer, where the color change temperature of the thermochromic pigment is between 150-200°C, the long-term temperature-change reversible property of the coating is achieved. That is, at room temperature, the color of the thermochromic layer is significantly different from the base color, and the pattern or text printed with the thermochromic material is clearly visible. After heating, as the temperature of the cooker gradually increases, the color of the thermochromic material will also change. When the temperature in the pot reaches about 180-200°C, which is the optimal temperature for cooking, the color of the thermochromic material becomes exactly the same as the base color, and the letters or patterns will completely disappear, prompting the user to start cooking, which provides great convenience for cooking.

[0039] (3) The present invention indicates the cooking temperature through intuitive visual changes, avoiding the tedious use of tools such as thermometers, while also reducing cooking problems caused by improper temperature control. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0041] Figure 1 This is an example diagram of the application of the non-stick ceramic coating with temperature indication function of the present invention. DETAILED DESCRIPTION

[0042] The present invention is further illustrated by the following examples, but any example or combination thereof should not be construed as limiting the scope or implementation of the present invention. Without departing from the spirit and scope of the present invention, those skilled in the art may make any modifications or changes to the technical solution of the present invention, and such modifications and changes are also included in the scope of the present invention.

[0043] In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer's recommendations. All reagents or instruments that do not specify the manufacturer are conventional products that can be purchased commercially. In order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented equally without certain specific details. In other embodiments, methods, means, equipment and steps well known to those skilled in the art are not described in detail to highlight the main purpose of the present invention.

[0044] The non-stick ceramic coating with temperature indication function is divided into a colored ceramic primer layer, a temperature-changing ceramic middle layer and a transparent ceramic topcoat layer.

[0045] (1) The colored ceramic primer layer is calculated as 100%, and the percentages of the various components are as follows:

[0046] Silica sol 28-30%, 1% NaOH solution 4-5%, methyltrimethoxysilane 26-28%, pigment 12-15%, filler 8-10%, alcohol organic solvent 6-8%, 25% formic acid 0.6-0.8%, leveling agent 0.5-1% and the balance deionized water.

[0047] Silica sol: the main film-forming substance of ceramic coatings, common commercial products, such as Akzo Nobel's Bindzil2034DI, Nissan Chemical's ST-O-40, Grace HS-40, etc.

[0048] 1% NaOH solution: mass percentage, color paste pH value adjustment, after grinding the color paste pH value is between 9.5-10.0.

[0049] Methyltrimethoxysilane: auxiliary film-forming substance, common commercial product.

[0050] Pigments: As pigments for the inner coating of cookware and food contact containers, inorganic pigments are usually used. They are non-toxic, do not contain heavy metals, and have good temperature resistance. Select the pigment according to the color that the temperature-changing pigment will show after the color changes, so that the color of the temperature-changing pigment is exactly the same as the primer color after the color changes. Under normal temperature conditions, the color of the temperature-changing layer is obviously different from the base color, and the pattern or text printed with the temperature-changing material is clearly visible. After heating, as the temperature of the cookware gradually increases, the color of the temperature-changing material will also change. When the temperature in the pot reaches about 180-200℃, which is the best temperature for cooking, the color of the temperature-changing material becomes exactly the same as the base color, and the letters or patterns will completely disappear (such as Figure 1 As shown), the user is prompted to put in the ingredients for cooking, which provides great convenience for cooking.

[0051] Filler: one or more of calcined kaolin, heavy calcium, mica powder, silica powder, nano alumina, and silicon carbide.

[0052] Alcohol organic solvents: Common commercially available products. Primer solvents should be alcohols with a boiling point below 70°C, such as methanol. Methyltrimethoxysilane hydrolyzes to produce methanol, which is compatible with the added solvent and does not affect the compatibility and stability of the system. Low solvent content results in poor intercoat adhesion, while high solvent content can lead to sagging during spraying.

[0053] 25% formic acid solution: A catalyst for the sol-gel reaction of ceramic coatings. Silane hydrolyzes under acidic conditions, undergoing a polycondensation reaction with silica sol to form the ceramic coating. Due to the significant differences in acidity between different acids, other acids, such as acetic acid, citric acid, hydrochloric acid, benzoic acid, and oxalic acid, cannot be used in this invention's formulation. Firstly, at these concentrations and dosages, substituting these acids can significantly alter the coating's pH, potentially causing gelation and rendering it unusable. Secondly, the performance of ceramic coatings is closely linked to their pH; an inappropriate pH value can severely impact the final coating's performance.

[0054] Leveling agent: It helps the paint form a flat, smooth, and uniform coating during the drying process. Water-based paint leveling agents such as BYK333.

[0055] (2) Thermostatic ceramic intermediate layer, based on 100%, the percentages of the components are as follows: silica sol 32-34%, methyltrimethoxysilane 25-27%, thermostatic pigment 8-10%, filler 10-12%, fumed silica 1.5-2%, 25% formic acid 0.6-0.8%, leveling agent 0.5-1%, and the balance alcohol organic solvent. Among them:

[0056] Thermochromic pigments: Common commercially available products have a reversible temperature range of 150-200°C. This means the color begins to change when heated to around 150°C, completes at 200°C, and returns to its original color upon cooling. Examples include F-R200 from Jinhua Lijin Technology Co., Ltd. and TTR-150 from Shenzhen Qiansebian New Material Technology Co., Ltd.

[0057] Fumed silica: Inorganic thickener that increases the viscosity of the temperature-dependent intermediate layer, facilitating the creation of clear patterns during pad printing or silk-screen printing.

[0058] Organic solvents: Common commercially available products. For the temperature-sensitive interlayer, alcohols with a boiling point of 80°C-100°C, such as isopropyl alcohol and butanol, are suitable. Methyltrimethoxysilane hydrolyzes to produce methanol, which has a similar structure to the added solvent and does not affect the compatibility and stability of the system. Low solvent content results in poor interlayer adhesion, while high solvent content can lead to sagging during spraying.

[0059] (3) The transparent ceramic topcoat layer, calculated as 100%, comprises the following components in percentages: silica sol 40-43%, methyltrimethoxysilane 38-40%, ether organic solvent 8-10%, 25% formic acid 0.6-0.8%, leveling agent 0.5-1%, non-stick additive 2-3%, and the balance deionized water.

[0060] Ether organic solvents: Common commercially available products. Ethers with a boiling point of 120°C-150°C are used as solvents for the transparent topcoat layer. These solvents, such as ethylene glycol ethyl ether, ethylene glycol methyl ether, and ethylene glycol butyl ether, evaporate very slowly or even not at all during low-temperature baking. However, they evaporate rapidly at baking temperatures above 180°C, allowing the coating surface to dry quickly and solidify. Low solvent content results in poor interlayer adhesion, while high solvent content can lead to sagging during spraying.

[0061] Non-stick additives: provide non-stick properties for the topcoat. Commonly used non-stick additives include methyl silicone oil, hydroxy silicone oil, etc.

[0062] The preparation steps of the non-stick ceramic coating with temperature indication function include the following steps:

[0063] 1. Preparation of colored ceramic primer:

[0064] (1) Preparation of color paste: Silica sol, 1% NaOH, filler, pigment, and deionized water were mixed and ground on a grinder to a fineness of less than 20 μm. The color paste was filtered through a 300-mesh filter cloth to obtain the color paste. The pH value of the color paste was measured to be between 9.5 and 10.0. If it was lower than 9.5, it was adjusted with 1% NaOH solution and set aside.

[0065] (2) Methyltrimethoxysilane, a leveling agent, and an alcohol organic solvent are mixed evenly, and then 25% formic acid is added and mixed evenly, and then quickly added to the color paste of step (1), and rolled on a roller at 120-150 r / min for 4-6 hours to obtain a colored ceramic primer.

[0066] The above reaction process is as follows: first, methyltrimethoxysilane is hydrolyzed in an acidic environment to form silanol (Si-OH), and then silanol reacts with -OH on the surface of silica sol through condensation to form a ceramic primer with a Si-O-Si cross-linked structure.

[0067] 2. Preparation of temperature-changing ceramic coatings:

[0068] (1) Preparation of temperature-changing color paste: Silica sol, temperature-changing pigment and fumed silica were mixed, ground on a grinder to a fineness of less than 20 μm, and filtered through a 300-mesh filter cloth to obtain a color paste for later use.

[0069] (2) Methyltrimethoxysilane, a leveling agent, and an alcohol organic solvent are mixed evenly, and then 25% formic acid is added and mixed evenly, and then quickly added to the color paste of step (1), and rolled on a roller at 120-150 r / min for 4-6 hours to obtain a temperature-sensitive ceramic coating.

[0070] 3. Preparation of transparent ceramic topcoat:

[0071] (1) Mix silica sol and deionized water, roll on a roller rack at 120-150 r / min for 10-20 minutes, and set aside;

[0072] (2) Methyltrimethoxysilane, 25% formic acid, a leveling agent, a non-stick additive, and an ether organic solvent are mixed evenly, and immediately added to the solution obtained in step (1). After rolling and aging on a roller at 120-180 r / min for 6-8 hours, a transparent ceramic topcoat is obtained.

[0073] The construction method of the above-mentioned non-stick ceramic coating with temperature indication function is as follows:

[0074] 1. Substrate Pretreatment: Spray 60-100 mesh white corundum or brown corundum onto the substrate surface to a roughness of Ra = 2.5-4.0 μm. This has two purposes: (1) to remove dirt and oil stains from the substrate surface; (2) to create a certain roughness to increase the contact area between the coating and the substrate, ensuring good adhesion between the coating and the substrate.

[0075] 2. Preheat the substrate to 45-60℃, spray the colored ceramic primer, and then bake it at 50-70℃ for 2-3 minutes to reach the surface dry state, that is, the coating surface is not sticky to the touch, and then use the temperature-changing ceramic coating to form a certain pattern on the primer surface by screen printing or pad printing.

[0076] 3. Then spray the transparent ceramic topcoat, first bake at a low temperature of 60-80℃ for 5-6 minutes, then bake at a medium temperature of 80-110℃ for 5-6 minutes, and then bake at a high temperature of 180-260℃ for 10-15 minutes to complete the curing.

[0077] The total thickness of the three layers is 32-45μm, including a 20-25μm primer layer, a 6-10μm intermediate temperature-sensitive layer, and a 6-10μm clear topcoat layer. The intermediate temperature-sensitive layer should not exceed 10μm. If it is too thick, the thickness difference between the patterned and unpatterned areas of the coating will be too large, causing the patterned areas to wear more severely during use, resulting in a rapid decrease in the non-stick properties of these areas, affecting the user experience.

[0078] The non-stick coating produced using the above method comprises, from bottom to top, a colored ceramic primer, a temperature-dependent ceramic coating, and a transparent ceramic topcoat. These three layers use organic solvents with different boiling points. When baked at a low temperature of 60-80°C, the low-boiling-point organic solvent in the primer layer evaporates in large quantities, creating numerous vacuum voids in the volume it occupies. At this time, the temperature-dependent ceramic intermediate layer, which maintains good fluidity, penetrates into the colored ceramic primer layer under the siphon effect and atmospheric pressure. As baking progresses, the fluidity of the primer layer decreases, allowing the primer and intermediate layers to blend well together. When the baking temperature rises to 80-110°C, the medium-boiling-point organic solvent in the temperature-dependent intermediate layer begins to evaporate in large quantities, also creating numerous vacuum voids in the volume it occupies. At this time, the transparent ceramic topcoat, which maintains good fluidity, penetrates into the temperature-dependent ceramic intermediate layer under the siphon effect and atmospheric pressure. As baking progresses, the fluidity of the intermediate layer decreases, allowing the intermediate layer and topcoat layer to blend well together. Finally, high-temperature baking and curing accelerate the volatilization of the high-boiling-point organic solvent in the topcoat, thereby completing the curing process of the entire coating.

[0079] The curing temperature is determined by the boiling points of the organic solvents in the three layers. Low-temperature baking causes a large amount of organic solvent in the bottom layer to evaporate, while the solvents in the middle and topcoat layers are essentially non-volatile or evaporate very slowly. Medium-temperature baking requires a large amount of organic solvent in the middle layer to evaporate, while the solvent in the topcoat layer evaporates very slowly. During high-temperature baking, the high-boiling-point solvent in the topcoat layer evaporates in large quantities. By controlling the curing temperature, the evaporation rate of the organic solvents in the three layers is controlled, thus forming a vacuum gap. This allows the upper layer of paint to enter the lower layer under the siphon effect and atmospheric pressure, and achieve a strong bond between the layers through hydrolysis and polymerization. Microstructurally, the upper layer of paint is embedded in the lower layer of paint. This structure ensures the strength and thermal conductivity of the overall ceramic coating, making the coating strong and able to accurately reflect temperature changes.

[0080] Example 1

[0081] This embodiment provides a non-stick ceramic coating with a temperature-indicating function, comprising a colored ceramic primer, a temperature-variable ceramic intermediate coating, and a transparent ceramic topcoat. The specific composition is shown in Table 1. The preparation methods of each coating layer are as follows:

[0082] 1. Preparation of colored ceramic primer:

[0083] (1) Preparation of color paste: Silica sol, 1% NaOH, filler, pigment, and deionized water were mixed and ground on a grinder to a fineness of less than 20 μm. The color paste was filtered through a 300-mesh filter cloth to obtain the color paste. The pH value of the color paste was measured to be between 9.5 and 10.0. If it was lower than 9.5, it was adjusted with 1% NaOH solution and set aside.

[0084] (2) Methyltrimethoxysilane, a leveling agent, and an alcohol organic solvent are mixed evenly, and then 25% formic acid is added and mixed evenly, and then quickly added to the color paste of step (1), and rolled and matured on a roller at 150 r / min for 5 hours to obtain a colored ceramic primer.

[0085] 2. Preparation of temperature-changing ceramic intermediate layer coating:

[0086] (1) Preparation of temperature-changing color paste: Silica sol, temperature-changing pigment, and fumed silica were mixed, ground on a grinder to a fineness of less than 20 μm, and filtered through a 300-mesh filter cloth to obtain a color paste for later use;

[0087] (2) Methyltrimethoxysilane, a leveling agent, and an alcohol organic solvent were mixed evenly, and then 25% formic acid was added and mixed evenly. Then, the mixture was quickly added to the color paste of step (1), and the mixture was rolled and matured on a roller at 150 r / min for 5 hours to obtain a temperature-sensitive ceramic coating.

[0088] 3. Preparation of transparent ceramic topcoat:

[0089] (1) Mix silica sol and deionized water, roll on a roller stand at 150 r / min for 15 minutes, and set aside;

[0090] (2) Methyltrimethoxysilane, 25% formic acid, a leveling agent, a non-stick additive, and an ether organic solvent were mixed evenly, and immediately added to the solution obtained in step (1). After rolling and aging on a roller at 180 r / min for 7 hours, a transparent ceramic topcoat was obtained.

[0091] The above coating is used to prepare a non-stick ceramic coating with a temperature indicating function. The specific steps are as follows:

[0092] 1. Substrate pretreatment: 80-mesh white corundum sand is sprayed on the surface of the substrate (either aluminum alloy or stainless steel, aluminum alloy is selected in this embodiment; the same is true for the other embodiments and comparative examples), and the roughness Ra is controlled at about 3.0 μm.

[0093] 2. Preheat the substrate to 50℃, spray the colored ceramic primer, and then bake it at 60℃ for 3 minutes to reach the surface dry state. Then use the temperature-changing ceramic coating to form certain text on the primer surface by silk screen printing (such as Figure 1 ).

[0094] 3. Then, apply a transparent ceramic topcoat, first baking at 70°C for 5 minutes, then baking at 100°C for 5 minutes, and finally baking at 220°C for 12 minutes to complete the curing process. Each layer of paint is applied to a total thickness of approximately 40μm, including a primer layer of approximately 20μm, a temperature-dependent intermediate thickness of approximately 10μm, and a clear topcoat layer of approximately 10μm.

[0095] Examples 2 and 3

[0096] Examples 2 and 3 each provide a non-stick ceramic coating with a temperature indication function, comprising a colored ceramic primer, a temperature-variable ceramic intermediate layer coating, and a transparent ceramic topcoat; the specific composition is shown in Table 1; the preparation of each coating layer and the coating structure is basically the same as in Example 1.

[0097] Comparative Examples 1-3

[0098] Comparative Examples 1-3 each provide a non-stick ceramic coating with a temperature indication function, comprising a colored ceramic primer, a temperature-variable ceramic intermediate layer coating, and a transparent ceramic topcoat; the specific composition is shown in Table 1; the preparation of each coating layer and the coating structure is basically the same as in Example 1.

[0099] Comparative Example 4

[0100] The non-stick ceramic coating of Comparative Example 4 comprises a colored ceramic primer, a temperature-dependent ceramic intermediate layer, and a transparent ceramic topcoat. The specific composition is shown in Table 1. The preparation of each coating layer is essentially the same as in Example 1. The coating preparation differs from Example 1 only in that, in step 3, the coating is cured by baking at 70°C for 22 minutes.

[0101] Comparative Example 5

[0102] The non-stick ceramic coating of Comparative Example 5 comprises a colored ceramic primer, a temperature-sensitive ceramic intermediate layer, and a transparent ceramic topcoat; the specific composition is shown in Table 1. The preparation of each coating layer is essentially the same as in Example 1. The coating preparation differs from Example 1 only in that, in step 3, the coating is baked at 100°C for 22 minutes to complete the curing.

[0103] Comparative Example 6

[0104] The non-stick ceramic coating of Comparative Example 4 comprises a colored ceramic primer, a temperature-dependent ceramic intermediate layer, and a transparent ceramic topcoat. The specific composition is shown in Table 1. The preparation of each coating layer is essentially the same as in Example 1. The coating preparation differs from Example 1 only in that, in step 3, the coating is cured by baking at 220°C for 22 minutes.

[0105] Table 1 Coating composition and dosage of Examples and Comparative Examples (wt.%)

[0106]

[0107]

[0108]

[0109] Note: Inorganic pigments are selected according to the color of the temperature-dependent pigments, for example: Figure 1 And iron oxide red is selected in Table 1. The compositions of Comparative Examples 4-6 are the same as those of Example 1, except that the curing methods are different.

[0110] The coatings prepared in the above examples and comparative examples were subjected to main performance tests:

[0111] (1) Test item: Pencil hardness; Test method: Use a Mitsubishi pencil to scratch 10 mm in parallel at a 45° angle with a force of 10 N, and repeat the test 5 times;

[0112] (2) Test item: Adhesion; Test method: 100-grid method, use a single-sided blade to cut parallel and vertical cuts on the coating film, the depth is required to penetrate the entire thickness of the paint film, the cut spacing is 2.0mm, use 3M-898 tape to repeatedly stick and peel 5 times, and check that each scratch has no jagged cracks;

[0113] (3) Test item: gloss; test method: gloss meter, 60°, measure three times at different locations on the same plane, and take the average value;

[0114] (4) Test item: Salt water resistance; Test method: GB / T 9274-1988, three cycles of testing;

[0115] (5) Test item: Resistance to cold and hot shock; Test method: 300℃×2min, then put into ice-water mixed solution, one cycle;

[0116] (6) Test item: High-temperature non-stick durability; Test method: First, place the pot on a household gas stove, heat it at 300-320°C for 30 minutes, cool it naturally, and then fry eggs without oil at 180-200°C for 90 seconds. Fry 10 eggs in one cycle.

[0117] (7) Test item: reversible stability of thermochromic change; test method: turn on the high heat of a household gas stove, raise the temperature of the pot to 220°C, and observe the color change of the thermochromic layer. If the thermochromic layer changes color normally with the temperature increase, rinse with tap water and cool to room temperature. Count as one cycle.

[0118] (8) Test item: Abrasion resistance; Test method: 3.0 kg pressure, 5 cm × 5 cm scouring pad (3M 7447C), soaked in 5 g / L detergent solution, rubbed back and forth on the coating, one round trip counted as one, and the scouring pad was replaced every 250 times until three scratches appeared on the coating.

[0119] (9) Test item: Abrasion resistance and non-stick properties; Test method: (1) Rub the coating back and forth with a 5 cm x 5 cm scouring pad (3M7447C) at a pressure of 1.5 kg. Each back and forth counts as one rub. Continue rubbing for 500 times. (2) Fry an egg in oil-free water at 180-210°C for 90 seconds. (3) Repeat the above steps until the egg is at level 3 or below (the egg adheres to the coating by more than 20%).

[0120] The main performance tests of the coatings in each embodiment and comparative example are shown in Tables 2 and 3:

[0121] Table 2

[0122]

[0123] Table 3

[0124]

[0125]

[0126] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A non-stick ceramic coating with a temperature indication function, characterized in that: Contains colored ceramic primer, temperature-changing ceramic intermediate coating and transparent ceramic topcoat; among which, The colored ceramic primer is calculated as 100%, and the percentage of each component is as follows: silica sol 28-30%, 1% NaOH solution 4-5%, methyltrimethoxysilane 26-28%, pigment 12-15%, filler 8-10%, alcohol organic solvent A6-8%, 25% formic acid 0.6-0.8%, leveling agent 0.5-1% and the balance deionized water; The temperature-changing ceramic intermediate layer coating, calculated as 100%, comprises the following components in percentages: 32-34% silica sol, 25-27% methyltrimethoxysilane, 8-10% temperature-changing pigment, 10-12% filler, 1.5-2% fumed silica, 25% formic acid, 0.6-0.8%, leveling agent, 0.5-1%, and the balance alcohol organic solvent B; The transparent ceramic topcoat, calculated as 100%, has the following component percentages: silica sol 40-43%, methyltrimethoxysilane 38-40%, ether organic solvent 8-10%, 25% formic acid 0.6-0.8%, leveling agent 0.5-1%, non-stick additive 2-3%, and the balance deionized water.

2. The non-stick ceramic coating with temperature indication function according to claim 1, characterized in that: The pigment is an inorganic pigment, and the color of the inorganic pigment is consistent with the color of the temperature-changing pigment after color change.

3. The non-stick ceramic coating with temperature indication function according to claim 1, characterized in that: The reversible temperature change temperature of the temperature-changing pigment is 150-200°C.

4. The non-stick ceramic coating with temperature indication function according to claim 1, characterized in that: The fillers in the colored ceramic primer and the temperature-variable ceramic intermediate layer coating are selected from one or more of calcined kaolin, heavy calcium carbonate, mica powder, silica powder, nano-alumina, and silicon carbide.

5. The non-stick ceramic coating with temperature indication function according to claim 1, characterized in that: The alcohol organic solvent A is an alcohol organic solvent with a boiling point below 70°C; the alcohol organic solvent B is an alcohol solvent with a boiling point of 80°C-100°C; and the ether organic solvent is an ether organic solvent with a boiling point of 120°C-150°C.

6. The non-stick ceramic coating with temperature indicating function according to claim 1 or 5, characterized in that: The alcohol organic solvent A is methanol; or the alcohol organic solvent B is at least one of isopropanol and butanol; or the ether organic solvent is at least one of ethylene glycol ethyl ether, ethylene glycol methyl ether, and ethylene glycol butyl ether.

7. The non-stick ceramic coating with temperature indication function according to claim 1, characterized in that: The non-stick auxiliary agent is selected from at least one of methyl silicone oil and hydroxy silicone oil.

8. A method for preparing a non-stick ceramic coating with a temperature indicating function as claimed in claim 1, characterized in that: The method comprises the following steps: A. Preparation of colored ceramic primer: A1. Prepare color paste: Mix silica sol, 1% NaOH, filler, pigment, and deionized water, grind to a fineness of less than 20 μm, and filter to obtain the color paste. The pH value of the color paste should be controlled between 9.5 and 10.

0. If it is lower than 9.5, adjust it with 1% NaOH solution and set aside. A2. Mix methyltrimethoxysilane, a leveling agent, and an alcohol organic solvent A, add 25% formic acid, mix evenly, then add the mixture to the color paste, and roll on a roller at 120-150 rpm for 4-6 hours to obtain a colored ceramic primer. B. Preparation of temperature-changing ceramic intermediate layer coating: B1. Preparation of temperature-changing color paste: Mix silica sol, temperature-changing pigment, and fumed silica, grind to a fineness of less than 20 μm, filter to obtain the temperature-changing color paste, and set aside; B2. Mix methyltrimethoxysilane, leveling agent, and alcohol organic solvent B evenly, then add 25% formic acid and mix evenly, then add to the temperature-changing color paste, and roll on a roller at 120-150 rpm for 4-6 hours to obtain a temperature-changing ceramic intermediate layer coating; C. Preparation of transparent ceramic topcoat: C1. Mix silica sol and deionized water, roll on a roller stand at 120-150 r / min for 10-20 minutes, and set aside; C2. Evenly mix methyltrimethoxysilane, 25% formic acid, a leveling agent, a non-stick additive, and an ether organic solvent, and immediately add the mixture to the solution obtained in C1. Roll and mature on a roller at 120-180 rpm for 6-8 hours to obtain a transparent ceramic topcoat.

9. A non-stick ceramic coating structure prepared from the non-stick ceramic coating with a temperature indication function according to claim 1, comprising a colored ceramic primer layer, a temperature-variable ceramic intermediate layer, and a transparent ceramic topcoat layer; the total thickness of the three layers is 32-45 μm, of which the colored ceramic primer layer is 20-25 μm, the temperature-variable ceramic intermediate layer is 6-10 μm, and the transparent ceramic topcoat layer is 6-10 μm.

10. A method for preparing the non-stick ceramic coating structure according to claim 9, characterized in that: The method comprises the following steps: D1. Pre-treatment of substrate to make its roughness Ra=2.5-4.0μm; D2. Preheat the substrate to 45-60℃, spray the colored ceramic primer, and then bake at 50-70℃ for 2-3 minutes to reach the surface dry state; D3. Use silk screen printing or pad printing to form a pattern on the primer surface using the temperature-changing ceramic intermediate layer coating. D4. Spray transparent ceramic topcoat, first bake at a low temperature of 60-80℃ for 5-6 minutes, then bake at a medium temperature of 85-110℃ for 5-6 minutes, and then bake at a high temperature of 180-260℃ for 10-15 minutes to complete the curing.

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