Ceramic coating capable of blocking migration of heavy metal ions as well as preparation method and application of ceramic coating

Abstract

The invention discloses a ceramic coating capable of blocking heavy metal ion migration and a preparation method and application thereof. The ceramic coating comprises a component A, a component B, a component C and a component D, and the weight ratio of the component A to the component B to the component C to the component D is 100: (1-10): (40-80): (7-15); the component A comprises the following raw materials in parts by weight: 30-90 parts of silica sol; 10 to 29 parts of filler; 0-25 parts of a temperature-resistant pigment; 0-3 parts of a thickening agent; 0-3 parts of a dispersant; 0 to 20 parts of deionized water; the component B is graphene oxide; the component C is prepared from the following raw materials in parts by weight: 90 to 99 parts of siloxane; 1-10 parts of silicone oil; 1-6 parts of a catalyst; the component D comprises the following raw materials in parts by weight: 50-90 parts of a solvent; 2-20 parts of a leveling agent; and 0-9 parts of a defoaming agent. The ceramic coating provided by the invention is good in compactness, can effectively prevent migration of heavy metal ions, and meanwhile, improves the saline-resistant non-stick property and detergent-resistant non-stick property of a ceramic coating.

Description

Technical Field

[0001] This application relates to the field of ceramic coating technology, and in particular to a ceramic coating that blocks the migration of heavy metal ions, its preparation method, and its application. Background Technology

[0002] Ceramic coatings, as a commonly used non-stick coating for cookware, are a type of food contact material. Both China and the European Union have set clear limits on the migration of various heavy metals in food contact materials. Limiting the migration of heavy metals essentially means blocking the migration of heavy metal ions, which in turn places high demands on the density of the coating.

[0003] Currently, there are three common techniques for improving the density of ceramic coatings. The first is to increase the degree of crosslinking, such as increasing the proportion of crosslinking components or selecting silanes with more crosslinking groups. This has some effect on improving the density of the coating, but it still cannot form a very dense coating and cannot effectively block the migration of heavy metal ions. Furthermore, if the degree of crosslinking is too high, the coating is prone to cracking. The second method is to select some high-density, compact fillers and combine them according to a normal distribution of different particle sizes and masses to form a ceramic coating with a certain degree of density. However, the density is still insufficient, and the amount of heavy metal migration still exceeds the standard. The third method is to add polymeric resin materials, such as polyurethane and epoxy resin, to the ceramic coating. This method can prepare a coating that blocks the migration of heavy metal ions, but it greatly affects the non-stick properties of the ceramic coating, significantly reducing its non-stickiness.

[0004] Therefore, it is necessary to improve the density of ceramic coatings without reducing their various properties. Summary of the Invention

[0005] The ceramic coating provided in this application has good density, which can effectively prevent the migration of heavy metal ions, and at the same time improve the salt water resistance and detergent resistance of the ceramic coating prepared by using the ceramic coating.

[0006] A ceramic coating for blocking the migration of heavy metal ions, the ceramic coating comprising component A, component B, component C, and component D, wherein the weight ratio of component A, component B, component C, and component D is 100:1 to 10:40 to 80:7 to 15.

[0007] The raw material composition of component A by weight is as follows:

[0008]

[0009] Component B is graphene oxide;

[0010] The raw material composition of component C is as follows by weight:

[0011]

[0012] The raw material composition of component D is as follows by weight:

[0013]

[0014] Component A is a mixture of various substances, wherein the filler is at least one of silicon carbide, ceramic powder, barium sulfate, mica, silicon nitride, zirconium oxide, alumina, glass flakes, talc, silica, barite, kaolin, silica fume, and whisker silicon; the heat-resistant pigment is at least one of titanium dioxide, copper chromium black, iron chromium black, carbon black, manganese iron black, titanium nickel yellow, iron oxide yellow, titanium chromium brown, phthalocyanine blue, phthalocyanine green, titanium yellow, bismuth yellow, iron oxide red, cadmium red, cobalt blue, cobalt green, and pearlescent pigment; the thickener is an aqueous thickener; and the dispersant is an aqueous dispersant.

[0015] More preferably, the filler is at least one selected from silicon carbide, ceramic powder, barium sulfate, mica, and silicon micro powder.

[0016] The C component is a mixture of multiple substances, wherein the silicone oil is at least one of dimethyl silicone oil, hydroxyl silicone oil, amino silicone oil, hydrogen-containing silicone oil, phenolic hydroxyl silicone oil, alcoholic hydroxyl silicone oil, and mercapto silicone oil.

[0017] Component C is a mixture of multiple substances, wherein the solvent is at least one of isopropanol, ethanol, propylene glycol methyl ether, isohexyl glycol, ethylene glycol butyl ether, and dipropylene glycol butyl ether; the defoamer is a water-based defoamer, and the leveling agent is a water-based leveling agent.

[0018] This application describes a ceramic coating that blocks the migration of heavy metal ions by adding graphene oxide to the ceramic coating. The reaction mechanism is as follows: First, siloxanes hydrolyze to generate silanols, such as... Figure 1 As shown; then, because the silica particles in the silica sol have many hydroxyl groups, graphene oxide will undergo a ternary polymerization reaction with silanol and silica sol, as shown. Figure 2 As shown, after high-temperature baking, condensation and dehydration occur, resulting in a very dense ceramic coating that can block the migration of heavy metal ions.

[0019] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0020] Further preferably, the raw material composition of component A is as follows by weight:

[0021]

[0022]

[0023] More preferably, the raw material composition of component C is as follows by weight:

[0024]

[0025] Further preferably, the raw material composition of component D is as follows by weight:

[0026]

[0027] Further preferably, the raw material composition of component D is as follows by weight:

[0028]

[0029] Preferably, the weight ratio of component A to component B is 100:2 to 5. More preferably, the weight ratio of component A to component B is 100:3 to 4. Under these preferred weight ratio conditions, the ceramic coating can block the migration of heavy metal ions and improve its resistance to salt water and detergent stickiness.

[0030] Preferably, the weight ratio of component A to component C is 100:45 to 65.

[0031] Preferably, the weight ratio of component A to component D is 100:8 to 12.

[0032] Preferably, the silica sol is an alkaline silica sol, with a solid mass fraction of 30% to 45% and a particle size of 15 to 60 nm.

[0033] Preferably, the graphene oxide is a single-layer graphene oxide with a particle size of 3-15 μm and a purity of ≥99%.

[0034] Preferably, the siloxane is at least one selected from tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methylphenyldimethoxysilane, vinyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, and diphenyldimethoxysilane.

[0035] Preferably, the catalyst is at least one selected from formic acid, acetic acid, propionic acid, and citric acid.

[0036] This application provides a method for preparing the ceramic coating that blocks the migration of heavy metal ions, comprising:

[0037] Step 1: Mix component A and component B evenly to obtain a mixture of component A and component B;

[0038] Step 2: Add component C to the mixture from Step 1 and roll it at 900-1500 rpm for 6-12 hours to obtain a mixture of components A, B and C.

[0039] Step 3: Add component D to the mixture from step 2 and mix thoroughly to obtain the ceramic coating that blocks the migration of heavy metal ions.

[0040] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0041] Further optimization involves rolling and maturing the mixture at a speed of 1200–1300 rpm for 6–12 hours in step 2 to obtain a mixture of components A, B, and C.

[0042] Preferably, in step 2, the curing temperature is 15–25°C and the curing time is 8–12 hours.

[0043] In step 3, the amount of component D is 4% to 10% of the total mass of components A, B, and C.

[0044] In the preparation of ceramic coatings, components A, C, and D are prepared separately and stored separately. When coating preparation is required, each component is prepared into a ceramic coating according to the preparation method.

[0045] The preparation process of component A includes: mixing all raw materials in component A evenly, then grinding them to a fineness of 20 μm, and filtering them through a 400-mesh filter cloth to obtain component A. Grinding can be performed using a high-speed grinding and dispersing machine. More preferably, grinding to a fineness of 25 μm and filtering through a 300-mesh filter cloth to obtain component A.

[0046] The preparation process of component C includes: mixing and dispersing all raw materials of component C evenly to obtain component C.

[0047] The preparation process of component D includes: mixing and dispersing all raw materials of component D evenly to obtain component D.

[0048] Use as soon as possible after all components are mixed; do not store for extended periods.

[0049] This application also provides a ceramic coating, wherein the ceramic coating is sprayed onto the surface of an object with a coating thickness of 36-50 micrometers, baked at 180-200°C for 10-30 minutes, and then baked at 280-300°C for 10-30 minutes to obtain the ceramic coating.

[0050] This application introduces graphene oxide into ceramic coatings. Due to the large number of active reactive groups such as hydroxyl (-OH) and carboxyl (-COOH) on the surface of graphene oxide, graphene oxide will undergo a ternary copolymerization reaction with hydroxyl-containing silica particles in siloxanes and silica sols under the action of a catalyst during the curing process of the ceramic coating. After high-temperature baking, condensation and dehydration are carried out to form a very dense ceramic coating. At the same time, based on the special sheet-like structure of graphene oxide, it is further beneficial to block the migration of heavy metal ions.

[0051] This application also provides an application of the ceramic coating that blocks the migration of heavy metal ions in the preparation of non-stick cookware, including frying pans, woks, saucepans, rice cookers, ovens, and range hoods.

[0052] The ceramic coating provided in this application can effectively prevent the migration of heavy metal ions, while improving the salt water resistance and detergent resistance of the ceramic coating prepared by the ceramic coating. The ceramic coating with added graphene oxide also has better thermal conductivity and antibacterial properties, saves more energy, and is safer and more hygienic. Attached Figure Description

[0053] Figure 1 This is a diagram illustrating the reaction mechanism of siloxane hydrolysis to silanol.

[0054] Figure 2 This is a schematic diagram illustrating the mechanism of the coating formation through the ternary copolymerization reaction of graphene oxide with silica sol and silanol. Detailed Implementation

[0055] The technical solution of this application will be further described in detail below through specific embodiments. It should be understood that the implementation of this application is not limited to the following embodiments, and any modifications and / or alterations made to this application will fall within the protection scope of this application.

[0056] In this application, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0057] Unless otherwise specified, the reagents used in the following examples can be purchased from a regular biochemical reagent store.

[0058] The reagents used in each example are described below:

[0059] Graphene oxide: purchased from Beijing Deco Island Gold Technology Co., Ltd., with a particle size of 5-15 μm and a purity of ≥99%;

[0060] Alkaline silica sol: Produced by Shandong Baite New Materials Co., Ltd., with a pH value of 9-11, a solid content of 35-37%, and a particle size range of 30-40nm;

[0061] Dispersant BYK-ET3032: purchased from BYK Chemical Technology Consulting (Shanghai) Co., Ltd.;

[0062] Cobalt green (heat-resistant pigment): purchased from Foshan Zhengnian New Materials Co., Ltd.;

[0063] Leveling agent BYK-333, purchased from BYK Chemical Technology Consulting (Shanghai) Co., Ltd.;

[0064] Defoamer TEGO902W was purchased from Bodi Shanghai Trading Co., Ltd.

[0065] The testing methods for various properties of ceramic non-stick coatings are as follows:

[0066] 1. Coating thickness: Refer to the test method in 6.2.3 of GB / T32095.2-2015.

[0067] 2. Coating adhesion: Tested using a cross-cut adhesion tester according to the method in GB / T9286-1998;

[0068] 3. Egg non-stick test: Refer to the test method in 4.2.1 of GB / T32095.2-2015. The specific test method is as follows:

[0069] Wash the frying pan with warm water (above 60℃) and a neutral detergent, then rinse thoroughly with clean water and dry. Heat the pan to 150-170℃, crack a fresh egg and place it in the pan. Once the protein has mostly solidified, remove the egg completely using a silicone spatula. Continue frying eggs in this manner to evaluate the non-stick properties. A non-stick performance of Grade II or higher is considered a completed cycle. Continue until the non-stick performance no longer meets Grade II standards, at which point the test ends, and the number of fried eggs is recorded.

[0070] For evaluation methods, please refer to section 5.1.1 of GB / T32095.2-2015.

[0071]

[0072] 4. Saltwater Resistance Non-stick Test Method for Coating: Prepare a 5% (w / w) salt solution using purified water, boil for 2 hours, then discard the solution. Perform a non-stick test on an egg and evaluate the non-stick properties. A non-stick performance of Grade II or higher is considered a completed cycle. Repeat the test until the non-stick performance can no longer reach Grade II. End the test and record the number of cycles.

[0073] 5. Coating detergent-resistant non-stick test method: Prepare a 2% mass fraction washing powder solution with pure water, keep it at 80 °C for 1 hour, then pour it out, rinse it clean with water, and then conduct an egg non-stick test to evaluate the non-stick property. If the non-stick property reaches level II or above, it is regarded as completing one cycle. Repeat the test until the non-stick property cannot reach the level II standard, end the test, and record the number of cycles.

[0074] 6. The test for heavy metal ion migration of the coating refers to the test method in GB4806.10-2016 "National Food Safety Standard - Coatings and Coatings for Food Contact". The specific test method is as follows: Pour the acetic acid immersion solution with a volume fraction of 4% into the pan after boiling (the coating on the surface of the pan is the coating to be tested), then put it into an oven at 100 °C, change the acetic acid every 4 hours, for a total of three times. After the three tests are completed, detect the total metal ion migration amount of the third immersion solution. It is required that the detected total metal ion migration amount ≤ 10 mg / dm

[0082] , and if there are no phenomena such as cracking, blistering, and peeling on the coating surface, it is regarded as passing the test; otherwise, it is regarded as failing the test.

[0075] Examples 1 - 5

[0076] A preparation method of a ceramic coating for blocking heavy metal ion migration is as follows:

[0077] (1) Preparation of components A, B, C, and D:

[0078] Preparation of component A: Add 67 kg of silica sol, 4 kg of silicon carbide (filler), 4 kg of ceramic powder (filler), 6 kg of barite (filler), 1 kg of dispersant BYK-ET3032 (dispersant), 10 kg of titanium dioxide (heat-resistant pigment), and 8 kg of cobalt green (heat-resistant pigment) into the stirring container in sequence, stir and disperse at a speed of 1300 rpm for 30 minutes, then grind through a grinder until the fineness of the material reaches below 15 μm, and filter through a 300-mesh filter cloth to obtain component A;

[0079] Preparation of component B: Take graphene oxide as component B;

[0080] Preparation of component C: Mix 50 kg of methyltrimethoxysilane (siloxane), 5 kg of methylphenyldimethoxysilane (siloxane), 3 kg of dimethyl silicone oil (silicone oil), and 2 kg of formic acid (catalyst) evenly to obtain component C;

[0081] Preparation of component D: Mix 8 kg of isopropyl alcohol (solvent), 1 kg of leveling agent, and 1 kg of defoaming agent evenly to obtain component D.

[0082] The formulations of Examples 1-5 and Comparative Example 1 are shown in Table 1. Comparative Example 1 is a conventional ceramic coating without the addition of graphene oxide. Except for the absence of component B, i.e., the absence of graphene oxide, the addition amounts of other components and the preparation methods are the same as those of Examples 1-5.

[0083] Table 1

[0084] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Component A 100kg 100kg 100kg 100kg 100kg 100kg Component B 1kg 2kg 3kg 4kg 5kg / Component C 60kg 60kg 60kg 60kg 60kg 60kg Component D 10kg 10kg 10kg 10kg 10kg 10kg

[0085] The preparation method of ceramic coatings includes the following steps:

[0086] Components A and B were mixed evenly according to the weight ratios in Table 1. Then, component C was added to the mixture of A and B according to the proportions shown in Table 1. The mixture was stirred at 1300 rpm for 10 hours at room temperature using a high-speed disperser (rolling curing) to ensure complete hydrolysis, condensation, cross-linking, and curing of the siloxane, silica sol, and graphene oxide. Finally, component D was added to the mixture of components A, B, and C, and stirred evenly to obtain the ceramic coating that blocks the migration of heavy metal ions.

[0087] The preparation method of ceramic coating includes the following steps:

[0088] The prepared ceramic coating was sprayed onto a frying pan using a pneumatic spraying method, with the coating thickness controlled to be 36-50 micrometers. The pan was first baked at 180℃ for 10 minutes, and then baked at 280℃ for 10 minutes to obtain a long-term high-temperature resistant non-stick ceramic coating.

[0089] The ceramic coatings prepared in Examples 1-5 and Comparative Example 1 were subjected to relevant performance tests, and the test results are shown in Table 2.

[0090] Table 2

[0091]

[0092]

[0093] As can be seen from Table 2, compared with Comparative Example 1, the ceramic coatings with added graphene oxide in Examples 1-5 have a significant effect on reducing the migration of heavy metal ions, and at the same time have a significant effect on improving the coating's resistance to salt water and detergent.

[0094] As can be seen from Examples 2 to 5, when the amount of graphene oxide added is more than 2% of component A, it has the effect of blocking the migration of heavy metal ions.

[0095] As can be seen from Examples 3 to 5, when the amount of graphene oxide added is more than 3% of component A, it not only has the effect of blocking the migration of heavy metal ions, but also controls the amount of heavy metal ion migration to a very low level; at the same time, the coating's resistance to salt water and detergent also reaches a very high level.

[0096] Examples 3-5 also show that as the amount of graphene oxide added is further increased, the reduction in the migration of heavy metal ions is not very obvious, and the improvement in the coating's resistance to salt water and detergent is not very obvious.

[0097] Considering the relatively high cost of graphene oxide, it is best to choose an addition amount of 3% to 4% of component A. At this addition amount, the prepared graphene oxide ceramic coating not only effectively blocks the migration of heavy metal ions, but also controls the migration of heavy metal ions to a very low level. It also exhibits excellent salt water resistance and detergent resistance, and offers good cost-effectiveness.

[0098] This application describes a ceramic coating that can block the migration of heavy metal ions by adding graphene oxide to ordinary ceramic coatings. Because graphene oxide has many active reactive groups such as carboxyl and hydroxyl groups on its surface, silica sol and siloxane will undergo a ternary polymerization reaction with graphene oxide under the action of a catalyst to form a very dense ceramic coating. In addition, the special layered structure of graphene oxide can further block the migration of heavy metal ions. Moreover, the dense ceramic coating can prevent corrosion from salt water and detergents, thus exhibiting better salt water resistance and detergent resistance.

[0099] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0100] The ceramic coating capable of blocking the migration of heavy metal ions and its preparation method provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A ceramic coating that blocks the migration of heavy metal ions, characterized in that, The ceramic coating comprises component A, component B, component C, and component D, with a weight ratio of 100:1 to 10:40 to 80:7 to 15. The raw material composition of component A by weight is as follows: Component B is graphene oxide; The raw material composition of component C is as follows by weight: 90-99 parts of siloxane; 1-10 parts silicone oil; 1-6 parts of catalyst; The raw material composition of component D is as follows by weight: Solvent 50-90 parts; Leveling agent 2-20 parts; 0-9 parts of defoamer.

2. The ceramic coating for blocking the migration of heavy metal ions as described in claim 1, characterized in that, The weight ratio of component A to component B is 100:2 to 5.

3. The ceramic coating for blocking the migration of heavy metal ions as described in claim 1, characterized in that, The weight ratio of component A to component C is 100:45 to 65.

4. The ceramic coating for blocking the migration of heavy metal ions as described in claim 1, characterized in that, The weight ratio of component A to component D is 100:8 to 12.

5. The ceramic coating for blocking the migration of heavy metal ions as described in claim 1, characterized in that, The silica sol is an alkaline silica sol with a solid mass fraction of 30% to 45% and a particle size of 15 to 60 nm.

6. The ceramic coating for blocking the migration of heavy metal ions as described in claim 1, characterized in that, The graphene oxide is a single-layer graphene oxide with a particle size of 3–15 μm.

7. The ceramic coating for blocking the migration of heavy metal ions as described in claim 1, characterized in that, The siloxane is at least one of tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methylphenyldimethoxysilane, vinyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, and diphenyldimethoxysilane.

8. The ceramic coating for blocking the migration of heavy metal ions as described in claim 1, characterized in that, The catalyst is at least one of formic acid, acetic acid, propionic acid, and citric acid.

9. The method for preparing the ceramic coating for blocking the migration of heavy metal ions as described in any one of claims 1 to 8, characterized in that, include: Step 1: Mix component A and component B evenly to obtain a mixture of component A and component B; Step 2: Add component C to the mixture from Step 1 and roll it at 900-1500 rpm for 6-12 hours to obtain a mixture of components A, B and C. Step 3: Add component D to the mixture from step 2 and mix thoroughly to obtain the ceramic coating that blocks the migration of heavy metal ions.

10. A ceramic coating, characterized in that, The ceramic coating obtained by the preparation method of claim 9 is sprayed onto the surface of an object with a coating thickness of 36-50 micrometers, baked at 180-200°C for 10-30 minutes, and then baked at 280-300°C for 10-30 minutes to obtain the ceramic coating.

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