Non-stick cookware, non-stick coating and method for making same

Abstract

The application provides a non-stick coating, a non-stick cookware, a non-stick coating and a preparation method thereof. The non-stick coating comprises a soluble salt solution and a framework silicate in a granular form dispersed in the soluble salt solution, wherein the soluble salt solution comprises a soluble salt and a solvent, the weight percentage of the framework silicate is 30-40%, the weight percentage of the soluble salt is 0.5-2%, and the balance is the solvent. According to the non-stick coating, a non-stick coating with good initial non-stickiness, persistent non-stickiness and binding force can be obtained.

Description

Technical Field

[0001] This application relates to the field of non-stick cookware technology, and more specifically, to a non-stick coating for cookware, non-stick cookware, non-stick coating layer and its preparation method. Background Technology

[0002] Fluoropolymer coatings are common non-stick coatings in this field. However, non-stick coatings made with fluoropolymer coatings are easily damaged by spatulas and are prone to aging or decomposition due to high temperatures during use. These problems have seriously affected the service life of cookware coatings formed with fluoropolymer coatings, resulting in generally poor long-lasting non-stick properties.

[0003] Therefore, developing non-stick coatings for cookware that combine initial non-stick properties with long-lasting non-stick properties remains a problem that needs to be solved. Summary of the Invention

[0004] Therefore, the purpose of this application is to provide a non-stick coating for cookware, non-stick cookware, non-stick coating, and a method for preparing the same, so as to solve the problem that existing non-stick coatings cannot simultaneously possess both initial non-stick and long-lasting non-stick properties.

[0005] According to a first aspect of this application, a non-stick coating is provided for cookware, wherein the non-stick coating comprises a soluble salt solution and a framework silicate in particulate form dispersed in the soluble salt solution, wherein the soluble salt solution comprises a soluble salt and a solvent, and based on 100% of the total weight of the non-stick coating, the framework silicate accounts for 30%-40% by weight, the soluble salt accounts for 0.5%-2% by weight, and the remainder is solvent.

[0006] In some embodiments, the framework silicate includes at least one of the quartz group, feldspar group, feldspar-like group, and zeolite group; and / or The particle size of the framework silicate is in the range of 10 nm to 1 μm.

[0007] In some embodiments, the soluble salt includes at least one of soluble nitrate, soluble sulfate, and soluble chloride.

[0008] In some embodiments, the metal cations in the soluble salt include at least two of sodium ions, magnesium ions, lithium ions, potassium ions, aluminum ions, iron ions, calcium ions, and zinc ions.

[0009] In some embodiments, the non-stick coating further includes a suspending agent and / or a flux, wherein the weight percentage of the suspending agent in the non-stick coating is 5%-10%, and the weight percentage of the flux in the non-stick coating is 2%-5%.

[0010] In some embodiments, the suspending agent comprises clay and / or bentonite; and / or the fluxing agent comprises at least one of borax, fluorite, cryolite, barium carbonate, and zinc oxide.

[0011] According to a second aspect of this application, a method for preparing a non-stick coating is provided, wherein the preparation method includes: A non-stick coating is applied to the substrate to form a slurry layer; The slurry layer is sintered at a preset temperature to form the non-stick coating. Wherein, the non-stick coating is the non-stick coating according to any one of claims 1-6.

[0012] In some embodiments, the preset temperature is in the range of 800℃-1300℃.

[0013] In some embodiments, the framework silicate particles in the slurry layer are α-quartz, which forms α-cristobalite after sintering, and the α-cristobalite is present in the non-stick coating.

[0014] According to a third aspect of this application, a non-stick coating is provided for cookware, wherein the non-stick coating has an amorphous structure, and the non-stick coating is formed by the non-stick coating material provided according to the above embodiments or the non-stick coating is prepared by the preparation method of the non-stick coating provided according to the above embodiments.

[0015] In some embodiments, the non-stick coating includes at least one of the following features: The volume percentage of the amorphous phase in the non-stick coating is in the range of 50%-75%. The surface energy of the non-stick coating is between 10 dynes and 40 dynes; The porosity of the non-stick coating is 0.1% to 0.3%; The Vickers hardness of the non-stick coating is 1200 HV to 1500 HV; The thickness of the non-stick coating is 50 μm to 200 μm.

[0016] According to a fourth aspect of this application, a non-stick cookware is provided, wherein the non-stick cookware includes a non-stick coating formed by the non-stick coating provided in the above embodiments, or includes a non-stick coating prepared by the method for preparing the non-stick coating provided in the above embodiments. Attached Figure Description

[0017] The above and / or other features and aspects of the inventive concept will become clear and readily understood through the description of the embodiments in conjunction with the accompanying drawings.

[0018] Figure 1This is a schematic diagram of a framework silicate structure provided according to an embodiment of this application; Figure 2 This is a schematic diagram of the cross-sectional structure of the cookware provided in the embodiment of this application after being cut along the thickness direction.

[0019] Symbol explanation: 100. Non-stick cookware; 110. Substrate; 120. Non-stick coating; 130. Base coat. Detailed Implementation

[0020] Example embodiments of the inventive concept will now be described in more detail. While example embodiments of the inventive concept are described below, it should be understood that the inventive concept can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the inventive concept to those skilled in the art.

[0021] Fluoropolymer coatings are common non-stick coatings in this field. However, non-stick coatings made with fluorine-based coatings are easily damaged by spatulas and are prone to aging or decomposition due to high temperatures during use. These problems have seriously affected the service life of coatings formed with fluorine-based coatings. In addition, the raw materials used to form fluorine-based coatings are becoming increasingly restricted.

[0022] Currently, no material with a lower surface energy than fluoropolymer coatings has been found, but the demand for non-stick coatings in the cookware industry remains constant. Ceramic coatings are now considered a potential replacement for fluoropolymer coatings. Ceramic coatings are liquid coatings with silicone oil as the main non-stick component. While the initial non-stick properties of the resulting coating may be close to those of fluoropolymer coatings, the silicone oil is quickly consumed by the high temperatures during cooking, causing the non-stick effect to be lost. Therefore, ceramic coatings have poor long-lasting non-stick properties.

[0023] With the development of the non-stick industry, solid spraying materials based on metals (e.g., iron, stainless steel, low-carbon steel, high-carbon steel, cast iron, and copper) or ceramics (e.g., titanium oxide, titanium nitride, titanium carbide, iron(II,III) oxide, iron oxide, ferrous oxide, aluminum oxide, chromium oxide, and nickel oxide) have emerged. These materials can form non-stick coatings, a technology known as "coating-free non-stick technology." Here, "coating-free" simply means that it does not use organic coatings such as fluorinated or ceramic coatings. While the coating formed by these spraying materials is wear-resistant, cookware with this coating only exhibits non-stick properties when oily, and its initial non-stick performance is poor. It typically requires modification with materials possessing good non-stick properties, such as polysiloxanes or fluorinated materials, to meet national standards for initial non-stick performance. Furthermore, the non-stick properties of these materials decrease rapidly after wear, and residual polysiloxanes can have a counterproductive effect on non-stick performance, making it even worse than before modification.

[0024] As can be seen from the above, existing non-stick coatings struggle to achieve both initial and long-lasting non-stick properties. Therefore, developing new non-stick coatings that combine both initial and long-lasting non-stick properties plays a crucial role in the cookware manufacturing industry.

[0025] The basic structure of silicate materials is a silicon-oxygen tetrahedron, in which silicon atoms occupy the center and four oxygen atoms occupy the four corners. These tetrahedra, depending on their different arrangements, form silicates with various structures, such as framework silicates and layered silicates, which have completely different properties and structures.

[0026] Specifically, layered silicates refer to silicates with a layered crystal structure, similar to that of graphite. Existing technologies include techniques for storing oil within the layered pores of layered silicates to form a non-stick coating.

[0027] Framework silicates, as materials for cookware coatings, possess a certain degree of porosity and wear resistance, but they are prone to breakage or cracking under alternating hot and cold environments, posing a severe challenge to cookware coatings. To address this technical problem, solutions need to be found to improve the resistance of framework silicate coatings to alternating hot and cold conditions.

[0028] The inventors discovered that materials containing other metal cations can be introduced into framework silicates, thereby ensuring the toughness and heat resistance of the resulting non-stick coating.

[0029] According to a first aspect of this application, a non-stick coating for cookware is provided, wherein the non-stick coating comprises a soluble salt solution and a framework silicate dispersed in the soluble salt solution in particulate form, wherein the soluble salt solution comprises a soluble salt and a solvent, and based on 100% of the total weight of the non-stick coating, the framework silicate accounts for 30%-40% by weight, the soluble salt accounts for 0.5%-2% by weight, and the remainder is solvent.

[0030] According to the non-stick coating provided in this application embodiment, a mixed slurry formed by dispersing a predetermined amount of framework silicate particles in a soluble salt solution is used as a non-stick coating for cookware. In the non-stick coating, soluble sodium salt can enter the framework structure of the silicate particles, and the framework silicate particles can be uniformly dispersed. In the process of manufacturing the non-stick coating, this non-stick coating is first applied to the substrate to form a slurry layer, which can ensure the uniform dispersion of silicate particles. Then, the slurry layer is sintered at a preset temperature for a preset time. During this process, as the solvent is evaporated, the soluble salt in the non-stick coating precipitates from the solvent and is uniformly dispersed with the framework silicate particles. The soluble salt can melt and "enter" the space left by the volume expansion of the framework silicate after the crystal transformation, and chemically combine with the framework silicate to form a non-stick coating. Thus, the non-stick coating has low surface energy and a high degree of amorphization, thereby ensuring the non-stick performance of the cookware (initial non-stick and long-term non-stick).

[0031] According to this application, the non-stick coating is a liquid coating, formed by uniformly mixing at least two soluble salts and framework silicates in a solvent and stirring thoroughly. During the manufacturing process of the non-stick coating, the metal cations ionized from the soluble salts can "enter" the spaces left by the volume expansion of the framework silicates after their crystal transformation, acting as fillers. This reduces the thermal expansion rate of the non-stick coating, thus ensuring its resistance to thermal shock and its toughness under cooking conditions.

[0032] The following will primarily describe the components of the non-stick coating according to this application.

[0033] According to this application, framework silicate particles are a class of compounds with a unique structure, mainly composed of silicon and oxygen atoms, forming a stable framework structure. As the main component for providing non-stick coatings, they belong to inorganic materials, are stable in properties and have high hardness. Therefore, when used to form non-stick coatings for cookware, they have superior high temperature resistance and scratch resistance compared to fluoropolymers.

[0034] According to this application, framework silicates can be crystalline materials or materials with a certain degree of amorphousness, such as materials with an amorphous phase volume ratio in the range of 1%-15%, with the remainder being crystalline phase. In the embodiments of this application, "framework" refers to the crystal structure of the silicate, not the stacking form of the material. Furthermore, framework silicates themselves have a porous structure, including at least one of the quartz group, feldspar group, feldspar-like group, and zeolite group. Specifically, the quartz group includes α-quartz; the feldspar group includes at least one of alkali feldspar, plagioclase, and barium feldspar; the feldspar-like group includes at least one of nepheline, leucite, scapolite, sodalite, and lapis lazuli; and the zeolite group includes at least one of zeolite, metazeolite, and analcime. In a preferred embodiment, the framework silicate is a quartz group. The non-stick coating formed by the quartz group has the greatest volume change and the greatest spatial change at the high temperature of subsequent sintering at a preset temperature. Therefore, in the final non-stick coating formed by various framework silicates, the non-stick coating formed by quartz has the highest amorphous phase volume ratio. The specific amorphous phase volume ratio will be described in detail in the following embodiments. Figure 1 This is a schematic diagram of a framework silicate structure provided according to an embodiment of this application. For example... Figure 1 As shown, a frame-like structure can be seen.

[0035] According to this application, the framework silicate is granular, meaning it exists as fine powdery particles. In this application, the smaller the average particle size of the framework silicate particles, the better. This is because, on the one hand, the smaller the framework silicate particles, the more uniform and sufficient the soluble salt can contact with them, allowing the soluble salt to fully penetrate the framework silicate during subsequent sintering, resulting in a higher amorphous phase volume ratio, which is beneficial for non-stickiness; on the other hand, the larger the framework silicate particles, the worse the surface smoothness of the final product, which is detrimental to the product's appearance. However, considering both manufacturing cost and non-stick properties, in some embodiments, the average particle size of the framework silicate particles is in the range of 10nm-1μm. Preferably, if the average particle size of the framework silicate particles is greater than 1μm, the particles are too large. On the one hand, this will reduce the "reaction" efficiency between the soluble salt and the framework silicate particles, resulting in a lower amorphous phase volume ratio in the final non-stick coating. On the other hand, the final non-stick coating will have a larger surface roughness, affecting the smoothness of the surface. If the average particle size of the framework silicate particles is less than 10nm, the particle size is too small, the particle processing cost is too high, and the final product cost is affected.

[0036] In some embodiments, the particles are spherical, near-spherical, columnar, etc. Considering the particle packing performance, flow performance and surface activity, in preferred embodiments, the particles are spherical or near-spherical.

[0037] In existing technologies, the application of framework silicates requires purification steps. Taking quartz as an example, before use, quartz undergoes physical crushing, physical screening, and chemical purification. Chemical purification typically employs three processes: acid washing, leaching, and thermal chlorination. Acid washing and leaching are effective at removing physically bonded inclusions, while thermal chlorination can remove more difficult-to-remove lattice-bound impurities. Acid leaching is frequently used to remove physically bonded thin-film iron on the surface of quartz particles and physically bonded iron impurities within the particles. Through these methods, high-purity quartz of 99.991% can be prepared.

[0038] According to this application, framework silicates can be used directly without chemical purification. Specifically, framework silicate ores are processed through grinding, color sorting, magnetic separation, and flotation to obtain framework silicate particles. Then, using an electrolytic melting process, the obtained framework silicate particles are placed in an electrolytic melting tank. The high temperature generated by electrolytic melting (taking quartz as an example, the electrolytic melting temperature is 1800-2000℃, held for 8-12 hours, i.e., between the melting and boiling points) causes low-melting-point impurities to volatilize, thus removing impurities. Simultaneously, the metal cations within the framework silicate particles change from physical bonding to chemical bonding. At high temperatures, the metal cations enter the intergranular spaces (for example, at high temperatures, Si-Si bonds connect the quartz crystals, "squeezing out" vacancies for impurity elements; simultaneously, the quartz intergranular spaces are relatively large at high temperatures, allowing metal cations to enter and utilize their own metal cations), and chemically combine with the framework silicate particles to form the framework silicate of this application. That is, the framework silicate of this application can be the reaction product of silicate with framework structure and metal cation.

[0039] In this application, the framework silicate powder obtained by the above method is a material with a certain amorphous phase volume ratio. For example, the amorphous phase volume ratio is generally in the range of 1%-15%. Framework silicates with such an amorphous phase volume ratio can provide a good non-stick base for the coating they form. In some embodiments, the framework silicate particles can be pre-treated to obtain framework silicate powder with a higher amorphous phase volume ratio. Specifically, the framework silicate particles are sintered at 800℃-1300℃ for 3-5 hours, and then cooled at a preset cooling rate to obtain framework silicate powder with a preset amorphous phase volume ratio. The preset cooling rate can be achieved by cooling the framework silicate particles under cold air conditions; for example, the preset cooling rate can be 50℃ / s-100℃ / s. According to this application, the non-stick particles after pre-treatment of the framework silicate particles have an amorphous phase volume ratio in the range of 2%-18%.

[0040] According to this application, the framework silicate particles obtained by crushing framework silicate rocks can be materials with an amorphous phase volume fraction ranging from 1% to 15%. Framework silicate particles obtained by sintering the crushed particles followed by rapid cooling have an amorphous phase volume fraction ranging from 2% to 18%. In general, the amorphous phase volume fraction of the framework silicate particles according to this application can be in the range of 1% to 18%. Framework silicate particles generally have poor non-stick properties, therefore, it is necessary to improve their non-stick properties through appropriate methods.

[0041] Salts are compounds composed of metal cations and acid radicals, belonging to ionic compounds. Generally, soluble salts are classified into three types: readily soluble, moderately soluble, and sparingly soluble. It should be noted that, according to this application, soluble salts refer to readily soluble salts, and correspondingly, soluble salt solutions include readily soluble salt solutions. In non-stick coatings, the weight percentage of soluble salts is 0.5%-2%. During coating formation, on the one hand, they can enter the framework silicate and chemically combine with it, causing the overall structure to develop towards amorphization; on the other hand, they help regulate the dispersion stability of framework silicate particles and improve the curing or adhesion properties of the coating during coating formation.

[0042] The soluble salt can be any salt that does not affect the performance of the coating or food safety. In some embodiments, taking different metal cations as examples, the soluble salt solution includes at least one of soluble sodium salt solution, soluble magnesium salt solution, soluble aluminum salt solution, soluble iron salt solution, soluble calcium salt solution, and soluble zinc salt solution. Taking different acid anions as examples, the soluble salt solution includes at least one of nitrate, sulfate, and chloride salts. As an example, the soluble salt solution includes at least one of sodium chloride, magnesium chloride, aluminum chloride, ferric chloride, calcium chloride, zinc chloride, sodium sulfate, magnesium sulfate, aluminum sulfate, ferric sulfate, calcium sulfate, zinc sulfate, sodium nitrate, magnesium nitrate, aluminum nitrate, ferric nitrate, calcium nitrate, and zinc nitrate.

[0043] According to this application, a method for manufacturing a soluble salt solution is provided. Specifically, a soluble salt (wherein the soluble salt is an ionic compound) can be dissolved in a predetermined volume of solvent at a predetermined mass to form a soluble salt solution. As an example, the soluble salt solution includes a soluble salt as a solute and a solvent, wherein the solvent is a carrier for non-stick coatings and is used to adjust the viscosity and flowability of the coating during application. The choice of solvent is based on its volatility, its solubility in structural silicates, and its compatibility with cookware substrates. Common solvents may include water, alcohols, or other organic solvents.

[0044] According to this application, the maximum volume of framework silicate expansion at high temperatures is fixed. Therefore, the maximum amount of soluble salt "absorbed" per unit type of each framework silicate at a specific high temperature is also fixed. Thus, there is a one-to-one correspondence between the amount of soluble salt in the soluble salt solution and the weight ratio of the framework silicate particles. For example, in non-stick coatings, the weight ratio of framework silicate to soluble salt is (30-40):(0.5-2). In this way, the metal cations forming the soluble salt are just suitable for interfering with the crystal structure in the framework silicate particles. Excessive crystallization will not affect the overall strength of the non-stick coating, nor will insufficient crystallization prevent the formation of a disordered structure in the non-stick coating.

[0045] In some embodiments, when the framework silicate particles in the non-stick coating are within a preset weight percentage range (i.e., 30%-40%) and the weight of the soluble salt is constant, if the mass percentage of the soluble salt solution is greater than 2%, the efficiency of "entering" the interior of the framework silicate particles is low, and the disordered state of the framework silicate particles does not increase significantly; furthermore, excessive soluble salt precipitated from the soluble salt solution will lead to insufficient strength of the non-stick coating, making it prone to problems such as peeling; if the mass percentage of the soluble salt solution is less than 0.5%, the amorphous content is too low, which cannot meet the requirements for thermal shock resistance and mechanical strength as a cooking coating.

[0046] In some embodiments, when the mass percentage of the soluble salt solution is within a preset range (i.e., 0.5% - 2%) and the weight of the soluble salt is constant, if the weight percentage of the framework silicate particles is greater than 40%, the disordered state of the framework silicate particles does not increase significantly, resulting in a lack of significant increase in the volume percentage of the amorphous phase in the final non-stick coating; if the weight percentage of the framework silicate particles is less than 30%, the excessive salt content in the final non-stick coating leads to insufficient coating strength and problems such as peeling.

[0047] To improve the mixing uniformity of the non-stick coating and ensure that suspended matter in the non-stick coating does not easily settle, according to this application, the non-stick coating also includes a suspending agent, the weight percentage of which can be 5%-10%. In an exemplary embodiment, the suspending agent includes clay and / or bentonite.

[0048] Framework silicates typically have a melting point between 1200°C and 1700°C. To reduce the temperature required to fire the slurry layer into a non-stick coating and lower process costs, according to this application, the non-stick coating may further include a flux, with the flux comprising 2%-5% by weight in the non-stick coating. In an exemplary embodiment, the flux includes at least one of borax, fluorite, cryolite, barium carbonate, and zinc oxide, thereby enabling the firing temperature to be maintained within the range of 800°C-1300°C, thus lowering the melting point of the framework silicate.

[0049] According to this application, both the suspending agent and the flux are in particulate form. In some embodiments, the average particle size is in the range of 10 nm to 1 μm. If the average particle size is greater than 1 μm, the particles are too large. On the one hand, this reduces the "reaction" efficiency between the soluble salt and the framework silicate particles, resulting in a lower amorphous phase volume ratio in the final non-stick coating. On the other hand, the final non-stick coating has a larger surface roughness, affecting the smoothness of the surface. If the average particle size is less than 10 nm, the particle size is too small, the particle processing cost is too high, and the final product cost is affected.

[0050] According to a second aspect of this application, a non-stick coating is provided for cookware, wherein the non-stick coating has an amorphous structure and is formed by sintering the non-stick coating provided in the above embodiments at a preset temperature.

[0051] According to this application, a non-stick coating 120 having a preset amorphous phase volume ratio can at least partially cover the inner surface of the substrate 110; in other words, the non-stick coating 120 can cover part or all of the inner surface of the substrate 110. The non-stick coating 120 may be formed by spraying the non-stick coating provided in the embodiments of this application, thereby having good non-stick properties, improved hardness, and wear resistance.

[0052] According to this application, the non-stick coating is a material with a preset amorphous phase volume ratio. Due to the special composition / content of the non-stick coating of this application, a non-stick coating 120 with a preset amorphous phase volume ratio can be formed by controlling the spraying process.

[0053] In some embodiments, the volume percentage of the amorphous structure of the non-stick coating is in the range of 50%-60%.

[0054] In some embodiments, the surface energy of the non-stick coating is from 10 dynes to 40 dynes, the porosity of the non-stick coating is from 0.1% to 0.3%, the Vickers hardness of the non-stick coating is from 1200 HV to 1500 HV, and the thickness of the non-stick coating is from 50 μm to 200 μm.

[0055] According to a third aspect of this application, a method for preparing a non-stick coating is provided, wherein the method includes: Step S101: Apply the non-stick coating onto the substrate to form a slurry layer.

[0056] Step S102: Sinter the slurry layer at a preset temperature to form a non-stick coating; wherein the non-stick coating includes a soluble salt solution and a framework silicate dispersed in the soluble salt solution in particulate form, wherein the soluble salt solution includes soluble salt and solvent, and based on the total weight of the non-stick coating as 100%, the weight percentage of framework silicate is 30%-40%, the weight percentage of soluble salt is 0.5%-2%, and the remainder is solvent.

[0057] In the embodiments of this application, the non-stick coating is a reaction product of framework silicate and metal cations in soluble salt.

[0058] The following describes a method for preparing a non-stick coating according to this application, with reference to specific embodiments.

[0059] A non-stick coating is applied to form a slurry layer. According to this application, the non-stick coating may be the non-stick coating described in the first aspect of this application, which will not be repeated here.

[0060] According to this application, the non-stick coating can be applied to the substrate by brushing or by air spraying. In an exemplary embodiment, the parameters for air spraying are: selecting a spray gun with a nozzle diameter of 1.5~2.0mm, adjusting the air pressure to 0.3~0.4MPa, and setting the spray gun angle to 40°-50°.

[0061] Sintering the slurry layer to form a non-stick coating According to this application, the soluble salts and framework silicates in the slurry layer are uniformly dispersed. The sintering process of the slurry layer includes heating, holding, and cooling stages. During the heating stage, the high temperature causes the water in the slurry layer to evaporate, but the soluble salts and framework silicates still exist in a uniformly dispersed form. As the water evaporates, the soluble salts crystallize and precipitate. During the holding stage, the previously precipitated soluble salts crystallize and melt, and can "enter" the space left by the volume expansion of the framework silicates after the crystal transformation. Under the continuous high temperature, the two fuse together, and the metal cations in the soluble salt solution form chemical bonds with the framework silicate particles, forming chelates with a higher amorphousness than the framework silicate particles. During the cooling stage, the soluble salts and framework silicates form a disordered structure. During the volume expansion of the framework silicates, the more soluble salts enter, the higher the degree of disorder, and the greater the proportion of the amorphous phase.

[0062] In this embodiment, the non-stick coating is equivalent to the reaction product of various metal cations and framework silicates, specifically a product of the chemical combination of metal cations and framework silicates, which can be referred to as a silicate material with both an amorphous and framework structure. Here, the framework structure in the silicate material originates from framework silicates. In some embodiments, framework silicates are chemically modified by various metal cations to form reaction products through chelation. The reaction products are composite metal cation silicate materials with an amorphous structure, thereby improving the surface properties of the framework silicates themselves and obtaining the desired low surface energy effect.

[0063] According to this application, the cookware with the slurry layer is first placed in a sintering furnace and heated to 600°C at a heating rate of 5°C / min-7.5°C / min. During this stage, the moisture in the non-stick coating forming the slurry layer can be quickly drained. In this process, as the moisture in the soluble salt solution continuously evaporates, the soluble salt can precipitate from the soluble salt solution. It should be noted that a portion of the soluble salt is located in the pore structure of the framework silicate, and another portion of the soluble salt is located in the framework silicate... Between the salt particles, the temperature is then increased to 800℃-1300℃ at a rate of 1.0℃ / min-2.0℃ / min. During this stage, the framework silicate expands in volume, and the framework silicate and the precipitated soluble salt can melt. Next, the temperature is held at 800℃-1300℃ for 0.5h-1h, allowing the framework silicate and the precipitated soluble salt to melt and intermingle as much as possible. Subsequently, the furnace is cooled to room temperature, where the framework silicate and the precipitated soluble salt chemically combine to form corresponding reaction products. Furthermore, the expanded framework silicate shrinks in volume during cooling, releasing stress and ensuring good adhesion of the non-stick coating.

[0064] According to this application, during sintering at a preset temperature within the range of 800℃-1300℃, the framework silicates in the slurry layer expand in volume. Metal cations from the soluble salt solution can then enter the framework silicates and chemically combine with them to form framework silicate chelates. This causes the material to develop towards disorder, increasing the amorphous content of the resulting coating. In an exemplary embodiment, the amorphous content of the formed coating is 50%-70%.

[0065] It should be noted that in the framework silicates of this application, the framework silicates other than α-quartz only undergo volume changes. Under sintering conditions, they will enter soluble salts, which will eventually increase the amorphous content. When α-quartz particles are used as framework silicate particles in non-stick coatings, they will also undergo volume changes at cooking temperatures, which will further increase the amorphous content under cooking conditions.

[0066] According to this application, the framework silicate particles in the slurry layer are α-quartz. After sintering, the volume of α-quartz will expand and undergo a phase transformation to form α-cristobalite. α-cristobalite is a different phase variant of α-quartz and still belongs to the quartz family.

[0067] The following describes a method for preparing a non-stick coating according to this application, using quartz as an example.

[0068] In some embodiments, the framework silicate particles in the non-stick coating are α-quartz, which can form a slurry layer with α-quartz as the framework silicate particles. The α-quartz in the slurry layer is transformed into α-cristobalite after sintering, and the α-cristobalite exists in the non-stick coating.

[0069] Typical cooking temperatures are generally between 180°C and 300°C. The transformation temperature between α-cristobalite and β-cristobalite is 180°C-270°C. Therefore, α-cristobalite and β-cristobalite will transform within the cooking temperature range. In some embodiments, the non-stick coating including α-cristobalite will transform into β-cristobalite at the cooking temperature, with a volume change rate of 2.5%-2.8%, resulting in a volume reduction. Although substances have been added to the intergranular spaces of the quartz in the non-stick layer, and the volume change is already very small, the crystal form is still changing. This transformation process involves a disordered and unstable state, further increasing the disorder within the non-stick coating. Consequently, the amorphous proportion increases during cooking. When cooking ends and the temperature drops below 180°C, β-cristobalite will transform into α-cristobalite, and the volume of the non-stick coating will increase. During use, the amorphous phase volume ratio of the non-stick coating including α-cristobalite can be 70%-75%.

[0070] According to a fourth aspect of this application, a non-stick cookware is provided, wherein the non-stick cookware includes a non-stick coating formed by the non-stick paint provided in the above embodiments, or includes the non-stick coating provided in the above embodiments, or includes a non-stick coating prepared according to the preparation method of the non-stick coating provided in the above embodiments. Therefore, it possesses all the beneficial effects of the above embodiments, which will not be elaborated further here.

[0071] Figure 1 This is a schematic cross-sectional view of the cookware provided in the embodiment of this application after being cut along the thickness direction. (Refer to...) Figure 1 The non-stick cookware 100 may include a substrate 110 and a non-stick coating 120.

[0072] In some embodiments, the substrate 110 is a metal substrate or a ceramic substrate. For example, the substrate 110 may be made of conventional metal or ceramic materials.

[0073] According to this application, rack-like silicate particles belong to a class of ceramic materials and have relatively poor adhesion to metal substrates. In the case where the substrate is metal, in order to increase the adhesion between the non-stick coating and the substrate, in some embodiments, the cookware further includes a base coat 130, which is made of metal and disposed between the substrate 110 and the non-stick coating 120. However, if the substrate is ceramic, the base coat 130 is not required.

[0074] In an exemplary embodiment, the undercoat can be prepared by thermal spraying or cold spraying of a metal material. The undercoat material can be selected from conventional metal materials and ceramic materials, such as at least one of titanium, titanium alloy, iron, iron alloy, aluminum, aluminum alloy, zinc, zinc alloy, copper, copper alloy, zirconium, and zirconium alloy.

[0075] The present application will now be described in detail with reference to specific embodiments, but the scope of protection of the present application is not limited to the embodiments.

[0076] Example 1 The cookware according to Example 1 is manufactured by the following method.

[0077] Step S10: Prepare the cookware base. Specifically, the steps for preparing the cookware base include deep drawing a stainless steel sheet, surface cleaning with alkaline wash to remove oil, drying, and sandblasting to obtain a cookware base with a thickness of 1.5cm.

[0078] Step S20: Prepare the non-stick coating. α-quartz particles are used as the framework silicate, and ferric chloride solution is used as the soluble salt solution. Specifically, the non-stick coating consists of ferric chloride solution and α-quartz particles with an average particle size of 10 nm-1 μm dispersed in the ferric chloride solution. Based on the total weight of the non-stick coating (100%), α-quartz accounts for 30% of the weight, ferric chloride accounts for 0.5% of the weight, and the remainder is water.

[0079] Step S30: A slurry layer with a thickness of 68 μm is formed.

[0080] Step S40: Sinter the slurry layer at 1000°C to form a non-stick coating. Specifically, the cookware with the slurry layer is placed in a sintering furnace and heated to 600°C at a heating rate of 6°C / min to complete the heating stage. Then, it is heated to 1000°C at a heating rate of 1.5°C / min, and then held at 1000°C for 1 hour to complete the holding stage. Subsequently, it is cooled to room temperature with the furnace to complete the cooling stage, thereby obtaining a non-stick coating with a thickness of 65 μm on the inner surface of the cookware substrate. The non-stick coating serves as the coating of the cookware, thus completing the manufacture of the cookware of Example 1.

[0081] Example 2 Except in step S20, where a different non-stick coating (based on the total weight of the non-stick coating being 100%, α-quartz accounting for 30% of the weight, ferric chloride accounting for 2% of the weight, and the remainder being water) is used to replace the non-stick coating of Example 1, the cookware of Example 2 is manufactured using the same method as in Example 1.

[0082] Example 3 Except in step S20, where a different non-stick coating (based on the total weight of the non-stick coating being 100%, α-quartz accounting for 40% of the weight, ferric chloride accounting for 0.5% of the weight, and the remainder being water) is used to replace the non-stick coating of Example 1, the cookware of Example 3 is manufactured using the same method as in Example 1.

[0083] Example 4 Except in step S20, where a different non-stick coating (based on the total weight of the non-stick coating being 100%, α-quartz accounting for 40% of the weight, ferric chloride accounting for 2% of the weight, and the remainder being water) is used to replace the non-stick coating of Example 1, the cookware of Example 4 is manufactured using the same method as in Example 1.

[0084] Example 5 Except in step S20, where a different non-stick coating (the non-stick coating is composed of a ferrous chloride solution and α-quartz in particulate form dispersed in the ferrous chloride solution, wherein, based on the total weight of the non-stick coating being 100%, the weight percentage of α-quartz is 30%, the weight percentage of ferrous chloride is 0.5%, and the balance is water) is used to replace the non-stick coating of Example 1, the cookware of Example 5 is manufactured using the same method as in Example 1.

[0085] Example 6 Except in step S20, where a different non-stick coating (the non-stick coating is composed of a mixed solution of ferrous chloride and ferric chloride and α-quartz with an average particle size of 10 nm-1 μm dispersed in the ferrous chloride solution, wherein, based on the total weight of the non-stick coating being 100%, the weight percentage of α-quartz is 30%, the weight percentage of ferrous chloride and ferric chloride is 0.5%, and the balance is water) is used to replace the non-stick coating of Example 1, the cookware of Example 6 is manufactured using the same method as in Example 1.

[0086] Example 7 Except in step S20, where a different non-stick coating (the non-stick coating is composed of a mixed solution of ferrous chloride, ferric chloride and potassium chloride and α-quartz with an average particle size of 10 nm-1 μm dispersed in the ferrous chloride solution, wherein, based on the total weight of the non-stick coating being 100%, the weight percentage of α-quartz is 30%, the weight percentage of ferrous chloride, ferric chloride and potassium chloride is 0.5%, and the balance is water) is used to replace the non-stick coating of Example 1, the cookware of Example 7 is manufactured using the same method as in Example 1.

[0087] Example 8 Except in step S20, where a different non-stick coating (the non-stick coating is composed of ferric sulfate solution and α-quartz with an average particle size of 10 nm-1 μm dispersed in ferric chloride solution, wherein, based on the total weight of the non-stick coating as 100%, the weight percentage of α-quartz is 30%, the weight percentage of ferric sulfate is 0.5%, and the balance is water) is used to replace the non-stick coating of Example 1, the cookware of Example 8 is manufactured using the same method as in Example 1.

[0088] Example 9 Except in step S20, where a different non-stick coating (the non-stick coating is composed of ferric nitrate solution and α-quartz with an average particle size of 10 nm-1 μm dispersed in ferric chloride solution, wherein, based on the total weight of the non-stick coating being 100%, the weight percentage of α-quartz is 30%, the weight percentage of ferric nitrate is 0.5%, and the balance is water) is used to replace the non-stick coating of Example 1, the cookware of Example 9 is manufactured using the same method as in Example 1.

[0089] Example 10 Except in step S20, in which a different non-stick coating (composed of sodium chloride solution and α-quartz with an average particle size of 10 nm-1 μm dispersed in sodium chloride solution, wherein, based on the total weight of the non-stick coating as 100%, the weight percentage of α-quartz is 30%, the weight percentage of sodium chloride is 0.5%, and the balance is water) is used to replace the non-stick coating of Example 1, the cookware of Example 10 is manufactured using the same method as in Example 1.

[0090] Example 11 Except in step S20, where feldspar particles are used instead of α-quartz particles in Example 1 to form a non-stick coating, the cookware of Example 11 is manufactured using the same method as in Example 1.

[0091] Example 12 Except in step S20, where zeolite particles are used instead of α-quartz particles in Example 1 to form a non-stick coating, the cookware of Example 12 is manufactured using the same method as in Example 1.

[0092] Example 13 Except in step S20, where feldspar-like particles are used instead of α-quartz particles in Example 1 to form a non-stick coating, the cookware of Example 13 is manufactured using the same method as in Example 1.

[0093] Example 14 Except in step S20, where α-quartz particles are placed in an electrolytic melting tank beforehand, and the electrolytic melting temperature is controlled at 1800°C and held for 10 hours, and then the treated α-quartz particles are formed into a non-stick coating, the cookware of Example 14 is manufactured using the same method as in Example 1.

[0094] Example 15 Except in step S20, where clay with an average particle size of 10 nm-1 μm and a weight percentage of 3% is added to the non-stick coating of Example 1 to form the non-stick coating of this example, the cookware of Example 15 is manufactured using the same method as in Example 1.

[0095] Example 16 Except for step S20, in which borax with an average particle size of 10nm-1μm and a weight percentage of 3% is added to the non-stick coating of Example 1 to form the non-stick coating of this example, the cookware of Example 16 is manufactured using the same method as in Example 1.

[0096] Example 17 Except for step S40, in which the temperature is increased to 800°C at a rate of 1.5°C / min and then held at 800°C for 1 hour to complete the holding stage, the cookware of Example 17 is manufactured using the same method as in Example 1.

[0097] Example 18 Except in step S40, where the temperature is increased to 1300°C at a rate of 1.5°C / min and then held at 1300°C for 1 hour to complete the holding stage, the cookware of Example 18 is manufactured using the same method as in Example 1.

[0098] Comparative Example 1 A quartz pot of the same thickness as in Example 1 (formed by die casting of quartz powder) was used as the cookware for Comparative Example 1.

[0099] Comparative Example 2 A coating with a thickness of 65 μm was formed on the cookware substrate in step S10 by plasma spraying using α-quartz with an average particle size of 10 nm-1 μm, thereby obtaining the cookware of Comparative Example 2.

[0100] Comparative Example 3 A coating with a thickness of 65 μm was formed on the cookware substrate in step S10 by plasma spraying using zeolite particles with an average particle size of 10 nm-1 μm, thereby obtaining the cookware of Comparative Example 3.

[0101] Comparative Example 4 Feldspar particles with an average particle size of 10 nm to 1 μm were used to form a coating with a thickness of 65 μm on the cookware substrate in step S10 by plasma spraying, thereby obtaining the cookware of Comparative Example 4.

[0102] Comparative Example 5 Feldspar-like particles with an average particle size of 10 nm to 1 μm were used to form a coating with a thickness of 65 μm on the cookware substrate in step S10 by plasma spraying, thereby obtaining the cookware of Comparative Example 5.

[0103] Comparative Example 6 Except in step S20, where a different coating (the coating of Comparative Example 6 is composed of water and α-quartz with an average particle size of 10 nm-1 μm dispersed in water, wherein, based on the total weight of the non-stick coating being 100%, the weight percentage of α-quartz is 30%, and the remainder is water) is used to replace the non-stick coating of Example 1, the cookware of Comparative Example 6 is manufactured using the same method as in Example 1.

[0104] Comparative Example 7 Except in step S20, where a different coating (the coating of Comparative Example 7 is composed of water and zeolite particles with an average particle size of 10 nm-1 μm dispersed in water, wherein the weight percentage of zeolite particles is 30% based on the total weight of the non-stick coating as 100%, and the remainder is water) is used to replace the non-stick coating of Example 1, the cookware of Comparative Example 7 is manufactured using the same method as in Example 1.

[0105] Comparative Example 8 Except in step S20, where a different coating (the coating of Comparative Example 8 is composed of water and feldspar-like particles with an average particle size of 10 nm-1 μm dispersed in water, wherein the feldspar-like particles account for 30% of the total weight of the non-stick coating, and the remainder is water) is used to replace the non-stick coating of Example 1, the cookware of Comparative Example 8 is manufactured using the same method as in Example 1.

[0106] Test methods and evaluation criteria, test results The degree of amorphization of the framework silicates of Examples 1 to 18 and Comparative Examples 1 to 8 was tested, and the test results are shown in Table 1 below.

[0107] I. Testing Methods and Evaluation Criteria Amorphousness testing method: XRD testing was used, followed by conventional full-spectrum fitting analysis to obtain the amorphousness of the sample. The steps of the conventional full-spectrum fitting method are as follows: First, a crystalline phase with the same chemical structure as the amorphous phase is found. It is assumed that the amorphous phase is a tiny grain of this crystalline phase, and this crystalline phase can be used to establish a model of the peak position and intensity of the amorphous phase. Second, the spectrum of the pure amorphous phase is fitted to determine the grain size and microstrain. Finally, the grain size and microstrain are fixed, and this phase is included in the traditional Rietveld quantitative calculation to obtain the volume fraction of the amorphous phase (i.e., the degree of amorphousness).

[0108] Table 1 Results Test Table

[0109] The cookware obtained in Examples 1-18 and Comparative Examples 1-8 were subjected to the following performance tests, and the results are recorded in Table 2 below. The specific performance test methods are as follows.

[0110] I. Testing Methods and Evaluation Criteria 1. Amorphousness Test Method Amorphousness testing method: XRD testing was used, and the amorphousness of the sample was analyzed and calculated using the conventional full-spectrum fitting method. The steps of the conventional full-spectrum fitting method are as follows: First, a crystalline phase with the same chemical structure as the amorphous phase was found. It was assumed that the amorphous phase was a tiny grain of this crystalline phase, and this crystalline phase could be used to establish a model of the peak position and intensity of the amorphous phase. Second, the spectrum of the pure amorphous phase was fitted to determine the grain size and microstrain. Finally, the grain size and microstrain were fixed, and this phase was included in the traditional Rietveld quantitative calculation to obtain the volume fraction of the amorphous phase (i.e., the amorphousness) and recorded in Table 2 below.

[0111] 2. Initial non-stickiness test method Initial non-stick test method: GB / T32095.2-2015 Test method for non-stick properties of fried eggs. This method is an initial non-stick test, which is divided into grades I, II and III. Grade I has the best non-stick properties, and grade III has the worst non-stick properties.

[0112] 3. Durable non-stick test method Durable non-stick test method: GB / T32388-2015 Durable non-stick test method, the unit is the number of cycles. The higher the number of cycles, the longer the life. 500 cycles are used to evaluate the non-stick result once. Record the number of cycles until the use reaches level III.

[0113] 4. Hardness Testing and Evaluation Standards The Vickers hardness test method was used to measure the Vickers hardness of the cookware coating, with the unit of hardness value being HV. A higher hardness value indicates a harder sample, stronger resistance to abrasion from metal spatulas and food, and less susceptibility to wear, thus resulting in a longer lifespan for the non-stick coating. Generally, a hardness of at least 200 HV is desirable for non-stick coatings.

[0114] 5. Surface Energy Testing and Evaluation Standards At a temperature of 20°C, the contact angles of water and ethylene glycol on the sample surfaces were measured using a SINDIN SDC-200SH contact angle meter according to the goniometry method, and the surface energy of the samples was calculated using the OWRK method. Here, the sample refers to the non-stick coating of the cookware obtained in the examples and comparative examples.

[0115] For surface energy testing, the smaller the better; it is desirable for the measured surface energy value of the sample to be no greater than 100 dynes.

[0116] 6. Steel ball impact test and evaluation standards: A 500g steel ball is dropped freely from a certain height from the bottom of the sample, with 5cm intervals between drops. The non-stick coating on the inner surface is observed to see if it cracks or peels off. The height at which it cracks or peels off is recorded. The higher the height, the stronger the impact resistance of the coating. The height should not be less than 20cm, as this can characterize the adhesion of the coating.

[0117] II. Test Results Table 2 Results Test Table

[0118] As can be seen from Tables 1 and 2, the amorphous phase changes of the materials and coatings in the comparative examples are not significant. However, the non-stick coating according to this application shows a more significant increase in the proportion of amorphous phase after sintering, especially quartz. This is because quartz crystals have a large intergranular space at high temperatures, allowing metal cations to enter and utilize their own metal cations, resulting in a more pronounced amorphous transformation. Therefore, the initial non-stick and long-term non-stick properties of the non-stick coating formed by the non-stick material can be guaranteed. In addition, the non-stick coating according to this application not only possesses good non-stick properties but also good adhesion.

[0119] While the invention has been specifically shown and described with reference to exemplary embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made herein without departing from the spirit and scope of the invention as defined by the claims and their equivalents. The embodiments should be considered in a descriptive sense and not for limiting purposes only. Therefore, the scope of the invention is not defined by the specific embodiments thereof, but by the claims, and all differences within that scope will be construed as included in the invention.

Claims

1. A method for preparing a non-stick coating for cookware, characterized in that, The preparation method includes: A non-stick coating is applied to a substrate to form a slurry layer. The non-stick coating includes a soluble salt solution and a framework silicate in particulate form dispersed in the soluble salt solution. The soluble salt solution includes a solvent and a soluble salt containing metal cations. Based on 100% of the total weight of the non-stick coating, the framework silicate accounts for 30%-40% by weight, the soluble salt accounts for 0.5%-2% by weight, and the remainder is solvent. The slurry layer is sintered at a preset temperature, causing the framework silicate and soluble salt to react, thereby forming the non-stick coating composed of the reaction products.

2. The method for preparing the non-stick coating according to claim 1, characterized in that, The preset temperature is in the range of 800℃-1300℃.

3. The method for preparing the non-stick coating according to claim 1, characterized in that, The framework silicate particles in the slurry layer are α-quartz, which forms α-cristobalite after sintering, and the α-cristobalite exists in the non-stick coating.

4. The method for preparing the non-stick coating according to claim 1, characterized in that, The framework silicates include at least one of the quartz group, feldspar group, feldspar-like group, and zeolite group; and / or The particle size of the framework silicate is in the range of 10 nm to 1 μm.

5. The method for preparing the non-stick coating according to claim 1, characterized in that, The soluble salt includes at least one of soluble nitrate, soluble sulfate, and soluble chloride.

6. The method for preparing the non-stick coating according to claim 5, characterized in that, The metal cations in the soluble salt include at least two of the following: sodium ions, magnesium ions, lithium ions, potassium ions, aluminum ions, iron ions, calcium ions, and zinc ions.

7. The method for preparing the non-stick coating according to claim 1, characterized in that, The non-stick coating further includes a suspending agent and / or a flux, wherein the weight percentage of the suspending agent in the non-stick coating is 5%-10%, and the weight percentage of the flux in the non-stick coating is 2%-5%.

8. The method for preparing the non-stick coating according to claim 7, characterized in that, The suspending agent includes clay and / or bentonite; and / or the fluxing agent includes at least one of borax, fluorite, cryolite, barium carbonate, and zinc oxide.

9. A non-stick coating for cookware, characterized in that, The non-stick coating has an amorphous structure and is prepared by the method for preparing a non-stick coating according to any one of claims 1-8.

10. The non-stick coating according to claim 9, characterized in that, The non-stick coating includes at least one of the following characteristics: The volume percentage of the amorphous phase in the non-stick coating is in the range of 50%-75%. The surface energy of the non-stick coating is between 10 dynes and 40 dynes; The porosity of the non-stick coating is 0.1% to 0.3%; The Vickers hardness of the non-stick coating is 1200 HV to 1500 HV; The thickness of the non-stick coating is 50 μm to 200 μm.

11. A non-stick cookware, characterized in that, The non-stick cookware includes the non-stick coating according to claim 9 or 10.

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