Self-cleaning glaze, self-cleaning antique brick and preparation method thereof

Abstract

The application relates to the technical field of building ceramics, in particular to a self-cleaning glaze, a self-cleaning antique brick and a preparation method thereof, which comprises the following raw materials: hydrophilic frit, kaolin, quartz, calcite, albite and nano bovine bone ash, and the chemical composition of the nano bovine bone ash comprises Ca 10 (PO4)6(OH)2 and CaO; the hydrophilic frit comprises the following raw materials: calcite, wollastonite, kaolin, aluminum oxide and quartz. The self-cleaning glaze provided by the application realizes excellent and persistent self-cleaning under the premise of reducing production cost, and solves the technical problems of poor self-cleaning timeliness and high production cost in the prior art.

Description

Technical Field

[0001] This invention relates to the field of building ceramics technology, and in particular to a self-cleaning glaze, a self-cleaning antique brick, and a method for preparing the same. Background Technology

[0002] Antique-style bricks, as an artistic building material that blends classical aesthetics with modern craftsmanship, are highly favored by consumers for their unique antique glaze effect, rich color layers, and strong historical charm. They are widely used in home decoration, commercial venues, and cultural tourism scenic spots.

[0003] To ensure the antique effect of antique-style bricks, their surfaces are usually designed to be uneven. While this uneven surface increases their anti-slip properties, it also easily accumulates dust, oil stains, and other dirt. Ordinary wiping is insufficient for thorough cleaning, and long-term accumulation not only affects the appearance but may also breed bacteria. Traditional cleaning methods typically rely on chemical cleaners or high-pressure water guns, which are not only inefficient but may also cause wear or corrosion to the brick surface.

[0004] To overcome the above-mentioned defects, existing technologies typically coat the surface of antique bricks with a hydrophilic self-cleaning coating, forming a hydrophilic self-cleaning coating on the surface of the antique bricks. This allows water to spread rapidly upon contact with the coating surface (i.e., the static contact angle between water and the coating is small) and form a uniform water film. The water film can penetrate into the interface between dirt and the coating, thereby reducing the adhesion of dirt. Furthermore, under the action of gravity, the continuously flowing water film can carry away and remove dirt from the surface of the antique bricks, achieving a self-cleaning effect. However, the above methods have the following drawbacks: (1) The self-cleaning coating has poor aging resistance. It is prone to aging when exposed to ultraviolet rays, rain and temperature changes for a long time, which leads to the gradual failure of the self-cleaning function and poor self-cleaning durability; (2) The bonding force between the hydrophilic self-cleaning coating and the antique brick substrate is limited. It is easy to peel off under frequent friction or temperature stress, which will also reduce the durability of hydrophilic self-cleaning; (3) The surface of existing antique bricks generally does not have hydrophilic self-cleaning properties. It is necessary to apply an additional layer of hydrophilic self-cleaning coating to make it have hydrophilic self-cleaning properties. However, applying an additional hydrophilic self-cleaning coating will easily increase production costs and is not conducive to large-scale promotion and application.

[0005] Therefore, how to achieve persistent self-cleaning properties while reducing production costs has become an urgent technical challenge. Summary of the Invention

[0006] The purpose of this invention is to propose a self-cleaning glaze that achieves excellent and long-lasting self-cleaning properties while reducing production costs, thus solving the technical problems of poor self-cleaning timeliness and high production costs in the prior art.

[0007] The second objective of this invention is to provide a method for preparing self-cleaning antique bricks. The method is simple, easy to operate, and ensures that the resulting self-cleaning antique bricks not only have excellent and long-lasting self-cleaning properties, but also help reduce costs.

[0008] The third objective of this invention is to provide a self-cleaning antique brick prepared by the above-mentioned method for preparing self-cleaning antique bricks. The static contact angle of the self-cleaning antique brick is 5-9° when it is not soaked in boiling water, and 12-16° when it is soaked in boiling water for 30 days, thus exhibiting excellent and long-lasting self-cleaning properties.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] A self-cleaning glaze comprises the following raw materials: hydrophilic frit, kaolin, quartz, calcite, albite, and nano-sized bovine bone ash, wherein the chemical composition of the nano-sized bovine bone ash includes Ca. 10 (PO4)6(OH)2 and CaO;

[0011] The hydrophilic frit comprises the following raw materials: calcite, wollastonite, kaolin, aluminum oxide, and quartz.

[0012] Furthermore, the particle size of the nano-bovine bone ash is <20nm.

[0013] Furthermore, the chemical composition of the nano-bovine bone ash, calculated by mass percentage, includes Ca. 10 (PO4)6(OH)2 60-75%, CaO 15-25%, MgO 5-8%, Na2O 3-5%, and K2O 1-2%.

[0014] Furthermore, calculated by mass parts, it includes the following raw materials: 40-50 parts hydrophilic frit, 4-10 parts kaolin, 18-32 parts quartz, 9-15 parts calcite, 4-10 parts albite, and 2-6 parts nano bovine bone ash;

[0015] The hydrophilic frit, calculated by mass fraction, comprises the following raw materials: 15-19 parts calcite, 15-19 parts wollastonite, 32-52 parts kaolin, 15-19 parts alumina, and 5-11 parts quartz.

[0016] A method for preparing self-cleaning antique-style tiles, using the aforementioned self-cleaning glaze, includes the following steps:

[0017] A. Calcite, wollastonite, kaolin, aluminum oxide and quartz are mixed evenly, calcined and then water-quenched to obtain a hydrophilic frit;

[0018] B. After mixing the hydrophilic frit, kaolin, quartz, calcite, albite and nano-bovine bone ash evenly, add sodium methyl cellulose, sodium hexametaphosphate and water and ball mill, then sieve to obtain the self-cleaning glaze; wherein, according to the mass percentage, the amount of water added is 33-50% of the dry material of the self-cleaning glaze.

[0019] C. Apply self-cleaning glaze to the surface of the body with a textured surface, dry it, and fire it in a kiln to obtain self-cleaning antique bricks.

[0020] Further, in step A, the calcination temperature curve of the hydrophilic frit is as follows: the temperature is increased from room temperature to 1530°C at a heating rate of 8-10°C / min, and then held for 35-45 minutes.

[0021] Furthermore, in step B, the specific gravity of the self-cleaning glaze is 1.15 to 1.2, and the residue of the self-cleaning glaze after passing through a 325-mesh sieve is 0.2 to 0.4% by mass percentage.

[0022] Furthermore, in step C, the thickness of the self-cleaning glaze is 0.05–0.1 mm.

[0023] Furthermore, in step C, the firing temperature curve of the self-cleaning antique brick includes a preheating section, a preheating section, a high-temperature section, a heat preservation section, a transition section, a rapid cooling section, a slow cooling section, a strong cooling section, and a final cooling section.

[0024] The preheating section takes 3 to 6 minutes to raise the temperature from room temperature to 750°C.

[0025] The temperature rises from 750°C to 1050°C in the initial temperature range, taking 1.2 to 4 minutes.

[0026] The high-temperature section rises from 1050℃ to 1145℃ in 5–8 minutes;

[0027] The insulation section is maintained at 1145℃ for 4.5–10 minutes.

[0028] The transition section cools the temperature from 1145℃ to 950℃ in 1.8–5 minutes.

[0029] The rapid cooling section reduces the temperature from 950°C to 630°C in 2–3 minutes.

[0030] The slow cooling section reduces the temperature from 630°C to 610°C in 5–10 minutes.

[0031] The rapid cooling section reduces the temperature from 610°C to 210°C in 3.5–6 minutes.

[0032] The final cooling section cools the temperature from 310°C to 200°C in 4–8 minutes.

[0033] A self-cleaning antique brick is prepared using the above-mentioned method for preparing self-cleaning antique bricks. The static contact angle of the self-cleaning antique brick without being soaked in boiling water is 5-9°, and the static contact angle after being soaked in boiling water for 30 days is 12-16°.

[0034] The technical solution provided by this invention may include the following beneficial effects:

[0035] 1. This technical solution forms a micro-nano rough structure through multiple mechanisms. This micro-nano rough structure significantly increases the microscopic roughness of the self-cleaning glaze surface, thereby increasing its actual specific surface area. The increased specific surface area exposes more surface atoms or molecules. These surface atoms or molecules, due to the presence of unsaturated chemical bonds (such as dangling bonds), are in a high-energy unstable state. The accumulation of high-energy surface atoms can increase the surface energy of the glaze. Simultaneously, the micro-nano rough structure increases the local curvature of the self-cleaning glaze surface, raising the chemical potential of surface atoms, which is beneficial for improving the surface energy of the self-cleaning glaze.

[0036] 2. This technical solution, through the synergistic effect of the above-mentioned multiple aspects, enriches the surface of the self-cleaning glaze with hydroxyl groups, strengthens the hydrogen bond adsorption capacity between the self-cleaning glaze and water molecules, improves the hydrophilicity of the self-cleaning glaze surface, and makes it easier for water to spread on the glaze surface and form a uniform water film, thereby removing and cleaning the dirt on the surface of the antique bricks, and achieving the purpose of improving the self-cleaning effect.

[0037] 3. The nano-bovine bone ash in the formulation system contains hydroxyapatite. The phosphate ions in hydroxyapatite carry three negative charges and can strongly attract hydrogen ions from water molecules (H+). + They also form a hydrogen bond network through electrostatic interactions. Furthermore, the electrostatic interaction between polyvalent phosphate ions and water is stronger than that between ordinary hydroxyl groups and water, making water molecules spread more easily, significantly enhancing the surface wettability of the self-cleaning glaze, and improving the self-cleaning properties of the glaze. Detailed Implementation

[0038] This technical solution provides a self-cleaning glaze, comprising the following raw materials: hydrophilic frit, kaolin, quartz, calcite, albite, and nano-bovine bone ash, wherein the chemical composition of the nano-bovine bone ash includes Ca. 10 (PO4)6(OH)2 and CaO;

[0039] The hydrophilic frit comprises the following raw materials: calcite, wollastonite, kaolin, aluminum oxide, and quartz.

[0040] In order to achieve long-lasting self-cleaning properties while reducing costs, this technical solution proposes a self-cleaning glaze, the raw materials of which include hydrophilic frit, kaolin, quartz, calcite, albite and nano-boned ox bone ash, and the raw materials of the hydrophilic frit include calcite, wollastonite, kaolin, alumina and quartz.

[0041] First, during the calcination process, a series of chemical reactions occur in the raw materials of the self-cleaning glaze formulation: calcite (mainly calcium carbonate) decomposes to generate calcium oxide; wollastonite (chemically calcium metasilicate) decomposes to generate calcium oxide and silicon dioxide; kaolin decomposes to generate silicon dioxide and aluminum oxide; and albite decomposes to generate silicon dioxide, aluminum oxide, and sodium oxide. The combined effects of these reaction products, along with the introduction of silicon dioxide by quartz, calcium oxide by nano-bone ash, and the aluminum oxide inherent in the formulation itself, result in a self-cleaning glaze layer after calcination, primarily composed of calcium oxide, silicon dioxide, aluminum oxide, and sodium oxide. This is because calcium oxide (with a surface tension of 470 × 10⁻⁶)... -3 N / M), silica (surface tension of 290×10 -3 N / M), aluminum oxide (surface tension 380×10 -3 N / M) and sodium oxide (surface tension of 150×10 -3 The surface tension of N / M is much greater than that of water (surface tension is 73×10). -3 (N / m). Therefore, the surface tension (i.e., surface energy) of the self-cleaning glaze is significantly higher than that of water, giving the self-cleaning glaze a higher surface energy. It should be noted that for the description of the surface properties of liquids and solids, liquids are generally described using surface tension, while solids are generally described using surface energy. Therefore, in the following description, the surface tension of the glaze will be described using surface energy.

[0042] Furthermore, in this technical solution's formulation system, the calcium oxide, aluminum oxide, and silicon dioxide introduced by the calcination of the raw materials react to form anorthite crystals (CaAl2Si2O8), while aluminum oxide and silicon dioxide can react to form mullite (3Al2O3·2SiO2). During the precipitation process, due to anisotropic growth and the presence of dislocation defects, some of these crystals exist in the form of microcrystals. The precipitated microcrystals are usually irregular in shape, such as polyhedra, needles, and plates. When these irregularly shaped microcrystals precipitate from the glaze glass phase (matrix), they form a micro-nano rough structure on the glaze surface.

[0043] Furthermore, due to its small particle size and large specific surface area, nano-bovine bone ash possesses high surface energy. This high surface energy drives its spontaneous adsorption and accumulation on the glaze surface. Since the decomposition initiation temperature of nano-bovine bone ash is approximately 1400℃, and the calcination temperature in existing kilns is generally below 1200℃, even if the formulation contains fluxes such as zinc oxide to promote its melting, only partial decomposition occurs. The skeletal structure of its nanoparticles is preserved, forming a micro-nano rough structure on the glaze surface.

[0044] In summary, this technical solution creates a micro-nano rough structure through multiple mechanisms. This micro-nano rough structure significantly increases the micro-roughness of the self-cleaning glaze surface, thereby increasing its actual specific surface area. The increased specific surface area exposes more surface atoms or molecules. These surface atoms or molecules, due to the presence of unsaturated chemical bonds (such as dangling bonds), are in a high-energy unstable state. The accumulation of these high-energy surface atoms increases the surface energy of the glaze. Simultaneously, the micro-nano rough structure increases the local curvature of the self-cleaning glaze surface, raising the chemical potential of surface atoms, which is beneficial for increasing the surface energy of the self-cleaning glaze. It should be noted that only the micro-nano rough structure exhibiting a microscopic structure can affect the surface energy of the glaze layer. The millimeter- or even centimeter-level unevenness on the surface of antique-style tiles is a macroscopic scale that only affects the mechanical anti-slip properties of the tile and does not change the chemical properties of the glaze surface. In addition, even though millimeter- or centimeter-level embossing effects may contain ordinary micro-rough structures, these micro-rough structures are generally unlikely to reach the critical scale of "significant increase in local curvature". This means that the contribution of these ordinary micro-roughness to surface energy may be limited, and millimeter-level embossing textures mainly affect the mechanical anti-slip properties of the brick.

[0045] Furthermore, during calcination, calcite not only decomposes to form calcium oxide but also releases carbon dioxide gas. Under the current firing cycle of 30–60 minutes in kilns, the escaped carbon dioxide gas leaves behind submicron-sized pores, forming a micro / nano porous structure. This micro / nano porous structure significantly increases the actual surface area of ​​the glaze, which also helps to improve the surface energy of the glaze.

[0046] In summary, through the aforementioned multiple effects, the self-cleaning glaze layer acquires a high surface energy, allowing water to spread more easily on its surface and form a uniform water film. This water film can carry away and remove dirt from the surface of the antique-style tiles, thus achieving self-cleaning properties.

[0047] Secondly, calcium oxide is composed of calcium ions (Ca... 2+ ) and oxygen ions (O 2- Ionic compounds formed by ionic bonds readily react with moisture (such as ambient water vapor adsorbed on the surface of raw materials, crystal water bound between glaze components, or moisture introduced during the process) to generate calcium hydroxide (CaO+H2O→Ca(OH)2). The surface of calcium hydroxide contains a large number of highly polar hydroxyl groups.

[0048] Simultaneously, acidic oxides (such as silicon dioxide) in the formulation system react with basic oxides (such as calcium oxide and sodium oxide) to form a silicate network structure (i.e., a glassy phase). The alkali metal ions provided by the alkali metal oxides (such as calcium oxide and sodium oxide) can break the bridging oxygen bonds between silicon-oxygen tetrahedra in the silicate network structure, causing the silicate network structure to depolymerize and generate negatively charged non-bridging oxygen (Si-O). -Meanwhile, calcium ions in calcium oxide, due to their high charge density, strongly attract the negative charge of non-bridging oxygen and interact strongly with it, further weakening the bridging bonds between adjacent silicon-oxygen tetrahedra in the silicate network structure. This promotes the breakage of more bridging oxygens, generating new non-bridging oxygens, thus producing a large amount of non-bridging oxygen. The non-bridging oxygen dipoles can react with moisture (such as environmental water vapor adsorbed on the surface of the raw materials, crystal water bound between glaze components, or equilibrium moisture introduced during the process) to generate hydroxyl groups, increasing the number of hydroxyl groups on the surface of the self-cleaning glaze layer.

[0049] In addition, the hydroxyapatite (Ca) contained in nano-bovine bone ash 10 Phosphate ions in (PO4)6(OH)2 can undergo limited hydrolysis with water to generate hydrolysis products such as hydrogen phosphate or dihydrogen phosphate. The hydroxyl groups in these hydrolysis products migrate to the surface of the self-cleaning glaze at high temperatures and are directionally enriched through chemical bonding or hydrogen bonding with surface defects, thereby significantly increasing the number of hydroxyl groups on the glaze surface.

[0050] Furthermore, both micro / nano porous structures and micro / nano rough structures can improve the performance of Ti. 4+ Components that form hydroxyl groups, such as non-bridging oxygen, are more fully exposed on the glaze surface, thus providing a richer number of reactive sites. This increase in reactive sites allows Ti... 4+ Non-bridging oxygen and other compounds can react more fully with water to form more hydroxyl groups.

[0051] In summary, through the synergistic effect of the above-mentioned multiple aspects, the surface of the self-cleaning glaze is enriched with hydroxyl groups, which enhances the hydrogen bond adsorption capacity between the self-cleaning glaze and water molecules, improves the hydrophilicity of the self-cleaning glaze surface, and makes it easier for water to spread on the glaze surface and form a uniform water film, thereby carrying away and removing dirt from the surface of the antique bricks, achieving the purpose of improving the self-cleaning effect.

[0052] Furthermore, during the cooling process of the self-cleaning glaze layer, due to the tendency to minimize energy, positively charged calcium ions and negatively charged non-bridging oxygen atoms accumulate on the surface of the self-cleaning glaze layer and interact to generate calcium-non-bridging oxygen dipoles, thus enriching the surface of the self-cleaning glaze layer with calcium-non-bridging oxygen dipoles. Due to the strong polarization effect of calcium ions, these dipoles cause the local electron cloud to deflect towards oxygen atoms, resulting in local charge imbalance and the formation of strong dipole moments (such as Si-O). - …Ca 2+ This process creates a highly asymmetrical electron cloud distribution on the surface of the self-cleaning glaze, giving it high polarity. The high polarity of the glaze leads to hydrogen bonds or dipole-dipole interactions between water molecules, reducing interfacial energy, making water spread more easily, enhancing the surface wettability of the glaze, and improving its self-cleaning properties.

[0053] Meanwhile, the nano-bovine bone ash in the formulation contains hydroxyapatite. The phosphate ions in hydroxyapatite carry three negative charges, which can strongly attract hydrogen ions (H+) from water molecules. + They also form a hydrogen bond network through electrostatic interactions. Furthermore, the electrostatic interaction between polyvalent phosphate ions and water is stronger than that between ordinary hydroxyl groups and water, making water molecules spread more easily, significantly enhancing the surface wettability of the self-cleaning glaze, and improving the self-cleaning properties of the glaze.

[0054] In addition, the micron / nano-scale grooves in the micro-nano rough structure and the micro-nano porous structure generated during the calcination of calcite can generate capillary forces, which promote the spontaneous penetration of water molecules (i.e., capillary hydrophilic effect), further enhancing the wettability of water molecules and improving self-cleaning properties.

[0055] In summary, this technical solution, through the aforementioned multiple effects, endows the self-cleaning glaze layer with hydrophilic self-cleaning properties, making it relatively easy to remove dirt even when it adheres to the surface. Furthermore, compared to self-cleaning coatings, the self-cleaning glaze layer exhibits significantly improved aging resistance, overcoming the technical deficiency of poor self-cleaning performance caused by the poor aging resistance of existing self-cleaning coatings. Moreover, since the self-cleaning glaze layer is directly fired from the self-cleaning glaze material, its adhesion to antique-style tiles is extremely high, overcoming the technical deficiency of limited adhesion between existing self-cleaning coatings and antique-style tiles, resulting in poor self-cleaning performance. The synergy of these factors contributes to achieving long-lasting and excellent self-cleaning properties for antique-style tiles. In addition, this technical solution eliminates the need for additional self-cleaning coatings on the surface of antique-style tiles, saving production costs and improving production efficiency.

[0056] Finally, since hydrophilic frit is a barren material and prone to sedimentation, this technical solution adds kaolin to the raw materials of the self-cleaning glaze formulation. The suspending effect of kaolin prevents the hydrophilic frit from settling and affecting its performance. Furthermore, the kaolin, quartz, and alumina in the formulation also help improve the hardness and wear resistance of the self-cleaning glaze, ensuring that the self-cleaning glaze is both functional and practical.

[0057] It should be noted that the nano-bovine bone ash in this technical solution cannot be added to the hydrophilic frit. The reason is that the calcination temperature of the hydrophilic frit in the prior art generally exceeds 1500℃. At this high temperature, the hydroxyl calcium phosphate in the nano-bovine bone ash will completely melt and decompose. This will not only significantly reduce the number of hydroxyl groups in the formulation system, but also prevent the hydroxyl calcium phosphate from being used to increase the micro-roughness of the glaze surface due to its complete melting, resulting in a decrease in the self-cleaning property of the self-cleaning glaze layer obtained by calcining the self-cleaning glaze.

[0058] It should be further explained that this technical solution requires the addition of a portion of the calcite in the formulation system to the hydrophilic frit. This is because the hydrophilic frit is a calcined material, while all other raw materials in the self-cleaning glaze, except for the hydrophilic frit, are raw materials. By introducing calcite into the calcined hydrophilic frit, the amount of calcite added to the raw materials can be reduced. This avoids excessive carbon dioxide gas produced during the calcination process of the self-cleaning glaze, which could lead to defects such as pinholes and excessively large pores on the glaze surface, thus ensuring the quality of the glaze surface.

[0059] To further clarify, the particle size of the nano-bovine bone ash is <20nm.

[0060] Nano-sized ox bone ash is rich in hydroxyapatite. When the particle size of nano-sized ox bone ash is limited to <20nm, the specific surface area of ​​nano-sized ox bone ash increases significantly, allowing more hydroxyl groups to be exposed on the surface of the self-cleaning glaze. This increases the number of hydroxyl groups on the surface of the self-cleaning glaze, thereby strengthening the hydrogen bond adsorption capacity between the self-cleaning glaze and water molecules, improving the hydrophilicity of the self-cleaning glaze surface, and making it easier for water to spread on the surface of the self-cleaning glaze and form a uniform water film. This allows water to carry away and remove dirt from the surface of antique bricks, thus improving the self-cleaning effect.

[0061] Meanwhile, when the particle size of the nano-bovine bone ash is limited to <20nm, the nano-bovine bone ash particles can be more evenly distributed in the glaze layer. During the calcination process, it is beneficial to form a more refined and uniform micro-nano rough structure, thereby further enhancing the surface energy and capillary hydrophilic effect, thus enhancing the self-cleaning effect.

[0062] To further clarify, the chemical composition of the nano-bovine bone ash, calculated by mass percentage, includes Ca. 10 (PO4)6(OH)2 60-75%, CaO 15-25%, MgO 5-8%, Na2O 3-5%, and K2O 1-2%.

[0063] This technical solution preferably uses Ca calculated as a mass percentage. 10 Adding nano-bovine bone ash with a (PO4)6(OH)2 (hydroxycalcium hydroxyphosphate) content of 60-75% to the raw materials of self-cleaning glaze is beneficial to increasing the content of hydroxycalcium hydroxyphosphate in the formula system, thereby increasing the number of hydroxyl groups on the surface of the self-cleaning glaze layer obtained by calcination, and thus improving the self-cleaning effect of the self-cleaning glaze layer.

[0064] Furthermore, this technical solution preferably incorporates nano-bovine bone ash with a calcium oxide content of 15-25% (by mass) into the raw materials of the self-cleaning glaze. This increases the calcium oxide content in the formulation system, which not only improves the surface tension of the self-cleaning glaze layer but also increases the amount of calcium feldspar generated in the formulation system, leading to the formation of more micro-nano rough structures and thus enhancing self-cleaning properties. Simultaneously, it also promotes the generation of more non-bridging oxygen and calcium hydroxide in the system, increasing the number of hydroxyl groups on the glaze surface and further enhancing self-cleaning performance. Additionally, the increased calcium oxide content in the formulation system also facilitates the generation of more calcium-non-bridging oxygen dipoles, increasing the polarity of the glaze surface and thus improving self-cleaning properties.

[0065] To further explain, the raw materials include the following by weight: 40-50 parts hydrophilic frit, 4-10 parts kaolin, 18-32 parts quartz, 9-15 parts calcite, 4-10 parts albite, and 2-6 parts nano bovine bone ash.

[0066] The hydrophilic frit, calculated by mass fraction, comprises the following raw materials: 15-19 parts calcite, 15-19 parts wollastonite, 32-52 parts kaolin, 15-19 parts alumina, and 5-11 parts quartz.

[0067] This technical solution optimizes the addition amount of each raw material in the self-cleaning glaze, which helps to ensure the performance of the obtained self-cleaning glaze.

[0068] A method for preparing self-cleaning antique-style tiles, using the aforementioned self-cleaning glaze, includes the following steps:

[0069] A. Calcite, wollastonite, kaolin, aluminum oxide and quartz are mixed evenly, calcined and then water-quenched to obtain a hydrophilic frit;

[0070] B. After mixing the hydrophilic frit, kaolin, quartz, calcite, albite and nano-bovine bone ash evenly, add sodium methyl cellulose, sodium hexametaphosphate and water and ball mill, then sieve to obtain the self-cleaning glaze; wherein, according to the mass percentage, the amount of water added is 33-50% of the dry material of the self-cleaning glaze.

[0071] C. Apply self-cleaning glaze to the surface of the body with a textured surface, dry it, and fire it in a kiln to obtain self-cleaning antique bricks.

[0072] This technical solution also proposes a method for preparing self-cleaning antique-style tiles. The preparation method is simple and easy to operate, ensuring that the obtained self-cleaning antique-style tiles not only have excellent and long-lasting self-cleaning properties, but also help reduce costs. It should be noted that the body in this solution is made by pressing and drying conventional ceramic blanks from the ceramics field; further description of the ceramic blanks is not provided here.

[0073] Specifically, by limiting the amount of water added to 33-50% of the dry material of the self-cleaning glaze, the water content in the self-cleaning glaze is relatively high, which is conducive to the uniform dispersion of nano-ox bone ash in the self-cleaning glaze, thereby helping to ensure the performance of the self-cleaning glaze.

[0074] More specifically, in step B, the amount of sodium carboxymethyl cellulose added is 0.4 to 0.6% of the dry material of the self-cleaning glaze, and the amount of sodium hexametaphosphate added is 0.4 to 0.8% of the dry material of the self-cleaning glaze. After adding the above additives to the mixture, the mixture is ball-milled for 12 hours and then sieved to obtain the self-cleaning glaze.

[0075] Furthermore, this technical solution introduces sodium hexametaphosphate as a key additive. The six phosphate groups in the sodium hexametaphosphate molecule can preferentially react with polyvalent metal ions (such as Ca) in the formulation. 2+ It forms a highly stable chelate structure, which blocks ion bridging through steric hindrance, thereby inhibiting component aggregation and flocculation. At the same time, sodium hexametaphosphate, with its polyphosphate chain structure, exhibits stronger steric hindrance dispersion ability compared to sodium tripolyphosphate. It can uniformly disperse the raw materials in the glaze, avoid glaze defects caused by agglomeration, and ensure that the glaze system maintains homogeneity and rheological stability during high-temperature calcination, ultimately improving the density and self-cleaning performance of the self-cleaning glaze layer.

[0076] To further explain, in step A, the calcination temperature curve of the hydrophilic frit is as follows: the temperature is increased from room temperature to 1530°C at a heating rate of 8-10°C / min, and then held for 35-45 minutes.

[0077] This technical solution optimizes the calcination temperature curve of the hydrophilic frit, enabling all raw materials in the hydrophilic frit formulation to melt. This not only helps ensure the performance of the hydrophilic frit but also gives the self-cleaning glaze with added hydrophilic frit a certain degree of transparency after calcination, thus improving its permeability.

[0078] To further explain, in step B, the specific gravity of the self-cleaning glaze is 1.15 to 1.2, and calculated by mass percentage, the residue of the self-cleaning glaze after passing through a 325-mesh sieve is 0.2 to 0.4%.

[0079] When the specific gravity of the self-cleaning glaze is too high, the glaze becomes too thick, resulting in poor fluidity and uneven application, easily leading to defects such as glaze streaks. Furthermore, an excessively high specific gravity can also obstruct the escape of gases and moisture generated during firing, causing the glaze layer to crack easily. Conversely, if the specific gravity is too low, the glaze becomes too fluid, easily flowing during application, also resulting in uneven application and glaze streaks. Additionally, an excessively low specific gravity leads to excessive moisture in the glaze, making it prone to cracking during firing. Therefore, this technical solution limits the specific gravity of the self-cleaning glaze to 1.15–1.2, which helps ensure the uniformity of the self-cleaning effect and the quality of the glaze surface in the resulting antique-style tiles.

[0080] Furthermore, this technical solution limits the fineness of the self-cleaning glaze, ensuring that the raw materials in the self-cleaning glaze are evenly dispersed, thereby guaranteeing the performance of the product.

[0081] To further explain, in step C, the thickness of the self-cleaning glaze is 0.05 to 0.1 mm.

[0082] If the self-cleaning glaze is applied too thinly, it can easily lead to glaze defects such as missed areas in the body, affecting not only the uniformity of self-cleaning properties but also the product's appearance. Conversely, if the glaze is applied too thickly, the high moisture content in the glaze can cause a sudden increase in internal steam pressure during rapid drying, potentially breaking the bond strength between the body and glaze, leading to cracking of the body or peeling of the glaze. Furthermore, the nano-bone ash particles are prone to micro-cracks due to stress concentration during drying shrinkage, further weakening the glaze's density and self-cleaning function. Therefore, this technical solution limits the glaze thickness to 0.05–0.1 mm to ensure a uniform moisture gradient and stress distribution in the self-cleaning glaze layer during drying and firing, guaranteeing the glaze quality and uniformity of the self-cleaning effect in the antique-style bricks.

[0083] To further explain, in step C, the firing temperature curve of the self-cleaning antique brick includes a preheating section, a preheating section, a high-temperature section, a heat preservation section, a transition section, a rapid cooling section, a slow cooling section, a strong cooling section, and a final cooling section.

[0084] The preheating section takes 3 to 6 minutes to raise the temperature from room temperature to 750°C.

[0085] The temperature rises from 750°C to 1050°C in the initial temperature range, taking 1.2 to 4 minutes.

[0086] The high-temperature section rises from 1050℃ to 1145℃ in 5–8 minutes;

[0087] The insulation section is maintained at 1145℃ for 4.5–10 minutes.

[0088] The transition section cools the temperature from 1145℃ to 950℃ in 1.8–5 minutes.

[0089] The rapid cooling section reduces the temperature from 950°C to 630°C in 2–3 minutes.

[0090] The slow cooling section reduces the temperature from 630°C to 610°C in 5–10 minutes.

[0091] The rapid cooling section reduces the temperature from 610°C to 210°C in 3.5–6 minutes.

[0092] The final cooling section cools the temperature from 310°C to 200°C in 4–8 minutes.

[0093] This technical solution incorporates a rapid cooling section, which quickly freezes the high-temperature liquid phase structure, retaining more non-bridging oxygen and promoting the reaction between non-bridging oxygen and water molecules to generate more hydroxyl groups. Simultaneously, rapid cooling can inhibit the dehydration reaction of hydroxyl groups in calcium hydroxyphosphate, preventing hydroxyl group loss. This dual mechanism synergistically enhances the surface hydroxyl content.

[0094] Furthermore, the calcination cycle of this technical solution is 30–60 minutes, which belongs to the rapid firing mechanism. Rapid firing can suppress the excessive growth of crystals such as anorthite during the decomposition of calcite, preserving the micro-nano porous structure produced by calcination. The rapid cooling section further solidifies this micro-nano porous structure, making it uniformly distributed in the glaze layer. The aforementioned micro-nano porous structure serves as a moisture adsorption site, promoting the hydrogen bonding between non-bridging oxygen and adsorbed water in the glaze layer and subsequent dissociation reactions, generating more surface hydroxyl groups to enhance the hydrophilicity and self-cleaning properties of the self-cleaning glaze layer.

[0095] A self-cleaning antique brick is prepared using the above-mentioned method for preparing self-cleaning antique bricks. The static contact angle of the self-cleaning antique brick without being soaked in boiling water is 5-9°, and the static contact angle after being soaked in boiling water for 30 days is 12-16°.

[0096] A self-cleaning antique brick prepared by the above-mentioned method has a static contact angle of 5-9° when not soaked in boiling water, and a static contact angle of 12-16° after being soaked in boiling water for 30 days, exhibiting excellent and long-lasting self-cleaning properties.

[0097] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0098] Performance testing:

[0099] Static contact angle before soaking: The static contact angle of the self-cleaning antique brick before soaking in boiling water is tested according to the test method of "GB / T 30447-2013 Nanofilm Contact Angle Measurement Method". If the static contact angle is ≤9°, it is qualified.

[0100] Static contact angle after soaking: The static contact angle of self-cleaning antique bricks after soaking in boiling water for 30 days is tested according to the test method of "GB / T 30447-2013 Method for Measurement of Contact Angle of Nanofilm". If the static contact angle is ≤16°, it is qualified.

[0101] Anti-slip performance: Anti-slip performance was tested according to DIN 51130:2014 Anti-slip Standard.

[0102] Mohs hardness: The Mohs hardness of self-cleaning antique tiles is tested using a Mohs hardness tester.

[0103] Example 1

[0104] A. According to the mass fractions, 16 parts of calcite, 18 parts of wollastonite, 42 parts of kaolin, 17 parts of alumina and 7 parts of quartz are mixed evenly, calcined and then water-quenched to obtain a hydrophilic frit; wherein, the calcination temperature curve of the hydrophilic frit is: from room temperature to 1530℃ at a heating rate of 8℃ / min, and then held for 40min.

[0105] B. According to the mass percentage, 45 parts of hydrophilic frit, 6 parts of kaolin, 25 parts of quartz, 12 parts of calcite, 7 parts of albite, and 4 parts of nano-ox bone ash are mixed evenly. Sodium methylcellulose, sodium hexametaphosphate, and water are then added and ball-milled. The mixture is then sieved to obtain a self-cleaning glaze. The nano-ox bone ash has a particle size of 15 nm. The chemical composition of the nano-ox bone ash, calculated by mass percentage, includes Ca... 10 The self-cleaning glaze contains 70% (PO4)6(OH)2, 17% CaO, 8% MgO, 3% Na2O, and 2% K2O. The specific gravity of the self-cleaning glaze is 1.15, and the residue after passing through a 325-mesh sieve is 0.3% by mass percentage. The amount of sodium carboxymethyl cellulose added is 0.5% of the dry self-cleaning glaze, the amount of sodium hexametaphosphate added is 0.6% of the dry self-cleaning glaze, and the amount of water added is 40% of the dry self-cleaning glaze.

[0106] C. Apply self-cleaning glaze to the surface of the textured body, dry it, and fire it in a kiln to obtain self-cleaning antique bricks; the glaze thickness is 0.05mm; the firing temperature curve of the self-cleaning antique bricks includes a preheating section, a preheating section, a high-temperature section, a holding section, a transition section, a rapid cooling section, a slow cooling section, a strong cooling section, and a final cooling section; the preheating section takes 4 minutes to raise the temperature from room temperature to 750℃; the preheating section takes 2 minutes to raise the temperature from 750℃ to 1050℃; the high-temperature section... The temperature rises from 1050℃ to 1145℃ in 6 minutes; the heat preservation section is at 1145℃ for 5 minutes; the transition section cools from 1145℃ to 950℃ in 3 minutes; the rapid cooling section cools from 950℃ to 630℃ in 2 minutes; the slow cooling section cools from 630℃ to 610℃ in 6 minutes; the strong cooling section cools from 610℃ to 210℃ in 4 minutes; and the final cooling section cools from 310℃ to 200℃ in 5 minutes.

[0107] Example 2

[0108] A. According to the mass fractions, 18 parts of calcite, 15 parts of wollastonite, 39 parts of kaolin, 18 parts of alumina and 10 parts of quartz are mixed evenly, calcined and then water-quenched to obtain a hydrophilic frit; wherein, the calcination temperature curve of the hydrophilic frit is: from room temperature to 1530℃ at a heating rate of 10℃ / min, and then held at that temperature for 35min;

[0109] B. According to the mass percentage, 40 parts of hydrophilic frit, 10 parts of kaolin, 30 parts of quartz, 10 parts of calcite, 8 parts of albite, and 2 parts of nano-ox bone ash are mixed evenly. Sodium methylcellulose, sodium hexametaphosphate, and water are then added and ball-milled. The mixture is then sieved to obtain a self-cleaning glaze. The nano-ox bone ash has a particle size of 18 nm. The chemical composition of the nano-ox bone ash, calculated by mass percentage, includes Ca... 10 The self-cleaning glaze contains 70% (PO4)6(OH)2, 17% CaO, 8% MgO, 3% Na2O, and 2% K2O. The specific gravity of the self-cleaning glaze is 1.2, and the residue after passing through a 325-mesh sieve is 0.2% by mass percentage. The amount of sodium carboxymethyl cellulose added is 0.6% of the dry self-cleaning glaze, the amount of sodium hexametaphosphate added is 0.4% of the dry self-cleaning glaze, and the amount of water added is 33% of the dry self-cleaning glaze.

[0110] C. Apply self-cleaning glaze to the surface of the textured body, dry it, and fire it in a kiln to obtain self-cleaning antique bricks; the glaze thickness is 0.1mm; the firing temperature curve of the self-cleaning antique bricks includes a preheating section, a preheating section, a high-temperature section, a holding section, a transition section, a rapid cooling section, a slow cooling section, a strong cooling section, and a final cooling section; the preheating section raises the temperature from room temperature to 750℃ in 3 minutes; the preheating section raises the temperature from 750℃ to 1050℃ in 3 minutes; the high-temperature section... The process takes 4 minutes to raise the temperature from 1050℃ to 1145℃; 8 minutes to maintain the temperature at 1145℃ in the heat preservation stage; 2 minutes to lower the temperature from 1145℃ to 950℃ in the transition stage; 3 minutes to lower the temperature from 950℃ to 630℃ in the rapid cooling stage; 10 minutes to lower the temperature from 630℃ to 610℃ in the slow cooling stage; 6 minutes to lower the temperature from 610℃ to 210℃ in the strong cooling stage; and 4 minutes to lower the temperature from 310℃ to 200℃ in the final cooling stage.

[0111] Example 3

[0112] A. According to the mass fractions, 19 parts of calcite, 18 parts of wollastonite, 40 parts of kaolin, 15 parts of alumina and 8 parts of quartz are mixed evenly, calcined and then water-quenched to obtain a hydrophilic frit; wherein, the calcination temperature curve of the hydrophilic frit is: from room temperature to 1530℃ at a heating rate of 9℃ / min, and then held at that temperature for 45min.

[0113] B. According to the mass percentage, 50 parts of hydrophilic frit, 6 parts of kaolin, 18 parts of quartz, 15 parts of calcite, 7 parts of albite, and 4 parts of nano-ox bone ash are mixed evenly. Sodium methylcellulose, sodium hexametaphosphate, and water are then added and ball-milled. The mixture is then sieved to obtain a self-cleaning glaze. The particle size of the nano-ox bone ash is 13 nm. The chemical composition of the nano-ox bone ash, calculated by mass percentage, includes Ca... 10 The self-cleaning glaze contains 70% (PO4)6(OH)2, 17% CaO, 8% MgO, 3% Na2O, and 2% K2O. The specific gravity of the self-cleaning glaze is 1.2, and the residue after passing through a 325-mesh sieve is 0.4% by mass percentage. The amount of sodium carboxymethyl cellulose added is 0.4% of the dry self-cleaning glaze, the amount of sodium hexametaphosphate added is 0.8% of the dry self-cleaning glaze, and the amount of water added is 50% of the dry self-cleaning glaze.

[0114] C. Apply self-cleaning glaze to the surface of the textured body, dry it, and fire it in a kiln to obtain self-cleaning antique bricks; the glaze thickness is 0.08mm; the firing temperature curve of the self-cleaning antique bricks includes a preheating section, a preheating section, a high-temperature section, a holding section, a transition section, a rapid cooling section, a slow cooling section, a strong cooling section, and a final cooling section; the preheating section takes 6 minutes to raise the temperature from room temperature to 750℃; the preheating section takes 3 minutes to raise the temperature from 750℃ to 1050℃; the high-temperature section... The temperature rises from 1050℃ to 1145℃ in 7 minutes; the holding period is at 1145℃ for 8 minutes; the transition period cools from 1145℃ to 950℃ in 4 minutes; the rapid cooling period cools from 950℃ to 630℃ in 2.5 minutes; the slow cooling period cools from 630℃ to 610℃ in 7 minutes; the strong cooling period cools from 610℃ to 210℃ in 5 minutes; and the final cooling period cools from 310℃ to 200℃ in 6 minutes.

[0115] Comparative Example 1

[0116] The self-cleaning antique brick in Comparative Example 1 includes an antique brick substrate and a hydrophilic self-cleaning coating distributed from bottom to top; the hydrophilic self-cleaning coating is obtained by curing a super-hydrophilic coating of model SM-TM-QS3500 / 3200 from Shangmeng Technology Wuxi Co., Ltd.

[0117] Comparative Example 2

[0118] The preparation method and raw materials of Comparative Example 2 are the same as those of Example 1, except that the self-cleaning glaze of Comparative Example 2 does not contain nano-bovine bone ash.

[0119] Comparative Example 3

[0120] The preparation method and raw materials of Comparative Example 3 are the same as those of Example 1, except that calcite was not added to either the self-cleaning glaze or the hydrophilic frit of Comparative Example 3.

[0121] The performance of the self-cleaning antique-style tiles prepared in the examples and comparative examples was tested, and the results are shown in Table 1 below:

[0122] Table 1. Performance test results of different self-cleaning antique bricks in the examples and comparative examples.

[0123]

[0124] As shown in Table 1, the static contact angle of the antique bricks obtained by this technical solution is 5-9° when they are not soaked in boiling water, and 12-16° when they are soaked in boiling water for 30 days. They not only have excellent and long-lasting self-cleaning properties, but also good anti-slip properties and hardness. They combine functionality and practicality, and are more conducive to meeting the needs of consumers.

[0125] In Comparative Example 1, a self-cleaning antique brick was obtained by applying a self-cleaning coating to the surface of the antique brick substrate. Although the obtained antique brick had a small static contact angle with water before soaking and had good self-cleaning properties, the self-cleaning coating in Comparative Example 1 peeled off after soaking due to the poor aging resistance of the self-cleaning coating and its limited adhesion to the brick surface. The self-cleaning durability was poor, and the static contact angle after soaking could not be measured.

[0126] In Comparative Example 2, the absence of nano-bovine bone ash prevented the use of nano-bovine bone ash to enhance self-cleaning properties, thus reducing the self-cleaning performance of the antique-style bricks.

[0127] In Comparative Example 3, the absence of calcite reduced the amount of calcium oxide generated during glaze firing. This not only decreased the amount of anorthite generated, leading to a reduction in the micro-nano rough structure of the glaze surface, but also prevented the formation of micro-nano porous structures from the carbon dioxide gas produced by the inability to decompose calcite, thus affecting the number of micro-nano porous structures and impacting self-cleaning properties. Simultaneously, the reduced calcium oxide generation weakened its effect on enhancing the surface tension of the glaze layer, affecting self-cleaning performance. Furthermore, it prevented the use of calcium oxide generated from calcite decomposition to increase the number of hydroxyl groups on the glaze surface through various pathways (such as hydrolysis and promoting the formation of non-bridging oxygen), also affecting self-cleaning performance. Moreover, it also prevented the use of calcium oxide generated from calcite decomposition to increase the polarity of the glaze surface by forming calcium-non-bridging oxygen dipoles, further affecting self-cleaning performance.

[0128] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A self-cleaning glaze, characterized in that, The raw materials include the following components by weight: 40-50 parts hydrophilic frit, 4-10 parts kaolin, 18-32 parts quartz, 9-15 parts calcite, 4-10 parts albite, and 2-6 parts nano bovine bone ash. The hydrophilic frit, calculated by mass fraction, comprises the following raw materials: 15-19 parts calcite, 15-19 parts wollastonite, 32-52 parts kaolin, 15-19 parts alumina, and 5-11 parts quartz.

2. The self-cleaning glaze according to claim 1, characterized in that, The particle size of the nano-bovine bone ash is <20nm.

3. The self-cleaning glaze according to claim 1, characterized in that, The chemical composition of the nano-bovine bone ash, calculated as a percentage by weight, includes Ca. 10 (PO4)6(OH)2 60-75%, CaO 15-25%, MgO 5-8%, Na2O 3-5% and K2O 1-2%.

4. A method for preparing self-cleaning antique-style bricks, characterized in that, Using the self-cleaning glaze as described in any one of claims 1 to 3 includes the following steps: A. Calcite, wollastonite, kaolin, aluminum oxide and quartz are mixed evenly, calcined and then water-quenched to obtain a hydrophilic frit; B. After mixing the hydrophilic frit, kaolin, quartz, calcite, albite and nano-bovine bone ash evenly, add sodium methyl cellulose, sodium hexametaphosphate and water and ball mill, then sieve to obtain the self-cleaning glaze; wherein, according to the mass percentage, the amount of water added is 33-50% of the dry material of the self-cleaning glaze. C. Apply self-cleaning glaze to the surface of the body with a textured surface, dry it, and fire it in a kiln to obtain self-cleaning antique bricks.

5. The method for preparing a self-cleaning antique-style brick according to claim 4, characterized in that, In step A, the calcination temperature curve of the hydrophilic frit is as follows: the temperature is increased from room temperature to 1530℃ at a heating rate of 8-10℃ / min, and then held for 35-45min.

6. The method for preparing a self-cleaning antique-style brick according to claim 4, characterized in that, In step B, the specific gravity of the self-cleaning glaze is 1.15 to 1.2, and the residue of the self-cleaning glaze after passing through a 325-mesh sieve is 0.2 to 0.4% by mass percentage.

7. The method for preparing a self-cleaning antique-style brick according to claim 4, characterized in that, In step C, the thickness of the self-cleaning glaze is 0.05 to 0.1 mm.

8. The method for preparing a self-cleaning antique-style brick according to claim 4, characterized in that, In step C, the firing temperature curve of the self-cleaning antique brick includes a preheating section, a preheating section, a high-temperature section, a heat preservation section, a transition section, a rapid cooling section, a slow cooling section, a strong cooling section, and a final cooling section. The preheating section takes 3 to 6 minutes to raise the temperature from room temperature to 750°C. The temperature rises from 750°C to 1050°C in the initial temperature range, taking 1.2 to 4 minutes. The high-temperature section rises from 1050℃ to 1145℃ in 5–8 minutes; The insulation section is maintained at 1145℃ for 4.5–10 minutes. The transition section cools the temperature from 1145℃ to 950℃ in 1.8–5 minutes. The rapid cooling section reduces the temperature from 950°C to 630°C in 2–3 minutes. The slow cooling section reduces the temperature from 630°C to 610°C in 5–10 minutes. The rapid cooling section reduces the temperature from 610°C to 210°C in 3.5–6 minutes. The final cooling section cools the temperature from 310°C to 200°C in 4–8 minutes.

9. A self-cleaning antique-style brick, characterized in that: The self-cleaning antique brick is prepared using the preparation method of any one of claims 4 to 8. The static contact angle of the self-cleaning antique brick without soaking in boiling water is 5 to 9°, and the static contact angle after soaking in boiling water for 30 days is 12 to 16°.

Images