Overglaze for sanitary ceramic, sanitary ceramic and preparation method of sanitary ceramic

Abstract

The invention relates to the field of sanitary ceramics, in particular to a cover glaze for sanitary ceramics, the sanitary ceramics and a preparation method of the cover glaze, and the cover glaze is prepared from the following raw materials in parts by mass: 18-25 parts of potassium feldspar, 20-28 parts of albite, 18-25 parts of quartz powder, 4-7 parts of calcite, 2-4 parts of kaolin, 2-5 parts of dolomite, 8-12 parts of zirconium silicate, 1-3 parts of barium carbonate and 2-5 parts of burnt talcum powder, and the raw materials do not contain zinc oxide. The cover glaze for sanitary ceramics provided by the invention is favorable for ensuring high hardness, high wear resistance, excellent stain resistance, high glossiness and high whiteness on the premise of reducing the raw material cost, reducing the cracking risk and widening the firing temperature range, and overcomes the defects in the prior art.

Description

Technical Field

[0001] This invention relates to the field of sanitary ceramics, and more particularly to a glaze for sanitary ceramics, sanitary ceramics, and a method for preparing the same. Background Technology

[0002] Today, sanitary ceramics (such as sinks, bathtubs, and toilets) are important decorative materials in everyday homes. With their high strength, high density, good stain resistance, and chemical stability, they are favored by consumers and widely used in residential kitchens and bathrooms, public buildings, and commercial spaces.

[0003] In sanitary ceramics manufacturing, the glaze, as a vitreous surface layer covering the body, directly determines the product's appearance, texture, and performance. Zinc oxide, due to its high purity, strong fluxing properties, and excellent chemical stability, has long been widely added to glaze formulations as a key flux, typically at a dosage of 5-15%. However, zinc oxide is significantly more expensive than commonly used mineral raw materials in ceramics, resulting in a persistently high overall raw material cost for the glaze. Furthermore, while zinc oxide promotes microcrystal precipitation and provides an opaque effect, it can also inhibit the glaze's gloss to some extent.

[0004] To reduce the cost of glazes and improve their gloss, the industry has attempted to replace zinc oxide entirely or partially by increasing the proportion of low-cost natural fluxes such as potassium feldspar and sodium feldspar. These techniques introduce a large amount of potassium and sodium ions as powerful network modifiers, significantly disrupting the silica-oxygen network of the glaze melt, drastically reducing high-temperature viscosity, thereby enhancing melt fluidity and spreadability, ultimately forming a smoother and denser surface with higher gloss. However, these techniques have the following drawbacks: First, the adaptability of the body and glaze deteriorates: the thermal expansion behavior of potassium feldspar and sodium feldspar differs from that of zinc oxide, and the content of their natural components (especially K2O, Na2O content and iron and titanium impurities) fluctuates, which can easily lead to an unstable coefficient of expansion of the glaze, increase the risk of thermal expansion mismatch with the body, reduce thermal shock resistance, cause glaze cracking, and reduce hardness, wear resistance and stain resistance.

[0005] Secondly, the firing temperature range narrows: Zinc oxide, as a strong flux, can effectively broaden the firing temperature range of glazes and improve the tolerance of the firing process. In contrast, potassium feldspar and sodium feldspar have weaker fluxing abilities and are significantly affected by mineral composition. Increasing their dosage makes the melting behavior of the glaze more sensitive to the kiln temperature profile (such as heating rate and high-temperature holding time), resulting in a narrower firing temperature range, increased difficulty in firing control, and reduced process stability.

[0006] Third, reduced glaze whiteness: Zinc oxide itself helps to improve glaze whiteness. When a large amount of natural feldspar is used, the total amount of coloring impurities such as trace iron and titanium it contains increases, which may cause the glaze to show a yellowish or grayish tendency, making it difficult to meet the quality requirements of high-end sanitary ceramics.

[0007] In conclusion, existing technologies cannot simultaneously achieve high hardness, high wear resistance, excellent stain resistance, high gloss, and high whiteness to meet application requirements while reducing raw material costs, minimizing cracking risks, and widening the firing temperature range. Summary of the Invention

[0008] The purpose of this invention is to provide a surface glaze for sanitary ceramics that, while reducing raw material costs, minimizing the risk of cracking, and broadening the firing temperature range, ensures high hardness, high wear resistance, excellent stain resistance, high gloss, and high whiteness, overcoming the shortcomings of existing technologies.

[0009] The second objective of this invention is to provide a method for preparing sanitary ceramics. The method is simple and easy to operate, and it is beneficial to ensure high hardness, high wear resistance, excellent stain resistance, high gloss and high whiteness while reducing raw material costs, reducing the risk of cracking and widening the firing temperature range.

[0010] The third objective of this invention is to provide a sanitary ceramic prepared by the above-mentioned method, which has a Mohs hardness ≥5, a wear resistance of at least grade B, a stain resistance of grade 5, a gloss ≥90°, and a whiteness ≥90°, which helps to ensure that the obtained sanitary ceramic has high hardness, high wear resistance, excellent stain resistance, high gloss, and high whiteness.

[0011] To achieve this objective, the present invention adopts the following technical solution: A glaze for sanitary ceramics comprises, by weight parts, the following raw materials: 18-25 parts potassium feldspar, 20-28 parts sodium feldspar, 18-25 parts quartz powder, 4-7 parts calcite, 2-4 parts kaolin, 2-5 parts dolomite, 8-12 parts zirconium silicate, 1-3 parts barium carbonate, and 2-5 parts calcined talc powder, wherein the raw materials do not contain zinc oxide; The whiteness of the potassium feldspar is ≥50°, and the chemical composition of the potassium feldspar includes K2O, TiO2 and Fe2O3. Calculated by mass percentage, the K2O content in the potassium feldspar is ≥10%, and the sum of the contents of TiO2 and Fe2O3 is <0.3%. The whiteness of the albite is ≥45°, and the chemical composition of the albite includes K2O, TiO2 and Fe2O3. Calculated by mass percentage, the Na2O content in the albite is ≥9%, and the sum of the contents of TiO2 and Fe2O3 is <0.3%.

[0012] Further, calculated by mass percentage, the chemical composition of the potassium feldspar includes 0.1–0.15% MgO, 0.3–0.4% CaO, 12.1–12.3% Al2O3, 65.4–66.6% SiO2, 10–11% K2O, 0.5–0.6% Na2O, 0.12–0.15% TiO2, and 0.08–0.12% Fe2O3, with the remainder being loss on ignition.

[0013] Further, calculated by mass percentage, the albite comprises 0.15–0.2% MgO, 0.05–0.1% CaO, 17.1–17.3% Al2O3, 67.2–67.4% SiO2, 1.3–1.4% K2O, 9–10% Na2O, 0.05–0.1% TiO2, and 0.05–0.1% Fe2O3, with the remainder being loss on ignition.

[0014] Furthermore, calculated by mass percentage, the potassium feldspar and the sodium feldspar, when passed through a 200-mesh sieve, both have a residue of ≤8%.

[0015] Furthermore, the raw materials also include frit; calculated by mass parts, the surface glaze for sanitary ceramics includes the following raw materials: 18-25 parts potassium feldspar, 20-28 parts sodium feldspar, 18-25 parts quartz powder, 4-7 parts calcite, 2-4 parts kaolin, 2-5 parts dolomite, 8-12 parts zirconium silicate, 1-3 parts barium carbonate, 2-5 parts calcined talc powder, and 2-6 parts frit; The chemical composition of the fused block, calculated by mass percentage, includes 60-63% SiO2, 8-10% Al2O3, 0.05-0.10% Fe2O3, 0.01-0.05% TiO2, 8-12% CaO, 1-2% MgO, 3-4% K2O, 1-1.5% Na2O, and 3-6% ZnO, with the remainder being loss on ignition.

[0016] A method for preparing sanitary ceramics, using the sanitary ceramic glaze as described above, includes the following steps: A. After mixing potassium feldspar, sodium feldspar, quartz powder, calcite, kaolin, dolomite, zirconium silicate, barium carbonate, calcined talc powder and frit evenly according to the formula, add sodium carboxymethyl cellulose, sodium tripolyphosphate and water and ball mill to obtain the basic glaze slurry; after the basic glaze slurry is subjected to primary sieving and secondary sieving, the surface glaze for sanitary ceramics is obtained. B. Apply a glaze to the surface of the sanitary ceramic body to form a glaze layer; wherein the coefficient of thermal expansion of the body is (215~240)×10. -6 / ℃; C. After drying, the product is calcined in a kiln to obtain sanitary ceramics; wherein the calcination temperature is 1200-1230℃.

[0017] Further, in step A, the initial sieving specifically involves filtering the basic glaze slurry sequentially through a 120-mesh sieve and a 180-mesh sieve to obtain a coarse glaze slurry. The secondary sieving specifically involves adding sodium carboxymethyl cellulose to the coarse sieving glaze and mixing it evenly, then filtering it sequentially through a 200-mesh sieve and a 120-mesh sieve to obtain the surface glaze for sanitary ceramics; wherein, calculated by mass percentage, the amount of sodium carboxymethyl cellulose added is 0.1 to 0.2% of the dry material added to the surface glaze for sanitary ceramics.

[0018] Further, in step A, the specific gravity of the glaze used in sanitary ceramics is 1.75 to 1.85, and the fineness of the glaze used in sanitary ceramics is through a 325-mesh sieve, with a residue of 0.1 to 0.2% by mass percentage.

[0019] Furthermore, in step B, the glaze thickness of the sanitary ceramic surface glaze is 0.7–0.9 mm.

[0020] A sanitary ceramic, prepared using the sanitary ceramic preparation method described above, wherein the sanitary ceramic has a Mohs hardness ≥5, abrasion resistance at least grade B, stain resistance grade 5, gloss ≥90°, and whiteness ≥90°.

[0021] The technical solution provided by this invention may include the following beneficial effects: 1. Potassium feldspar, sodium feldspar, calcite, barium carbonate, and calcined talc powder are used to introduce potassium oxide, sodium oxide, calcium oxide, barium oxide, and magnesium oxide, respectively. Dolomite [CaMg(CO3)2] can introduce magnesium oxide and calcium oxide into the formulation system. Therefore, in this technical solution, the combined action of these raw materials—potassium feldspar, sodium feldspar, calcite, barium carbonate, calcined talc powder, and dolomite—generates a low-melting-point K2O-Na2O-MgO-CaO-BaO multi-component composite flux. This multi-component composite flux allows the glaze to form a liquid phase earlier at a lower temperature. Due to the viscous flow and surface tension of the liquid phase, it can fill the voids inside the glaze melt formed during glaze firing in advance, promoting particle rearrangement, bringing them closer together, and bonding them into a whole. In addition, the alkaline oxides gradually enter the liquid phase, which gradually increases the amount of liquid phase generated under the action of multi-component flux. It gradually appears in the surface glaze melt in a stepwise manner and gradually dissolves other substances, causing the surface glaze layer formed after the surface glaze melt cools to become dense. This makes the flux in the formula mainly potassium feldspar and sodium feldspar, which can also achieve the purpose of reducing the firing temperature and widening the firing temperature range.

[0022] 2. The surface glaze formulation of this technical solution abandons the design that relies entirely on large amounts of potassium feldspar and sodium feldspar. Instead, it constructs a K2O-Na2O-MgO-CaO-BaO multi-component composite flux system composed of potassium feldspar, sodium feldspar, calcite, barium carbonate, calcined talc powder, and dolomite. In the above multi-component composite flux system, K2O and Na2O can significantly increase the coefficient of thermal expansion, while CaO, MgO, and BaO (especially MgO) are beneficial for reducing the coefficient of thermal expansion. At the same time, quartz powder in the formulation raw materials can increase the coefficient of thermal expansion, while kaolin and zirconium silicate can reduce the coefficient of thermal expansion. By limiting the amount of each of the above raw materials added to the formulation, the final coefficient of thermal expansion of the surface glaze reaches (215~240) × 10⁻⁶, which is the same as the coefficient of thermal expansion of the existing body. -6 / ℃ is within the range that matches.

[0023] 3. This technical solution ensures that the whiteness of potassium feldspar is ≥50° and that of sodium feldspar is ≥45° by limiting the whiteness of the base flux raw materials to a sufficiently high intrinsic whiteness, laying the physical foundation for obtaining a high-whiteness glaze. Meanwhile, iron and titanium ions are the main factors causing yellowing and graying of the glaze. This technical solution limits the sum of TiO2 and Fe2O3 content in both potassium feldspar and sodium feldspar to less than 0.3%, fundamentally suppressing glaze color deviation from the mineral raw material level, which is beneficial for achieving high whiteness. Furthermore, the zirconium silicate introduced into the formula acts as a highly efficient opacifier; through its refraction and scattering effects in the glaze melt, it helps to improve the hiding power and overall whiteness of the glaze layer. Detailed Implementation

[0024] This technical solution provides a glaze for sanitary ceramics, which, by weight, includes the following raw materials: 18-25 parts potassium feldspar, 20-28 parts sodium feldspar, 18-25 parts quartz powder, 4-7 parts calcite, 2-4 parts kaolin, 2-5 parts dolomite, 8-12 parts zirconium silicate, 1-3 parts barium carbonate, and 2-5 parts calcined talc powder, and the raw materials do not contain zinc oxide; The whiteness of the potassium feldspar is ≥50°, and the chemical composition of the potassium feldspar includes K2O, TiO2 and Fe2O3. Calculated by mass percentage, the K2O content in the potassium feldspar is ≥10%, and the sum of the contents of TiO2 and Fe2O3 is <0.3%. The whiteness of the albite is ≥45°, and the chemical composition of the albite includes K2O, TiO2 and Fe2O3. Calculated by mass percentage, the Na2O content in the albite is ≥9%, and the sum of the contents of TiO2 and Fe2O3 is <0.3%.

[0025] To address the technical challenge of simultaneously achieving high hardness, high wear resistance, excellent stain resistance, high gloss, and high whiteness in existing technologies while reducing raw material costs, minimizing cracking risks, and broadening the firing temperature range, this technical solution proposes a surface glaze for sanitary ceramics. By designing the formula and proportions of raw materials and strictly selecting key ingredients, this approach helps to ensure high hardness, high wear resistance, excellent stain resistance, high gloss, and high whiteness while reducing raw material costs, minimizing cracking risks, and broadening the firing temperature range.

[0026] Specifically, the raw materials for the glaze used in sanitary ceramics include potassium feldspar, sodium feldspar, quartz powder, calcite, kaolin, dolomite, zirconium silicate, barium carbonate, and calcined talc. Potassium feldspar, sodium feldspar, calcite, barium carbonate, and calcined talc introduce potassium oxide, sodium oxide, calcium oxide, barium oxide, and magnesium oxide, respectively. Dolomite [CaMg(CO3)2] introduces magnesium oxide and calcium oxide into the formulation system. Therefore, in this technical solution, the combined action of these raw materials—potassium feldspar, sodium feldspar, calcite, barium carbonate, calcined talc, and dolomite—generates a eutectic K2O-Na2O-MgO-CaO-BaO multi-component composite flux. This multi-component composite flux allows the glaze to form a liquid phase earlier at a lower temperature. Due to the viscous flow and surface tension of the liquid phase, it can fill the voids inside the glaze melt formed during calcination, promoting particle rearrangement, bringing particles closer together, and bonding them into a cohesive whole. In addition, the alkaline oxides gradually enter the liquid phase, which gradually increases the amount of liquid phase generated under the action of multi-component flux. It gradually appears in the surface glaze melt in a stepwise manner and gradually dissolves other substances, causing the surface glaze layer formed after the surface glaze melt cools to become dense. This makes the flux in the formula mainly potassium feldspar and sodium feldspar, which can also achieve the purpose of reducing the firing temperature and widening the firing temperature range.

[0027] Secondly, the surface glaze formulation of this technical solution abandons the design that relies entirely on large amounts of potassium feldspar and sodium feldspar. Instead, it constructs a K2O-Na2O-MgO-CaO-BaO multi-component composite flux system composed of potassium feldspar, sodium feldspar, calcite, barium carbonate, calcined talc powder, and dolomite. In the above multi-component composite flux system, K2O and Na2O can significantly increase the coefficient of thermal expansion, while CaO, MgO, and BaO (especially MgO) are beneficial for reducing the coefficient of thermal expansion. At the same time, quartz powder in the formulation raw materials can increase the coefficient of thermal expansion, while kaolin and zirconium silicate can reduce the coefficient of thermal expansion. By limiting the amount of each of the above raw materials added to the formulation, the final coefficient of thermal expansion of the surface glaze reaches (215~240) × 10⁻⁶, which is the same as the coefficient of thermal expansion of the existing body. -6 / ℃ is within the range that matches.

[0028] In addition, this technical solution limits the content of strong coloring oxides (TiO2 and Fe2O3) in potassium feldspar and sodium feldspar, the content of potassium oxide in potassium feldspar, and the content of sodium oxide in sodium feldspar. This directly reduces impurity variables that interfere with the high-temperature performance and thermal expansion behavior of the glaze. It ensures the stability of the glaze expansion coefficient between different production batches from the raw material end, fundamentally avoiding the risk of poor bonding between the glaze and the body due to expansion coefficient mismatch, thereby improving thermal shock resistance and effectively reducing the risk of glaze cracking.

[0029] Furthermore, this technical solution ensures that the whiteness of potassium feldspar is ≥50° and that of sodium feldspar is ≥45° by limiting the whiteness of the base flux raw materials to a sufficiently high intrinsic whiteness, laying the physical foundation for obtaining a high-whiteness glaze. Meanwhile, iron and titanium ions are the main factors causing yellowing and graying of the glaze. This technical solution limits the sum of TiO2 and Fe2O3 content in both potassium and sodium feldspar to less than 0.3%, fundamentally suppressing glaze color deviation from the mineral raw material level, which is beneficial for achieving high whiteness. In addition, the zirconium silicate introduced into the formula acts as a highly efficient opacifier, which, through its refraction and scattering effects in the glaze melt, helps to improve the hiding power and overall whiteness of the glaze layer.

[0030] Furthermore, this technical solution utilizes a high proportion and high purity of potassium feldspar and sodium feldspar as the main flux, introducing a large amount of potassium and sodium ions with strong network modification capabilities. These ions effectively disrupt the three-dimensional silicon-oxygen network structure, significantly reducing the viscosity of the glaze melt at high temperatures, thereby greatly improving its fluidity and spreadability. Simultaneously, calcium oxide and magnesium oxide, introduced through the calcination of talc and other raw materials, act as high-temperature fluxes, working synergistically with potassium oxide and sodium oxide to jointly regulate the viscosity, surface tension, and flow characteristics of the glaze melt (i.e., the glaze glass phase) generated during high-temperature melting. This allows the glaze to form a smooth, dense surface with a high glass phase content after firing, resulting in an excellent mirror-like reflection effect on a macroscopic scale, achieving high gloss.

[0031] Furthermore, the aforementioned glassy phase of the glaze, by encapsulating particles, filling grain boundary voids, and strengthening particle adhesion, blocks the channels for stain penetration, thereby endowing the glaze surface with excellent anti-fouling properties. In addition, as described above, the glaze layer formed after firing in this technical solution matches the coefficient of thermal expansion of the body in existing technologies, preventing glaze cracking after firing in the kiln and also contributing to ensuring anti-fouling performance.

[0032] Finally, during the high-temperature firing process, kaolin decomposes to produce aluminum oxide and silicon dioxide, quartz provides additional silicon dioxide, and dolomite and calcite decompose to produce calcium oxide. Calcium oxide reacts with aluminum oxide and silicon dioxide to form anorthite crystals (CaAl2Si2O8), and aluminum oxide and silicon dioxide can also react to form mullite crystals (3Al2O3·2SiO2). Dolomite and calcined talc decompose to produce magnesium oxide, which reacts with aluminum oxide and silicon dioxide in the system to form cordierite crystals (Mg2Al2Si2O8). 18 Anorthite, mullite, and cordierite crystals all possess high hardness, forming a physical support framework within the glaze layer to directly resist external pressure and wear. Simultaneously, zirconium silicate is anchored within the glass phase, hindering grain boundary slippage and deformation, thereby synergistically enhancing the material's macroscopic hardness and wear resistance. As described above, the glaze in this technical solution can match the coefficient of thermal expansion of the body in existing technologies, preventing glaze cracking after firing and ensuring both hardness and wear resistance.

[0033] It should be noted that this technical solution, through the optimization of the raw materials in the formula, can ensure the hardness and wear resistance of the glaze without adding zinc oxide, thereby helping to reduce raw material costs.

[0034] To further explain, the chemical composition of the potassium feldspar, calculated by mass percentage, includes 0.1–0.15% MgO, 0.3–0.4% CaO, 12.1–12.3% Al2O3, 65.4–66.6% SiO2, 10–11% K2O, 0.5–0.6% Na2O, 0.12–0.15% TiO2, and 0.08–0.12% Fe2O3, with the remainder being loss on ignition.

[0035] This technical solution preferably incorporates potassium feldspar with a TiO2 content of 0.12–0.15% and an Fe2O3 content of 0.08–0.12% by mass into the raw materials of the glaze. This helps to further mitigate the impact of TiO2 and Fe2O3 on whiteness and glaze cracking, thereby ensuring the performance of the glaze. Simultaneously, the high K2O content (10–11%) in the potassium feldspar helps to ensure its fluxing effect.

[0036] To further clarify, the albite, calculated by mass percentage, comprises 0.15–0.2% MgO, 0.05–0.1% CaO, 17.1–17.3% Al₂O₃, 67.2–67.4% SiO₂, 1.3–1.4% K₂O, 9–10% Na₂O, 0.05–0.1% TiO₂, and 0.05–0.1% Fe₂O₃, with the remainder being loss on ignition.

[0037] This technical solution preferably incorporates albite with a TiO2 content of 0.05–0.1% and an Fe2O3 content of 0.05–0.1% by mass into the raw materials of the glaze. This helps to further mitigate the impact of TiO2 and Fe2O3 on whiteness and glaze cracking, thereby ensuring the performance of the glaze. Simultaneously, the high Na2O content (9–10%) in the albite helps ensure its fluxing effect.

[0038] To further clarify, based on mass percentage, the potassium feldspar and sodium feldspar, when passed through a 200-mesh sieve, both have a residue of ≤8%.

[0039] This technical solution, by limiting the fineness of potassium feldspar and sodium feldspar, helps to ensure the dispersibility and high-temperature reactivity of potassium feldspar and sodium feldspar in the glaze slurry, thereby helping to ensure its performance.

[0040] Further explanation: the raw materials also include frit; calculated by mass parts, the surface glaze for sanitary ceramics includes the following raw materials: 18-25 parts potassium feldspar, 20-28 parts sodium feldspar, 18-25 parts quartz powder, 4-7 parts calcite, 2-4 parts kaolin, 2-5 parts dolomite, 8-12 parts zirconium silicate, 1-3 parts barium carbonate, 2-5 parts calcined talc powder, and 2-6 parts frit; The chemical composition of the fused block, calculated by mass percentage, includes 60-63% SiO2, 8-10% Al2O3, 0.05-0.10% Fe2O3, 0.01-0.05% TiO2, 8-12% CaO, 1-2% MgO, 3-4% K2O, 1-1.5% Na2O, and 3-6% ZnO, with the remainder being loss on ignition.

[0041] In a preferred embodiment of this technical solution, by introducing frit into the glaze formulation, the characteristics of the frit being calcined and forming a stable glassy phase are utilized. This not only helps to lower the firing temperature of the glaze but also helps to increase the content of the glassy phase. This results in a smoother, denser surface with a higher glassy phase content, which improves stain resistance and gloss. Simultaneously, by introducing frit into the glaze formulation, this technical solution also helps to make the melting behavior of the glaze smoother and more uniform, facilitating a tighter bond between the glaze layer and the body during firing and preventing glaze peeling. It should be noted that although the frit contains zinc oxide, resulting in the presence of zinc oxide in the glaze, the zinc oxide content in the glaze formulation is less than 0.5%, an extremely low level. This keeps the raw material cost of the glaze lower than that of traditional high-zinc glaze formulations.

[0042] A method for preparing sanitary ceramics, using the sanitary ceramic glaze as described above, includes the following steps: A. After mixing potassium feldspar, sodium feldspar, quartz powder, calcite, kaolin, dolomite, zirconium silicate, barium carbonate, calcined talc powder and frit evenly according to the formula, add sodium carboxymethyl cellulose, sodium tripolyphosphate and water and ball mill to obtain the basic glaze slurry; after the basic glaze slurry is subjected to primary sieving and secondary sieving, the surface glaze for sanitary ceramics is obtained. B. Apply a glaze to the surface of the sanitary ceramic body to form a glaze layer; wherein the coefficient of thermal expansion of the body is (215~240)×10. -6 / ℃; C. After drying, the product is calcined in a kiln to obtain sanitary ceramics; wherein the calcination temperature is 1200-1230℃.

[0043] This technical solution also proposes a method for preparing sanitary ceramics. The method is simple and easy to operate, and it helps to ensure high hardness, high wear resistance, excellent stain resistance, high gloss, and high whiteness while reducing raw material costs, minimizing cracking risks, and widening the firing temperature range. It should be noted that the green body in this solution is made by pressing and drying conventional ceramic blanks; further description of the ceramic blanks is not provided here.

[0044] Preferably, in step A, the amount of water added, calculated by mass percentage, is 33-50% of the dry material of the sanitary ceramic glaze, the amount of sodium carboxymethyl cellulose added is 0.3-0.5% of the dry material of the sanitary ceramic glaze, and the amount of sodium hexametaphosphate added is 0.4-0.8% of the dry material of the sanitary ceramic glaze. It should be noted that the dry material of the sanitary ceramic glaze refers to the mixture formed by mixing potassium feldspar, sodium feldspar, quartz powder, calcite, kaolin, dolomite, zirconium silicate, barium carbonate, calcined talc powder, and frit in the sanitary ceramic glaze formulation.

[0045] To further explain, in step A, the initial sieving specifically involves filtering the basic glaze slurry through a 120-mesh sieve and a 180-mesh sieve in sequence to obtain a coarse glaze slurry. The secondary sieving specifically involves adding sodium carboxymethyl cellulose to the coarse sieving glaze and mixing it evenly, then filtering it sequentially through a 200-mesh sieve and a 120-mesh sieve to obtain the surface glaze for sanitary ceramics; wherein, calculated by mass percentage, the amount of sodium carboxymethyl cellulose added is 0.1 to 0.2% of the dry material added to the surface glaze for sanitary ceramics.

[0046] This technical solution optimizes the specific methods of primary and secondary sieving. The primary sieving employs a two-stage filtration process, from coarse to fine (120-mesh to 180-mesh sieve), effectively removing coarse particles, unground mineral aggregates, and impurities (such as iron) that may be present in the first glaze slurry after ball milling, laying the foundation for a smooth and fine glaze surface. Subsequently, sodium carboxymethyl cellulose is added during the secondary sieving process to provide stable binding force and pseudoplastic rheology to the coarse slurry, preventing solid particle sedimentation. Finally, a reverse filtration process, from fine to coarse (200-mesh to 120-mesh sieve), is performed again to remove any small amounts of incompletely dispersed colloids or impurities that may have formed during the dissolution of sodium carboxymethyl cellulose, while maintaining the desired fineness. Through physical purification, rheological optimization, and final fine filtration, this process ensures that the glaze for sanitary ceramics possesses high uniformity, good suspension, and easy application, thereby guaranteeing high density, high gloss, and excellent surface smoothness of the glaze layer after firing.

[0047] To further explain, in step A, the specific gravity of the glaze used in sanitary ceramics is 1.75 to 1.85, and the fineness of the glaze used in sanitary ceramics is through a 325-mesh sieve, with a residue of 0.1 to 0.2% by mass percentage.

[0048] When the specific gravity of the glaze used in sanitary ceramics is too high, it 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 of the glaze is too low, its fluidity is too good, causing it to flow during application, similarly 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 glaze to 1.75–1.85, which helps ensure the quality of the resulting sanitary ceramic glaze surface. It should be noted that glaze streaks refer to areas where the glaze layer is thicker than others, or even absent.

[0049] Furthermore, this technical solution limits the fineness of the glaze used in sanitary ceramics, ensuring that the raw materials in the glaze are evenly dispersed, thereby guaranteeing the product's performance.

[0050] To further explain, in step B, the glaze thickness of the sanitary ceramic surface glaze is 0.7–0.9 mm.

[0051] If the glaze thickness of sanitary ceramics is too thin, it will easily lead to glaze defects such as leakage, which will affect the stain resistance and wear resistance. If the glaze thickness is too thick, it will result in excessively high production costs. Therefore, this technical solution limits the glaze thickness of sanitary ceramics to 0.7–0.9 mm, which helps to ensure the stain resistance and wear resistance of sanitary ceramics while reducing costs.

[0052] A sanitary ceramic, prepared using the sanitary ceramic preparation method described above, wherein the sanitary ceramic has a Mohs hardness ≥5, abrasion resistance at least grade B, stain resistance grade 5, gloss ≥90°, and whiteness ≥90°.

[0053] This technical solution also proposes a sanitary ceramic prepared by the above-mentioned method, which has a Mohs hardness ≥5, wear resistance at least B grade, stain resistance grade 5, gloss ≥90°, and whiteness ≥90°, which helps to ensure that the obtained sanitary ceramic has high hardness, high wear resistance, excellent stain resistance, high gloss and high whiteness.

[0054] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0055] Thermal shock resistance: Place the sanitary ware in a furnace preheated to 1100℃, keep it at that temperature for 20 minutes, then quench it in room temperature water for 3 minutes. After drying, observe whether there are any cracks in the sanitary ware.

[0056] Gloss: The gloss of sanitary ceramics was tested using an LS191 ceramic gloss meter, and the test was performed in parallel 5 times. The average value of the 5 tests was taken.

[0057] Stain resistance: The test method of GB / T3810.14-2016 "Test Methods for Ceramic Tiles Part 14: Determination of Stain Resistance - Building Materials Standard" uses a green dye in light oil as a staining agent to test the stain resistance of the glaze of sanitary ceramics. A stain resistance level of 5 is considered qualified.

[0058] Abrasion resistance: Five 100mm × 100mm samples were cut from the sanitary ceramics and dried at 110±5℃ to constant weight. The initial mass of each sample was weighed and recorded. The sample was clamped in a metal fixture with the glaze side facing up. Grinding media was added through the feed hole of the metal fixture, and the lid was closed. The grinding equipment was started, the speed was set to 6000 rpm, and grinding was performed. After completion, the samples were removed, rinsed with running water, and dried again at 110±5℃. The mass of each sample after grinding was then weighed. The abrasion value was obtained by calculating the difference in mass before and after grinding for each sample. The average abrasion value of the five samples was then taken. If the sample was contaminated with rust, it could be wiped with 10% (volume fraction) hydrochloric acid, rinsed immediately with running water, dried, and then weighed. The specific abrasion resistance grade standards are shown in the table below:

[0059] Mohs hardness: The hardness of sanitary ceramics is measured according to the test method of the standard "ASTM C1895-19 Standard Test Method for Determination of Mohs Scratch Hardness of Ceramic Tiles".

[0060] Whiteness: The whiteness of sanitary ceramics is measured according to the test method of the standard "QB / T 1503-1992 Test Method for Whiteness of Daily-use Ceramics".

[0061] In the embodiments and comparative examples of the present invention, the chemical composition of potassium feldspar, calculated by mass percentage, includes 0.12% MgO, 0.4% CaO, 12.2% Al2O3, 66.2% SiO2, 11% K2O, 0.6% Na2O, 0.12% TiO2, and 0.1% Fe2O3, with the remainder being loss on ignition. Based on mass percentage, albite comprises 0.2% MgO, 0.1% CaO, 17.1% Al2O3, 67.4% SiO2, 1.4% K2O, 10% Na2O, 0.1% TiO2, and 0.1% Fe2O3, with the remainder being loss on ignition. The chemical composition of the fused block, calculated by mass percentage, includes 62% SiO2, 39% Al2O3, 0.1% Fe2O3, 0.05% TiO2, 10% CaO, 2% MgO, 4% K2O, 1.2% Na2O, and 4% ZnO, with the remainder being loss on ignition.

[0062] Example 1 A. Mix 20 parts potassium feldspar, 24 parts sodium feldspar, 23 parts quartz powder, 6 parts calcite, 3 parts kaolin, 4 parts dolomite, 10 parts zirconium silicate, 2 parts barium carbonate, 3 parts calcined talc powder, and 5 parts frit according to mass percentage. Then, add sodium carboxymethyl cellulose, sodium tripolyphosphate, and water, and ball mill to obtain a basic glaze slurry. After the basic glaze slurry is subjected to a primary sieve and a secondary sieve, a surface glaze for sanitary ceramics is obtained. Among them, the whiteness of potassium feldspar is 55°, and according to mass percentage, potassium feldspar passes through a 200-mesh sieve with a 7% residue; the whiteness of sodium feldspar is 48°, and according to mass percentage, sodium feldspar passes through a 200-mesh sieve with a 6% residue; the specific gravity of the surface glaze for sanitary ceramics is 1.75, and according to mass percentage, the surface glaze for sanitary ceramics... The glaze is fined through a 325-mesh sieve, with a residue of 0.1%. The amount of water added, calculated by mass percentage, is 50% of the dry material of the sanitary ceramic glaze; the amount of sodium carboxymethyl cellulose added is 0.4% of the dry material of the sanitary ceramic glaze; and the amount of sodium hexametaphosphate added is 0.4% of the dry material of the sanitary ceramic glaze. The initial sieving process involves filtering the base glaze slurry through a 120-mesh sieve and then a 180-mesh sieve to obtain a coarse glaze slurry. The second sieving process involves adding sodium carboxymethyl cellulose (0.1% of the dry material of the sanitary ceramic glaze) to the coarse glaze slurry and mixing thoroughly. Then, the mixture is filtered through a 200-mesh sieve and then a 120-mesh sieve to obtain the sanitary ceramic glaze. B. Apply a glaze cloth to the surface of the sanitary ceramic body to form a glaze layer; wherein the coefficient of thermal expansion of the body is 220×10. -6 / ℃; The glaze thickness for sanitary ceramics is 0.8mm; C. After drying, the product is fired in a kiln to obtain sanitary ceramics; the firing temperature is 1200℃.

[0063] Example 2 A. Mix 18 parts potassium feldspar, 28 parts sodium feldspar, 18 parts quartz powder, 7 parts calcite, 4 parts kaolin, 3 parts dolomite, 12 parts zirconium silicate, 1 part barium carbonate, 3 parts calcined talc powder, and 6 parts frit according to mass percentages. Then, add sodium carboxymethyl cellulose, sodium tripolyphosphate, and water, and ball mill to obtain a basic glaze slurry. After passing the basic glaze slurry through a primary sieve and a secondary sieve, obtain a surface glaze for sanitary ceramics. The whiteness of potassium feldspar is 50°, and according to mass percentage, potassium feldspar passing through a 200-mesh sieve leaves a residue of 8%. The whiteness of sodium feldspar is 45°, and according to mass percentage, sodium feldspar passing through a 200-mesh sieve leaves a residue of 8%. The specific gravity of the surface glaze for sanitary ceramics is 1.8, and according to mass percentage, the surface glaze for sanitary ceramics... The glaze has a fineness that passes through a 325-mesh sieve, with a residue of 0.1%. Based on mass percentage, the amount of water added is 40% of the dry material of the sanitary ceramic glaze, the amount of sodium carboxymethyl cellulose added is 0.3% of the dry material of the sanitary ceramic glaze, and the amount of sodium hexametaphosphate added is 0.5% of the dry material of the sanitary ceramic glaze. The initial sieving process involves filtering the base glaze slurry through a 120-mesh sieve and then through a 180-mesh sieve to obtain a coarse glaze slurry. The second sieving process involves adding sodium carboxymethyl cellulose (0.2% of the dry material of the sanitary ceramic glaze) to the coarse glaze slurry and mixing thoroughly. Then, the mixture is filtered through a 200-mesh sieve and then through a 120-mesh sieve to obtain the sanitary ceramic glaze. B. Apply a glaze cloth to the surface of the sanitary ceramic body to form a glaze layer; wherein the coefficient of thermal expansion of the body is 215×10. -6 / ℃; The glaze thickness for sanitary ceramics is 0.7mm; C. After drying, the product is fired in a kiln to obtain sanitary ceramics; the firing temperature is 1220℃.

[0064] Example 3 A. Mix 25 parts potassium feldspar, 20 parts sodium feldspar, 25 parts quartz powder, 5 parts calcite, 2 parts kaolin, 5 parts dolomite, 8 parts zirconium silicate, 3 parts barium carbonate, 5 parts calcined talc powder, and 2 parts frit according to mass percentages. Then add sodium carboxymethyl cellulose, sodium tripolyphosphate, and water and ball mill to obtain a basic glaze slurry. After the basic glaze slurry is subjected to a primary sieve and a secondary sieve, a surface glaze for sanitary ceramics is obtained. Among them, the whiteness of potassium feldspar is 52°, and according to mass percentage, potassium feldspar passes through a 200-mesh sieve with a 6% residue; the whiteness of sodium feldspar is 45°, and according to mass percentage, sodium feldspar passes through a 200-mesh sieve with an 8% residue; the specific gravity of the surface glaze for sanitary ceramics is 1.85, and according to mass percentage, the surface glaze for sanitary ceramics... The glaze has a fineness that passes through a 325-mesh sieve, with a residue of 0.2%. Based on mass percentage, the amount of water added is 35% of the dry material of the sanitary ceramic glaze, the amount of sodium carboxymethyl cellulose added is 0.3% of the dry material of the sanitary ceramic glaze, and the amount of sodium hexametaphosphate added is 0.8% of the dry material of the sanitary ceramic glaze. The initial sieving process involves filtering the base glaze slurry through a 120-mesh sieve and then through a 180-mesh sieve to obtain a coarse glaze slurry. The second sieving process involves adding sodium carboxymethyl cellulose (0.2% of the dry material of the sanitary ceramic glaze) to the coarse glaze slurry and mixing thoroughly. Then, the mixture is filtered through a 200-mesh sieve and then through a 120-mesh sieve to obtain the sanitary ceramic glaze. B. Apply a glaze cloth to the surface of the sanitary ceramic body to form a glaze layer; wherein the coefficient of thermal expansion of the body is 240×10. -6 / ℃; The glaze thickness for sanitary ceramics is 0.9mm; C. After drying, the product is fired in a kiln to obtain sanitary ceramics; the firing temperature is 1210℃.

[0065] Comparative Example 1 The preparation method and raw materials of this comparative example are the same as those of Example 1, except that zirconium silicate is not added in this comparative example.

[0066] The performance of the sanitary ceramics prepared in the examples and comparative examples was tested, and the results are shown in Table 1 below: Table 1. Performance test results of different sanitary ceramics in the examples and comparative examples.

[0067] As shown in Table 1, the sanitary ceramics obtained by this technical solution have a Mohs hardness of ≥5, wear resistance of at least Grade B, stain resistance of Grade 5, gloss of ≥90°, and whiteness of ≥90°. They possess high hardness, high wear resistance, excellent stain resistance, high gloss, and high whiteness to meet actual usage requirements.

[0068] 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 glaze for sanitary ceramics, characterized in that, The raw materials, calculated by weight, include the following: 18-25 parts potassium feldspar, 20-28 parts sodium feldspar, 18-25 parts quartz powder, 4-7 parts calcite, 2-4 parts kaolin, 2-5 parts dolomite, 8-12 parts zirconium silicate, 1-3 parts barium carbonate, and 2-5 parts calcined talc powder, and the raw materials do not contain zinc oxide. The whiteness of the potassium feldspar is ≥50°, and the chemical composition of the potassium feldspar includes K2O, TiO2 and Fe2O3. Calculated by mass percentage, the K2O content in the potassium feldspar is ≥10%, and the sum of the contents of TiO2 and Fe2O3 is <0.3%. The whiteness of the albite is ≥45°, and the chemical composition of the albite includes K2O, TiO2 and Fe2O3. Calculated by mass percentage, the Na2O content in the albite is ≥9%, and the sum of the contents of TiO2 and Fe2O3 is <0.3%.

2. A glaze for sanitary ceramics according to claim 1, characterized in that, The chemical composition of the potassium feldspar, calculated by mass percentage, includes 0.1–0.15% MgO, 0.3–0.4% CaO, 12.1–12.3% Al2O3, 65.4–66.6% SiO2, 10–11% K2O, 0.5–0.6% Na2O, 0.12–0.15% TiO2, and 0.08–0.12% Fe2O3, with the remainder being loss on ignition.

3. A glaze for sanitary ceramics according to claim 1, characterized in that, The albite, calculated by mass percentage, comprises 0.15–0.2% MgO, 0.05–0.1% CaO, 17.1–17.3% Al₂O₃, 67.2–67.4% SiO₂, 1.3–1.4% K₂O, 9–10% Na₂O, 0.05–0.1% TiO₂, and 0.05–0.1% Fe₂O₃, with the remainder being loss on ignition.

4. The glaze for sanitary ceramics according to claim 1, characterized in that, Based on mass percentage, the potassium feldspar and sodium feldspar, when passed through a 200-mesh sieve, have a residue of ≤8%.

5. A glaze for sanitary ceramics according to claim 1, characterized in that, The raw materials also include frit; calculated by mass parts, the surface glaze for sanitary ceramics includes the following raw materials: 18-25 parts potassium feldspar, 20-28 parts sodium feldspar, 18-25 parts quartz powder, 4-7 parts calcite, 2-4 parts kaolin, 2-5 parts dolomite, 8-12 parts zirconium silicate, 1-3 parts barium carbonate, 2-5 parts calcined talc powder, and 2-6 parts frit; The chemical composition of the fused block, calculated by mass percentage, includes 60-63% SiO2, 8-10% Al2O3, 0.05-0.10% Fe2O3, 0.01-0.05% TiO2, 8-12% CaO, 1-2% MgO, 3-4% K2O, 1-1.5% Na2O, and 3-6% ZnO, with the remainder being loss on ignition.

6. A method for preparing sanitary ceramics, characterized in that, Using the sanitary ceramic glaze as described in any of claims 5 includes the following steps: A. After mixing potassium feldspar, sodium feldspar, quartz powder, calcite, kaolin, dolomite, zirconium silicate, barium carbonate, calcined talc powder and frit evenly according to the formula, add sodium carboxymethyl cellulose, sodium tripolyphosphate and water and ball mill to obtain the basic glaze slurry; after the basic glaze slurry is subjected to primary sieving and secondary sieving, the surface glaze for sanitary ceramics is obtained. B. Apply a glaze to the surface of the sanitary ceramic body to form a glaze layer; wherein the coefficient of thermal expansion of the body is (215~240)×10. -6 / ℃; C. After drying, the product is calcined in a kiln to obtain sanitary ceramics; wherein the calcination temperature is 1200-1230℃.

7. The method for preparing sanitary ceramics according to claim 6, characterized in that, In step A, the initial sieving specifically involves filtering the base glaze slurry through a 120-mesh sieve and a 180-mesh sieve in sequence to obtain a coarse glaze slurry. The secondary sieving specifically involves adding sodium carboxymethyl cellulose to the coarse sieving glaze and mixing it evenly, then filtering it sequentially through a 200-mesh sieve and a 120-mesh sieve to obtain the surface glaze for sanitary ceramics; wherein, calculated by mass percentage, the amount of sodium carboxymethyl cellulose added is 0.1 to 0.2% of the dry material added to the surface glaze for sanitary ceramics.

8. The method for preparing sanitary ceramics according to claim 6, characterized in that, In step A, the specific gravity of the glaze used in sanitary ceramics is 1.75 to 1.85, and the fineness of the glaze used in sanitary ceramics is through a 325-mesh sieve, with a residue of 0.1 to 0.2% by mass percentage.

9. A method for preparing sanitary ceramics according to claim 6, characterized in that, In step B, the thickness of the glaze used for sanitary ceramics is 0.7 to 0.9 mm.

10. A sanitary ceramic, characterized in that, The sanitary ceramic is prepared using the preparation method of any one of claims 5 to 9, wherein the sanitary ceramic has a Mohs hardness ≥ 5, abrasion resistance at least grade B, stain resistance grade 5, gloss ≥ 90°, and whiteness ≥ 90°.

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