Black matte glaze for sanitary wares, sanitary wares and method for manufacturing the same

Abstract

The application discloses a black matte glaze for sanitary wares, the sanitary wares and a preparation method thereof, and relates to the technical field of ceramics. The black matte glaze comprises a base glaze and a cobalt-containing colorant. The base glaze comprises the following components: 8-15 parts of potassium feldspar, 25-36 parts of quartz powder, 1-2 parts of calcined zinc oxide, 12-15 parts of dolomite, 7-9 parts of wollastonite, 3-5 parts of high-clay for glaze, 1-3 parts of calcined alumina, 2-8 parts of barium carbonate, 4-7 parts of calcined talc and 10-17 parts of Jiangxi lithium porcelain stone. The cobalt-containing colorant is 6-11 parts. The components of the black matte glaze for sanitary wares are beneficial to the crystallization of calcium, magnesium and barium elements, and can avoid the influence of high aluminum content on the color development of the cobalt-containing colorant. The Jiangxi lithium porcelain stone is introduced to reduce the free quartz and quartz crystal phase and is beneficial to the crystallization of potassium feldspar and wollastonite. The base glaze can avoid the problem of low glaze melting temperature caused by the introduction of the cobalt-containing colorant, and can avoid the phenomenon of glaze surface haze, roughness and dirt absorption.

Description

Technical Field

[0001] This invention relates to the field of ceramic technology, and in particular to a black matte glaze for sanitary ware, sanitary ware, and a method for preparing the same. Background Technology

[0002] Matte glaze, also known as matte glaze, is achieved by introducing certain components into the glaze, allowing these components to form compounds with components in the glass matrix. In the molten state, these compounds precipitate corresponding crystals, resulting in a frosted texture without gloss, thus achieving a matte finish. In existing technologies, adding limestone to the glaze components will precipitate anorthite or wollastonite; increasing the Al2O3 content will precipitate mullite; and increasing the BaO content will precipitate barium feldspar. Black matte glaze is a type of matte glaze; by adding colorants such as cobalt black to the matte glaze formula, a delicate and pure black glaze can be obtained.

[0003] In existing technologies, sanitary ware, due to its long firing cycle and slow cooling time in the kiln, is conducive to crystallization, making it easy for ordinary light-colored matte glazes to achieve the desired crystallization effect. However, black matte glazes, due to the addition of a large amount of cobalt black material, have a lower melting temperature. During the high-temperature firing stage, bubbles are prone to appear on the glaze surface, and melting and precipitation easily occur at the edges of these bubbles, promoting crystal precipitation. This results in a grayish-black hazy substance on the glaze surface, which, under magnification, reveals dense bubbles and crystal spots, causing a hazy, rough, and easily stain-absorbing glaze. Therefore, currently, sanitary ware products are only available with white or light-colored matte glazes, with very few black matte glaze products. A few manufacturers have attempted to launch small quantities of black matte glaze products, but these products suffer from poor smoothness, a hazy glaze surface, and a rough glaze surface. Summary of the Invention

[0004] The purpose of this invention is to provide a black matte glaze for sanitary ware, addressing the problems of poor fineness, hazy surface, and roughness in existing black matte glazes for sanitary ware. Furthermore, this invention aims to provide a black matte sanitary ware and its preparation method to meet market demand for black matte sanitary ware.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] This invention provides a black matte glaze for sanitary ware, comprising a base glaze and a cobalt-containing colorant; the base glaze comprises the following components by weight: 8-15 parts potassium feldspar, 25-36 parts quartz powder, 1-2 parts calcined zinc oxide, 12-15 parts dolomite, 7-9 parts wollastonite, 3-5 parts kaolinite for glaze, 1-3 parts calcined alumina, 2-8 parts barium carbonate, 4-7 parts calcined talc, and 10-17 parts Jiangxi lithium porcelain stone; the cobalt-containing colorant comprises 6-11 parts by weight.

[0007] In the black matte glaze for sanitary ware, the cobalt-containing colorant includes 5 to 8 parts of cobalt black material and 1 to 3 parts of cobalt blue material.

[0008] The black matte glaze for sanitary wares also includes 0-3 parts of high-zinc emulsion frit powder.

[0009] The black matte glaze for sanitary wares comprises, by mass percentage, 62.00–63.00% SiO2, 7.60–8.60% Al2O3, 0.10–0.50% Fe2O3, 0.01–0.05% TiO2, 8.25–9.25% CaO, 4.25–5.15% MgO, 1.50–1.95% K2O, 1.05–1.55% Na2O, 0.20–0.60% Li2O, 0.00–0.05% ZrO2, 0.90–1.60% ZnO, 0.01–0.40% B2O3, 2.10–5.50% BaO, and 7.80–8.85% loss on ignition.

[0010] In the black matte glaze for sanitary ware, the ratio of Al2O3 to SiO2 content is 1:(6-9).

[0011] The black matte glaze for sanitary ware has a particle size of 1–25 μm.

[0012] The present invention also provides a black matte sanitary ware, wherein the surface of the sanitary ware is provided with a matte black glaze layer; the glaze layer is formed by firing the aforementioned black matte glaze for sanitary ware.

[0013] The matte black sanitary ware is made of either porcelain or stoneware.

[0014] The present invention also provides a method for preparing black matte sanitary ware, comprising the following steps: applying black matte glaze to the raw ceramic sanitary ware body, and firing it to obtain a matte black sanitary ware ceramic product.

[0015] In the preparation method of the aforementioned matte black sanitary ware, the firing temperature curve includes:

[0016] (1) It took 180 minutes to heat the temperature from room temperature to 480℃.

[0017] (2) It took 200 minutes to heat the temperature from 480℃ to 990℃.

[0018] (3) It took 220 minutes to raise the temperature from 990℃ to 1210℃;

[0019] (4) Keep warm at 1210℃ for 30 minutes;

[0020] (5) The temperature was reduced from 1210℃ to 1100℃ in 60 minutes;

[0021] (6) The temperature dropped from 1100℃ to 680℃ in 30 minutes;

[0022] (7) It took 240 minutes to cool from 680℃ to room temperature.

[0023] One of the technical solutions in this invention can have the following beneficial effects:

[0024] The black matte glaze for sanitary wares has a high silicon content and a low aluminum content, belonging to a high-silicon, low-aluminum system. This promotes the precipitation of calcium, magnesium, and barium crystals while avoiding the negative impact of high aluminum content on the color development of cobalt-containing pigments. After firing, a black matte glaze surface is formed. Furthermore, the introduction of Jiangxi lithium porcelain stone not only melts free quartz, reducing the precipitation of free quartz and quartz crystal phases, but also facilitates the precipitation of more anorthite and wollastonite crystals. It also lowers the coefficient of thermal expansion of the glaze, improving its thermal shock resistance. The base glaze also avoids the problem of lower glaze melting temperature caused by the introduction of cobalt-containing pigments, reducing the occurrence of bubbles on the glaze surface during the high-temperature firing stage, and preventing undesirable phenomena such as a cloudy, rough, and easily absorbing dirt surface. Detailed Implementation

[0025] The technical solution of the present invention will be further illustrated below through specific embodiments. To facilitate understanding of the present invention, a more comprehensive description is provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0026] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] This invention provides a black matte glaze for sanitary ware, comprising a base glaze and a cobalt-containing colorant; the base glaze comprises the following components by weight: 8-15 parts potassium feldspar, 25-36 parts quartz powder, 1-2 parts calcined zinc oxide, 12-15 parts dolomite, 7-9 parts wollastonite, 3-5 parts kaolinite for glaze, 1-3 parts calcined alumina, 2-8 parts barium carbonate, 4-7 parts calcined talc, and 10-17 parts Jiangxi lithium porcelain stone; the cobalt-containing colorant comprises 6-11 parts by weight.

[0029] Currently, the matte glaze systems for sanitary ware are mostly high-aluminum, low-silicon systems, with low silicon content and high aluminum content. These include zinc-barium matte systems, calcium-magnesium matte systems, and mixed matte systems. While high-silicon, low-aluminum systems can theoretically produce a fine matte finish, the high quartz content makes quartz melting difficult, leading to the precipitation of quartz crystals, a narrow firing range, and difficulty in controlling the firing temperature. Furthermore, the high aluminum content in high-aluminum, low-silicon systems hinders the development of cobalt colorants, and the high viscosity of the glaze at high temperatures makes degassing difficult, resulting in bubbles on the glaze surface. Melting occurs at the edges of these bubbles, causing a hazy, rough glaze surface, making production difficult.

[0030] The black matte glaze for sanitary ware introduces Li2O through Jiangxi lithium porcelain stone to replace an equal amount of Na2O and K2O. Due to the high electrostatic field of lithium ions, their fluxing power is extremely strong. Utilizing the strong fluxing power of Li2O, free quartz is melted, reducing the precipitation of free quartz and quartz crystal phases, which is conducive to the precipitation of more anorthite and wollastonite crystals. Furthermore, it can also reduce the coefficient of thermal expansion of the melt and improve the thermal shock resistance of the glaze.

[0031] The black matte glaze for sanitary wares contains a large amount of dolomite and wollastonite, resulting in a high CaO content. Simultaneously, it has a high silicon content and a low aluminum content, which facilitates the precipitation of anorthite crystals during firing. Furthermore, the dolomite also has a high MgO content, causing magnesium to precipitate along with calcium, forming diopside, enstatite, and other pyroxene crystals. These calcium-magnesium crystals in the glaze layer contribute to the matte effect. ZnO is introduced through the calcination of zinc oxide, which forms crystal nuclei and promotes crystallization. Additionally, BaO is introduced through barium carbonate, which precipitates barium feldspar during firing. The small crystal phase of barium feldspar produces a soft, delicate glaze surface with excellent matting properties. Utilizing the excellent matting effect of BaO, the amount of barium carbonate can be adjusted to produce matte glazes with varying gloss levels, meeting the needs of different customers and markets.

[0032] The black matte glaze for sanitary ware, applied to sanitary ware, comprises cobalt pigment, dolomite, wollastonite, calcined zinc oxide, and barium carbonate. The composition of this black matte glaze is high in silicon and low in aluminum, belonging to a high-silicon, low-aluminum system. This promotes the precipitation of calcium, magnesium, and barium crystals while avoiding the negative impact of high aluminum content on the color development of the cobalt pigment. After firing, a black matte glaze surface is formed. Furthermore, the introduction of Jiangxi lithium porcelain stone not only dissolves free quartz, reducing the precipitation of free quartz and quartz crystal phases, but also facilitates the precipitation of more calcium feldspar and wollastonite crystals. It also lowers the coefficient of thermal expansion of the glaze, improving its thermal shock resistance. The composition of the base glaze avoids the problem of a lower melting temperature due to the introduction of cobalt pigment, reduces the occurrence of bubbles on the glaze surface during the high-temperature firing stage, and prevents undesirable phenomena such as a cloudy, rough, and easily absorbing dirt surface.

[0033] Specifically, the cobalt-containing colorant includes 5-8 parts cobalt black and 1-3 parts cobalt blue. The color of the black matte glaze for sanitary ware can be adjusted by the content of cobalt black and cobalt blue. The ratio between cobalt black and cobalt blue can be adjusted according to actual needs to achieve the desired color.

[0034] Specifically, it also includes 0-3 parts of high-zinc emulsion frit powder. The high-zinc emulsion frit is specifically 809 frit, which has a high degree of bonding between the body and the glaze. The high-zinc emulsion frit acts as a flux in the glaze, which can further adjust the initial melting temperature of the glaze and the viscosity and surface tension of the glaze at high temperatures. It can effectively improve the quality of the glaze surface, making the glaze surface smooth and flat, free of defects such as pinholes and bubbles, and reducing the occurrence of bubbles in the glaze surface during the high-temperature firing stage.

[0035] Specifically, the chemical composition of the base glaze, by mass percentage, includes 62.00–63.00% SiO2, 7.60–8.60% Al2O3, 0.10–0.50% Fe2O3, 0.01–0.05% TiO2, 8.25–9.25% CaO, 4.25–5.15% MgO, 1.50–1.95% K2O, 1.05–1.55% Na2O, 0.20–0.60% Li2O, 0.00–0.05% ZrO2, 0.90–1.60% ZnO, 0.01–0.40% B2O3, 2.10–5.50% BaO, and 7.80–8.85% loss on ignition.

[0036] In a specific embodiment of the present invention, the black matte glaze for sanitary ware includes the chemical components described above. However, because sanitary ware requires a long firing time, excessive ZnO can lead to overly large crystal nuclei and excessive crystallization, resulting in a rough and hard glaze surface. Therefore, the ZnO content is limited to 0.90–1.60%.

[0037] In existing spraying technologies, sanitary ware typically employs a glazing method due to its complex structure. However, the glaze sprayed from a spray gun can result in an uneven surface, requiring extended high-temperature holding time to smooth it out. Furthermore, since most sanitary ware products are glazed directly on vertical surfaces, it's crucial to prevent excessive high-temperature fluidity of the glaze, which can lead to glaze runs. Li₂O can enhance the high-temperature fluidity of the glaze; by adding 0.20–0.60% Li₂O, a suitable high-temperature fluidity can be adjusted, achieving a smooth glaze surface while avoiding glaze runs. Therefore, adding Jiangxi lithium porcelain stone to the glaze can further improve its high-temperature fluidity, resulting in a smoother glaze surface and thus improving glaze quality.

[0038] Specifically, the ratio of Al2O3 to SiO2 in the black matte glaze for sanitary ware is 1:(6-9). Using this Al2O3 to SiO2 ratio results in a high silicon content and a low aluminum content, belonging to a high-silicon, low-aluminum system. In this high-silicon, low-aluminum system, due to the CaO content of 8.25-9.25%, calcium feldspar crystals will precipitate in the molten state, producing a matte, calcium-based glaze effect with a fine finish. Furthermore, due to the BaO content of 2.10-5.50%, the glaze has a soft luster.

[0039] Specifically, the particle size of the black matte glaze used in the sanitary ware is 1–25 μm.

[0040] The black matte glaze for sanitary ware is produced through ultra-fine grinding, which reduces the particle size of quartz. This facilitates the melting of quartz at high temperatures, reduces the appearance of free quartz and quartz crystal phases, and promotes the crystallization of a large amount of anorthite and wollastonite, preventing excessive crystal growth and resulting in a finer and softer glaze surface. Furthermore, it facilitates the dispersion of different substances, increases the contact area, promotes the mutual fusion of different substances at high temperatures to form a eutectic, and promotes the dispersion of cobalt-containing colorants, thus enhancing color development. In addition, it increases the surface area of ​​materials, which is beneficial for high-temperature chemical reactions.

[0041] The present invention also provides a black matte sanitary ware, wherein the surface of the sanitary ware is provided with a matte black glaze layer; the glaze layer is formed by firing the aforementioned black matte glaze for sanitary ware.

[0042] In one specific embodiment of the present invention, a black matte glaze for sanitary ware is applied to the surface of the sanitary ware blank by spraying, with a spraying pressure of 0.3 to 0.45 MPa and a spraying flow rate of 540 to 580 ml / 30 sec.

[0043] Optionally, the raw material of the sanitary ware includes either porcelain or stoneware. The matte black finish of the sanitary ware can be used on both porcelain and stoneware materials, matching the coefficients of expansion of the glaze and body of the two materials, thus ensuring good adhesion between the glaze and the body.

[0044] The present invention also provides a method for preparing black matte sanitary ware, comprising the following steps: applying black matte glaze to the raw ceramic sanitary ware body, and firing it to obtain a matte black sanitary ware ceramic product.

[0045] The black matte glaze for sanitary ware adopts a high-silicon, low-aluminum system. Utilizing the strong fluxing power of Li2O, it melts free quartz, reducing the precipitation of free quartz and quartz crystal phases. This facilitates the precipitation of more anorthite and wollastonite crystals, thereby achieving the matte effect of the high-silicon, low-aluminum system. At the same time, the reduced aluminum content is beneficial for the color development of cobalt-containing pigments, allowing the glaze to exhibit a pure black color and avoiding the problem of grayish glaze color.

[0046] Specifically, the firing temperature profile includes:

[0047] (1) It took 180 minutes to heat the temperature from room temperature to 480℃.

[0048] (2) It took 200 minutes to heat the temperature from 480℃ to 990℃.

[0049] (3) It took 220 minutes to raise the temperature from 990℃ to 1210℃;

[0050] (4) Keep warm at 1210℃ for 30 minutes;

[0051] (5) The temperature was reduced from 1210℃ to 1100℃ in 60 minutes;

[0052] (6) The temperature dropped from 1100℃ to 680℃ in 30 minutes;

[0053] (7) It took 240 minutes to cool from 680℃ to room temperature.

[0054] The firing process can be specifically referred to the existing sanitary ware firing process. In a specific embodiment of the present invention, the black matte sanitary ware is fired once in a tunnel kiln and fired through the above temperature curve. The black matte sanitary ware first undergoes three heating steps (1) to (3) to reach the firing temperature of the sanitary ware, so that the different components are fully melted at high temperature and bubbles are discharged; then it is kept at a temperature for 30 minutes to allow the different components to fully react and generate glassy compounds with the same chemical composition as anorthite, diopside, wollastonite, etc.; then it undergoes segmented cooling steps (5) to (7) to allow the crystals of anorthite, diopside, and wollastonite to fully precipitate.

[0055] Performance testing:

[0056] Gloss: The gloss of sanitary ware ceramic products was tested in accordance with GB 3295-1982, "Method for Determination of Gloss of Daily-use Ceramic Ware".

[0057] Glaze color: Observe whether the color of the sanitary ware ceramic products is normal. A matte black color is acceptable.

[0058] Glaze appearance: Use a magnifying glass to observe the glaze surface to see if there are bubbles or crystal spots. Also observe the overall appearance of the glaze surface. The presence of bubbles or crystal spots, or a cloudy or rough glaze surface indicates defects.

[0059] Example Group A

[0060] A method for preparing a black matte glaze for sanitary ware includes the following steps:

[0061] Potassium feldspar, quartz powder, calcined zinc oxide, dolomite, wollastonite, kaolin for glaze, calcined alumina, barium carbonate, calcined talc, and Jiangxi lithium porcelain stone were added to a ball mill according to the proportions in Table 1. Water and milling agent were added, and the mixture was ball-milled until the residue on a 325-mesh sieve was less than 0.05%. Then, high-cobalt black pigment was added, and the ball milling continued. The balls were discharged, the specific gravity was adjusted to 1.80, and the mixture was sieved to obtain a black matte glaze for sanitary ware. The particle size distribution of the black matte glaze for sanitary ware was as follows: D25 = 1.01 μm, D50 = 3.78 μm, D90 = 16.72 μm, and D97 = 24.70 μm.

[0062] Table 1 - Distribution Ratio of Each Group

[0063]

[0064] The chemical composition of the base glaze in Example 1, by mass percentage, includes 62.53% SiO2, 8.45% Al2O3, 0.15% Fe2O3, 0.03% TiO2, 8.78% CaO, 4.59% MgO, 1.75% K2O, 1.15% Na2O, 0.28% Li2O, 0.01% ZrO2, 1.08% ZnO, 0.20% B2O3, 2.42% BaO, and 8.57% loss on ignition.

[0065] The chemical composition of the base glaze in Example 2, by mass percentage, includes 62.05% SiO2, 7.73% Al2O3, 0.11% Fe2O3, 0.02% TiO2, 8.54% CaO, 4.27% MgO, 1.53% K2O, 1.08% Na2O, 0.20% Li2O, 0.00% ZrO2, 1.02% ZnO, 0.10% B2O3, 5.45% BaO, and 7.87% loss on ignition.

[0066] The chemical composition of the base glaze in Example 3, by mass percentage, includes 62.78% SiO2, 8.36% Al2O3, 0.14% Fe2O3, 0.03% TiO2, 8.62% CaO, 4.34% MgO, 1.51% K2O, 1.06% Na2O, 0.34% Li2O, 0.01% ZrO2, 1.59% ZnO, 0.20% B2O3, 3.18% BaO, and 7.82% loss on ignition.

[0067] The chemical composition of the base glaze in Example 4, by mass percentage, includes 62.54% SiO2, 8.47% Al2O3, 0.14% Fe2O3, 0.03% TiO2, 8.72% CaO, 4.61% MgO, 1.76% K2O, 1.16% Na2O, 0.28% Li2O, 0.00% ZrO2, 1.03% ZnO, 0.04% B2O3, 2.40% BaO, and 8.79% loss on ignition.

[0068] Comparative Example 1

[0069] The preparation method of Comparative Example 1 is the same as that of Example 1, except that Comparative Example 1 includes the following components by weight: 12.5 parts potassium feldspar, 26.5 parts quartz powder, 1 part calcined zinc oxide, 15 parts dolomite, 7 parts wollastonite, 5 parts kaolinite for glaze, 8 parts calcined alumina, 3 parts barium carbonate, 5 parts calcined talc, 14 parts Jiangxi lithium porcelain stone, 3 parts high zinc emulsion frit powder, 6 parts cobalt black material and 2 parts cobalt blue material.

[0070] The sanitary ware obtained in Examples 1-4 and Comparative Example 1 was glazed with black matte glaze on the pretreated sanitary ware blanks. The glazing was carried out by spraying, with a glaze thickness of 1 mm, a spraying pressure of 0.4 MPa, and a spraying flow rate of 560 ml / 30 sec. Subsequently, the sanitary ware was fired. The firing temperature curve included: (1) from room temperature to 480°C, taking 180 min; (2) from 480°C to 990°C, taking 200 min; (3) from 990°C to 1210°C, taking 220 min; (4) holding at 1210°C for 30 min; (5) from 1210°C to 1100°C, taking 60 min; (6) from 1100°C to 680°C, taking 30 min; (7) from 680°C to room temperature, taking 240 min. After cooling, a matte black sanitary ware porcelain product was obtained.

[0071] The performance of the matte black sanitary ware prepared in Examples 1-4 and Comparative Example 1 was tested, as shown in Table 2.

[0072] Table 2 - Performance Test Results

[0073]

[0074] By observing the appearance of the matte black sanitary ware in Examples 1-4, it can be seen that the ratio between cobalt black material and cobalt blue material can be adjusted according to actual needs, thereby adjusting the required color.

[0075] By comparing the appearance of the matte black sanitary ware in Examples 1 and 4, it can be seen that: increasing the amount of barium carbonate reduces the gloss of the glaze and makes the glaze matte; adding Jiangxi lithium porcelain stone makes the glaze finer, with little change in gloss, and increases the high-temperature fluidity of the glaze; increasing the amount of zinc oxide significantly increases the crystallization of the glaze, making the glaze matte and coarser; reducing the amount of frit results in insufficient melting of the glaze, making it rough and causing a small number of pinholes.

[0076] By comparing Example 1 and Comparative Example 1, when the silicon content is reduced and the aluminum content is increased, the ratio of Al2O3 to SiO2 is 1:(3-4), which is conducive to the precipitation and growth of mullite, anorthite, and other crystals. However, the glaze surface is prone to over-crystallization. The increased Al2O3 content makes the glaze viscosity higher at high temperatures, making it difficult for gas to escape, causing bubbles on the glaze surface. Melting occurs at the edges of the bubbles, which easily leads to pinholes and crystal spots. Mullite crystals and crystal spots are not conducive to the development of black pigment. The location of the crystal spots is grayish, while the location of the spots is black. The glaze surface has a layer of gray haze, resulting in a hazy and rough glaze surface.

[0077] During the above glazing process, the black matte glaze for sanitary ware with a high amount of Jiangxi lithium porcelain stone has greater fluidity than the black matte glaze for sanitary ware with a low amount of Jiangxi lithium porcelain stone.

[0078] 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 equivalent variations or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A black matte glaze for sanitary ware, characterized in that, The product includes a base glaze and a cobalt-containing colorant. By weight, the base glaze comprises the following components: 8-15 parts potassium feldspar, 25-36 parts quartz powder, 1-2 parts calcined zinc oxide, 12-15 parts dolomite, 7-9 parts wollastonite, 3-5 parts kaolinite for glaze, 1-3 parts calcined alumina, 2-8 parts barium carbonate, 4-7 parts calcined talc, and 10-17 parts Jiangxi lithium porcelain stone. By weight, the cobalt-containing colorant comprises 6-11 parts. The chemical composition of the base glaze, by mass percentage, includes 62.00–63.00% SiO2, 7.60–8.60% Al2O3, 0.10–0.50% Fe2O3, 0.01–0.05% TiO2, 8.25–9.25% CaO, 4.25–5.15% MgO, 1.50–1.95% K2O, 1.05–1.55% Na2O, 0.20–0.60% Li2O, 0.00–0.05% ZrO2, 0.90–1.60% ZnO, 0.01–0.40% B2O3, 2.10–5.50% BaO, and 7.80–8.85% loss on ignition.

2. The black matte glaze for sanitary ware according to claim 1, characterized in that, The cobalt-containing colorant includes 5 to 8 parts of cobalt black and 1 to 3 parts of cobalt blue.

3. The black matte glaze for sanitary ware according to claim 1, characterized in that, It also includes 0 to 3 parts of high-zinc emulsion frit powder.

4. The black matte glaze for sanitary ware according to claim 1, characterized in that, The ratio of Al2O3 to SiO2 in the black matte glaze for sanitary ware is 1:(6-9).

5. The black matte glaze for sanitary ware according to claim 1, characterized in that, The particle size of the black matte glaze used in the sanitary ware is 1–25 μm.

6. A matte black sanitary ware, characterized in that, The surface of the sanitary ware is provided with a matte black glaze layer; the glaze layer is fired with the black matte glaze of any one of claims 1 to 5.

7. A matte black sanitary ware according to claim 6, characterized in that, The raw material of the sanitary ware includes either porcelain or stoneware.

8. A method for preparing a matte black sanitary ware, characterized in that, The process includes the following steps: applying a black matte glaze, as described in any one of claims 1 to 5, to the raw ceramic sanitary ware body, and firing it to obtain a matte black sanitary ware ceramic product.

9. The method for preparing a matte black sanitary ware according to claim 8, characterized in that, The firing temperature profile includes: (1) It took 180 minutes to heat the temperature from room temperature to 480℃; (2) It took 200 minutes to heat the temperature from 480℃ to 990℃; (3) It took 220 minutes to raise the temperature from 990℃ to 1210℃; (4) Keep warm at 1210℃ for 30 minutes; (5) The temperature dropped from 1210℃ to 1100℃ in 60 minutes; (6) The temperature dropped from 1100℃ to 680℃ in 30 minutes; (7) It took 240 minutes to cool from 680℃ to room temperature.

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