Ceramic with excellent appearance and stain resistance

Abstract

To provide a pottery having improved beauty and including a glaze layer capable of inhibiting attachment of fine stain to a surface thereof.SOLUTION: In a pottery including at least a bare surface and a glaze layer, a dielectric constant, a dielectric dissipation factor tan δ, or surface resistivity of a surface of the glaze layer is controlled. This pottery has improved beauty and is configured to inhibit attachment of fine stain to a surface thereof.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to pottery having a glaze layer, and more particularly to pottery having excellent appearance and stain resistance. [Background technology]

[0002] Recently, ceramics such as sanitary ware and tiles are required to have a high level of aesthetic appeal due to the growing demand for aesthetic spaces. Furthermore, with changes in the way toilet spaces are used, such as the use of smartphones, there are more opportunities for ceramic surfaces to be scratched, such as heavy objects being dropped on them.

[0003] Sanitary ware and ceramics used in bathrooms and other areas are expected to have superior hygiene properties, such as being less susceptible to stains and being easier to remove once stains have formed. Furthermore, with increased awareness of hygiene and the COVID-19 pandemic, attention is being drawn to the issue of invisible stains on ceramic surfaces.

[0004] To prevent stains from adhering to the glaze surface of pottery or to facilitate the removal of stains that do adhere, the smoothness of the glaze surface is generally controlled to a high level. However, the physical shape of the glaze surface alone may not be enough to prevent adhesion. For example, in the case of viruses or fine stains, smoothing the surface does not effectively prevent their adhesion, nor does it necessarily make their removal easier.

[0005] Proposals for controlling the electrical properties of pottery surfaces include, for example, Japanese Patent Application Laid-Open No. 2001-123278 (Patent Document 1), which proposes improving the zeta potential and antibacterial properties of the glaze layer surface. Japanese Patent Application Laid-Open No. 9-63379 (Patent Document 2) also discloses controlling the dielectric constant of ceramic sand and the relative dielectric constant of the glaze layer, with the objective of improving the dielectric breakdown strength of suspension insulators (insulating devices). Japanese Patent Application Laid-Open No. 9-328380 (Patent Document 3) also discloses a glazing method in which the amount of glaze applied to the base is adjusted while measuring the glaze concentration based on electrical conductivity, but does not mention the properties of the finished glaze layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-123278 [Patent Document 2] Japanese Patent Application Publication No. 9-63379 [Patent Document 3] Japanese Patent Application Publication No. 9-328380 Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors have now discovered that controlling the electrical properties of the surface of a ceramic glaze layer can improve the appearance of the ceramic and prevent the adhesion of fine stains to the surface. Furthermore, the electrical properties of the glaze layer can be efficiently controlled by appropriately managing manufacturing conditions such as the preparation of the glaze ingredients and the conditions for applying them to the ceramic body. The present invention is based on this discovery.

[0008] Therefore, an object of the present invention is to provide ceramics that are excellent in appearance and stain resistance. [Means for solving the problem]

[0009] According to a first aspect, the pottery of the present invention is pottery comprising at least a pottery body and a glaze layer, and is characterized in that the relative dielectric constant of the surface of the glaze layer is greater than 5.5 and less than 6.0.

[0010] According to a second aspect, the pottery of the present invention comprises at least a pottery body and a glaze layer, and is characterized in that the dielectric tangent tanδ of the surface of the glaze layer is 0.0040 or more and 0.0065 or less.

[0011] According to a third aspect of the present invention, the pottery comprises at least a pottery body and a glaze layer, and the surface resistivity of the surface of the glaze layer is 4.0 × 10 14 Ω or more 8.0×10 14 It is characterized in that the resistance is Ω or less. [Effects of the Invention]

[0012] The ceramic according to the present invention can improve the appearance and also prevent the adhesion of fine dirt to the surface. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of a glaze sample with electrodes attached for measuring the relative dielectric constant of the glaze layer. [Figure 2] FIG. 1 is a schematic diagram of a glaze sample with electrodes attached for measuring the surface resistivity of the glaze layer. [Figure 3] 1 is an image taken with a digital microscope of the surface of the glaze layer of Example 1 after acetylene carbon black was attached to the glaze layer and the glaze layer was left standing in an atmosphere with a wind speed of 1.0 m / s for 30 minutes. [Figure 4] 1 is an image of the surface of the glaze layer of Comparative Example 1 photographed with a digital microscope after an experiment in which acetylene carbon black was attached to the glaze layer under the same conditions as in Example 1 above. DETAILED DESCRIPTION OF THE INVENTION

[0014] Pottery In this invention, "ceramics" refers to sanitary ware, tiles, and other items that have a basic structure of a ceramic base coated with a glaze layer. Also, "sanitary ware" refers to ceramic products used in bathrooms, toilet spaces, dressing rooms, washrooms, kitchens, etc. Specifically, it refers to toilet bowls, urinals, toilet sinks, toilet tanks, washbasins, hand basins, etc.

[0015] glaze

[0016] In the present invention, the glaze may be a mixture of natural mineral particles such as silica sand, feldspar, or limestone, and / or an amorphous glaze containing an opacifier and further containing a pigment. Examples of opacifiers include zircon and tin oxide. The glaze may have a composition of, for example, 52 to 80 parts by weight of SiO2, 5 to 14 parts by weight of Al2O3, 6 to 17 parts by weight of CaO, 0.5 to 4.0 parts by weight of MgO, 0.1 to 11 parts by weight of ZnO, 1 to 5 parts by weight of KO, 0.5 to 2.5 parts by weight of Na2O, 0.1 to 15 parts by weight of opacifier, and 0.001 to 20 parts by weight of pigment. The glaze may also contain other additives such as a sizing agent, a dispersant, a preservative, and an antibacterial agent. Examples of pigments include cobalt compounds and iron compounds. The amorphous glaze is a glaze obtained by melting a glaze raw material consisting of a mixture of natural mineral particles and the like at a high temperature and vitrifying it, and for example, a frit glaze can be suitably used.

[0017] First aspect of the present invention The ceramic according to the first aspect of the present invention has a surface dielectric constant of the glaze layer exceeding 5.5 and less than 6.0. This glaze layer provides the ceramic with excellent aesthetics and reduces the adhesion of fine stains to its surface. Here, "fine stains" refers to particles whose size cannot be effectively or easily prevented by the physical shape of the glaze layer surface alone, e.g., particles of about 300 nm, down to the virus level. The ceramic according to the present invention has excellent aesthetics, particularly improved luster and color, and also has the properties of preventing the adhesion of fine stains or easily removing fine stains that have already adhered. Therefore, for example, by applying the ceramic to the entire surface of the ceramic, which is visible to users or is particularly likely to accumulate dirt, a beautiful, stain-resistant sanitary ceramic, including toilets and urinals, can be obtained.

[0018] The dielectric constant of a ceramic glaze layer can be measured in accordance with JIS C2138. Specifically, the measurement is performed as follows. First, a ceramic test piece with a glazed surface is prepared. The test piece may be prepared for testing under the same conditions as the finished product, with the same glaze composition, base composition, and firing temperature. Alternatively, the test piece may be cut from the finished ceramic with the surface intact. The thickness of the test piece is 1 mm. This test piece may be 1 mm, including the glaze layer and base. Next, as shown in Figure 1, a main electrode 11 and a counter electrode 12 are attached to the test piece 10. The main electrode 11 and the counter electrode 12 are circular electrodes without guard rings, and the main electrode 11 and the counter electrode 12 have different diameters. The thickness a of the main electrode 11 is sufficiently smaller than the thickness h of the test piece. The main electrode 11 and the counter electrode 12 are made of Ag, and an Ag layer is formed using Ag paste or ion sputtering. Then, the capacitance between the electrodes of the test piece is measured using an impedance analyzer, and the relative dielectric constant is calculated using the following formula: Measurement conditions are in the air, at room temperature, and at a frequency of 1 MHz.

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[0019] Furthermore, according to a first aspect of the present invention, there is provided a method for evaluating the surface aesthetics or stain resistance of pottery, which method is characterized by preparing pottery with a glaze layer and measuring and calculating the relative dielectric constant of the surface of the glaze layer, and preferably includes a step of evaluating the pottery as having excellent surface aesthetics or stain resistance when the relative dielectric constant of the surface of the glaze layer is greater than 5.5 and less than 6.0.The method of the present invention is not limited to the evaluation of actual pottery, and can, for example, be used to prepare test pieces and measure their electrical properties to evaluate the surface aesthetics or stain resistance of final products, which has the advantage of allowing for efficient setting of glaze composition, firing conditions, etc., and improving manufacturing efficiency.

[0020] Second Aspect of the Invention In the ceramic according to the second aspect of the present invention, the dielectric loss tangent tanδ of the surface of the glaze layer is 0.0040 or more and 0.0065 or less. By using such a glaze layer, the ceramic has excellent aesthetic appeal and can suppress the adhesion of fine stains to its surface. Here, "fine stains" refers to particles of a size that cannot be effectively or easily prevented by the physical shape of the glaze layer surface alone, e.g., particles of about 300 nm, down to the virus level. The ceramic according to the present invention has excellent aesthetic appeal, particularly improved gloss and color, and also has the properties of preventing the adhesion of fine stains or easily removing fine stains that have already adhered. Therefore, for example, by using the ceramic in the entire area visible to users or areas that are particularly prone to soil adhesion, a sanitary ceramic, including toilets and urinals, can be obtained that is excellent in aesthetic appeal and stain-resistant.

[0021] The dielectric loss tangent (tanδ) of the ceramic glaze layer can be measured in accordance with JIS C2141. Specifically, a test piece is prepared, electrodes are formed on it, and the impedance is measured using an impedance analyzer, as in the first embodiment. The test piece may be prepared for testing under the same conditions as the finished product, with the same glaze and base compositions and firing temperatures. Alternatively, the test piece may be cut from the finished ceramic with the surface intact. The test piece thickness is 1 mm. This test piece may be 1 mm thick, including the glaze layer and base. Next, as shown in Figure 1, a main electrode 11 and a counter electrode 12 are attached to the test piece 10. The main electrode 11 and the counter electrode 12 are circular electrodes without guard rings, with different diameters, and the thickness (a) of the main electrode 11 is sufficiently smaller than the thickness (h) of the test piece. The main electrode 11 and the counter electrode 12 are made of Ag, and the Ag layer is formed using Ag paste or ion sputtering. The dielectric loss tangent (tanδ) is then measured using an impedance analyzer under the following measurement conditions: in air, at room temperature, and at a frequency of 1 MHz.

[0022] Furthermore, according to a second aspect of the present invention, there is provided a method for evaluating the surface aesthetics or stain resistance of pottery, which method comprises preparing pottery with a glaze layer and measuring and calculating the dielectric loss tangent tanδ of the surface of the glaze layer, and preferably includes a step of evaluating the pottery as having excellent surface aesthetics or stain resistance when the relative dielectric constant of the surface of the glaze layer is between 0.0040 and 0.0065. The method of the present invention is not limited to the evaluation of actual pottery; for example, by preparing a test piece and measuring its electrical properties, it is possible to evaluate the surface aesthetics or stain resistance of the final product, which has the advantage of allowing for efficient setting of the glaze composition, firing conditions, etc., and improving production efficiency.

[0023] Third aspect of the present invention The ceramic according to the third aspect of the present invention has a surface resistivity of the surface of the glaze layer of 4.0×10 14 Ω or more 8.0×10 14The resistance of the ceramic is Ω or less. By using such a glaze layer, the ceramic has excellent aesthetic appeal and can suppress the adhesion of fine stains to its surface. Here, "fine stains" refers to particle sizes that cannot be effectively or easily prevented by the physical shape of the glaze layer surface alone, such as those on the order of 300 nm, which is the virus level. The ceramic according to the present invention has excellent aesthetic appeal, particularly improved gloss and color, and also has the property of preventing the adhesion of fine stains or easily removing fine stains that have already adhered. Therefore, for example, by using the ceramic according to the present invention on the entire surface of the area visible to the user, or on areas that are particularly prone to soiling, it is possible to obtain sanitary ceramics, including toilets and urinals, that have excellent aesthetic appeal and are stain-resistant.

[0024] The surface resistivity of a ceramic glaze layer can be measured in accordance with JIS C2141. Specifically, it is measured by the following method. First, a ceramic test piece with a glazed surface is prepared. The test piece may be prepared for testing under the same conditions as the finished product, with the same glaze composition, base composition, and firing temperature. Alternatively, the test piece may be cut from the finished ceramic while maintaining the surface. The thickness of the test piece is 1 mm. This test piece may be 1 mm including the glaze layer and base. Next, as shown in Figure 2, a main electrode 21, a guard electrode 22, and a counter electrode 23 are attached to the test piece 20. These electrodes are made of Ag, and the Ag layer is formed by Ag paste or ion sputtering. A DC voltage V (V) is applied to the test piece, and the current I (mA) is measured after charging for 1 minute to determine the surface resistance R of the test piece. S The surface resistivity ρ is calculated by measuring the surface resistivity ρ in the air at room temperature with an applied voltage of 1000V.

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[0025] Furthermore, according to a third aspect of the present invention, there is provided a method for evaluating the surface aesthetics or stain resistance of pottery, which method comprises preparing pottery with a glaze layer and measuring and calculating the surface resistivity of the glaze layer surface, and preferably includes a step of evaluating the pottery as having excellent surface aesthetics or stain resistance when the relative dielectric constant of the glaze layer surface is 4.0 or more and 8.0 or less. The method of the present invention is not limited to the evaluation of actual pottery, and can also be used to evaluate the surface aesthetics or stain resistance of final products by, for example, preparing test pieces and measuring their electrical properties, which has the advantage of allowing for efficient setting of glaze composition, firing conditions, etc., and improving manufacturing efficiency.

[0026] Favorable properties of the glaze layer The surface of the glaze layer on the pottery according to the present invention preferably has the following L*a*b* values: L* is 81 or more and 94 or less, a* is -0.4 or more and -0.1 or less, and b* is 0.5 or more and 1.8 or less. By combining these with the various requirements of the present invention described above, the pottery will have excellent aesthetics, particularly good color appearance.

[0027] Ceramic base In the present invention, the pottery body may be prepared from any desired raw material, for example, by preparing a slurry from silica sand, feldspar, limestone, clay, etc., and then molding and firing the slurry.

[0028] According to a preferred embodiment of the present invention, the ceramic body has an overall chemical composition at the time of firing that includes 50-75 wt% SiO2, 17-40 wt% Al2O3, and 1-10 wt% K2O + Na2O. The ceramic body preferably contains 25-70 wt% glass phase and 75-30 wt% crystalline phase. The chemical composition of the main components constituting the glass phase is preferably 50-80 wt% SiO2, 10-40 wt% Al2O3, and 4-12 wt% K2O + Na2O, based on the entire glass phase being 100%. The mineral composition of the main components constituting the crystalline phase is preferably 0-60 wt% α-alumina, 0-20 wt% quartz, and 2-20 wt% mullite, based on the entire body being 100%. The mineral composition of the main components constituting the crystalline phase may be a base material (e.g., a vitreous sintered ceramic body) that does not contain α-alumina. It is preferred that the SiO2 / Al2O3 ratio in the substrate material is greater than 1.

[0029] Pottery manufacturing method Pottery according to the present invention may be produced by providing a pottery body, applying a glaze slurry thereto, and firing.

[0030] The glaze slurry can be obtained by pulverizing the glaze raw materials using a ball mill or the like so that the 50% particle size is preferably 10 μm or less, more preferably 5 μm or less. In the glaze slurry, the particle size of the quartz raw material, such as silica sand, can be controlled separately from the other glaze raw materials to prevent quartz from remaining on the glaze surface.

[0031] According to a preferred embodiment of the present invention, pottery that meets the above requirements can be efficiently manufactured by controlling the manufacturing conditions. First, the viscosity of the glaze slurry is set to 800 to 1200 mPa·s. This effectively prevents the precipitation and separation of the glaze slurry, and efficiently controls the electrical properties of the resulting glaze layer.

[0032] The application of the glaze slurry to the ceramic body is preferably carried out by spray coating under the following conditions: the temperature of the ceramic body is set to 25-35°C, and the glaze water penetration time is set to 25-35 minutes. Furthermore, it is important to adjust the temperature of the glaze slurry during glazing to 25-30°C, regardless of the room temperature. In other words, temperature control here means controlling the temperature so that it is not affected by ambient temperature fluctuations due to geographical or seasonal factors at the production site.

[0033] Furthermore, it is preferable that the drying process after applying the glaze slurry to the ceramic body be carried out under appropriate temperature control. For example, drying after application is carried out for at least two hours in an atmosphere adjusted to 25-30°C. The ceramic according to the present invention can be produced through sufficient water penetration and particle adhesion and fixation in the applied glaze.

[0034] The pottery according to the present invention may be produced by appropriately determining the firing conditions in consideration of the composition of the pottery body and the glaze. For example, after applying the glaze to the pottery body, the molded body may be sintered at a temperature of 800 to 1300°C to fix the glaze layer. [Example]

[0035] The present invention will be further illustrated by the following examples, but the present invention is not limited to these examples.

[0036] Pottery manufacturing Preparing the glaze Two kilograms of glaze raw materials consisting of the compositions of Examples 1 to 5 and Comparative Examples 1 to 4 in Table 1, 1 kilogram of water, and 4 kilograms of spherical stones were placed in a 6-liter ceramic pot and ground in a ball mill so that the particle size of the colored glaze slurry after grinding was measured using a laser diffraction particle size analyzer, with 65% of the particles being 10 μm or less and the 50% average particle size (D50) being approximately 6.0 μm. Glazes were obtained by ball milling the glazes for Examples 3 to 5 and Comparative Examples 1 and 3. Silica sand was separately ground in a ball mill to an average particle size of approximately 19 μm, and mixed with the other materials. The viscosity of all the resulting glazes was 800 to 1200 mPa·s.

[0037] [Table 1]

[0038] Applying glaze to pottery body The ceramic body was prepared by weighing 38-75 wt% sericite and kaolin pottery stone (skeleton-forming materials), 8-45 wt% china clay (powder) and ball clay (powder) (plastic materials), 8-20 wt% feldspar (primary sintering aid), and 1-4 wt% dolomite, with the main composition ranging from 50-75 wt% SiO2, 17-40 wt% Al2O3, and 1-10 wt% K2O + Na2O. Water and an appropriate amount of sodium silicate as a deflocculating agent were added, and the mixture was wet-ground in a ball mill to obtain a ceramic body material. The resulting ceramic body material was molded using a slip casting method using a plaster mold to obtain a green body, which was then fired in an electric furnace to obtain a ceramic body. The glazes from the above examples and comparative examples were then spray-coated onto the resulting material. Here, the pottery body was heated or cooled to a temperature of 25 to 35°C as needed, and the glaze temperature was also set to 25 to 35°C, and the glaze was spray coated at an ambient temperature of 25 to 35°C. After glazing, the pottery was left to stand for 2 hours or more in an atmosphere adjusted to 25 to 30°C, and then fired at 1100 to 1300°C for 2 to 25 hours to obtain pottery.

[0039] Calculating the relative permittivity The glazes of the above examples and comparative examples were applied to ceramic bases and fired under the same conditions as above to prepare glaze samples. These were then cut into disks approximately 1 mm thick and 20 mm in diameter to serve as samples for measuring the relative dielectric constant. In accordance with JIS C2138, electrodes were attached to these samples as shown in Figure 1, and the capacitance between the electrodes was measured using an impedance analyzer (Impedance Analyzer E4990A, Keysight Technologies). The dielectric loss tangent was calculated using equations (1) to (4) above. The measurement conditions were a frequency of 1 MHz, room temperature, and air, and the electrodes were formed by Ag sputtering. The results are shown in Table 2 below.

[0040] Measurement of dielectric tangent tanδ Using the sample prepared for measuring the relative permittivity, electrodes were attached as shown in Figure 1, and the dielectric loss tangent tanδ between the electrodes was measured using an impedance analyzer. The measurement conditions were a frequency of 1 MHz, room temperature, and air, and the electrodes were formed by sputtering Ag. The results are shown in Table 2 below.

[0041] Calculating surface resistivity Using a sample prepared for measuring the relative permittivity, electrodes were attached as shown in Figure 2 in accordance with JIS C2141. A direct voltage of 1000 V was applied to the sample, and the current after charging for 1 minute was measured using a resistivity meter to obtain the surface resistance Rs. During the measurement, dry air was flowed through the atmosphere at 300 cc / min. The surface resistivity ρ was calculated from the obtained surface resistance Rs using the above-mentioned equations (21) to (23). The results are shown in Table 2 below.

[0042] Evaluation of dirt adhesion prevention: residual particle amount (%) To tiles, 1.5g / cm 2After that, acetylene carbon black with a particle size of approximately 21 nm was attached to the sample under a load of 0.05g, and the sample was left to stand in an atmosphere with a wind speed of 1.0 m / s for 30 minutes. The surface was then photographed using a digital microscope, and the area ratio of the carbon black attached to the surface was calculated from the acquired images using image analysis software. Four images were taken for each sample, and the average area (%) calculated from the images was obtained. This was designated as the "amount of residual fine particles present." The results are shown in Table 2. Images of the surface photographed using a digital microscope for Example 1 and Comparative Example 1 are shown in Figures 3 and 4.

[0043] Physical property evaluation test Measurements of the L*a*b* color system were performed using a spectrophotometer to obtain the L*, a*, and b* values. The obtained L*, a*, and b* values ​​are shown in Table 2.

[0044] Color evaluation The appearance of the resulting pottery was visually evaluated as follows: the color compared with the standard color was scored on a 5-point scale. The results are shown in Table 2.

[0045] [Table 2]

[0046] Preferred embodiments of the present invention Preferred aspects of the present invention are as follows. Regarding the first aspect of the present invention, (1) Pottery comprising at least a base and a glaze layer, The sanitary ware, wherein the relative dielectric constant of the surface of the glaze layer is more than 5.5 and less than 6.0. (2) The pottery according to (1), wherein the L* of the surface of the glaze layer is 81 or more and 94 or less. (3) The pottery according to (1) or (2), wherein the a* of the surface of the glaze layer is -0.4 or more and -0.1 or less. (4) The pottery according to any one of (1) to (3), wherein the b* of the surface of the glaze layer is 0.5 or more and 1.8 or less. (5) The ceramic according to any one of (1) to (4), which is sanitary ceramic. (6) A method for evaluating the surface aesthetics or stain resistance of ceramics, comprising: Prepare pottery with a glaze layer, The method comprises a step of measuring and calculating the relative dielectric constant of the surface of the glaze layer. (7) The method according to (6), wherein the surface of the pottery is evaluated as having excellent aesthetics or stain resistance when the relative dielectric constant of the surface of the glaze layer is greater than 5.5 and less than 6.0.

[0047] Regarding the second aspect of the present invention, (1) Pottery comprising at least a base and a glaze layer, The sanitary ware, wherein the dielectric tangent tanδ of the surface of the glaze layer is 0.0040 or more and 0.0065 or less. (2) The pottery according to (1), wherein the L* of the surface of the glaze layer is 81 or more and 94 or less. (3) The pottery according to (1) or (2), wherein the a* of the surface of the glaze layer is -0.4 or more and -0.1 or less. (4) The pottery according to any one of (1) to (3), wherein the b* of the surface of the glaze layer is 0.5 or more and 1.8 or less. (5) The ceramic according to any one of (1) to (4), which is sanitary ceramic. (6) A method for evaluating the surface aesthetics or stain resistance of ceramics, comprising: Prepare pottery with a glaze layer, The method comprises a step of measuring and calculating the dielectric tangent tanδ of the surface of the glaze layer. (7) The method according to (6), wherein the ceramic surface is evaluated as having excellent aesthetics or stain resistance when the dielectric loss tangent tanδ of the surface of the glaze layer is 0.0040 or more and 0.0065 or less.

[0048] Regarding the third aspect of the present invention, (1) Pottery comprising at least a base and a glaze layer, The surface resistivity of the surface of the glaze layer is 4.0 × 10 14 Ω or more 8.0×10 14 Sanitary ware, below Ω. (2) The pottery according to (1), wherein the L* of the surface of the glaze layer is 81 or more and 94 or less. (3) The pottery according to (1) or (2), wherein the a* of the surface of the glaze layer is -0.4 or more and -0.1 or less. (4) The pottery according to any one of (1) to (3), wherein the b* of the surface of the glaze layer is 0.5 or more and 1.8 or less. (5) The ceramic according to claim 1 or 2, which is sanitary ceramic. (6) A method for evaluating the surface aesthetics or stain resistance of ceramics, comprising: Prepare pottery with a glaze layer, The method comprises a step of measuring and calculating the surface resistivity of the surface of the glaze layer. (7) The surface resistivity of the surface of the glaze layer is 4.0 × 10 14 Ω or more 8.0×10 14 If the resistance is Ω or less, the ceramic surface is evaluated as having excellent aesthetics or stain resistance.

Claims

1. Pottery comprising at least a base and a glaze layer containing zircon as an opacifying agent, The glaze composition of the glaze layer is SiO ２ 52 to 80 parts by weight of Al ２ O ３ 5 to 14 parts by weight, CaO 6 to 17 parts by weight, MgO 0.5 to 4.0 parts by weight, ZnO 0.1 to 11 parts by weight, K ２ 1 to 5 parts by weight of O, and Na ２ It contains at least 0.5 to 2.5 parts by weight of O, the relative dielectric constant of the surface of the glaze layer is 5.6 or more and 5.9 or less; The ceramic has a surface L* of 88 to 94, a* of -0.4 to -0.1, and b* of 0.5 to 1.

8.

2. The ceramic according to claim 1, which is sanitary ceramic.

3. A method for evaluating the surface aesthetics and stain resistance of ceramics, comprising: Prepare pottery with a glaze layer, measuring and calculating the relative dielectric constant of the surface of the glaze layer, The glaze layer contains zircon as an opacifier, and the glaze composition of the glaze layer contains at least 52 to 80 parts by weight of SiO 2 , 5 to 14 parts by weight of Al 2 O 3 , 6 to 17 parts by weight of CaO, 0.5 to 4.0 parts by weight of MgO, 0.1 to 11 parts by weight of ZnO, 1 to 5 parts by weight of K 2 O, and 0.5 to 2.5 parts by weight of Na 2 O; the L* of the surface of the glaze layer is 81 or more and 94 or less, the a* is -0.4 or more and -0.1 or less, and the b* is 0.5 or more and 1.8 or less, When the relative dielectric constant of the surface of the glaze layer is 5.6 or more and 5.9 or less, the surface of the pottery A method for evaluating a surface as having excellent aesthetics and stain resistance.

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