Ceramic with excellent appearance and stain resistance

Abstract

To provide earthenware that is excellent in appearance, is improved especially in glossiness and color development, and suppresses a damage of such an extent as not to influence on dirt adhesion from giving influence on the appearance.SOLUTION: Earthenware comprises at least a base material and a glaze layer, and three-dimensionally controls in the glaze layer, an emulsifier and the existence of silica sand in the layer. The earthenware is improved in appearance, and especially glossiness and color development, and suppresses a damage of such an extent as not to influence on dirt adhesion from giving influence on the appearance.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to pottery having a glaze layer, and more particularly to beautiful pottery. [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] The glaze layer is made opaque by using an opacifying agent, and various efforts have been made to control the opacifying agent to improve the appearance of the pottery, and to control the surface irregularities to prevent the adhesion of dirt or to make it easier to remove dirt (for example, JP 2003-238274 A (Patent Document 1), JP 2002-316885 A (Patent Document 2)). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-238274 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-316885 Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors have now discovered that by three-dimensionally controlling the presence of opacifiers and silica sand in the glaze layer, the aesthetic appearance of the pottery, particularly its gloss and color, can be improved, and even scratches that do not affect the adhesion of dirt can be suppressed from affecting the aesthetic appearance, resulting in excellent stain resistance. Furthermore, three-dimensional control of the opacifiers and silica sand in the glaze layer can be efficiently achieved by appropriately managing manufacturing conditions such as the preparation of the glaze ingredients and the conditions for applying them to the pottery body. The present invention is based on these findings.

[0006] Therefore, an object of the present invention is to provide ceramics that are excellent in appearance and stain resistance. [Means for solving the problem]

[0007] 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 opacifying agent hiding rate on the surface of the glaze layer is 0.45% or more and 22.1% or less.

[0008] According to a second aspect, the pottery of the present invention is pottery comprising at least a pottery body and a glaze layer, characterized in that the amount of opacifying agent on the surface of the glaze layer is 5 μm or more and 25 μm or less.

[0009] According to a third aspect of the present invention, the pottery comprises at least a pottery body and a glaze layer, and is characterized in that the opacifier and silica sand hiding rate on the surface of the glaze layer is 4% or more and 24% or less.

[0010] According to a fourth aspect, the pottery of the present invention is pottery comprising at least a pottery body and a glaze layer, characterized in that the opacifier and silica sand hiding amount on the surface of the glaze layer is 14 μm or more and 41 μm or less.

[0011] According to a fifth aspect, the pottery of the present invention is pottery comprising at least a pottery body and a glaze layer, characterized in that the surface of the glaze layer has a du value of 32 or more and 55 or less as measured by a Wavescan DOI measuring device. [Effects of the Invention]

[0012] The ceramic ware according to the present invention has excellent aesthetic appearance, particularly improved gloss and color development, and even scratches that do not affect the adhesion of dirt have little effect on the aesthetic appearance. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an explanatory diagram of (1) the glaze layer surface, (2) a cross section of the surface portion of the glaze layer, (3) a cross section of the center portion of the glaze layer, and (4) a cross section of the interface portion of the glaze layer in the present invention. In the diagram, the glaze layer 1 is provided on a base 2, and the surface 11 of the glaze layer 1 is called (1) the glaze layer surface. The glaze layer 1 is further divided into three equal parts in the thickness direction, and the cross sections 12, 13, and 14 obtained by cutting the glaze layer in the vertical direction (along the dotted lines in the diagram) are called (2) the cross section of the surface portion of the glaze layer, (3) the cross section of the center portion of the glaze layer, and (4) the cross section of the interface portion of the glaze layer. [Figure 2] 1 is an SEM image of the surface of the glaze layer (1) of Example 1. In the image, areas 21 that appear whiter than the surrounding area are opacifiers (zircon), and areas 22 that appear darker than the surrounding area are silica sand. 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 The glaze for forming the glaze layer of the pottery according to the present invention is not particularly limited, and various glazes can be used as long as they contain an opacifying agent.

[0016] For example, the glaze used in the present invention may be a mixture of natural mineral particles such as silica sand, feldspar, and limestone, and / or an amorphous glaze containing an opacifier and further containing a pigment. Examples of opacifiers include zircon and tin oxide. The glaze composition may be, 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, 3 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] Opacifier hiding rate (%) As used herein, "opacifier hiding ratio (%)" refers to the volumetric ratio of opacifier, particularly zircon (ZrSiO4), observed in the glaze layer. Preferably, SEM observation allows electrons to penetrate to a certain depth, allowing the amount of opacifier present not only at the surface but also at a certain depth to be determined as a volume fraction. This volume fraction is referred to herein as the opacifier hiding ratio (%). Opacifiers in the glaze layer can be recognized in SEM images with a contrast different from that of other components. Furthermore, SEM can be used to determine the volume fraction of opacifier present not only at the surface but also at a certain depth, both in the form of primary particles and in the form of aggregated particles. Since the size of aggregated particles differs from that of primary particles, the effect of the opacifier changes. Therefore, the "opacifier hiding ratio," which captures the opacifier as both primary particles and aggregated particles, is an index that more accurately reflects the effect of the opacifier and is advantageous for three-dimensional control.

[0018] Furthermore, the opacifying rate of the glaze layer is observed at the following four locations: (1) the glaze layer surface, (2) a cross section of the surface layer of the glaze layer, (3) a cross section of the center of the glaze layer, and (4) a cross section of the interface of the glaze layer. Here, (1) the glaze layer surface refers to the observation from the surface of the glaze layer of the pottery. On the other hand, (2) a cross section of the surface layer of the glaze layer, (3) a cross section of the center of the glaze layer, and (4) a cross section of the interface of the glaze layer refer to cross sections obtained by cutting the glaze layer into three equal parts from the surface to the interface with the pottery body, and cutting each of these glaze layers approximately vertically. 1 is a cross-sectional view of pottery in which a glaze layer 1 is provided on a base 2, and (1) the glaze layer surface in the figure refers to the surface 11 of the glaze layer 1, and (2) the cross-section of the glaze layer surface, (3) the cross-section of the glaze layer center, and (4) the cross-section of the glaze layer interface in the figure refer to cross-sections 12, 13, and 14 obtained by dividing the glaze layer 1 into three equal parts in the thickness direction and then cutting it perpendicularly to the surface 11 (at the dotted lines in the figure). Note that in this specification, other measurements referred to as (1) the glaze layer surface, (2) the cross-section of the glaze layer surface, (3) the cross-section of the glaze layer center, and (4) the cross-section of the glaze layer interface have the same meaning.

[0019] Opacifier hiding amount (μm) As used herein, "opacifier hiding amount (μm)" refers to the ratio (area ratio) of opacifier, particularly zircon (ZrSiO4), observed on the surface of the glaze layer. The area occupied by the opacifier can be determined from SEM images. This area is approximated as a circle, and the average diameter is calculated. This value is referred to herein as the "opacifier hiding amount (μm)." Therefore, in this embodiment, "opacifier hiding amount (μm)" is understood as an index for grasping the three-dimensional presence of the opacifier in the glaze layer based on the area of its projected shape. The opacifier can be recognized in SEM images as a contrast different from other components in the glaze layer. Furthermore, SEM allows the volume fraction of opacifier present not only on the surface but also in a certain depth region, both in the form of primary particles and in the form of aggregated particles. When the size of the emulsion differs from that of the primary particles due to the form of aggregated particles, the effect of the presence of the opacifier also changes. Therefore, the "emulsion hiding amount," which grasps the emulsion not only as primary particles but also as aggregated particles, is an index that more accurately reflects the effect of the emulsifier and is advantageous for three-dimensional control.

[0020] Opacifier and silica sand hiding rate (%) As used herein, the term "opacifier and silica sand hiding ratio" refers to the volume ratio of opacifier, particularly zircon (ZrSiO4), to opacifier and silica sand observed in the glaze layer. Preferably, SEM observation allows electrons to penetrate to a certain depth, and the amount of opacifier and silica sand present in a certain depth region can be determined as a volume ratio. This volume ratio is referred to as the opacifier and silica sand hiding ratio (%) in this specification. The opacifier and silica sand can be recognized in SEM images with different contrast from other components in the glaze layer. Furthermore, SEM allows the volume ratio of opacifier and silica sand present not only on the surface but also in a certain depth region, both in the form of primary particles and in the form of aggregated particles. When the size of the opacifier and silica sand differs from that of the primary particles due to the form of agglomerated particles, the effect of the presence of the opacifier and silica sand also changes. Therefore, the "opacifier and silica sand hiding rate," which grasps the opacifier and silica sand not only as primary particles but also as agglomerated particles, is an index that more accurately reflects the effect of the opacifier and is advantageous for three-dimensional control.

[0021] Opacifier and silica sand hiding amount (μm) As used herein, "opacifier and silica sand hiding amount (μm)" refers to the ratio (area ratio) of opacifier and silica sand observed on the surface of the glaze layer. The area occupied by the opacifier and silica sand can be determined, preferably, from SEM images. This area is approximated as a circle, and the average diameter is calculated. This value is referred to herein as the "opacifier and silica sand hiding amount (μm)." Therefore, in this embodiment, "opacifier and silica sand hiding amount (μm)" is understood as an index for grasping the three-dimensional presence of the opacifier and silica sand in the glaze layer through the area of the projected shape. The opacifier and silica sand can be recognized in SEM images with different contrast from other components in the glaze layer. Furthermore, SEM allows the volume fraction of the opacifier and silica sand present not only on the surface but also in a certain depth region, both in the form of primary particles and in the form of agglomerates. If the size of the opacifier and silica sand differs from that of the primary particles due to their agglomerated particle form, the effect of the presence of the opacifier and silica sand will also change. Therefore, the "opacifier and silica sand hiding amount (μm)," which grasps the opacifier and silica sand not only as primary particles but also as agglomerated particles, is an index that more accurately reflects the effect of the opacifier and is advantageous for three-dimensional control.

[0022] du value measured by Wavescan DOI measuring device The DOI and du values measured by the Wave-Scan DOI measurement device used in this specification specifically refer to the DOI and du values measured by a Wave-Scan DIO (orange peel measurement device) manufactured by BYK Gardner (Germany). This device is known as a method for optically measuring the light / dark wavelength pattern of a target surface, similar to how the human eye does. In this microwave scan, a laser point source irradiates the sample surface with laser light at an angle of 60° from the perpendicular, and a detector measures the reflected light at the same angle but opposite to the perpendicular. This device moves the laser point source over the surface of the painted sample to scan, measuring the light / darkness of the reflected light point by point at set intervals, thereby detecting the optical profile of the sample surface. The detected optical profile can be spectrally analyzed through a frequency filter to analyze the base, interior, and surface structure of a painted surface, etc. The characteristic spectrum of this device is as follows: du: Wavelength 0.1mm or less Wa: Wavelength 0.1~0.3mm Wb: Wavelength 0.3~1mm Wc: Wavelength 1~3mm Wd: Wavelength 3~10mm We: Wavelength 10~30mm Sw: Wavelength 0.3~1.2mm Lw: Wavelength 1.2~12mm DOI: Wavelength 0.3mm or less Here, DOI is a parameter consisting of du, Wa, and Wb. DOI=f(du,Wa,Wb) In the present invention, the above du value is used.

[0023] First aspect of the present invention In the pottery according to the first aspect of the present invention, the glaze layer contains an opacifier, and the opacifier hiding rate on the surface of this glaze layer is 0.45% to 22.1%, preferably 15% or more. By using such a glaze layer, the pottery has an excellent appearance, especially improved gloss and color, and scratches that do not affect the adhesion of dirt do not have an adverse effect on the appearance.

[0024] The first aspect of the present invention preferably has any or all of the following (a) to (c): (a) the opacifying agent hiding rate of the cross section of the surface layer of the glaze layer is 4.0% to 20%, (b) the opacifying agent hiding rate of the cross section of the center part of the glaze layer is 3.5% to 16%, or (c) the opacifying agent hiding rate of the cross section of the glaze layer at the interface with the base material is 3.0% to 11%. By setting the opacifying agent hiding rate in the glaze layer in this manner, a more desirable ceramic appearance can be obtained.

[0025] In the first embodiment of the present invention, the opacifier hiding rate of the cross-sectional surface layer portion is preferably greater than that of the cross-sectional substrate boundary portion.

[0026] Furthermore, according to a first aspect of the present invention, there is provided a method for evaluating the aesthetic appearance of ceramic surfaces, which method comprises preparing ceramics having a glaze layer containing an opacifier, and measuring and calculating the opacifier hiding rate on the surface of the glaze layer, and preferably includes a step of evaluating the appearance of the ceramics as being excellent in aesthetic appearance when the opacifier hiding rate on the surface of the glaze layer is 0.45% or more and 22.1% or less.

[0027] Second Aspect of the Invention In the pottery according to the second aspect of the present invention, the glaze layer contains an opacifier, and the amount of opacifier hiding on the surface of this glaze layer is 5 μm to 25 μm, preferably 15 μm or less. By using such a glaze layer, the pottery has excellent appearance, especially improved gloss and color, and even scratches that do not affect the adhesion of dirt are less likely to affect the appearance.

[0028] The second aspect of the present invention preferably has any or all of the following (a) to (c): (a) the opacifying agent amount in the cross section of the surface layer of the glaze layer is 5 μm to 15 μm, (b) the opacifying agent amount in the cross section of the center of the glaze layer is 4 μm to 15 μm, or (c) the opacifying agent amount in the cross section of the glaze layer at the interface with the base material is 2 μm to 10 μm. By setting the opacifying agent amount in the glaze layer in this way, a more desirable ceramic appearance can be obtained.

[0029] Furthermore, according to a second aspect of the present invention, there is provided a method for evaluating the aesthetic appearance of the surface of pottery, which method is characterized by preparing pottery whose glaze layer contains an opacifier, and measuring and calculating the amount of opacifier hidden on the surface of the glaze layer, and preferably includes a step of evaluating the appearance of the pottery as being excellent in aesthetic appearance when the amount of opacifier hidden on the surface of the glaze layer is in the range of 5 μm or more and 25 μm or less.

[0030] Third aspect of the present invention In the pottery according to the third aspect of the present invention, the glaze layer contains an opacifier and silica sand, and the opacifier and silica sand hiding rate on the surface of this glaze layer is 4% to 24%. This type of glaze layer provides the pottery with excellent appearance, particularly improved gloss and color development, and minimizes the impact on the appearance even from scratches that do not affect the adhesion of dirt. It also provides excellent stain resistance.

[0031] The third aspect of the present invention preferably has any or all of the following (a) to (c): (a) the opacifying agent and silica sand hiding ratio in the cross section of the surface layer of the glaze layer is 3.0% to 17.5%, (b) the opacifying agent and silica sand hiding ratio in the cross section of the center of the glaze layer is 3.0% to 20%, or (c) the opacifying agent and silica sand hiding ratio in the cross section of the glaze layer at the interface with the substrate is 3.0% to 11%. By setting the opacifying agent and silica sand hiding ratio in the glaze layer in this way, a more desirable ceramic appearance can be obtained.

[0032] Furthermore, according to a third aspect of the present invention, there is provided a method for evaluating the aesthetic appearance of ceramic surfaces, which method comprises preparing ceramics having a glaze layer containing an opacifier, and measuring and calculating the opacifier and silica sand hiding rate on the surface of the glaze layer, and preferably includes a step of evaluating the appearance of the ceramics as being excellent in aesthetic appearance when the opacifier and silica sand hiding rate on the surface of the glaze layer is in the range of 4% or more and 24% or less.

[0033] Fourth aspect of the present invention In the pottery according to the fourth aspect of the present invention, the glaze layer contains an opacifier and silica sand, and the opacifier and silica sand hiding amount on the surface of the glaze layer is 14 μm to 41 μm. By using such a glaze layer, the pottery has excellent appearance, particularly improved gloss and color development, and even scratches that do not affect the adhesion of dirt are less likely to affect the appearance. Furthermore, the pottery also has excellent stain resistance.

[0034] The fourth aspect of the present invention preferably comprises any or all of the following (a) to (c): (a) the opacifying agent and silica sand hiding amount in the cross section of the surface layer of the glaze layer is 11 μm to 20 μm, (b) the opacifying agent and silica sand hiding amount in the cross section of the center of the glaze layer is 16 μm to 28 μm, or (c) the opacifying agent and silica sand hiding amount in the cross section of the glaze layer at the interface with the base material is 12 μm to 18 μm. By combining these opacifying agent ratios in the glaze layer, a more desirable ceramic appearance can be obtained.

[0035] In the fourth aspect of the present invention, the amount of opacifier and silica sand hidden in the cross-sectional surface layer portion is preferably greater than that in the cross-sectional substrate boundary portion.

[0036] Furthermore, according to a fourth aspect of the present invention, there is provided a method for evaluating the aesthetic appearance of the surface of pottery, which method is characterized by preparing pottery whose glaze layer contains an opacifier, and measuring and calculating the amount of opacifier and silica sand hiding on the surface of the glaze layer, and preferably includes a step of evaluating the appearance of the pottery as being excellent in aesthetic appearance when the amount of opacifier and silica sand hiding on the surface of the glaze layer is 14 μm or more and 41 μm or less.

[0037] Fifth aspect of the present invention In the pottery according to the fifth aspect of the present invention, the glaze layer contains an opacifier, and the surface of this glaze layer has a du value of 32 to 55 as measured by a Wavescan DOI measuring device. This type of glaze layer provides the pottery with excellent appearance, particularly improved gloss and color development, and minimizes the impact on the appearance even from scratches that do not affect the adhesion of dirt. It also provides excellent stain resistance.

[0038] Furthermore, according to a fifth aspect of the present invention, there is provided a method for evaluating the aesthetic appearance of the surface of pottery, which method is characterized by preparing pottery whose glaze layer contains an opacifier, and measuring the du value of the surface of the glaze layer, and preferably includes a step of evaluating the appearance of the pottery as being excellent in aesthetic appearance if the du value of the surface of the glaze layer is 32 or more and 55 or less.

[0039] Favorable properties of the glaze layer In a preferred embodiment, the glaze layer provided on the pottery according to the present invention has an L* of 84 or more on its surface. In a preferred embodiment, the pottery according to the present invention has a surface roughness Ra of 0.10 μm or less. Additionally, in a preferred embodiment, the pottery according to the present invention has a maximum surface height Ry of 0.25 μm or more and 0.50 μm or less. By combining these with the above-mentioned requirements of the present invention, the pottery has an excellent aesthetic appearance.

[0040] 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.

[0041] 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.

[0042] Pottery manufacturing method Pottery according to the present invention may be produced by providing a pottery body, applying a glaze slurry thereto, and firing.

[0043] Glaze slurry can be obtained by pulverizing glaze raw materials using a ball mill or the like, preferably to a particle size of 10 μm or less, more preferably 5 μm or less, in 50% of the glaze. In the glaze slurry, the particle size of quartz raw materials such as silica sand and opacifiers can be controlled separately from other glaze raw materials to control the amount of quartz and opacifiers remaining on the glaze surface.

[0044] According to a preferred embodiment of the present invention, pottery that meets the above requirements can be efficiently produced by controlling the manufacturing conditions. First, the viscosity of the glaze slurry is set to 800 to 1200 mPa·s. This effectively prevents the glaze slurry from settling or separating, and allows the morphology of the opacifier and silica sand in the resulting glaze layer to be controlled.

[0045] 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, which may vary depending on the geographical or seasonal factors of the production site. In other words, temperature control here means controlling the temperature so that it is not affected by the ambient temperature, which may vary depending on the geographical or seasonal factors of the production site.

[0046] 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.

[0047] 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]

[0048] The present invention will be further illustrated by the following examples, but the present invention is not limited to these examples.

[0049] The values in the following examples were measured and calculated by the following methods.

[0050] Measurement of opacifier hiding rate (%) The sample was cut into pieces approximately 3cm x 3cm in size and thoroughly washed. This sample was fixed to the sample stage of a Hitachi TM4000 tabletop low-vacuum scanning electron microscope and observed using SEM. The observation conditions were 500x magnification, 15kV accelerating voltage, approximately 12mm working distance, and BSE mode. Three locations on the zircon surface that were not extremely biased were selected and images were taken.

[0051] The captured images were analyzed using the image analysis software Winroof. Specifically, for example, Figure 2 is an SEM image of the glaze layer surface in Example 1 described below. The area ratio of zircon (21 in the figure), which appears white in the image, in the target region was calculated by automatic binarization. This area ratio was used as the opacifier hiding ratio. Note that obvious foreign matter, such as strips, which appears white in the image were excluded.

[0052] Measurement of opacifier hiding amount (μm) The sample was cut into pieces approximately 3cm x 3cm in size and thoroughly washed. This sample was fixed to the sample stage of a Hitachi TM4000 tabletop low-vacuum scanning electron microscope and observed using SEM. The observation conditions were 500x magnification, 15kV accelerating voltage, approximately 12mm working distance, and BSE mode. Three locations on the zircon surface that were not extremely biased were selected and images were taken.

[0053] The captured images were analyzed using the image analysis software Winroof. Specifically, for example, Figure 2 is an SEM image of the glaze layer surface in Example 1 described below. In this image, zircon (21 in the figure) that appears white in the target area was identified and automatically binarized. The area of the extracted opacifier particles was approximated to a circle, and the average diameter of the opacifier particles was calculated. This average diameter of the opacifier particles was used as the opacifier hiding amount (μm). Note that obvious foreign matter, such as strips that appear white, was excluded.

[0054] Measurement of opacifier and silica sand hiding rate (%) The sample was cut into pieces approximately 3cm x 3cm in size and thoroughly washed. This sample was fixed to the sample stage of a Hitachi TM4000 tabletop low-vacuum scanning electron microscope and observed using SEM. The observation conditions were 500x magnification, 15kV accelerating voltage, approximately 12mm working distance, and BSE mode. Three locations on the zircon surface that were not extremely biased were selected and images were taken.

[0055] The captured images were analyzed using the image analysis software Winroof. Specifically, for example, Figure 2 is an SEM image of the glaze layer surface in Example 1 described below. In this image, the area ratios of the zircon (21 in the figure), which appears white in the image, and the dark gray silica sand (22 in the figure) in the target region were calculated by automatic binarization. The threshold values for white and dark gray were set based on the normal glaze area in the image. This area ratio in the target region was defined as the opacifier and silica sand hiding rate (%). Note that obvious foreign matter, such as strips that appear white, was excluded.

[0056] Measurement of opacifier and silica sand hiding amount (μm) The sample was cut into pieces approximately 3cm x 3cm in size and thoroughly washed. This sample was fixed to the sample stage of a Hitachi TM4000 tabletop low-vacuum scanning electron microscope and observed using SEM. The observation conditions were 500x magnification, 15kV accelerating voltage, approximately 12mm working distance, and BSE mode. Three locations on the surface where there was no significant bias in the zircon and silica sand were selected and images were taken.

[0057] The captured images were analyzed using the image analysis software Winroof. Specifically, Figure 2 shows an SEM image of the glaze layer surface in Example 1 (described later). In the target area, the zircon (21 in the figure) that appears white and the dark gray silica sand (22 in the figure) were identified and automatically binarized. The areas of the extracted opacifying agent and silica sand particles were approximated to circles, and the average diameters of the opacifying agent and silica sand particles were calculated. The white and dark gray thresholds were set based on the normal glaze area in the image. This average value was used as the opacifying agent and silica sand concealment amount (μm). Note that obvious foreign matter, such as strips that appear white, was excluded.

[0058] Measurement of du value The sample was cut into a size of approximately 3 cm x 3 cm, thoroughly washed, and then the du value was measured using a Wavescan DOI measuring device.

[0059] Measurement of surface roughness Ra and maximum height Ry The surface roughness Ra and maximum height Ry of each sanitary ware were measured using a laser microscope in accordance with JIS B 0681-2: 2019. The measurement conditions were an S-filter of 0.00025 mm and an L-filter of 0.8 mm.

[0060] Pottery manufacturing Preparing the glaze 2 kg of glaze raw materials consisting of the compositions of Examples 1 to 4 and Comparative Examples 1 to 4 in Table 1, 1 kg of water, and 4 kg of spherical stones were placed in a 6-liter ceramic pot, and pulverized in a ball mill so that the particle size of the colored glaze slurry after pulverization measured using a laser diffraction particle size distribution analyzer would be 65% 10 μm or less and the 50% average particle size (D50) would be approximately 6.0 μm, yielding a glaze. The viscosity of the resulting glaze was 800 to 1200 mPa·s.

[0061] In Example 3, unlike the other Examples and Comparative Examples, the glaze materials excluding zircon were further pulverized in a ball mill so that 88% of the particles were 10 μm or less and the 50% average particle size (D50) was about 3.6 μm, and then mixed with zircon to obtain a glaze.

[0062] In Example 4 and Comparative Example 3, unlike the other Examples and Comparative Examples, silica sand was separately pulverized in a ball mill to an average particle size of about 10 μm and mixed with other materials to obtain a glaze.

[0063] In Comparative Example 4, unlike the other Examples and Comparative Examples, silica sand was separately pulverized in a ball mill to an average particle size of about 19 μm and mixed with other materials to obtain a glaze.

[0064] [Table 1]

[0065] 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 at least 2 hours in an atmosphere adjusted to 25 to 30°C, and then fired at approximately 1200°C for 18 hours to obtain pottery.

[0066] Physical property evaluation test The opacifier hiding rate (%), opacifier hiding amount (μm), opacifier and quartz sand hiding rate (%), opacifier and quartz sand hiding amount (μm), and du value measured by a Wavescan DOI measuring device were measured as described above. The results are shown in Table 2.

[0067] Color evaluation The appearance of the resulting sanitary ware was visually evaluated as follows: The color and gloss were compared to the standard color sample and scored out of 5 points, and the total score was used for evaluation. The results are shown in Table 2. Specifically, four technicians familiar with sanitary ware first scored the color and gloss of the ware compared to the standard sample, ranging from 5 points, meaning no difference at all, to 0 points, meaning a complete difference in color and gloss, and the evaluation was then averaged by the four technicians. A score of 9 or above was considered a pass.

[0068] Sliding test The ceramics of the examples and comparative examples were subjected to the following sliding test. That is, a household detergent containing an abrasive was applied to a household cleaning urethane sponge at 100 g / cm 2 The ceramic surface was rubbed 2000 times with a load of 1000.

[0069] After the test, the glaze layer surface was evaluated as follows: First, the surface roughness was measured using a laser microscope to measure the volume of the space in the protruding valleys, Vvv [ml / m 2 The protruding valley space (Vvv) on the surface of each sanitary ware was measured in accordance with JIS B 0681-2:2019. The area load ratio separating the core and protruding valley was set to 80%, and the measurement conditions were S-filter 0.00025 mm and L-filter 0.8 mm. The results are shown in Table 2 below.

[0070] After the test, the glaze surface was visually inspected and the scratches were evaluated as follows. Six technicians familiar with sanitary ware compared the ware before and after the sliding operation side by side, and the evaluation was based on how many of the six could sense no difference. The results are shown in Table 2 below.

[0071] [Table 2]

[0072] 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 glaze layer contains an opacifier, The sanitary ware has an opacifying agent hiding rate on the surface of the glaze layer of 0.45% or more and 22.1% or less. (2) The pottery according to (1), wherein the opacifying agent hiding rate of the cross section of the surface layer of the glaze layer is 4.0% or more and 20% or less. (3) The pottery according to (1) or (2), wherein the opacifying agent hiding rate of the central cross section of the glaze layer is 3.5% or more and 16% or less. (4) The pottery according to any one of (1) to (3), wherein the opacifier hiding rate of the cross section of the interface between the glaze layer and the base material is 3.0% or more and 11% or less. (5) The pottery according to any one of (1) to (4), wherein the opacifier hiding rate of the cross-sectional surface layer portion is greater than that of the cross-sectional body boundary portion. (6) The ceramic according to any one of (1) to (5), which is sanitary ceramic. (7) The ceramic according to any one of (1) to (6), whose surface has an L* of 84 or more. (8) The ceramic according to any one of (1) to (7), whose surface has a surface roughness Ra of 0.10 μm or less. (9) A method for evaluating the surface aesthetics of pottery, comprising: Prepare pottery with a glaze layer containing an opacifier. The method comprises a step of measuring and calculating the opacifier hiding rate on the surface of the glaze layer. (10) The method according to (9), wherein the appearance of the pottery is evaluated as being excellent in appearance when the opacifier hiding rate on the surface of the glaze layer is 0.45% or more and 22.1% or less.

[0073] Regarding the second aspect of the present invention, (1) Pottery comprising at least a base and a glaze layer, The glaze layer contains an opacifier, The pottery has an opacifying agent hiding amount on the surface of the glaze layer of 5 μm or more and 25 μm or less. (2) The pottery according to (1), wherein the opacifying agent hiding amount in the cross section of the surface layer of the glaze layer is 5 μm or more and 15 μm or less. (3) The pottery according to (1) or (2), wherein the amount of opacifier hiding in the central cross section of the glaze layer is 4 μm or more and 15 μm or less. (4) The pottery according to any one of (1) to (3), wherein the amount of opacifier concealed in the cross section of the interface between the glaze layer and the base material is 2 μm or more and 10 μm or less. (5) The ceramic according to any one of (1) to (4), which is sanitary ceramic. (6) The ceramic according to any one of (1) to (5), whose surface has an L* of 84 or more. (7) The ceramic according to any one of (1) to (6), whose surface has a surface roughness Ra of 0.10 μm or less. (8) A method for evaluating the surface aesthetics of pottery, comprising: Prepare pottery with a glaze layer containing an opacifier. The method comprises a step of measuring and calculating the amount of opacifier hidden on the surface of the glaze layer. (9) The method according to (8), wherein the appearance of the pottery is evaluated as being excellent in appearance when the amount of opacifier hiding on the surface of the glaze layer is in the range of 5 μm to 25 μm.

[0074] Regarding the third aspect of the present invention, (1) Pottery comprising at least a base and a glaze layer, The glaze layer contains an opacifier, The pottery has a concealing rate of opacifier and silica sand on the surface of the glaze layer of 4% or more and 24% or less. (2) The pottery according to (1), wherein the opacifier and silica sand hiding ratio of the cross section of the surface layer of the glaze layer is 3.0% or more and 17.5% or less. (3) The pottery according to (1) or (2), wherein the opacifier and silica sand hiding rate of the central cross section of the glaze layer is 3.0% or more and 20% or less. (4) The pottery according to any one of (1) to (3), wherein the opacifier and silica sand hiding ratio at the cross section of the interface between the glaze layer and the base material is 3.0% or more and 11% or less. (5) The ceramic according to any one of (1) to (4), whose surface has an L* of 84 or more. (6) The ceramic according to any one of (1) to (5), whose surface has a surface roughness Ra of 0.10 μm or less. (7) A method for evaluating the surface aesthetics of pottery, comprising: preparing pottery having a glaze layer containing an opacifier and silica sand; The method comprises a step of measuring and calculating the opacifying agent and silica sand hiding rate on the surface of the glaze layer. (8) The method according to (9), wherein the ceramic appearance is evaluated as being excellent in appearance when the opacifier and silica sand hiding ratio on the surface of the glaze layer is in the range of 4% to 24%.

[0075] Regarding the fourth aspect of the present invention, (1) Pottery comprising at least a base and a glaze layer, the glaze layer contains an opacifier and silica sand, The pottery has an opacifying agent and silica sand hiding amount on the surface of the glaze layer of 14 μm or more and 41 μm or less. (2) The pottery according to (1), wherein the opacifier and silica sand hiding amount in the cross section of the surface layer of the glaze layer is 11 μm or more and 20 μm or less. (3) The pottery according to (1) or (2), wherein the opacifier and silica sand hiding amount in the central cross section of the glaze layer is 16 μm or more and 28 μm or less. (4) The pottery according to any one of (1) to (3), wherein the amount of opacifier and silica sand concealed in the cross section of the interface between the glaze layer and the base material is 12 μm or more and 18 μm or less. (5) The pottery according to any one of (1) to (4), wherein the amount of opacifier and silica sand concealed in the surface layer of the cross section is greater than that in the boundary portion of the cross section. (6) The ceramic according to any one of (1) to (5), which is sanitary ceramic. (7) The ceramic according to any one of (1) to (6), whose surface has an L* of 84 or more. (8) The ceramic according to any one of (1) to (7), whose surface has a surface roughness Ra of 0.10 μm or less. (9) A method for evaluating the surface aesthetics of pottery, comprising: preparing pottery having a glaze layer containing an opacifier and silica sand; The method comprises a step of measuring and calculating the amount of opacifier and silica sand hiding on the surface of the glaze layer. (10) The method according to (9), wherein the ceramic appearance is evaluated as being excellent in appearance when the opacifier and silica sand hiding amount on the surface of the glaze layer is 14 μm or more and 41 μm or less.

[0076] Regarding the fifth aspect of the present invention, (1) Pottery comprising at least a base and a glaze layer, The surface of the glaze layer has a du value of 32 or more and 55 or less as measured by a Wavescan DOI measuring device. (2) The pottery according to (2), wherein the maximum height Ry of the surface is 0.25 μm or more and 0.50 μm or less. (3) The ceramic according to (1) or (2), which is sanitary ceramic. (4) The ceramic according to any one of (1) to (3), whose surface has an L* of 84 or more. (5) The ceramic according to any one of (1) to (4), whose surface has a surface roughness Ra of 0.10 μm or less. (6) A method for evaluating the surface aesthetics of pottery, comprising: Prepare pottery with a glaze layer containing an opacifier. The method comprises a step of measuring the du value of the surface of the glaze layer using a Wavescan DOI measuring device. (7) The method according to (6), wherein the appearance of the pottery is evaluated as being excellent in appearance when the du value of the surface of the glaze layer measured with a Wavescan DOI measuring device is 32 or more and 55 or less.

Claims

1. A sanitary ware comprising at least a base and a glaze layer, The glaze layer contains an opacifier, The sanitary ware has a surface of the glaze layer having a maximum height Ry of 0.25 μm or more and 0.50 μm or less, an L* of 84 or more, and a du value measured with a Wavescan DOI measuring device of 32 or more and 55 or less.

2. 2. The sanitary ware according to claim 1, wherein the surface roughness Ra of the surface is 0.10 μm or less.

3. A method for evaluating the surface aesthetics of sanitary ware, comprising: A sanitary ware having a glaze layer containing an opacifier is prepared. The step of measuring the maximum height Ry and L* of the surface of the glaze layer and the step of measuring the du value by a Wavescan DOI measuring device, a method for evaluating the surface of sanitary ware as being excellent in appearance when the maximum height Ry of the surface of the glaze layer is 0.25 μm or more and 0.50 μm or less, L* is 84 or more, and the du value as measured with a Wavescan DOI measuring device is 32 or more and 55 or less.

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