Hygienic ceramic ware provided with matte surface

Abstract

Disclosed is a hygienic ceramic ware provided with a matte surface, said hygienic ceramic ware having a moist and calm texture. A hygienic ceramic ware according to the present invention comprises a ceramic ware base and a glaze layer on the surface thereof, wherein the surface of the glaze layer (1) has a 20° gloss level of 5 or less, a 60° gloss level of 20 or less, and an 85° gloss level of 30 or less, and (2) has a surface roughness Ra of 1.0 μm or greater, and the hygienic ceramic ware imparts to a viewer a moist and calm impression differing from that of conventional matte surfaces. Consequently, it is possible to enhance the appearance (design) of products and harmonize the same with the textures of walls and fixtures in the same space, and design variation is broadened to be able to provide a design space that is unified with the surroundings, for example, and to increase product value.

Description

Sanitary ware with a matte surface

[0001] The present invention relates to a sanitary ware having a matte surface, and more particularly to a sanitary ware having a matte surface with an excellent moist and tranquil texture.

[0002] The appearance of sanitary ware is generally glossy, evoking a sense of luxury and cleanliness. However, matte sanitary ware, the opposite of glossy ware, is highly rated in the market. This is because a matte finish enhances the appearance (design) of the product and allows it to harmonize with the texture of the walls and fixtures in the same space, thereby expanding the variety of designs.

[0003] The matte finish of sanitary ware is basically achieved by scattering light through the formation of irregularities on the surface, which are achieved by the composition of the glaze or by blasting the surface.

[0004] As glazes that achieve a matte finish, for example, JP 2012-046364 A (Patent Document 1) and JP 2023-034495 A (Patent Document 2) disclose glazes that can form a matte surface by precipitating crystal particles during firing. In addition, methods of achieving a matte finish by blasting the surface are disclosed, for example, in JP 2018-104272 A (Patent Document 3) and JP 2020-147492 A (Patent Document 4).

[0005] Although matte-finish sanitary ware is highly rated in the market, there is a demand for an even more improved matte finish. For example, even with a matte finish, the glaze surface tends to produce glare because it has a glass layer, and suppressing this glare has been considered to be one approach to improvement. However, there is currently little knowledge about what index should be used to evaluate the texture of a matte finish to ensure that it is more favorably accepted by users.

[0006] On the other hand, for example, in the case of toilet bowls, a type of sanitary ware, the exterior may have a matte surface, but the bowl-shaped area that receives waste is configured to have a stain-resistant glaze layer. For example, Japanese Patent Application Laid-Open No. 2012-046364 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2023-034495 (Patent Document 2) propose a good matte glaze layer, but state that while such a matte glaze layer may be formed on all surfaces of the sanitary ware, it is preferable that the bowl surface of toilet bowls and urinals have a stain-resistant surface different from that of the present invention, and that a glaze layer with the above-mentioned surface texture be formed on areas other than the bowl surface, specifically the skirt, upper rim, tank body, and tank lid. The provision of these two types of glaze layers results in a boundary between the matte glaze surface and the stain-resistant glaze surface. Proposals have also been made to ensure that this boundary does not detract from the appearance and design of the toilet. For example, Japanese Patent Application Laid-Open No. 2022-062798 (Patent Document 5) states that by applying layers of two properties adjacent to each other so that they do not overlap, it is possible to make it difficult to distinguish between the two.

[0007] JP 2012-046364 A JP 2023-034495 A JP 2018-104272 A JP 2020-147492 A JP 2022-062798 A

[0008] The present inventors have now achieved a matte glaze layer surface with a moist, subdued texture. Specifically, they have discovered that a combination of gloss, color, and surface roughness of the glaze layer surface can give the viewer an impression that is different from that of conventional matte surfaces. The present invention is based on this discovery.

[0009] Therefore, an object of the present invention is to provide a sanitary ware having an improved matte glazed surface.

[0010] Furthermore, when attempting to form two separate glaze layer surfaces with different characteristics and properties on a single piece of sanitary ware, there is a method of separately coating the two surfaces, as described in Patent Document 5. On the other hand, there is a method of forming one glaze layer underneath and the other on a partial area above it, and then coating them in layers. However, when a matte glaze layer is formed on the sanitary ware body and then a stain-resistant or glossy glaze layer is formed on top of that, the boundary between the two surfaces becomes conspicuous, and the appearance of the two surfaces differs significantly, unlike when a non-matte colored glaze layer is applied over the matte glaze layer. To the inventors' knowledge, no prior art has pointed out that this unnatural appearance is a problem, and of course, no solution has been disclosed or suggested.

[0011] The present inventors have now discovered that in sanitary ware, by applying an anti-fouling glaze layer on top of a matte glaze layer in an area where an anti-fouling surface is required, two areas, a matte surface and an anti-fouling surface, can be formed, and by controlling the properties of these two layers to be specific, the boundary between them can be made inconspicuous. For example, the inventors have discovered that the boundary can be made inconspicuous by controlling the gloss, color difference, L value, etc. The present invention is based on this discovery.

[0012] Therefore, an object of the present invention is to provide sanitary ware that has a matte surface and a stain-resistant surface, with the boundary between them being inconspicuous.

[0013] The sanitary ware according to the present invention is a sanitary ware comprising a ceramic base and a glaze layer on the surface thereof, wherein the surface of the glaze layer has the following properties: (1) a 20° gloss level of 5 or less, a 60° gloss level of 20 or less, and an 85° gloss level of 30 or less; and (2) a surface roughness Ra of 1.0 μm or more.

[0014] According to the present invention, there is provided sanitary ware having a matte surface with a soft, subdued texture. By providing such a matte surface that gives a different impression to the viewer than conventional matte surfaces, the appearance (design) of the product can be improved, and it can be made to harmonize with the texture of walls and fixtures in the same space, thereby expanding design variations and, for example, creating a design space that is integrated with the surroundings, thereby increasing the value of the product.

[0015] According to the present invention, there is provided a sanitary ware having a matte surface and a stain-resistant surface, with an inconspicuous boundary between them. The boundary between the first glaze layer and the second glaze layer is inconspicuous and does not give a strong sense of incongruity to the viewer, so that stain-resistant properties can be imparted to areas requiring them without impairing the appearance design, texture, impression, etc. of the sanitary ware as a whole.

[0016] 1 is a SEM image of the glaze surface of Example A1. 2 is a SEM image of the glaze surface of Example A2. 3 is a SEM image of the glaze surface of Example A3. 4 is a SEM image of the glaze surface of Comparative Example A1. 5 is a SEM image of the glaze surface of Comparative Example A2. 6 is a SEM image of the glaze surface of Comparative Example A3. 7 is a SEM image of the glaze surface of Example B1. 8 is a SEM image of the glaze surface of Comparative Example B1. 9 is a SEM image of the glaze surface of Comparative Example B2. 10 is a SEM image of the glaze surface of Comparative Example B3. 11 is a SEM image of the glaze surface of Comparative Example B4. 12 is a cross-sectional schematic diagram of a flush toilet that is a sanitary ware according to a third aspect of the present invention. 13 is an enlarged view of the boundary where two surfaces, where a first glaze layer and a second glaze layer are overcoated, transition from one another in the sanitary ware according to the third aspect of the present invention.

[0017] Definition of Sanitary Ware In the present invention, "sanitary ware" means ceramic products used in toilets and around washrooms, and specifically means toilet bowls, urinals, toilet sinks, toilet tanks, washbasins, hand basins, etc.

[0018] Gloss In this specification, surface gloss of 20°, 60°, and 85° means 20-degree specular gloss, 60-degree specular gloss, and 85-degree surface gloss in a measurement method based on JIS Z8741: Specular Gloss - Measurement Method. That is, in the same measurement method, it means gloss Gs (20°) at an incident angle of 20 degrees, Gs (60°) at an incident angle of 60 degrees, and Gs (85°) at an incident angle of 85 degrees.

[0019] Surface Properties of Glaze Layer on Sanitary Ware The sanitary ware according to the present invention has a basic structure comprising a ceramic body and a glaze layer on the surface thereof. The glaze layer on the sanitary ware according to the present invention satisfies the following surface properties: (1) a 20° gloss of 5 or less, preferably 2 or less, a 60° gloss of 20 or less, preferably 15 or less, and an 85° gloss of 30 or less, preferably 25 or less, and (2) a surface roughness Ra of 1.0 μm or more.

[0020] First Preferred Aspect of the Present Invention The sanitary ware according to the first preferred aspect of the present invention has a basic structure comprising a ceramic body and a glaze layer on the surface thereof. The glaze layer of the sanitary ware according to the present invention satisfies the following surface properties: (1) a 20° gloss of 5 or less, a 60° gloss of 20 or less, and an 85° gloss of 30 or less, (2) an L* value of 50 or more in the Lab color system, and (3) a surface roughness Ra of 1.0 μm or more.

[0021] The surface of the glaze layer that satisfies the above requirements is matte, and moreover, it is a matte surface with a moist, subdued texture, and is a matte surface that suppresses the so-called "glare" seen in conventional matte surfaces. Although it is difficult to quantify the sense of "moist" or "subdued" that an observer has, according to the present invention, such a matte surface can be realized by combining the gloss, color, and surface roughness of the glaze layer surface, and a new matte surface has been provided.

[0022] (1) Glossiness The surface of the glaze layer provided on the sanitary ware according to the present invention has a 20° glossiness of not more than 5, a 60° glossiness of not more than 20, and an 85° glossiness of not more than 30. According to a preferred embodiment of the present invention, the 20° glossiness is not more than 3.5, the 60° glossiness is not more than 18, and the 85° glossiness is not more than 29.

[0023] (2) L* Value The surface of the glaze layer provided on the sanitary ware according to the present invention has an L* value of 50 or more in the Lab color system, and specifically, in addition to so-called white, it also includes beige and light colors known as gray.

[0024] (3) Surface Roughness Ra The surface of the glaze layer of the sanitary ware according to the present invention has a surface roughness Ra of 1.0 μm or more, preferably in the range of 1.1 μm or more and 1.9 μm or less. The surface roughness Ra is an arithmetic mean roughness, and is defined in JIS B 0601:2001 and may be measured in accordance with this standard.

[0025] Second Preferred Aspect of the Present Invention The sanitary ware according to the second preferred aspect of the present invention has a basic structure comprising a ceramic body and a glaze layer on the surface thereof. The glaze layer of the sanitary ware according to the present invention satisfies the following surface properties: (1) a 20° gloss of 2 or less, a 60° gloss of 10 or less, and an 85° gloss of 25 or less, (2) an L* value of less than 50 in the Lab color system, and (3) a surface roughness Ra of 1.0 μm or more.

[0026] The surface of the glaze layer that satisfies the above requirements is a black matte finish, and moreover, it is a matte finish surface with a moist, subdued texture, and is a matte finish surface that suppresses the so-called "glare" seen in conventional matte finish surfaces. While it is difficult to quantify the sense of "moist" or "subdued" that viewers perceive, according to the present invention, such a matte finish surface can be realized by combining the gloss, color, and surface roughness of the glaze layer surface, and a new matte finish surface has been provided.

[0027] (1) Glossiness The surface of the glaze layer provided on the sanitary ware according to the present invention has a 20° glossiness of not more than 2, a 60° glossiness of not more than 15, and an 85° glossiness of not more than 30. According to a preferred embodiment of the present invention, the 20° glossiness is not more than 1.8, the 60° glossiness is not more than 11, and the 85° glossiness is not more than 27.

[0028] (2) L* Value The surface of the glaze layer of the sanitary ware according to the present invention has an L* value of less than 50 in the Lab color system, and specifically, has a dark color that is so-called blackish.

[0029] (3) Surface Roughness Ra The surface of the glaze layer of the sanitary ware according to the present invention has a surface roughness Ra of 1.0 μm or more, preferably in the range of 1.1 μm or more and 1.9 μm or less. The surface roughness Ra is an arithmetic mean roughness, and is defined in JIS B 0601:2001 and may be measured in accordance with this standard.

[0030] Preferred Properties of Glaze Layer The glaze layer provided on the sanitary ware according to the present invention comprises a crystalline phase and an amorphous phase (non-crystalline phase), and according to a preferred embodiment of the present invention, the amorphous phase accounts for 70 wt % or more of the glaze layer, and the amorphous phase accounts for 90 wt % or less of the glaze layer.

[0031] According to one aspect of the present invention, the crystalline phase is preferably diopside (CaMgSi ２ O ６ ) or Augite ((Ca, Mg, Fe)2Si ２ O ６ ). By including these, it is possible to more effectively realize a moist and calm texture on the matte surface. According to a preferred embodiment of the present invention, the crystalline phase preferably contains diopside or augite in an amount of 70% or more of the crystalline phase. Furthermore, in a second embodiment of the present invention, the crystalline phase contains cristobalite. This makes it possible to more effectively realize a moist and calm texture on the matte surface.

[0032] According to one embodiment of the present invention, the crystalline phase contains 0.5 wt % to 5 wt % of zircon, and preferably the particle size of this zircon is about 0.3 to 0.8 μm.

[0033] In the present invention, the amounts of the crystalline phase and amorphous phase, the amounts of diopside and augite, and the amount and particle size of zircon can be calculated, for example, from an SEM image of the surface of the glaze layer using image processing software.

[0034] Glaze The glaze used to form the glaze layer according to the present invention is not particularly limited as long as it can achieve the surface properties described above, but typically the glaze raw material is a mixture of natural mineral particles such as silica sand, feldspar, and limestone. The pigment is, for example, a cobalt compound or an iron compound, and the opacifier is, for example, zirconium silicate or tin oxide. An amorphous glaze is a glaze obtained by melting a glaze raw material consisting of a mixture of the above-mentioned natural mineral particles at a high temperature and then rapidly cooling it to vitrify it; for example, a frit glaze is preferably used.

[0035] According to a preferred embodiment of the present invention, the preferred glaze composition is, for example, 15 wt% to 30 wt% feldspar, 25 wt% to 45 wt% silica sand, 0 to 10 wt% dolomite, 10 wt% to 20 wt% calcium carbonate, 4 wt% to 20 wt% alumina, 10 wt% or less zinc oxide, 10 wt% or less zircon in the first embodiment, 10 wt% or less black pigment in the second embodiment, 11 wt% to 15 wt% talc, and 15 wt% or less stain.

[0036] Examples of black pigments include V ２ O ５ , Cr ２ O ３ , MnO, Fe ２ O ３ , Co ２ O ３ , NiO, etc.

[0037] The preferred composition of the glaze layer of the sanitary ware according to the present invention is SiO ２ 60 to 67 wt% of Al ２ O ３6 to 15 wt%, CaO is 11 wt% or less (more preferably 6 to 11 wt%), MgO is 3 to 9 wt%, K ２ O is 2 wt% or less (more preferably 0.5 to 2 wt%), Na ２ O is 0.5 to 3 wt % and ZnO is 3 wt % or more (more preferably 3 to 10 wt %).

[0038] In the first aspect of the present invention, the element ratio of Mg to Ca is preferably 0.45 to 0.50, more preferably 0.45 to 0.48. More preferably, MgO is 4 wt %. By using such amounts of Mg and Ca, diopside crystals can be easily formed.

[0039] In the second aspect of the present invention, the element ratio of Mg to Ca is preferably 0.3 to 0.4, more preferably 0.31 to 0.35. More preferably, MgO is 4 wt %. By using such amounts of Mg and Ca, diopside crystals can be easily formed.

[0040] The ceramic body of the sanitary ware according to the present invention is not particularly limited and may be a normal sanitary ware body. An intermediate glaze layer may be provided under the outermost glaze layer having the above-described surface texture.

[0041] Manufacturing Method The sanitary ware according to the present invention can be preferably manufactured by the following method. First, a sanitary ware body is formed into an appropriate shape by slip casting using a water-absorbent mold with a sanitary ware body slurry prepared from raw materials such as silica sand, feldspar, and clay. The surface of the dried molded body is then coated with a glaze raw material slurry by an appropriate common method such as spray coating, dip coating, spin coating, or roll coating. The resulting molded body with a precursor layer for the surface glaze layer formed thereon is allowed to stand until the surface glaze layer is sufficiently dried, and the dried surface is scraped to make it uniform and smooth, after which it is fired. The firing temperature is preferably between 1,000°C and 1,300°C, at which the sanitary ware body sinters and the glaze softens.

[0042] Basic configuration of the third preferred embodiment of the present invention Fig. 12 shows a schematic cross-sectional view of a flush toilet, an example of sanitary ware according to the third embodiment of the present invention. The flush toilet in the figure has a glaze layer on a ceramic base, with the exterior of the toilet having a first glaze surface as the surface of the first glaze layer, and the waste receiving surface 2 of the bowl, which may come into contact with waste, having a second glaze surface as the surface of the second glaze layer. In the figure, the surface indicated by dashed line 11 is the first glaze surface, and the surface indicated by dotted line 12 on waste receiving surface 2 is the second glaze surface.

[0043] More specifically, the toilet bowl of Figure 12 according to the present invention has a first glaze layer formed over the entire outer surface of the toilet bowl, and a second glaze layer formed by overcoating on a portion of that area, the waste receiving surface 2. As a result, as shown in Figure 12, a first glaze surface 11 is formed in the area that will become the exterior of the toilet bowl, and in addition, the first glaze layer is first formed on the waste receiving surface 2, and then a second glaze layer is formed on top of that, forming a second glaze surface, resulting in a multi-coating configuration.

[0044] The first glaze layer having the properties specified herein provides a so-called matte surface as the first glaze surface, and the second glaze layer having the properties specified herein provides a so-called anti-fouling surface as the second glaze surface. Thus, in the toilet bowl of Figure 12, a matte surface 11 is formed in the area that will become the exterior of the toilet bowl, and the first glaze layer is first formed on the waste-receiving surface 2, and then a second glaze layer is formed on top of that, resulting in an anti-fouling surface as the second glaze surface. In other words, the dotted line 12 indicating the second glaze surface in Figure 12 is the surface of a layer formed by superimposing the second glaze layer on top of the first glaze layer, and represents the anti-fouling surface.

[0045] In the present invention, the first glaze layer and the second glaze layer meet at a boundary, for example, inside the bowl. Figure 13 is an enlarged view of this boundary. As shown in Figure 13, in the present invention, a first glaze layer 11 is formed on a ceramic body 10, and a second glaze layer 12 is formed on top of that, with the boundary 14 being the boundary between the two.

[0046] The surfaces of the first glaze layer and the second glaze layer of the sanitary ware according to the third aspect of the present invention each have the following properties: the surface roughness (Ra) of the first glaze surface is 1 μm or more, the surface roughness (Ra) of the second glaze surface is less than 1 μm, preferably 0.1 μm or less, and more preferably 0.07 μm or less, the 60° gloss of the second glaze surface is higher than that of the first glaze surface, the color difference ΔE between the first and second glaze surfaces is 17 or less, preferably ΔE is 10 or less, and the L value of the second glaze surface is lower than that of the first glaze surface.

[0047] In the sanitary ware according to the present invention, which satisfies the above requirements, the boundary between the first and second glaze layers is not conspicuous and does not give a strong sense of incongruity to the viewer. Such a boundary that is not inconspicuous has the advantage that stain resistance can be imparted to areas that require it without impairing the appearance design, texture, impression, etc. of the sanitary ware as a whole.

[0048] The surface of the matte glaze layer is uneven, thereby achieving a matte texture with no gloss. On the other hand, the glaze layer that provides anti-fouling properties or gloss is smoothed to achieve a glossy surface that is resistant to stain adhesion and easy to remove. When an anti-fouling glaze layer is applied to a matte glaze layer, the surface of the anti-fouling glaze layer is affected by the unevenness of the underlying matte surface. Therefore, it is preferable to apply a relatively thick anti-fouling glaze layer. Simply increasing the thickness of the anti-fouling glaze layer would make the boundary between the two surfaces more noticeable, resulting in a significant difference in appearance between the two surfaces and a sense of incongruity, which is also dependent on the viewer's perception. However, in the present invention, by satisfying the above requirements, the color difference between the two surfaces is particularly reduced, and by specifying the relative relationship between the surface brightness of the underlying matte glaze layer (the second glaze layer) and the surface brightness of the upper anti-fouling glaze layer (the first glaze layer), the sense of incongruity felt by the viewer can be reduced.

[0049] According to one preferred embodiment of the third aspect of the present invention, the first glaze surface has a 20-degree gloss of 5 or less, a 60-degree gloss of 20 or less, and an 85-degree gloss of 30 or less, and the second glaze surface has a 20-degree gloss of 60 or less, a 60-degree gloss of 90 or less, and an 85-degree gloss of 98 or less. In this embodiment, the sense of incongruity at the boundary is further suppressed.

[0050] According to one aspect of the third aspect of the present invention, the difference in thickness between the first glaze layer and the second glaze layer is 0.2 mm or less. According to a more preferred aspect, the thickness of the first glaze layer is greater than the thickness of the second glaze layer. According to another preferred aspect, the thickness of the first glaze layer is 0.4 to 1.0 mm, and the thickness of the second glaze layer is 0.2 to 0.8 mm. By satisfying these requirements, the sense of incongruity at the boundary between the first glaze layer and the second glaze layer is further suppressed.

[0051] According to another aspect of the present invention, the boundary between the first and second glaze layers is located on a vertical surface of the sanitary ware. For example, a boundary 13 is provided on the vertical surface inside the rim portion 3 in Fig. 12. This further reduces the sense of incongruity at the boundary between the first and second glaze layers.

[0052] Glaze of First Glaze Layer In the present invention, examples of the matte glaze layer that is the first glaze layer include those described in JP-A-6-211541, JP-A-2-229736, and JP-A-2012-046364.

[0053] Furthermore, a preferred matte glaze layer in the present invention is as follows: The sanitary ware according to the present invention has a basic structure comprising a ceramic body and a glaze layer on its surface. The glaze layer of the sanitary ware according to the present invention satisfies the following surface properties: a 20° gloss level of 5 or less, a 60° gloss level of 20 or less, an 85° gloss level of 30 or less, and a surface roughness Ra of 1.0 μm or more. According to a preferred embodiment of the present invention, the 20° gloss level is 3.5 or less, the 60° gloss level is 18 or less, and the 85° gloss level is 29 or less.

[0054] The surface of the glaze layer that satisfies the above requirements is matte, and moreover, it is a matte surface with a moist, subdued texture, and is a matte surface that suppresses the so-called "glare" seen in conventional matte surfaces. Although it is difficult to quantify the sense of "moist" or "subdued" that an observer has, according to the present invention, such a matte surface can be realized by combining the gloss, color, and surface roughness of the glaze layer surface, and a new matte surface has been provided.

[0055] The surface of the matte glaze layer of the sanitary ware according to the present invention has a surface roughness Ra of 1.0 μm or more, preferably in the range of 1.1 μm or more and 1.9 μm or less. The surface roughness Ra is an arithmetic mean roughness, and is defined in JIS B 0601:2001 and may be measured in accordance with this standard.

[0056] The matte glaze layer provided on the sanitary ware according to the present invention is composed of a crystalline phase and an amorphous phase (non-crystalline phase), and according to a preferred embodiment of the present invention, the amorphous phase accounts for 70 wt % or more and 90 wt % or less of the glaze layer.

[0057] According to one aspect of the present invention, the crystalline phase is preferably diopside (CaMgSi ２ O ６ ) or Augite ((Ca, Mg, Fe)2Si ２ O ６ ) is contained. By including these, it is possible to realize a moist and calm texture on the matte surface better. According to a preferred embodiment of the present invention, the crystalline phase of diopside or augite preferably accounts for 70% or more of the crystalline phase. Alternatively, according to one embodiment of the present invention, the crystalline phase is preferably diopside (Diopside, CaMgSi ２ O ６ ) or Augite ((Ca, Mg, Fe)2Si ２ O ６). By including these, it is possible to more effectively realize a moist and calm texture on the matte surface. According to a preferred embodiment of the present invention, the crystalline phase preferably contains diopside or augite in an amount of 70% or more of the crystalline phase. Furthermore, according to another preferred embodiment of the present invention, the crystalline phase contains cristobalite. This makes it possible to more effectively realize a moist and calm texture on the matte surface.

[0058] According to one embodiment of the present invention, the crystalline phase contains 0.5 wt % to 5 wt % of zircon, and preferably the particle size of this zircon is about 0.3 to 0.8 μm.

[0059] In the present invention, the amounts of the crystalline phase and amorphous phase, the amounts of diopside and augite, and the amount and particle size of zircon can be calculated, for example, from an SEM image of the surface of the glaze layer using image processing software.

[0060] The glaze used to form the glaze layer according to the present invention is not particularly limited as long as it can achieve the surface properties described above, but typically the glaze raw material is a mixture of natural mineral particles such as silica sand, feldspar, and limestone. The pigment is, for example, a cobalt compound or an iron compound, and the opacifier is, for example, zirconium silicate or tin oxide. The amorphous glaze is a glaze obtained by melting a glaze raw material consisting of a mixture of the above-mentioned natural mineral particles at a high temperature and then rapidly cooling it to vitrify it; for example, a frit glaze is preferably used.

[0061] According to a preferred embodiment of the present invention, the matte glaze composition is, for example, 15 wt% to 30 wt% feldspar, 25 wt% to 45 wt% silica sand, 0 to 10 wt% dolomite, 10 wt% to 20 wt% calcium carbonate, 4 wt% to 20 wt% alumina, 10 wt% or less zinc oxide, 10 wt% or less zircon, 11 wt% to 15 wt% talc, and 15 wt% or less stain.

[0062] The preferred composition of the matte glaze layer provided on the sanitary ware according to the present invention is SiO ２ 60 to 67 wt% of Al ２ O ３6 to 15 wt%, CaO is 11 wt% or less (more preferably 6 to 11 wt%), MgO is 3 to 9 wt%, K ２ O is 2 wt% or less (more preferably 0.5 to 2 wt%), Na ２ O is 0.5 to 3 wt % and ZnO is 3 wt % or more (more preferably 3 to 10 wt %).

[0063] According to a preferred embodiment of the present invention, the element ratio of Mg to Ca is 0.45 to 0.50, more preferably 0.45 to 0.48. More preferably, the MgO content is 4 wt %. By adjusting the Mg and Ca content in this range, diopside crystals are easily formed.

[0064] Glaze of Second Glaze Layer In the present invention, examples of the antifouling glaze layer that is the second glaze layer include those described in WO99 / 061392 and JP-A 2002-206269.

[0065] The second glaze layer is preferably formed using a glaze raw material consisting of a mixture of natural mineral particles, such as silica sand, feldspar, and limestone, and an amorphous raw material. The amorphous raw material is a glaze raw material obtained by melting and vitrifying a mixture of natural mineral particles, such as silica sand, feldspar, and limestone, at high temperature. For example, a frit raw material is suitable. Furthermore, the silica sand containing quartz particles used here is preferably micronized. This reduces the likelihood of quartz particles remaining on the glaze surface after firing. To prepare a stain-resistant glaze, the natural mineral particle mixture and the amorphous raw material are mixed so that the ratio of amorphous glaze to the total of the two is preferably 50 to 99% by weight, more preferably 60 to 90% by weight. The mixture is then mixed in a ball mill or the like and, if necessary, pulverized.

[0066] The glaze composition of the second glaze layer is preferably as follows: SiO ２ 52 to 76 wt% Al ２ O ３ 6-14 wt% MgO 0.5-4 wt% CaO 6-17 wt% ZnO 3-11 wt% K ２ O is 1 to 5 wt% Na ２ O is 0.5 to 2.5 wt%

[0067] Furthermore, according to a preferred embodiment of the present invention, the surface of the second glaze layer is made highly smooth, with Ra defined in JIS B 0601:2001 being 0.1 μm or less, more preferably 0.07 μm or less.

[0068] The present invention will be further illustrated by the following examples, but the present invention is not limited to these examples.

[0069] Examples A1 to A3: 2 kg of natural mineral particles having the composition and particle size shown in Table 1 below, 1 kg of water, and 4 kg of spheres were placed in a 6-liter ceramic pot and ground in a ball mill for approximately 24 hours to obtain a glaze slurry. Next, a 70 x 70 mm plate-shaped test specimen was prepared using a sanitary ware base slurry prepared from raw materials such as silica sand, feldspar, and clay. The glaze was spray-coated onto this plate-shaped test specimen to a thickness of 1.0 mm or more using a wet spray method, and the specimen was left to dry sufficiently. The dried surface was then scraped to make it uniform and smooth, and then fired at 1100 to 1200°C. In this manner, samples for Examples A1 to A3 were obtained.

[0070] In addition, in the same manner as in Examples A1 to A3, samples of Examples A4 to A8 and Comparative Example A4 having the compositions shown in Table 3 below were prepared by adjusting the ranges of feldspar to 15 wt % to 30 wt %, silica sand to 25 wt % to 45 wt %, dolomite to 0 wt %, calcium carbonate to 10 wt % to 20 wt %, alumina to 4 wt % to 20 wt %, zinc oxide to 10 wt % or less, zircon to 10 wt % or less, talc to 11 wt % to 15 wt %, and stain to 15 wt % or less.

[0071] Comparative Examples A1 to A3 The following three commercially available products with a matte glaze layer were obtained and designated as Comparative Examples 1 to 3. Comparative Example A1: Washbasin manufactured by Company A Comparative Example A2: Washbasin manufactured by Company B Comparative Example A3: Washbasin manufactured by Company C

[0072] Composition of Glaze Layer The compositions of the glaze layers of Examples A1 to A8 and Comparative Examples A1 to A4 were analyzed. The specific analysis method was to measure using a fluorescent X-ray analyzer (ZXS Primus IV, manufactured by Rigaku Corporation) at a voltage of 30 to 50 kV, a current of 60 to 100 mA, and a measurement area of ​​20 mmφ. The results are shown in the table below.

[0073] Measurement of Gloss The gloss of the surface of the glaze layer of Examples A1 to A8 and Comparative Examples A1 to A4 was measured according to JIS Z8741 using a glossmeter (Konica Minolta: Multi-Gloss 268) with a measurement area of ​​10 mm x 10 mm at a measurement angle of 20°, an ellipse with a measurement area of ​​9 mm x 15 mm at a measurement angle of 60°, and an ellipse with a measurement area of ​​5 mm x 38 mm at a measurement angle of 85°. The results are shown in Table 4 below.

[0074] Measurement of Surface L* Value The L* values ​​of the surfaces of the glaze layers of Examples A1 to A8 and Comparative Examples A1 to A4 were measured using a spectrophotometer (KONICA MINOLTA: CM-3700A) with a measuring diameter of 25.4 mm, specular reflection light treatment: SCE, and light source: D65. The results are shown in Table 4 below.

[0075] Measurement of surface roughness Ra The Ra values ​​of the surfaces of the glaze layers of Examples A1 to A8 and Comparative Examples A1 to A4 were measured using a laser microscope (OPTELICS HYBRID+ manufactured by Lasertec) with cutoff values ​​of λc: 0.8 mm and λs: 0.0025 mm. The results are shown in Table 4 below.

[0076]

[0077] SEM Image Analysis: Crystalline Phase and Amorphous Phase SEM images of the surfaces of the glaze layers of Examples A1 to A3 and Comparative Examples A1 to A3 were taken. The images are shown in Figures 1 to 6. From these SEM images, image analysis software was used to calculate (1) the proportions of the crystalline phase and the amorphous phase, and (2) the presence and amount of diopside or augite in the crystalline phase. For the calculation, SEM images of 60 μm × 80 μm per field were taken from three fields per sample, and the particles were binarized and calculated from the area ratio.

[0078] The results are shown in the table below.

[0079] Measurement of particle size Three SEM images of the surface of the glaze layer of Examples A1 to A3, each with a field of view of 60 μm × 80 μm, were taken for each sample, and the major diameters of crystal particles other than zircon were counted in 5 μm increments. The results are shown in the table below.

[0080] Evaluation of Matte Finish Ten engineers involved in the development of sanitary ware were selected as panelists and visually observed the surfaces of the glaze layers of Examples A1 to A8 and Comparative Examples A1 to A4. They evaluated the expressions suitable for expressing the matte finish of the surfaces in accordance with the following criteria 1 and 2, and calculated the average of the assigned scores, excluding the maximum and minimum values.

[0081] <Criteria 1> 5 points: A fine-grained matte surface. 4 points: A matte surface that is slightly shiny but not noticeable. 3 points: A fine-grained matte surface, but the glare is noticeable. 2 points: A matte surface that is shiny. 1 point: A matte surface that is shiny and rough (the surface is rough or appears to be rough).

[0082] <Criterion 2> 5 points: Calm 4 points: Somewhat calm 3 points: Neither 2 points: Somewhat restless 1 point: Restless

[0083] The results are shown in the table below.

[0084] Examples B1 to B3: 2 kg of natural mineral particles having the composition shown in Table 1 and the particle size shown in Table 2 below, 1 kg of water, and 4 kg of spheres were placed in a 6-liter ceramic pot and ground in a ball mill for approximately 24 hours to obtain a glaze slurry. Next, a 70 x 70 mm plate-shaped test specimen was prepared using a sanitary ware base slurry prepared from raw materials such as silica sand, feldspar, and clay. The glaze was spray-coated onto this plate-shaped test specimen to a thickness of 1.0 mm or more using a wet spray method, and the specimen was left to dry sufficiently. The dried surface was polished to smooth it, and then fired at 1100 to 1200°C to obtain samples of Examples B1 to B3.

[0085] In addition, a sample of Comparative Example B6 having the composition shown in Table 3 below was prepared in the same manner as Example B1, except that the feldspar was adjusted to 15 wt% to 30 wt%, silica sand to 25 wt% to 45 wt%, dolomite to 0 wt%, calcium carbonate to 10 wt% to 20 wt%, alumina to 4 wt% to 20 wt%, zinc oxide to 10 wt% or less, zircon to 10 wt% or less, talc to 11 wt% to 15 wt%, and stain to 15 wt% or less.

[0086] Comparative Examples B1 to B5 The following five commercially available products with a black matte glaze layer were obtained and designated as Comparative Examples 1 to 5. Comparative Example B1: Washbasin manufactured by Company A Comparative Example B2: Washbasin manufactured by Company B Comparative Example B3: Washbasin manufactured by Company C Comparative Example B4: Washbasin manufactured by Company D Comparative Example B5: Flush toilet manufactured by Company E

[0087] Composition of Glaze Layer The compositions of the glaze layers of Examples B1 and B2 and Comparative Examples B1 to B6 were analyzed using the same analytical method as in Example A. The results are shown in the table below.

[0088] Measurement of Glossiness The glossiness of the surface of the glaze layer of Examples B1 and B2 and Comparative Examples B1 to B6 was measured in the same manner as in Example A. The results are shown in Table 4 below.

[0089] Measurement of Surface L* Value The L* values ​​of the surfaces of the glaze layers of Examples B1 and B2 and Comparative Examples B1 to B6 were measured in the same manner as in Example A. The results are shown in Table 4 below.

[0090] Measurement of Surface Roughness Ra The surface roughness Ra values ​​of the surfaces of the glaze layers of Examples B1 and B2 and Comparative Examples B1 to B6 were measured in the same manner as in Example A. The results are shown in Table 4 below.

[0091]

[0092] SEM Image Analysis: Crystalline Phase and Amorphous Phase SEM images of the surfaces of the glaze layers of Example B1 and Comparative Examples B1 to B4 were taken. The images are shown in Figures 7 to 11. From these SEM images, image analysis software was used to calculate (1) the proportions of the crystalline phase and the amorphous phase, and (2) the presence and amount of diopside or augite in the crystalline phase. For the calculation, SEM images of 60 μm × 80 μm per field were taken in three fields per sample, and the particles were binarized and calculated from the area ratio.

[0093] The results are shown in the table below.

[0094] Measurement of particle size Three SEM images of the surface of the glaze layer of Example B1, each with a field of view of 60 μm × 80 μm, were taken for each sample, and the major axis of crystal particles other than zircon was counted in 5 μm increments. The results are shown in the following table.

[0095] Evaluation of Matte Tone Ten engineers involved in the development of sanitary ware were selected as panelists to visually observe the surfaces of the glaze layers of Examples B1 to B8 and Comparative Examples B1 to B4, and evaluated the expressions suitable for expressing the matte tone of the surfaces using the same criteria as in Example A.

[0096] The results are shown in the table below.

[0097] Example C: Glaze Formulation and Glazing Method (1) Preparation of Ceramic Body Test Pieces Next, 70 x 70 mm plate-shaped test pieces were prepared using sanitary ware body slurry prepared from raw materials such as silica sand, feldspar, clay, etc. (2) Glaze for First Glaze Layer (Matte Glaze) 2 kg of natural mineral particles having the composition shown in Table 1 and the particle size shown in Table 2 below, 1 kg of water, and 4 kg of spherical stones were placed in a 6-liter ceramic pot and pulverized in a ball mill for approximately 24 hours to obtain a glaze slurry.

[0098] (3) Glaze for the second glaze layer (anti-fouling glaze): 2 kg of the glaze raw material (adjusted so that the ratio of amorphous glaze to the total of the raw materials and the amorphous glaze was 50-99 wt.%), 1 kg of water, and 4 kg of spheres were placed in a 6-liter ceramic pot, and the mixture was pulverized in a pot mill so that the particle size of the glaze slurry after pulverization was 67% below 10 μm and the 50% average particle size (D50) was 6.0 μm. The amorphous raw material was a glaze raw material consisting of a mixture of natural mineral particles such as silica sand, feldspar, and limestone, which was melted at high temperature and vitrified.

[0099] Raw material composition SiO ２ 52 to 76 wt% Al ２ O ３ 6-14 wt% MgO 0.5-4 wt% CaO 6-17 wt% ZnO 3-11 wt% K ２ O is 1 to 5 wt% Na ２ O is 0.5 to 2.5 wt%

[0100] Examples C1 to C4: The glaze for the first glaze layer obtained in (2) above was spray-coated onto the plate-shaped test piece obtained in (1) above to a thickness of 1.0 mm or more by wet spray coating, and the test piece was left to dry sufficiently. The dried surface was then scraped to make it uniform and smooth. Then, the antifouling glaze obtained from the glaze for the second glaze layer in (3) above was spray-coated onto only half of the test piece to a thickness of 0.3 to 0.4 mm by wet spray coating. The test piece was then fired at 1100 to 1200°C to obtain samples of Examples C1 to C4.

[0101] The Lab values, color difference, surface roughness, and gloss of the obtained samples of Examples C1 to C4 were measured, and the results are shown in the table below.

[0102] A sample was obtained in the same manner as in Example C1, except that, before applying the glaze for the second glaze layer (anti-fouling glaze), a glossy glaze having the following composition was applied by wet spray coating to a thickness of 0.15 mm or more, and then the glaze for the second glaze layer (anti-fouling glaze) was applied. This was designated Comparative Example 1.

[0103] Glossy glaze raw material composition

[0104] The Lab value, color difference, surface roughness, and gloss of the obtained sample of Comparative Example C1 were measured, and the results are shown in the table below.

[0105] Evaluation The appearance of Example C1 and Comparative Example C1 was evaluated under the following conditions. Specifically, the samples were placed under 100-150 lux, which is the illuminance of a typical toilet space, using two types of standard illuminant light sources for colorimetry, D65 light source and A light source. Fifteen sanitary ware engineers were shown the samples visually and asked the following questions and their reasons for their opinions: Question 1: Which combination do you prefer? Question 2: Which combination feels most natural?

[0106] The number of respondents and their reasons are shown in the following table.

[0107] Question 1 (preference for combination) showed differences in preference, but question 2 (whether it felt strange) clearly rated the example higher.

Claims

1. Sanitary ware comprising a ceramic base and a glaze layer on the surface thereof, wherein the surface of the glaze layer has the following properties: (1) a 20° gloss of 5 or less, a 60° gloss of 20 or less, and an 85° gloss of 30 or less; and (2) a surface roughness Ra of 1.0 μm or more.

2. The sanitary ware according to claim 1, wherein the glaze layer contains 70 wt % to 90 wt % of an amorphous (non-crystalline phase).

3. The sanitary ware according to claim 1 or 2, wherein the glaze layer contains a crystalline phase, and the crystalline phase contains diopside or augite.

4. The sanitary ware according to claim 3, wherein the crystalline phase of diopside or augite accounts for 70% or more of the crystalline phase.

5. The sanitary ware according to claim 3, wherein the crystalline phase contains 0.5 wt% to 5 wt% zircon (opacifier).

6. The sanitary ware according to claim 3, wherein the crystalline phase includes cristobalite.

7. The sanitary ware according to claim 1, wherein the glaze layer contains 3 wt % or more of ZnO.

8. The glaze layer contains 11 wt% or less of CaO and K ２ 8. The sanitary ware according to claim 7, containing 2 wt % or less of O.

9. The sanitary ware according to any one of claims 1 to 8, characterized in that the glaze layer comprises a first glaze surface and a second glaze surface, the first glaze surface and the second glaze surface are formed in the glaze layer by forming a second glaze layer on a partial region of the first glaze layer that provides the first glaze surface, the surface roughness (Ra) of the first glaze surface is 1 μm or more, the surface roughness (Ra) of the second glaze surface is less than 1 μm, the 60° gloss of the second glaze surface is higher than that of the first glaze surface, the color difference ΔE between the first glaze surface and the second glaze surface is 17 or less, and the L value of the second glaze surface is lower than that of the first glaze surface.

10. The sanitary ware according to claim 9, wherein the first glaze surface is a matte glaze layer surface, and the second glaze surface is a stain-resistant glaze layer surface.

11. The sanitary ware according to claim 9, wherein the thickness of the first glaze layer is greater than the thickness of the second glaze layer.

Images