JP7823322B2 - Antiviral agent containing yttrium or an yttrium compound, glaze containing said antiviral agent, and antiviral sanitary ware glazed with said glaze - Google Patents

Description

The present invention relates to an antiviral agent containing yttrium or an yttrium compound, a glaze containing the antiviral agent, and antiviral sanitary ware coated with the glaze.

There have been reports of composite oxides being given antiviral properties. WO 2020/017493 A1 (Patent Document 1) suggests that composite oxide ceramics containing rare earth elements and other specific metal elements have both water repellency and antibacterial/antiviral properties. Specifically, it discloses that calcined powder (500°C) of composite oxide ceramics (LMO) containing lanthanum (La) and molybdenum (Mo) exhibits higher activity against bacteriophages Qβ and Φ6 than single oxides (La ₂ O ₃ particles) (paragraphs 0067, 0069-0071, and Figure 8).

Patent Document 1 does not compare the results with single oxides, but it does disclose that calcined powders (500°C, 400°C, or 550°C) of composite oxide ceramics containing lanthanum (La) and molybdenum (Mo) and/or tungsten (W) (LMO, LWO, LCMO (LMO in which part of the La is replaced with cerium (Ce)), LMWO (LMO in which part of the Mo is replaced with W)) exhibit activity against bacteriophages Qβ and Φ6 (Figures 11, 14-17, 20).

Furthermore, Cosmetology Research Report Vol. 28, 2020, pp. 43-52 (Non-Patent Document 1), written by the inventor of Patent Document 1, also discloses the same content as Patent Document ₂ , that is, _CeO2 shows almost no activity against bacteriophages Qβ and Φ6, whereas _La2O3 shows some activity, and that the anti-Qβ and Φ6 activity of _La2O3 is lower than that of LMO (page 47 _, right column, second paragraph, Figure 7).

Furthermore, examples of imparting antiviral properties to liquid compositions have been reported. JP 2020-111546 A (Patent Document 2) proposes an antiviral composition containing a rare earth salt, a zinc salt, and water. Specifically, it discloses that an aqueous solution containing lanthanum chloride, cerium chloride, neodymium chloride, or ytterbium acetate, and zinc gluconate has a lower viral infectivity (Log(PFU)), i.e., higher antiviral properties, than an aqueous solution lacking either the rare earth salt or the zinc salt. Patent Document 2 discloses processing the antiviral composition into fibers and also suggests processing it into a coating agent such as a paint, but does not disclose processing it into ceramic materials or sanitary ware.

On the other hand, a glaze layer is formed on the outermost surface of sanitary ware to ensure a hygienic surface and to ensure an attractive appearance. To improve hygiene, a technology has been proposed in which an antibacterial agent is added to the glaze layer. For example, CN111393188A (Patent Document 3) discloses sanitary ware comprising a base glaze layer and a top glaze layer containing a nanosilver antibacterial agent. However, Patent Document 3 does not take into consideration sanitary ware with antiviral properties.

Japanese Patent Laid-Open Publication No. 2000-159619 (Patent Document 4) reports that forming a film of yttrium (Y) oxide or a film of Y oxide and cerium (Ce) oxide on the surface of a tile reduces the buildup of water scale and provides antifouling properties. According to Patent Document 4, Y has a high contact angle with water, provides good water repellency, and has hardness suitable for the durability required of sanitary ware such as tiles. Patent Document 4 also discloses that providing a glaze layer between the tile and the Y oxide film or Y/Ce oxide film (i.e., separate from the Y oxide film or Y/Ce oxide film) and adding an antibacterial agent (silver, copper, or zinc atoms, a quaternary amine, titanium oxide, zinc oxide, etc.) to this glaze layer improves antifouling properties.
As can be understood from the disclosure of such reference 4, the reference merely discloses sanitary ware having stain-resistant properties that utilize the hardness and water repellency of yttrium, and therefore the reference does not disclose or suggest at all the technical idea that yttrium has antibacterial or even antiviral properties.

To date, there have been no known reports that yttrium, a rare earth element, has antiviral properties. Furthermore, adding additives to glazes generally roughens the surface of sanitary ware, which can be undesirable from the standpoint of stain resistance or design.

WO2020/017493A1 publication Japanese Patent Application Laid-Open No. 2020-111546 CN111393188A publication Japanese Patent Application Laid-Open No. 2000-159619

Cosmetology Research Report Vol. 28, 2020, pp. 43-52

The inventors have now experimentally confirmed that yttrium has antiviral properties. Specifically, they have experimentally confirmed that a glaze layer containing yttrium obtained by firing a glaze containing an yttrium compound as a starting material exhibits antiviral properties, and furthermore, that the yttrium in the glaze layer alone exhibits practical antiviral properties. The present invention is based on these findings.

Accordingly, the present invention aims to provide an antiviral agent containing yttrium or an yttrium compound. It also aims to provide an antiviral glaze that utilizes the antiviral properties of yttrium or an yttrium compound, and sanitary ware equipped with an antiviral glaze layer obtained by firing the glaze.

The antiviral agent according to the present invention is characterized by containing yttrium or an yttrium compound as an active ingredient.
The glaze according to the present invention is characterized in that it contains yttrium or an yttrium compound as an antiviral agent.
The sanitary ware according to the present invention is
A pottery body and a glaze layer formed on the surface of the pottery body,
The glaze layer is characterized by containing yttrium (Y) as an antiviral agent.

The present invention provides an antiviral agent containing yttrium or an yttrium compound. The present invention also provides an antiviral glaze that utilizes the antiviral properties of yttrium or an yttrium compound, and sanitary ware equipped with an antiviral glaze layer obtained by firing the glaze.

1 is a schematic diagram of a sanitary ware according to the present invention. FIG. 1 is a schematic diagram of a sanitary ware according to one embodiment of the present invention. 1 shows an XRD pattern of a glaze layer containing yttrium. 1 is an SEM image of the surface of the glaze layer of the sanitary ware according to the present invention, showing the state in which yttrium (Y) is present in a spinodal phase separation state on the surface of the glaze layer. 1 is a cross-sectional TEM image of a glaze layer of a sanitary ware according to the present invention, showing that yttrium (Y) is present in a spinodal phase separation state near the surface of the glaze layer.

In this invention , "sanitary ware" refers to ceramic products used in toilets and around washrooms, specifically toilet bowls, urinals, toilet strainers, toilet tanks, washbasins, hand basins, etc. Furthermore, "pottery" refers to ceramics with a slightly absorbent base that has been fired and has a glazed surface.

In addition, with regard to the present invention, the statement that the yttrium in the glaze layer "single-handedly" exhibits practical antiviral properties means that, while the composite oxide disclosed in Patent Document 1 exhibits antiviral properties by being composed of lanthanum and other metal elements (Mo, W), and the liquid composition disclosed in Patent Document 2 exhibits antiviral properties by containing a rare earth salt and other metal salt (zinc salt), yttrium itself exhibits practical antiviral properties.

As described above, the present invention was made possible by the discovery that yttrium has antiviral properties, i.e., by the discovery of new performance, action, or use of yttrium. One aspect of the present invention provides sanitary ware containing the antiviral agent of the present invention. Below, the antiviral agent of the present invention will be described in detail together with the sanitary ware of the present invention.

Sanitary Ware As shown in FIG. 1A, sanitary ware according to one embodiment of the present invention includes at least a ceramic body 10 and a glaze layer 20 containing yttrium as an antiviral agent formed on the surface thereof.

The sanitary ware 1 according to one embodiment of the present invention may further comprise one or more additional glaze layers between the ceramic body 10 and the glaze layer 20 containing the antiviral agent (yttrium). For example, according to one embodiment of the present invention, as shown in FIG. 1B, the sanitary ware 1 comprises the ceramic body 10, a glaze layer 30 formed on the surface of the ceramic body 10, and a glaze layer 20 containing the antiviral agent formed on the surface of the glaze layer 30. In the present invention, the glaze layer 30 is sometimes referred to as the base glaze layer, and the glaze layer 20 is sometimes referred to as the antiviral glaze layer. The base glaze layer 30 is not particularly limited and may be a glaze layer that is typically applied to ceramic bodies.

The ceramic body 10 is not particularly limited and may be a conventionally known ceramic body. That is, it may be a sanitary ware body slurry prepared from silica sand, feldspar, clay, or the like, which is appropriately shaped.

Glaze Layer In the present invention, the glaze layer 20 contains, as its components, an antiviral agent and a glaze material that can achieve the surface properties described below together with the antiviral agent.

Antiviral Agent In the present invention, the antiviral agent is yttrium (Y).

The yttrium contained in the glaze layer 20 inactivates viruses adhering to the surface of the glaze layer. According to a preferred embodiment of the present invention, yttrium (Y ³⁺ ) that is dissolved on the surface of the glaze layer and ionized in a chemically stable state inactivates viruses adhering to the surface of the glaze layer. In this way, the glaze layer 20 can exhibit practical antiviral properties.

In the present invention, the antiviral properties of sanitary ware equipped with a glaze layer 20 containing yttrium can be expressed as an index of antiviral activity against bacteriophage Qβ. The antiviral activity value can be determined, for example, by the following test method in accordance with ISO 21702.

<Antiviral test method>
0.4 mL of the virus solution is dropped onto a test piece (a sanitary ware test piece with a glaze layer containing yttrium, and a control (a sanitary ware test piece with a glaze layer that does not contain an antiviral agent)), and the test piece is covered with a film.
- Leave the test piece at 25°C for 24 hours.
After leaving it to stand, the virus on the test piece is washed and collected, and then the virus infectivity is measured.
- Calculate the antiviral activity value using the following formula to evaluate the antiviral properties.
R = Ut - At
R: antiviral activity value Ut: common logarithm of the virus infectivity (PFU/cm ² ) of the control after standing for 24 hours At: common logarithm of the virus infectivity (PFU/cm ² ) of the test piece of sanitary ware provided with a glaze layer containing yttrium after standing for 24 hours

In the present invention, the antiviral activity of sanitary ware equipped with a glaze layer 20 containing yttrium can be expressed as an index using the antiviral activity value (V) determined in accordance with JIS R1756 Visible Light B Conditions (Bright). Specifically, an antiviral test is conducted using bacteriophage Qβ in accordance with JIS R1756 Visible Light B Conditions. A 20W white fluorescent lamp (Toshiba Lighting & Technology Corporation, "Neoline" FL20S/W) is used as the light source, and visible light of 380 nm or greater is irradiated at an illuminance of 500 lux through a UV-cut filter (Nitto Jushi Kogyo Co., Ltd., N-169). The illuminance is measured using an IM-5 illuminometer manufactured by Topcon Corporation. The antiviral activity value (V) in bright light was calculated using the following formula, assuming a visible light irradiation time of 4 hours.

Antiviral activity value: V = Log ₁₀ (UV/TV)
TV: bacteriophage infectivity titer (pfu) of sanitary ware with a glaze layer containing yttrium after light irradiation
UV: bacteriophage infectivity titer (pfu) per control after light irradiation
As a control, sanitary ware with a glaze layer that does not contain the antiviral agent will be used.

In the present invention, the glaze layer 20 containing yttrium has an antiviral activity value of 2 to 6. An antiviral activity value of 2 or higher meets the practical antiviral performance standards for sanitary ware.

In the present invention, in order to exhibit practical virus activity, the amount of yttrium eluted from the surface of the glaze layer 20 is preferably at least about 0.05 ppm.
In a preferred embodiment of the present invention, the amount of yttrium dissolved is approximately 1 to 2% of the yttrium content contained in a region 10 nm deep from the surface of the glaze layer toward the ceramic body (the direction of the arrow shown in Figure 1).

In the present invention, it is sufficient that the glaze layer 20 contains yttrium, and the content thereof is not particularly limited. However, in a preferred embodiment of the present invention, the content of yttrium contained in the glaze layer 20 is 2 wt% or more, calculated as yttrium oxide ( _{Y2O3 )} , when the total of the yttrium constituting the glaze layer 20 and the other glaze materials described below is taken as 100 wt%. By containing 2 wt% or more of yttrium, calculated as _yttrium oxide ( _Y2O3 ), the glaze layer ₂₀ can exhibit practical antiviral properties. It goes without saying that the amount of yttrium oxide ( _Y2O3 ) can be stoichiometrically converted to the weight percentage of yttrium.

In another preferred embodiment of the present invention, the content of yttrium contained in the glaze layer 20 can be quantified by analyzing the glaze layer 20 by X-ray fluorescence spectroscopy (XRF). In the present invention, the atomic abundance (mass%) of yttrium contained in the glaze layer 20 is determined using a scanning X-ray fluorescence analyzer (Rigaku ZSX Primus IV (manufactured by Rigaku Corporation)) under the following measurement and analysis conditions.
(Measurement conditions)
Tube voltage: 60 kV
Tube current: 50mA
Measurement depth: Several tens of μm (about 0 to 50 μm)
Measurement area: Φ20mm
(Analysis conditions)
La detection line: La Lα (alpha) line, 2θ=82.88
Spectroscopic crystal: LiF (200)
Detector: SC
The above scanning X-ray fluorescence analyzer has a measurement limit of a region from the surface (0 μm) of the glaze layer 20 to a depth of approximately 50 μm in the direction of the ceramic body (the direction of the arrow shown in FIG. 1 ). Therefore, in the present invention, the quantification of yttrium using the above scanning X-ray fluorescence analyzer identifies the glaze layer 20 by determining the yttrium content (mass %) in a region from the surface of the glaze layer 20 to a depth of approximately 50 μm.

The amount of yttrium atoms measured by X-ray fluorescence spectroscopy (XRF) has the advantage that it is possible to accurately measure the amount of yttrium contained in a region extending from the surface (0 μm) of the glaze layer 20 to a depth of approximately 50 μm toward the ceramic body, i.e., the amount of yttrium contained in the vicinity of the surface of the glaze layer 20.
That is, the yttrium content in terms of yttrium oxide, as already explained, represents the yttrium content (percentage) in the entire glaze layer 20, and the yttrium content measured by X-ray fluorescence analysis (XRF) pinpoints and accurately represents the yttrium content near the surface of the glaze layer 20. Furthermore, the yttrium content measured by X-ray fluorescence analysis (XRF) is useful for accurately determining, based on stoichiometry, the amounts of various compounds, such as yttrium oxide and chloride, to be added as starting materials for the antiviral agent.

Other Glaze Materials Glaze layer 20 includes materials typically used in glazes, such as SiO ₂ , Al ₂ O ₃ , divalent metal oxides, and monovalent metal oxides, along with yttrium.
According to a preferred embodiment of the present invention, the weight percentage of _SiO2 relative to the glass component is 52 to 76%, the weight percentage of _Al2O3 relative to the _glass component is 6 to 14%, the weight percentage of divalent metal oxide relative to the glass component is 11.4 to 27.6%, and the weight percentage of monovalent metal oxide relative to the glass component is 1.5 to 6.5%.

The glaze layer 20 is mainly composed of _SiO2 , _Al2O3 , _divalent metal oxides, and monovalent metal oxides, but may also contain _Fe2O3 , _TiO2 , _{V2O5 , etc.} As divalent metal oxides, alkaline earth metal oxides such as _CaO and MgO, ZnO, CuO, etc. As monovalent metal oxides, _Na2O , _K2O , _Li2O , etc. can be used.

In the present invention, preferred compositions of glaze materials other than yttrium are, for example, as shown in Table 1 below.

State of Presence of Yttrium (Antiviral Agent) in Glaze Layer 20 In the present invention, yttrium is preferably present in an amorphous (non-crystalline) state at least on the surface of the glaze layer 20. By having yttrium present in an amorphous state on the surface of the glaze layer 20, the yttrium can be efficiently ionized and eluted onto the surface of the glaze layer, making it possible to efficiently inactivate viruses adhering to the surface of the glaze layer. Furthermore, because yttrium is present in an amorphous state, it is possible to reduce the impact on the surface properties of the glaze layer surface.

In the present invention, it is more preferable that yttrium exists in a vitrified state on at least the surface of the glaze layer 20. By having yttrium in a vitrified state on the surface of the glaze layer 20, the yttrium can be more efficiently ionized and eluted onto the surface of the glaze layer, making it possible to more efficiently inactivate viruses adhering to the surface of the glaze layer. Furthermore, because the yttrium exists in a vitrified state, the impact on the surface properties of the glaze layer surface can be reduced.

The fact that yttrium is present in an amorphous (non-crystalline) state, preferably in a vitrified state, at least on the surface of the glaze layer 20 can be confirmed by XRD measurement of the surface of the glaze layer 20. For example, an XRD device, X'Pert PRO manufactured by PANalytical, is used to perform the measurement under the following conditions, and if no peak is observed, it is confirmed that the glaze layer is not crystalline, that is, is in an amorphous (non-crystalline) state, preferably in a vitrified state.
XRD measurement conditions Measurement range: 3° to 60°
Scan rate: 4°/min
Applied voltage: 45 V, applied current: 40 mA

In the present invention, it is even more preferable that yttrium undergoes spinodal phase separation at least on the surface of the glaze layer 20. In the present invention, "spinodal phase separation" generally refers to a state in which particle precipitation due to crystallization in the glaze layer is suppressed, resulting in the effect that the specific lanthanoid is more likely to leach out stably onto the surface of the glaze layer, and even if the specific lanthanoid is present on the surface of the glaze layer, its impact on the surface properties of the glaze layer is further reduced. In particular, with regard to leach-out, spinodal phase separation of yttrium on the surface of the glaze layer 20 allows yttrium to stably ionize and leach out from the surface of the glaze layer, making it possible to more efficiently inactivate viruses adhering to the surface of the glaze layer and exhibiting high antiviral properties.

As described below, spinodal phase separation of yttrium is achieved by firing the ceramic body 10 and the glaze that forms the glaze layer 20 together once, followed by cooling. Specifically, by firing the ceramic body 10 and the glaze that forms the glaze layer 20 together once and then cooling, it is possible to induce glass phase separation. Glass phase separation is a phenomenon in which single-phase glass separates into multiple phases. When glass consisting of multiple components exists in a homogeneous liquid phase (molten glass), as the temperature decreases, there exists a region where the free energy is lower in a two-phase mixture state than in a single-phase state. Molten glass in such a region separates into two phases because it is thermodynamically more stable when separated into two phases.

In the present invention, a glaze composed of multiple components such as SiO ₂ , metal oxides, and yttrium oxide is converted into a uniform (single) glass liquid phase (glass melt) by firing. This glass melt is placed in a metastable immiscible region by cooling to a temperature below the liquidus line in the glass phase equilibrium diagram. The metastable immiscible region includes (i) a binodal region in which the glass melt undergoes phase separation through a nucleation-growth mechanism in which nuclei are generated and grow, and (ii) a spinodal region in which the glass melt becomes thermodynamically unstable and undergoes phase separation without nucleation (spinodal decomposition mechanism). In the binodal region, one of the two phases formed by phase separation exists as a dispersed spherical particle that is not entangled with the other, while in the spinodal region, one of the two phases formed by phase separation exists as a dispersed non-spherical particle that is highly entangled with the other. Theoretically, yttrium can be in both a spinodal phase-separated state and a binodal phase-separated state in the glaze layer. In the present invention, by integrally firing the ceramic body 10 and the glaze for forming the glaze layer 20 and cooling them, it is possible to make yttrium abundant near the surface of the glaze layer, and to make the proportion of yttrium present near the surface of the glaze layer in the spinodal phase-separated state higher than the proportion of yttrium present in the binodal phase-separated state, although the details of the mechanism are not clear. This has been confirmed by experiments, as will be described later. For example, as shown in Figure 3, yttrium is abundant near the surface of the glaze layer 20, and this yttrium is present in the spinodal phase-separated state.

The forms in which yttrium exists in a spinodal phase separation state near the surface of the glaze layer are believed to include states in which the yttrium-rich phase is entangled with a non-yttrium-rich phase (-Si-O- structure), or states in which the yttrium-rich portion is more entangled with the non-yttrium-rich portion (i.e., more uniformly present at higher resolution), as well as states in which the yttrium-rich portion cooperates with other portions in the glass matrix structure of the glaze layer surface to form an entangled structure as a whole. The presence of yttrium near the surface of the glaze layer in such a state is believed to enable or promote the macroscopically uniform elution of yttrium from the glaze layer surface, resulting in high antiviral properties.

The present invention requires that regions where yttrium has undergone spinodal phase separation exist on the surface of the glaze layer 20 within the scope of the effects of the present invention. This does not exclude situations where regions where yttrium has undergone binodal phase separation exist at a lower ratio than regions where yttrium has undergone spinodal phase separation, for example, due to unavoidable circumstances in the manufacturing process of the glaze layer 20, as long as the effects of the present invention are not impaired.

Furthermore, because yttrium is present on the surface of the glaze layer 20 in a spinodal phase separation state, scattering at the interface between the two phases causes the glaze layer to appear white, making it possible to achieve a glaze layer surface with excellent image clarity, as described below. In addition, because yttrium is present on the surface of the glaze layer 20 in a spinodal phase separation state, an yttrium-rich phase is uniformly present on the surface, allowing yttrium to be stably eluted, resulting in high antiviral properties.

surface texture
Average roughness (Ra)
In the present invention, the glaze layer 20 preferably has a surface roughness (Ra) of less than 0.07 μm. A surface roughness (Ra) of less than 0.07 μm makes it difficult for urinary stones, mold, yellowing, and other stains to adhere to the sanitary ware, and even if they do adhere, they can be easily removed with a weak water flow. As a result, the surface of the sanitary ware can be maintained clean for a long period of time without requiring frequent cleaning operations.

According to a preferred embodiment of the present invention, Ra is 0.068 μm or less, more preferably 0.05 μm or less, and even more preferably 0.04 μm or less. In this case, the resistance to adhesion of dirt and the ease of removal are further improved.

In this invention, "surface roughness (Ra)" refers to the centerline average roughness (μm) measured using a stylus-type surface roughness measuring device (JIS-B0651) and defined in JIS-B0601 (1994).

In the present invention , the glaze layer 20 preferably has a DOI value of 80 or more on its surface as measured by a Wave-Scan DOI measuring device. In the present invention, the "DOI value" refers to a DOI value measured by a Wave-Scan DOI measuring device, such as the Wave-Scan DIO (orange peel measuring device) manufactured by BYK Gardner (Germany). In the present invention, the DOI value is used as an index representing the image clarity of the surface of the glaze layer provided on the sanitary ware according to the present invention. "Image clarity" refers to the clarity of the reflection of objects. This appearance quality is determined by the difference in light reflection depending on the surface shape of the glaze layer, and is perceived by the human visual sense.

A DOI value of 80 or higher on the surface of the glaze layer 20 gives the viewer an impression of excellent image clarity, resulting in the sanitary ware having a luxurious feel. Furthermore, good image clarity makes stains on the sanitary ware more noticeable, allowing for early detection of the adhesion of filth, including viruses, and thus preventing the adhesion of filth, etc. from being left unattended. According to a preferred embodiment of the present invention, the DOI value of the surface of the glaze layer 20 is 85 or higher.

The Wavescan DOI measuring device moves a laser point source across the surface of the glaze layer, scanning it, measuring the brightness/darkness of the reflected light point by point at set intervals, just like the human eye, to detect the optical profile of the glaze layer's surface. This optical profile is then passed through a frequency filter for spectral analysis, allowing the structure of the glaze layer's surface to be analyzed. Microwave scanning using the device involves irradiating the glaze layer surface with laser light from the laser point source at an angle of 60° from the perpendicular, and the detector measuring the reflected light at the same angle but opposite to the perpendicular. The characteristic spectrum of the device is as follows:
du: wavelength 0.1 mm or less Wa: wavelength 0.1 to 0.3 mm
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 0.3 mm or less Here, DOI is a parameter consisting of du, Wa, and Wb, and is expressed as DOI=f(du, Wa, Wb).

Color Difference: ΔE* Value In the present invention, the glaze layer 20 preferably has a surface color difference: ΔE* value of 1.20 or less. A ΔE* value of 1.20 or less on the surface of the glaze layer 20 allows for the production of sanitary ware with excellent light resistance. The ΔE* value is measured by conducting a weathering test using a sunshine carbon arc lamp weathering tester (S-300, manufactured by Suga Test Instruments Co., Ltd.) in accordance with the sunshine carbon arc lamp method described in Chapter 9, Section 8 of JIS K5400 (1990). The test time is 8 hours, and the L*, a*, and b* values of the photocatalyst-coated body before and after the test are measured using the SCE method to determine the color difference: ΔE* = [(ΔL*) ² + (Δa*) ² + (Δb*) ² ] ^1/2 . A color difference meter (CR-400, manufactured by Konica Minolta, Inc.) can be used as the color difference meter.
The color difference ΔE* value of the surface of the glaze layer 20 is more preferably 0.8 or less, and even more preferably 0.7 or less.

In the present invention, the thickness of the glaze layer 20 is preferably 50 to 1200 μm, more preferably 100 to 800 μm, and even more preferably 150 to 400 μm. The glaze layer 20 having such a thickness can achieve the above-mentioned surface texture.

Manufacturing Method The sanitary ware according to the present invention can be preferably manufactured by the following method.

First, a ceramic base 10 is prepared. The ceramic base 10 may be a conventionally known sanitary ceramic base slip prepared from raw materials such as silica sand, pottery stone, or clay, which has been appropriately molded.

A glaze slurry for forming the glaze layer 20, that is, a glaze slurry containing an yttrium compound as a raw material for the antiviral agent and other glaze materials, is prepared. The composition of the glaze materials other than the yttrium compound is, for example, as shown in Table 1 above.
Furthermore, as the yttrium compound, for example, a compound having a boiling point of 1000° C. or higher, such as an oxide of yttrium, can be used, more preferably a compound having a boiling point of 1300° C. or higher and a melting point of 1000° C. or higher. Even more preferably, the compound has a melting point of 1000° C. or higher and is water-insoluble.

The glaze slurry for forming the glaze layer 20 can be prepared, for example, as follows.
Embodiment 1
A glaze material having the composition shown in Table 1, water, and a dispersion medium (e.g., alumina balls) are placed in a ceramic pot and pulverized, for example, using a ball mill to obtain a glaze slurry precursor. An yttrium compound is added to this glaze slurry precursor, and the mixture is mixed and pulverized to obtain a glaze slurry for forming the glaze layer 20.
Embodiment 2
A glaze material having the composition shown in Table 1 is melted at a predetermined temperature and cooled to obtain a frit raw material. A yttrium compound is added to this frit raw material, and water, a dispersion medium, and other raw materials (e.g., pottery stone, ZnO, etc.) are further added as needed. The mixture is placed in a ceramic pot and pulverized, for example, by a ball mill to obtain a glaze slurry for forming the glaze layer 20.

According to a preferred aspect of the present invention, in the above-mentioned Embodiments 1 and 2, it is preferable that the average particle size of the yttrium compound after pulverization is approximately the same as the average particle size of the glaze material after pulverization (including other raw materials in Embodiment 2). For example, it is preferable that the average particle sizes of the yttrium compound and the glaze material are approximately the same, being 10 μm or less, preferably approximately 6 to 7 μm. Here, the average particle size refers to the so-called 50% particle size in particle size distribution data measured by laser diffraction. Furthermore, "approximately the same" average particle size means that the ratio of the average particle size of the yttrium compound to the average particle size of the glaze material (former/latter) is within the range of 0.9 to 1.1.

By aligning the average particle size of the yttrium compound and the glaze material in this way, it is possible to cause spinodal phase separation of the yttrium on the surface of the glaze layer 20, and to achieve the above-mentioned surface properties (Ra, DOI value, ΔE* value).

Next, the glaze slurry for forming the glaze layer 20 is applied to the surface of the ceramic body 10. There are no particular restrictions on the application method, and any commonly used method such as spray coating or dip coating can be used as appropriate.

Next, the ceramic body 10 to which the glaze slurry for forming the glaze layer 20 has been applied is fired. That is, the ceramic body 10 and the glaze slurry are fired together. The firing temperature is preferably a temperature at which the sanitary ware body sinters and the glaze softens, and is also lower than the melting point of yttrium. Such a firing temperature is preferably between 1000°C and 1300°C, and more preferably between 1150°C and 1250°C. It is preferable to perform the firing together only once. The inventors have experimentally confirmed that performing the firing together only once suppresses the crystallization of yttrium. Specifically, they have confirmed that multiple firings cause crystals to precipitate from the amorphous layer of the glaze layer; for example, performing a second firing at a temperature lower than the first firing temperature causes crystals to precipitate.

The resulting fired body is then cooled. The cooling conditions are not particularly limited, and natural cooling may be used, or the temperature and time may be appropriately controlled.

The ceramic body 10 and a glaze slurry prepared so that the average particle size of the yttrium compound is approximately the same as that of the other glaze materials are fired together once at a temperature lower than the melting point of yttrium, and then cooled. This suppresses crystallization of the yttrium, and preferably vitrifies it, more preferably produces a glass liquid phase (glass melt), even more preferably causes phase separation of the glass melt, and most preferably causes spinodal phase separation. As a result, a glaze layer 20 can be obtained whose surface is rich in regions where yttrium has undergone spinodal phase separation.

The present invention will be specifically explained based on the following examples, but the present invention is not limited to these examples.

Preparation of Pottery Body: Pottery body slurry prepared from raw materials such as silica sand, feldspar, and clay was used to prepare 70 mm x 150 mm plate-shaped test pieces.

Preparation of Glaze Slurry for Forming Base Glaze Layer 2 kg of glaze material having the composition shown in Table 2 below, 1 kg of water, and 4 kg of alumina balls were placed in a 6 L ceramic pot, and the mixture was pulverized in a ball mill so that the particle size of the glaze slurry after pulverization measured using a laser diffraction particle size distribution analyzer would be 65% of particles less than 10 μm and 50% of particle sizes would be about 6.5 μm, thereby obtaining a glaze slurry for forming a base glaze layer.

Preparation of Glaze Slurry for Forming Antiviral Glaze Layer: 2 kg of glaze material having the composition shown in Table 3 below, 1 kg of water, and 4 kg of alumina balls were placed in a 6 L ceramic pot and pulverized in a ball mill so that the particle size of the glaze slurry after pulverization measured using a laser diffraction particle size distribution analyzer was 65% ≤ 10 μm and the 50% particle size (D50) was 6.5 μm. Yttrium oxide was added to this glaze slurry precursor in amounts of 1 wt%, 2.5 wt%, 5 wt%, and 10 wt% (i.e., 1 wt%, 2.5 wt%, 5 wt%, and 10 wt% relative to the total content of the glaze material, 100 wt%), and the mixture was pulverized in a ball mill so that the particle size was 65% ≤ 10 μm and the 50% particle size (D50) was 6.5 μm. The antiviral glaze slurries for sanitary ware of Examples 1 to 4 were prepared. Furthermore, a glaze slurry for sanitary ware of Comparative Example 1 was prepared in the same manner as above, except that 5% by weight of cerium oxide was added instead of 5% by weight of yttrium oxide.

The glaze slurries for Examples 1 to 4 prepared as described above were spray-coated onto the ceramic body test pieces. After that, the pieces were fired once together at 1,200°C in a kiln and cooled to produce the sanitary ware of Examples 1 to 4 and Comparative Example 1.

Evaluation Examples The sanitary wares of Examples 1 to 4 and Comparative Example 1 were evaluated as follows.

Content of Antiviral Agent The yttrium content, based on the amount converted to yttrium oxide, contained in the glaze layers of the sanitary ware of Examples 1 to 4 is calculated as 1 wt%/(100 wt% + 1 wt%) × 100 ≒ 0.99%, as the percentage of yttrium oxide (1 wt%) relative to the total (101 wt%) of 100 wt% of the glaze material and 1 wt% of yttrium oxide shown in Table 3. The same applies to Examples 2 to 4 and Comparative Example 1.

Antiviral Activity The antiviral activity value against bacteriophage Qβ was determined by the following test method in accordance with ISO 21702.
0.4 mL of the virus liquid was dropped onto the sanitary ware of Examples 1 to 4, Comparative Example 1, and a control sanitary ware whose glaze layer did not contain an antiviral agent, and then the sanitary ware was covered with a film.
Each piece of sanitary ware was left standing at 25°C for 24 hours.
After leaving the samples to stand, the viruses on each piece of sanitary ware were washed and collected, and the virus infectivity was measured.
- The antiviral activity value was calculated using the following formula.
R = Ut - At
R: antiviral activity value Ut: common logarithm of the viral infectivity (PFU/cm ² ) of the control sanitary ware after standing for 24 hours At: common logarithm of the viral infectivity (PFU/cm ² ) of the sanitary ware of Examples 1 to 4 and Comparative Example 1 after standing for 24 hours The antiviral activity values of the sanitary ware of Examples 1 to 4 and Comparative Example 1 are shown in Table 4.
Furthermore, the amounts of yttrium eluted from the sanitary ware of Examples 1 to 4 were 0.015 ppm, 0.037 ppm, 0.051 ppm, and 0.1 ppm, respectively.
Average roughness (Ra)
The center line average roughness (μm) defined in JIS-B0601 (1994) was determined using a stylus surface roughness measuring device (JIS-B0651). The results are shown in Table 4.

DOI value : Wave-Scan DOI measuring device: The DOI value was measured using a Wave-Scan DIO (orange peel measuring device) manufactured by BYK Gardner (Germany). The results are shown in Table 4.

The results shown in Table 4 confirm that the sanitary ware of Comparative Example 1, which contained Ce, had low antiviral activity and poor surface properties (Ra value and DOI value), whereas the sanitary ware of Examples 1 to 4 all had higher antiviral activity and better surface properties (Ra value and DOI value) than Comparative Example 1. In other words, it was confirmed that the sanitary ware of the present invention combines antiviral properties with excellent stain resistance and easy stain removal properties, and that these properties are exhibited synergistically.

Confirmation of the state of yttrium near the surface of the glaze layer <XRD measurement>
XRD device: X'Pert PRO manufactured by PANalytical was used, and measurements were carried out under the following conditions.
XRD measurement conditions Measurement range: 3° to 60°
Scan rate: 4°/min
Applied voltage: 45 V, applied current: 40 mA
Figure 2 shows the XRD pattern of the glaze layer of the sanitary ware of Example 3. As shown in Figure 2, no peaks were observed in the XRD measurement of the surface of the antiviral glaze layer containing yttrium (4.76 wt%), confirming that yttrium was present in an amorphous (non-crystalline) or vitrified state on the surface of the antiviral glaze layer.

<SEM observation, TEM observation>
The presence of yttrium near the surface of the antiviral glaze layer was observed using SEM and TEM. SEM observations were performed using an S4800 (Hitachi High-Technologies Corporation) under conditions of 50,000x magnification, 2.0 kV applied voltage, and 20 mA applied current (2.0 mm x 50.0 k SE (U, LA100)). TEM observations were performed using an H-9500 (Hitachi High-Technologies Corporation) under conditions of 100,000x magnification and 200 kV applied voltage (MST-20-113310 ID No. 4448c). SEM and TEM images are shown in Figures 3A and 3B. In Figure 3A, the white areas indicate the presence of yttrium, and the black areas indicate the Si-O structure. In Figure 3B, the black areas indicate the presence of yttrium, and the white areas indicate the Si-O structure. The black areas that resemble boundary lines indicate a rich presence of yttrium. The image area above the black boundary line is an air area and is therefore not subject to observation.
3A and 3B, it was confirmed that yttrium was present in abundance near the surface of the antiviral glaze layer, that this yttrium underwent spinodal phase separation, and that the amount of spinodal phase separation of this yttrium was abundant.

Light resistance (discoloration prevention ability)
A weathering test was carried out using a sunshine carbon arc lamp weathering tester (manufactured by Atlas, USA) in accordance with JIS K5400-9-8 Sunshine Carbon Arc Method. The test time was 8 hours, and the L*, a*, and b* values of the photocatalyst-coated body before and after the test were measured using the SCE method to determine the color difference: ΔE* = [(ΔL*) ² + (Δa*) ² + (Δb*) ² ] ^1/2 . A colorimeter (CR-400, manufactured by Konica Minolta, Inc.) was used as the colorimeter. The results are shown in Table 4.

1 sanitary ware, 10 ceramic base, 20 (top) glaze layer, 30 base glaze layer

Claims (9)

A sanitary ware comprising a ceramic body and a glaze layer formed on the surface of the ceramic body,
The glaze layer contains 2% by weight or more of yttrium in terms of yttrium oxide (Y ₂ O ₃ ) when the total of the yttrium constituting the glaze layer and the glaze materials other than the yttrium is taken as 100% by weight, and has an antiviral activity value of 2 or more as determined by the following [Test Method] in accordance with ISO 21702,
A sanitary ware characterized in that yttrium is present in an amorphous (non-crystalline) state at least on the surface of the glaze layer.
[Test method]
0.4 mL of bacteriophage Qβ solution was dropped onto the sanitary ware described above, and onto a control sanitary ware whose glaze layer did not contain an antiviral agent, and then covered with a film. Each sanitary ware was left standing at 25°C for 24 hours. After leaving it standing, the bacteriophage Qβ on each sanitary ware was washed out and recovered, and the viral infectivity was measured. The antiviral activity value was calculated using the following formula: R = Ut - At
R: antiviral activity value Ut: common logarithm of the viral infectivity (PFU/cm ² ) of the control sanitary ware after standing for 24 hours At: common logarithm of the viral infectivity (PFU/cm ² ) of the sanitary ware after standing for 24 hours. 2. The sanitary ware according to claim 1 , wherein the glaze layer has a surface roughness (Ra) of 0.07 μm or less. 3. The sanitary ware according to claim 1 , wherein the glaze layer has a surface with a DOI value of 80 or more as measured by a Wavescan DOI measuring device. The sanitary ware according to any one of claims 1 to 3 , wherein the yttrium undergoes spinodal phase separation at least on the surface of the glaze layer. The sanitary ware according to any one of claims 1 to 4 , further comprising a base glaze layer between the ceramic body and the glaze layer. A method for manufacturing the sanitary ware according to any one of claims 1 to 5 ,
The process of preparing the pottery base,
preparing a glaze slurry containing yttrium and glaze materials other than the yttrium;
applying the glaze slurry to the surface of the ceramic body;
and firing the pottery body to which the glaze slurry has been applied to form a glaze layer. 7. The method of claim 6 , wherein the calcination is carried out at a temperature below the melting point of yttrium. 8. The method according to claim 6 , wherein the ratio of the average particle size of the yttrium to the average particle size of the glaze material (the former/the latter) is in the range of 0.9 to 1.1. The method according to any one of claims 6 to 8 , further comprising the step of forming a base glaze layer on the surface of the ceramic body, and applying the glaze slurry to the surface of the base glaze layer.