JP7700517B2 - Sanitary ware - Google Patents

Description

The present invention relates to sanitary ware, and more specifically to sanitary ware having good antiviral properties.

In order to ensure a hygienic surface and to ensure the appearance design of sanitary ware, a glaze layer is formed on the outermost surface. To improve hygiene, a technology has been proposed in which an antibacterial agent is added to the glaze layer. For example, CN111393188A (Patent Document 1) discloses a sanitary ware that includes a base glaze layer and a top glaze layer that contains a nano-silver antibacterial agent.

In addition, examples of imparting antiviral properties to composite oxides have been reported. WO2020/017493A1 (Patent Document 2) suggests that composite oxide ceramics containing rare earth elements and other specific metal elements have both water repellency and antibacterial and 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, FIG. 8).

In Patent Document 2, although no comparison with single oxides is confirmed, it is disclosed that calcined powder (500°C, 400°C, or 550°C) of composite oxide ceramics (LMO, LWO, LCMO (LMO with part of the La replaced with cerium (Ce)), LMWO (LMO with part of the Mo replaced with W)) containing lanthanum (La) and/or tungsten (W) shows activity against bacteriophages Qβ and Φ6 (Figures 11, 14-17, 20).

In addition, Cosmetology Research Report Vol. 28, 2020, pp. 43-52 (Non-Patent Document 1), written by the inventor of Patent Document 2, discloses the same content as Patent Document 2, and discloses that CeO ₂ shows almost no activity against bacteriophages Qβ and Φ6, whereas La ₂ O ₃ shows a certain level of activity, and that the anti-Qβ and Φ6 activities of La ₂ O ₃ are lower than those of LMO (page 47, second paragraph in the right column, FIG. 7).

On the other hand, there have been reports of liquid compositions that have been given antiviral properties. JP 2020-111546 A (Patent Document 3) proposes an antiviral composition containing a rare earth salt, a zinc salt, and water, and specifically 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., a higher antiviral property, than an aqueous solution lacking either a rare earth salt or a zinc salt. Patent Document 3 discloses that the antiviral composition is processed into fibers and also suggests that it is processed into a coating agent such as a paint, but does not disclose that it is processed into a ceramic material or a glaze material.

To date, there have been no reports of rare earth elements, particularly lanthanum, having practical antiviral properties on their own, and on the other hand, the need for sanitary ware with practical antiviral properties has increased due to the recent COVID-19 pandemic. Furthermore, adding additives to the glaze generally roughens the surface of the sanitary ware, which can be undesirable from the standpoint of stain resistance or design.

CN111393188A publication WO2020/017493A1 publication JP 2020-111546 A

Cosmetology Research Report Vol. 28, 2020, p43-52

The inventors have now experimentally confirmed that by incorporating a specific amount or more of lanthanum into the glaze layer of sanitary ware, the lanthanum alone exhibits practical antiviral properties. The present invention is based on this finding.

Therefore, the present invention aims to provide sanitary ware with a glaze layer that has practical antiviral properties.

The sanitary ware according to the present invention has:
A sanitary ware comprising a ceramic base and a glaze layer formed on a surface of the ceramic base,
The glaze layer is characterized in that it contains lanthanum as an antiviral agent in an amount of 5% by weight or more calculated as lanthanum oxide (La ₂ O ₃ ).
The sanitary ware according to the present invention further comprises:
A sanitary ware comprising a ceramic base and a glaze layer formed on a surface of the ceramic base,
The glaze layer is characterized in that it contains lanthanum as an antiviral agent in an atomic abundance of 9 mass% or more as measured by X-ray fluorescence spectrometry (XRF).

The present invention provides sanitary ware equipped with a glaze layer that has practical antiviral properties.

FIG. 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 XRD patterns of the glaze layers of sanitary ware of Examples 1 to 15 having different lanthanum contents. 1 is a SEM image of the surface of the glaze layer of the sanitary ware of Example 4. 1 is a cross-sectional SEM image of the glaze layer of the sanitary ware of Example 4. The relationship between the amount of lanthanum converted into lanthanum oxide and the amount of lanthanum dissolved onto the surface of the glaze layer is shown. The relationship between the amount of lanthanum eluted and the antiviral activity value is shown. 1 shows the relationship between the amount of lanthanum converted to lanthanum oxide (wt %) and the atomic abundance (mass %) of lanthanum measured by XRF. 1 shows the relationship between the atomic abundance (mass%) of lanthanum measured by XRF and the antiviral activity value. FIG. 1 is an SEM cross-sectional image showing the state of lanthanum in a glaze layer when a glaze containing 10% by weight of lanthanum oxide as a raw material for an antiviral agent was fired under firing condition 1 (1200° C. for a short time). FIG. 13 is an SEM cross-sectional image showing the state of lanthanum in a glaze layer when a glaze containing 10% by weight of lanthanum oxide as a raw material for an antiviral agent was fired under firing condition 2 (1200° C. for medium time). FIG. 13 is an SEM cross-sectional image showing the state of lanthanum in a glaze layer when a glaze containing 10% by weight of lanthanum oxide as a raw material for an antiviral agent was fired under firing condition 3 (1200° C. for a long time).

Definition In this invention, "sanitary ware" refers to ceramic products used around toilets and washrooms, specifically toilet bowls, urinals, toilet strainers, toilet tanks, washstand basins, hand basins, etc. Additionally, "pottery" refers to ceramics whose base is fired to a degree that it is slightly absorbent and whose surface is glazed.

In addition, with respect to the present invention, the phrase "a specific amount or more of lanthanum alone" exhibits practical antiviral properties means that, whereas the composite oxide disclosed in Patent Document 2 exhibits antiviral properties by being composed of lanthanum and other metal elements (Mo, W), and whereas the liquid composition disclosed in Patent Document 3 exhibits antiviral properties by containing a rare earth salt and other metal salt (zinc salt), a specific amount or more of lanthanum itself exhibits practical antiviral properties.

Sanitary Ware As shown in FIG. 1A, the sanitary ware according to the present invention comprises at least a ceramic base 10 and a glaze layer 20 containing a specific amount or more of lanthanum formed on the surface thereof.

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

The pottery body 10 is not particularly limited and may be a conventionally known pottery body. That is, it may be a sanitary ware body slip prepared from raw materials such as silica sand, feldspar, clay, etc., which is appropriately shaped.

Glaze Layer In the present invention, the glaze layer 20 contains, as its components, a specific amount or more of lanthanum as an antiviral agent, and a glaze material that can realize the surface properties described below together with the antiviral agent.

Antiviral Agent In the present invention, the antiviral agent is lanthanum (La).

Content In one embodiment of the present invention, the content of lanthanum contained in the glaze layer 20 is 5% by weight or more in terms of _lanthanum oxide ( _La2O3 ) when the total of _the lanthanum constituting the glaze layer 20 and other glaze materials described below is taken as 100% by weight. By containing 5% by weight or more of lanthanum in terms of lanthanum oxide ( _La2O3 ), the glaze layer 20 can exhibit practical antiviral properties. It goes without saying that the amount of lanthanum oxide can be stoichiometrically converted to the weight % of lanthanum.

In another embodiment of the present invention, the content of lanthanum contained in the glaze layer 20 can also be quantified by analyzing the glaze layer 20 by X-ray fluorescence spectrometry (XRF). In the present invention, the atomic abundance (mass%) of lanthanum 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-mentioned 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 about 50 μm in the direction of the pottery body (the direction of the arrow shown in FIG. 1 ). Therefore, in the present invention, the quantification of lanthanum using the above-mentioned scanning X-ray fluorescence analyzer identifies the glaze layer 20 by the lanthanum content (mass %) in a region about 50 μm deep from the surface of the glaze layer 20.

In this embodiment, the lanthanum content in the region from the surface (0 μm) of the glaze layer 20 to a depth of about 50 μm in the direction toward the ceramic body is 9 mass% or more in terms of atomic abundance measured by X-ray fluorescence analysis (XRF). By containing 9 mass% or more of lanthanum in the above region in terms of atomic abundance measured by X-ray fluorescence analysis (XRF), the glaze layer 20 can exhibit practical antiviral properties.

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

In this specification, the glaze layer 20 containing "a specific amount or more of lanthanum" means that the glaze layer 20 contains 5% by weight or more of lanthanum in terms of lanthanum oxide (lanthanum _oxide : _La2O3 ), or that a region of the glaze layer 20 from the surface (0 μm) of the glaze layer 20 to a depth of approximately 50 μm toward the ceramic body as measured by X-ray fluorescence analysis (XRF) contains 9% by mass or more of lanthanum in atomic abundance.

A specific amount or more of lanthanum contained in the glaze layer 20 efficiently inactivates viruses attached to the surface of the glaze layer. According to a preferred embodiment of the present invention, lanthanum (La ³⁺ ) that is dissolved on the surface of the glaze layer and ionized in a chemically stable state efficiently inactivates viruses attached 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 having a glaze layer 20 containing a specific amount or more of lanthanum can be expressed as an index of antiviral activity value 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 liquid is dropped onto the test pieces (sanitary ware test pieces with a glaze layer containing a specific amount of lanthanum or more, and a control (sanitary ware test piece with a glaze layer that does not contain an antiviral agent)), and then the test pieces are covered with a film.
- Leave the test piece at rest 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 a test piece of sanitary ware having a glaze layer containing a specific amount or more of lanthanum after standing for 24 hours

In the present invention, the antiviral activity of sanitary ware having a glaze layer 20 containing a specific amount or more of lanthanum can be expressed as an index of the antiviral activity value (V) obtained according to JIS R1756 visible light B condition in bright place. Specifically, an antiviral test is performed using bacteriophage Qβ according to JIS R1756 visible light B condition. Using a 20W white fluorescent lamp (Toshiba Lighting & Technology Corporation, "Neoline" FL20S/W) as the light source, visible light of 380 nm or more is irradiated at an illuminance of 500 lux through an ultraviolet cut filter (Nitto Plastics Industry Co., Ltd., N-169). The illuminance is measured using an illuminometer: IM-5 manufactured by Topcon Corporation. The antiviral activity value (V) in bright place can be calculated by the following formula, assuming that the visible light irradiation time is 4 hours.

Antiviral activity value: V = Log ₁₀ (UV/TV)
TV: Bacteriophage infectivity value (pfu) of sanitary ware having a glaze layer containing a specific amount or more of lanthanum after light irradiation
UV: Bacteriophage infectivity (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 a specific amount or more of lanthanum has an antiviral activity value of 2 to 6. An antiviral activity value of 2 or more satisfies the practical antiviral performance standard for sanitary ware.

In the present invention, in order to exhibit practical virus activity, the amount of lanthanum eluted on 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 lanthanum eluted is about 1 to 2% of the lanthanum content in a region extending from the surface of the glaze layer to a depth of 10 nm in the direction toward the ceramic body (the direction of the arrow shown in FIG. 1).

From the viewpoint of practical antiviral properties alone, the upper limit of the lanthanum content in the glaze layer 20 is not particularly limited, but since it is preferable that the glaze layer 20 constituting the outermost layer of the sanitary ware satisfies the surface properties desired for sanitary ware, in the present invention, it is preferable to control the upper limit of the lanthanum content in the glaze layer 20. Details will be described later.

Other Glaze Materials Glaze layer 20 contains materials typically used in glazes, such as SiO ₂ , Al ₂ O ₃ , divalent metal oxides, and monovalent metal oxides, along with a specific amount of lanthanum or more.
According to a preferred embodiment of the present invention, the weight percentage of _SiO2 relative to the glass component is _52-76 %, the weight percentage of _Al2O3 relative to the glass component is 6-14%, the weight percentage of divalent metal oxide relative to the glass component is 11.4-27.6%, and the weight percentage of monovalent metal oxide relative to the glass component is 1.5-6.5%.

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, the preferred composition of glaze materials other than lanthanum with a specific amount or more is, for example, as shown in Table 1 below.

State of existence of lanthanum (antiviral agent) in glaze layer 20 In the present invention, it is preferable that lanthanum exists in an amorphous (non-crystalline) state at least on the surface of the glaze layer 20. By having lanthanum exist in an amorphous state on the surface of the glaze layer 20, lanthanum can be efficiently ionized and eluted on the surface of the glaze layer, and viruses attached to the glaze layer surface can be efficiently inactivated. In addition, since lanthanum exists in an amorphous state, the effect on the surface properties of the glaze layer surface can be suppressed.

According to a preferred embodiment of the present invention, the lanthanum content in the glaze layer 20 is less than 14.2% by weight in terms of lanthanum oxide ( _La2O3 ), or the lanthanum content in a region from the surface (0 μm) of _the glaze layer 20 to a depth of approximately 50 μm toward the ceramic body is less than 21.2% by mass in terms of atomic abundance measured by X-ray fluorescence analysis (XRF), thereby making it possible to suppress the precipitation of crystals (for example, composite crystals of La and Si) in the glaze layer 20.

According to a more preferred embodiment of the present invention, the content of lanthanum contained in the glaze layer 20 is less than 11.5% by weight in terms of lanthanum oxide ( _La2O3 ), or the content of lanthanum contained in a region from the surface (0 μm) _of the glaze layer 20 to a depth of about 50 μm toward the ceramic body is less than 18.9% by mass in terms of atomic abundance measured by X-ray fluorescence analysis (XRF), so that lanthanum can be present in an amorphous state on the surface of the glaze layer 20. In other words, lanthanum can be encapsulated in the amorphous region of the glaze layer 20. In this state, it is possible to bring the surface properties of the glaze layer 20 closer to the desired ones described below.

In the present invention, it is more preferable that lanthanum is present in a vitrified state at least on the surface of the glaze layer 20. By having lanthanum present in a vitrified state on the surface of the glaze layer 20, lanthanum can be more efficiently ionized and eluted on the surface of the glaze layer, making it possible to more efficiently inactivate viruses attached to the surface of the glaze layer. In addition, because it is present in a vitrified state, the effect on the surface properties of the glaze layer surface can be suppressed, making it possible to bring the surface properties of the glaze layer 20 closer to the desirable ones described below.

The fact that lanthanum 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 lanthanum 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 the precipitation of particles due to crystallization in the glaze layer is suppressed, and as a result, the specific lanthanoid is more likely to stably dissolve on the surface of the glaze layer, and even if the specific lanthanoid is present on the surface of the glaze layer, the effect of further suppressing the effect of the specific lanthanoid on the surface of the glaze layer is achieved. In particular, with regard to dissolution, by spinodal phase separation of lanthanum on the surface of the glaze layer 20, lanthanum can be stably ionized and dissolved from the surface of the glaze layer, making it possible to more efficiently inactivate viruses attached to the surface of the glaze layer, and thus exhibiting high antiviral properties.

As described below, spinodal phase separation of lanthanum is achieved by firing the ceramic base 10 and the glaze that forms the glaze layer 20 together once and then cooling them. Specifically, by firing the ceramic base 10 and the glaze for forming the glaze layer 20 together once and cooling them, it is possible to induce the phase separation phenomenon of glass. Phase separation of glass is a phenomenon in which single-phase glass separates into multiple phases. When glass consisting of multiple components exists as a uniform liquid phase (molten glass), there exists a region in which the free energy is lower in a two-phase mixture state than in a single-phase state as the temperature decreases. The 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 consisting of multiple components such as SiO ₂ , metal oxides, and lanthanum oxide becomes 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 phase equilibrium diagram of glass. The metastable immiscible region includes (i) a binodal region in which the glass melt undergoes phase separation by 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 is dispersed in the form of spherical particles that are not entangled with the other, and in the spinodal region, one of the two phases formed by phase separation is dispersed in a nonspherical shape that is highly entangled with the other. Theoretically, lanthanum can be in both a spinodal phase separation state and a binodal phase separation state in the glaze layer, but in the present invention, by integrally firing the pottery body 10 and the glaze for forming the glaze layer 20 and cooling it, it is possible to make lanthanum exist in a rich state near the surface of the glaze layer, and to make the proportion of lanthanum existing in the spinodal phase separation state higher than the proportion of lanthanum existing in the surface of the glaze layer in the binodal phase separation state, although the details of the mechanism are not clear. This has been confirmed by experiments as described later, and, for example, as shown in Figures 3A, 3B, and 6A, lanthanum exists in a rich state near the surface of the glaze layer 20, and this lanthanum exists in a spinodal phase separation state.

The modes in which lanthanum exists in a spinodal phase separation state near the surface of the glaze layer include states in which a lanthanum-rich phase exists intertwined with a phase that is not lanthanum-rich (-Si-O- structure), and states in which lanthanum-rich parts exist more intertwined with parts that are not lanthanum-rich (i.e., exist uniformly with higher resolution), as well as states in which lanthanum-rich parts cooperate with other parts in the glass matrix structure on the surface of the glaze layer to form an entangled structure as a whole. The presence of lanthanum near the surface of the glaze layer in such a state is believed to enable or promote the macroscopic uniform elution of lanthanum from the surface of the glaze layer, resulting in the exertion of high antiviral properties.

The present invention requires that the area where lanthanum has undergone spinodal phase separation is present on the surface of the glaze layer 20 within the scope of the effects of the present invention, and does not exclude an embodiment in which the area where lanthanum has undergone binodal phase separation is present at a lower ratio than the area where lanthanum has undergone spinodal phase separation due to unavoidable circumstances, for example, in the process of manufacturing the glaze layer 20, within the scope of the effects of the present invention.

Furthermore, since lanthanum is present on the surface of the glaze layer 20 in a spinodal phase separation state, scattering at the interface between the two phases results in a white color, making it possible to realize a glaze layer surface with excellent image clarity, as described below. In addition, since lanthanum is present on the surface of the glaze layer 20 in a spinodal phase separation state, a lanthanum-rich phase is uniformly present on the surface, allowing lanthanum to dissolve stably, 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. With a surface roughness (Ra) of less than 0.07 μm, urinary stones, mold, yellowing, and other stains are less likely 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 in a clean state for a long period of time without the need for frequent cleaning operations.

In a preferred embodiment of the present invention, the content of lanthanum contained in the glaze layer 20 is less than 10% by weight in terms of lanthanum oxide (La ₂ O ₃ ), so that the surface roughness (Ra) of the glaze layer 20 can be made less than 0.07 μm.
In another preferred embodiment of the present invention, the lanthanum content in the region extending from the surface (0 μm) of the glaze layer 20 toward the pottery body at a depth of approximately 50 μm is less than 18.5 mass % in terms of atomic abundance as measured by X-ray fluorescence spectroscopy (XRF), thereby making it possible to make the surface roughness (Ra) of the glaze layer 20 less than 0.07 μm.
Therefore, in the present invention, by setting the lanthanum content in the glaze layer 20 to 5% by weight or more _and less than 10% by weight in terms of lanthanum oxide ( _La2O3 ), or by setting the lanthanum content in the region from the surface (0 μm) of the glaze layer 20 toward the ceramic body at a depth of approximately 50 μm, to 9% by mass or more and less than 18.5% by mass in terms of atomic abundance measured by X-ray fluorescence spectrometry (XRF), it is possible to realize a sanitary ware 1 having a glaze layer 20 that combines practical antiviral properties with excellent resistance to adhesion and easy removal of dirt (properties that make it difficult for dirt to adhere and easy to remove).

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 the present invention, "surface roughness (Ra)" refers to the center line average roughness (μm) measured using a stylus surface roughness measuring device (JIS-B0651) and defined by JIS-B0601 (1994).

DOI Value In the present invention, the glaze layer 20 preferably has a DOI value of 80 or more on its surface as measured by a wavescan DOI measuring device. In the present invention, the "DOI value" refers to a DOI value measured by a wavescan DOI measuring device, for example, a 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 of the sanitary ware according to the present invention. "Image clarity" represents the clarity of the reflection of objects, and this appearance quality is determined by the difference in light reflection depending on the surface shape of the glaze layer, and is recognized by human vision.

When the DOI value of the surface of the glaze layer 20 is 80 or more, the viewer is given an impression of excellent image clarity, resulting in the sanitary ware having a luxurious feel. In addition, good image clarity makes dirt adhering to the sanitary ware more noticeable, allowing the adhesion of filth, including viruses, to be detected early, thereby 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 more.

The Wavescan DOI measuring device moves a laser point source over the surface of the glaze layer to scan it, measuring the brightness/darkness of the reflected light point by point at a set interval, like the human eye, to detect the optical profile of the glaze layer surface, and furthermore, this optical profile is spectrally analyzed through a frequency filter to analyze the structure of the glaze layer surface. In the microwave scan using the device, the laser point source irradiates the glaze layer surface with laser light at an angle of 60° from the perpendicular line, and the detector measures the reflected light at the same angle opposite to the perpendicular line. 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 color difference: ΔE* value of its surface of 1.20 or less. When the ΔE* value of the surface of the glaze layer 20 is 1.20 or less, a sanitary ware with excellent light resistance can be obtained. The ΔE* value is measured by carrying out a weather resistance test using a sunshine carbon arc lamp weather resistance tester (manufactured by Suga Test Instruments Co., Ltd., S-300) 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 by the SCE method to obtain the color difference: ΔE* = [(ΔL*) ² + (Δa*) ² + (Δb*) ² ] ^1/2 . A color difference meter (manufactured by Konica Minolta, Inc., CR-400) 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 of such a thickness can achieve the above-mentioned surface properties.

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

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

A glaze slurry for forming the glaze layer 20, that is, a glaze slurry containing a lanthanum compound containing 5% by weight or more of lanthanum in terms of lanthanum oxide ( _La2O3 ) as a raw material for _the antiviral agent, and other glaze materials is prepared. The composition of the glaze materials other than the lanthanum compound is, for example, as shown in Table 1 above. In addition, as the lanthanum compound, for example, a lanthanum oxide or the like having a boiling point of 1000°C or more, more preferably a boiling point of 1300°C or more and a melting point of 1000°C or more can be used. Even more preferably, it is a water-insoluble compound having a melting point of 1000°C or more.

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, by a ball mill to obtain a glaze slurry precursor. A lanthanum compound containing 5% by weight or more of lanthanum calculated as lanthanum oxide ( _La2O3 ) is added to this glaze slurry precursor, _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 prescribed temperature and cooled to obtain a frit raw material. A lanthanum compound containing 5% or more by weight of lanthanum calculated as lanthanum oxide ( _La2O3 ), water, a _dispersion medium, and other raw materials (e.g., pottery stone, ZnO, etc.) as required are added to this frit raw material, and 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 lanthanum after crushing is approximately the same as the average particle size of the glaze material after crushing. For example, it is preferable that the average particle size of the lanthanum and the glaze material is approximately the same, being 10 μm or less, preferably about 6 to 7 μm. Here, the average particle size means the so-called 50% particle size in particle size distribution data measured by the laser diffraction method. In addition, the average particle size being "approximately the same" means that the ratio of the average particle size of the lanthanum to the average particle size of the glaze material (the former/the latter) is in the range of 0.9 to 1.1.

By aligning the average particle size of lanthanum and the glaze material in this way, it is possible to cause spinodal phase separation of lanthanum 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 base 10. There are no particular limitations on the application method, and any general method such as spray coating or dip coating can be appropriately selected and used.

Then, the pottery base 10 to which the glaze slurry for forming the glaze layer 20 has been applied is fired. That is, the pottery base 10 and the glaze slurry are fired together. The firing temperature is preferably a temperature at which the sanitary pottery base sinters and the glaze softens, and is lower than the melting point of the antiviral agent. Such a firing temperature is preferably 1000°C or higher and 1300°C or lower, more preferably 1150°C or higher and 1250°C or lower. It is preferable to perform the firing together only once. The inventors have confirmed through experiments that the crystallization of lanthanum is suppressed by performing the firing together only once. Specifically, it has been confirmed that crystals precipitate from the amorphous layer of the glaze layer when firing is performed multiple times, and that crystals precipitate when the second firing is performed at a temperature lower than the first firing temperature, for example.

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

The ceramic base 10 and the glaze slurry, which has been prepared so that the average particle size of lanthanum is approximately the same as that of the other glaze materials, are fired once together at a temperature lower than the melting point of lanthanum, and then cooled, whereby, while suppressing crystallization of lanthanum, it is preferably vitrified, more preferably converted into a glass liquid phase (glass melt), even more preferably phase-separated from the glass melt, and most preferably spinodal phase-separated, thereby obtaining a glaze layer 20 on whose surface there is an abundance of regions where lanthanum has undergone spinodal phase separation.

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

Preparation of Pottery Base: Pottery base slurry was prepared from raw materials such as silica sand, feldspar, and clay, and a plate-shaped test piece of 70 mm x 150 mm was prepared using the slurry.

Preparation of glaze slurry for forming base glaze layer 2 kg of a 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 pulverized in a ball mill so that the particle size measurement result of the glaze slurry after pulverization using a laser diffraction particle size distribution analyzer showed that 65% of the particles were 10 μm or less and the 50% particle size was 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 ground in a ball mill so that the particle size measurement result of the glaze slurry after grinding using a laser diffraction particle size distribution analyzer was 65% 10 μm or less and 50% particle size (D50) was 6.5 μm, to obtain a glaze slurry precursor. Lanthanum oxide (La ₂ O ₃ ) with different contents shown in Table 4 was added to this glaze slurry precursor (i.e., lanthanoid oxide with each concentration shown in Table 4 was added to the total content of the glaze material 100 wt%), mixed, and ground in a ball mill so that 65% 10 μm or less and 50% particle size (D50) was 6.5 μm, to prepare the antiviral glaze slurries for sanitary ware of Examples 1 to 15.

The antiviral glaze slurries prepared as above were applied to the above-mentioned ceramic base test pieces by spray coating. After that, the pieces were fired once together at 1200°C in a kettle to produce the sanitary ware of Examples 1 to 15.

The sanitary wares of Evaluation Examples 1 to 15 were subjected to the following evaluations.

Lanthanum Content The amounts (wt %) of lanthanum contained in the glaze layers of the sanitary ware of Examples 1 to 15, calculated as lanthanum oxide (La ₂ O ₃ ), and the atomic abundances (mass %) measured by XRF were as shown in Table 4.
The lanthanum content (wt%) of each sanitary ware shown in Table 4, calculated as the amount of lanthanum oxide (La ₂ O ₃ ), for the sanitary ware of Example 4, for example, was calculated as 5 wt%/(100 wt% + 5 wt%) × 100 ≈ 4.8%, which is the percentage of lanthanum oxide (5 wt%) to the total (105 wt%) of 100 wt% of the glaze material and 5 wt% of lanthanum oxide shown in Table 3. The same applies to the other Examples 1 to 3 and 4 to 15.
Comparing the lanthanum content (wt%) based on _the lanthanum oxide ( _La2O3 ) equivalent amount of each sanitary ware with the lanthanum content (mass%) measured by XRF, it was confirmed that the latter was greater. This indicates that the lanthanum content near the surface of the antiviral glaze layer is greater than the lanthanum content in the entire antiviral glaze layer. In other words, it indicates that lanthanum is concentrated near the surface of the antiviral glaze layer.
Therefore, according to the present invention, lanthanum (antiviral agent) can be concentrated near the surface of the glaze layer, and as a result, good antiviral properties can be exhibited. Furthermore, according to the present invention, even a small amount of lanthanum can be concentrated near the surface of the glaze layer, so good antiviral properties can be efficiently exhibited, and since the amount of lanthanum is small, the Si-O structure of the glaze layer is not affected, that is, a sanitary ware in which excellent surface properties are maintained can be realized.
Incidentally, the atomic abundance (mass%) of lanthanum contained in the glaze layers of the sanitary ware of Examples 10 and 11, measured by XRF, is thought to include a measurement error, although the cause is unclear.

Relationship between the content of the antiviral agent (lanthanum), the amount of elution of the antiviral agent, and the antiviral activity value In addition, the relationship between the content of the antiviral agent, the amount of elution of the antiviral agent, and the antiviral activity value in the sanitary ware of Examples 1 to 15 was confirmed.
Fig. 4A shows the relationship between the amount of lanthanum in terms of lanthanum oxide ( _La2O3 ) ( _wt % ₎ and the amount of lanthanum dissolved (ppm) on the glaze layer surface. Fig. 4B shows the relationship between the amount of lanthanum dissolved and the antiviral activity value. Fig. 5A shows the relationship between the amount of lanthanum in terms of lanthanum oxide ( _La2O3 ) (wt%) and the amount of lanthanum atoms present (mass%) measured by XRF. Fig. 5B shows the relationship between the amount of lanthanum atoms present (mass%) measured by XRF and the antiviral activity value.
4 and 5, it was confirmed that a proportional relationship exists between the amount of lanthanum converted to lanthanum oxide (La ₂ O ₃ ) (wt %) and the atomic abundance (mass %) of lanthanum measured by XRF, that a proportional relationship exists between the lanthanum content and the amount of lanthanum eluted onto the glaze layer surface, and that a proportional relationship also exists between the amount of lanthanum eluted and the antiviral activity value.

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 15, and onto sanitary ware in which the glaze layer did not contain the antiviral agent as a control, 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 away and collected, and the viral infectivity was then 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 being left to stand for 24 hours At: common logarithm of the viral infectivity (PFU/cm 2 ) of the sanitary ware of Examples 1 to 15 after being left to stand for 24 hours The antiviral activity values of the sanitary ware of Examples 1 to ¹⁵ are shown in Table 4.

Average roughness (Ra)
The center line average roughness (μm) defined by 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.

From the results of the antiviral properties, Ra values, and DOI values shown in Table 4, it was confirmed that the sanitary ware of Examples 5 to 9, in which the lanthanum content in the glaze layer was 5% by weight or more and less than 10% by weight in terms of lanthanum oxide (La ₂ O ₃ ), or 9% by weight or more and less than 18.5% by weight in terms of the atomic abundance measured by XRF, had both practical antiviral properties and excellent resistance to adhesion of dirt and easy removal properties (the property of being difficult to stain and easy to remove dirt).

Confirmation of the state of lanthanum 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
The XRD patterns of the glaze layer surface of the sanitary ware of Examples 1 to 15, which had different lanthanum contents, were as shown in Figure 2. The percentage of lanthanum (La) in Figure 2 represents the amount of lanthanum oxide added as a raw material, when the total of the glaze materials shown in Table 3 is taken as 100% by weight. No peaks were observed in the XRD measurement of the glaze layer surface of the sanitary ware of Examples 1 to ₁₂ , and therefore it was confirmed that lanthanum was present in an amorphous (non-crystalline) state or a vitrified state on the surface of the antiviral glaze layer, which had a lanthanum content of 1.0 to 11.5% by weight calculated as _lanthanum oxide (La 2 O 3 ). On the other hand, peaks were observed in the XRD measurement of the glaze layer surface of the sanitary ware of Examples 13 to _15. Therefore, it was confirmed that crystals (presumed to be composite crystals of La and Si) were precipitated on the surface of the antiviral glaze layer in which the lanthanum content was 14.2% by weight or more calculated as lanthanum oxide (La ₂ O 3 ), and lanthanum was not present in an amorphous (non-crystalline) or vitrified state.
The maximum peak observed in the XRD pattern of Example 15 is SiO ₂ , the peaks observed at 2θ (10 to 15) are, from left to right, La ₂ Si ₂ O ₇ , La ₂ Si ₂ O ₇ , and SiO ₂ , and the small peaks observed in the XRD patterns of Examples 1 and 4 are noise.

<SEM Observation>
Among the sanitary ware of Examples 1 to 15, the state of lanthanum near the surface of the glaze layer of the sanitary ware of Example 4 was observed by SEM. The SEM observation was performed using an S4800 (manufactured by Hitachi High-Technologies Corporation) under the conditions of a magnification of 50,000 times, an applied voltage of 2.0 kV, and an applied current of 20 mA (2.0 mm x 50.0 k SE (U, LA100)). The SEM images are shown in Figure 3. Figure 3A is a surface SEM image of the glaze layer, and Figure 3B is a cross-sectional SEM image of the glaze layer. In both Figures 3A and 3B, the white parts indicate the presence of lanthanum, and the black parts indicate a Si-O structure. In Figure 3B, the part that looks like a boundary line indicates the state in which lanthanum is present in a rich manner in the white part. The image area above the white part is an air area, and is therefore not subject to observation.
It was confirmed from Fig. 3B that the lanthanum content in the glaze layer of the sanitary ware of Example 4 was about _4.8 wt% in terms of lanthanum oxide ( _La2O3 ), and the atomic abundance measured by XRF was 8.3 mass%, and from the cross-sectional image of Fig. 3B, it was confirmed that lanthanum was present in abundance on the surface of the glaze layer. It was also confirmed that the lanthanum present on the surface of the glaze layer underwent spinodal phase separation, and further that the amount of spinodal phase separation 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 Type. 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 obtain 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 color difference meter. The results are shown in Table 4.

Confirmation of the relationship between firing conditions, spinodal phase separation amount, and antiviral activity value The amount of lanthanum oxide added was 10 wt %, and the antiviral glaze slurry prepared by the above Preparation Example was applied to the above ceramic base test piece by spray coating. After that, it was fired in a kettle under the following conditions 1 to 3 to produce three types of sanitary ware A to C.
Sanitary ware A: Firing condition 1 (firing temperature: 1200°C, total firing time: 10 hours)
Sanitary ware B: Firing condition 2 (firing temperature: 1200°C, total firing time: 15 hours)
Sanitary ware C: Firing condition 3 (firing temperature: 1200°C, total firing time: 20 hours)
The antiviral activity values of the sanitary ware A to C are shown in Table 5 below. In addition, the state of lanthanum present near the surface of the antiviral glaze layer of the sanitary ware A to C is shown in Figures 6A to 6C.

表５、図６Ａ～Ｃから、酸化ランタンの添加量および焼成温度を同一とした条件下において、焼成時間を短く設定して製造した衛生陶器Ａは、高い抗ウイルス性を有し、さらに釉薬層２０の表面付近にランタンがスピノーダル分相し、また分相領域がリッチであることが確認された。一方、設定時間を長く設定した衛生陶器Ｂは、バイノーダル分相とスピノーダル分相が混在しており、衛生陶器Ａに比べて低い抗ウイルス性を有し、さらに設定時間を長く設定した衛生陶器Ｃは、衛生陶器Ａ、Ｂに比べて低い抗ウイルス性を有することが確認された。なお、釉薬層２０の表面付近にランタンなどの特定のランタノイドをスピノーダル分相で存在させる方法は、上述するように粒子径や焼成時間を調整する以外に当業者であれば様々な手法を採用することができる。

From Table 5 and Figures 6A to 6C, it was confirmed that, under the same conditions of the amount of lanthanum oxide added and the firing temperature, sanitary ware A, which was produced by setting the firing time to a short time, had high antiviral properties, and furthermore, lanthanum underwent spinodal phase separation near the surface of the glaze layer 20, and the phase-separated region was rich. On the other hand, it was confirmed that sanitary ware B, which was produced by setting the firing time to a long time, had a mixture of binodal and spinodal phase separation, and had lower antiviral properties than sanitary ware A, and sanitary ware C, which was also produced by setting the firing time to a long time, had lower antiviral properties than sanitary ware A and B. Note that a person skilled in the art can employ various methods to cause a specific lanthanoid such as lanthanum to exist near the surface of the glaze layer 20 in the form of spinodal phase separation, in addition to adjusting the particle size and firing time as described above.

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

Claims (11)

A sanitary ware comprising a ceramic base and a glaze layer formed on a surface of the ceramic base,
The glaze layer contains lanthanum as an antiviral agent in an amount of 5% by weight or more and less than 14.2% by weight in terms of lanthanum oxide (La ₂ O ₃ ),
1. A sanitary ware comprising: a sanitary ware having a porcelain lining; and a sanitary ware having a porcelain lining, the sanitary ware being characterized in that the antiviral agent is present in an amorphous (non-crystalline) state on at least a surface of the glaze layer. A sanitary ware comprising a ceramic base and a glaze layer formed on a surface of the ceramic base,
The glaze layer contains lanthanum as an antiviral agent in an atomic abundance of 9% by mass or more and less than 21.2% by mass as measured by X-ray fluorescence spectrometry (XRF),
1. A sanitary ware comprising: a sanitary ware having a porcelain lining; and a sanitary ware having a porcelain lining, the sanitary ware being characterized in that the antiviral agent is present in an amorphous (non-crystalline) state on at least a surface of the glaze layer. The sanitary ware according to claim 1 or 2, wherein the glaze layer has a surface roughness (Ra) of 0.07 μm or less. The sanitary ware according to claim 3 , wherein the glaze layer contains, as the antiviral agent, lanthanum in an amount of less than 10% by weight calculated as lanthanum oxide (La ₂ O ₃ ). The sanitary ware according to claim 3, wherein the glaze layer contains lanthanum as an antiviral agent in an atomic abundance of less than 18.5% by mass as measured by X-ray fluorescence spectrometry (XRF). The sanitary ware according to any one of claims 1 to 5, characterized in that the glaze layer has a DOI value of 80 or more on its surface as measured by a wavescan DOI measuring device. The sanitary ware according to any one of claims 1 to 6 , wherein the antiviral agent is spinodally separated at least on a surface of the glaze layer. The sanitary ware according to any one of claims 1 to 7, further comprising a base glaze layer between the ceramic base and the glaze layer. A method for producing the sanitary ware according to any one of claims 1 to 8 ,
The process of preparing the pottery base,
A step of preparing a glaze slurry containing a lanthanum compound containing 5% by weight or more _and less than 14.2% by weight of lanthanum in terms of lanthanum oxide ( _La2O3 ) and a glaze material other than the lanthanum compound;
applying the glaze slurry to a surface of the ceramic body;
and firing the pottery body to which the glaze slurry has been applied to form a glaze layer. 10. The method according to claim 9 , characterized in that the ratio of the average grain size of the lanthanum to the average grain 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 9 to 10 , further comprising the step of forming a base glaze layer on a surface of the ceramic body, and applying the glaze slurry to the surface of the base glaze layer.

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