JPH11131261A - Glazed article having photocatalysis function and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glazed article capable of being furnished in various colors and having a photocatalysis function. SOLUTION: The glazed article is the laminate of a substrate 14, a masking layer 16, a colored layer 18 and a photocatalyst bed 20 as the uppermost surface. The thickness of the photocatalyst bed 20 is smaller than the size of an aggregated particle 24 as the aggregate of photocatalyst particles, the upper part of the aggregated particle 24 is projected outward from the surface of a glaze film 22, the lower part is not embedded in the colored layer 18 below the glaze layer 22, and the colored layer 18 is seen on the surface through the glaze film 22 since the aggregated particles are dispersed in the glaze layer 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glaze having a photocatalytic function and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, techniques such as antibacterial and deodorant techniques based on a catalytic reaction of a photocatalyst represented by titanium oxide have been attracting attention. It is generally considered that this photocatalyst receives light having a wavelength of 400 nm or less, that is, ultraviolet energy, to cause a catalytic reaction, thereby activating oxygen in the air and decomposing a decomposition target such as an organic substance.

Therefore, for this photocatalyst to work effectively,
The photocatalyst particles need to be exposed on the surface. If the photocatalyst particles are buried in the holding layer, the light for activating the photocatalysts does not reach the photocatalyst particles, and the photocatalyst particles do not come into contact with air or decomposition objects, and the original function is achieved. This is because it cannot be effective.

In order to make a given product have a photocatalytic function, a binder layer is formed on the surface of a base material of the product, and particles of the photocatalyst are fixed to the surface of the base material via the binder layer. Can be considered.
With this configuration, the photocatalyst particles can be effectively concentrated on the surface, and the photocatalytic function can be effectively exerted.

[0005]

On the other hand, in such a case, the base material itself under the photocatalyst is colored or a colored layer (decorative layer) is formed on the surface of the base material to decorate the product. However, even if an attempt is made to provide various colors, the decoration and the color are covered and covered by the photocatalyst layer (particle group of the photocatalyst). That is, there arises a problem that it is practically impossible to apply various decorations and colorings to the product.

In addition, in this method, the process for forming the photocatalyst layer on the surface of the base material is complicated, which causes a problem that the production cost is increased.

[0007]

The invention of the present application has been made to solve such a problem. Claim 1 relates to a glazed product having a photocatalytic function, comprising a base material and a photocatalyst layer as the outermost layer, wherein the photocatalyst layer has a size larger than the size of secondary particles which are aggregates of photocatalyst particles. A state in which the upper part of the secondary particles protrudes outside from the glaze film surface and the lower part is not buried in a layer below the glaze film in the light-transmitting glaze film having a small thickness. And a layer below the glaze film is contained in a dispersed manner so as to be visible on the surface through the glaze film.

According to a second aspect of the present invention, there is provided a base material and a photocatalyst layer as the outermost layer, wherein the photocatalyst layer comprises photocatalyst particles and one or more of Ag, Cu and Zn in addition to an antibacterial component. And particles of the antimicrobial agent described above are contained in a dispersed state.

According to a third aspect of the present invention, in the second aspect, the photocatalyst layer is formed in a light-transmitting glaze film having a thickness smaller than a size of secondary particles which are aggregates of the photocatalyst particles. The upper part of the secondary particles protrudes outside from the glaze film surface, the lower part is not embedded in the lower layer of the glaze film, and the lower layer of the glaze film is the glaze film. Characterized in that they are contained in a dispersed manner in a state where they can be seen through the surface.

According to a fourth aspect, in any one of the first, second and third aspects, the photocatalyst particles are titanium oxide particles of an anatase type.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a colored layer thicker than the photocatalyst layer is formed below the photocatalyst layer.

According to a sixth aspect, in the fifth aspect, a concealing layer for concealing the surface of the base material is formed below the colored layer and above the base material. I do.

According to a seventh aspect of the present invention, there is provided a method for producing a glaze having a photocatalytic function, comprising a base material and a photocatalyst layer as an outermost layer, wherein the photocatalyst layer is formed of an aggregate of photocatalyst particles. In a translucent glaze film formed thinner than the particle size, the upper part of the secondary particles protrudes from the glaze film surface to the outside, and the lower part is a layer below the glaze film. A method for producing a glazed article, wherein the glazed article is configured to be contained in a dispersed state in a state where the layer is not embedded in the film and the lower layer of the glaze film is visible on the surface through the glaze film, The photocatalyst particles are mixed and dispersed in a glaze slurry for forming a photocatalyst layer, and the glaze slurry containing the photocatalyst particles is reduced in thickness after firing to a thickness of the glaze film smaller than the size of the secondary particles. After being applied to the outermost surface with a thickness, a baking treatment is performed at a temperature equal to or lower than the softening temperature of the base material. The features.

[0014] According to a eighth aspect of the present invention, there is provided a manufacturing method comprising a base material and a photocatalyst layer as an outermost layer. A method for producing a glazed product, wherein the particles of the antibacterial agent as a component are dispersedly contained in a film of the glaze, wherein the photocatalyst particles are contained in a slurry of the glaze for forming the photocatalyst layer. The antibacterial agent particles are mixed and dispersed, and the photocatalyst particles and the antiglare agent-containing glaze slurry are applied to the outermost surface, and then baked at a temperature equal to or lower than the softening temperature of the base material.

According to a ninth aspect of the present invention, there is provided the method according to the eighth aspect, wherein the photocatalyst layer is formed of a translucent glaze having a thickness smaller than a size of secondary particles which are aggregates of photocatalyst particles. The upper part of the secondary particles protrudes outside from the surface of the glaze film, the lower part is not embedded in the lower layer of the glaze film, and the lower layer of the glaze film is the lower part of the glaze film. In producing a glazed product that is configured to be contained in a dispersed manner while being visible on the surface through the film, the thickness of the film of the glazed film after sintering the glaze of the glaze containing the photocatalyst particles and the particles of the antibacterial agent is reduced. It is characterized in that the photocatalyst particles are applied to the outermost surface with a film thickness smaller than the size of the secondary particles which are aggregates.

According to a tenth aspect of the present invention, there is provided a manufacturing method according to the seventh aspect.
9. The method according to any one of 9 to 9, wherein anatase-type titanium oxide particles are used as the photocatalyst particles, and the firing treatment is performed at a temperature of 800 ° C. or less.

The manufacturing method according to claim 11 is the method according to claims 7, 9,
10. In any one of the photocatalytic layers, prior to applying a glaze slurry for forming the photocatalytic layer, first forming a colored layer thicker than the photocatalytic layer below the photocatalytic layer. After applying the slurry of the glaze having a higher fire resistance and a colorant containing the glaze of above, the calcining treatment is performed at a temperature lower than the softening temperature of the base material to form the colored layer, and then the photocatalytic layer is formed. And a baking treatment under a temperature condition at which the colored layer does not soften and melt.

[0018]

According to the first aspect of the present invention, the holding layer of the photocatalyst particles is formed of a translucent glaze film, and the thickness of the glaze is reduced by the aggregate of the photocatalyst particles. Thinner than a certain secondary particle size, with the upper part of the secondary particle protruding outside from the glaze film surface and the lower layer of the glaze film visible through the glaze film In the case of the glazed product according to claim 1, when the product surface is colored, the coloring can be seen through the surface through the outermost photocatalyst layer. The photocatalytic function can be imparted while maintaining good appearance of the product or having various color variations.

In addition, in the case of this glazed product, the glaze film as a holding layer for the photocatalyst particles is thinner than the secondary particles of the photocatalyst particles, and the secondary particles of the photocatalyst particles are retained on the surface of the glaze film. Since it is exposed above, the function as a photocatalyst can be efficiently performed.

According to a second aspect of the present invention, in the glaze film of the photocatalytic layer, particles of an antibacterial agent containing one or more of Ag, Cu, and Zn as antibacterial components are contained in a dispersed state. It is.

When only the photocatalyst particles are contained in the photocatalyst layer, the antibacterial property cannot be favorably performed under the condition not exposed to ultraviolet rays, for example, at night. However, if particles of the antibacterial agent are also contained in the glaze film of the photocatalyst layer according to claim 2, light energy for activating the photocatalyst particles can be obtained even at night when bacteria and the like actively proliferate. The antibacterial action can be favorably performed even in the nighttime when it is not given. Further, in this claim, Ag, C
It has been found that the coexistence of metal ions such as u and Zn with the photocatalyst particles enhances the photocatalytic activity itself, and can effectively perform the antibacterial and deodorant effects in an environment exposed to ultraviolet rays.

According to a third aspect of the present invention, the glaze film of the photocatalytic layer is formed with a thickness smaller than the size of the secondary particles, which are aggregates of the photocatalyst particles, so that the secondary particles protrude from the glaze film surface. If this is the case, the photocatalyst particles can work effectively as in the first aspect.

The above-mentioned antibacterial agent particles have a form in which zeolite, calcium phosphate, zirconium phosphate, silica gel, water-soluble glass, inorganic oxide such as titania, etc. are used as carriers and the carrier carries antibacterial components such as Ag, Cu, Zn and the like. Alternatively, an antibacterial metal or a compound thereof may be used as it is as an antibacterial agent without being supported on such a carrier.

In the glazed product according to claim 2 or 3, the particles of the antibacterial agent contained in the glaze film of the photocatalyst layer do not need to adhere to the surface of the photocatalyst particles. They can exist independently. Also, the particles of the antibacterial agent do not necessarily need to be present only on the surface of the glaze film, and can be dispersed throughout the entire glaze film.

In the present invention, anatase type titanium oxide particles can be suitably used as the photocatalyst particles (claim 4). In the above claims 1, 3 and 4,
The thickness of the glaze film in the photocatalyst layer is, for example, 1 to 30 μm.
m.

According to a fifth aspect of the present invention, a colored layer thicker than the photocatalyst layer is formed below the photocatalyst layer. By forming such a colored layer, the glaze can be colored. The glaze can be colored in various ways by changing the colorant used in the colored layer, and can be exposed on the surface through the photocatalytic layer.

By forming a colored layer thicker than the photocatalyst layer below the photocatalyst layer, the thickness of the photocatalyst layer above the photocatalyst layer, more specifically, the thickness of the glaze film can be easily reduced.

According to a sixth aspect of the present invention, a concealing layer for concealing the surface of the base material is further formed under the colored layer, whereby the color of the base material itself appears on the surface. This can be prevented by the concealing layer, and coloring by the coloring layer can be performed favorably.

According to a seventh aspect of the present invention, in producing the glazed article of the first aspect, photocatalyst particles are mixed and dispersed in a glaze slurry for forming a photocatalyst layer, and the glaze slurry has a thickness of the fired glaze film. Is applied to the outermost surface in a film thickness smaller than the size of the secondary particles of the photocatalyst particles, and then calcined at a temperature equal to or lower than the softening temperature of the base material. The glaze product having the photocatalyst layer on the outermost layer can be easily manufactured by simply applying the glaze slurry to the surface at a predetermined film thickness and then performing the baking treatment.

[0030] In the manufacturing method according to the eighth aspect, the antibacterial agent particles are contained in the glaze slurry together with the photocatalyst particles, and the glaze slurry containing the photocatalyst particles and the antibacterial agent particles is applied to the outermost surface. According to this method, a glaze provided with a photocatalyst layer having both an antibacterial function by an antibacterial agent and a photocatalytic function by photocatalyst particles simply by applying a glaze slurry to the outermost surface and then firing. The product can be easily manufactured.

According to the manufacturing method of the ninth aspect, the glazed article of the third aspect can be easily obtained.

According to a tenth aspect of the present invention, anatase type titanium oxide particles are used as the photocatalyst particles, and firing is performed at a temperature of 800 ° C. or less.

Titanium oxide exhibits a photocatalytic function under an anatase type crystal form, and does not sufficiently exhibit a photocatalytic function under a high temperature type rutile type.

Therefore, in the method of claim 10, firing of the glaze for forming the photocatalyst layer is carried out at a temperature of 800 ° C. or less, whereby the anatase type titanium oxide is converted into rutile type during the firing process. The crystal change can be prevented, and the loss of the photocatalytic function of titanium oxide due to firing can be prevented.

In this case, it is desirable to perform the firing at a temperature of 600 ° C. or higher. If the temperature is lower than this, it is difficult to perform sintering well.

[0036] In the manufacturing method according to the eleventh aspect, a colored layer on the lower side of the photocatalyst layer is first formed, and then, a glaze slurry for forming a photocatalyst layer is applied on the upper side of the colored layer. Under the condition that the colored layer does not soften and melt, the newly applied glaze is baked, so that the outermost photocatalyst layer and the colored layer below it are mixed and diffused by calcination. And both layers can be formed favorably.

[0037]

Next, embodiments of the present invention will be described in detail. FIG.
In the figure, reference numeral 10 denotes an enamel sink as a glazed product according to one embodiment of the present invention, which is provided on a sink 12 and has a stainless plate (1 mm thick in this example) as a base material 14 as shown in FIG. The shielding layer 16, the coloring layer 18, and the photocatalyst layer 20 are laminated on the surface.

The concealing layer 16 is a layer for concealing the surface of the substrate 14, and in this example, is a white layer formed by dispersing titanium oxide particles as a concealing agent in a glaze. In this example, the thickness of the concealing layer 16 is set to 40 μm.

The coloring layer 18 is a layer for coloring the sink 10 and is made of glaze containing a pigment. In this embodiment, the thickness of the coloring layer 18 is 100 μm. On the other hand, the photocatalyst layer 2
Numeral 0 is a layer for imparting a photocatalytic function to the sink 10.
4 is a light-transmitting thin layer having a thickness of 20 μm.

Here, the anatase type titanium oxide particles 24 as the photocatalyst particles have a particle size of 30 μm (the particle size of the secondary particles), and the lower portion is not embedded in the lower colored layer 18 and the upper portion is The photocatalyst layer 20 is held by the glaze film 22 so as to protrude from the glaze film 22 surface.

Hereinafter, a specific production example of the enamel sink 10 having the photocatalytic function will be described in detail. Water was added to a glaze composed of 100 parts by weight of frit A, 20 parts by weight of alumina, and 6 parts by weight of clay to prepare a glaze slurry for the hiding layer 16.

The composition of the frit A is as follows. _{SiO 2 40% B 2 O 3} 14% Na 2 O 7% K 2 O 11% TiO 2 20% NaF 8% ( although the numerical weight%)

Separately, water was added to a glaze consisting of 100 parts by weight of frit A, 6 parts by weight of clay, and 3 to 5 parts by weight of pigment to prepare a glaze slurry for the colored layer 18.

In addition, water was added to a glaze consisting of 100 parts by weight of frit B and 10 parts by weight of anatase-type titanium oxide to prepare a glaze slurry for the photocatalyst layer 20.

The composition of the frit B is as follows. _{SiO 2 50% Al 2 O 3} 4% B 2 O 3 15% Na 2 O 17% K 2 O 3% CaF 2 10% ( although values are% by weight) particle size here anatase type titanium oxide (secondary particles Is 30 μm.

Next, the glaze slurry for the concealing layer 16 and the glaze slurry for the coloring layer 18 prepared above are applied to the surface of the base material 14.
The glaze for the concealing layer 16 and the glaze for the colored layer 18 were applied in this order. At this time, the coating amount of the glaze slurry is determined by the concealing layer 1
The amount of glaze for 6 was 1.5 g per 10 cm ² and the amount of glaze for colored layer 18 was 4 g per 10 cm ² .

Thereafter, they were baked together at 900 ° C. for 5 minutes to form the concealing layer 16 and the colored layer 18 in a laminated manner.
At this time, the thickness of the concealing layer 16 was 40 μm, and the thickness of the coloring layer 18 was 100 μm.

Next, the glaze slurry for the photocatalyst layer 20 prepared above was applied to the surface of the colored layer 18 in an amount of 1 g per 10 cm ² , and then baked at 780 ° C. for about 4 minutes. The photocatalyst layer 20 was formed with a thickness of 20 μm (the thickness of the glaze film 22). And the photocatalytic function was evaluated according to the following method.

That is, as shown in FIG. 3, a test piece 26 cut from the enamel sink 10 was set in a glass cell 28, and a UV lamp 30
(Ultraviolet light), while supplying air containing 0.5 ppm of NO at a flow rate of 1.0 liter / min (relative humidity 60%).
2 and N is measured by a chemiluminescent NO _X meter 34 on the downstream side.
The amount of O was measured, and the photocatalytic function was evaluated.

FIG. 4 shows the result. However, in the figure, (A) shows the measurement results of the example product (anatase type titanium oxide particles 24 held in the photocatalyst layer 20), and (B) does not contain such anatase type titanium oxide particles 24. The measurement result about the comparative example product is shown.

As shown in the results of FIG. 4, in the case of the product of this example, the amount of NO was effectively reduced during UV irradiation, while the anatase type titanium oxide particles were not used. In the case of the comparative example to which no additive was added, the NO amount did not change during UV irradiation, and it can be seen that the photocatalytic function was well exhibited in the case of the present example. Further, in the product of this example, since the photocatalyst layer 20 is translucent and formed to be thin, the colored layer 18 below the photocatalyst layer 20 appears on the surface through the photocatalyst layer 20, The color of the colored layer 18 was well represented on the surface.

Next, in the glaze for the photocatalyst layer 20, Ag particles as antibacterial agents were added together with the anatase-type titanium oxide particles 24 as the photocatalyst particles, and the same treatment as described above was performed. An enamel sink 10 having a laminated structure shown in B) was obtained.

In FIG. 2B, numeral 36 indicates Ag particles, and the anatase type titanium oxide particles 2 as photocatalyst particles.
4 is uniformly dispersed inside the glaze film 22.

Next, a test piece was cut out from the enamel sink 10 thus obtained and subjected to the following antibacterial test. Here, the antibacterial test was carried out according to “Antibacterial Test Method for Antibacterial Products I (1995 Edition) Film Adhesion Method”.

The specific test method is as follows. <Antibacterial evaluation method> 1) Test method A sample (30 mm x 30 mm) was placed in a sterile screw cup (30 mml), and Escherichia coli (Escher) was placed on the test surface of the sample.
ichia coli IFO 3301), Staphylococc
us aureus IFO 12732) and bacterial solutions of methicillin-resistant Staphylococcus aureus IID 1677 were respectively dropped and stored at 37 ° C, and the viable cell count 24 hours after storage was measured. 2) Preparation of bacterial solution The cells of the test bacterium cultured at 37 ° C. for 24 hours on a normal agar slant medium were inoculated into a normal bouillon medium, and cultured with shaking at 37 ° C. for 8 hours. Next, this culture solution was diluted with a phosphate buffered saline, and diluted with a 1/500 concentration ordinary broth medium so that the number of bacteria was 8.0 × 10 ^{5 to} 4.0 × 10 ^6. And 0.05 ml of bacterial solution is dropped on the test surface of the sample,
The storage container was covered and stored in a desiccator at a relative humidity of 90% or more at 37 ° C. for 24 hours, and the viable cell count of the sample was measured. 3) Measurement of viable cell count Specimens were washed out with 5 ml of physiological saline, and the number of viable cells was measured by a pour plate method (cultured at 37 ° C for 24 hours) using a normal agar medium. Was converted to Sterilization rate (%) = ((A−B) / A) × 100 A: Average value of viable cell count of comparative product (Ag-free product) after storage for 24 hours B: This example after storage for 24 hours As a result of the antibacterial test above the average viable cell count of the product, the sterilization rate was 9
9% or more, indicating good antibacterial performance.

The embodiment of the present invention has been described in detail above, but this is merely an example. For example, the present invention is applicable not only to the above-mentioned enameled products, but also to those whose base material is made of ceramics or other materials. Further, the present invention is not limited to the case where the colored layer and the concealing layer are necessarily divided into two layers. It is also possible to use a single layer.

The present invention can be constituted and implemented in various modified forms and modes without departing from the gist of the invention, such as using other particles than the above-mentioned Ag particles as the antibacterial agent particles.

[Brief description of the drawings]

FIG. 1 is a diagram showing an engraved sink according to an embodiment of the present invention installed on a sink.

FIG. 2 is a diagram schematically illustrating a cross-sectional structure of the engraved sink of FIG.

FIG. 3 is a view showing a method of an evaluation test of a photocatalytic function of the product of the example.

FIG. 4 is a diagram showing measurement results obtained by the test method of FIG.

[Explanation of symbols]

 Reference Signs List 14 base material 16 concealing layer 18 coloring layer 20 photocatalytic layer 22 film 24 anatase type titanium oxide particles (photocatalytic particles) 36 Ag particles (antibacterial agent particles)

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01J 35/02 B01J 35/02 J C04B 41/86 C04B 41/86 R // A01N 25/34 A01N 25/34 Z 59/16 59 / 16Z A 59/20 59 / 20Z

Claims (11)

[Claims] Claims: 1. A light-transmitting layer having a substrate and a photocatalyst layer as an outermost layer, wherein the photocatalyst layer is formed to have a thickness smaller than the size of secondary particles that are aggregates of photocatalyst particles. In the glaze film, the upper part of the secondary particles protrudes outside from the glaze film surface, and the lower part is not embedded in the lower layer of the glaze film and the lower layer of the glaze film Characterized in that they are dispersed and contained so that they can be seen on the surface through a film of the glaze. 2. A photocatalyst layer comprising a substrate and a photocatalyst layer as an outermost layer, wherein the photocatalyst layer comprises photocatalyst particles and, in addition, Ag, C
A glazed product having a photocatalytic function, characterized by containing particles of an antibacterial agent containing one or more of u and Zn as antibacterial components. 3. The photocatalytic layer according to claim 2, wherein the secondary particles are formed in a light-transmitting glaze film having a thickness smaller than that of the secondary particles, which are aggregates of the photocatalytic particles. The upper part protrudes outside from the glaze film surface, and the lower part is not embedded in the layer below the glaze film, and the lower layer of the glaze film is exposed through the glaze film. A glazed product having a photocatalytic function, characterized in that it is contained in a dispersed state in a state where it can be seen. 4. The glazed product having a photocatalytic function according to claim 1, wherein the photocatalytic particles are titanium oxide particles of anatase type. 5. The glaze product having a photocatalytic function according to claim 1, wherein a colored layer thicker than the photocatalyst layer is formed below the photocatalyst layer. . 6. The photocatalytic function according to claim 5, wherein a concealing layer for concealing the surface of the base material is formed below the colored layer and above the base material. Glazed products. 7. A light-transmitting material having a base material and a photocatalyst layer as an outermost layer, wherein the photocatalyst layer is formed to have a thickness smaller than the size of secondary particles that are aggregates of photocatalyst particles. In the glaze film, the upper part of the secondary particles protrudes outside from the glaze film surface, and the lower part is not embedded in the lower layer of the glaze film and the lower layer of the glaze film Is a method for producing a glazed product which is contained in a dispersed state in a state where it can be seen through a film of the glaze, wherein the photocatalyst particles are mixed in a glaze slurry for forming the photocatalyst layer. After being dispersed and coated on the outermost surface of the glaze slurry containing the photocatalyst particles with a thickness such that the thickness of the fired glaze film is smaller than the size of the secondary particles, the temperature is lower than the softening temperature of the base material. A method for producing a glazed product having a photocatalytic function, characterized by firing at a temperature. 8. A photocatalyst layer comprising a substrate and a photocatalyst layer as an outermost layer, wherein the photocatalyst layer comprises photocatalyst particles and, in addition thereto, Ag, C
A method for producing a glazed product comprising particles of an antibacterial agent containing one or more of u and Zn as antibacterial components in a state of being dispersed in a glaze film to form the photocatalyst layer. After mixing and dispersing the photocatalyst particles and the antibacterial agent particles in the glaze slurry, and applying the photocatalyst particles and the antibacterial agent-containing glaze slurry to the outermost surface, the temperature is equal to or lower than the softening temperature of the base material. A method for producing a glazed product having a photocatalytic function, characterized by performing a baking treatment. 9. The method according to claim 8, wherein the photocatalyst layer is formed in a translucent glaze film having a thickness smaller than the size of the secondary particles which are aggregates of the photocatalyst particles. The upper part protrudes outside from the glaze film surface, the lower part is not embedded in the layer below the glaze film, and the lower layer of the glaze film is exposed through the glaze film on the surface. In producing a glazed product constituted to be contained in a dispersed state in a visible state, the thickness of the glaze film containing the photocatalyst particles and the antibacterial agent containing the glaze after firing is reduced to an aggregate of the photocatalyst particles. A method for producing a glazed product, characterized in that it is applied to the outermost surface with a film thickness smaller than the size of the secondary particles. 10. The method according to any one of claims 7, 8, and 9,
A method for producing a glazed product having a photocatalytic function, wherein anatase-type titanium oxide particles are used as the photocatalyst particles, and the firing treatment is performed at a temperature of 800 ° C or less. 11. The photocatalyst layer according to claim 7, wherein the thickness of the photocatalyst layer is lower than that of the photocatalyst layer prior to the application of the glaze slurry for forming the photocatalyst layer. For the formation of a thick colored layer, the glaze for the photocatalyst layer is coated with a slurry of a glaze having a higher degree of fire resistance and containing a colorant, and then calcined at a temperature equal to or lower than the softening temperature of the base material. A method for producing a glazed product having a photocatalytic function, comprising forming, then applying a glaze slurry for forming the photocatalyst layer, and baking under a temperature condition at which the colored layer does not soften and melt.