JP2001122679A - Antifouling tile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that in the case of forming a surface layer containing photocatalyst particles on the surface of a tile, the coloring happens by photoreduction reaction of iron when the surface layer is brought into contact with the water containing iron ions. SOLUTION: The photoreduction capacity of the surface layer on the surface of the tile expressing hydrophilicity is restrained by irradiating with an ultraviolet ray or the like. Concretely, the tile is immersed in the water containing 2 ppm iron ion and the change of color difference ΔE is made to satisfy the inequality: ΔE<=1 when the surface layer is irradiated with the light having the energy higher than the band gap energy of the photocatalyst particles under such a condition that the photon density per unit time is 1×1015/sec.cm2 and the accumulated photon density is 8×1019/cm2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to tiles.

[0002]

2. Description of the Related Art Conventionally, it has been considered that the surface of a member is made water-repellent to make it difficult for dirt to adhere thereto. However, when water repellency is imparted, muddy water or the like remains on the surface of the base material as water droplets, and when the water dries, it becomes difficult to drop. Further, black streak-like stains become noticeable over time on tiles and the like attached to the outer wall. The dirt is made of a hydrophobic substance such as carbon black as a combustion product, and the hydrophobic substance is more easily adjusted to a hydrophobic base material than water, so that the dirt is not easily washed away by rainwater and stays on the material surface.

In recent years, it has been proposed in the literature ("Polymer", Vol. 44, 1995) that a hydrophilic resin coating is applied to the surface of a substrate to exhibit an automatic cleaning effect. That is, by making the surface of the base material hydrophilic, a thin water film is formed on the surface to make it difficult for dirt components to adhere and to easily wash off dirt with rainwater or the like.

[0004] Therefore, it has been proposed to paint a building with a hydrophilic graft polymer (Chemical Industry Daily Report 19).
January 30, 1995). Further, recently, a large number of hydrophilic paints such as acrylic resins and acrylic silicone resins are commercially available.

Examples of the hydrophilic paint include acrylic silicone resin, aqueous silicone coating agent, graft polymer of silicone resin and acrylic resin, block polymer of silicone resin and acrylic resin, acrylic resin, acrylic-styrene resin, and sorbitan fatty acid ethylene. There are crosslinked urethanes composed of oxides, urethane acetates, sorbitan fatty acid esters, polycarbonate diols and / or polyisocyanates, and crosslinked polyalkylacrylates.

[0006]

As described above, even when the surface of a base material is made hydrophilic by resin coating, the contact angle with water is reduced to at most only about 30 to 40 °, which is a general problem. It is larger than the contact angle (about 20 °) of water on the tile surface, and the effect of automatic cleaning is not higher than that of the tile.

[0007] Further, since the combustion products and city dust are basically hydrophobic, when the contact angle of the substrate with water increases, it tends to adhere to the surface of the substrate exhibiting the same hydrophobicity, and contaminants become conspicuous. Become like In addition, dirt such as combustion products and sludge other than municipal dust exhibits hydrophilicity with a contact angle with water of about 20 ° to 50 °. Therefore, when the contact angle of the substrate surface with water is 20 ° to 50 °, the substrate surface and the dirt exhibit similar hydrophilicity, and the dirt is easily adhered and shows a peak value of the dirt.

On the contrary, the contact angle of the substrate surface with water is 20 ° or less, preferably 10 ° or less, more preferably 1 ° or less.
When the temperature is less than or equal to °, the affinity for water is higher than the affinity for inorganic substances (dirt), and the water that preferentially adheres to the surface inhibits the adhesion of the inorganic substance and also adheres or tries to adhere. Inorganic substances can be easily washed away with water, but no technique has been developed for keeping the contact angle of the substrate surface with water at 10 ° or less for a long time.

On the other hand, JP-A-6-278241 and JP-A-7-51646 propose a method of decomposing dirt by an oxidation-reduction action of a photocatalyst. The decomposition action of the photocatalyst particles based on the oxidation-reduction reaction is such that, when the photocatalyst particles are irradiated with ultraviolet light or the like, electron-hole pairs are generated by photoexcitation, and the electrons reduce surface oxygen to generate superoxide ions (O ²⁻ ). The generated holes oxidize the surface hydroxyl groups to generate hydroxyl radicals (.OH), and the odor attached to the surface by the oxidation-reduction reaction of these highly reactive active species ( ^O2- and .OH). It decomposes components and the like.

[0010]

SUMMARY OF THE INVENTION According to the present invention, in order to impart the property that dirt does not easily adhere to the surface of the member and to give the member itself a self-cleaning effect on the dirt, the contact angle with water is made higher than that of making the surface water-repellent. The fact that it is more effective to make small hydrophilic. In addition, the present inventors have found that photocatalytic particles such as titanium oxide have a function of hydrolyzing (super-hydrophilizing) the surface of an article in addition to a function of decomposing dirt and the like by a conventionally known oxidation-reduction reaction. Have made the present invention based on the facts that have been independently found.

[0011] Here, hydrophilizing action of the photocatalyst present inventors have newly findings recently, its rationale is not fully understood, hydroxyl by photocatalytic effect (OH ^-)
Is chemically adsorbed on the surface of the photocatalyst particles, or a hydroxyl group (O
H ^-) is replaced with an organic group, further the hydroxyl (OH ^-) water molecules in the air is physically adsorbed, the hydrophilic surface is increased by physically adsorbed water increases, super hydrophilic surface is achieved I think that.

As a specific example, a case where the surface layer is made of a silicone resin having a Si ^— O bond will be described. Before irradiating the photocatalyst particles with light, as shown in FIG. R), the surface layer shows hydrophobicity, but when irradiated with light having an energy higher than the band gap energy of the photocatalyst particles, first, as shown in FIG. (R) a hydroxyl group - the substitution (chemisorption), further the hydroxyl ^(OH) - exhibit hydrophilic water molecules in the air are physically adsorbed ^(OH).

Also, titanium oxide (Ti) is used as photocatalyst particles.
O ₂ ) will be described. The state shown in FIG. 2A before the light irradiation is changed to the state shown in FIG. 2A when the light is irradiated, as shown in FIG. 2B. hydroxyl group constituting the (OH ^-) is a Ti atom, a hydrogen atom (H ⁺⁾ is chemically adsorbed to the oxygen atom (O), further the hydroxyl - water molecules and in the air a hydrogen atom (H ^{+) (OH)} Exerts hydrophilicity by physical adsorption.

In the above description, it is clear that the decomposing action of the substance is completely different from the hydrophilizing action. However, in a specific example, even in the case of TiO ₂ , the anatase-type TiO ₂ can undergo oxidation-reduction reaction. However, rutile type TiO ₂ hardly exhibits a substance decomposing action based on a redox reaction. Also, among the photocatalysts, tin oxide does not show a decomposition effect of a substance based on a redox reaction. In these photocatalyst particles, the energy level of the conduction band is not sufficiently high, so that the reduction reaction does not proceed. As a result, the electrons excited by the photoexcitation in the conduction band become excessive, and the electron-hole pairs generated by the photoexcitation are oxidized and reduced. It is believed that they recombine without participating in the reaction. However, both rutile TiO ₂ and tin oxide exhibit a hydrophilizing action. Further, the photocatalytic layer needs to have a thickness of at least 100 nm in order to exhibit the decomposing action of the substance. From these facts, it can be said that the decomposition action of the substance by the photocatalyst and the hydrophilization action are completely different.

As described above, the photocatalyst decomposes substances due to electron-hole pairs generated by photoexcitation. When the surface layer containing such a photocatalyst comes into contact with water containing iron ions. This causes a photoreduction reaction of iron which may occur due to transfer of less electrons, and the member is colored. That is, the redox action of the photocatalyst particles has the advantage of decomposing the dirt component, but also has the disadvantage of coloring the member.

Therefore, in the antifouling tile according to the present invention, a surface layer made of photocatalytic particles or a surface layer containing photocatalytic particles is formed on the tile surface, and this surface layer impairs the hydrophilicity of the surface layer. Suppress the photoreduction ability of the surface layer without
Alkali metal, alkaline earth metal, alumina, silica,
At least one of zirconia, antimony oxide, amorphous titanium oxide, hydrous titanium oxide, aluminum, and manganese
A seed material is added, and the surface layer exhibits hydrophilicity by irradiating light having an energy higher than the band gap energy of the photocatalyst particles, and changes the photoreducing ability of the surface layer by a color difference change (ΔE). When the member is immersed in water containing 2 ppm of iron ions, light having an energy higher than the band gap energy of the photocatalyst particles is applied to the surface layer at a photon density per unit time of 1 × 10 ¹⁵ / sec · cm ² . Under the following conditions, ΔE ≦ 1 when 8 × 10 ¹⁹ / cm ² irradiation was performed at an integrated photon density.

One means for suppressing the photoreducing ability is to reduce the amount of photocatalyst per unit area. As described above, the redox reaction and the hydrophilizing action of the photocatalyst are different actions, and the redox reaction requires a large amount of photocatalyst particles per unit area, but the hydrophilizing action is exerted even with a small amount of the photocatalytic particles. You. For this reason, the content of the photocatalyst particles is preferably 10 μmol / cm ² or less per unit area. By doing so, only the hydrophilizing action can be selected.

Other means for suppressing the photoreducing ability include:
For example, at least one of an alkali metal, an alkaline earth metal, alumina, silica, zirconia, antimony oxide, amorphous titanium oxide, hydrous titanium oxide, aluminum and manganese is added to the surface layer itself, or an underlayer of the surface layer Alternatively, it is added to the coating layer formed on the surface layer.

In the present invention, a color difference change (ΔE) was selected as an index indicating how much the photoreducing ability was suppressed. Specifically, the member is immersed in water containing 2 ppm of iron ions, and light having an energy higher than the band gap energy of the photocatalyst particles is applied to the surface layer at a photon density per unit time (p) of 1 × 10 ¹⁵ / sec. · cm ² become the condition, color difference change when the 8 × 10 ¹⁹ / cm ² were irradiated with integrated photon density (P) (ΔE) was set to be 1 or less.

Here, the photon density (p) per unit time is represented by p = (A · λ) / (h · c).
Here, A is ultraviolet illuminance (W / cm ² ), λ is ultraviolet wavelength (cm), h is Planck's constant, and c is light speed (cm / sec).
c) When there is a wavelength distribution, p = Σ (Ai · λ
i) / (h · c). Where Ai is the wavelength λ
The illuminance of i.

On the other hand, the integrated photon density (P) is P =
It is represented by (A · λ · t) / (h · c). Where t
Is the irradiation time (sec) of the ultraviolet ray. When there is a wavelength distribution, p = Σ (Ai · λi · t) / (h · c)
Is represented by

Titanium oxide is most preferable as the photocatalyst particles. In addition, ZnO, SnO ₂ , SrTiO ₃ ,
Metal oxides such as WO ₂ , Bi ₂ O ₂ , and Fe ₂ O ₂ are mentioned. It is considered that, since a metal element and oxygen are present on the surface, a hydroxyl group (OH ⁻ ) is easily adsorbed on the surface, and therefore, it is easy to exhibit hydrophilicity.

Titanium (titanium oxide) will be described as an example of a method for forming a hydrophilic surface layer containing photocatalyst particles. For example, formation of amorphous titania, application of silica-containing titania, application of tin oxide-containing titania, and application of titania Application of a silicone paint and the like can be mentioned.

The formation of amorphous titania is a method in which a surface to be coated is first coated with amorphous titania, which is baked to change the phase into crystalline titania, and any of the following methods can be employed. . (1) Hydrolysis of organic titanium compound and dehydration polymerization An alkoxide of polycondensed titanium, for example, tetraethoxytitanium, tetraisopropoxytitanium, tetra-n-propoxytitanium, tetrabutoxytitanium, tetramethoxytitanium, or a hydrochloride such as hydrochloric acid or ethylamine After adding a decomposition inhibitor and diluting with an alcohol such as ethanol or propanol, the mixture is applied after partially or completely promoting the hydrolysis, and then the mixture is applied, and the temperature is from room temperature to 200 ° C. And dry. By drying, the hydrolysis of the alkoxide of titanium is completed to form titanium hydroxide, and a layer of amorphous titania is formed by dehydration-condensation polymerization of titanium hydroxide. Instead of titanium alkoxides, other organic titanium compounds such as titanium chelates or titanium acetate may be used. (2) Formation of amorphous titania by inorganic titanium compound An inorganic titanium compound, for example, TiCl ₄ or Ti (SO ₄ ) ₂
Is applied and dried at a temperature of 100 to 200 ° C. to carry out hydrolysis and dehydration-condensation polymerization to form an amorphous titania layer. Or it may form a layer of amorphous titania on the surface to be coated by chemical vapor deposition of TiCl _4. (3) Formation of amorphous titania by sputtering A target of metal titanium or titanium oxide is irradiated with an electron beam in an oxidizing atmosphere to form a layer of amorphous titania on the surface to be coated.

The application of the silica-containing titania is to form a layer comprising a mixture of titania and silica on the surface to be coated. The ratio of silica to the total of titania and silica is 5 to 90 mol%, preferably 10 to 70 mol%, more preferably 10 to 50 mol%. The following method can be employed for forming the surface layer made of silica-containing titania. (1) A suspension containing particles of anatase type or rutile type titania and particles of silica is applied to a surface to be coated, and fired at a temperature equal to or lower than the softening point of the substrate (object to be coated). (2) Based on a mixture of a precursor of amorphous silica (for example, tetraalkoxysilane such as tetraethoxytitanium, tetraisopropoxytitanium, tetran-propoxytitanium, tetrabutoxytitanium, tetramethoxytitanium, etc.) and crystalline titania sol After applying to the surface of the material and hydrolyzing as needed to form silanol, heating at a temperature of about 100 ° C. or more and subjecting the silanol to dehydration polycondensation, the titania is bound with amorphous silica. Obtained surface layer (photocatalytic coating). In particular, if the dehydration condensation polymerization of silanol is performed at a temperature of about 200 ° C. or higher, the degree of polymerization of silanol can be increased, and the alkali resistance performance of the photocatalytic coating can be improved. (3) Dispersing silica particles in a solution of amorphous titania precursor (organic titanium compound such as alkoxide, chelate or acetate of titanium, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) Is applied to the surface of the base material, and the titanium compound is cooled to room temperature for 20 minutes.
By subjecting it to hydrolysis and dehydration polycondensation at a temperature of 0 ° C.,
A thin film of amorphous titania in which silica particles are dispersed is formed. Next, the amorphous titania is changed into crystalline titania by heating to a temperature higher than the crystallization temperature of titania and lower than the softening point of the substrate. (4) Amorphous titania precursor (organic titanium compound such as alkoxide, chelate or acetate of titanium, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) in a solution of amorphous titania precursor (For example, tetraalkoxysilanes such as tetraethoxytitanium, tetraisopropoxytitanium, tetran-propoxytitanium, tetrabutoxytitanium, tetramethoxytitanium, etc., silanols which are hydrolysates thereof, or polysiloxanes having an average molecular weight of 3000 or less) And apply to the surface of the substrate. Next, these precursors are subjected to hydrolysis and dehydration condensation polymerization to form a thin film composed of a mixture of amorphous titania and amorphous silica. Next, the amorphous titania is changed into crystalline titania by heating to a temperature higher than the crystallization temperature of titania and lower than the softening point of the substrate.

The application of titania containing tin oxide is to form a layer made of a mixture of titania and tin oxide on the surface to be coated. The ratio of tin oxide to the total of titania and tin oxide is 1 to 95 mol%, preferably 1 to 50 mol%. The following method can be adopted as a method for forming a surface layer made of titania mixed with tin oxide. (1) A suspension containing particles of anatase type or rutile type titania and particles of tin oxide is applied to a surface to be coated, and fired at a temperature equal to or lower than the softening point of the substrate (object to be coated). (2) Dispersion of tin oxide particles in a solution of a precursor of amorphous titania (organic titanium compound such as titanium alkoxide, chelate or acetate, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) The resulting suspension is applied to the surface of the substrate, and the titanium compound is heated to room temperature for 20 minutes.
By subjecting it to hydrolysis and dehydration polycondensation at a temperature of 0 ° C.,
A thin film of amorphous titania in which tin oxide particles are dispersed is formed. Next, the amorphous titania is changed into crystalline titania by heating to a temperature higher than the crystallization temperature of titania and lower than the softening point of the substrate.

For the application of the titania-containing silicone coating, a coating in which titania (photocatalyst particles) is dispersed in a film-forming element made of uncured or partially cured silicone (organopolysiloxane) or a silicone precursor is used. . Specifically, after the above coating material is applied to the surface of the base material, and after the film-forming element is cured, when the photocatalyst is photoexcited, the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by the action of the photocatalyst. Then, the contact angle of the surface with water becomes close to 0 °, and the surface becomes hydrophilic (super-hydrophilic). This method can cure the film forming element at a relatively low temperature, and can be applied as many times as necessary,
In addition, there is an advantage that it can be easily made hydrophilic even by sunlight. The following resins can be used as the resin. Methyltrichlorosilane, methyltribromosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltri-t-butoxysilane, ethyltrichlorosilane, ethyltribromosilane, ethyltrimethoxysilane, ethyltriethoxysilane, Ethyltriisopropoxysilane, ethyltri-t-butoxysilane, n-propyltrichlorosilane, n-propyltribromosilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltriisopropoxysilane, n-
Propyltri-t-butoxysilane, n-hexyltrichlorosilane, n-hexyltribromosilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-hexyltriisopropoxysilane, n-hexyltrit-butoxysilane, n-decyltrichlorosilane, n-decyltribromosilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n-
Decyltriisopropoxysilane, n-decyltri-t-
Butoxysilane, n-octadecyltrichlorosilane,
n-octadecyltribromosilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octadecyltriisopropoxysilane, n
-Octadecyltri-t-butoxysilane, phenyltrichlorosilane, phenyltribromosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltri-t-butoxysilane, tetrachlorosilane, tetrabromosilane, tetramethoxy Silane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane, dimethyldichlorosilane,
Dimethyldibromosilane, dimethyldimethoxysilane,
Dimethyldiethoxysilane, diphenyldichlorosilane, diphenyldibromosilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenylmethyldichlorosilane, phenylmethyldibromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, triethoxyhydrosilane , Tribromohydrosilane, trimethoxyhydrosilane, isopropoxyhydrosilane, tri-t-butoxyhydrosilane, vinyltrichlorosilane, vinyltribromosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltri-t-butoxysilane, Trifluoropropyltrichlorosilane, trifluoropropyltribromosilane, trifluoropropyltrimethoxysila , Trifluoropropyltriethoxysilane, trifluoropropyltriisopropoxysilane, trifluoropropyltri-t-butoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycid Xypropyltrimethoxysilane, γ
-Glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxysilane, γ-glycidoxypropyltri-t-butoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldi Ethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-
Methacryloxypropyltri-t-butoxysilane, γ
-Aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropyltrit-butoxysilane , Γ-
Mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltriisopropoxysilane, γ-mercaptopropyltri-t-
Butoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, and their partial hydrolysates or mixtures thereof can be used. .

In order to ensure good hardness and smoothness of the silicone resin film, it is preferable to contain 10 mol% or more of the three-dimensional crosslinked siloxane. In order to provide sufficient flexibility of the resin film while securing good hardness and smoothness, it is preferable to contain 60 mol% or less of the two-dimensional crosslinked siloxane. In order to increase the rate at which the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by photoexcitation, use is made of a silicone in which the organic group bonded to the silicon atom of the silicone molecule is an n-propyl group or a phenyl group. Is preferred. An organopolysilazane compound having a silazane bond can be used instead of the silicone having a siloxane bond.

[0029]

(Example 1) Ammonia peptized titanium oxide sol (STS-Ishihara Sangyo)
11) was applied at 5.6 μmol / cm ² and fired at 880 ° C.

(Example 2) On a glazed tile surface, an ammonia-peptized titanium oxide sol (STS-11 manufactured by Ishihara Sangyo) and a silica sol were mixed at a solid content weight ratio of 80:20, and the mixture was 5.6 μmol in amount. / Cm ² , 880 ℃
Was fired.

(Example 3) 10.0 μmol / cm ² of an ammonia-peptized titanium oxide sol (STS-11 manufactured by Ishihara Sangyo) was applied to the surface of a glazed tile and fired at 880 ° C.

(Example 4) 11.2 μmol / cm ² of an ammonia-peptized titanium oxide sol (STS-11 manufactured by Ishihara Sangyo) was applied to the surface of a glazed tile and fired at 880 ° C. Then, a calcium metal concentration of 5 was formed on the titanium oxide film.
An aqueous solution of 0 μmol / g calcium nitrate was applied to fix calcium.

Example 5 A titanium oxide sol of ammonia peptizing type (STS-11 manufactured by Ishihara Sangyo) was applied to the surface of a glazed tile at 11.2 μmol / cm ² and fired at 880 ° C. Thereafter, potassium was fixed in place of calcium of Example 4.

Example 6 A titanium oxide sol of ammonia peptizing type (STS-11 manufactured by Ishihara Sangyo) was applied to the surface of a glazed tile at 11.2 μmol / cm ² and fired at 880 ° C. Thereafter, sodium was fixed in place of the calcium of Example 4.

Example 7 A titanium oxide sol of ammonia peptizing type (STS-11 manufactured by Ishihara Sangyo) was applied to the surface of a glazed tile at 11.2 μmol / cm ² and fired at 880 ° C. Thereafter, magnesium was fixed in place of the calcium of Example 4.

(Example 8) A titanium oxide sol of ammonia peptization type (STS-11 manufactured by Ishihara Sangyo) was applied to the surface of a glazed tile at 11.2 μmol / cm ² and fired at 880 ° C. Thereafter, lithium was fixed in place of calcium of Example 4.

(Example 9) A titanium oxide sol of ammonia peptizing type (STS-11 manufactured by Ishihara Sangyo) was applied to the surface of a glazed tile at 11.2 μmol / cm ² and fired at 880 ° C. Thereafter, zinc was fixed in place of calcium of Example 4.

Example 10 Ammonia-peptized titanium oxide sol (STS-11 manufactured by Ishihara Sangyo Co., Ltd.) on the surface of a glazed tile
Was applied at 1.0 μmol / cm ² and fired at 880 ° C.

(Comparative Example 1) On the surface of a glazed tile, 11.2 μmol / cm ² of an ammonia-peptized titanium oxide sol (STS-11 manufactured by Ishihara Sangyo) was applied and baked at 880 ° C.

Comparative Example 2 A titanium oxide sol of ammonia peptizing type (STS-11 manufactured by Ishihara Sangyo) was applied to the surface of a glazed tile at 11.2 μmol / cm ² and fired at 880 ° C. Thereafter, copper acetate was applied, and B of 0.5 mW / cm ² was applied.
Photoreduction fixation was performed with an LB lamp.

The iron ion coloring property (color difference ΔE), the contact angle with water, the maintenance of the contact angle with water,
The results of tests for the hydrophobic stain removal property and the hydrophilic stain removal property are shown in the following (Table). In addition, iron ion coloring property is 0.5
The change in color difference before and after irradiation with a mW / cm ² BLB lamp for 10 days was measured.

[0042]

【table】

[0043]

As described above, according to the present invention, since a surface layer containing photocatalyst particles is formed on the tile surface, the surface layer exhibits hydrophilicity only by being irradiated with ultraviolet rays or the like. Dirt is less likely to adhere to the surface. In addition, the adhered dirt can be easily removed by washing with water, and a self-cleaning effect that is close to rain can be expected. And according to the antifouling tile of the present invention, the amount per unit area of the photocatalyst particles added to the surface layer is limited, or the photoreduction ability of the surface layer is suppressed without inhibiting the hydrophilicity of the photocatalyst. Since the substance was added,
Hydrophilicity can be maintained while preventing coloring due to reaction with iron ions.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a process of imparting hydrophilicity to the surface of a silicone resin containing photocatalyst particles.

FIG. 2 is a diagram illustrating a process of imparting hydrophilicity to a surface layer made of photocatalytic particles.

Claims (2)

[Claims] 1. A surface comprising photocatalyst particles on a tile surface
A layer or surface layer containing photocatalytic particles is formed,
Photoreduction of surface layer without impairing hydrophilicity of surface layer
Alkali metal, alkaline earth metal,
Lumina, silica, zirconia, antimony oxide, amorphous
Type titanium oxide, hydrous titanium oxide, aluminum, manga
At least one substance is added.
The surface layer is obtained from the band gap energy of the photocatalyst particles.
Even when exposed to high-energy light,
Expressing the photoreduction ability of the surface layer by the color difference change (ΔE),
Immerse the member in water containing 2 ppm iron ions and shine light on the surface layer.
Energy higher than the bandgap energy of the catalyst particles
Of light at a photon density per unit time of 1 × 10 ^Fifteen/ S
ec · cm^Two8 x 1 in integrated photon density
0¹⁹/ Cm^TwoIt is noted that ΔE ≦ 1 when irradiated.
Anti-fouling tiles. 2. The antifouling tile according to claim 1, wherein the photocatalyst particles are titanium oxide, and light having an energy higher than the band gap energy of the photocatalyst particles is ultraviolet light having a wavelength of 400 nm or less. .