JP2000262905A - Photocatalytic tile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photocatalytic tile capable of making use of the texture or the beauty of the surface of a tiles by providing a photocatalyst in a line like and/or dot-like state on the surface of the tile in the photocatalytic tile provided with the photocatalyst on the surface. SOLUTION: In the photocatalytic tile provided with the photocatalyst on the surface to prevent the soiling of the surface, to impart the self-cleaning function of the surface and to easily remove the soiling to facilitate the cleaning, the photocatalyst is provided in the linear and/or dot-like state. In such a case the photocatalyst is preferably provided so as to expose 40-90% of the surface of the tile. In the case of providing the photocatalyst in the line-like state, the line like state is preferably curved line or mesh-like one. As a result, the photocatalytic reaction is sufficiently advanced even when the surface of the tile is irradiated with light from any direction. As the photocatalyst formed on the surface of the tile, metal oxides such as Zr2O, ZnO2, SnO2, WO3, Bi2O3, SrTiO3, Fe2O3 or the like in addition to TiO2 are mentioned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalytic tile in which a photocatalyst is provided on a tile surface.

[0002]

2. Description of the Related Art For the purpose of preventing the fogging and water droplet formation of a base material by making a surface of a transparent base material such as a mirror, a lens, a plate glass or the like highly hydrophilic, or a building material, a mechanical device or various articles. The surface of the substrate is highly hydrophilized to prevent surface contamination and to provide a self-cleaning (self-cleaning) function of the surface. Formation of a photocatalytic film such as photocatalytic titania (TiO ₂ ) has been performed (Japanese Patent Application Laid-Open No. 9-241038, International Publication W).
O96 / 29375, JP-A-61-83106). A substance having a photocatalytic function such as photocatalytic titania makes the surface of a base material highly hydrophilic by a hydrophilizing effect by photoexcitation, prevents formation of water droplets, and prevents clouding due to light scattering. In addition, dirt containing a large amount of lipophilic component is less likely to adhere, and self-cleaning and action of the surface is obtained, so that the adhered dirt is more easily removed. In addition, NOx and SO
The above effect is also enhanced by promoting the decomposition of x or organic substances.

As a method for forming such a film having a photocatalytic function, JP-A-9-241038 and International Publication WO96 / 29375 describe a sol-gel method by applying and baking a suspension containing TiO ₂ particles. ing. Japanese Patent Application Laid-Open No. 61-83106 describes CVD as a method for forming a film.

[0004]

In the conventional photocatalyst tile, the photocatalyst is formed in a thin film having a uniform thickness as much as possible. It has been found that, when is formed into a thin film of uniform thickness and covers the entire surface of the tile, the unique texture of the glaze layer of the tile may be impaired.

[0005] It is an object of the present invention to provide a photocatalytic tile utilizing the texture or beauty of the background of the tile.

[0006]

According to the present invention, there is provided a photocatalytic tile having a photocatalyst provided on a surface thereof.
The photocatalyst is provided on the tile surface in a linear and / or dot form.

In such a photocatalyst tile, the photocatalyst is provided on the tile surface in a linear and / or dot shape, and a part of the tile surface is exposed. It brings out the texture and beauty.

In the present invention, it is preferable to provide a photocatalyst so as to expose 40 to 90% of the tile surface.

In the present invention, when the photocatalyst is provided linearly,
The linear shape is preferably a curved shape (including a ring shape) or a mesh shape. When the photocatalyst has a curved shape or a mesh shape, the photocatalytic reaction sufficiently proceeds regardless of the direction from which light strikes the tile surface.

[0010]

Embodiments of the present invention will be described below in detail.

In the present invention, the photocatalyst formed on the tile surface includes, in addition to TiO ₂ , ZrO ₂ , ZnO ₂ , Zn
O, SnO ₂ , WO ₃ , Bi ₂ O ₃ , SrTiO ₃ , Fe ₂ O
₃ , metal oxides such as V ₂ O ₅ . One of these metal oxides may be used alone, or two or more thereof may be used in combination. Of these, TiO ₂ is most preferred.

In order to attach the photocatalyst to the tile surface in a linear and / or dot form, an appropriate mask is used, or a photocatalyst forming liquid (solution, suspension, etc.) is applied to the tile surface by a printing screen or the like. After that, it may be dried and fired if necessary.

Without using a mask or a screen, the photocatalyst-forming liquid may be applied to the tile surface in a streak form or sprayed in a scattered manner to adhere the liquid in a linear and / or dot form.

In order to provide a photocatalyst in a curved or mesh form on the tile surface, a foaming agent such as a surfactant is attached to the photocatalyst forming liquid as necessary, and a gas (for example, air) is blown into the liquid. To generate bubbles and adhere the bubbles to the tile surface. In this case, the liquid component constituting the foam remains linearly on the tile surface, and a curved or meshed photocatalytic pattern is formed. When the liquid is an independent spherical bubble, the photocatalyst can be provided in a ring-shaped pattern by attaching the bubble to the tile surface.

When the photocatalyst is provided in a dot or mesh pattern, the photocatalytic function of the tile becomes isotropic, and the same photocatalytic function is exhibited even when light is irradiated from any direction.

On the other hand, for example, in a photocatalyst tile provided with a photocatalyst linearly oriented in one direction, anisotropy may occur in the photocatalytic function depending on the direction of light irradiation.
That is, when the photocatalysts are provided linearly and oriented in one direction, the linear portions of the photocatalysts are arranged in a mountain-like shape extending in one direction. When light is radiated obliquely to this mountain-shaped photocatalyst, light is sufficiently incident on the Sanyo side of the mountain range, and the photocatalytic function is relatively high, but on the San'in side, the amount of irradiated light is small and the photocatalytic function is relatively low. Further, when the light is irradiated along the orientation direction of the mountain range, the light uniformly hits the entire photocatalyst, and a high photocatalytic function is exhibited as a whole.

In view of the above, it is preferable that the photocatalyst tile used for the purpose of always irradiating the light only from a specific direction is provided with the photocatalyst in a dot shape or a mesh shape.

In the present invention, 20 to 90 of the tile surface
It is preferable to provide a photocatalyst such that 50% to 80% is exposed. By providing the photocatalyst in a linear and / or dot form and exposing a part of the background of the tile surface, the original texture or beauty of the tile is not impaired, and the tile design becomes good.

In particular, when the line width is about 0.5 to 2.0 μm or the dot diameter is about 0.5 to 30 μm, the color of the tile glaze is black or dark chromatic. Even so, white streaks and points of the photocatalyst are not visually observed in a pillow-like manner, and the design of the tile is significantly improved.

The adhesion amount of TiO ₂ is 3 to 24 μg per unit area (1 cm ² ) of the tile surface, particularly 6 to 15 μm.
About μg is preferable.

As the liquid for forming the photocatalyst, for example, the following liquids (1) to (3) can be used.

(1) Hydrolyzate or partial hydrolyzate of an organotitanium compound As the organotitanium compound, an alkoxide of titanium, for example, tetraethoxytitanium, tetraisopropoxytitanium, tetra-n-propoxytitanium, tetrabutoxytitanium, Examples include tetramethoxytitanium.
After adding a hydrolysis inhibitor such as hydrochloric acid or ethylamine to this alkoxide and diluting it with an alcohol such as ethanol or propanol, a solution obtained by partially or completely hydrolyzing the hydrolysis is used for forming a photocatalyst. Use as a liquid.

(2) Solution of inorganic titanium compound An aqueous solution of an inorganic compound such as TiCl ₄ and Ti (SO ₄ ) _2, preferably an acidic aqueous solution is exemplified.

(3) Dispersion of titanium oxide fine particles A liquid in which the fine particles are dispersed in water using a dispersant as needed is exemplified. An organic liquid may be used instead of water.

Although the above (1) to (3) relate to TiO ₂ , other components such as SiO ₂ may be further contained.

After the photocatalyst forming liquid is adhered to the tile surface in a linear and / or dot form, it is dried if necessary, and then calcined at 500 to 900 ° C. to crystallize the TiO ₂ component and the tile. It is preferable to fix the glaze on the surface. This crystallization enhances the photocatalytic function. In addition, the glass catalyst glaze adheres to the TiO ₂ component (for example, TiO ₂ fine particles), thereby improving the durability of the photocatalyst.

[0027]

The present invention will be described more specifically below with reference to examples and comparative examples.

Example 1 5 g of titanium tetraisopropoxide, 93 g of water and 2 g of 6N hydrochloric acid were mixed, and 1 g of an anionic surfactant was added as a surfactant, and then air was blown to generate foam. . Take 25 mg of this foam and scoop up the tile (glazed exterior tile manufactured by Inax Corporation. Color tone white. 9.5 ×
(4.5 × 0.7 cm), dried, and then baked at 600 ° C. for 30 min. This resulted in an average of 8 μg of T / cm ² on the tile surface.
A photocatalytic tile to which iO ₂ was attached was obtained.

Observation with a microscope revealed that TiO ₂ having a width of 0.5 μm extended in a mesh pattern on the tile surface. Further, it was recognized that 80% of the tile background was exposed.

The appearance of this tile was exactly the same as the glazed exterior tile to which TiO ₂ was not attached.

The photocatalytic activity of this tile was tested as follows. That is, 5 μl of a 0.01 wt% aqueous solution of methylene blue was dropped on the surface of the tile, dried, and irradiated with an ultraviolet lamp so as to have a UV intensity of ² mW / cm ² . The residual amount of methylene blue on the tile surface is measured over time using a spectrophotometer as the reflectance of blue light, and the irradiation time until the amount becomes half the initial amount (hereinafter, referred to as methylene blue half-life) is measured.

As a result of the test, it was confirmed that the methylene blue half-life of the tile of Example 1 was 60 minutes.

Comparative Example 1 A photocatalytic tile was produced in the same manner as in Example 1, except that about 50 mg of the liquid was brush-coated on the surface of the above-mentioned glazed exterior tile.
As a result, although the methylene blue half-life was not different from about 60 min, an iris phenomenon and a cloudy layer due to light interference were recognized in design.

Example 2 To the liquid of Example 1, 2 g of PVA (polyvinyl alcohol) as a thickener was added and kneaded to form a paste, which was printed in dot form on the surface of the interior tile by screen printing. The size (diameter) of the dots in the printed pattern was 20 μm, and the number of dots was 120,000 per cm ² . This tile has 60% of its surface exposed.

Otherwise, a photocatalytic tile was manufactured in the same manner as in Example 1. This tile was also exactly the same in appearance as a glazed exterior tile to which no TiO ₂ was attached.

The methylene blue half-life of this tile was 40 minutes.

[0037]

As is clear from the above embodiments, according to the present invention, a photocatalytic tile having the original texture and aesthetics and excellent design can be provided.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yuichiro Aihara 5-1-1 Koiehonmachi, Tokoname-shi, Aichi Prefecture Inax Corporation (72) Inventor Toru Onuki 5-1-1 Koiehonmachi, Tokoname-city, Aichi Prefecture Inax Corporation (72) Inventor Yoshio Kamiya 5-1-1 Koie Honcho, Tokoname-shi, Aichi Prefecture Inax Co., Ltd. (72) Inventor Hideo 5-1-1 Koie Honcho, Tokoname-shi, Aichi F-Term (Inax Co., Ltd.) 2K009 BB01 CC03 EE00 EE05 4F100 AA21A AD00B AR00A BA02 BA10A BA10B DC21A GB07 JL06 JL08A 4G069 AA11 BA48A BB04A BC50B EA11 FB23

Claims (4)

[Claims] 1. A photocatalytic tile having a photocatalyst provided on a surface thereof, wherein the photocatalyst is provided linearly and / or dotwise on the tile surface. 2. The photocatalytic tile according to claim 1, wherein the photocatalyst is provided so as to expose 40 to 90% of the tile surface. 3. The photocatalytic tile according to claim 1, wherein at least a part of the photocatalyst is provided in a curved shape. 4. The photocatalytic tile according to claim 1, wherein at least a part of the photocatalyst is provided in a mesh pattern.