JPH1066878A - Photocatalyst body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration irrespective of the kind of backing, to increase the crystallinity, orientation, etc., of a photocatalyst, and to improve photocatalytic activity by providing a substrate film such as a thin metal film and a thin metal oxide film between the backing and a photocatalyst film. SOLUTION: In a photocatalyst body 1, a photocatalyst film 4 is formed on a backing 2 through a substrate film 3. As regards the backing 2, its material and shape are not restricted in particular, and an organic material such as a fabric or nonwoven fabric of a plastic material such as poly(methyl methacrylate) and silicone, synthetic fibers, natural fibers, semisynthetic fibers, etc., an inorganic material such as glass, quartz, ceramics, and silica, a metallic material such as aluminum and stainless steel, and others are used. The substrate film 3 is not restricted particularly, for example, a thin metal film of Ti, Al, Co, etc., and a thin metal oxide film of SiO, SiO2 , BeO, etc., are named. A metal oxide film of TiO2 , ZnO, WO3 , Fe2 O3 , SrTiO3 , etc., is used as the photocatalyst film 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst which is effectively used for water purification, air purification, deodorization, oil decomposition, and the like.

[0002]

2. Description of the Related Art
Metal oxides such as TiO ₂ , ZnO, WO ₃ , Fe ₂ O ₃ , and SrTiO ₃ are widely used as photocatalysts for water purification, air purification, deodorization, oil decomposition, and the like. Such a photocatalyst is usually used in a powder form. In order to fix the powdered photocatalyst, there is a binder fixing method in which, for example, a resin or rubber is mixed and kneaded with a powder as a binder, and the mixture is applied to a base material and sintered at several hundred degrees Celsius. Also, as a method of adhering the photocatalyst to the substrate in a film form, a gel coating film is prepared using a metal alkoxide solution, and a metal oxide film obtained by a sol-gel method of heating it at several hundred degrees Celsius is used as the photocatalyst. It is also known. However, in both the binder fixing method and the sol-gel method, since the metal oxide film is heated at a high temperature as described above, only a heat-resistant base material can be used. On the other hand, if a metal oxide film obtained by a sputtering method is used as a photocatalyst film, a photocatalyst coated with a photocatalyst film can be obtained regardless of the type of the base material. When a substrate of a substance is used, since the substrate and the photocatalyst film are in direct contact, the substrate itself is deteriorated by the photocatalysis, and the substrate is made of amorphous material such as glass (amorphous,
When an (amorphous) material is used, as the photocatalyst film is thinner, the crystallinity and orientation thereof are deteriorated due to the influence of the base material, and the catalytic activity of the photocatalyst film may decrease.

[0003] The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a photocatalyst that is not only excellent in handleability and durability, but also excellent in catalytic efficiency, regardless of the type of substrate to be supported.

[0004]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that a metal thin film or a metal oxide thin film is provided between a substrate and a photocatalytic film. By providing a base film such as the above, regardless of the type of the base material, the deterioration can be prevented, and the crystallinity and orientation of the photocatalytic film can be enhanced, thereby improving the photocatalytic activity. In this case, it is found that, in this case, if a thin film obtained by a sputtering method is used as the base film and the photocatalyst film, the heat resistance of the substrate does not become a problem, and the above object can be more effectively achieved. The present invention has been accomplished.

Accordingly, the present invention provides (1) a photocatalyst characterized in that a photocatalyst film is formed by interposing a base film on a substrate, and (2) the base film is a metal thin film or a metal oxide thin film. The photocatalyst of (1) above, (3) the base film is formed of a metal thin film obtained by performing sputtering using a metal target, or a metal target in an inert gas containing a gas containing oxygen molecules. A metal oxide thin film obtained by performing reactive sputtering, and a photocatalytic film formed by performing reactive sputtering using a metal target in an inert gas containing a gas having oxygen molecules. The photocatalyst according to the above (1) or (2), which is a material film, is provided.

Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a cross-sectional view of a photocatalyst 1 illustrating the configuration of the photocatalyst of the present invention. The photocatalyst 1 is obtained by forming a photocatalyst film 4 on a substrate 2 with a base film 3 interposed therebetween. Here, the material and the shape of the substrate are not particularly limited, and any material may be used as long as it is generally used as a substrate of a photocatalyst. For example, polymethyl methacrylate, polycarbonate, silicone,
Plastic materials such as polystyrene, synthetic fibers such as polyester, polyamide and polyvinyl alcohol,
Organic materials such as woven or non-woven fabrics made of natural fibers, semi-synthetic fibers and the like, inorganic materials such as glass, quartz, ceramics and silica, and inorganic materials such as aluminum and stainless steel can be used. The present invention is particularly effective when the substrate is made of an organic material (organic substance).

[0007] The type of the undercoating film is not particularly limited as long as it can be interposed between the base material and the photocatalytic film and does not deteriorate the base material and does not impair the catalytic activity of the photocatalytic film. Without limitation, for example, Ti, Al, Co, C
r, Cu, Fe, Au, Ag, Pt, Pd, In, M
g, Sn, Zn and other metal thin films, SiO, SiO ₂ , Be
Metal oxide thin films such as O, MgO, Al ₂ O ₃ , SnO ₂ , and ZrO ₂ can be mentioned. In view of the object of the present invention, in the case of metal thin films, Ag, N
i, Cu, Au, Ti, Al, Pt, Pd and the like are preferably used, and in the case of a metal oxide thin film, SiO, SiO ₂ , Al ₂ O ₃ , SnO _{2 and the} like having no photocatalytic activity are preferably used. Is done. Although the thickness of the underlayer is not particularly limited, it is usually preferably in the range of several tens to several thousand degrees to achieve the object of the present invention. The base film may be formed on the above-mentioned base material by a known wet plating, electroless plating, vacuum deposition method, ion plating method, CVD method, sol-gel method or the like, but may be formed by a sputtering method described later. It is preferable to form a film because the heat resistance of the base material does not become a problem during the film formation, and the room for selection of the material of the base material is widened.

As the photocatalytic film, TiO ₂ , ZnO, W
A metal oxide film of O ₃ , Fe ₂ O ₃ , SrTiO ₃ or the like is used. Here, the thickness of the photocatalyst film is not particularly limited and can be variously selected depending on the use of the photocatalyst, etc., but in the case of the present invention, the catalytic activity of the photocatalyst film is favorably exhibited by the presence of the undercoat film. Several hundred to
In the case of a relatively thin photocatalytic film having a thickness of several thousand mm, it is particularly effective in improving the catalytic activity. The thickness ratio of the base film and the photocatalyst film is not particularly limited, but it is generally preferable that the base film / photocatalyst film is about 0.1 to 10. The photocatalyst film is made of a known binder fixing method, vacuum deposition method, ion plating method, CV
The film can be formed by a method such as a D method or a sol-gel method, but a sputtering method is preferably employed.

Hereinafter, a sputtering method suitably employed as a method for forming a base film and a photocatalytic film of the present invention will be described.

[0010] The sputtering method for forming a base film made of a metal thin film is to perform sputtering using a metal target in a vacuum or an inert gas. Is a metal that forms a desired metal thin film.

Further, a base film made of a metal oxide is formed.
Reactive sputtering involves the use of oxygen molecules.
Using a metal target in an inert gas containing
That perform sputtering while oxidizing these
However, as the metal target used here,
Metal oxide MeO of the desired metal oxide thin film _x
(Me represents a metal such as Si, Al, Mg, Be, Zr, etc.
X varies depending on the type of metal, but is preferably 0 to 10,
Or a positive number in the range of 0 to 5, and x is not necessarily
Si, A corresponding to (a does not need to correspond to a valence)
1, metals such as Mg, Be, and Zr.

In the case of a photocatalytic film, a metal target and
Then, the desired metal oxide MeO_x(Me is Fe,
W, SrTi , Ti, Zn, etc., and x represents the metal
Depending on the type, 0-10, preferably 0-5
Is a positive number in the range, where x necessarily corresponds to the valence of the metal
Is not required), especially photocatalysts
Excellent TiO_Two, ZnO, WO_Three, Fe_TwoO_Three, Sr
TiO_ThreeMetal, etc.
Get in an inert gas containing gas containing oxygen molecules
Sputtering while oxidizing, photocatalysis
A photocatalyst film made of a metal oxide film is formed.

Here, as the inert gas for sputtering, helium, argon, or the like is used, and particularly, argon which is industrially inexpensive is preferable. In the case of the reactive sputtering method, a metal is sputtered from the above-mentioned metal target in the presence of an inert gas containing a gas having an oxygen molecule (oxidizing gas), and a desired base material (in the case of a base film) or a desired base material is formed. The sputtered metal oxide film is formed on the ground film (in the case of a photocatalytic film). Examples of the oxidizing gas include oxygen, ozone, air, and water. Can be The flow ratio (volume ratio) between the inert gas and the oxidizing gas is appropriately selected,
Inert gas: oxidizing gas = 100: 0.1-100: 1
000 is preferable.

In the present invention, sputtering conditions such as a sputtering device, a reactive sputtering device, and a sputtering pressure are not particularly limited, and known devices and conditions can be employed. For example, an apparatus such as DC magnetron sputtering or facing sputtering can be used, and the pressure at the time of sputtering can be from high vacuum to atmospheric pressure.
It is performed under a vacuum of orr to 1 Torr.

In the photocatalyst of the present invention, a plastic film is used as a base material, the undercoat film is formed on the surface of the plastic film, and the photocatalyst film is further formed thereon.
The back surface of the plastic film may be subjected to adhesive processing. According to such a photocatalyst, for example, by attaching the photocatalyst to the surface of a reflector of a fluorescent lamp, the photocatalyst can be used so as to be replaceable with an existing fluorescent lamp.
In this case, the plastic film is not particularly limited, but in consideration of the above-described method of use, usually, a plastic such as polypropylene, polystyrene, polyethylene terephthalate, polycarbonate, or polyvinyl chloride has a thickness of about several tens to several hundreds μm. What was shape | molded in the film shape of this is used suitably. The means for the adhesive processing is not particularly limited as long as the plastic film can be attached to various objects such as indoor articles.

The photocatalyst of the present invention can be used in the same manner as a known photocatalyst. For example, by irradiating the surface of the photocatalyst with light, the photocatalyst film formed on the surface is excited to sterilize the photocatalyst. It exhibits an effect such as deodorization, and can be used for water purification, air purification, deodorization, oil decomposition, and the like. At this time, since the base film is interposed between the base material and the photocatalytic film, the base material can be used for a long time without deterioration even if the base material is made of, for example, an organic material. In addition, even when the base material is made of an amorphous material, the photocatalytic activity of the photocatalytic film can be sufficiently exhibited.

[0017]

The photocatalyst of the present invention can be used for a long time without deteriorating the base material, can exhibit the photocatalytic activity of the photocatalyst film well, and can be used when the photocatalyst film is thin. Even with this, high photocatalytic activity can be obtained.

[0018]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1, Comparative Example 1 4 × 5 (cm ² )
Polyester nonwoven fabric as a substrate, and this substrate is subjected to a facing sputtering method (target Ti),
5 ml / min of an argon gas is flowed into the sputtering apparatus as an inert gas, and a film is formed on the entire surface of the substrate for 5 minutes at a gas pressure of 5 mTorr and a target input power of 1.2 kW. After forming the base film, 5 ml / min of oxygen was used as an oxidizing gas and 5 ml / min of argon gas was applied by a facing sputtering method (target Ti).
With a gas pressure of 5 mTorr.
r, a film was formed on the entire surface of the base film formed on the surface of the base material at a target input power of 1.2 kW for 60 minutes, and 3000
Example 1 of forming a photocatalytic film composed of a TiO ₂ thin film of Å
Was obtained. On the other hand, a photocatalyst film of Comparative Example 1 was obtained by forming a photocatalyst film on the entire surface of the base material in the same manner as in Example 1 except that the base film was not interposed.

With respect to these photocatalysts, the breaking strength of the photocatalyst before and after exposure to a sunshine weather meter for 500 hours was measured, and the change in the breaking strength was examined. Table 1 shows the results.

[0021]

[Table 1] According to Table 1, it is recognized that the photocatalyst of the present invention prevents deterioration of the substrate due to light exposure.

Example 2, Comparative Example 2 A photocatalyst of Example 2 was obtained in the same manner as in Example 1, except that Pyrex glass of 4 × 5 (cm ² ) was used as the base material. Was. On the other hand, in Comparative Example 1, 4 ×
A photocatalyst of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that Pyrex glass of 5 (cm ² ) was used.

These photocatalysts were immersed in 22 ml of an amaranth (red pigment) solution (3 mg / liter),
Irradiation was performed with a 0 W ultra-high pressure mercury lamp (cut at 300 nm or less), and the change in concentration was measured with an ultraviolet-visible spectrophotometer to determine the decomposition rate of amaranth. Table 2 shows the results.

[0024]

[Table 2] According to Table 2, it is recognized that the photocatalyst of the present invention exhibits good photocatalytic activity.

Example 3, Comparative Example 3 4 × 5 (cm ² )
Polyester film is used as a substrate, and this substrate is subjected to a facing sputtering method (target Al).
Then, 5 ml / min of an argon gas was flowed into the sputtering apparatus as an inert gas, and a film was formed on the entire surface of the substrate at a gas pressure of 5 mTorr and a target input power of 1.0 kW for 1 minute. After forming a base film consisting of, counter facing sputtering method (target Ti)
Then, 5 ml / min of oxygen was used as an oxidizing gas and argon gas 5
flow into the sputtering device together with the gas pressure of 5 mT
orr, a target input power of 1.2 kW, a film was formed on the entire surface of the base film formed on the base material surface for 60 minutes, and 3
A photocatalyst film of a TiO ₂ thin film of 2,000 mm was formed to obtain a photocatalyst of Example 3. On the other hand, a photocatalyst film of Comparative Example 3 was obtained by forming a photocatalyst film on the entire surface of the base material in the same manner as in Example 3 except that the base film was not interposed.

These photocatalysts were immersed in 22 ml of an amaranth solution (3 mg / liter), irradiated with a 250 W ultra-high pressure mercury lamp (cut at 300 nm or less), and their concentration change was measured with an ultraviolet-visible spectrophotometer. The degradation rate of amaranth was determined. Note that the same measurement was performed for only the base material. Table 3 shows the results.

[0027]

[Table 3] According to Table 3, it is recognized that the photocatalyst of the present invention exhibits good photocatalytic activity.

Example 4, Comparative Example 4 4 × 5 (cm ² )
Is used as a substrate, and the substrate is subjected to a facing sputtering method (target Sn
O ₂ ), 5 ml / min of an argon gas as an inert gas is flowed into the sputtering apparatus, and a film is formed on the entire surface of the substrate for 5 minutes at a gas pressure of 5 mTorr and a target input power of 1.2 kW. After forming a base film composed of a SnO ₂ thin film, a facing sputtering method (target
At Ti), 5 ml / min of oxygen as an oxidizing gas was flown into the sputtering apparatus together with 5 ml / min of argon gas, and the entire surface of the base film formed on the surface of the base material at a gas pressure of 5 mTorr and a target input power of 1.2 kW was applied for 60 minutes. The photocatalyst of Example 4 was obtained by forming a film and forming a photocatalyst film composed of a 3000 ° TiO ₂ thin film. On the other hand, a photocatalyst film of Comparative Example 4 was obtained by forming a photocatalyst film on the entire surface of the base material in the same manner as in Example 4 except that no base film was interposed.

With respect to these photocatalysts, the breaking strength of the photocatalyst before and after exposure to a sunshine weather meter for 500 hours was measured, and the change in the breaking strength was examined. Table 4 shows the results.

[0030]

[Table 4] According to Table 4, it is recognized that the photocatalyst of the present invention prevents deterioration of the base material due to light exposure.

Example 5, Comparative Example 5 A photocatalyst of Example 5 was obtained in the same manner as in Example 4, except that Pyrex glass of 4 × 5 (cm ² ) was used as the base material. Was. On the other hand, in Comparative Example 4, 4 ×
A photocatalyst of Comparative Example 5 was obtained in the same manner as in Comparative Example 4, except that Pyrex glass of 5 (cm ² ) was used.

These photocatalysts were immersed in 22 ml of amaranth solution (3 mg / liter), irradiated with a 250 W ultra-high pressure mercury lamp (cut below 300 nm), and the change in concentration was measured with an ultraviolet-visible spectrophotometer. The degradation rate of amaranth was determined. Table 5 shows the results.

[0033]

[Table 5] According to Table 5, it is recognized that the photocatalyst of the present invention exhibits good photocatalytic activity.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of the present invention.

[Description of Signs] 1 Photocatalyst 2 Base material 3 Base film 4 Photocatalytic film

Claims (5)

[Claims] 1. A photocatalyst comprising a photocatalyst film formed on a base material with a base film interposed therebetween. 2. The photocatalyst according to claim 1, wherein the substrate is made of an organic material. 3. The photocatalyst according to claim 1, wherein the base film is a metal thin film or a metal oxide thin film. 4. The method according to claim 1, wherein the base film is a metal thin film obtained by performing sputtering using a metal target, or by performing reactive sputtering using a metal target in an inert gas containing a gas having oxygen molecules. The metal oxide thin film obtained, and the photocatalytic film is a metal oxide film obtained by performing reactive sputtering using a metal target in an inert gas containing a gas having oxygen molecules. 4. The photocatalyst according to 2, 3 or 4. 5. The substrate comprises a plastic film,
The photocatalyst according to claim 3 or 4, wherein a photocatalytic film is formed on a surface of the plastic film with a base film interposed therebetween, and an adhesive process is performed on a back surface of the plastic film.