JP2004358379A - Photocatalytic sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocatalytic sheet which has satisfactory porosity, excellent catalytic reactivity and transparency, can be manufactured at a low temperature and can be applied even to a plastic film or the like. <P>SOLUTION: This photocatalytic sheet has at least a metal oxide layer which is deposited on a substrate and has a grooved structure and a cracked shape. The groove width of the grooved structure of the metal oxide layer is made to be ≤1 μm and the area ratio occupied by the portion other than the grooved portion is made to be ≥75% and ≤90%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a photocatalyst sheet. Particularly, the present invention relates to a photocatalyst sheet having high catalytic properties.
[0002]
[Prior art]
Currently, NO _x and SO x in the _air, removing harmful substances or as formaldehyde, acetaldehyde, ammonia, volatile organic such as tetrachlorethylene and trichlorethylene a contaminant melted adsorption, decomposition, or water malodor, such as hydrogen sulfide Photocatalytic materials have attracted attention in various fields such as decomposing and removing chlorine compounds, and antibacterial and antifouling.
[0003]
As the photocatalyst, a powder or a thin film made of a metal oxide is known. Examples of such metal _{oxides, TiO 2, SrTiO 3, ZrO} 2, ZnO, ZnS, NbO 2, Nb 2 O 5, NiO, Ni-K 4 Nb 6 O 17, WO 3, WSe 2, SnO 2, Fe ₂ O ₃ , SiO, Cu ₂ O, KTaO ₃ , CdS, CdSe, CdTe, GaP, MoSe ₂ , and the like.
Among them, TiO ₂ (titanium oxide) is effectively used.
[0004]
In the case of a thin-film photocatalyst, a wet method such as a method of applying a solution containing a powder, a method of applying and heating a metal alkoxide solution, or a vapor phase method such as a vapor deposition method (see Patent Document 1) and a sputtering method are used. A film can be formed.
When using a wet method, a firing step is required. At this time, it is necessary to perform high-temperature treatment at about several hundred degrees Celsius to 1,000 and several hundred degrees Celsius although it varies depending on the substance used. Further, in the usual wet method, a binder is used, and the residual binder often causes coloring or the like even after firing.
Further, when the film is formed by a gas phase method, although the above-mentioned problem does not occur, the porosity is not sufficient, and when it is used as a photocatalyst, it is difficult to obtain a high catalytic reaction efficiency.
[0005]
[Patent Document 1]
JP-A-8-266910 [0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a photocatalyst sheet having sufficient porosity and having excellent catalytic reaction efficiency. Still another object is to provide a photocatalyst sheet which has transparency, can be manufactured at a low temperature, and can be applied to a plastic film and the like.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is a photocatalyst sheet comprising a grooved structure and a crack-shaped metal oxide layer provided at least on a substrate.
[0008]
The invention according to claim 2 is the photocatalyst sheet according to claim 1, wherein a groove width in the groove structure of the metal oxide layer is 1 μm or less.
[0009]
A third aspect of the present invention is the photocatalyst sheet according to the first or second aspect, wherein a straight continuous portion of the metal oxide layer that is not separated by the groove is 5 μm or less.
[0010]
According to a fourth aspect of the present invention, the ratio occupied by the portion other than the groove of the metal oxide layer is 75% or more and 90% or less in area ratio. It is a photocatalyst sheet.
[0011]
The invention according to claim 5 is the photocatalyst sheet according to any one of claims 1 to 4, wherein a protective layer is formed between the base material and the metal oxide layer.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
3 and 4 show an example of a layer configuration diagram of the photocatalyst in the present invention.
[0013]
In the present invention, a photocatalyst can be obtained by providing a metal oxide layer on a substrate.
As the substrate 1 that can be used in the present invention, a known material can be used. For example, a plastic film such as polymethyl methacrylate, polycarbonate, polystyrene, polyethylene sulfide, polyether sulfone, polyolefin, polyethylene terephthalate, polyethylene naphthalate, triacetyl cellulose, polyimide, or various substrates such as glass, wood board, and stone board can be used. it can. Further, it is preferable that the material be transparent, since the decorative property of the other sheet or the molded product is not impaired when the photocatalyst sheet of the present invention is applied to another sheet or a molded product. Further, a plastic film is preferable because it has flexibility and a wide range of application.
[0014]
Such a substrate may be one whose surface has been modified by corona treatment, plasma treatment, chemical treatment, coating treatment with wax or resin, or the like, if necessary.
[0015]
As the protective layer 2 in the present invention, silicon oxide or aluminum oxide can be used. In addition, iron, cobalt, zirconium, or other metal oxides, metal oxynitrides, metal nitrides, metal Fluoride or the like can be used. In addition, a high molecular compound such as a silicone resin or a fluorine-containing organic compound can be used, but it needs to be able to withstand the photocatalytic action of the metal oxide layer.
[0016]
As a method for forming the protective layer 2, a wet film forming process of applying a hydrolyzed metal alkoxide, metal chloride, or the like by microgravure coating, dip coating, screen coating, or the like, a vacuum evaporation method, a sputtering method, an ion Although a dry film forming process such as a plating method and a plasma CVD method can be used, any film forming method may be used. It is desirable that the film thickness of such an inorganic compound layer is in the range of several nm to 500 nm. However, if it is 5 nm or less, it may not be a continuous film due to an island shape. The thickness is more preferably 5 nm to 300 nm because cracks may occur in the film.
[0017]
As the metal oxide layer 3 in the present invention, a metal oxide exhibiting the properties of an n-type or p-type semiconductor can be used. Specific examples include oxides of zinc, niobium, tin, titanium, vanadium, indium, tungsten, tantalum, zirconium, molybdenum, manganese, iron, copper, nickel, iridium, rhodium, chromium, and ruthenium. Further, perovskites such as SrTiO ₃ , CaTiO ₃ , BaTiO ₃ , MgTiO ₃ , SrNb ₂ O ₆ , or composite oxides or oxide mixtures thereof can also be used.
Further, a metal such as platinum, palladium, chromium, ruthenium, or an oxide thereof may be supported on the metal oxide.
Further, the metal oxide layer itself may be porous.
[0018]
The metal oxide layer 3 of the present invention has a groove structure as shown in FIGS. 1 and 2, and is characterized in that it has a cracked shape. By adopting such a random groove structure, scattering characteristics of incident light are improved, which is preferable.
The groove width is not particularly limited, but is preferably 1 μm or less in consideration of optimization of the surface area, light transmittance and light scattering.
The thickness is not particularly limited, but is preferably 10 μm or less, more preferably 5 μm or less in consideration of optimization of light transmittance and the like.
Although the specific surface area is not particularly limited, it is preferably 50 m ² / g or more, and more preferably 100 m ² / g or more in consideration of optimization of catalytic reaction efficiency, light scattering property and the like.
[0019]
The metal oxide layer 3 of the present invention has a groove structure and is characterized by a crack-like shape. Specifically, as shown in FIG. Separated by five. In the present invention, it is preferable that the straight continuous portion 4 of the metal oxide layer 3 that is not separated by the groove 5 is 5 μm or less. If it is larger than this, the peninsula or island-shaped portion separated by the groove of the metal oxide layer becomes large, and the specific surface area deviates from the aforementioned optimum range.
Further, the proportion of the metal oxide layer occupied by peninsulas or islands other than the grooves is 90% or less, more preferably 85% or less, and preferably 75% or more in terms of area ratio. The area ratio at this time is an area ratio when the metal oxide layer is viewed from directly above.
[0020]
Further, the groove may be formed obliquely with respect to a normal line of the metal oxide layer 3. The depth of the groove is not particularly limited, and may be constant or not.
[0021]
The metal oxide layer 3 can be formed by a known film forming technique. For example, for forming a metal oxide film, a metal, a metal oxide, a metal suboxide, or the like corresponding to the metal oxide to be formed is used as a deposition source, and an evaporation method using heating with an electron beam or a plasma gun, or oxygen. A reactive evaporation method in which evaporation is performed while introducing a gas can be used.
[0022]
In addition, in order to form a metal oxide layer having a groove structure and a crack shape, the film formation pressure varies depending on the type of an evaporation source to be used, but the pressure is preferably in a range of 1 × 10 ⁻² Pa to 1 Pa. Is preferred. At the time of film formation, assist may be performed by plasma using an arbitrary gas, an ion gun, a radical gun, or the like. Depending on the target metal oxide, a vacuum deposition method such as sputtering, ion plating, or CVD may be used.
[0023]
Further, it is preferable to perform evaporation in an oblique direction. Specifically, the base material can be disposed obliquely with respect to the evaporation source to form a film.
Preferably, the angle between the normal of the base material and the direction in which the deposition material adheres is 45 ° or more, and more preferably 60 ° or more (FIG. 5).
[0024]
Further, in the present invention, when a plastic film is used as the base material, the film can be formed by a roll-to-roll method. Thereby, high productivity can be obtained.
[0025]
The metal oxide layer 3 obtained as described above can be surface-treated by any method such as a plasma treatment, a corona treatment, a UV treatment, and a chemical treatment. Further, post-processing can also be performed using any means such as baking by heat, pressure processing using a compressor, and laser annealing.
[0026]
The photocatalyst sheet obtained by the present invention can decompose bacteria, odorous substances, and harmful substances by mainly irradiating ultraviolet light to perform antibacterial, antifouling, deodorant, and purification. In addition, characteristics such as a change in surface wettability due to light irradiation can also be used. Furthermore, it can also be used for generating hydrogen and oxygen by utilizing photolysis of water.
[0027]
The photocatalyst sheet of the present invention can be applied to various uses. For example, the present invention may be applied to building materials such as an outer wall and an inner wall, a ceiling, a floor material, a door material, and a window material of a building, a window material of a car, and water purification.
[0028]
【Example】
Hereinafter, the photocatalyst sheet of the present invention will be specifically described.
[0029]
<Example 1>
The photocatalyst sheet 10 having the layer configuration of FIG. 3 was produced as follows. First, glass having a thickness of 0.5 mm was used as the substrate 1, and titanium oxide was formed thereon as the metal oxide layer 3. Titanium oxide was formed to have a thickness of 300 nm by a reactive vacuum evaporation method in which oxygen gas was introduced to evaporate titanium oxide. The film forming pressure at this time was 1 × 10 ⁻¹ Pa. Further, baking was performed at 450 ° C. for 30 minutes in the air. When the obtained polycrystalline titanium oxide was subjected to X-ray diffraction, it was found to be an anatase-type polycrystalline. The specific surface area measured by the BET multipoint method was 46 m ² / g.
[0030]
The photocatalytic performance of the photocatalyst sheet 10 obtained as described above was evaluated. A 50 mm × 50 mm piece of the photocatalyst sheet 10 was cut out and placed in a Pyrex (registered trademark) glass container having a volume of 1 L. 100 ppm of a mixture of acetaldehyde and air was added to the container. When the photocatalyst sheet was irradiated with black light at 5 mW / cm ² for 30 minutes, the acetaldehyde concentration inside the container was about 10 ppm.
[0031]
<Example 2>
The photocatalyst sheet 20 having the layer configuration shown in FIG. 4 was produced as follows. First, PEN having a thickness of 100 μm was used as the substrate 1, and aluminum oxide was formed thereon as the protective layer 2 to a thickness of 40 nm by a reactive vacuum deposition method in which oxygen gas was introduced to evaporate aluminum. . Subsequently, titanium oxide was formed as the metal oxide layer 3. Titanium oxide was formed to a thickness of 300 nm using an ion beam assisted vacuum evaporation method in which titanium oxide was evaporated while introducing an oxygen gas, and an oxygen ion beam was applied. The film forming pressure at this time was 1 × 10 ⁻¹ Pa. When the obtained polycrystalline titanium oxide was subjected to X-ray diffraction, it was found to be an anatase-type polycrystalline. The specific surface area measured by the BET multipoint method was 64 m ² / g.
[0032]
The photocatalytic performance of the photocatalyst sheet 20 obtained as described above was evaluated. A 50 mm × 50 mm piece of the photocatalyst sheet 20 was cut out and placed in a Pyrex (registered trademark) glass container having a volume of 1 L. 100 ppm of a mixture of acetaldehyde and air was added to the container. When the photocatalyst sheet was irradiated with black light at 5 mW / cm ² for 30 minutes, the acetaldehyde concentration inside the container was about 10 ppm.
[0033]
【The invention's effect】
According to the present invention, a photocatalyst sheet having sufficient porosity and having high catalytic efficiency can be obtained. Further, since it can be formed on a transparent or flexible substrate such as a plastic film, the applicable range is wide.
[0034]
[Brief description of the drawings]
FIG. 1 is an image diagram showing an example of an SEM image of a metal oxide layer surface according to the present invention.
FIG. 2 is a schematic view showing an example of a metal oxide layer surface according to the present invention.
FIG. 3 is a layer configuration diagram illustrating an example of a photocatalyst sheet according to the present invention.
FIG. 4 is a layer configuration diagram showing an example of a photocatalyst sheet in the present invention.
FIG. 5 is a schematic view illustrating a method for forming a metal oxide layer according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Protective layer 3 Metal oxide layer 4 Straight continuous part not separated by groove of metal oxide layer 5 Groove 6 Peninsular or island-shaped metal oxide layer 7 Incident angle 8 Deposition material 10 Photocatalytic sheet

Claims (5)

A photocatalyst sheet characterized by comprising a metal oxide layer having a groove structure and a crack shape on at least a substrate. The photocatalyst sheet according to claim 1, wherein a groove width in the groove structure of the metal oxide layer is 1 µm or less. 3. The photocatalyst sheet according to claim 1, wherein a straight continuous portion of the metal oxide layer that is not separated by a groove is 5 μm or less. 4. The photocatalyst sheet according to any one of claims 1 to 3, wherein a ratio occupied by a portion other than the groove of the metal oxide layer is 75% or more and 90% or less in area ratio. The photocatalyst sheet according to any one of claims 1 to 4, wherein a protective layer is formed between the substrate and the metal oxide layer.

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