JP3759960B2 - Photocatalyst carrier - Google Patents

Description

光触媒活性は、高い方から試料Ａ＞試料Ｃ＞試料Ｂの順序であることがわかる。フッ素含有アルカリ遮断膜アンダーコートに使用により、ソーダライムガラスを基板として使用しても、優れた光触媒活性を示す結果が得られている。
以上説明したように、本発明により製造した酸化チタン薄膜／フッ素含有アルカリ遮断膜／ガラス基板からなる構成の光触媒は優れた高活性を示す。また、この光触媒は、優れた光透過率を有することから、病院，オフィス，自動車内の空気浄化，さらには抗菌，防汚性能，防曇性能を目的とした窓ガラスに好適に使用することができる。
産業上の利用可能性
本発明により製造された光触媒担持体は、家庭，事務所，病院，あるいは半導体工業，液晶産業，薬品工業，食品工業，農林産業，医薬，精密機械工業等の各種産業におけるクリーンルーム，無菌室等における密閉空間、例えば安全キャビネット，クリーンボックス，貴重品の保管庫，貴重品の密閉搬送空間，クリーンな密閉空間（各種気体の存在下あるいは真空中）の清浄、室内空間の空気浄化、抗菌、防汚、透明板の防曇（親水性維持）等に用いることができる。
また、本発明になる光透過性含アルカリガラス繊維を基材とする光触媒担持体は、極めて優れた希薄有害有機ガスの分解能力を有していることが明かであり、半導体用超クリーン密閉空間や密閉搬送空間、各種用途のクリーンルーム、オフィスビルおよび一般住宅内の壁材やエアフィルターとして好適に使用することが可能である。Technical field
The present invention is particularly applicable to window glass and wall materials installed in hospitals, offices and automobiles, and can provide various performances such as air purification, antibacterial, antifouling, and antifogging in indoor spaces. Highly active that exhibits excellent functions for air purification in indoor spaces by using it as an ultra-clean sealed space for semiconductors, a sealed transfer space, clean rooms for various uses, wall materials in office buildings and ordinary houses, and air filters. The present invention relates to a photocatalyst carrier.
Background
Antibacterial oxide semiconductors such as titanium oxide, zinc oxide, tungsten oxide, iron oxide, etc., which have high photocatalytic activity and excellent durability, can be used as various photoreaction reactors immobilized on solid supports. Proposed. For example, Japanese Patent Application Laid-Open No. 63-97234 discloses an immobilized photocatalyst in which the surface of transparent material particles, flakes or fibers is coated with a thin film of titanium oxide to which platinum, palladium or the like is added.
However, by developing an article carrying a photocatalyst having higher photoreaction efficiency, it can be used not only as an antibacterial agent but also as an environmental pollution prevention material. It is sent.
Among various photocatalytic materials, titanium oxide having the highest photocatalytic activity and excellent durability has already been put into practical use as an antibacterial agent in the form of fine particles. However, titanium oxide can be excited only by ultraviolet light, and the amount of light that can be used under actual use conditions is very small. Therefore, when a photocatalyst is used indoors, it can be said that it is most suitable to apply to a window glass in that both illumination and sunlight can be used.
However, when it is applied to a window glass, it is important that the film has high transparency. Therefore, a material based on fine particles of titanium oxide cannot be used. Therefore, if a highly active-highly transparent photocatalytic thin film can be obtained, its performance will be maximized and the use will be dramatically increased.
In addition, another major problem when the photocatalytic thin film is applied to a window glass is that its activity is greatly reduced by diffusion of Na ions from the soda-lime glass substrate. As a countermeasure, it has been studied to apply a silica undercoat for preventing Na diffusion on glass (Paz et al., J. Mater. Res., Vol. 10, p. 2842, 1995). There is also a report that this method can provide photocatalytic activity close to that of a titanium oxide thin film coated on a quartz substrate.
Furthermore, in recent years, in the semiconductor field, with the increase in the density of elements, there is a problem of yield reduction due to adsorption of a gas composed of a small amount of organic substance in a clean room to the element substrate. In general houses, allergies caused by various plasticizers such as formaldehyde and acetaldehyde generated from building materials present in a small amount in the room are becoming serious.
Since the photocatalyst such as titanium oxide has a strong oxidizing power against organic matter, it can decompose various organic matter gases present in the room, so as to solve the problem of lowering the yield of the semiconductor or the allergy problem. It has the potential to become a key material.
However, when decomposing organic gas using a photocatalyst, its concentration is very low, so it is important to improve the essential activity of the photocatalyst and simultaneously increase its surface area. .
Conventionally, for the purpose of decomposing a dilute organic gas, attempts have been made to carry a photocatalyst on a shoji paper or a glass fiber cloth support (for example, JP-A-1-139139). . However, although shoji paper has the advantage of a large surface area, it is organic in itself, so deterioration is unavoidable for a long time, and it can lead to new sources of contamination, so its use is limited to a narrow range . In addition, when a photocatalyst is directly supported on a glass fiber cloth, high photocatalytic activity cannot be obtained. The reason is that the alkali component diffused from the glass in the process of fixing the photocatalyst to the glass fiber reduces the crystallinity of the photocatalyst.
Accordingly, an object of the present invention is to provide a photocatalyst carrier having a photoreaction efficiency higher than that of conventional photocatalysts and excellent durability.
In addition, the problem of the present invention is to solve the above-mentioned problems of the prior art and maintain high photocatalytic activity even when a base material having an alkali-containing glass composition is used. And providing a photocatalyst carrier excellent in antifogging performance.
Also, the object of the present invention is to solve the above-mentioned problems of the prior art and to provide a semiconductor ultra-clean sealed space and sealed transfer space, clean rooms for various uses, office buildings, air purification in automobile interiors, and wall materials in ordinary houses By providing a photocatalyst carrier that can be used as a window material or an air filter to efficiently decompose and remove harmful organic gases, and has high antibacterial performance, antifouling performance, and antifogging performance. is there.
Disclosure of the invention
The present inventors have found that when fluorine is contained in a photocatalytic layer made of an oxide semiconductor such as titanium oxide, the photocatalytic activity of the oxide is increased.
The material of the photocatalyst of the present invention is titanium oxide (TiO₂) Can be used. Titanium oxide has high activity and excellent physicochemical stability and is currently most widely used. For example, a titanium oxide crystal thin film can be formed by using a vacuum evaporation method.
The photocatalytic activity of the photocatalyst of the present invention strongly depends on the film thickness or the minimum dimension (for example, the fibrous photocatalyst should be referred to as the minimum dimension instead of the film thickness, but the film thickness will be described below). If the film thickness is too thin, light cannot be absorbed sufficiently, and if it is too thick or too large, the photocarriers generated in the film cannot diffuse to the outer surface of the film, so that the catalytic activity decreases. Although the optimum film thickness varies depending on the use conditions, in the case of a titanium oxide photocatalyst thin film, the film thickness is 5 nm to 2 μm, more preferably 20 nm to 1 μm, and even more preferably 50 to 200 nm. The activity can be expressed.
In the photocatalyst of the present invention, the photocatalyst itself may have a film shape, flake shape, granular powder shape, or fiber shape.
The photocatalyst of the present invention can be produced by a vacuum vapor deposition method, a chemical vapor deposition (CVD) method, a liquid phase deposition method, a sol-gel method, a fine particle baking method, or other production methods, particularly acetylacetone. A thin film of a photocatalyst can be easily prepared by using a sol-gel method using a complex in which titanium alkoxide is chemically modified with a chelating agent as a raw material and controlling the firing conditions.
Moreover, it can coat | cover and use on the surface of various base materials, However, As this base material, the thing of plate shape, film shape, flake shape, particle shape, rod shape, fiber shape, and other shapes can be used.
When not covered with such a base material, it is preferable to make the whole surface of a photocatalyst work as a reaction surface.
In the present invention, when the photocatalytic thin film is formed on the substrate surface,Material, GalaOrIt is possible to use plates, films, flakes, particles, powders, rods, fibers, and other shapes. When a glass plate substrate is used as a window glass, it is preferable to transmit light that can excite the photocatalytic film, that is, ultraviolet light and / or visible light, and 20% per 1 cm of the material of the substrate. As described above, the light transmittance is preferably 50% or more, and more preferably 90% or more.
If the glass base material does not transmit light, the excitation light does not pass through the inside of the base material and reach the photocatalyst film such as titanium oxide on the back side, so the utilization efficiency of sunlight is reduced. .
The surface of the base material may be smooth. However, when transparency such as a window glass is not required, the surface becomes rough to improve the photocatalytic reaction rate. Preferably it is. The surface roughening method is not particularly limited, and chemical etching using an HF aqueous solution and physical abrasion using an abrasive may be used. The depth of the unevenness is preferably about 200 nm or more in order to scatter ultraviolet light and / or visible light. However, if the depth of the unevenness is too large, the mechanical strength of the base material becomes small and is easily damaged. As a result, the upper limit is preferably 0.1 mm, and particularly preferably in the range of 0.5 to 10 μm. is there. The pitch of the unevenness is not particularly limited, but naturally varies depending on the depth of the unevenness. Usually, about 10 times the depth of the unevenness is used.
The feature of the present invention is that the photocatalytic activity is remarkably improved by containing fluorine in the photocatalytic layer. If the fluorine doping amount is too small, the effect of improving the photocatalytic activity is small. Therefore, it is preferable to contain 0.02 to 1.0% by weight of fluorine in the photocatalytic layer. As a method for containing fluorine in the photocatalyst layer, a fluorine compound may be added directly to the material for forming the photocatalyst layer, and a fluorine-containing layer is previously provided between the various substrates and the photocatalyst layer. The fluorine may be diffused and transferred from the fluorine-containing layer to the photocatalyst layer during firing of the photocatalyst layer.
For example, by adding a fluorine compound, for example, trifluoroacetic acid (TFA), to a solution of titanium alkoxide, which is a sol-gel raw material, fluorine remains in the film after baking, thereby increasing the photocatalytic activity. Can do.
The fluorine compound is preferably added to a solution containing a complex of titanium alkoxide and a chelating agent, so that the photocatalytic activity can be remarkably increased as compared with the case where no chelating agent is present. The concentration of titanium alkoxide and the concentration of acetylacetone in the case of adding acetylacetone are the same as those described above, and the TFA addition amount may be 0.01 or more in terms of molar ratio with respect to Ti. A range of 1 is desirable. The F / Ti atomic ratio is close to zero on the surface of the titanium oxide thin film after firing, but the F / Ti atomic ratio is 0.05 to 0.1 inside the thin film.
When using a base material having an alkali-containing glass composition, such as glass fiber and glass plate, as the base material for the photocatalyst of the present invention, a silicon oxide layer or other metal oxide layer containing fluorine as the fluorine-containing layer. By this, this layer also acts as an alkali blocking layer, and it is possible to prevent alkali metal ions such as Na ions in the glass fiber from diffusing and moving into the photocatalyst layer to impair the photocatalytic activity of the photocatalyst layer. it can.
In the present invention, fluorine compounds other than TFA include HF, NH_FourF, Freon, or the like can be used.
In the present invention, when the photocatalytic layer is coated on the substrate surfaceAlkaline glassIt is one of the features of the present invention that a fluorine-containing layer is provided in advance between the substrate surface and the photocatalyst layer. In that case, fluorine diffuses into the thin film of the photocatalyst layer from the fluorine-containing layer which is an undercoat layer by heating the photocatalyst layer such as titanium oxide at a heat treatment, preferably 450 to 550 ° C. for 10 minutes to 2 hours. As a result, the photocatalytic activity is improved. In addition, when a chemical vapor deposition (CVD) method or a sol-gel method is used, a heat treatment is required for crystallizing the initially formed photocatalyst layer thin film such as amorphous titanium oxide. And this crystallization heat processing are normally performed at 450-550 degreeC for 10 minutes-2 hours. When a fluorine-containing layer that is an undercoat layer is provided, the fluorine diffusion from the fluorine-containing layer naturally occurs during the crystallization heat treatment. Therefore, in this case, it is not necessary to perform a special treatment for fluorine diffusion.
Although it does not specifically limit as a fluorine-containing layer, The fluorine-containing silica membrane obtained at low cost can be used conveniently. Further, the production of the fluorine-containing silica film is not particularly limited, but a liquid phase film forming method using a precipitation reaction from a hydrofluoric acid solution in which silica exists in a supersaturated state is preferable. In particular,Alkali-containing glassWhen using a fabric substrate made of fiber, configure the substrate.Alkali-containing glassIn order to completely cover each fiber, the liquid phase film forming method using the silica supersaturated hydrofluoric acid solution is most preferable.
In the present invention, when an undercoat composed of a fluorine-containing layer is provided, the fluorine contained in the undercoat diffuses into the titanium oxide film, and the film quality of titanium oxide is improved. And the base material contains an alkali metal componentBecauseIn addition to improving the photocatalytic film quality such as titanium oxide, the fluorine-containing layer functions as an alkali blocking film that prevents the diffusion of alkali metal ions such as Na ions in the glass substrate.
Although the kind of fluorine-containing layer in the present invention is not limited, an oxide thin film such as a silica thin film, a zirconia thin film, or an alumina thin film can be suitably used from the viewpoint of preventing the diffusion of Na ions and other alkali metal ions. .
The method of incorporating fluorine into the fluorine-containing layer, that is, the fluorine doping method differs depending on the method for producing the fluorine-containing layer. In particular, as described above, by immersing the substrate in an aqueous solution of hydrosilicofluoric acid containing silicon dioxide (silica) in supersaturation, and depositing and growing a silicon dioxide film on the substrate surface (liquid phase deposition method) The produced silica thin film not only can be formed at a low temperature, but also fluorine is naturally taken into the silica thin film, so that it can be suitably used particularly for the purpose of the present invention.
From the infrared absorption spectrum, it is clear that fluorine is doped mainly in the form of Si-F bonds in the silica thin film. The fluorine doping amount in the fluorine-containing layer varies depending on the type of fluorine-containing layer and the production method, but in order to improve the photocatalytic activity, a range of 0.1 to 20 atomic%, particularly 2 to 10 atomic% is appropriate. is there. If the fluorine doping amount is less than 0.1 atomic%, the fluorine diffusion from the fluorine-containing layer (alkali blocking film) to the photocatalytic thin film such as titanium oxide becomes insufficient. Conversely, if the fluorine doping amount exceeds 20 atomic%, the alkali blocking performance also decreases. To do. The film thickness of the fluorine-containing layer may be set to an appropriate range in consideration of the diffusion prevention performance of Na ions and other alkali metal ions possessed by the material. When the fluorine-containing layer is composed of a silica film, a film thickness of 30 nm or more is suitable, and from 30 to 100 nm is particularly suitable from the viewpoint of cost-performance.
As other methods for producing the fluorine-containing layer, known methods such as a vacuum deposition method, a sputtering method, a chemical vapor deposition (CVD) method, a sol-gel method, and a baking method by spraying fine particles can be used.
When a fluorine-containing layer is produced by a method (liquid phase deposition method) in which a substrate is immersed in an aqueous solution of hydrofluoric acid containing supersaturated silicon dioxide to deposit and grow a silicon dioxide film on the substrate surface, As a means for producing a supersaturated state of silicon, a method of adding an aqueous solution of boric acid to a saturated solution of hydrofluoric acid silicon dioxide (Japanese Patent Publication No. 63-65620), A method of adding a substance such as aluminum to a saturated solution (Japanese Patent Laid-Open No. 62-20876), a method of adding water to a saturated solution of silicon hydrofluoric acid (Japanese Patent Laid-Open No. 3-237002) And by using the temperature dependence of the solubility of silicon dioxide in hydrofluoric acid, specifically, by increasing the concentration of hydrofluoric acid in a substantially saturated solution of silicon dioxide, the supersaturation of silicon dioxide Make a solution The method or the like is known to be (JP 61-281047 and JP Hei 3-112806), but may be used any of these methods in the present invention.
The above isAlkaline contentGlass baseMaterialAlthough the case where a fluorine-containing layer is previously provided between the surface and the photocatalyst layer has been described, instead of providing such a fluorine-containing layer, in the compound solution for forming a metal oxide for photocatalyst to be brought into contact with the surface of the substrate A fluorine compound such as trifluoroacetic acid may be contained. That is, for example, in the case of the sol-gel method, the substrate surface is coated with a compound solution containing a complex of titanium alkoxide and a chelating agent, and trifluoroacetic acid, and contains fluorine by heating in an oxidizing atmosphere. A metal oxide photocatalyst film is obtained.
The mechanism of action of the oxide-based semiconductor photocatalyst such as titanium oxide is explained as follows. When the photocatalyst is irradiated with light, photocarriers (excited electron-hole pairs) generated by excitation of electrons in the valence band of the semiconductor that has absorbed the light to the conduction band are generated from the inside of the photocatalyst to the surface. And react with adsorbed oxygen or oxide hydroxyl groups present in the surface layer of the photocatalyst. This reaction results in O^2-And active oxygen such as OH is generated. These active oxygens oxidize and decompose organic substances adsorbed on the surface of the photocatalyst.
According to the present invention, the photocatalytic activity is improved by fluorine doping into the photocatalytic film. It is not clear at present why the photocatalytic activity performance is improved by doping fluorine into the photocatalytic film. However, by doping fluorine in the thin film of the photocatalyst layer such as titanium oxide, the thin film of the photocatalyst layer such as titanium oxide that was originally high in light transmittance is colored gray and has low light transmittance. In particular, it is presumed that the light absorption efficiency of the photocatalyst layer of titanium oxide or the like increases, so that the light use efficiency is increased.
In the case of providing a fluorine-containing layer, andAlkali-containing glassWhen a glass fiber substrate or glass plate substrate having an alkali metal component as the substrate is used, for example, a glass fiber substrate or glass plate substrate having a soda-lime silicate glass composition, a fluorine-containing layer In addition to the above-described improvement in photocatalytic activity, the performance deterioration of the titanium oxide thin film can be suppressed by preventing Na from diffusing from the substrate. That is, in a conventional photocatalyst using an alkali-containing glass substrate, if Na ions in the substrate enter the titanium oxide film during the production process, the crystallinity of the film is inhibited, or the Na ions are excited electrons-positive. Since it acts as a recombination center of the hole pair, it is considered that the performance is deteriorated because the diffusion of the photocarrier to the photocatalyst surface is inhibited and the charge separation efficiency is lowered. According to the present invention, even when an alkali-containing glass substrate is used, the alkali-blocking film (fluorine-containing layer) prevents alkali metal ions in the substrate from entering the titanium oxide film, and the crystallinity of the film It is concluded that, since there is no alkali metal ion that acts as a recombination center of excited electron-hole pairs, a decrease in charge separation efficiency is prevented, thereby preventing deterioration of photocatalytic activity.
Air filters for clean rooms and air purifiers areAlkali-containing glassThis is one of the most important applications of a photocatalyst carrier obtained by coating a fiber base material with a photocatalyst layer. Air filter should not clog the meshThe aboveIt is necessary to form a photocatalytic thin film on each fiber.SaidThe fiber cloth may have a mesh size selected according to the intended use. For example, it has an average diameter of 0.20 to 5 μm.SaidIt is made of fiber and has a thickness of 0.1 to 2 mm, and 3 to 50 mmH when the passing wind speed is 320 cm / min.₂Ventilation resistance expressed by pressure loss of OSaidFiberClothPreferably used.Alkali-containing glassAs the material of the fiber, soda lime silicate glassSusA material that can use fibers and can pass light, particularly ultraviolet light, is preferable..
As a base materialGlassSince the fibrous material has a large surface area, the activity of the photocatalyst coated on the surface is improved as compared with a glass plate substrate or the like.
For example, an example of forming a photocatalytic layer on a substrate by sol-gel method using titanium oxide as an example will be described. It has been found that when the added solution is applied on a substrate and baked, fluorine remains in the baked film and the photocatalytic activity can be increased. In addition, an increase in electrical conductivity due to fluorine doping may contribute to the improvement of the photocatalytic activity.
Examples of the titanium alkoxide used in the present invention include compounds represented by the following general formula (1).
Ti- (OR)_Four  (1)
(Here, R represents a hydrogen atom and an organic group having 1 to 5 carbon atoms.)
Specific examples of the titanium alkoxide include tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, tetraisopropoxytitanium isopropanol complex, tetra n-propoxytitanium, tetraisobutoxytitanium, tetra n-butoxytitanium, tetra sec- Butoxytitanium, tetra-t-butoxytitanium, etc. can be used conveniently. In addition, tetra (2-ethylhexyloxy) titanium, tetrastearyloxytitanium, di-n-butoxy-bis (triethanolaminato) titanium, titanium isopropoxyoctylene glycolate, titanium stearate, etc. may be used. Good.
A titanium halide alkoxide such as titanium monochloride trialkoxide or titanium dichloride dialkoxide in which a part of the alkoxy group (—OR) of the compound represented by the general formula (1) is replaced with a halogen group can also be used. . Moreover, it is also possible to use alkoxytitanium organic acid salts in which at least one of the alkoxy groups of the titanium alkoxide is replaced with organic acids such as acetic acid, propionic acid, butanoic acid, acrylic acid, and methacrylic acid.
In the present invention, a noble metal such as platinum, gold, palladium, or silver can be supported on the surface of a photocatalyst such as titanium oxide, and the photocatalytic reaction rate can be further improved by supporting the noble metal. As a method for supporting a noble metal on the outer surface of the photocatalyst film, an impregnation method, a precipitation method, an ion exchange method, a photodeposition method, a kneading method, or the like can be used. Platinum can be most preferably used as the noble metal. The supported amount is preferably in the range of 0.01 to 20% by weight, more preferably in the range of 0.1 to 2.5% by weight, based on the weight of the titanium oxide thin film.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.
Example 1
[Soda lime glass substrate + fluorine-containing silica film + titanium oxide film not containing fluorine]
85.6 g (0.3 mol) of titanium tetraisopropoxide (Ti (OPr)_Four60.3 g (0.6 mol) of acetylacetone (AcAc) was gradually added dropwise to the mixture using a burette and stirred for about 1 hour to stabilize Ti (AcAc).₂(OPr)₂A complex solution was obtained (mother liquor). The mother liquor obtained (Ti (AcAc)₂(OPr)₂The complex solution was diluted 3.3 times with ethanol and then sufficiently stirred to obtain a uniform coating solution of a titanium compound.
Next, fluorine-containing SiO₂A soda-lime glass substrate with a film (substrate A) was prepared as follows. 50 ml of a 3.9 mol / liter hydrofluoric acid aqueous solution in which silicon dioxide is saturated and dissolved is kept at 35 ° C., and 50 ml of 35 ° C. water is added to supersaturate 1.95 mol / liter of silicon dioxide. An aqueous solution of hydrosilicofluoric acid was prepared. A soda lime glass substrate (Substrate B: dimension 20 × 50 × 1.0 mm) is immersed in a bath of this aqueous solution maintained at 35 ° C., maintained for about 2 hours, and then pulled out of the bath. A glass substrate (substrate A) covered with a fluorine-containing silicon dioxide film having a thickness of about 60 nm (film thickness 60 nm, fluorine content about 5 atomic%) was obtained.
The substrate A was immersed in a bath of the above titanium compound coating solution, and the substrate was lifted from the bath at a pulling rate of 3.2 cm / min to form a thin film on the substrate surface. After leaving it for about 30 minutes, it was baked at 500 ° C. for 30 minutes to form a titanium oxide thin film on the surface of the substrate A to obtain a photocatalyst. A photocatalyst sample obtained from the substrate A is designated as sample B.
Comparative Example 1
[Soda lime glass substrate + titanium oxide film not containing fluorine]
Untreated soda lime glass substrate as substrate B (composition: SiO₂/72.6%, Al₂O_Three/1.8%, Na₂O / 13.5, CaO / 8.9%, MgO / 3.9%, Fe₂O_Three/0.1%, 20 × 50 × 1.0 mm), and the substrate B is immersed in the titanium compound coating solution bath obtained in Example 1, and the pulling rate is 3.2 cm / min. The substrate was lifted from the bath to form a thin film on the substrate surface. After leaving it for about 30 minutes, it was baked at 500 ° C. for 30 minutes to form a titanium oxide thin film on the surface of the substrate B to obtain a photocatalyst. A photocatalyst sample obtained from the substrate B is designated as sample B.
Comparative Example 2
[Soda lime glass substrate + silica film + titanium oxide film not containing fluorine]
As the substrate C, the substrate B is made of SiO by a sol-gel method.₂A soda lime glass substrate (20 × 50 × 1.0 mm) with a film (thickness 100 nm) on both sides was prepared as follows. That is, to 50 g of ethyl silicate (“ethyl silicate 40” manufactured by Colcoat Co., Ltd.), a solution obtained by adding 6 g of 0.1N hydrochloric acid and 44 g of ethyl cellosolve and stirring for 2 hours at room temperature was placed on a soda lime glass substrate at 1000 rpm. The glass substrate with one surface covered with a silicon dioxide film was obtained by performing spin coating for 10 seconds at 720 and further baking at 720 ° C. for 120 seconds. The above operation was repeated on the other surface of the substrate C to coat each surface of the substrate C with a silicon dioxide film having a thickness of 100 nm.
The substrate C was immersed in the titanium compound coating solution bath obtained in Example 1 on the substrate C, and the substrate was lifted from the bath at a pulling rate of 3.2 cm / min to form a thin film on the substrate surface. . After leaving it to stand for about 30 minutes, it was baked at 500 ° C. for 30 minutes to form a titanium oxide thin film on the surface of each substrate C to obtain a photocatalyst. A photocatalyst sample obtained from the substrate C is designated as sample C.
As a result of the film thickness analysis of the titanium oxide thin film by a scanning electron microscope for these samples A to C (measurement accuracy = about 10%), the thickness of each sample A to C was about 100 nm. As a result of measurement by X-ray diffraction, all films were anatase type titanium oxide (TiO 2).₂) It became clear that it had a crystal structure.
The catalyst activity of the samples A to C obtained in Example 1 and Comparative Examples 1 and 2 was coated with TMCTS on the surfaces of the samples A to C, and irradiated with light so that the catalyst photolyzed TMCTS. It investigated by the method (Tada, Langmuir, 12th volume, No. 4, pp.966-971, 1996) to measure. The results are summarized in Table 1.
In the Tada method, the catalytic activity of the obtained photocatalyst sample is coated with 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) on the surface, and the catalyst is irradiated with light to photolyze TMCTS. This is a method for measuring speed (Tada, Langmuir, Vol. 12, No. 4, 966-971, 1996). The above sample is UV / O_ThreeAfter washing (50 ° C. for 10 minutes), it was set in a vacuum desiccator, and the pressure was reduced to about 10 Torr with a vacuum pump, and then the internal temperature was maintained at 80 ° C. After closing the system, 200 μL of 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) was injected with a syringe and heated for 30 minutes. Furthermore, while reducing the pressure with a vacuum pump, the temperature was raised to 100 ° C. and heated for 30 minutes to cold trap unreacted TMCTS. Thereby, a TMCTS monomolecular film was formed on various photocatalytic thin films. The sample having a hydrophilic surface changed to water repellency by the formation of the TMCTS monomolecular film. By irradiating light to the surface of the titanium oxide film of each sample plate at a distance of 20 cm using a 2 kW high pressure mercury lamp as a light source, the methyl group of the TMCTS monomolecular film is oxidized and decomposed, and the hydrophilicity of the surface gradually increases. Increased. The higher the oxidative decomposition rate of the TMCTS monomolecular film, the greater the photocatalytic activity of the sample.

Sample with higher photocatalytic activityA>It can be seen that the order of sample C> sample B is satisfied. Even when soda lime glass is used as a substrate, a result showing excellent photocatalytic activity is obtained by using the fluorine-containing alkali barrier film undercoat.
As described above, the photocatalyst having a structure comprising the titanium oxide thin film / fluorine-containing alkali barrier film / glass substrate produced according to the present invention exhibits excellent high activity. Moreover, since this photocatalyst has excellent light transmittance, it can be suitably used for window glass for purifying air in hospitals, offices and automobiles, and for antibacterial, antifouling and antifogging performances. it can.
Industrial applicability
The photocatalyst carrier produced according to the present invention is used in clean rooms, aseptic rooms, etc. in various industries such as homes, offices, hospitals, semiconductor industry, liquid crystal industry, pharmaceutical industry, food industry, agriculture and forestry industry, medicine, precision machinery industry, etc. Sealed space such as safety cabinets, clean boxes, storage of valuables, sealed transport space for valuables, clean sealed spaces (in the presence of various gases or in vacuum), air purification of indoor spaces, antibacterial, antifouling It can be used for anti-fogging (maintaining hydrophilicity) of a transparent plate.
Moreover, it becomes this inventionLight transmissive alkali-containing glassIt is clear that the photocatalyst carrier based on fiber has an extremely excellent ability to decompose dilute toxic organic gases. Ultra-clean sealed space and sealed transport space for semiconductors, clean rooms for various applications, office buildings And it can be suitably used as a wall material or an air filter in a general house.

Claims (9)

A photocatalyst carrier comprising a fluorine-containing film provided on the surface of a base material that is a light-transmitting alkali-containing glass substrate, and a photocatalyst film made of titanium oxide doped with fluorine on the fluorine-containing film. The substrate is plate-like, film-like, flake-like, particulate, powder, photocatalyst carrier according to claim 1 having a rod-like or fibrous shape. 3. The photocatalyst carrier according to claim 2, wherein the substrate is made of glass fibers having a soda lime silicate glass composition. The photocatalyst carrier according to any one of claims 1 to 3 , wherein fluorine in the photocatalyst film is diffused and moved from a fluorine-containing film provided between the substrate surface and the photocatalyst film. The photocatalyst carrier according to any one of claims 1 to 4 , wherein the fluorine-containing film has a barrier property against diffusion of an alkali component. Claims 1, wherein the alkali shut-off film is a fluorine-containing silica film was deposited by a predetermined time immersed in hydrosilicofluoric acid solution containing the substrate in a supersaturated silica according to any one of 5 Photocatalyst carrier. 6. The photocatalyst carrier according to claim 5, wherein the alkali blocking film has a thickness of 30 to 100 nm. 6. The photocatalyst carrier according to claim 5, wherein the alkali blocking film contains 0.1 to 20 atomic% of fluorine. 6. The photocatalyst carrier according to claim 5, wherein the fluorine-containing film comprises a film containing silica as a main component.