PHOTOCATALYTIC FUNCTIONAL MATERIAL AND METHOD OF PRODUCTION THEREOF

Abstract: A photocatalytic functional material having an excellent photocatalytic activity even by a low temperature heat treatment and having a high mechanical strength of the surface. The photocatalytic functional material of the present invention comprises a surface layer (a photocatalytic functional layer) containing a photocatalyst, an electron-trapping metal and a photodegradation-resistant matrix. Though the major proportion of the photocatalyst (TiO 2 particles, and the like) in the photocatalytic functional layer are covered with the photodegradation-resistant matrix (a thermosetting resin, and the like), the electron-trapping metal effectively traps the electrons generated by the photocatalytic reaction, retains positive holes and generates active oxygen species, so that the photocatalytic function such as deodorant and antimicrobial activities can be fully exhibited.

Description: Technical field to which the invention belongs The present invention relates to a photocatalytic functional material having many functions such as antimicrobial activity, preventing smell, stainresistance, or decomposition of harmful substances (NOx, and the like) based on the photocatalytic function. Particularly, it relates to a photocatalytic functional material which is prepared at low temperature (about 300°C or lower). Prior art As a method for adding a function of antimicrobial property, stainproof property and deodorizing property, and the like, to the surface of a substrate, a method of forming a thin film of a photocatalyst such as an anatase type titanium oxide, and the like, on the surface of a substrate has heretofore been proposed. As one of the methods, there is a method of kneading anatase type titanium oxide particles with a binder and coating the resulting material to the surface of a substrate and subjecting to heat treatment. As the other method, there is a method disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 253544/1993 filed by the present applicant. This method is a method for producing a plate-shaped member (tile, and the like) which is to constitute a wall surface, floor surface or a ceiling surface of a residential space. In this method, a binder layer is formed on the surface of the plate-shaped member, a photocatalyst fine powder mainly comprising an anatase type titanium oxide is so sprayed on the surface of the binder layer as to expose a part of the powder from the binder layer and adhered thereto, and then, after melting the binder layer by heating within the range of 300 °C or higher and less than 900 °C, the binder layer is solidified by cooling. EP 0 684 075 describes a multi-functional material which is divided into a type in which a photo-catalytic layer having a photo-catalytic function is directly disposed on the surface of a substrate (1) and another in which the photo-catalytic layer (2) is indirectly disposed on the surface of the substrate (1) through a binder layer (6). The mode of binding of photo-catalytic particles constituting the photo-catalytic layer (2) includes binding by surface energy and binding by solid phase sintering. The structure of the photo-catalytic layer (2) includes the structure in which fine particles are packed into gaps between the photo-catalytic particles and another in which they are not. Further, there is a structure in which metals such as Ag and Pt are fixed to the surfaces of the photo-catalytic particles and another in which they are not. EP 0 633 064 describes a photocatalyst composite which comprises a substrate having particles of a photocatalyst such as titanium oxide, adhered thereon via a less degradative adhesive such as a fluorinated polymer comprising a copolymer of a vinyl ester and/or vinyl ether and a fluoroolefin, or a silicon based polymer or cement. Furthermore, a process for producing the photocatalyst composite and a coating composition containing the photocatalyst composite are described. Problems to be solved by the invention In the above-mentioned method wherein anatase type titanium oxide particles are kneaded with a binder and the material is sprayed to the surface of a substrate, and subjected to heat treatment, almost all the active sites of the photocatalyst particles are covered by the binder so that characteristics of the photocatalyst function such as deodorizing property, and the like, are not sufficient. Also, according to the method of Japanese Laid-Open Patent Publication (Kokai) No. 253544/1993, deodorizing property, and the like, are good if the material is subjected to heat treatment at 300 °C or higher to less than 900 °C. However, by a low temperature heat treatment of less than 300 °C, additives in the binder cannot sufficiently be removed so that good deodorizing property, and the like, cannot be obtained. Accordingly, it was difficult to add good photocatalytic functions such as excellent deodorizing characteristics, and the like, to a substrate such as a plastic having poor heat resistance. Also, according to the method of Japanese Laid-Open Patent Publication (Kokai) No. 253544/1993, when the heat treatment temperature is less than 800 °C, the photocatalyst layer forming the surface of a substrate becomes porous with a porosity of 40% or more. Further, it has a structure in which the photocatalyst particles are exposed to the outermost surface so that there is a tendency that the surface is easily peeled off. The present invention has been accomplished in view of the above circumstances, and an object thereof is to provide a photocatalytic functional material in which a functional material having good photocatalytic activity can be prepared with a low temperature heat treatment, and the surface of the functional material has a high mechanical strength. Means for solving the problem In order to solve the above problems, the photocatalytic functional material of the present invention comprises a surface layer (a photocatalytic functional layer) containing a photocatalyst, an electron-trapping metal, and a photo-degradation-resistant matrix. In the present invention, a mechanism of photocatalytic functions such as deodorant activity, antimicrobial activities, and the like, is shown although almost all the part of the photocatalyst (particles, and the like) in the photocatalyst functional layer are covered by the photodegradation-resistant matrix (a thermosetting resin, and the like) as described below. A photocatalytic reaction on the photocatalyst is considered to proceed as follows. First of all, as the first step, the following reaction in which a photon decomposes to an electron and a positive pore occurs. hv → h + + e - Next, the generated positive pore reacts with oxygen or water in air or in the layer to form an active oxygen species. The chemical formula for the reaction with water is shown below. H 2 O → H + + OH - OH - + h + → OH. Here, the generated active oxygen species OH· acts on a bad smell component or bacteria to show a deodorizing property or an antimicrobial property. Provided that the reaction of the formula (3) competes with the following reaction wherein the positive pore and an electron combine again to return to a photon as shown in the formula (4) below. h + + e - → hv Subsequently, the case where the photocatalyst particles are exposed to air is considered. In this case, oxygen or water in air can directly react with a photocatalyst so that oxygen or water exists on the photocatalyst particles in addition to positive pores and electrons when the decomposition reaction of light represented by the formula (1) is caused. In this case, the formula (3) and the formula (4) become competing reactions so that active oxygen is formed by the formula (3) with a certain possibility (about 20% or so in the case of an anatase type titanium oxide). According to the action of the active oxygen, a photocatalytic reaction such as deodorization, antimicrobial property, and the like, is to be caused. Next, the case where the photocatalytic particle is completely covered by a matrix in the state where no electron-trapping metal exist around the surroundings is considered. The photocatalyst is covered by a matrix so that oxygen or water in air cannot directly get in contact with the photocatalyst. Accordingly, for reacting oxygen or water with a positive pore according to the formula (3), it is necessary to diffuse the oxygen or water in air onto the photocatalyst, diffuse the positive pore to the outermost layer of a layer in which the oxygen or water exists, or cause both of the above diffusion. For this reason, an induction time is caused. On the other hand, an electron already exists on the photocatalyst when the decomposition reaction of a photon occurred. Thus, before causing the above diffusion, that is, during the induction time, the reaction due to the formula (4) occurs, and thus, the active oxygen generating reaction due to the formula (3) seldom occurs. Thus, when almost all part of the photocatalyst is covered by the matrix in the state that electron-trapping metals are not present at the surroundings, an active oxygen occurs with a certain possibility only at the portion where the photocatalyst is exposed. Thus, the amount of the formed active oxygen is little, whereby sufficient photocatalytic function such as deodorization, antimicrobial property, and the like, cannot be exhibited. On the other hand, when electron-trapping metals (ion, particle, and the like) exist in the neighborhood of the photocatalyst, even when the photocatalyst is completely covered by the matrix, electrons formed by the formula (1) are captured by these metals so that the recombination reaction of the formula (4) hardly occurs whereby positive pores remain for a long period of time without disappearing. Accordingly, even when the photocatalyst is covered by the binder and the active oxygen forming reaction of the formula (3) has an induction time for the reason as mentioned above, the positive pores become difficultly extinct by the reaction according to formula (4) whereby the active oxygen formation according to formula (3) occurs after the induction time. According to the above mechanism, since the electron-trapping metal is included in the photocatalyst function layer, the photocatalytic functions such as deodorization, antimicrobial property, and the like, are exhibited although almost all the portion of the photocatalyst is covered by the photodegradation-resistant matrix. Here, the electron-trapping metal according to the present invention is explained. In Fig. 12, potential energy levels of valence electron bands and conduction bands of various kinds of semiconductors are shown ("Photocatalyst", Asakura Shoten, p. 54, 1988). When light is irradiated, electrons at the valence electron band are excited to the conduction band, and an electron having a potential energy level at the lower end of the conduction band and a positive pore having a potential energy level at the upper end of the valence electron band are formed. And when the potential energy level possessed by the positive pore is present at the positive side of that of the oxygen formation level O 2 /H 2 O (+1.22V), the positive pore accepts an electron from H 2 O to form O 2 . Similarly, by forming an active oxygen and causing oxidation decomposition of a gas such as bad smell component(s), and the like, the photocatalytic functions such as deodorization, antimicrobial property, and the like, are exhibited. However, since only the positive pores are consumed, the possibility of recombination between the positive pore and the electron becomes high whereby the active oxygen is hardly formed. In order to decrease the possibility of recombination between the positive pore and the electron, it is necessary to effectively capture the electron and the electron is consumed in the other reaction similarly in the positive pore. For causing the electron to be consumed, it is necessary that reactions which are on the positive side of the potential energy possessed by the electron and on the negative side of the oxygen forming level shall be caused simultaneously. An effective matter as the reaction agent is a reduction reaction of a metal having a formation level on the positive side of the potential energy level possessed by an electron, i.e., a reduction reaction of an electron-trapping metal ion. Incidentally, the reduced metal is oxidized again by an active oxygen so that all the electron-trapping metal ions are never consumed. In Table 1, potential energy levels possessed by the electrons of various kinds of photocatalysts, and potential energy levels of typical reactions (reduction reactions) of accepting electrons are shown. From Table 1, when the photocatalyst is titanium oxide, the potential energy level possessed by the electron is -0.1 V, so that, in this case, as an electron-trapping metal ion, a metal having a formation level.on the positive side of the above, i.e., in particular Cu and Ag, can be suitably utilized. From this consideration, it can be considered that the electron-trapping metal has a large effect when it is added in a layer in the state of an ion. As a suitable value of the amount to be added, it is sufficient with an amount of 0.006% by weight in at least the uppermost layer (an ultraviolet ray reaching depth) of the layers from the experimental facts (Example 2). Here, the ultraviolet ray reaching depth means a depth in which the ultraviolet ray is capable of reaching without being absorbed by the surface layer. An ultraviolet ray absorbing coefficient α of a semiconductor band is represented by α ≒ (E - Eg) 1/2 when a wavelength of light has a slightly larger energy E (= h/λ, wherein h is a Planck's constant and λ is a wavelength of light) than a forbidden width. Here, Eg is a forbidden band width of the semiconductor band. A spectral reaching depth d in the semiconductor band is represented by a reciprocal of α. Accordingly, it is represented by d ≒ (h/λ - Eg) -1/2 . The surface layer of the present invention comprises a photocatalyst which is a semiconductor, an anticorrosive matrix and metal. Among these, when ultraviolet ray absorption by the photocatalyst is considered to be large, and when a volume ratio of the photocatalyst in the surface layer is made x, the ultraviolet ray reaching depth dv is an amount represented by dv ≒ x -1/3 · (h/λ - Eg) -1/2 . In Table 2, forbidden band widths of representative photocatalysts are shown. Photocatalyst Forbidden band with (ev) Photocatalyst Forbidden band width (ev) TiO 2 3.0 CdTe 1.4 ZnO 3.2 WO 3 2.8 SrTiO 3 3.2 Fe 2 O 3 2.3 CdS 2.4 MoS 3 1.8 GaP 2.3 Bi 2 O 3 2.6 SiC 3.0 SnO 2 3.5 CdSe 1.7 InP 1.3 In the present invention, the shape of the photocatalyst is particulate. Typically it consists of inorganic crystalline particles having a photocatalytic function. Incidentally, in the photocatalytic functional layer, a minute amount of particles having no photocatalytic function may be contained in addition to the above particles. For example, there may be mentioned a filler such as metal or an oxide thereof to be added for increasing surface smoothness, and the like. The degree of crystallinity of the photocatalyst particle is a degree in which a maximum peak of the crystal is detected when the photocatalyst particle peeled off from the photocatalyst functional layer is measured by the powder X-ray diffraction under the conditions of 50 kV-300 mA. As an example of the photocatalyst particles, there may be mentioned oxide and non-oxide semiconductors such as TiO 2 , ZnO, SrTiO 3 , Fe 2 O 3 , CdS, CdSe, WO 3 , FeTiO 3 , GaP, GaAs, GeAs, RuO 2 , MoS 3 , LaRhO 3 , CdFeO 3 , Bi 2 O 3 , MoS 2 , In 2 O 3 , CdO, SnO 2 , SiC, InP, and the like. Among these, TiO 2 , ZnO, SrTiO 3 , CdS, CdSe, GaP, MoS 3 , SiC, and the like have the position of the conductive band at higher than the hydrogen generating potential and the upper end of the valence electron band at lower than the oxygen generating potential when it is designated by a band model, and thus, when a light with a wavelength having an energy higher than the band gap is irradiated, an active oxygen is generated. Thus, they are excellent in that they show a deodorant function, an antimicrobial function or an antistain function due to decomposition of an organic compound by oxidation. Also, in Fe 2 O 3 , WO 3 , SnO 3 and Bi 2 O 3 , when these are made fine particles with a particle size of 10 to 100 A or so, the position of the conductive band is moved to an upper portion so that it can be considered to show a deodorant function, an antimicrobial function or an antistain function same as above. Among these, TiO 2 (anatase type, rutile type), Fe 2 O 3 , ZnO, SnO 2 , and the like are available as cheap starting materials, and further an anatase type TiO 2 and SnO 2 are more preferred in that fine particles having higher activity can be easily obtained. The inorganic particles having photocatalytic function of the present application may be used either as any one kind of these alone or in combination of two kinds or more by mixing. In the present invention, the photodegradation-resistant matrix is a thermosetting resin. In this resin, a resin in which a side chain is decomposed by light but a main chain is not decomposed is included. Examples of the photodegradation-resistant matrix are as mentioned below. Hardly decomposable resins: A tetrafluoroethylene resin, a tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer, an acrylic silicon resin, and the like. Resins in which a side chain is partially decomposed but a main chain is not decomposed: A siloxane resin represented by the average compositional formula: R 1 mSi(OR 2 )n(OH)pO(4-m-n-p)/2 (R 1 is an organic group, R 2 is an alkyl group, 0≤m<4, 0≤n<4, 0<m+n<4, 0≤p<4, 0<m+n+p<4). R 1 or R 2 portion is decomposed by photooxidation. Silazane resin and the like. As the thermosetting resin, a silicon resin, a fluoride resin, and the like are mentioned, and a colored one may be used. The electron-trapping metal (particles and the like) is supported and exposed at a surface of a mixture layer of the photocatalyst particles and photodegradation-resistant matrix. By so positioning the metal particles as to contact them with the air outside, a reaction based on the photocatalytic function such as a deodorant reaction and the like can proceed rapidly according to the catalytic function by the metal particles themselves at irradiation of light. For example, when a decomposition reaction by oxidation of a bad odor gas is mentioned as an example, the bad odor gas is adsorbed to the metal particles exposed to the surface, and then an active oxygen formed based on the photocatalytic function and the bad odor gas undergoes a surface reaction on the surface of the photocatalytic functional layer to decompose the bad odor gas. This reaction (cycle) continuously proceeds to promote the reaction, and the photocatalyst and the metal particles cause no chemical change in this cycle. Accordingly, this reaction is a catalytic reaction. Also, by contacting the metal particles with the air outside, even when light is not irradiated, a function possessed by the metal particles can be expected. That is, the metal particles (copper and the like) have a function of adsorbing a bad odor gas such as methyl mercaptane and the like so that they have a function of deodorant and the like for a certain period of time. However, in this case, deodorant activity is effected by adsorption of the bad odor component so that when the adsorbed amount exceeds the saturation amount for adsorption, the effect is lost. Therefore, when it is used for a long period of time, it is preferred to use photoirradiation in combination. Further, in a metal such as silver and the like, the metal itself has a certain degree of antifungal activities so that it is preferred. In the present invention, it is preferred that a mixing ratio (a resin weight/(a resin weight + a photocatalyst weight)) of a thermosetting resin and a photocatalyst in a photocatalytic function layer is 5 to 80%. Further, the ratio is more preferably 10 to 50%. This is because, if the ratio is 5% by weight or less, abrasion resistance of the surface is not sufficient, while if it is 80% by weight or more, the amount of the photocatalyst particles is too little so that the photocatalytic function is not sufficient and there is a fear of not obtaining sufficient odor-proof and antifungal activities as a photocatalytic functional material. When the ratio is 10% or more, the abrasion resistance is more excellent and' when it is 50% or less, the antifungal activities (R30) are good. The photocatalytic functional material which is one embodiment of the present invention comprises having a substrate, and a photocatalytic functional layer fixed on the substrate surface and containing a photocatalyst, an electron-trapping metal, and a photodegradation-resistant matrix. Here, the material of the substrate may be basically any material such as a chinaware, ceramics, enamel, metal, glass, thermosetting resin, thermoplastic resin or a composite material thereof. The shape of the substrate may be any shape and may include a simple shape material of a spherical, a columnar, a cylindrical, a plate material such as a tile, wall material, floor material and the like, or a complex shape material of hygiene earthenware, a washstand, a bathtub, tableware, a pan and the like. The thickness of the photocatalytic functional layer is preferably 0.1 to 20 µm, and more preferably 0.1 to 5 µm, most preferably 0.2 to 1 µm. If it is less than 0.1 µm, there is a tendency that a sufficient photocatalytic activity is not shown. If it exceeds 5 µm, surface gloss of the substrate may be impaired. If it exceeds 20 µm, cracking is likely caused in the layer. Here, the layer thickness is the thickness of that layer in which the element(s) inherently contained in the particles having photocatalytic activity is (are) present when elemental analysis of a cross-section of the surface of the substrate is carried out by EDX, and the like. This photocatalytic functional layer may be formed directly on the substrate, or may be formed via an intermediate layer comprising a binder. A layer comprising a binder has a higher film strength and excellence in adhesion than a film comprising a mixture of a photodegradation-resistant matrix and photocatalyst particles so that, by interposing such an intermediate layer, the substrate and the photocatalytic functional layer can be firmly bound and peeling resistance can be improved. It is not necessary to use the same kind of intermediate layer as the matrix (resin and the like) in the photocatalytic functional layer. Accordingly, for example, when the photodegradation-resistant matrix is made of a resin having a large photodegradation resistance, a resin to be added may be formed of a resin having a slightly inferior photodegradation resistance or a resin with a low cost, or a colored resin may be used to provide an aesthetic value. Also, by interposing such an intermediate layer, the amount of the photodegradation-resistant matrix (a thermosetting resin and the like) in the photocatalytic functional layer can be reduced and the distribution of the photocatalyst particles can be concentrated at the outermost surface or in the neighbourhood thereof so that photocatalytic activity can be more easily shown, and functions of antimicrobial activity, deodorant activity and the like are improved. Here, the binder is preferably one which does not deteriorate when in contact with the photocatalyst in the photocatalytic functional layer. Examples of the binder are as follows. A siloxane resin, a silazane resin, a fluorine resin (a tetrafluoroethylene resin, a tetrafluoroethylene-hexafluoro-propylene copolymer, a tetrafluoroethylene-hexafluoropropyl-ene-vinylidene fluoride copolymer, a fluorovinyl resin, a fluorovinylene resin, a chlorotrifluoroethylene resin, a vinyl ether-fluoroolefin copolymer, a vinyl ester-fluoro-olefin copolymer and the like) an acrylic-silicon resin, a silica type glass, a boron type glass, glaze, flit, and the like. The photocatalytic functional film of the present invention comprises a substrate in a film state having flexibility, a photocatalyst and an electron-trapping metal, and a photocatalytic functional layer containing a photodegradation-resistant matrix. For example, this film is used when functions such as deodorant, antimicrobial activities and the like are added to building materials comprising a laminated steel plate such as a vinyl chloride coated steel plate, and the like. The vinyl chloride coated steel plate is usually prepared by subjecting a steel plate to a melt zinc plating, and after chemical treatment (chromate treatment on a nickel plating), a lamination treatment is carried out. The lamination treatment is carried out by repeating the steps of, after coating an adhesive, adhering various kinds of films such as vinyl chloride film and the like prepared, separately. Accordingly, when a deodorant and antimicrobial film can be prepared, a deodorant and antimicrobial function can be provided to building materials comprising a laminated steel plate by a laminating treatment without requiring specific manufacturing lines. As the preparation process of the film, there may be mentioned, for example, a method of passing a liquid material in which a photocatalyst, a thermosetting resin and an electron-trapping metal are dispersed between hot plates provided at positions opposed to each other with a predetermined distance and slightly inclined to downwards from the liquid material discharging portion. The paint composition of the present invention contains a photocatalyst, an electron-trapping metal, and a photodegradation-resistant matrix in a fluid state. When the functions such as deodorant, and antimicrobial activities and the like are desired to be newly added to, for example, already installed tiles, and the like in situ , this paint composition is used. Solution A in which the main agents of a photocatalyst and a two-pack type thermosetting resin, and electron-trapping metals are dispersed, and Solution B containing a curing agent of the thermosetting resin are prepared and coating is carried out by mixing these solutions in situ . Here, the thermosetting resin is a room temperature curing type, it can be widely used, whether outdoors or indoors. One example for preparing the paint composition is as follows. Preparation of Solution A is, for example, to prepare a photocatalyst sol, a main agent of a thermosetting resin (for example, silica sol) and an electron-trapping metal (a solution in which an aqueous copper acetate solution is photoirradiated), and they are mixed. As Solution B, a curing agent which can cause curing polymerization reaction with the main agent in Solution A is prepared (for example, trimethoxymethylsilane when the main agent in Solution A is a silica sol). Next, a preparation method of the photocatalytic functional material of the present invention is explained. Basic procedures are carried out as follows. (1) preparing a first liquid material containing a photocatalyst and a thermosetting resin, (2) applying said first liquid material to the surface of a substrate, (3) curing said first liquid material after application to the surface of the substrate, (4) preparing a second liquid material containing an electron-trapping metal, (5) applying said second liquid material to the surface of the cured catalyst-resin mixture layer, and (6) irradiating ultraviolet rays to the surface to which said second liquid material is applied to support said metal to said surface. In the above-mentioned steps (1) and (2), a liquid material containing a main agent of a thermosetting resin is prepared, then the mixture is applied to the surface of the substrate. Also, in the above steps, by using a photocurable resin in place of the thermosetting resin, light containing ultraviolet ray may be irradiated in place of subjecting the substrate to which the liquid material is coated to heat treatment. By employing such a constitution, it is not necessary to expose the photocatalyst (particles, and the like) to contact with outer air. Thus, when the material is coated onto the substrate, it is not necessary to separately carry out the step of coating the photocatalyst particles and the step of coating the photodegradation-resistant matrix, and it is possible to coat a material in one step by, for example, mixing and kneading the photocatalyst particles and the binder. Accordingly, simplification of the steps can be realized to reduce manufacturing costs. In the preparation method of the present invention, a step of diluting a suspension of the photocatalyst and the resin with a solvent may be added. The diluent to be used here is to be added for the purpose of lowering viscosity (0.1 to 10 cps or so) and making coating of the material to the substrate easy. It may be basically any material so long as the purpose can be accomplished. For example, ethanol, propanol, water, and the like may be mentioned. Here, a liquid material which hardly causes aggregation of the suspension can be formed by carrying out a step of adding a thermosetting resin to a mixture, a step of diluting the suspension of the mixture comprising the above-mentioned photocatalyst and the resin with a solvent, and a step of adding a curing agent to the above-mentioned diluted solution in this order. A drying step may be inserted between the step of coating the liquid material to which a 'curing agent is added to a substrate, and the step of curing the liquid material by heating. Basically any method of coating liquid material to which a curing agent is added to a substrate may be used but a spray coating method or a roll coating method is relatively simple and easy. The curing step by heating may be carried out at a low temperature of less than 100 °C for a long time or may be carried out at 100 °C or more and less than a heat resistant temperature of the substrate and the thermosetting resin for a short time. In general, the photocatalyst particle has a larger specific gravity than that of the thermosetting resin. Thus, it is desired to carry out the heat treatment at 100 °C or more and less than the heat resistant temperature of the substrate and the thermosetting resin for a short time since there is no fear of burying the photocatalyst particles at the lowermost portion of the substrate surface. In the method of supporting the electron-trapping metal to the photocatalytic functional layer, a mixed layer of the photocatalyst and the resin is formed on the substrate. Thereafter, a liquid containing the electron-trapping metal is applied (coating and the like) onto the mixed layer and light containing ultraviolet ray is irradiated to the coated surface to support the metal to the surface of the substrate. Here, as the metal-containing solution, those as mentioned above can be utilized. As the solvent of the coating solution, ethanol is preferred because it contributes to improvement in productivity of the metal coating step since drying speed is fast as compared with water, because it is capable of improving the supporting efficiency of metal since surface tension is low as compared with water and wettability is good, and because it is harmless, unlike other volatile solvents such as ether, acetone, methanol and the like. The step of supporting the metal to the surface of the support by irradiating light containing ultraviolet ray to the metal coated surface may be carried out after drying the coated metal-containing solution. By employing such a step, supporting efficiency of the metal can be improved as compared with the case where no drying is carried out. A light source of irradiating light containing ultraviolet ray may be any one having an ultraviolet intensity with a degree which does not impair the substrate or the resin. For example, there may be used a fluorescent light, a BLB lamp, an ultraviolet lamp, a xenone lamp, a mercury lamp, sun light and the like. However, when the irradiation time takes several hours, the ultraviolet intensity is preferably less than 1.7 mW/cm 2 . Accordingly, in this case, a mercury lamp, and the like are generally not suitable. The method of irradiating light containing ultraviolet ray is preferably carried out by providing the light so that it is vertically incident upon a sample. This is because then the irradiation efficiency of light is good. An irradiation time of light containing ultraviolet ray is suitably several seconds to several hours or so. If it is too short, the above-mentioned metal is not sufficiently reduced nor supported, while if it is too long, the electron-trapping effect of the above-mentioned metal particles is weakened, and when a light source with a large ultraviolet intensity is used, there is a fear,that the substrate or the resin is impaired. A method of irradiating light containing ultraviolet ray is also not basically limited, but firstly, it is preferably irradiated from the upper portion of the apparatus. This is because absorption of the ultraviolet ray by the apparatus is little. Secondly, the distance between the light source and the apparatus is preferably several cm to several 10 cm or so. This is because if it is too close, there is a fear of drying the upper surface of the sample solution due to heat emitted by the light source, while if it is too far, intensity is lowered. The irradiation time is different depending on the intensity of the light source, but when irradiation is carried out for several seconds to several 10 minutes or so, metals are firmly adhered to the photocatalyst particles. Brief description of the drawings Fig. 1 is a graph showing the relationship between the added amount of a thermosetting resin and abrasion resistance in Examples 1 and 2. Fig. 2 is a graph showing the relationship between the added amount of a thermosetting resin and photoactivity in Examples 1 and 2. Fig. 3 is a graph showing the relationships between the added amount of a thermosetting resin, and abrasion resistance and photoactivity in Example 3. Fig. 4 is a graph showing the relationships between the added amount of a thermosetting resin, and abrasion resistance and photoactivity in the test of Example 4. Fig. 5 is a graph showing the relationship between the resin ratio of the photocatalytic functional layer and photoactivity in Example 5. Fig. 6 is a graph showing the relationship between the resin ratio of the photocatalytic functional layer and the survival ratio of Escherichia coli in Example 5. Fig. 7 is a graph showing deodorant activity of a sample to which no metal is added in the test of Example 6. Fig. 8 is a graph showing deodorant activity of a sample to which copper is added in the test of Example 6. Fig. 9 is a graph showing the relationship between the film thickness of the photocatalytic functional layer and glossiness in the test of Example 6. Fig. 10 is a drawing showing the results of Auger analysis at the surface of the sample in Example 1. Fig. 11 is a graph showing the relationship between the weight ratio of titanium oxide and the surface hardness of the photocatalyst functional layer in Example 3. Fig. 12 is a drawing showing the relationship between the band structure of the photocatalyst and an energy level. Examples Example 1 (Copper, coating method) To a titanium oxide sol (elute concentration 10% by weight, nitric acid dispersion type, pH 0.8, TA15 available from Nissan Chemical Co.) having an average particle size of 0.01 µm was added a silica sol (elute concentration 13% by weight, Gulaska A available from Nippon Synthetic Rubber) as a main agent, and the mixture was diluted with propanol. Thereafter, trimethoxymethylsilane (Gulaska B available from Nippon Synthetic Rubber) was added as a curing agent, and the solution was coated to an aluminum substrate with a size of 10 cm square. Thereafter, it was heated to 150 °C to solidify and then cooled. Results of Auger analysis of the sample surface at this stage are shown in Fig. 10. (a) represents the analytical results at the uppermost layer, and (b) and (c) each represent the analytical results at the inner portions of 200 Å and 2,000 Å from the surface layer, respectively. From Fig. 10, titanium can hardly be observed at the uppermost layer, and when the matrix layer is formed by curing polymerization reaction as in the present invention, it was found that the titanium oxide particles exist at the uppermost layer with a substantially not exposed state. Accordingly, in the case of the present invention, different from the usual surface reaction catalyst other than the photocatalyst, an electron-trapping activity is added by addition of a metal whereby activities of deodorant activity and decomposing gas and the like are shown even when the catalyst is not exposed at the surface. Next, on the surface of the cured catalyst-resin mixture layer was coated an aqueous copper acetate (molecular weight 199.65), and then, light from a BLB lamp with 0.5 mW/cm 2 was irradiated for 30 seconds to obtain a sample. The film thickness of the thus obtained photocatalytic functional layer was about 0.8 µm and the crystal system of titanium oxide was anatase. The weight ratio of silica sol and trimethoxymethylsilane was made 3 : 1. Also, an amount of copper supported to the surface of the sample was made 0.5 to 3 µg/cm 2 (corresponding to 0.006 to 0.04% by weight based on the weight of the solid components of titanium oxide and the resin). As for the resulting sample, deodorant activity and peeling resistance were evaluated. As for the evaluation of deodorant activity, by the method shown below, methyl mercaptane was used as a bad odor gas and evaluation was carried out by measuring R30'. R30' is an evaluation index of deodorant activity obtained as mentioned below. First, a methyl mercaptane gas with a concentration of 3 ppm at dark was injected into 11 liters of a glass apparatus in which a sample was charged, and the sample was allowed to stand for one day to sufficiently adsorb the gas to the sample. Next, light was irradiated (a light source (a BLB lamp 4W) was arranged at a distance of 8 cm from the sample) to the sample to photodecompose the adsorbed gas. Next, a methyl mercaptane gas was newly injected into the apparatus at an initial concentration of 3 ppm, and change in concentration after 30 minutes at dark was measured. As for peeling resistance, sliding abrasion using a plastic eraser was carried out, and change in appearance was compared and evaluated. Evaluation standard is shown below. o ○: No change after 40 times back and forth ○: xScratching occurs after sliding 10 times or more and less than 40 times and the photocatalyst containing layer is peeled off Δ: Scratching occurs after sliding 5 times or more and less than 10 times and the photocatalyst containing layer is peeled off X: Scratching occurs after sliding less than 5 times and the photocatalyst containing layer is peeled off The results are shown in Figs. 1 and 2 with black points. As shown in Fig. 1, when a layer comprising only photo-catalytic particles (anatase particles) is formed on the surface of the substrate (resin 0%), peeling resistance was X, but when 20% by weight or more of the resin is added based on the total weight of the photocatalytic particles and the resin, peeling resistance was improved to ○. Further, when 60% by weight or more of the resin is added based on the total weight of the photocatalytic particles and the resin, peeling resistance was improved to o ○. As shown in Fig. 2, deodorant activity, in the case of the resin (100%) alone, shows only a value for R30' of 10% or less which is considered to be due to the adsorption activity of copper. However, when the photocatalyst particles are added in an amount of 80% by weight or more (the resin amount of 20% by weight or less), the deodorant activity became good, exceeding 50%. Example 2 (having an intermediate layer, copper, coating method) A liquid material in which silica sol and trimethoxymethylsilane were mixed with a weight ratio of 3 : 1 and an elute concentration of 20% by weight was coated to an aluminum substrate with a size of 10 cm square and dried at 150 °C to form a resin layer (an intermediate layer) with a film thickness of about 5 µm. Thereafter, onto the surface of the intermediate layer, a photocatalytic functional layer comprising titanium oxide, a resin and copper was formed in the same manner as in Example 1. The film thickness of the photocatalytic functional layer was about 0.3 µm. As for the resulting sample, deodorant activity and peeling resistance were evaluated. The results are shown in Figs. 1 and 2 with white-blanked points. As shown in Fig. 1, by interposing the siloxane resin layer between the substrate and the photocatalytic functional layer, peeling resistance became ○ by addition of 5% by weight or so of the matrix resin based on the total weight of the photocatalyst particles (anatase particles) and the matrix resin. Further, by addition of 10% by weight or more of the matrix resin based on the total weight of the photocatalyst particles and the matrix resin, peeling resistance became o ○. As shown in Fig. 2, when the photocatalyst particles are added in an amount of 50% by weight or more, deodorant activity became 90% or more whereby good results are shown. In conclusion, when a siloxane resin layer is interposed at an intermediate portion, it was found that the above-mentioned two characteristics showing contradictory tendency depending on the ratio of both materials in the mixed layer comprising the photocatalyst particles and the resin can be easily harmonized. It was found that good results are shown particularly when the amount of the matrix resin based on the total weight of the photocatalyst particles and the matrix resin is 5% by weight or more and less than 80% by weight, preferably 5% by weight or more and 50% by weight or less. Example 3 (Copper, mixing method, intermediate layer present - Comparative Example, included for reference and/or comparison only) First, a resin layer with a film thickness of about 5 µm was formed in the same manner as in Example 2. Next, an aqueous copper acetate (molecular weight 199.65) solution and the titanium oxide sol used in Example 1 were mixed. Next, the silica sol used in Example 1 was added to the mixture, the resulting mixture was diluted with ethanol and then, trimethoxymethylsilane used in Example 1 was added to obtain a liquid material. This liquid material was coated to an aluminum plate with a size of 10 cm square, and dried at 150 °C to form a photocatalytic functional layer with a film thickness of about 0.3 µm whereby a sample was obtained. Here, the weight ratio of the silica sol and trimethoxymethylsilane was 3 : 1. Also, the crystal system of the titanium oxide was anatase. The weight of copper acetate solid component based on the total weight of the resin weight and the photocatalyst weight was 2%. As for the resulting sample, deodorant activity, peeling resistance and surface hardness were evaluated. The surface hardness was evaluated by scratching the surface of a member with pencils having a different hardness from 6B to 9H and judging the hardness by the pencil hardness required to scratch the surface. Results regarding the deodorant activity and peeling resistance are shown in Fig. 3. In this case, in the same manner as in Example 2, by interposing the siloxane resin layer at an intermediate portion, peeling resistance became ○ by addition of 5% by weight or so of the matrix resin based on the total weight of the photocatalyst particles and the matrix resin. Further, by addition of 10% by weight or more of the matrix resin based on the total weight of the photocatalyst particles and the matrix resin, peeling resistance became o ○. Also, as for deodorant activity, when the photocatalyst particles are added in an amount of 50% by weight or more, it became 80% or more whereby good results are shown. In conclusion, in the same manner as in Example 2, it was found that good results are shown when the amount of the matrix resin based on the total weight of the photocatalyst particles and the matrix resin is 5% by weight or more and less than 80% by weight, preferably 5% by weight or more and 50% by weight or less. Also, results regarding the surface hardness are shown in Fig. 11. When the amount of the matrix resin based on the total weight of the photocatalyst particles and the matrix resin in the mixed layer comprising the photocatalyst particles and the resin is 10% by weight or more, the surface hardness became a sufficient hardness of 5B or more, and when it is 60% by weight or more, the surface hardness became a more sufficient hardness of H or more. Example 4 (Copper, mixing method, intermediate layer present, photo-irradiation at mixing - Comparative Example, included for reference and/or comparison only) First, a resin layer with a film thickness of about 5 µm was formed on an aluminum substrate with a size of 10 cm square in the same manner as in Example 2. Next, the aqueous copper acetate solution and the titanium oxide sol used in Example 3 were mixed and the light of a BLB lamp with 0.5 mW/cm 2 was irradiated for 15 minutes while stirring. Thereafter, the silica sol used in Example 1 was added, and after the resulting mixture was diluted with ethanol, trimethoxymethylsilane used in Example 1 was added to obtain a liquid material. This liquid material was coated on the resin layer of the above-mentioned substrate, and dried at 150 °C to form a photocatalytic functional layer with a film thickness of about 0.3 µm whereby a sample was obtained. Here, the weight ratio of the silica sol and trimethoxymethylsilane was 3 : 1. Also, the crystal system of the titanium oxide was anatase. The weight of copper acetate solid component based on the total weight of the resin weight and the photocatalyst weight was 2%. As for the resulting sample, deodorant activity and peeling resistance were evaluated. The results are shown in Fig. 4. In this case, in the same manner as in Example 2, by interposing the siloxane resin layer at an intermediate portion, peeling resistance became ○ by addition of 5% by weight or so of the matrix resin based on the total weight of the photocatalyst particles and the matrix resin. Further, by addition of 10% by weight or more of the matrix resin based on the total weight of the photocatalyst particles and the matrix resin, peeling resistance became o ○. Also, as for deodorant activity, when the photocatalyst particles are added in an amount of 50% by weight or more, it became 90% or more whereby good results are shown. In conclusion, in the same manner as in Example 2, it was found that good results are shown when the amount of the matrix resin based on the total weight of the photocatalyst particles and the matrix resin is 5% by weight or more and less than 80% by weight, preferably 5% by weight or more and 50% by weight or less. Example 5 (Copper, mixing method, changing copper concentration - Comparative Example, included for reference and/or comparison only) First, a resin layer with a film thickness of about 5 µm was formed on an aluminum substrate with a size of 10 cm square in the same manner as in Example 2. Next, the aqueous copper acetate solution and the titanium oxide sol used in Example 3 were mixed, and then, the silica sol used in Example 1 was added. After the resulting mixture was further diluted with ethanol, trimethoxymethylsilane used in Example 1 was added to obtain a liquid material. This liquid material was coated on the resin layer of the above-mentioned substrate, and dried at 150 °C to form a mixed layer with a film thickness of about 0.1 µm whereby a sample was obtained. Here, the weight ratio of the silica sol and trimethoxymethylsilane was 3 : 1. Also, the weight ratio of the solid component weight (resin weight) of the silica sol and trimethoxymethylsilane and the solid component weight of the titanium oxide sol (photocatalyst weight) was changed variously (in a ratio of the resin weight based on the total weight of the resin weight and the photocatalyst weight, 0%, 10%, 20%, 50%, 80%, 90%, 100%), and the solid component weight of copper acetate based on the total weight of the resin weight and the photocatalyst weight was also changed variously (0%, 2%, 10%) to carry out the tests whereby deodorant activity and peeling resistance were evaluated. Here, the deodorant activity was evaluated by R30. R30 can be specifically obtained by arranging a film-forming surface of a sample in 11 liters of a glass apparatus with a distance of 8 cm from a light source (a BLB lamp, 4W), injecting a methyl mercaptane gas into the apparatus at an initial concentration of 3 ppm, and measuring change in concentration after 30 minutes at photoirradiation and at dark. Evaluation of antibacterial activity was carried out by supporting 0.15 ml of 10 5 CFU/ml Escherichia coli on the sample surface, and after irradiating 0.02 mW/cm 2 of a FL lamp for 30 minutes, recovering bacteria to obtain the survival ratio of bacteria. Evaluation index is shown below. +++: Survival ratio of bacteria of less than 10% ++ : Survival ratio of bacteria of 10% or more and less than 30% + : Survival ratio of bacteria of 30% or more and less than 70% - : Survival ratio of bacteria of 70% or more In Fig. 5, results of deodorant activity are shown. At a film thickness of the photocatalytic functional layer of about 0.1 µm, when copper was not added, the R30 value was less than 50% even at a resin content of 0%. However, when the photocatalyst weight based on the total amount of the resin weight and the photocatalyst weight exceeds 50% by adding at least 2% of copper, the R30 value exceeded 50%. Also, when 10% of copper was added, even when the photocatalyst weight based on the total amount of the resin weight and the photocatalyst weight was 20% or so, The R30 value exceeded 50% to show good value. In Fig. 6, results of antibacterial activity are shown. At a film thickness of about 0.1 µm, when copper was not added, even when the photocatalyst weight based on the total amount of the resin weight and the photocatalyst weight was increased up to 80%, it did not reach to ++. To the contrary, by adding at least 2% of copper, even when the photocatalyst weight based on the total amount of the resin weight and the photocatalyst weight was decreased to 10% or so, it showed an antibacterial activity of +++. Example 6 (Effect of film thickness) First, a resin layer with a film thickness of about 5 µm was formed on an aluminum substrate with a size of 10 cm square in the same manner as in Example 2. Next, the aqueous copper acetate solution and the titanium oxide sol used in Example 3 were mixed, and then, the silica sol used in Example 1 was added. After the resulting mixture was further diluted with ethanol, trimethoxymethylsilane used in Example 1 was added to obtain a liquid material. This liquid material was coated on the resin layer of the above-mentioned substrate, and dried at 150 °C to form a photocatalytic functional layer with various film thicknesses whereby samples were obtained. Here, the weight ratio of the silica sol and trimethoxymethylsilane was 3 : 1. Here, the weight ratio of the solid component weight (resin weight) of the silica sol and trimethoxymethylsilane and the solid component weight of the titanium oxide sol (photocatalyst weight) was 50%. The solid component weight of copper acetate based on the total weight of the resin weight and the photocatalyst weight was 2%. With regard to the resulting samples, deodorant activity and glossiness were evaluated. In Fig. 7, experimental results of deodorant activity when no metal had been added, which was measured for comparative purpose are shown. From the figure, if the film thickness does not exceed 3 µm or more, R30 does not exceed 50%. In Fig. 8, experimental results of deodorant activity when copper was added are shown. Here, the white-blank points show the results at photoirradiation and the black-blank points show those at dark. First, from the fact that the white-blank points are more than the black points, it can be found that the R30 value relates not only to adsorption due to copper but also to decomposition due to the photocatalyst. From the figure, it was found that when the film thickness became 0.1 µm or more, R30 became a value of exceeding 50%, and when it became 0.3 µm or more, R30 reached to 80% or more. That is, by adding a metal, sufficient deodorant activity was shown even when the film thickness was less than 3 µm. Also, in Fig. 9, measurement results of glossiness of samples are shown. Here, measurement of the glossiness was carried out by using a glossmeter (manufactured by Nihon Denshoku Kogyo, VGS-10) and measured by the method of JIS Z8741 with an incident angle of 60°. It was found that at the film thickness of 0.5 µm or less, the glossiness is rather good when the mixed layer of the resin and the photocatalyst is present and preferable in terms of appearance. Accordingly, for obtaining good properties in both of deodorant activity and glossiness, it is preferred to add a metal. Example 7 (Silver, mixing method - Comparative Example, included for reference and/or comparison only) First, a resin layer with a film thickness of about 5 µm was formed on an aluminum substrate with a size of 10 cm square in the same manner as in Example 2. Next, an aqueous silver nitrate (molecular weight 170) solution and the titanium oxide sol (elute concentration 10% by weight, nitric acid dispersion type, pH 0.8) used in Example 1 were mixed and the light of a BLB lamp with 0.5 mW/cm 2 was irradiated for 15 minutes while stirring. Next, a silica sol was added to the mixture, the resulting mixture was diluted with ethanol, and then, trimethoxymethylsilane was added to obtain a liquid material. This liquid material was coated on the resin layer of the above-mentioned substrate and dried at 150 °C to form a mixed layer with the film thickness of about 0.3 µm whereby a sample was obtained. Here, the weight ratio of the silica sol and trimethoxymethylsilane was 3 : 1. Also, the crystal system of the titanium oxide was anatase. The weight ratio of the solid component weight (resin weight) of the silica sol and trimethoxymethylsilane and the solid component weight of the titanium oxide sol (photocatalyst weight) was 50%. The solid component weight of silver nitrate based on the total weight of the resin weight and the photocatalyst weight was 30%. With regard to the resulting sample, antibacterial activity and peeling resistance were evaluated. As the results, the antibacterial activity was +++ and the peeling resistance was o ○. Example 8 (one pack type) First, a resin layer with a film thickness of about 5 µm was formed on an aluminum substrate with a size of 10 cm square in the same manner as in Example 2. Next, the aqueous copper acetate solution and the titanium oxide sol used in Example 3 were mixed, and then, the trimethoxymethylsilane used in Example 1 was added to the mixture, and the resulting mixture was diluted with ethanol to obtain a liquid material. This liquid material was coated on the resin layer of the above-mentioned substrate, and dried at 150 °C to form a photocatalytic functional layer with the film thickness of about 0.5 µm whereby a sample was obtained. The weight ratio of the solid component weight (resin weight) of the trimethoxymethylsilane and the solid component weight of the titanium oxide sol (photocatalyst weight) was 50%. The solid component weight of copper acetate based on the total weight of the resin weight and the photocatalyst weight was 2%. With regard to the resulting sample, deodorant activity and peeling resistance were evaluated. As the results, the deodorant activity was 95% with R30 and the peeling resistance became o ○. Example 9 (Fluoride resin - Comparative Example, included for reference and/or comparison only) To the titanium oxide sol used in Example 1 was added a water-dispersible fluoro resin coating solution (tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride copolymer, elute concentration 50% by weight, available from Sumitomo 3M, THV350C), the resulting mixture was diluted with ethanol to obtain a liquid material. This liquid material was coated on an aluminum substrate with a size of 10 cm square, and dried at 150 °C to form a mixed layer with the film thickness of about 0.5 µm. The weight ratio of the solid component weight (resin weight) of the fluoro resin and the solid component weight of the titanium oxide sol (photocatalyst weight) was 50%. Onto the above-mentioned mixed layer was coated an aqueous copper acetate (molecular weight 199.65) solution, and then, the light of a BLB lamp with 0.5 mW/cm 2 was irradiated for two minutes to obtain a sample. The thus obtained film thickness of the photocatalytic functional layer was about 0.8 µm, and the crystal system of the titanium oxide was anatase. The weight ratio of the silica sol and trimethoxymethylsilane was 3 : 1. Also, the copper amount supported on the sample surface was made 3 to 10 µg/cm 2 (which corresponds to 0.04 to 0.12% by weight based on the solid component weight of the titanium oxide and the resin). With regard to the resulting sample, deodorant activity and peeling resistance were evaluated. As the results, the deodorant activity was 97% with R30 and the peeling resistance became o ○. Example 10 (Enamel substrate) After heating a stainless substrate to 600 °C, glaze, flit was sprayed to prepare an enamel substrate having a size of 10 cm square. To this enamel substrate, an intermediate layer and a photocatalytic functional layer were formed in the same manner as in Example 2. However, the weight of the photocatalyst was 50% based on the total weight of the photocatalyst and the resin. With regard to the resulting sample, deodorant activity (R30) and abrasion resistance were evaluated. As the results, it showed good results in that the deodorant activity was 84% and the abrasion resistance was o ○. Effects of the invention As clearly seen from the above-mentioned explanation, the present invention can provide a photocatalytic functional material which can be produced even by a heat treatment at a lower temperature of less than 300 °C. Also, on the substrate with various forms, photocatalytic function can be added with a simple and easy application method such as in situ adhering or coating. Particularly, a photocatalytic functional material having excellent characteristics in which both of peeling resistance and photocatalytic function are good can be provided, which could never be obtained by the conventional resin type matrix base.

Claims: A photocatalytic functional material comprising a substrate and a photocatalytic functional layer adhering to a surface of the substrate and containing photocatalyst particles, electron-trapping metal and a photodegradation-resistant matrix, wherein, said photodegradation-resistant matrix is a thermosetting resin, said metal is comprised of any one of metals Cu and Ag, and, said metal is supported and exposed at a surface of a mixture layer of said photocatalyst particles and photodegradation-resistant matrix. The photocatalytic functional material according to claim 1, wherein a binder layer resides between said substrate and said photocatalytic functional layer, and wherein said binder layer is adhering to both said substrate and said photocatalytic functional layer. The photocatalytic functional material according to any one of claims 1 and 2, wherein the thickness of said photocatalytic functional layer is 0.1 to 5 µm. The photocatalytic functional material according to any one of claims 1 and 2, wherein the concentration of said electron-trapping metal at the ultraviolet ray reaching depth of said photocatalytic functional layer is at least 0.006% by weight of the combined photocatalytic and photodegradation-resistant matrix. The photocatalytic functional material according to any one of claims 1 and 2, wherein the mixing ratio (resin weight/(resin weight + photocatalyst weight)) of the thermosetting resin and the photocatalyst in said photocatalytic functional layer is 10 to 50%. The photocatalytic functional material according to any one of claims 1 and 2, wherein said substrate is a tile. A method for preparing a photocatalytic functional layer which comprises: preparing a first liquid material containing a photocatalyst and a thermosetting resin, applying said first liquid material to the surface of a substrate, curing said first liquid material after application to the surface of the substrate, preparing a second liquid material containing an electron-trapping metal, applying said second liquid material to the surface of the cured catalyst-resin mixture layer, and irradiating ultraviolet rays to the surface to which said second liquid material is applied to support said metal to said surface.

Inventors: CHIKUNI MAKOTO, HAYAKAWA MAKOTO, WATANABE TOSHIYA, CHIKUNI, MAKOTO, HAYAKAWA, MAKOTO, WATANABE, TOSHIYA
Applicants: TOTO LTD, TOTO LTD.
Application year: 1995
Main classification: B01J35
IPC codes: B01J35