Forming method of thin film having photocatalytic activity

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a method for forming a thin film having photocatalytic activity used for, for example, antibacterial, sterilization, deodorization, etc., and more particularly to a method for forming a thin film having photocatalytic activity using a photocurable sol-gel method.

【0002】

[Conventional technology]

In recent years, the photocatalytic action of photosemi-conductive substances has been used not only as a catalyst for chemical reactions such as photodecomposition of water, but also in many applications such as decomposition and removal of environmental pollutants in water and air, deodorization, antibacterial and sterilization. It is attracting attention. Further, in order to add functions such as antibacterial property, antifouling property and deodorizing property to the base material, a conventional method of forming a thin film containing an anatase-type titanium oxide or the like on the surface of the base material has been used. Various proposals have been made.

【0003】

For example, a photocatalyst powder is applied and fixed on a substrate by spray coating or the like, a metal oxide sol is applied thereto, the metal oxide is gelled by a sol-gel method, and the photocatalyst powder is supported and fixed by a metal oxide gel. A method has been proposed (Japanese Patent Laid-Open No. 5-309267).

【0004】

The metal oxide gel is produced by the sol-gel method in the method described in the above prior art as follows. The metal alkoxide of the metal oxide finally produced, the solvent thereof, and water for hydrolyzing the metal alkoxide are used as raw materials. The reaction in this sol-gel method is as follows.

【0005】

[Chemical 1]

<img file="JPH10235203A_D0001.tif" />【0006】

In reaction (1), metal alkoxide M (OR)_nIs hydrolyzed. Next, as the reaction (2) progresses, the metal oxide MO_{n / 2}Is generated. This metal oxide is a kind of polymer having a -MOMO- skeleton. Therefore, as the reaction (2) progresses, the metal alkoxide solution becomes a sol and eventually gels. After completion of the reaction, the produced metal oxide gel is fired by heating it to several hundred ° C.

【0007】

The firing removes excess functional groups and forms bonds between the compounds having a -MOMO- skeleton. Therefore, a metal oxide thin film is formed as a thin film having sufficient mechanical strength.

【0008】

That is, in the method described in the above prior art, it was necessary to bake at a high temperature of several hundred ° C. after the completion of the reaction (2). Therefore, the base material used had to be able to withstand the firing temperature. Therefore, in the method described in the above prior art, there are restrictions on the base material to be used, and in particular, a base material made of an organic material having insufficient heat resistance cannot be used.

【0009】

[Problems to be Solved by the Invention]

An object of the present invention is to reliably form a thin film capable of exhibiting sufficient photocatalytic performance even on a substrate having insufficient heat resistance, and therefore, to obtain photocatalytic activity with almost no restrictions on the materials constituting the substrate. An object of the present invention is to provide a method for forming a thin film having a thin film.

【0010】

[Means for solving problems]

The invention according to claim 1 is a method for forming a thin film having photocatalytic activity by a photocurable sol-gel method, in which a step of forming an uncured thin film on a substrate and photosemiconduction on the uncured thin film. It is characterized by comprising a step of adhering a sex substance and a step of irradiating the thin film with light to cure the thin film and fixing the photosemi-conductive substance to the thin film.

【0011】

In the invention according to claim 1, preferably, as described in claim 2, a complexing agent that shifts the light absorption wavelength to the long wavelength side is contained in the uncured thin film. Further, in the invention according to claim 1 or 2, titanium dioxide is preferably used as the photosemi-conductive substance as described in claim 3.

【0012】

The details of the present invention will be described below. In the inventions according to claims 1 to 3, film formation is performed by a photocurable sol-gel method. That is, in the conventional sol-gel method, it is necessary to apply a sol solution on a base material, gel it, and then bake it at a high temperature of several hundred ° C. Therefore, there are restrictions on the materials constituting the base material. In view of the above, the present invention is characterized in that the above problem is solved by using the photocurable sol-gel method which does not require the above-mentioned firing.

【0013】

The process of forming a thin film by the photocurable sol-gel method will be described by taking as an example the case where a metal alkoxide is used as a raw material. First, a solvent is added to the metal alkoxide to prepare an alkoxide solution, and water is further added to prepare a solution.

【0014】

Next, the above solution is applied onto the substrate, and unnecessary solvent is removed by volatilization or the like. Next, the metal alkoxide is decomposed by irradiating with light having an absorption wavelength of the metal alkoxide. As a result, the above reactions (1) and (2) proceed, and gelation proceeds. Since this method is photocurable, it does not require a firing step in a general sol-gel method.

【0015】

Therefore, the method for producing a thin film having photocatalytic activity according to claims 1 to 3 does not require a firing step that has been conventionally required, and therefore, the base material is a base material made of an organic resin having low heat resistance. It is also possible to use.

【0016】

The main raw material used when forming a thin film by the photocurable sol-gel method in the present invention is not particularly limited, but a metal alkoxide conventionally used as a main raw material in the photocurable sol-gel method is preferable. Can be used for.

【0017】

Metal alkoxide The metal alkoxide is not particularly limited as long as it can be gelled by the photocurable sol-gel method, and examples of the metal used for the metal alkoxide include A1, Ba, Bi, Ca, Cr, and the like. There are Co, Cu, Fe, La, Mo, Nb, Ni, Pb, P, Si, Sn, Sr, Ti, Ta, V, W, Y, Zr and so on. Further, examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group and the like.

【0018】

Further, as metal alkoxides, for example, aluminum butoxide, aluminum ethoxide, germanium ethoxide, strontium ethoxide, titanium butoxide, titanium ethoxyde, titanium isopropoxide, titanium methoxyde, zirconium butoxide, zirconium ethoxydo, zirconium propoxide, Silicon alkoxide and the like are generally commercially available and easily available, and thus can be preferably used.

【0019】

In selecting the metal alkoxide, it is preferable to consider the solubility of the metal alkoxide in the metal oxide to be finally synthesized and the solvent. Further, the above metal alkoxide may be used alone or in combination of two or more.

【0020】

Further, among the above metal alkoxides, alkoxysilanes are particularly preferably used because they are easy to handle. When alkali resistance is required as chemical resistance, it is preferable to use zirconium alkoxide so that zirconia is contained in the thin film.

【0021】

solvent The solvent used in the invention according to claim 1 is not particularly limited as long as it can dissolve the metal alkoxide, but a solvent that dissolves the metal alkoxide without forming a precipitate is preferable. Further, the invention according to claim 2 is not particularly limited as long as it can dissolve the complexing agent described later and the complex formed by the addition of the complexing agent. Absent.

【0022】

When a precipitate is formed, the mechanical properties of the finally formed thin film may deteriorate, or the thin film itself may not be formed. Examples of the solvent that can be used in the invention according to claims 1 to 3 include methyl alcohol, ethyl alcohol, isopropyl alcohol, ethoxyethyl alcohol, allyl alcohol, ethylene glycol, ethylene oxide, triethanolamine, xylene and the like. ..

【0023】

Coordinator In the invention according to claim 2, a complexing agent is used to shift the light absorption wavelength, and the complexing agent includes β-diketones (R).¹COCH₂COR², However, R¹Is, for example, a methyl group, an ethyl group, a tert-butyl group, etc., and R²Is, for example, a methyl group, an ethyl group, a tert-butyl group, etc., and R¹(May be the same as), β-ketone esters (R)³COCH₂COOR⁴, R³Is, for example, a methyl group, an ethyl group, etc., and R⁴Is, for example, a methyl group, an ethyl group, etc., and R³(May be the same as), or various ethanolamines (NH)_3-X(C₂H₄OH)_X, X is an integer from 1 to 3).

【0024】

Examples of specific compounds of the complexing agent include acetylacetone and benzoylacetone as β-ketones, methyl acetoacetate as β-ketone acid esters, and ethanolamine as ethanolamines. Can be shown.

【0025】

The amount of the complexing agent added is not particularly limited. However, it is preferable to use the complexing agent in the range of 0.5 to 3 mol with respect to 1 mol of the metal alkoxide. If it is less than 0.5 mol, the formation of the chelate by the complexing agent and the metal alkoxide may be insufficient and the thin film may not be formed. On the contrary, if the amount is more than 3 mol, a large amount of impurities are mixed in the reaction system, and the physical characteristics of the formed thin film may be deteriorated.

【0026】

By using the complexing agent, the light absorption wavelength of the metal alkoxide forming the complex with the complexing agent is shifted, and photocuring becomes easy. That is, the wavelength of the light to be irradiated is preferably the absorption maximum wavelength indicated by the chelate bond that causes complex formation, but is not particularly limited as long as photocuring occurs.

【0027】

Further, by combining an appropriate complexing agent and a metal alkoxide, the absorption maximum wavelength is shifted to the long wavelength side, which improves the ease of work and the convenience of the apparatus. That is, since the light absorption wavelength shifts to the longer wavelength side, the selection range of available light sources and optical systems is expanded.

【0028】

The irradiation time of light is not particularly limited, but it is preferable to irradiate the formed complex until it completely reacts because the chemical stability of the thin film can be enhanced. In this case, as an example of the method for measuring the degree of reaction, a method for observing the change in the absorption maximum wavelength spectrum of the thin film coated on the substrate can be mentioned.

【0029】

Photo-semi-conducting material In the inventions according to claims 1 to 3, the photosemi-conductive substance used for exhibiting photocatalytic activity is not particularly limited as long as it has photocatalytic activity. For example, metal oxides such as zinc oxide, titanium dioxide, tungsten oxide, strontium titanate, ferric oxide; metal chalcogenides such as zinc sulfide, cadmium sulfide, lead sulfide, zinc selenide, cadmium selenide; silicon, germanium, etc. Group IV elements; III-V compounds such as gallium-phosphorus, gallium-arsenide, and indium-phosphorus; organic semiconductors such as polyacetylene, polypyrrole, polythiophene, polyaniline, and polyvinylcarbazole can be shown.

【0030】

Among the above photosemi-conductive substances, it is preferable to use a metal oxide such as titanium oxide or tungsten oxide in consideration of chemical stability and availability. Among them, titanium oxide is easily available because it is easily available, and any of amorphous, rutile type and anatase type can be used as the type. However, when the thin film is used for the purpose of antibacterial, antifouling, deodorization, removal of nitrogen oxides, etc., anatase-type titanium oxide is most preferable because the performance of anatase-type titanium oxide is the best.

【0031】

In many cases, titanium oxide, which is generally used as a white pigment, has a low photocatalytic action because its surface is completely coated with alumina or silica, which is not preferable.

【0032】

The above photosemi-conductive substances may be used alone or in combination of two or more. Further, in order to improve the photocatalytic performance, the following conductive substance or the like may be added to the photosemi-conductive substance.

【0033】

Further, the shape and size of the photosemi-conducting substance are not particularly limited, but in the invention according to claim 1, it is necessary to adhere the photo-semi-conducting substance onto the uncured thin film. Therefore, in order to facilitate the adhesion of the photosemi-conductive substance and uniformly disperse it on the thin film, the photosemi-conductive substance is preferably a fine powder.

【0034】

When the photosemi-conductive substance is used as a fine powder, the preferable particle size is 1 nm to 100 μm in diameter. Outside the above range, the dispersibility and adhesion on the thin film may decrease.

【0035】

Further, the photosemi-conducting material may be coated with a porous material and encapsulated. In this case, the porous substance is not particularly limited as long as it is a material that is not easily deteriorated by the photocatalytic action of the photosemi-conductive substance, and for example, an inorganic substance such as silica or alumina or an organic substance such as a fluororesin is used. Can be done. However, considering the light transmittance required for the photocatalytic reaction, a glassy substance such as silica having excellent light transmittance is particularly preferable.

【0036】

Conductive material In the inventions according to claims 1 to 3, a conductive substance is preferably used together with a photosemi-conductive substance. By adding a conductive substance, the photocatalytic performance can be further improved.

【0037】

As a method of adding the conductive substance, for example, in the manufacturing process of a photo-semi-conducting substance such as titanium oxide, the photo-semi-conducting substance is contained so that, for example, an iron oxide component as a conductive substance is contained in the structure. A method of incorporating a conductive substance as a part of, or Examples thereof include a method of chemically or physically supporting a conductive substance on the surface of a photosemi-conductive substance such as titanium oxide.

【0038】

As a simpler method, a method of adhering a mixture of a photosemi-conductive substance and a conductive substance to an uncured thin film, or a method of adhering a conductive substance before or after adhering the photo-semi-conducting substance is performed. Examples include a method of contacting with a photosemi-conductive substance.

【0039】

As the conductive substance used, carbon powder (fiber) and metal powder (fiber) generally used for imparting conductivity can be used. Examples include carbon black, silver, copper, gold, iron, aluminum, nickel, platinum, palladium, tin oxide, indium oxide and the like. Further, a non-conductor may be used as a core material, and the surface thereof may be coated with a conductor. Examples include silver-plated fine particles, aluminum-coated fine particles, barium sulfate fine particles whose surface is coated with tin oxide, and the like.

【0040】

Among the above conductive substances, from the practical point of view, tin oxide fine particles that are easily available and relatively inexpensive, and barium sulfate fine particles whose surface is coated with tin oxide are preferable. Tin oxide to which 0.1 to 20% by weight of antimony oxide is added is preferably used because it exhibits high conductivity.

【0041】

The amount of the conductive substance added to the photosemi-conductive substance is preferably 0.01 to 100 parts by weight with respect to 100 parts by weight of the photosemi-conductive substance, and the conductive substance may be contained in the photosemi-conductive substance. When added without going through a special step for contacting, such as supporting the substance on the surface, the amount is preferably 1 to 100 parts by weight. If it is less than the above range, the effect of adding the conductive substance is unlikely to occur. Further, even if the amount exceeds the above range, the effect is not further increased, but the photocatalytic effect is not impaired, and the addition amount may be increased when used as a carrier of a photosemi-conductive substance. ..

【0042】

Base material The base material used in the inventions according to claims 1 to 3 is not particularly limited as long as it can form a thin film by applying a solution for forming an uncured thin film. Examples of such a base material include inorganic materials such as glass and ceramics, organic materials such as plastics or wood, and metals. Further, the shape and size of the base material are not particularly limited.

【0043】

Details of manufacturing method Preparation of raw material solution for forming uncured thin film In the invention according to claim 1, when the molar ratio of each raw material in the raw material solution is shown as 1 for metal alkoxide, metal alkoxide: solvent: water = 10: 10 to 60: 2 to 8 is preferable. Further, in the invention according to claim 2, when the metal alkoxide is shown as 1 as described above, the metal alkoxide: solvent: complexing agent: water = 10: 10 to 60: 0.5 to 3: 2 to 8 is preferable. ..

【0044】

When the amount of the solvent is less than the above with respect to the metal alkoxide, the dissolution of the metal alkoxide may be insufficient, and it may be difficult to obtain a uniform thin film. On the contrary, if the amount of the solvent is larger than the above, it may be difficult to remove the solvent in a later step, or the drying step may take a long time. When the amount of water is less than the above range, the hydrolysis rate of the metal alkoxide may decrease, and further, in the invention according to claim 2, the reaction rate of hydrolysis of the complex formed by the metal alkoxide and the complexing agent. May decrease, or the reaction itself may be inadequate.

【0045】

On the contrary, when the amount of water is more than the above range, the water dispersion rate of the metal alkoxide may become too high, and further, in the invention according to claim 2, the reaction rate of the complex becomes too high, so that the base material is used. The handleability in the coating process and the physical properties of the thin film formed may be deteriorated. If the amount of the complexing agent is less than the above range, the formation of the complex between the metal alkoxide and the complex may be insufficient, and the thin film may not be formed. On the contrary, if the amount of the complexing agent is more than the above range, a large amount of impurities are mixed in the reaction system, so that the physical characteristics of the formed thin film may be deteriorated.

【0046】

The method for preparing the raw material solution can be carried out using a commercially available stirrer or homogenizer. Further, as in the invention of claim 2, when a complexing agent is used, a method for confirming the formation of a complex from a metal alkoxide and observing a change in the absorption spectrum in the ultraviolet region due to a chelate bond accompanying the formation of the complex. Can be used.

【0047】

Application of raw material solution to substrate The method of applying the raw material solution prepared as described above onto the substrate is not particularly limited. Examples of the coating method include spray coating, spin coating, dip coating, roll coating, curtain flow coating, meniscus coating and the like.

【0048】

However, it is preferable to select the above coating method according to the size and shape of the base material to be used, the desired coating site, the thickness of the coating, and the like. Further, in general, it is preferable to use spray coating or dip coating in consideration of workability, convenience of the apparatus, and the like.

【0049】

In carrying out the above coating method, it is necessary to apply the raw material solution before the viscosity increases due to gelation. The allowable viscosity range varies depending on the coating method and cannot be uniquely determined.

【0050】

Adhesion of photosemi-conductive substances In the present invention, after forming an uncured thin film on the substrate as described above, the photosemi-conductive substance is adhered onto the uncured thin film. The method of adhering the photosemi-conductive substance on the uncured thin film can be performed by any method such as spray coating, spin coating or transfer method. In the transfer method, a material having releasability, for example, a light semiconducting substance is attached to a polyethylene terephthalate film by an appropriate method such as fupre coating, and then the material having releasability is photo-half. This is a method of copying a photosemi-conducting substance onto an uncured thin film by bringing the surface to which the conductive substance is attached and an uncured thin film into close contact with each other by, for example, a press.

【0051】

The amount of the photosemi-conductive substance attached is not particularly limited as long as the required photocatalytic activity can be exhibited according to the purpose such as antibacterial, deodorizing, antifouling, and nitrogen oxide removal. However, in order to reduce the cost and prevent the photosemi-conductive substance from being detached from the film after photo-curing, it is preferable that the amount of the photo-semi-conductive substance used is small.

【0052】

Further, as described below, a conductive substance may be attached in order to improve the photocatalytic activity. Regarding the method of adhering the conductive substance on the uncured thin film for enhancing the photocatalytic activity, the photosemi-conductive substance and the conductive substance are mixed in advance using a commercially available stirrer or a homogenizer, and then the mixture is prepared as described above. After adhering the photosemi-conductive substance by the method of adhering it, and then performing photocuring, and forming an uncured thin film, the photosemi-conductive substance is adhered by the above-mentioned adhering method, and further conductive After forming an uncured thin film by a method of attaching a substance by spray coating, spin coating or transfer method, a conductive substance is attached onto the uncured thin film by spray coating, spin coating or transfer method, and then. Examples thereof include a method of adhering a photosemi-conductive substance according to the above adhering method. The amount of the conductive substance attached is as described above.

【0053】

Thin film drying The uncured thin film formed by the coating method described above is dried to remove the solvent. As the drying method, various commercially available dryers and heating furnaces can be used, or the drying method can be left at room temperature. However, it is preferable to use a dryer for the purpose of preventing dust from adhering to the film and shortening the drying time. In this case, in order to prevent local drying on the thin film, it is necessary to select a dryer according to the material and shape of the base material.

【0054】

Photocuring After the above drying, the thin film is irradiated with light to cure it. The light source in this case is not particularly limited, but for example, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, or the like can be used. When using these light sources, a filter or the like may be used to cut light having a wavelength unnecessary for curing.

【0055】

The irradiation conditions of light using the above light source cannot be unconditionally determined because they differ depending on the composition and thickness of the thin film, but it is desirable to determine them by, for example, the following method. In the invention according to claim 1, when the complexing agent is not used, the light absorption wavelength of the metal alkoxide in the ultraviolet light region is investigated. Next, it is desirable to irradiate with light having a wavelength at which the metal alkoxide is decomposed. The light irradiation time is determined by examining the change in the absorption spectrum at the absorption wavelength.

【0056】

On the other hand, when a complexing agent is used as in the invention of claim 2, the absorption spectra of the metal alkoxide alone and the complexing agent used in combination are compared, and the complex is formed by using the complexing agent. Determine the absorption maximum wavelength derived from the chelate bond. This absorption maximum wavelength is generally in the ultraviolet light region. Irradiate light near the absorption maximum wavelength and measure the change in the absorption spectrum near the absorption maximum wavelength. The wavelength of the irradiation light for photocuring shall be near the absorption maximum wavelength, and the irradiation time shall be determined from the observation result of. By each of the above-mentioned methods, suitable light irradiation conditions can be determined according to the type of metal alkoxide or complexing agent used in the reaction system.

【0057】

Combined use of heat in photocuring In the inventions according to claims 1 to 3, it is not necessary to carry out the firing step. However, heat may be applied to the substrate before and after photo-curing, or at the same time as photo-curing. Further, the raw material solution may be applied to the base material, dried, and then heat may be applied to the formed uncured thin film.

【0058】

When heating is used in combination as described above, the curing of the thin film is promoted, the curing time may be shortened, and the physical characteristics of the cured thin film, for example, the film strength may be improved. When heating is used in combination, the amount of heat applied is not particularly limited as long as the base material does not deteriorate or deform.

【0059】

As a device for heating, a normal heating furnace may be used. However, it is necessary to appropriately use different devices depending on each condition such as heat resistance and size of the base material and whether or not photocuring and heating are performed at the same time.

【0060】

Action In the invention according to claim 1, after forming an uncured thin film on a substrate, a photosemi-conductive substance is attached onto the uncured thin film, and then the thin film is irradiated with light according to a photocurable sol-gel method. Is cured. Therefore, since the thin film is cured without requiring a high-temperature firing step, a material having inferior heat resistance can be used as the material constituting the base material. That is, the material constituting the base material can be selected from a wide range of materials. In addition, since the photosemi-conductive substance is attached to the uncured thin film and then cured, the photo-semi-conductive substance is reliably exposed on the surface, and thus the photocatalytic activity can be more reliably expressed. ..

【0061】

In the invention according to claim 2, since the uncured thin film contains a complexing agent that shifts the light absorption wavelength, it can be shifted to the light absorption long wavelength side, whereby a light source or optics that can be used can be used. The selection range of the system or the selection range of the device other than the optical system can be expanded.

【0062】

In the invention according to claim 3, since titanium dioxide is used as the photosemi-conductive substance, the titanium dioxide is easily available and exhibits excellent photocatalytic activity, so that the thin film is inexpensive and has excellent photocatalytic performance. Can be provided.

【0063】

[Example]

Hereinafter, the present invention will be clarified by giving non-limiting examples of the present invention.

【0064】

(Example) 10 g of zirconium (IV) tetra n-butoxide, which is a metal alkoxide, was diluted with 80 ml of 1-propanol as a solvent and stirred to prepare a zirconium alkoxide solution. Next, 3 g of acetylacetone was added as a complexing agent, and the mixture was stirred at room temperature for about 1 hour to form a chelate with the metal alkoxide. To this, 2 ml of water was added, and the mixture was stirred for about 2 hours.

【0065】

The above solution was applied to a thickness of 1 μm by a spray coating method on the entire surface of one side of a transparent acrylic plate of 50 mm (width) × 50 mm (length) × 3 mm (thickness). Next, 0.2 g of anatase-type titanium oxide (primary particle size 0.3 μm, manufactured by Wako Pure Chemical Industries, Ltd.), which is a photosemi-conductive substance, was adhered by a spray coating method so as to be uniformly dispersed. After that, the solvent was volatilized to dry the thin film, and then the thin film was irradiated with light having a wavelength of 300 nm for 6 minutes to obtain a functional thin film sample.

【0066】

(Comparative example) Titanium oxide (anatase type, primary particle size 0.3 μm, manufactured by Wako Junyaku Co., Ltd.) 0.2 g in 2 g of one-component dry acrylic paint (Acrydic A-166, manufactured by Dainippon Ink and Chemicals Co., Ltd.) It was kneaded and 5 ml of toluene was added. This suspension was applied to the entire surface of one side of a transparent acrylic plate of 50 mm (width) × 50 mm (length) × 3 mm (thickness) by a spray coating method, and dried to prepare a sample.

【0067】

The samples obtained in the above Examples and Comparative Examples were evaluated for antibacterial and antifungal properties as antibacterial tests as follows. The results are shown in Table 1. In addition, the antibacterial property test was also performed on the sample after the weather resistance promotion test was performed. The results are shown in Table 2.

【0068】

Antibacterial evaluation method The samples prepared in Examples and Comparative Examples were placed in a sterilized petri dish, and the test bacterial solution [Heart Infusion Broth medium (hereinafter BHI medium, manufactured by DIFCO, 25 g / l) was diluted 100-fold with physiological saline. 1 x 10 test bacteria in the thing⁷Prepared to be CFU / ml] was dispensed by 1 ml each and covered. The petri dish was sealed and cultured at 30 ° C. for 1 day under fluorescent light, and then the viable cell count of the test bacteria after the culture was measured by a normal colony counting method.

【0069】

Antifungal evaluation method For molds and yeasts cultured on potato dextrose agar medium (hereinafter PDA medium, manufactured by Nissui Pharmaceutical Co., Ltd.) in advance, the cells were scraped off using a loop loop, placed in 0.05 wt% Tween80-added physiological saline, dispersed and stirred. Filtering was performed using a glass filter. The obtained filtrate was centrifuged at 10000 rpm for 15 minutes to remove the supernatant, and a precipitate (spore) was obtained. An appropriate amount of potato dextrose liquid medium (hereinafter referred to as PDB medium, manufactured by DIFCO) was added thereto to prepare a spore suspension.

【0070】

After autoclave sterilization, the PDA medium was incubated at 45 ° C so that the agar did not solidify, and 1/10 of the above spore suspension was added to this and stirred.

【0071】

The samples used in Examples and Comparative Examples were placed in a sterilized petri dish, and 50 μl of the above PDA medium containing a spore suspension was added dropwise thereto to solidify the sample into a hemisphere. The petri dish was sealed and cultured at 30 ° C for 3 to 5 days under fluorescent lighting, and then the growth of the fungus was visually determined. The judgment was made according to the following criteria. No growth of test bacteria × Growth of test bacteria is observed [0072]

Weatherability The antibacterial and antifungal properties of the sample after 100 hours of weather resistance promotion test using a test device using a sunshine carbon arc lamp specified in JIS-A1415 are as described above. evaluated.

【0073】

[table 1]

<img file="JPH10235203A_D0002.tif" />【0074】

[Table 2]

<img file="JPH10235203A_D0003.tif" />【0075】

Compared to the comparative example in which titanium oxide is simply dispersed in a thin film made of an acrylic paint, in the example in which a photosemi-conductive substance is supported on an inorganic thin film formed by the photocurable sol-gel method, antibacterial properties are obtained. Excellent results were shown in both the antifungal and antifungal properties. This is because, in the examples, it is unlikely that titanium oxide as a photosemi-conductive substance is embedded in the thin film, and it is exposed on the surface of the thin film in a considerable proportion, so that sufficient photocatalytic activity is exhibited. It is thought that it is because of it.

【0076】

[Effect of the invention]

As described above, in the invention according to claim 1, since the thin film is cured by the photocurable sol-gel method, a high-temperature firing step is not required. Therefore, a base material made of a synthetic resin having inferior heat resistance can be used, and the material of the base material can be selected from a wide range of materials. Further, since the thin film is cured after the photosemi-conductive substance is adhered onto the uncured thin film, the photosemi-conductive substance can be reliably exposed from the surface of the thin film. Therefore, a thin film having high photocatalytic activity can be easily provided. Further, since the surface coating is made of an inorganic substance, the weather resistance is improved as compared with the coating using a general synthetic resin.