Photocatalytic membrane having antistatic effect and photocatalytic coating for forming same

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a photocatalytic paint capable of forming a photocatalytic film having an antistatic effect, a method for forming a photocatalyst film using the paint, and a base material having the photocatalyst film. The photocatalytic coating material according to the present invention can form a photocatalytic film having excellent photocatalytic activity, film strength and transparency, and an antistatic effect on the surface of the base material, thereby providing the base material with antistatic antifouling property. It is possible to impart an environmental purification function such as antibacterial property due to photocatalytic activity.

【0002】

[Conventional technology]

It has been conventionally known that titanium oxide functions as a photocatalyst and causes decomposition and oxidation of substances when irradiated with light. Utilizing the photocatalytic action of titanium oxide, environmental purification (eg, deodorization, antifouling, antibacterial, etc.) is performed by removing trace amounts of harmful components existing in indoor and outdoor spaces, especially organic harmful components including microorganisms. Attempts have been made to prevent mold and the like. For example, it has become widely used to form a titanium oxide-based photocatalyst film on an inorganic base material such as glass and decompose organic substances adhering to or in contact with the base material.

【0003】

Such a photocatalytic film is required to have high film strength and high transparency in addition to the basic property of high photocatalytic activity. If the membrane strength is low, the durability of the photocatalytic membrane becomes insufficient, and the effect is not sustained. If the transparency is low, the appearance of the base material is spoiled and it cannot be applied to a transparent base material such as glass.

【0004】

In order to enhance the photocatalytic activity of titanium oxide, a potassium compound or a potassium compound + aluminum or a phosphorus compound is supported on the titanium oxide (Japanese Patent Laid-Open No. 8-182934), or phosphorus oxide is supported on the potassium compound (Japanese Patent Laid-Open No. 9-75748). Gazette) is known. However, the method of supporting such another compound does not lead to sufficient improvement in activity and is not a simple method.

【0005】

In addition, the photocatalyst exhibits organic matter resolution when irradiated with light, especially light containing ultraviolet rays, but does not act as a photocatalyst in an environment where ultraviolet rays do not exist, such as at night, and cannot exhibit environmental purification functions such as antibacterial properties. Therefore, a method of supporting an antibacterial metal such as silver on the surface of titanium oxide has been proposed (Japanese Patent Laid-Open No. 2-6333). As a result, it becomes a photocatalytic film that exerts an antibacterial effect even at night, but although this film contains silver, which is a good conductor, it has no conductivity and cannot be used for antistatic applications. Further, the transparency of the film is also very poor, and when the base material is transparent, the transparency of the base material is greatly impaired. So, for example, it is not very applicable to cathode ray tubes (CRTs).

【0006】

[Problems to be Solved by the Invention]

An object of the present invention is a photocatalytic coating film capable of forming a photocatalytic film having sufficient conductivity to impart antistatic properties and also having good photocatalytic activity and transparency, and a photocatalytic film using this coating material. It is to provide a film forming method and a photocatalytic film.

【0007】

[Means for solving problems]

As a result of intensive research to solve the above problems, the present inventors have made a dispersion in which titanium oxide carrying a metal is dispersed in an organic solvent containing β-diketone and a coupling agent, and an alkoxysilane. We have found that a transparent photocatalyst film exhibiting conductivity can be obtained by mixing with the hydrolyzed solution of the above to form a paint, and have reached the present invention.

【0008】

The photocatalytic coating material according to the present invention comprises (A) a dispersion in which titanium oxide carrying a metal is dispersed in an organic solvent containing β-diketone and a coupling agent, and (B) alkoxysilane at least partially. It is a two-component photocatalytic paint characterized by being composed of a solution of a hydrolyzate that has been hydrolyzed.

【0009】

In a preferred embodiment, -The metal carried on titanium oxide is one or more selected from the group consisting of gold, silver, platinum, palladium, ruthenium, rhodium, osmium, iridium and copper. The amount of metal supported is 5 to 20 wt% with respect to titanium oxide. Titanium oxide is an ultrafine titanium oxide with an average primary particle size of 0.1 μm or less. Coupling agents are selected from titanate-based and aluminum-based coupling agents. -The amount of β-diketone is 0.5 to 10.0 wt% of the metal-supported titanium oxide. -The amount of coupling agent is 0.1 to 5.0 wt% of the metal-supported titanium oxide. The content of metal-supported titanium oxide after mixing the two liquids is 0.5 to 20 wt%. -The weight ratio of (A) the amount of metal-supported titanium oxide in the liquid / (B) the silica-equivalent solid content in the liquid is in the range of 70/30 to 90/10, and / or -Solution (B) is formed by heating an alcohol solution of alkoxysilane in the presence of acid and water.

【0010】

According to the present invention, the titanium oxide dispersion liquid (A) of the above photocatalytic paint and the alkoxysilane hydrolyzate solution (B) are mixed, the obtained mixed liquid is applied to a base material, and the coating film is dried. Also provided is a method for forming a photocatalytic film, which comprises forming a photocatalytic film. It is preferable to dry the coating film by heating.

【0011】

Using the photocatalytic coating material of the present invention, a photocatalyst film can be formed on the surface of an inorganic base material, preferably a glass base material, and after forming an inorganic base layer on the surface of an organic base material, a photocatalyst film is formed. can do. The substrate may be, for example, a material selected from the group consisting of glass, plastic, metal, wood, ceramic, cement, concrete, fiber, paper and leather.

【0012】

BEST MODE FOR CARRYING OUT THE INVENTION

The photocatalytic paint of the present invention is a two-component paint composed of a dispersion liquid (A) in which titanium oxide, which is a photocatalyst, is dispersed in an organic solvent, and a binder solution (B). As the titanium oxide, ultrafine titanium oxide on which a metal is supported, preferably having an average primary particle diameter of 0.1 μm or less is used. In addition to this metal-supported titanium oxide, the titanium oxide dispersion (A) contains β-diketone and a coupling agent in an organic solvent, and the binder solution (B) is hydrolyzed at least partially hydrolyzed alkoxysilane. Use a solution of the decomposition product.

【0013】

When the solution of this alkoxysilane hydrolyzate and the dispersion liquid of ultrafine titanium oxide are mixed and stored, the liquid tends to gel during storage, so both must be stored separately. Therefore, the photocatalytic paint of the present invention is a two-component type, and these two solutions are mixed and used for coating before use.

【0014】

As the titanium oxide of the photocatalyst, it is preferable to use ultrafine particles having an average primary particle size of 0.1 μm or less. Titanium oxide having an average primary particle size larger than 0.1 μm has insufficient photocatalytic activity, especially when the content of titanium oxide in the photocatalytic film is relatively low. In addition, as pointed out in the prior art, the coating film becomes cloudy and the transparency is significantly reduced. The average primary particle size of titanium oxide is more preferably 0.01 to 0.1 μm, and particularly preferably 0.01 to 0.05 μm.

【0015】

The ultrafine titanium oxide may be produced by either a vapor phase method (eg, thermal hydrolysis of titanium tetrachloride) or a liquid phase method (eg, sulfuric acid method). .. Ultrafine titanium oxide produced from titanium tetrachloride gas is commercially available, for example, from Japan Aerosil Co., Ltd. under the trade name P-25, and this can be used as it is.

【0016】

There are two types of industrially used titanium oxide, anatase type and rutile type. Both can be used, but the anatase type is preferable because it has higher photocatalytic activity.

【0017】

In the present invention, a metal is supported on titanium oxide for use in order to impart conductivity to the photocatalyst film. The metal to be supported is preferably one having high electrical conductivity. Specifically, it is preferable to support one or more metals obtained from precious metals (that is, gold, silver, platinum, palladium, ruthenium, rhodium, osmium, iridium) and copper on titanium oxide.

【0018】

The metal can be supported on titanium oxide, for example, as follows. First, titanium oxide is dispersed in water to obtain an aqueous dispersion of titanium oxide. The concentration of titanium oxide at this time is preferably in the range of 1 to 10 wt%. A water-soluble salt of the supported metal is added to the obtained aqueous dispersion and dissolved in water. The amount of metal supported can be adjusted by the amount of this metal salt added. Alternatively, titanium oxide may be dispersed in an aqueous solution in which a water-soluble salt of the supported metal is dissolved in water. Next, the dispersion liquid of titanium oxide in the metal salt aqueous solution is irradiated with ultraviolet rays, and the metal salt in the solution is reduced to metal by the reducing power of titanium oxide. UV irradiation continues until the reduction is substantially complete. Then, the water is evaporated and removed, and the titanium oxide powder is dried to obtain titanium oxide on which a metal is supported.

【0019】

The amount of metal supported is preferably in the range of 5 to 20 wt% with respect to titanium oxide. If the amount of metal supported is less than 5 wt% with respect to titanium oxide, almost no conductivity (antistatic effect) can be obtained, and if it exceeds 20 wt%, the catalytic activity decreases. A more preferable amount of metal supported is in the range of 5 to 10 wt%.

【0020】

The organic solvent for dispersing the metal-supported titanium oxide is not particularly limited. Examples of solvents that can be used include alcohols such as methanol, ethanol, isopropanol and butanol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; hydrocarbons such as toluene, xylene, hexane and cyclohexane. The organic solvent may be used alone or in combination of two or more. Preferred solvents are alcohols. Alcohols also include alkoxy alcohols, that is, ether group-containing alcohols. Examples of this type of alcohol include 2-methoxyethanol and 1-methoxy-2-propanol.

【0021】

The β-diketone and the coupling agent improve the dispersibility of the metal-supported titanium oxide in the organic solvent, thereby improving the storage stability of the paint and increasing the transparency of the obtained coating film (reducing the haze). ) To add. These may be added in advance to the solvent before the metal-supported titanium oxide is dispersed, or may be added at the same time when the titanium oxide is dispersed in the solvent. Since these are one type of dispersion aid, it is not impossible, but not very preferable, to add them after the titanium oxide has been dispersed.

【0022】

Examples of β-diketone are 2,4-pentanedione (= acetylacetone), 3-methyl-2,4-pentanedione, 3-isopropyl-2,4-pentanedione, 2,2-dimethyl-3,5. -Hexanedione, 2,2,6,6-tetramethyl-3,5-heptanedione (= dipivaloylmethane), etc. can be mentioned, and one or more types can be used.

【0023】

If the amount of β-diketone added is less than 0.5 wt% with respect to the metal-supported titanium oxide, sufficient dispersibility cannot be obtained, while if it exceeds 10.0 wt%, it does not lead to further improvement in dispersibility. It is preferably in the range of wt%. A more preferable addition amount is 0.5 to 5.0 wt%.

【0024】

As the coupling agent, the most common silane coupling agent can be used, but it is preferable to use a titanate-based or aluminum-based coupling agent. Examples of coupling agents suitable for use in the present invention include aluminate-based coupling agents having an acetalkoxy group and titanate-based coupling agents having a dialkylpyrophosphate group or a dialkylphosphite group.

【0025】

An example of an aluminate-based coupling agent having an acetoalkoxy group is a compound represented by the following formula (a). Further, in the example of the titanate-based coupling agent having a dialkylpyrophosphate group, there are compounds represented by the following formulas (b) to (d), and in the example of the titanate-based coupling agent having a dialkylphosphite group, the following ( e) There are compounds represented by ~ (f). One or more of these can be used.

【0026】

[Chemical 1]

<img file="JPH11323192A_D0001.tif" />【0027】

If the amount of the coupling agent added is less than 0.1 wt% with respect to the metal-supported titanium oxide, the effect of reducing dispersibility and haze cannot be obtained, while if it exceeds 5.0 wt%, no further effect can be obtained. It is preferably in the range of ~ 5.0 wt%. A more preferable addition amount is 0.1 to 2.5 wt%.

【0028】

As the binder, a hydrolyzate obtained by at least partially hydrolyzing alkoxysilane is used, and as described above, a solution of this binder is prepared separately from the metal-supported titanium oxide dispersion.

【0029】

Akoksilan undergoes hydrolysis and polycondensation to form a polymer with a siloxane bond represented by -Si-O-, and finally forms a siliceous film when organic substances are completely removed. It is one kind. When alkoxysilane is used without hydrolysis, it takes a long time to form a film (drying of the coating film), and metal-supported titanium oxide tends to aggregate during drying, which hinders the transparency and homogeneity of the coating film. To.

【0030】

Hydrolysis of alkoxysilane can be carried out by heating an alcohol solution of alkoxysilane, preferably tetraalkoxysilane, in the presence of water and an acid, and by controlling the reaction at this time, the degree of hydrolysis can be controlled. Can be controlled. As the acid catalyst, an inorganic acid such as sulfuric acid, nitric acid or hydrochloric acid is preferable, but an organic strong acid such as paratoluenesulfonic acid can also be used. Hydrolysis is carried out so that a partial hydrolyzate (a part of the alkoxy group of the alkoxysilane remains) or a silica sol (a hydrolyzate containing substantially no alkoxy group) can be obtained. You may. The alcohol used as the solvent may be the same as that used in the titanium oxide dispersion.

【0031】

As the alkoxysilane, ethyl silicate (= tetraethoxysilane) is generally often used, but the present invention is not limited to this, and other alkoxysilanes, preferably tetraalkoxysilanes, can also be used. The alkoxysilane to be subjected to the partial hydrolysis reaction may be a monomer, or may be an oligomer of an alkoxysilane that has been lightly hydrolyzed in advance. The oligomer is preferably in the 2 to 100 mer, especially the 3 to 50 mer, on average.

【0032】

A preferred reaction solution for partial hydrolysis is a monomer or oligomer of alkoxysilane.₂In terms of conversion, it contains 5 to 20 wt%, 90 to 65 wt% of organic solvent, 0.05 to 0.5 wt% of catalytic acid, and 4.95 to 14.5 wt% of water. When this reaction solution is used, partial hydrolysis of the alkoxysilane is preferably carried out at a relatively low temperature of 30 to 60 ° C, particularly 35 to 55 ° C, for about 2 to 5 hours. Under this condition, a general partial hydrolyzate is obtained. However, the reaction conditions and the composition of the reaction solution are not particularly limited as long as a solution of the hydrolyzate of alkoxysilane is obtained.

【0033】

The reaction solution obtained after hydrolysis is used as it is or, if necessary, the concentration is adjusted and used as the binder solution (B) of the present invention. The acid catalyst and water used for hydrolysis may remain in this solution.

【0034】

The photocatalytic coating material according to the present invention can be produced by mixing the above-mentioned dispersion liquid (A) of metal-supported titanium oxide and a binder solution (B) containing an alkoxysilane hydrolyzate.

【0035】

The content of the metal-supported titanium oxide in the photocatalytic paint produced by mixing the two liquids in this way is preferably in the range of 0.5 to 20 wt%. If the content of the metal-supported titanium oxide is less than 0.5 wt%, the film thickness at the time of film formation becomes thin, and if it is desired to increase the film thickness, it is troublesome to recoat several times. When the content of the metal-supported titanium oxide exceeds 20 wt%, the dispersibility of titanium oxide tends to decrease, and the transparency of the photocatalyst film tends to decrease. A more preferable content of metal-supported titanium oxide is 0.5 to 10 wt%.

【0036】

Regarding the ratio of metal-supported titanium oxide to binder, which is a photocatalyst, the weight ratio of the amount of metal-supported titanium oxide in the titanium oxide dispersion (A) / the silica-equivalent solid content in the binder solution (B) is 70 /. It is preferably in the range of 30 to 90/10. If this weight ratio is less than 70/30, the photocatalytic activity and conductivity will decrease, and if it is greater than 90/10, the amount of binder will be too small and the film strength will be insufficient.

【0037】

When the photocatalytic paint of the present invention is applied to a base material and the coating film is dried, a conductive photocatalyst film is formed on the surface of the base material. The coating method is not particularly limited, and examples thereof include spin coating, roll coating, spray coating, bar coating, and dipping, and may be selected according to the type and shape of the base material.

【0038】

Although the coating film can be dried at room temperature, it is preferable to heat-dry it in order to shorten the drying time. The heating temperature is generally preferably in the range of 50 to 170 ° C, and is preferably equal to or higher than the boiling point of the organic solvent used in the coating material. In addition, the heating temperature must, of course, be lower than the heat resistant temperature of the base material. Therefore, the type of organic solvent is selected in consideration of the heat resistance of the base material.

【0039】

The film thickness of the photocatalyst film is not particularly limited, but is usually in the range of 0.1 to 1 μm. This photocatalytic film exhibits the excellent photocatalytic activity of titanium oxide, and at the same time, it has excellent adhesion to the substrate and high film strength (that is, high hardness and scratch resistance), so that it has excellent durability and long-term use. The photocatalytic activity can be exhibited. Moreover, since it is excellent in transparency, the transparency or appearance of the base material is not impaired. Further, by using titanium oxide on which a metal is supported, the photocatalyst film exhibits a certain degree of conductivity, and the photocatalyst film has an antistatic effect.

【0040】

This photocatalytic film exhibits conductivity in addition to high photocatalytic activity and transparency because the metal-supported titanium oxide particles form some kind of network in an appropriate aggregated form due to the addition of β-diketone and a coupling agent. Conceivable. In addition, it is considered that the action of the siliceous binder has high adhesion and film strength, and this binder contributes to the improvement of the adhesion between the titanium oxide particles and between the particles / base material, and forms a high-hardness film. It is thought to form.

【0041】

The base material to which the photocatalytic paint of the present invention is applied is not particularly limited, and may be organic or inorganic. Examples of substrate materials include glass, plastic, metal, wood, ceramics including tiles, cement, concrete, fibers, paper and leather.

【0042】

However, when a photocatalytic paint is applied to an organic base material such as plastic, the photocatalytic film formed on the base material may exert a photocatalytic action on the base material and decompose or deteriorate the base material. When applied to an organic base material, it is preferable to form a base layer for protecting the base material in advance and to form a photocatalyst film on the base layer. As the base layer, an inorganic film that is not deteriorated by the photocatalytic film is preferable.

【0043】

The preferred underlayer is siliceous. For example, the binder solution (B) of the two-component paint according to the present invention, that is, a solution of at least a partial hydrolyzate of alkoxysilane can be used alone to form an underlayer. Since the binder of the photocatalyst film is silica, if the base layer is also silica, the adhesion between the base layer and the photocatalyst film is particularly good, and the transparency is hardly impaired.

【0044】

When the base material is inorganic, the base layer is not required because the photocatalyst film does not deteriorate the base material, and the photocatalyst paint may be applied directly to the base material.

【0045】

The photocatalytic film formed on the surface of the substrate from the photocatalytic coating material according to the present invention exerts a catalytic action when irradiated with light, particularly light containing ultraviolet rays, and can decompose organic substances adhering to or in contact with the film. In this way, the base material is imparted with antibacterial and antifungal properties. It is also possible to detoxify oxidizable inorganic substances by oxidation (eg NO)._xAnd SO_xOxidation). Furthermore, since this photocatalytic film is conductive, it can also impart antistatic ability to the substrate and prevent dust from adhering to the substrate (imparting antifouling property).

【0046】

If the base material is transparent, light irradiation can be performed from the back side of the base material (the side on which the photocatalyst film is not formed). For example, if a photocatalytic film is formed on the indoor surface of the window glass, the photocatalytic action is exhibited by sunlight during the day and by the indoor illumination light at night, and it is generated from harmful organic substances in the room (eg, from building materials). It can decompose aldehydes, tobacco tar, oil generated in cooking, microorganisms such as bacteria and mold). In addition, the antistatic ability of the photocatalyst film can prevent the base material from becoming dirty.

【0047】

Specific examples of the base material suitable for forming the photocatalyst film of the present invention include vehicle and road mirrors, vehicle glass, vehicle illumination lamps and their covers, lenses, fluorescent lamps for illumination and their covers, and flat glass (windows). Glass, furniture glass, forehead glass, greenhouse glass, etc.), tunnel interior materials and lighting and their covers, plastic films and sheets, plastic moldings, various building / interior materials and building accessories (metal) , Ceramic, concrete, cement, wooden, natural stone and other natural or synthetic mineral or resin building materials, tiles, glass blocks, flooring, ceiling materials, wallpaper, doors, obstacles, Fusuma, net doors, sledges, tatami mats. , Blinds, sunshades or rain shelters, corrugated sheets, etc.), tableware, ventilators, glasses, mirrors, natural and synthetic fibers and fabrics, paper, leather products, brown tubes, cover glass, goggles, helmet shields, signs, signs , Metal plates, housings for home appliances, sintered metal filters, guard rails, vinyl houses, cooking ranges and their hoods, sinks, sanitary appliances (washbasins, toilets, pipes, etc.), bathtubs, furniture (cupboards and other cupboards, tables) , Desks, etc.), Fixing materials for outdoor lighting, Indoor or outdoor exhibits (eg, sculptures) and displays (eg, information boards), Outdoor furniture and play equipment (eg, benches, slides), Outdoor fixed structures (eg, slides) Examples, tombstones, electric poles), etc. are exemplified. However, the base material is not limited to this. These base materials can form the photocatalytic film of the present invention in either the state of the material before commercialization or after commercialization.

【0048】

For example, in a tunnel, by forming the photocatalytic film of the present invention on the surface of a tunnel illumination lamp and its cover, a tile for tunnel interior, or a metal plate, NO is added to the organic components in the exhaust gas._xAnd SO_xCan also be decomposed, which helps to purify the air in the tunnel. Other base materials can also decompose organic substances around them, and in addition to purifying the environment, they are also effective in antibacterial and antifungal properties of the base material.

【0049】

One example of a substrate to which the photocatalytic paint of the present invention is particularly preferably applied is a cathode ray tube (CRT) such as a television or computer. Since the cathode ray tube is prone to dust adhesion, forming a photocatalyst film on the surface according to the present invention imparts antifouling property and antibacterial antifungal property, and makes it difficult to get dirty.

【0050】

[Example]

(Example 1) Metal-supported titanium oxide was prepared by the following method. First, anatase-type ultrafine titanium oxide powder (P-25 manufactured by Nippon Aerosil Co., Ltd., average primary particle size 0.02 μm) produced by the vapor phase method was dispersed in pure water to prepare a 2 wt% aqueous dispersion. Silver nitrate is added to this dispersion in an amount so as to support a predetermined metal (silver) with respect to titanium oxide, dissolved in water, and then ultraviolet rays (1.2 mW / cm).²) Was irradiated for 5 hours. Then, the dispersion was heated to 100 ° C. to evaporate the water, and the powder was dried to obtain titanium oxide supporting silver. Other metals can be supported in the same manner.

【0051】

Add the silver-supported titanium oxide prepared above to a solution consisting of the alcohol-based organic solvent of the type and amount shown in Table 1, β-diketone, and titanate-based or aluminum-based coupling agent, and use 100 g of zirconia beads. The mixture was dispersed in a paint shaker for 16 hours to obtain a dispersion of silver-supported titanium oxide.

【0052】

Separately, by adding 400 g of ethanol, 45 g of water and 0.6 g of 60% nitric acid to 150 g of a 40 wt% ethanol solution of ethyl silicate, and heating at 45 ° C for 3 hours to hydrolyze the ethyl silicate, substantially organic substances are obtained. A removed silica sol was obtained. The silica equivalent concentration of this silica sol was 10 wt%.

【0053】

This 10% silica sol solution was mixed with the silver-supported titanium oxide dispersion prepared above in the amounts shown in Table 1 to prepare a photocatalytic paint. In Table 1, TiO₂/ SiO₂The weight ratio is the photocatalytic powder (TiO) with respect to the silica-equivalent solid content in the silica sol solution.₂) Is the weight ratio.

【0054】

This paint was applied to a glass substrate with a spin coater and dried at 150 ° C. for 1 hour to form a photocatalytic film. The film thickness of the formed photocatalyst film was in the range of 0.3 to 0.5 μm. The haze of the obtained photocatalyst film (Haze computer HGM-3D manufactured by Suga Test Instruments Co., Ltd.) and surface resistance (surface resistance meter Hiresta HT-210 manufactured by Mitsubishi Chemical Corporation) were measured.

【0055】

In addition, a glass plate (10 x 10 cm) having this photocatalytic membrane is placed in a 1-liter Pyrex container with the coating surface facing up, the container is sealed, and then a predetermined amount (350 ppm) of acetaldehyde is injected. , UV lamp (1.2 mW / cm) installed at a distance of 10 cm above this container²The photocatalytic activity was evaluated by measuring the acetaldehyde concentration after light irradiation for 2 hours with) with a gas tech detector tube and calculating the acetaldehyde removal rate by the following formula.

【0056】

Removal rate (%) = [(Initial concentration-Concentration after light irradiation) / Initial concentration] × 100 The results of these tests are also shown in Table 1. For comparison, a photocatalytic paint using titanium oxide before supporting silver and a metal-supported titanium oxide were used, but a photocatalytic paint omitting β-diketone or a coupling agent was also prepared in the same manner for film formation. Used and tested. The results of these tests are also shown in Table 1.

【0057】

[table 1]

<img file="JPH11323192A_D0002.tif" />【0058】

As can be seen from Table 1, according to the present invention, the photocatalytic activity (organic matter removal rate) is as high as 75% or more, and the surface resistance is 10.⁸~10¹⁰It was possible to form a photocatalyst film with excellent transparency with a haze of 1.0 or less, which had sufficient conductivity to impart antistatic ability on the order of Ω / .

【0059】

On the other hand, in Comparative Examples 1 and 2 in which the titanium oxide dispersion liquid does not contain β-diketone or a coupling agent, metal-supported titanium oxide is used and metal-supported TiO.₂/ SiO₂The surface resistance of the photocatalytic membrane is unmeasurable (&gt; 10) despite the high weight ratio of 90/10.¹³), And no conductivity was observed in the film. In addition, a significant decrease in haze and a decrease in photocatalytic activity were also observed. Further, in Comparative Example 3 in which titanium oxide did not support a metal, the haze and the removal rate of organic substances were good, but of course no conductivity was observed in the photocatalyst film.

【0060】

In order to demonstrate the effectiveness of the photocatalytic paint of the present invention on various base materials, the photocatalytic paint of Example 1 in Table 1 was used, and the coating method and the base material were changed as shown in Table 2 to change the base material surface. A photocatalytic film was formed on the surface. When the base material is organic, the above binder solution (silica sol) is first applied by the same coating method, and the coating film is heated and dried to form a siliceous base protective layer, and a photocatalyst film is placed on the base protective layer. Formed. The coating film was dried by heating at 80 ° C. for 1 hour after application. The base material is cut out to about 10 x 10 cm, excluding the spectacle lens and the fluorescent lamp. The photocatalytic activity of the base material on which the photocatalytic film was formed in this way was evaluated by the above-mentioned organic matter removal rate. The test results are shown in Table 2 together with the film thickness.

【0061】

[Table 2]

<img file="JPH11323192A_D0003.tif" />【0062】

As can be seen from Table 2, the photocatalytic activity of the photocatalytic film was substantially the same as that of Example 1 even if the substrate and the coating method were different. Therefore, according to the present invention, it can be seen that a photocatalytic film having high photocatalytic activity can be formed on various base materials by a coating method suitable for the shape and material of the base material. When the base material was a material other than metal, the surface resistance was also measured, but all were at the same level as in Example 1.

【0063】

[Effect of the invention]

According to the present invention, it is possible to obtain a photocatalytic coating material which exhibits excellent photocatalytic activity and high transparency and can form a photocatalytic film having a sufficient level of conductivity for antistatic properties. Therefore, by utilizing the photocatalytic paint of the present invention, it is possible to impart antibacterial antifungal properties and antistatic properties to various base materials without impairing their transparency or aesthetics, and the use of photocatalysts can be used. Can be expanded.