Hydrophilic member, method for delivering hydrophilicity to the member, and surface forming composition for performing hydrophilicity

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention, in a broad sense, relates to a technique for making the surface of a substrate highly hydrophilic and maintaining it. More specifically, the present invention relates to an antifogging technique for preventing fogging and formation of water droplets on a base material by highly hydrophilicizing the surface of a mirror, lens, flat glass or other transparent base material. The present invention also provides a technique for preventing the surface from becoming dirty by making the surface of a building, window glass, mechanical device or article highly hydrophilic, or for self-cleaning or easily cleaning the surface. Regarding.

【0002】

[Problems to be Solved by Conventional Techniques and Inventions]

It is often experienced that the windshields and windows of automobiles and other vehicles, the windows of buildings, the lenses of eyeglasses, and the cover glass of various instrument panels become cloudy with condensed moisture in cold weather. In addition, it is often encountered that the lenses of mirrors and eyeglasses in bathrooms and washrooms become cloudy due to steam. The surface of the article becomes cloudy because when the surface is placed at a temperature below the dew point of the atmosphere, the moisture in the atmosphere condenses and condenses on the surface. If the condensed water droplets are sufficiently fine and their diameter is about half the wavelength of visible light, the water droplets scatter the light, the glass or mirror becomes apparently opaque, and visibility is lost. As the condensation of the wet matter progresses further and the fine condensed water droplets fuse with each other to grow into larger discrete water droplets, the surface becomes blunt due to the refraction of light at the interface between the water droplet and the surface and the interface between the water droplet and the air. Blurred, mottled, or cloudy. As a result, the perspective image is distorted and the transparency is lowered in a transparent article such as glass, and the reflected image is disturbed in a mirror. In addition, vehicle windshields and windows, building windows, vehicle rearview mirrors, eyeglass lenses, masks and helmet shields are exposed to rainfall and splashes, and a large number of scattered water droplets adhere to their surfaces. Is dull, blurry, mottled, or cloudy, and also loses visibility. The term "anti-fog" as used herein and in the appended claims broadly means a technique for preventing such optical damage due to fogging, growth of condensed water droplets, or adhesion of water droplets.

【0003】

Needless to say, anti-fog technology has a profound effect on safety and efficiency of various tasks. For example, if the windshield, window glass, or rear-view mirror of a vehicle becomes cloudy or holds, the safety of the vehicle or traffic is impaired. Fogging of endoscopic lenses and dental dentistry interferes with accurate diagnosis, surgery, and treatment. If the cover glass of the instrument panel becomes cloudy, it will be difficult to read the data. Wipers, defrosting devices and heaters are generally incorporated into the windshield of automobiles and other vehicles to ensure visibility in cold weather and rainy weather. However, it is not commercially feasible to attach these devices to the side windowpanes of automobiles or rear-view mirrors located outside the automobile. It is also possible, if not impossible, to attach these anti-fog devices to building windowpanes, eyeglass lenses, endoscopic lenses and dental dentistry, goggles, masks or helmet shields, and instrument panel coverpanes. Have difficulty.

【0004】

As is well known, a conventional simple anti-fog method is to apply an anti-fog composition containing a hydrophilic compound such as polyethylene glycol or a water-repellent compound such as silicone to the surface. However, this type of anti-fog film is only temporary and has the disadvantage that it is easily removed by washing with water or contact and loses its effect at an early stage. In Jitsukaihei 3-129357 (Mitsubishi Rayon), a polymer layer is provided on the surface of the base material, and this layer is irradiated with ultraviolet rays and then treated with an alkaline aqueous solution to generate high-density acidic groups, which produces a polymer. A method for preventing fogging of a mirror, which comprises making the surface of the layer hydrophilic, is disclosed. However, even in this method, it is considered that the surface loses its hydrophilicity over time due to the contaminants adhering to the surface, and the antifogging performance is gradually lost. Jitsukaihei No. 5-68006 (Stanley Electric) discloses an antifogging film composed of a graft polymer of an acrylic monomer having a hydrophilic group and a monomer having a hydrophobic group. The contact angle of this graft polymer with water is 50. It is considered that this antifogging film does not have sufficient antifogging performance. "Anti-fog coating technology for glass" by Isao Kaetsu (Latest coating technology, p. 237-249, published by General Technology Center, 1986) describes various anti-fog technologies of the conventional technology. However, the author, Kaetsu, said that the anti-fog technology by making the surface hydrophilic also has a big problem to be overcome in practical use, and the current anti-fog coating technology is considered to hit one wall. It is.

【0005】

Therefore, it is an object of the present invention to provide an antifogging method capable of achieving a high degree of visibility of mirrors, lenses, glass and other transparent substrates. Another object of the present invention is to provide an antifogging method capable of maintaining the surface of a mirror, a lens, glass, or other transparent substrate with a high degree of hydrophilicity for a long period of time. Yet another object of the present invention is to provide an antifogging method capable of keeping the surface of a mirror, lens, glass or other transparent substrate almost permanently highly hydrophilic. Another object of the present invention is to provide an antifogging coating having excellent durability and abrasion resistance. Another object of the present invention is to provide an anti-fog coating that can be easily adhered to a surface that requires anti-fog. Another object of the present invention is an anti-fog mirror, lens, glass, other transparent substrate, and a transparent base material capable of maintaining a highly hydrophilic surface for a long period of time and maintaining a high degree of anti-fog performance. It is to provide the manufacturing method.

【0006】

On the other hand, in the field of construction and painting, pollution of building exterior materials, outdoor buildings and their coating films has become a problem due to environmental pollution. Dust and particles floating in the atmosphere accumulate on the roof and outer walls of buildings in fine weather. Sediment is washed away by rainwater as it rains, and flows down the outer wall of the building. Furthermore, in rainy weather, floating dust is carried by the rain and flows down the outer walls of buildings and the surface of outdoor buildings. As a result, contaminants adhere to the surface along the rainwater path. When the surface dries, striped stains appear on the surface. Dirt on building exterior materials and coatings consists of combustion products such as carbon black and pollutants of inorganic substances such as urban dust and clay particles. It is believed that such diversity of pollutants complicates antifouling measures (Yoshinori Tachibana, "Test Method for Accelerating Contamination of Exterior Wall Finishing Materials," Architectural Institute of Japan, Structural Papers, No. 404. Issue, October 1989, p. 15-24). Conventional wisdom has been that water-repellent paints such as polytetrafluoroethylene (PTFE) are preferable to prevent stains on building exteriors, but recently, urban dust containing a large amount of lipophilic components. It is considered desirable to make the surface of the coating film as hydrophilic as possible (Polymer, Vol. 44, May 1995, p. 307). Therefore, it has been proposed to paint buildings with hydrophilic graft polymers (Newspaper "The Chemical Daily", January 30, 1995). According to reports, this coating film exhibits hydrophilicity with a contact angle of 30 to 40 ° with water. However, the contact angle of inorganic dust represented by clay minerals with water is 20 to 50 °, and it has an affinity for graft polymers with a contact angle of 30 to 40 ° with water and adheres to the surface. It is considered that the coating film of this graft polymer cannot prevent stains due to inorganic dust because it is easy to do. In addition, conventionally, acrylic resin, acrylic silicon resin, aqueous silicone, block polymer of silicone resin and acrylic resin, acrylic styrene resin, sorbitan fatty acid ethylene oxide, sorbitan fatty acid ester, urethane-based acetate, polycarbonate diol and / or poly Various hydrophilic paints made of crosslinked urethane of isocyanate and crosslinked polyacrylic acid alkyl ester are commercially available. The contact angle of these hydrophilic paints with water is at most 50 to 70 °, and it is not possible to effectively prevent stains caused by urban dust containing a large amount of lipophilic components.

【0007】

Therefore, another object of the present invention is to provide a method of making the surface of a substrate highly hydrophilic. Another object of the present invention is to prevent the surface from becoming dirty by making the surface of a building, a window glass, a mechanical device, or an article highly hydrophilic, or to self-clean or easily clean the surface. Is to provide a way to do it. Another object of the present invention is to provide a highly hydrophilic antifouling substrate and a method for producing the same, which can prevent the surface from becoming dirty, or can self-clean or easily clean the surface. is there. In some devices, the growth of moisture-condensed water adhering to the surface into water droplets impedes its function. For example, in a heat exchanger, when the water droplets adhering to the heat radiation fins grow into large water droplets, the heat exchange efficiency decreases. Therefore, another object of the present invention is to provide a method for forming a water film of the adhering moist condensed water by making the surface highly hydrophilic to prevent the adhering moist condensed water from growing into large water droplets. It is to be. Another object of the present invention is to provide a surface-forming composition that makes the surface of a substrate highly hydrophilic.

【0008】

[Means for solving problems]

The present inventor has discovered for the first time in the world that when a photocatalyst is photoexcited, the surface of the photocatalyst becomes highly hydrophilic. Surprisingly, when photocatalytic titania is photoexcited with ultraviolet light, the surface becomes highly hydrophilic so that the contact angle with water is 10 ° or less, more specifically 5 ° or less, especially about 0 °. Was discovered. The present invention is based on such a new discovery, and in a broad sense, the present invention describes a method for making the surface of a base material highly hydrophilic, a base material having a highly hydrophilic surface, and a method for producing the same. provide. According to the present invention, the surface of the substrate is coated with a wear resistant photocatalytic coating made of a photocatalytic semiconductor material. When light having a wavelength higher than the bandgap energy of the photocatalytic semiconductor is irradiated with sufficient illuminance for a sufficient time, the surface of the photocatalytic coating becomes superhydrophilic. The terms "superhydrophilicity" or "superhydrophilicity" used here are about 10 ° or less, preferably about 5 in terms of contact angle with water. It means a high degree of hydrophilicity (that is, water wettability) below . Similarly, the term superhydrophilification or superhydrophilification refers to a surface at an altitude of about 10 ° or less, preferably about 5 ° or less, in terms of contact angle with water. It means to make it hydrophilic.

【0009】

At present, the superhydrophilicization phenomenon of the surface caused by photoexcitation of a photocatalyst cannot always be clearly explained. The photocatalytic hyperhydrophilization phenomenon does not appear to be necessarily the same as the photocatalytic photodecomposition of substances by photocatalytic redox reactions conventionally known in the field of photocatalysts. In this regard, the conventional theory regarding photocatalytic redox reactions is that electron-hole pairs are generated by photoexcitation, and the generated electrons reduce surface oxygen to superoxide ions (O).^2-), The holes oxidize the surface hydroxyl groups to generate hydroxyl radicals ( OH), and these highly reactive reactive oxygen species (O)^2-Ya OH ) Was decomposed by the redox reaction. However, the photocatalytic hyperhydrophilization phenomenon is inconsistent with conventional findings regarding photocatalytic degradation of materials in at least two respects. First, according to the conventional wisdom, photocatalysts such as rutile and tin oxide do not have a sufficiently high energy level in the conductor, so that the reduction reaction does not proceed, and as a result, electrons photoexcited in the conductor are generated. It was thought that it became excessive and the electron-hole pairs generated by photoexcitation recombine without participating in the redox reaction. On the other hand, it was confirmed that the photocatalytic superhydrophilicization phenomenon also occurs in photocatalysts such as rutile and tin oxide, as will be described later. Secondly, conventionally, it is considered that decomposition of a substance by a photocatalytic redox reaction does not occur unless the film thickness of the photocatalytic layer is at least 100 nm or more. On the other hand, it was observed that photocatalytic superhydrophilization occurs even when the film thickness of the photocatalytic coating is on the order of several nm. Therefore, although it cannot be clearly concluded, the photocatalytic superhydrophilicization phenomenon is considered to be a phenomenon slightly different from the photocatalytic redox reaction of substances. However, as will be described later, it has been confirmed that superhydrophilicization of the surface does not occur unless light with an energy higher than the bandgap energy of the photocatalyst is irradiated. Probably due to the photocatalytic action of the photocatalyst, water is hydroxyl (OH) on the surface of the photocatalytic coating.^-It is considered that the surface becomes superhydrophilic by being chemically adsorbed in the form of).

【0010】

Once the surface of the photocatalytic coating is highly hydrophilic by photoexcitation, the surface hydrophilicity persists for some time even when the substrate is held in the dark. When pollutants are adsorbed on the surface hydroxyl groups with the passage of time and the surface gradually loses its superhydrophilicity, the superhydrophilicity is restored by photoexcitation again. For the first hyperhydrophilization of the photocatalytic coating, any light source with a wavelength of energy higher than the bandgap energy of the photocatalyst can be utilized. In the case of a photocatalyst whose photoexcitation wavelength is located in the ultraviolet region such as titania, the ultraviolet rays contained in the sunlight can be preferably used under the condition that the substrate coated with the photocatalytic coating is exposed to sunlight. it can. The photocatalyst can be photoexcited indoors or at night by an artificial light source. As will be described later, when the photocatalytic coating is made of silica-blended titania, it can be easily hydrophilized even with weak ultraviolet rays contained in a fluorescent lamp. Once the surface of the photocatalytic coating is superhydrophilic, it can be maintained or restored to superhydrophilicity by relatively weak light. For example, in the case of titania, the maintenance and restoration of superhydrophilicity can be sufficiently performed even with weak ultraviolet rays contained in indoor lighting such as fluorescent lamps.

【0011】

The photocatalytic coating exhibits superhydrophilicity even if it is very thin, and in particular, the photocatalytic semiconductor material made of a metal oxide has sufficient hardness, so that the photocatalytic coating has sufficient durability and abrasion resistance.

【0012】

The superhydrophilicization of the surface can be applied to various applications. From one aspect of the present invention, the present invention provides an antifogging method for a transparent member, an antifogging transparent member, and a method for producing the same. According to the present invention, a transparent member coated with a photocatalytic coating in advance is prepared, or the surface of the transparent member is coated with a photocatalytic coating. Transparent members include vehicle back mirrors, bathroom or washroom mirrors, dental dentistry mirrors, road mirror-like mirrors; eyeglass lenses, optical lenses, camera lenses, endoscopic lenses, lighting lenses-like lenses. Prism; Window glass of buildings and surveillance towers; Window glass of vehicles such as automobiles, railroad vehicles, aircraft, ships, submersibles, snow vehicles, ropeway gondola, amusement park gondola, spacecraft; automobiles, railroad vehicles, Windshield for vehicles such as aircraft, ships, submersibles, snow vehicles, snowmobiles, motorcycles, ropeway gondola, amusement park gondola, spacecraft; protective or sports goggles or masks (including diving masks) Shields; Mirror shields; Frozen food display case glass; Includes measuring instrument cover glass. By irradiating a transparent member with a photocatalytic coating with light and photoexciting the photocatalyst, the surface of the photocatalytic coating is made superhydrophilic. Since a uniform water film is formed without forming water droplets, no light-scattering fogging occurs on the surface. Similarly, even if the window glass, vehicle rear-view mirror, vehicle windshield, eyeglass lens, or helmet shield is exposed to rainfall or splashes, the water droplets adhering to the surface quickly spread over a uniform water film, so they are scattered. No unsightly water droplets are formed. Therefore, a high degree of visibility and visibility can be ensured, the safety of vehicles and traffic can be guaranteed, and the efficiency of various tasks and activities can be improved.

【0013】

In another aspect of the present invention, the present invention comprises a method of self-cleaning the surface of a base material by rainfall by making the surface of the base material superhydrophilic, a self-cleaning base material, and a self-cleaning base material. The manufacturing method is provided. Substrates are, for example, metal, ceramics, glass, plastics, wood, stone, cement, concrete, combinations thereof, laminates thereof, or building exteriors, window frames, structural members made of other materials. Window glass; exterior and painting of vehicles such as automobiles, rolling stock, aircraft and ships; exterior and painting of machinery and articles; dustproof covers and painting; including traffic signs, various display devices, exterior and painting of advertising towers. The surface of the substrate is coated with a photocatalytic coating. Mechanical devices and articles placed in buildings and outdoors are exposed to sunlight during the day, so the surface of the photocatalytic coating is highly hydrophilic. In addition, the surface is exposed to occasional rainfall. Every time the ultra-hydrophilic surface receives rainfall, soot and contaminants adhering to the surface of the substrate are washed away by raindrops and the surface is self-cleaned. The surface of the photocatalytic coating has a contact angle with water of 10 ° or less, preferably 5 ° or less, especially about 0. Since it is highly hydrophilic to the extent that it becomes more hydrophilic, not only urban soot containing a large amount of lipophilic components but also inorganic dust such as clay minerals can be easily washed away from the surface. In this way, the surface of the substrate is highly self-cleaned and kept clean by natural action. For example, the glass-wiping work of high-rise buildings can be eliminated or significantly eliminated.

【0014】

In still another aspect of the present invention, the present invention is a method of providing a photocatalytic coating on the surface of a building, window glass, mechanical device or article to make the surface highly hydrophilic to prevent the surface from becoming dirty. I will provide a. The hyperhydrophilic surface prevents contaminants from adhering to the surface when rainwater, which is accompanied by contaminants such as soot and dust floating in the atmosphere, flows down. Therefore, in combination with the self-cleaning effect of rainfall described above, the surface of buildings and the like is maintained highly clean almost permanently. [0015]

In another aspect of the invention, a device or article formed of metal, ceramics, glass, plastics, wood, stone, cement, concrete, combinations thereof, or laminates thereof (eg, building exteriors, buildings). The surface of interior materials, windowpanes, housing equipment, toilets, tubs, washbasins, lighting fixtures, kitchen utensils, tableware, sinks, cooking ranges, kitchen hoods, ventilation fans) is coated with a photocatalytic coating and photoexcited as needed. To. When these oil- or fat-stained articles are soaked in water, wetted with water, or rinsed with water, the oil stains are released from the surface of the superhydrophilic photocatalytic coating and easily removed. For example, dishes contaminated with oil or fat can be washed without the use of detergent.

【0016】

In another aspect of the invention, the invention provides a method of preventing the growth of water droplets adhering to a substrate or spreading the adhering water droplets over a uniform water film. Therefore, the surface of the base material is coated with a photocatalytic coating. When the photocatalytic coating is photoexcited to make the surface superhydrophilic, the moist condensed water or water droplets adhering to the surface of the base material spreads on the surface to form a uniform water film. When this method is applied to, for example, the heat radiation fins of a heat exchanger, it is possible to prevent the passage of the heat exchange medium from being clogged by condensed water and increase the heat exchange efficiency. Alternatively, applying this method to mirrors, lenses, windowpanes, windshields, and pavements can accelerate the drying of the surface after wetting. The above features and effects of the present invention, as well as other features and effects, will become apparent as described in the examples below.

【0017】

BEST MODE FOR CARRYING OUT THE INVENTION

A substrate that requires superhydrophilization of the surface is prepared and coated with a photocatalytic coating. When the base material is made of a heat-resistant material such as metal, ceramics, or glass, the photocatalytic coating can be fixed to the surface of the base material by sintering the photocatalytic particles as described later. it can. Alternatively, a thin film of an amorphous photocatalyst precursor may be fixed to the surface of a substrate and heated to crystallize to convert it into a photocatalyst having photoactivity. When the base material is made of a non-heat resistant material such as plastics or the base material is painted with a paint, a photooxidative paint containing a photocatalyst is applied to the surface as described later. By curing, a photocatalytic coating can be formed. When manufacturing an anti-fog mirror, it is possible to coat the front surface of the mirror on which the reflective coating has been formed in advance with a photocatalytic coating, or to form a reflective coating on the substrate before, after, or during the coating process. it can.

【0018】

photocatalyst The photocatalyst used in the photocatalytic coating of the present invention includes titania (TiO).₂) Is the most preferable. Titania is harmless, chemically stable, and inexpensively available. Furthermore, titania has a high bandgap energy, and therefore requires ultraviolet rays for photoexcitation and does not absorb visible light in the process of photoexcitation, so that color development due to complementary color components does not occur. Therefore, it is particularly suitable for coating transparent members such as glass, lenses and mirrors. Both anatase and rutile can be used as titania. The advantage of anatase-type titania is that a sol in which very fine particles are dispersed is easily available on the market, and a very thin thin film can be easily formed. On the other hand, rutile-type titania has an advantage that it can be sintered at a high temperature and a film having excellent strength and wear resistance can be obtained. As shown in FIG. 1, rutile-type titania has a lower conduction band level than anatase-type, but can be used for the purpose of photocatalytic hyperhydrophilization. As shown in Fig. 2 (a), when the base material 10 is coated with a photocatalytic coating 12 made of titania and the titania is photoexcited by ultraviolet rays, water becomes a hydroxyl group (OH) by photocatalytic action.^-) Is chemically adsorbed on the surface, and as a result, the surface is considered to be superhydrophilic. Other photocatalysts that can be used in the photocatalytic coating of the present invention include ZnO and SnO, as shown in FIG.₂, SrTiO₃, WO₃, Bi₂O₃, Fe₂O₃There are metal oxides such as. Similar to titania, these metal oxides are considered to adsorb surface hydroxyl groups (OH-) because metal elements and oxygen are present on the surface. As shown in FIG. 2 (b), the photocatalytic coating may be formed by blending the photocatalytic particles 14 into the layer 16 of the metal oxide. In particular, when a photocatalyst is blended with silica or tin oxide as described later, the surface can be highly hydrophilic.

【0019】

Photocatalytic coating film thickness When the base material is made of a transparent material such as glass, a lens, or a mirror, the film thickness of the photocatalytic coating is preferably 0.2 μm or less. By doing so, it is possible to prevent color development of the photocatalytic coating due to light interference. Further, the thinner the photocatalytic coating, the more transparent the base material can be ensured. Further, if the film thickness is reduced, the wear resistance of the photocatalytic coating is improved. The surface of the photocatalytic coating may be further provided with a wear-resistant or corrosion-resistant protective layer or other functional film that can be hydrophilized.

【0020】

Formation of photocatalyst layer by firing amorphous titania When the base material is made of a heat-resistant material such as metal, ceramics, or glass, a photocatalytic coating with excellent wear resistance that exhibits superhydrophilicity such that the contact angle with water is 0 °. One of the preferred ways to form is to first coat the surface of the substrate with amorphous titania and then phase change the amorphous titania to crystalline titania (anatase or rutile) by firing. One of the following methods can be adopted for the formation of amorphous titania. (1) Hydrolysis and dehydration polycondensation of organic titanium compounds Hydrolysis inhibitors such as hydrochloric acid or ethylamine are added to titanium alkoxides such as tetraethoxytitanium, tetraisopropoxytitanium, tetran-propoxytitanium, tetrabutoxytitanium, tetramethoxytitanium, and such as ethanol and propanol. After diluting with alcohol and then partially or completely hydrolyzing, the mixture is applied to the substrate by spray coating, flow coating, spin coating, dip coating, roll coating or other coating method. Apply to the surface of, and from room temperature to 200^。Dry at temperature C. Drying completes the hydrolysis of the titanium alkoxide to produce titanium hydroxide, and the dehydration polycondensation of titanium hydroxide forms a layer of amorphous titania on the surface of the substrate. Instead of the titanium alkoxide, other organic titanium compounds such as titanium chelates or titanium acetates may be used. (2) Formation of amorphous titania by inorganic titanium compound Inorganic titanium compounds such as TiCl₄Or Ti (SO)₄)₂The acidic aqueous solution of the above is applied to the surface of the base material by spray coating, flow coating, spin coating, dip coating, and roll coating. Then about 100 inorganic titanium compounds^。C ~ 200^。By drying at the temperature of C, it is subjected to hydrolysis and dehydration polycondensation to form a layer of amorphous titania on the surface of the substrate. Alternatively, TiCl₄Amorphous titania may be formed on the surface of the base material by chemical vapor deposition of. (3) Formation of amorphous titania by sputtering Amorphous titania is adhered to the surface of the base material by irradiating the target of metallic titanium with an electron beam in an oxidizing atmosphere. (4) Baking temperature The amorphous titania is calcined at a temperature at least higher than the crystallization temperature of anatase. 400^。C ~ 500^。Amorphous titania can be converted to anatase-type titania by firing at a temperature of C or higher. 600^。C ~ 700^。Amorphous titania can be converted to rutile-type titania by firing at a temperature of C or higher. (5) Formation of diffusion prevention layer When the base material is glass or glazed tile containing alkaline network-modifying ions such as sodium, it is preferable to form an intermediate layer such as silica in advance between the base material and the amorphous titania layer. By doing so, alkaline network-modifying ions are prevented from diffusing from the base material into the photocatalytic coating during firing of amorphous titania, and superhydrophilicity is realized so that the contact angle with water becomes 0 °. ..

【0021】

Photocatalytic layer made of silica-blended titania Another preferred method of forming a wear-resistant photocatalytic coating that is superhydrophilic to the extent that the contact angle with water is 0 ° is based on a photocatalytic coating consisting of a mixture of titania and silica. It is to form on the surface. The ratio of silica to the total of titania and silica can be 5 to 90 mol%, preferably 10 to 70 mol%, more preferably 10 to 50 mol%. One of the following methods can be adopted for forming a photocatalytic coating composed of silica-blended titania. (1) A suspension containing anatase-type or rutile-type titania particles and silica particles is applied to the surface of the base material, and sintered at a temperature below the softening point of the base material. (2) Tetraalkoxysilanes such as precursors of amorphous silica (for example, tetraethoxysilane, tetraisopropoxysilane, tetran-propoxysilane, tetrabutoxysilane, tetramethoxysilane, etc.; silanols which are hydrolysates thereof; Alternatively, a mixture of (polysiloxane) having an average molecular weight of 3000 or less) and crystalline titaniasol is applied to the surface of the substrate and hydrolyzed as necessary to form silanol, and then about 100.^。By heating at a temperature of C or higher and subjecting silanol to dehydration polycondensation, titania forms a photocatalytic coating bound to amorphous silica. In particular, the dehydration polycondensation temperature of silanol is about 200.^。When the temperature is C or higher, the degree of polymerization of silanol can be increased and the alkali resistance of the photocatalytic coating can be improved. (3) Amorphous titania precursor (organic titanium compound such as titanium alkoxide, chelate, or acetate, or TiCl₄Or Ti (SO)₄)₂A suspension of silica particles dispersed in a solution of an inorganic titanium compound such as) is applied to the surface of the substrate, and the titanium compound is applied from room temperature to 200. By subjecting to hydrolysis and dehydration polycondensation at the temperature of C, a thin film of amorphous titania in which silica particles are dispersed is formed. Next, the amorphous titania is phase-changed to crystalline titania by heating to a temperature equal to or higher than the crystallization temperature of titania and below the softening point of the substrate. (4) Amorphous titania precursor (organic titanium compound such as titanium alkoxide, chelate, or acetate, or TiCl₄Or Ti (SO)₄)₂Atypical silica precursors (eg, tetraethoxysilane, tetraisopropoxysilane, tetran-propoxysilane, tetrabutoxysilane, tetramethoxysilane, etc.) in a solution of an inorganic titanium compound such as tetraalkoxysilane; The hydrolyzate silanol; or polysiloxane with an average molecular weight of 3000 or less) is mixed and applied to the surface of the substrate. These precursors are then subjected to hydrolysis and dehydration polycondensation to form a thin film consisting of a mixture of amorphous titania and amorphous silica. Next, the amorphous titania is phase-changed to crystalline titania by heating to a temperature equal to or higher than the crystallization temperature of titania and below the softening point of the substrate.

【0022】

Photocatalytic layer made of tin oxide-containing titania Yet another preferred method of forming a wear-resistant photocatalytic coating that is superhydrophilic to the extent that the contact angle with water is 0 ° is based on a photocatalytic coating consisting of a mixture of titania and tin oxide. It is to be formed on the surface of the material. The ratio of tin oxide to the total of titania and tin oxide can be 1 to 95% by weight, preferably 1 to 50% by weight. One of the following methods can be adopted for forming a photocatalytic coating composed of tin oxide-containing titania. (1) A suspension containing anatase-type or rutile-type titania particles and tin oxide particles is applied to the surface of the base material, and sintered at a temperature below the softening point of the base material. (2) Amorphous titania precursor (organic titanium compound such as titanium alkoxide, chelate, or acetate, or TiCl₄Or Ti (SO)₄)₂A suspension of tin oxide particles dispersed in a solution of an inorganic titanium compound such as) is applied to the surface of the substrate, and the titanium compound is applied from room temperature to 200.^。By subjecting to hydrolysis and dehydration polycondensation at the temperature of C, a thin film of amorphous titania in which tin oxide particles are dispersed is formed. Next, the amorphous titania is phase-changed to crystalline titania by heating to a temperature equal to or higher than the crystallization temperature of titania and below the softening point of the substrate.

【0023】

Photocatalyst-containing silicone paint Contact angle with water is 0 Yet another preferred method of forming a photocatalytic coating that is superhydrophilic to the extent that it becomes a coating element consisting of an uncured or partially cured silicone (organopolysiloxane) or a silicone precursor. It is to use a coating composition in which particles of a photocatalyst are dispersed. When this coating composition is applied to the surface of the substrate, the coating film-forming element is cured, and then the photocatalyst is photoexcited, it is bonded to the silicon atom of the silicone molecule as described later in relation to Examples 13 and 14. The resulting organic group is replaced with a hydroxyl group by the photocatalytic action of the photocatalyst, and the surface of the photocatalytic coating is superhydrophilicized. This approach has several advantages. Since the photocatalyst-containing silicone paint can be cured at room temperature or relatively low temperature, it can be applied to a base material made of a non-heat resistant material such as plastics. This coating composition containing a photocatalyst can be applied to an existing base material that requires superhydrophilization of the surface at any time by brush coating, spray coating, roll coating or the like. Superhydrophilization of the photocatalyst by photoexcitation can be easily performed even with a light source such as sunlight. Further, when a coating film is formed on a plastically processable base material such as a steel sheet, the steel sheet can be easily plastically worked after the coating film is cured and before being photoexcited. Prior to photoexcitation, organic groups are bonded to the silicon atoms of the silicone molecule, and therefore the coating film has sufficient flexibility to easily plastically process the steel plate without damaging the coating film. Can be done. After the plastic working, if the photocatalyst is photoexcited, the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by the photocatalytic action, and the surface of the coating film becomes superhydrophilic. Since the photocatalyst-containing silicone paint has a siloxane bond, it has sufficient resistance to the photooxidation action of the photocatalyst. Yet another advantage of the photocatalytic coating consisting of a photocatalytic coating is that once the surface is superhydrophilic, it remains superhydrophilic for a long time even when kept in the dark, like a fluorescent lamp. Restores super hydrophilicity even with the light of indoor lighting

【0024】

The coating film-forming elements include methyltrichlorosilane, methyltribromsilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltrit-butoxysilane; ethyltrichlorosilane, ethyltribromsilane, and ethyltrimethoxy. Silane, ethyltriethoxysilane, ethyltriisopropoxysilane, ethyltri t-butoxysilane; n-propyltrichlorosilane, n-propyltribromsilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltri Isopropoxysilane, n-propyltrit-butoxysilane; n-hexyltrichlorosilane, n-hexyltribromsilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-hexyltriisopropoxysilane, n- Hexyltri t-butoxysilane; n-decyltrichlorosilane, n-decyltribromsilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n-decyltriisopropoxysilane, n-decyltri t-butoxysilane; n -Octadecyltrichlorosilane, n-octadecyltribromsilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octadecyltriisopropoxysilane, n-octadecyltri t-butoxysilane; Silane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltrit-butoxysilane; tetrachlorosilane, tetrabromsilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane; Didimethyldichlorosilane, dimethyldibromosilane, dimethyldimethoxysilane, dimethyldiethoxysilane; diphenyldichlorosilane, diphenyldiblomsilane, diphenyldimethoxysilane, diphenyldiethoxysilane;Phenylmethyldichlorosilane, phenylmethyldibromsilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane; trichlorohydrosilane, tribromhydrosilane, trimethoxyhydrosilane, triethoxyhydrosilane, triisopropoxyhydrosilane, trit-butoxyhydrosilane; vinyl Trichlorsilane, Vinyltribromsilane, Vinyltrimethoxysilane, Vinyltriethoxysilane, Vinyltriisopropoxysilane, Vinyltrit-butoxysilane; Trifluoropropyltrichlorosilane, Trifluoropropyltribromsilane, Trifluoropropyltrimethoxysilane, Trifluoropropyltriethoxysilane, trifluoropropyltriisopropoxysilane, trifluoropropyltrit-butoxysilane; γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxy Propyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxysilane, γ-glycidoxypropyltri t-butoxysilane; γ-methacryloxipropylmethyldimethoxysilane, γ- Metaacryloxypropylmethyldiethoxysilane, γ-metaacryloxypropyltrimethoxysilane, γ-metaacryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-methacryloxypropyltri t-butoxy Silane; γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropyltrit -Butoxysilane;γ-Mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltriisopropoxysilane, γ-mercaptopropyltri t-butoxy Silanes; β- (3,4-epylcyclohexyl) ethyltrimethoxysilane, β- (3,4-epylcyclohexyl) ethyltriethoxysilane; and their partial hydrolysates; and mixtures thereof can be used. it can.

【0025】

In order to ensure good hardness and smoothness of the silicone coating film, it is preferable to contain 10 mol% or more of the three-dimensional crosslinked siloxane. Further, in order to provide sufficient flexibility of the coating film while ensuring good hardness and smoothness, it is preferable to contain 60 mol% or less of the two-dimensional crosslinked siloxane. Further, in order to increase the rate at which the organic group bonded to the silicon atom of the silicone molecule is replaced with the hydroxyl group by photoexcitation, a silicone in which the organic group bonded to the silicon atom of the silicone molecule is composed of an n-propyl group or a phenyl group is used. Is preferable. It is also possible to use an organopolysilazane compound having a silazane bond instead of the silicone having a siloxane bond.

【0026】

Addition of antibacterial enhancer The photocatalytic coating can be doped with metals such as Ag, Cu and Zn. To dope the photocatalyst with Ag, Cu, or Zn, soluble salts of these metals can be added to the suspension of photocatalytic particles and the resulting solution can be used to form a photocatalytic coating. Alternatively, after forming the photocatalytic coating, soluble salts of these metals may be applied and photoreduced and precipitated by light irradiation. A photocatalytic coating doped with Ag, Cu, or Zn can kill bacteria attached to the surface. In addition, this photocatalytic coating suppresses the growth of microorganisms such as mold, algae and moss. Therefore, the surfaces of buildings, machinery, housing equipment, articles, etc. can be kept clean for a long period of time.

【0027】

Addition of photoactivity enhancer The photocatalytic coating can also be further doped with platinum group metals such as Pt, Pd, Rh, Ru, Os and Ir. Similarly, these metals can be doped into the photocatalyst by photoreduction precipitation or addition of a soluble salt. Doping the photocatalyst with a platinum group metal can enhance the redox activity of the photocatalyst and decompose contaminants adhering to the surface.

【0028】

Photoexcitation / UV irradiation When preventing fogging of transparent members such as glass, lenses, and mirrors, it is preferable to form a photocatalytic coating with a photocatalyst having a high bandgap energy and being photoexcited only by ultraviolet rays, such as titanium. That way, visible light is not absorbed by the photocatalytic coating and the glass, lenses and mirrors are not colored by complementary color components. Anatase-type titania can be photoexcited with ultraviolet rays having a wavelength of 387 nm or less, rutile-type titania having a wavelength of 413 nm or less, tin oxide having a wavelength of 344 nm or less, and zinc oxide having a wavelength of 387 nm or less. As the ultraviolet light source, indoor lighting such as a fluorescent lamp, an incandescent lamp, a metal halide lamp, and a mercury lamp can be used. Anti-fog glass, lenses and mirrors are exposed to ultraviolet light, and the surface is superhydrophilicized by photoexcitation of a photocatalyst. Under conditions exposed to sunlight, such as in the rearview mirror of a vehicle, the photocatalyst is naturally photoexcited by the ultraviolet rays contained in the sunlight. Photoexcitation can be performed or allowed to occur until the surface contact angle with water is about 10 ° or less, preferably about 5 ° or less, particularly about 0 °. Generally 0.001 mW / cm²If it is photoexcited with the ultraviolet illuminance of, it can be superhydrophilicized until the contact angle with water becomes about 0 ° in a few days. The illuminance of ultraviolet rays contained in the sunlight falling on the surface of the earth is about 0.1 to 1 mW / cm.²Therefore, the surface can be superhydrophilicized in a shorter time by exposing it to sunlight. When the surface of the base material is self-cleaned by rainfall or the adhesion of contaminants is prevented, a photocatalytic coating can be formed with a photocatalyst that can be photoexcited by ultraviolet rays or visible light. Articles coated with a photocatalytic coating are placed outdoors and exposed to sunlight and rainfall. When the photocatalytic coating is made of titania-containing silicone, it is preferable to photoexcite the photocatalyst with sufficient illuminance to replace the surface organic groups bonded to the silicon atoms of the silicone molecule with hydroxyl groups in a sufficient amount. The most advantageous way to do this is to use sunlight. Once the surface is highly hydrophilic, the hydrophilicity persists even at night. Hydrophilicity is restored and maintained each time it is exposed to sunlight again. When providing the user with the base material coated with the photocatalytic coating of the present invention, it is desirable to make the photocatalytic coating superhydrophilic in advance.

【0029】

[Example]

The following examples show the industrial applicability of the present invention from various points of view.

【0030】

Example 1 Anti-fog mirror-An anti-fog photocatalytic coating with a silica layer in between Tetraethoxysilane Si (OC) in 86 parts by weight of ethanol solvent₂H₅)₄(Wako Pure Chemical Industries, Osaka) 6 parts by weight of pure water, 6 parts by weight of pure water, and 2 parts by weight of 36% hydrochloric acid as a hydrolysis inhibitor of tetraethoxysilane were added and mixed to prepare a silica coating solution. Since the solution generates heat due to mixing, the mixed solution was left to cool for about 1 hour. This solution is applied to the surface of a 10 cm square soda lime glass plate by the flow coating method, and 80^。It was dried at the temperature of C. As it dries, tetraethoxysilane is hydrolyzed and first silanol Si (OH).₄Subsequently, a thin film of amorphous silica was formed on the surface of the glass plate by dehydration polycondensation of silanol. Next, 0.1 part by weight of 36% hydrochloric acid as a hydrolysis inhibitor was added to a mixture of 1 part by weight of tetraethoxytitanium Ti (OC2H5) 4 (Merck) and 9 parts by weight of ethanol to prepare a titania coating solution, and this solution was prepared. Was applied to the surface of the glass plate in dry air by a flow coating method. The coating amount is 45 μg / cm in terms of titania.²And said. Since the hydrolysis rate of tetraethoxytitanium is extremely high, a part of tetraethoxytitanium is hydrolyzed at the application stage, and titanium hydroxide Ti (OH).₄Began to generate. Next, this glass plate is about 150 for 1 to 10 minutes.^。By keeping the temperature at C, the hydrolysis of tetraethoxytitanium was completed, and the produced titanium hydroxide was subjected to dehydration polycondensation to produce amorphous titania. In this way, a glass plate in which amorphous titania was coated on amorphous silica was obtained. 500 for this sample. The amorphous titania was converted to anatase-type titania by firing at the temperature of C. Since the lower layer of the amorphous titania coating is coated with amorphous silica, alkaline network-modifying ions such as sodium in the glass plate are not diffused from the glass substrate into the titania coating during firing. it is conceivable that. Next, a reflective coating of aluminum was formed on the back surface of this glass plate by vacuum vapor deposition to manufacture a mirror, and a # 1 sample was obtained.

【0031】

After leaving the # 1 sample in the dark for several days, 0.5 mW / cm on the surface of the sample using a 20 W blue light black (BLB) fluorescent lamp (Sankyo Denki, FL20BLB).²The illuminance of ultraviolet rays (ultraviolet rays having an energy higher than the bandgap energy of anatase-type titania-ultraviolet rays having a wavelength shorter than 387 nm-illuminance) was irradiated for about 1 hour to obtain # 2 sample. For comparison, a reflective coating of aluminum was formed on the back surface of a glass plate uncoated with silica and titania by vacuum deposition, and the sample was left in a dark place for several days to obtain a # 3 sample. The contact angle between the water of the # 2 sample and the water of the # 3 sample was measured by a contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd., Asaka City, Saitama Prefecture, type CA-X150). The detection limit on the low angle side of this contact angle measuring instrument was 1. The contact angle was measured 30 seconds after dropping water droplets on the sample surface from the microsyringe. The reading of the measuring instrument for water on the surface of the # 2 sample was 0 °, indicating superhydrophilicity. On the other hand, the contact angle of the # 3 sample with water was 30 to 40 °. Next, the antifogging property and the spread of adhered water droplets were evaluated for the # 2 sample and the # 3 sample. Anti-fog evaluation is about 80 in a 500 ml beaker^。300 ml of hot water of C was added, and then the sample was held on a beaker with the surface of the mirror facing down for about 10 seconds, and immediately after that, the presence or absence of fogging on the sample surface and the appearance of the examiner's face were evaluated. In sample # 3, the surface of the mirror was cloudy due to steam, and the image of the examiner's face was not well reflected, but in sample # 2, no cloudiness was observed, and the examiner's face was clearly reflected. To evaluate the spread state of the adhered water droplets, a large number of water droplets were dropped from above with a dropper on the surface of the mirror tilted at 45 °, and the appearance of the water droplets adhered and the examiner's face after the mirror was once made vertical. evaluated. In the # 3 sample, obtrusive isolated water droplets scattered on the surface of the mirror adhered, and the reflected image was disturbed by the refraction of light by the water droplets, making it difficult to clearly observe the reflected image. On the other hand, in the # 2 sample, the water droplets adhering to the surface of the mirror spread on the surface without forming isolated water droplets to form a uniform water film. Although some distortion was observed in the reflected image due to the presence of the water film, the reflected image of the examiner's face could be recognized sufficiently clearly.

【0032】

Example 2 Anti-fog mirror-photocatalytic coating made of silica-blended titania A thin film of amorphous silica was formed on the surface of a mirror (MFL3) made of Nippon Sheet Glass by the same method as in Example 1. Next, 0.69 g of tetraethoxysilane (Wako Pure Chemical Industries, Ltd.), 1.07 g of anatase-type titaniasol (Nissan Chemical, TA-15, average particle size 0.01 μm), 29.88 g of ethanol, and 0.36 g of pure water are mixed to prepare a coating solution. did. This coating solution was applied to the surface of the mirror by a spray coating method. This mirror for about 20 minutes about 150^。By keeping at the temperature of C, tetraethoxysilane was subjected to hydrolysis and dehydration polycondensation to form a coating on the surface of the mirror in which anatase-type titania particles were bound with an amorphous silica binder. The weight ratio of titania to silica was 1. After leaving this mirror in the dark for several days, 0.5mW / cm using BLB fluorescent light²A # 1 sample was obtained by irradiating with ultraviolet rays at the same illuminance for about 1 hour. When the contact angle of the surface of this mirror with water was measured with the same contact angle measuring device as in Example 1, the reading of the contact angle was 0 °. Next, the antifogging property and the spread of adhered water droplets were evaluated for the # 1 sample and the mirror MFL3 without a photocatalytic coating by the same method as in Example 1. In the anti-fog test, fogging was observed on the surface of the mirror with the mirror MFL3, and the image of the examiner's face was not well reflected. It was reflected. In the inspection of how the adhered water droplets spread, it was difficult to clearly observe the reflected image with the mirror MFL3 because the light was refracted by the water droplets dispersed on the surface and the reflected image was disturbed. , The water droplets adhering to the surface of the mirror spread on the surface to form a uniform water film, and some distortion was observed in the reflected image due to the presence of the water film, but the reflected image of the examiner's face was sufficiently clear. I was able to recognize it.

【0033】

Example 3 (anti-fog spectacle lens) First, a thin film of amorphous silica was formed on both sides of a commercially available spectacle lens by the same method as in Example 1. Next, after applying the same coating solution as in Example 2 to both sides of the lens by the spray coating method, about 150 for about 20 minutes.^。By keeping at the temperature of C, tetraethoxysilane was subjected to hydrolysis and dehydration polycondensation, and a coating in which anatase-type titania particles were bound with an amorphous silica binder was formed on both sides of the lens. After leaving this lens in the dark for several days, use a BLB fluorescent lamp to 0.5mW / cm.²It was irradiated with ultraviolet rays for about 1 hour at the illuminance of. When the contact angle of the surface of this lens with water was measured with the same contact angle measuring device as in Example 1, the reading of the contact angle was 0 °. This lens was attached to the right frame of the spectacles, and a normal lens was attached to the left frame for comparison. A few hours later, when the tester wore these glasses and took a bath for about 5 minutes, the normal lens on the left was cloudy due to steam and lost visibility, but the lens on the right with a photocatalytic coating that was exposed to UV light. There was no cloudiness. Next, when the examiner intentionally showered the glasses, annoying water droplets adhered to the normal lens on the left side and obstructed the field of vision, but the water droplets adhering to the right lens quickly became a water film. It expanded and a sufficient view was secured.

【0034】

Example 4 (Anti-fog glass-7 nm film thickness titania coating) Amorphous titania was formed on the surface of the glass plate by applying a titanium chelate-containing liquid to the surface of a 10 cm square soda lime glass plate and subjecting the titanium chelate to hydrolysis and dehydration polycondensation. 500 this glass plate^。It was calcined at the temperature of C to form a surface layer composed of anatase-type titania crystals. The film thickness of the surface layer was 7 nm. First, 0.5 mW / cm on the surface of the obtained sample using a BLB fluorescent lamp.²It was irradiated with ultraviolet rays for about 1 hour at the illuminance of. When the contact angle of the surface of this sample with water was measured with a contact angle measuring device (ERMA, model GI-1000, detection limit on the low angle side 3 °), the reading of the contact angle was less than 3 °. Next, 0.01mW / cm using a 20W white fluorescent lamp (Toshiba, FL20SW)²The time change of the contact angle was measured while irradiating the ultraviolet rays with the ultraviolet illuminance of. The results are shown in the graph in Fig. 3. As can be seen from this graph, the surface of the sample was maintained highly hydrophilic even by the weak ultraviolet rays emitted from the white fluorescent lamp. From this example, it can be seen that the surface is maintained at a high degree of hydrophilicity even if the film thickness of the photocatalytic titanium coating is as thin as 7 nm. This is extremely important for ensuring the transparency of a base material such as window glass.

【0035】

Example 5 (Anti-fog glass-Titania coating with a film thickness of 20 nm) A surface layer composed of anatase-type titania crystals was formed on the surface of the soda lime glass plate in the same manner as in Example 4. The film thickness of the surface layer was 20 nm. Similar to Example 4, first, a BLB fluorescent lamp was used on the surface of the obtained sample at 0.5 mW / cm.²After irradiating with ultraviolet rays for about 1 hour at the illuminance of 0.01 mW / cm using a white fluorescent lamp²The time change of the contact angle was measured while irradiating the ultraviolet rays with the ultraviolet illuminance of. The results are shown in the graph in Fig. 4. Also in this example, the surface of the sample was maintained highly hydrophilic by the weak ultraviolet rays of the white fluorescent lamp.

【0036】

Example 6 (Anti-fog glass-Effect of firing temperature of amorphous titania) In the same manner as in Example 1, a thin film of amorphous silica was first formed on the surface of a 10 cm square soda lime glass plate, and then a thin film of amorphous titania was formed on the thin film, and a plurality of samples were obtained. 450 each of these glass plates^。C, 475^。C, 500^。C, 525^。It was fired at a temperature of C. Examined by powder X-ray diffraction, 475^。C, 500^。C, 525^。Anatase-type crystalline titania was detected in the sample calcined at the temperature of C, and it was confirmed that amorphous titania was converted to anatase-type crystalline titania, but 450. No anatase-type titania was detected in the samples calcined with C. First, 0.5 mW / cm was used on the surface of the obtained glass plate using a BLB fluorescent lamp.²After irradiating with ultraviolet rays for about 3 hours with the ultraviolet illuminance of, 0.02 mW / cm using a white fluorescent lamp²The time change of the contact angle was measured using a contact angle measuring device (CA-X150) while irradiating with ultraviolet rays with the ultraviolet illuminance of. The results obtained are shown in Table 1.

【0037】

[table 1]

<img file="JPH10156999A_D0001.tif" />【0038】

As you can see from Table 1, 475^。C, 500^。C, 525^。It was confirmed that the contact angle was maintained at 0 ° and the surface of the glass plate was maintained superhydrophilic as long as the sample was fired at the temperature of C and anatase crystals were observed, as long as the ultraviolet rays of the white fluorescent lamp were continuously irradiated. Was done. But 450^。It was confirmed that the amorphous titania coating of the sample calcined with C had no photocatalytic activity and the contact angle increased with the passage of time. 475^。C, 500^。C, 525^。When the sample calcined at the temperature of C was blown, no fogging occurred on the surface of the sample.

【0039】

Example 7 (Anti-fog glass-Effect of diffusion of alkaline network modifying ions) A titanium coating solution similar to that in Example 1 was prepared, and this solution was applied to the surface of a 10 cm square soda lime glass plate by the flow coating method. The coating amount is 45 μg / cm in terms of titania as in Example 1.²And said. Do the same for this glass plate for about 150 for 1 to 10 minutes. Amorphous titania was generated on the surface of the glass plate by keeping it at the temperature of C. 500 for this sample. The amorphous titania was converted to anatase-type titania by firing at the temperature of C. After leaving this sample in the dark for several days, 0.5 mW / cm on the surface of the sample using a BLB fluorescent lamp.²The ultraviolet rays were irradiated for about 1 hour at the ultraviolet illuminance of. When the contact angle with water was measured with a contact angle measuring device (CA-X150), the contact angle was 3 °. The contact angle of this sample did not reach 0 ° because, in this example, the silica layer was not interposed between the glass substrate and the titania layer, as compared with Example 1. It is probable that during firing in C, alkaline network-modifying ions such as sodium diffused from the glass substrate into the titania coating, inhibiting the photocatalytic activity of anatase. Therefore, in order to realize superhydrophilicity such that the contact angle with water becomes 0 °, it is considered that it is better to interpose an intermediate layer of silica as in Example 1.

【0040】

Example 8 (Anti-fog glass-Formation of amorphous titania by sputtering) A metal titanium film is adhered to the surface of a 10 cm square soda lime glass plate by sputtering, and 500^。It was fired at a temperature of C. When examined by powder X-ray diffraction, it was observed that anatase-type titania was formed on the surface of the glass plate. It is probable that the metallic titanium was oxidized by firing to produce anatase. Immediately after firing, 0.5 mW / cm on the surface of the sample using a BLB fluorescent lamp²The contact angle with water was measured with a contact angle measuring device (CA-X150) while irradiating ultraviolet rays with the ultraviolet illuminance of the above, and the temporal change of the contact angle was observed. The results are shown in the graph in Fig. 5. As can be seen from this graph, the contact angle with water was maintained at less than 3 °. From this test, it was confirmed that the surface of the glass plate was maintained at a high degree of hydrophilicity by irradiation with ultraviolet rays even when the photocatalyst layer was formed by sputtering.

【0041】

Example 9 (anti-fog glass-ultraviolet illuminance 800 lux) A thin film of amorphous silica was formed on the surface of a 10 cm square soda lime glass plate by the same method as in Example 1. Next, the coating solution of Example 2 was applied to the surface of the glass plate by a spray coating method. This glass plate is about 150 for about 20 minutes. By keeping at the temperature of C, anatase-type titania particles formed a coating on the surface of the glass plate in which the anatase-type titania particles were bound with an amorphous silica binder. The weight ratio of titania to silica was 1. After leaving this glass plate in the dark for several days, 0.5 mW / cm using a BLB fluorescent lamp.²It was irradiated with ultraviolet rays for about 1 hour at the illuminance of. When the contact angle of the surface of this glass plate with water after irradiation with ultraviolet rays was measured with a contact angle measuring device (CA-X150), the contact angle was 0 °. Next, 0.004 mW / cm was used for this sample using a white fluorescent lamp.²It continued to be irradiated with ultraviolet rays for 4 days at an ultraviolet illuminance of (800 lux). The contact angle on the sample surface was maintained at less than 2 ° during irradiation. When I blew on the glass plate four days later, no cloudiness occurred. From the above, it was confirmed that the surface of the glass plate is maintained at a high degree of hydrophilicity by weak ultraviolet rays under indoor lighting such as a white fluorescent lamp, and the glass plate is prevented from becoming cloudy.

【0042】

Example 10 (Effect of anti-fog glass-silica / titania compounding ratio) Next, tetraethoxysilane (Wako Pure Chemical Industries, Ltd.), anatase-type titania sol (Nissan Chemical Industries, Ltd., TA-15), ethanol, and pure water are mixed to prepare four types of coating solutions with different mixing ratios of tetraethoxysilane and titania sol. did. The ratio of tetraethoxysilane to titania sol is 10 mol%, 30 mol%, 50 mol%, 70 mol in terms of the ratio of silica to the total of silica and titania after converting tetraethoxysilane to amorphous silica. Changed to%. These coating solutions are applied to the surface of a 10 cm square soda lime glass plate by the spray coating method, and about 150 for about 20 minutes.^。By keeping at the temperature of C, tetraethoxysilane was subjected to hydrolysis and dehydration polycondensation, and a coating in which anatase-type titania particles were bound with an amorphous silica binder was formed on the surface of the glass plate. After leaving these samples in the dark for 1 week, use a BLB fluorescent lamp to 0.3 mW / cm.²It was irradiated with ultraviolet rays for about 1 hour at the illuminance of. When the contact angles of the surfaces of these samples with water after irradiation with ultraviolet rays were measured with a contact angle measuring device (CA-X150), the contact angles were all 0 °. Then, among these samples, the samples having a silica ratio of 30 mol% and 50 mol% were 0.004 mW / cm using a white fluorescent lamp.²When ultraviolet rays were continuously irradiated for 3 days under the ultraviolet illuminance of No. 1, the contact angle of the sample surface was maintained at less than 3 ° during the irradiation.

【0043】

Example 11 (Anti-fog glass-rutile type photocatalytic coating) Tetra ethoxytitanium Ti (OC₂H₅)₄A titania coating solution was prepared by adding 0.1 part by weight of 36% hydrochloric acid as a hydrolysis inhibitor to a mixture of 1 part by weight of (Merck) and 9 parts by weight of ethanol. This coating solution was applied to the surfaces of a plurality of 10 cm square quartz glass plates in dry air by a flow coating method. The coating amount is 45 μg / cm in terms of titania.²And said. Next, these glass plates are placed on these glass plates for about 150 minutes for 1 to 10 minutes.^。By keeping at the temperature of C, tetraethoxytitanium was subjected to hydrolysis and dehydration polycondensation to form an amorphous titania coating on the surface of the glass plate. 650 of these samples^。C and 800^。Amorphous titania was crystallized by firing at a temperature of C. 650 as a result of powder X-ray diffraction^。The crystal type of the C calcined sample is anatase type, 800^。It was found that the crystal type of the C calcined sample was the rutile type. After leaving the obtained sample in the dark for 1 week, 0.3 mW / cm using a BLB fluorescent lamp.²It was irradiated with ultraviolet rays for 2 days at the illuminance of. When the contact angle was measured after irradiation with ultraviolet rays, the contact angle of the surface of each sample with water was also 0 °. From the above, it can be seen that the surface is maintained highly hydrophilic not only with anatase-type titania but also when the photocatalyst is rutile. From this, it seems that the photocatalytic hyperhydrophilization phenomenon is not necessarily the same as the photocatalytic redox reaction.

【0044】

Example 12 (Anti-fog glass-transparency test) In the same manner as in Example 1, a thin film of amorphous silica was first formed on the surface of a 10 cm square soda lime glass plate, and then a thin film of amorphous titania was formed on the thin film. This glass plate is 500. It was calcined at a temperature of C to convert amorphous titania to anatase-type titania. The obtained sample was left in the dark for several days. Next, place this glass plate in a desiccator (temperature 24. C, humidity 45-50%) with a built-in BLB fluorescent lamp, and 0.5 mW / cm.²The # 1 sample was obtained by irradiating with ultraviolet rays at the same illuminance for 1 day. The contact angle of the # 1 sample with water was measured and found to be 0 °. Next, remove the # 1 sample from the desiccator and take 60^。It was quickly transferred onto a warm bath held in C, and the transmittance was measured after 15 seconds. The measured transmittance was divided by the original transmittance to determine the change in transmittance due to fogging generated by the condensation of water vapor. The surface of the glass plate was coated with anatase-type titania in the same manner as in Example 7 to obtain a # 2 sample. Place the # 2 sample in the desiccator and place it in 0.5 mW / cm.²At the illuminance of, ultraviolet rays were irradiated until the contact angle with water became 3 °. Next, the # 2 sample was left in a dark place. At different time intervals, # 2 samples were removed from the dark and the contact angle with water was measured each time. In addition, once the # 2 sample is desiccator (temperature 24)^。C, humidity 45-50%), after equilibrating the temperature, 60 as in the # 1 sample^。It was quickly transferred onto a warm bath held in C, and the transmittance was measured 15 seconds later to determine the change in transmittance due to cloudiness generated by the condensation of water vapor. For comparison, the contact angles with water of commercially available lined glass, acrylic resin plate, polyvinyl chloride plate, and polycarbonate plate were measured. Furthermore, after transferring these plates into a desiccator under the same conditions and equilibrating the temperature, similarly, 60^。It was quickly transferred onto a warm bath held in C, and the transmittance was measured 15 seconds later to determine the change in transmittance due to cloudiness generated by the condensation of water vapor. The results obtained are shown in Table 2.

【0045】

[Table 2]

<img file="JPH10156999A_D0002.tif" />【0046】

From this result, it was confirmed that extremely high antifogging property is realized when the contact angle with water is 10 ° or less.

【0047】

Example 13 (Photocatalyst-containing silicone coating) This example relates to the discovery that irradiation of certain polymeric coatings containing a photocatalyst with ultraviolet light makes the coating highly hydrophilic. A 10 cm square aluminum substrate was used as the base material. In order to smooth the surface of the substrate, it was previously coated with a silicone layer. For this reason, the ratio of the weight of silica to the weight of trimethoxymethylsilane in liquid A (silica sol) and liquid B (trimethoxymethylsilane) of the paint composition "Grasca" of Nippon Synthetic Rubber (Tokyo) is set to 3. And apply this mixture to an aluminum substrate, 150^。It was cured at the temperature of C to obtain a plurality of aluminum substrates (# 1 sample) coated with a silicone base coat having a film thickness of 3 μm. Next, the # 1 sample was coated with a polymer coating material containing a photocatalyst. Silicone was selected as the coating element to prevent the coating element of the paint from deteriorating due to the photooxidative action of the photocatalyst. More specifically, anatase-type titania sol (Nissan Chemical Industries, Ltd., TA-15) and the above-mentioned "Grasca" solution A (silica sol) are mixed, diluted with ethanol, and then "Grasca" solution B is added to add the titania-containing paint. The composition for use was adjusted. The composition of this coating composition was 3 parts by weight of silica, 1 part by weight of trimethoxymethylsilane, and 4 parts by weight of titania. Apply this paint composition to the surface of # 1 sample, 150^。Curing at the temperature of C formed a topcoat in which anatase-type titania particles were dispersed in the silicone coating film, and a # 2 sample was obtained. Next, 0.5 mW / cm using a BLB fluorescent lamp for # 2 sample.²A # 3 sample was obtained by irradiating with ultraviolet rays at the same illuminance for 5 days. When the contact angle of the surface of this sample with water was measured with a contact angle measuring device (manufactured by ERMA), surprisingly, the reading of the contact angle was less than 3 °. The contact angle of the # 2 sample before UV irradiation was measured and found to be 70 °. The contact angle of the # 1 sample was measured and found to be 90 °. Furthermore, when the # 1 sample was irradiated with ultraviolet rays under the same conditions for the # 2 sample for 5 days and the contact angle was measured, the contact angle was 85 °. From the above, it was discovered that although silicone is inherently quite hydrophobic, it becomes highly hydrophilic when it contains a photocatalyst and when the photocatalyst is excited by ultraviolet irradiation.

【0048】

Example 14 (Man spectroscopic analysis) 22.8 mW / cm using a mercury lamp for the # 2 sample of Example 13²A # 4 sample was obtained by irradiating with ultraviolet rays for 2 hours under the ultraviolet illuminance of. Raman spectroscopic analysis was performed on the # 2 sample before irradiation and the # 4 sample after irradiation. For comparison, the # 1 sample was also irradiated with ultraviolet rays under the same conditions, and Raman spectroscopic analysis of the samples before and after irradiation was performed. The Raman spectrum is shown in the graph of Fig. 6. Since the Raman spectra of the # 1 sample before and after irradiation were the same, they are shown by curve # 1 in the graph of Fig. 6. Refer to the graph in Fig. 6, in the Raman spectrum of the # 2 sample, the wave number is 2910 cm.^-1A large peak of CH bond symmetric expansion and contraction of the sp3 hybrid orbital is observed at the position of, and the wave number is 2970 cm.^-1A large peak of CH-bonded inverse symmetric expansion and contraction of the sp3 hybrid orbital is observed at the position of. Therefore, it results in the presence of CH bonds in the # 2 sample. In the Raman spectrum of # 4 sample, the wave number is 2910 cm.^-1Position and 2970 cm^-1No peak is observed in any of the positions of. Instead, wide-width OH-bonded symmetric expansion and contraction with a peak at wavenumber 3200 cm-1 is observed. Therefore, it results in the absence of CH binding in the # 4 sample and instead the presence of OH binding. On the other hand, in the Raman spectrum of # 1 sample, the wave number is 2910 cm before and after irradiation.^-1A large peak of CH bond symmetric expansion and contraction of the sp3 hybrid orbital is observed at the position of 2970 cm.^-1A large peak of CH-coupled inverse symmetric expansion and contraction of the sp3 mixed orbit is observed at the position of. Therefore, it is confirmed that CH bonds are present in the # 1 sample. From the above, when the silicone containing the photocatalyst is irradiated with ultraviolet rays, the organic group bonded to the silicon atom of the silicone molecule represented by the following general formula (1) is replaced with a hydroxyl group by the photocatalytic action, and the formula (1) It is considered that the silicone derivative as shown in 2) is formed on the surface.

【0049】

[Chemical 1]

<img file="JPH10156999A_D0003.tif" />(1) (In the formula, R represents an alkyl group or an allyl group) [0050]

[Chemical 2]

<img file="JPH10156999A_D0004.tif" />(2) 【0051】

Example 15 (Anti-fog plastic plate-An anti-fog coating made of photocatalyst-containing silicone) In order to prevent the plastic base material from being deteriorated by the photocatalyst, the surface of the base material was previously coated with a silicone layer. Therefore, in the same manner as in Example 13, liquids A and B of "Grasca" of Japanese synthetic rubber are mixed so that the ratio of the weight of silica to the weight of trimethoxymethylsilane is 3, and the coating liquid is applied. It was adjusted. Apply this coating liquid to the surface of a 10 cm square acrylic resin plate, and 100^。It was cured at the temperature of C to obtain a plurality of acrylic resin plates (# 1) coated with a silicone base coat having a film thickness of 5 μm. Next, anatase-type titania sol (Nissan Chemical Industries, Ltd., TA-15) and the above-mentioned "Grasca" solution A are mixed, diluted with ethanol, and then "Grasca" solution B is added, and four types of coating solutions with different compositions are added. Was adjusted. The composition of these coating solutions was adjusted so that the ratio of the weight of titania to the sum of the weight of titania, the weight of silica and the weight of trimethoxymethylsilane was 5%, 10%, 50% and 80%, respectively. Each coating liquid was applied to the acrylic resin plate coated with the silicone layer, and 100^。Curing at the temperature of C formed a topcoat in which anatase-type titania particles were dispersed in the silicone coating film, and # 2 to # 5 samples were obtained. BLB fluorescent lamp 0.5mW / cm for # 1 ~ # 5 samples²The contact angle of the surface of these samples with water was measured with a contact angle measuring device (manufactured by ERMA) at different time intervals while irradiating with ultraviolet rays for up to 200 hours at the same illuminance, and the temporal change of the contact angle was observed. .. The results are shown in the graph in Fig. 7. As can be seen from the graph in Fig. 7, in the # 1 sample without the titania-containing layer, there is almost no change in the contact angle with water even when irradiated with ultraviolet rays. On the other hand, it can be seen that the # 2 to # 5 samples provided with the titania-containing top coat are hydrophilized until the contact angle with water becomes less than 10 ° in response to ultraviolet irradiation. In particular, it can be seen that the contact angle with water is 3 ° or less in the # 3 to # 5 samples in which the proportion of titania is 10% by weight or more. Furthermore, it should be noted that in the # 4 sample and the # 5 sample in which the proportion of titania is 50% by weight and 80% by weight, respectively, the contact angle with water becomes 3 ° or less by short-time ultraviolet irradiation. When the # 4 sample was blown, no cloudiness occurred. After leaving the # 4 sample in the dark for 2 weeks, the contact angle with water was measured with a contact angle measuring device (CA-X150), and the contact angle with water was 3 ° or less.

【0052】

Example 16 (pencil scratch test) A pencil scratch test was conducted to examine the wear resistance of the titania-containing topcoat. In the same manner as in Example 15, the surfaces of a plurality of 10 cm square acrylic resin plates were coated with a silicone base coat having a film thickness of 5 μm, and then top coats having different titania contents were coated. The proportion of titania in the top coat was 50% by weight, 60% by weight and 90% by weight, respectively. According to Japanese Industrial Standards (JIS) H8602, the surface of the sample was scratched with a pencil lead, and the hardest pencil lead from which the top coat was peeled off was detected. The same test was performed on a sample coated only with a base coat. The results are shown in the graph of Fig. 8. The topcoat with a titania ratio of 90% by weight was peeled off with a pencil lead with a hardness of 5B, but the topcoat with a titania ratio of 60% by weight could withstand a pencil lead with a hardness of H and exhibited sufficient wear resistance. .. Obviously, the wear resistance of the topcoat increases as the titania content decreases.

【0053】

Example 17 (Effect of film thickness) In the same manner as in Example 13, a silicone base coat having a film thickness of 5 μm was first formed on the surface of a 10 cm square aluminum plate, and then top coats containing anatase-type titania having different film thicknesses were formed on the surface. A sample was obtained. Topcoat film thickness of # 1 sample is 0.03 μm, topcoat film thickness of # 2 sample is 0.1 μm, topcoat film thickness of # 3 sample is 0.2 μm, topcoat film thickness of # 4 sample is 0.6 μm, # 5 The topcoat film thickness of the sample was 2.5 μm. 0.5 mW / cm for each sample with BLB fluorescent lamp²The time change of the contact angle of the sample surface with water was investigated using a contact angle measuring device (manufactured by ERMA) while irradiating with ultraviolet rays with the ultraviolet illuminance of. The results are shown in the graph of Fig. 9. As can be seen from the graph in Fig. 9, the surface of each sample is highly hydrophilic within 50 hours of irradiation, regardless of the film thickness, and the contact angle with water is 3. It became less than . In particular, it is noted that even if the film thickness of the titania-containing topcoat is 0.2 μm or less, sufficient photocatalytic activity can be obtained to make the surface of the topcoat highly hydrophilic. In this regard, it is generally known that when the film thickness of the transparent layer is 0.2 μm or more, color development due to light interference occurs. This example shows that if the film thickness of the top coat is 0.2 μm or less, the surface can be highly hydrophilic while preventing the color development of the top coat due to the interference of light. Next, the photodegradation performance of methyl mercaptan was investigated for # 1 to # 5 samples. Each sample was placed in a desiccator made of quartz glass capable of transmitting ultraviolet rays and having a volume of 11 liters, and nitrogen gas containing methyl mercaptan was injected so that the concentration of methyl mercaptan was 3 ppm. A 4W BLB fluorescent lamp is placed in the desiccator at a distance of 8cm from the sample, and 0.3mW / cm.²The ultraviolet rays were irradiated with the ultraviolet illuminance of. After 30 minutes, the gas in the desiccator was sampled, the concentration of methyl mercaptan was measured by gas chromatography, and the removal rate of methyl mercaptan was determined. The results are shown in the graph of Fig. 10. The graph of FIG. 10 shows that the photodecomposition performance of methyl mercaptan increases as the film thickness of the photocatalyst layer increases. As mentioned above in relation to the graph in Fig. 9 , the photocatalytic superhydrophilicization phenomenon is not affected by the film thickness, whereas the photocatalytic photodecomposition performance is clearly affected by the film thickness. I understand. Therefore, it seems that the photocatalytic hyperhydrophilization phenomenon is not necessarily the same as the photocatalytic redox reaction conventionally known in the field of photocatalyst.

【0054】

Example 18 (Highly hydrophilic photocatalytic coating made of silicone containing titania) In the same manner as in Example 13, a silicone base coat having a film thickness of 5 μm was first formed on the surface of a 10 cm square aluminum plate. Next, anatase-type titania sol (Nissan Chemical Industries, Ltd., TA-15) and the above-mentioned "Grasca" solution B (trimethoxymethylsilane) were mixed and diluted with ethanol to prepare a composition for a titania-containing paint. The ratio of the weight of trimethoxymethylsilane to the weight of titania was 1. This paint composition is applied to an aluminum plate and 150^。Curing at temperature C formed a topcoat in which anatase-type titania particles were dispersed in the silicone coating. The film thickness of the top coat was 0.1 μm. Next, 0.5 mW / cm was used for this sample using a BLB fluorescent lamp.²It was irradiated with ultraviolet rays for one day at the illuminance of. When the contact angle of the surface of this sample with water was measured with a contact angle measuring device (CA-X150), the reading of the contact angle was 0 °. Furthermore, the contact angle with water was measured every week while storing this sample in a dark place for 3 weeks. The contact angles are shown in Table 3.

【0055】

[Table 3]

<img file="JPH10156999A_D0005.tif" />【0056】

As can be seen from Table 3, once the photocatalytic surface is superhydrophilic, it remains superhydrophilic for a considerable period of time without photoexcitation.

【0057】

Example 19 (Antibacterial enhancer-Ag-added photocatalyst) In the same manner as in Example 1, a thin film of amorphous silica and a thin film of amorphous titania were formed on the surface of a 10 cm square soda lime glass plate, and this sample was used as 500.^。Baking at a temperature of C converted amorphous titania to anatase-type titania to obtain # 1 sample. Next, apply a 1 wt% silver lactate aqueous solution to the surface of the # 1 sample, place a 20 W BLB fluorescent lamp at a distance of 20 cm from the sample, turn it on, irradiate the sample with ultraviolet rays for 1 minute, and # 2 A sample was obtained. By irradiation with ultraviolet rays, silver lactate was photoreduced to precipitate silver, and the surface of the sample was hydrophilized by the photocatalytic action of titania. The # 1 sample was also irradiated with ultraviolet rays under the same conditions. When the contact angle between the surface of the # 1 sample and the # 2 sample with water was examined using a contact angle measuring device (manufactured by ERMA), all of them were less than 3 °. Furthermore, when these samples were blown, no fogging occurred. For comparison, when the soda lime glass plate of the base material was examined, the contact angle with water was 50 °, and when it was blown, it easily became cloudy. Next, the antibacterial performance of the # 1 sample, the # 2 sample, and the soda lime glass plate was investigated. Escherichia coli The culture broth obtained by shaking the W3110 strain overnight was washed centrifugally and diluted 10,000-fold with sterilized distilled water to prepare the bacterial broth. 0.15 ml (10000-50000 CFU) of this bacterial solution was dropped onto three 10 cm square slide glasses, and each slide glass was previously sterilized with 70% ethanol and brought into close contact with # 1 and # 2 samples and a soda lime glass plate. , A white fluorescent lamp was irradiated from the front of the slide glass at an illuminance of 3500 lux for 30 minutes. Next, the bacterial solution of each sample was wiped off with sterile gauze, collected in 10 ml of physiological saline, and the collected bacterial solution was applied to ordinary agar medium, and then 37.^。Incubated in C for 1 day. The number of E. coli colonies on the medium was counted to determine the survival rate of E. coli. As a result, the survival rate of E. coli was 70% or more for the # 1 sample and the soda lime glass plate, but less than 10% for the # 2 sample. This test shows that when the photocatalyst is doped with Ag, the surface of the substrate is not only highly hydrophilic but also antibacterial.

【0058】

Example 20 (Antibacterial enhancer-Cu-added photocatalyst) A thin film of amorphous silica was formed on the surface of a 10 cm square soda lime glass plate by the same method as in Example 1, and a plurality of # 1 samples were obtained. Next, an amorphous titania thin film was formed on the surface of the # 1 sample in the same manner as in Example 1, and 500^。Amorphous titania was converted to anatase-type titania by firing at the temperature of C. A 1 wt% copper acetate ethanol solution is applied to the surface of this sample by a spray coating method, dried, and the sample is irradiated with ultraviolet rays for 1 minute with a 20 W BLB fluorescent lamp placed at a distance of 20 cm from the sample to obtain acetic acid. Copper ethanol was photoreduced and precipitated to obtain a # 2 sample in which titania crystals were doped with copper. When the # 2 sample was observed with the naked eye, it had sufficient light transmission. The antifogging property and the contact angle with water of the soda lime glass plate and the # 2 and # 1 samples (without titanium coating) immediately after production were inspected. The antifogging property test was carried out by blowing on the sample to cause fogging on the surface of the sample and observing the presence or absence of condensed water droplets with a microscope. The contact angle was measured with a contact angle measuring device (manufactured by ERMA). The results are shown in Table 4.

【0059】

[Table 4]

<img file="JPH10156999A_D0006.tif" />【0060】

In addition, 0.5 mW / cm of BLB fluorescent lamp for each of # 2 sample, # 1 sample and soda lime glass plate.²After irradiating with the ultraviolet illuminance of No. 1 for about 1 month, the antifogging property and the contact angle with water were similarly inspected. The results are shown in Table 5.

【0061】

[Table 5]

<img file="JPH10156999A_D0007.tif" />【0062】

Next, the antibacterial performance of the # 2 sample and the # 1 sample immediately after production and the soda lime glass plate was examined by the same method as in Example 19. As a result, the survival rate of E. coli was 70% or more for the soda lime glass plate and the # 1 sample, but less than 10% for the # 2 sample. Next, the deodorizing performance of the # 2 and # 1 samples and the soda lime glass plate immediately after production was investigated. Each sample was placed in a desiccator made of quartz glass capable of transmitting ultraviolet rays and having a volume of 11 liters, and nitrogen gas containing methyl mercaptan was injected so that the concentration of methyl mercaptan was 3 ppm. A 4W BLB fluorescent lamp is placed in the desiccator at a distance of 8cm from the sample, and 0.3mW / cm.²The ultraviolet rays were irradiated with the ultraviolet illuminance of. After 30 minutes, the gas in the desiccator was sampled, the concentration of methyl mercaptan was measured by gas chromatography, and the removal rate of methyl mercaptan was determined. The removal rate of methyl mercaptan was less than 10% in the # 1 sample and the soda lime glass plate, but the removal rate was 90% or more in the # 2 sample, showing good deodorizing performance.

【0063】

Example 21 (Antibacterial enhancer-Cu-added photocatalyst) Liquid A (silica sol) and liquid B (trimethoxymethylsilane) of Nippon Synthetic Rubber "Grasca" are mixed so that the ratio of the weight of silica to the weight of trimethoxymethylsilane is 3, and this mixed solution is 10 cm square. Apply to the surface of the acrylic resin plate of 100^。It was cured at the temperature of C to obtain an acrylic resin plate coated with a silicone base coat having a film thickness of 3 μm. Next, anatase-type titania sol (TA-15) and a 3 wt% copper acetate aqueous solution were mixed, and solution A (silica sol) of "Grasca" was further added and diluted with propanol. Next, solution B of "Grasca" was added to prepare a composition for a titania-containing paint. The composition of this coating composition was 3 parts by weight of silica, 1 part by weight of trimethoxymethylsilane, 4 parts by weight of titania, and 0.08 parts by weight of copper acetate in terms of metallic copper. This paint composition is applied to the surface of an acrylic resin plate, and 100^。It was cured at the temperature of C to form a top coat. Next, 0.5 mW / cm was used for this sample using a BLB fluorescent lamp.²The # 1 sample was obtained by irradiating with ultraviolet rays at the same illuminance for 5 days. The antifogging property, the contact angle with water, the antibacterial performance, and the deodorizing performance of the # 1 sample and the acrylic resin plate were examined by the same method as in Example 20. The acrylic resin plate had a contact angle with water of 70 °, and when it was blown, it became cloudy, but in the # 1 sample, the contact angle with water was 3 to 9 °, and cloudiness did not occur. Regarding antibacterial properties, the survival rate of Escherichia coli was 70% or more for the acrylic resin plate, but less than 10% for the # 1 sample. Regarding the deodorizing performance, the removal rate of methyl mercaptan was less than 10% in the acrylic resin plate, but the removal rate was 90% or more in the # 1 sample.

【0064】

Example 22 (photooxidation-reducing enhancer-Pt-added photocatalyst) In the same manner as in Example 1, a thin film of amorphous silica was first formed on the surface of a 10 cm square soda lime glass plate, and then a thin film of amorphous titania was formed on the thin film of amorphous silica. Amorphous titania was converted to anatase-type titania by firing at the temperature of C. Next, in this sample, platinum chloride hexahydrate H having a platinum concentration of 0.1% by weight was added.₂PtCl₆ 6H₂After applying 1 ml of O aqueous solution, 0.5 mW / cm using a BLB fluorescent lamp²After irradiating with ultraviolet rays for 1 minute at the same illuminance, platinum chloride hexahydrate was photoreduced to precipitate platinum, and a sample in which titania crystals were doped with platinum was obtained. After leaving the obtained sample for 1 day, 0.5 mW / cm using a BLB fluorescent lamp.²It was irradiated with ultraviolet rays for one day at the illuminance of. When the contact angle with water was measured after irradiation with ultraviolet rays, it was 0 °. Moreover, when the removal rate of methyl mercaptan was determined by the same method as in Example 20, it was 98%.

【0065】

Example 23 (Ruf cleaning performance and antifouling performance) 0.5 mW / cm using BLB fluorescent lamp for # 2 sample of Example 13²A # 3 sample was obtained by irradiating with ultraviolet rays at the same illuminance for 10 hours. When the contact angle of the surface of this sample with water was measured with a contact angle measuring device (manufactured by ERMA), the reading of the contact angle was less than 3 °. The outdoor dirt acceleration test equipment shown in Fig. 11 (a) and Fig. 11 (b) was installed on the roof of the building located in Chigasaki City. With reference to FIGS. 11 (a) and 11 (b), the device comprises an inclined sample support surface 22 supported by a frame 20 and is adapted to mount the sample 24. A roof 26 that slopes forward is fixed to the top of the frame. The roof is made of corrugated plastic plates, and the collected rain flows down in a streak on the surface of the sample 24 attached to the sample support surface 22. A plurality of # 3 sample, # 1 sample of Example 13 and # 2 sample of Example 13 were attached to the sample support surface 22 of this apparatus, and exposed to the weather conditions for 9 days from June 12, 1995. Table 6 shows the weather and rainfall during this period.

【0066】

[Table 6]

<img file="JPH10156999A_D0008.tif" />【0067】

When observed on June 14, vertical streaks were observed on the sample surface in # 1 sample. This is because during heavy rain the day before, combustion products such as carbon black in the atmosphere and hydrophobic stains such as urban dust are carried to the rain, and such hydrophobic stains are carried while the rain flows down the sample surface. Is considered to have adhered to the sample surface. On the other hand, no stain was observed in the # 3 sample. It is considered that this is because the surface of the sample is highly hydrophilic, so that the dirt does not easily adhere to the hydrophilic surface even if rainwater containing hydrophobic dirt flows down, and the dirt is washed away by rainfall. In the # 2 sample, mottled stains were observed. This is because the photocatalyst film was not sufficiently irradiated with ultraviolet rays by sunlight after the # 2 sample that had not been irradiated with ultraviolet rays was attached to the test equipment, and the surface was non-uniformly hydrophilic. Conceivable. When observed on June 20, vertical streaks on the sample surface were significantly observed in the # 1 sample without the photocatalytic coating. On the other hand, no stain was observed in the # 3 sample and the # 2 sample with the photocatalytic coating. When the contact angle with water was measured, it was 70 ° for the # 1 sample, and 3 for both the # 2 and # 3 samples. It was less than . The contact angle of # 2 sample became less than 3 ° because the organic group bonded to the silicon atom of the silicone molecule in the top coat of # 2 sample became a hydroxyl group by photocatalytic action due to the irradiation of ultraviolet rays contained in sunlight. It was replaced, indicating that the topcoat was highly hydrophilic. It can be seen that the high hydrophilicity of the # 3 sample is maintained by sunlight irradiation.

【0068】

Example 24 (color difference test) For the # 1 sample and the # 2 sample of Example 23, the color difference on the surface was measured using a color difference meter (Tokyo Denshoku) before and one month after the attachment to the outdoor dirt acceleration test apparatus. For the color difference, ΔE * display was used according to Japanese Industrial Standards (JIS) H0201. Table 7 shows the color difference changes before and after the installation of the accelerated test equipment.

【0069】

[Table 7]

<img file="JPH10156999A_D0009.tif" />【0070】

Table 7 shows that a large amount of dirt was attached to the vertical streaks, which are the flow paths of rainwater, in the # 1 sample without the photocatalyst film, as compared with the # 2 sample with the photocatalyst film. Furthermore, it is found that there is a considerable difference in background contamination between the # 2 sample and the # 1 sample.

【0071】

Example 25 (cleaning performance of oil stains) Oleic acid was applied to the surfaces of the # 1 sample and the # 3 sample of Example 23, and each sample was immersed in water filled in a water tank while keeping the sample surface in a horizontal position. In sample # 1, oleic acid remained attached to the surface of the sample. On the other hand, in the # 3 sample, the oleic acid curled up into oil droplets, which were released from the surface of the sample and surfaced. When the surface of the base material is coated with the photocatalytic top coat in this way, the surface of the base material is maintained hydrophilic, and oily stains can be easily released from the surface in water to clean the surface. confirmed. This example shows that, for example, if a photocatalytic coating is provided on the surface of tableware and the photocatalyst is excited by ultraviolet rays, the tableware contaminated with oil can be easily cleaned by simply immersing it in water without using detergent. There is.

【0072】

Example 26 (Drying performance of a surface wet with water) After wetting the surfaces of the # 1 sample and the # 3 sample of Example 23 with water, they were left outdoors on a sunny day and left to air drying. The temperature is about 25^。It was C. After 30 minutes, when the # 1 sample was observed, water droplets remained on the surface of the sample. On the other hand, the surface of the # 3 sample was completely dry. In the # 3 sample with a photocatalytic coating, it is considered that the attached water droplets form a uniform water film, and therefore drying is promoted. This embodiment shows that, for example, even if a spectacle lens or a windshield of an automobile gets wet with water, it can be quickly dried.

【0073】

Example 27 (Tile with Highly Hydrophilic Surface-Titania Silica Conjunctiva) Anatase-type titania sol (Ishihara Sangyo, Osaka, STS-11) and colloidal silica sol (Nissan Chemical, Snowtex O) are mixed at a solid content ratio of 88:12, and a 15 cm square glazed tile (Toto Toki, Toto) Apply to the surface of AB02E01) by spray coating method, 800^。The sample was calcined at the temperature of C for 1 hour to obtain a sample coated with a coating composed of titania and silica. The film thickness was 0.3 μm. The contact angle with water immediately after firing was 5 °. The contact angle with water after leaving the sample in the dark for 1 week was still 5 °. 0.03 mW / cm on the surface of the sample using a BLB fluorescent lamp²After irradiating with ultraviolet rays for one day at the illuminance of ultraviolet rays, the contact angle with water became 0 °.

【0074】

Example 28 (Titania Silica Conjunctiva-Hydrophilicization under Indoor Lighting) Anatase-type titania sol (STS-11) and colloidal silica sol (Nissan Chemical Industries, Ltd., Snowtex 20) are mixed at a solid content ratio of 80:20, and the surface of a 15 cm square glazed tile (AB02E01) is spray-coated. Apply and 800^。The sample was calcined at the temperature of C for 1 hour to obtain a sample coated with a coating composed of titania and silica. The film thickness was 0.3 μm. The contact angle with water immediately after firing was 5 °. The contact angle with water after leaving the sample in the dark for 2 weeks was 14 °. 0.004 mW / cm on the surface of the sample using a white fluorescent lamp²After irradiating with ultraviolet rays for one day at the illuminance of ultraviolet rays, the contact angle with water became 4 °. Therefore, it was found that the hydrophilicity was sufficiently obtained even under indoor lighting.

【0075】

Example 29 (Titania Silica Conjunctiva-Silica Content) Multiple suspensions of anatase-type titania sol (STS-11) and colloidal silica sol (Nissan Chemical, Snowtex 20) mixed in different proportions were prepared. The mole fractions of silica in the solids of each suspension were 0%, 5%, 10%, 15%, 20%, 25% and 30%. 0.08 g of each suspension was evenly applied to the surface of separate 15 cm square glazed tiles (AB02E01) by the spray coating method, and 800^。The samples were calcined at the temperature of C for 1 hour to obtain a plurality of samples coated with a coating composed of titania and silica. The contact angle of each sample immediately after firing with water was as shown in the graph of FIG. As can be seen from the graph in FIG. 12, the addition of silica tends to lower the initial contact angle. Furthermore, the contact angle with water after being left in the dark for 8 days is shown in the graph of FIG. As can be seen by comparing the graph of FIG. 12 with the graph of FIG. 13, the loss of hydrophilicity due to leaving in the dark is small in the sample having a silica molar fraction of 10% or more. Then, 0.03 mW / cm on the surface of the sample using a BLB fluorescent lamp.²It was irradiated with ultraviolet rays for 2 days at the ultraviolet illuminance of. The contact angle with water after irradiation is shown in the graph of FIG. It can be seen that when silica is added to titania, hydrophilicity is easily restored by irradiation with ultraviolet rays. After that, the sample was left in a dark place for another 8 days, and the contact angle with water was examined. The results are shown in Fig. 15. It can be seen that when silica is added to titania, the loss of hydrophilicity is small even when left in a dark place after irradiation with ultraviolet rays. A pencil scratch test was conducted to examine the wear resistance of the titania silica sintered film. The results are shown in the graph of Fig. 16. It can be seen that the wear resistance increases as the mole fraction of silica increases.

【0076】

Example 30 (sludge test) A mixture of anatase-type titania sol (STS-11) and colloidal silica sol (Snowtex 20) (10% by weight of silica in solid content) is applied to a 15 cm square glazed tile (AB02E01) by 4.5 mg in terms of solid content. , 880^。Bake at temperature C for 10 minutes. 0.5 mW / cm for this sample using a BLB fluorescent lamp²A # 1 sample was obtained by irradiating with ultraviolet rays for 3 hours under the ultraviolet illuminance of. The contact angles between the # 1 sample and the water of the glazed tile (AB02E01) were 0 ° and 30 °, respectively. A powder mixture containing 64.3% by weight of yellow ocher, 21.4% by weight of calcined Kanto loam clay, 4.8% by weight of hydrophobic carbon black, 4.8% by weight of silica powder, and 4.7% by weight of hydrophilic carbon black in water at a concentration of 1.05 g / liter. The suspended slurry was prepared. The # 1 sample and glazed tile (AB02E01) tilted at 45 degrees were allowed to flow 150 ml of the above slurry and dried for 15 minutes, then 150 ml of distilled water was allowed to flow and dried for 15 minutes, and this cycle was repeated 25 times. The change in color difference and the change in glossiness before and after the test were investigated. The glossiness was measured according to the provisions of Japanese Industrial Standards (JIS) Z8741, and the change in glossiness was determined by dividing the glossiness after the test by the glossiness before the test. The results are shown in Table 8.

【0077】

[Table 8]

<img file="JPH10156999A_D0010.tif" />【0078】

Example 31 (Relationship between contact angle with water and self-cleaning performance and antifouling performance) Various samples were subjected to the same sludge test as in Example 30. The investigated samples were the # 1 sample of Example 30, the # 2 sample sample in which Titania was doped with copper, the glazed tile (AB02E01), the acrylic resin plate, and the artificial marble plate using polyester resin as a matrix (East). Ceramic equipment, ML03), polytetrafluoroethylene (PTFE) plate. For the # 2 sample, a 0.3 g spray coating method was applied to the # 1 sample of Example 30 with an aqueous solution of a monohydrate of copper acetate having a copper concentration of 50 μmol / g, dried, and then 0.4 mW / cm using a BLB fluorescent lamp.²It was obtained by photoreducing and precipitating copper acetate monohydrate by irradiating with ultraviolet rays for 10 minutes under the ultraviolet illuminance of. The results of the sludge test are shown in Table 9.

【0079】

[Table 9]

<img file="JPH10156999A_D0011.tif" />【0080】

Furthermore, various samples were subjected to the same fouling acceleration test as in Example 23 for one month. The samples used were the # 1 sample of Example 30, a glazed tile (AB02E01), an acrylic resin plate, an aluminum plate coated with a silicone base coat by the same method as in Example 13, and a PTFE plate. The results of the accelerated test are shown in Table 10. In Table 10, the color difference change represents the color difference change of the vertical streaks of the sample as in Example 24.

【0081】

[Table 10]

<img file="JPH10156999A_D0012.tif" />【0082】

For ease of understanding, the contact angles and color difference changes with water shown in Tables 9 and 10 are plotted in the graph of Fig. 17. In the graph of Fig. 17, curve A shows the relationship between the color difference change due to combustion products such as carbon black in the atmosphere and dirt such as urban dust in the dirt acceleration test and the contact angle with water, and curve B is sludge. The relationship between the color difference change due to sludge and the contact angle with water in the test is shown. As can be clearly seen from the curve A, as the contact angle of the base material with water increases, the contamination by combustion products and urban dust becomes more noticeable, referring to the graph in FIG. This is because pollutants such as combustion products and urban dust are basically hydrophobic and therefore tend to adhere to hydrophobic surfaces. On the other hand, curve B shows that sludge stains peak in the range of 20 ° to 50 ° in contact with water. This is because inorganic substances such as mud and soil originally have hydrophilicity with a contact angle of about 20 to 50 ° with water, and easily adhere to a surface having similar hydrophilicity. Therefore, the surface should be hydrophilic with a contact angle of 20 ° or less with water, or the contact angle with water should be 60 °. It can be seen that if it is made more hydrophobic, it is possible to prevent the adhesion of inorganic substances to the surface. When the contact angle with water is 20 ° or less, the dirt caused by sludge is reduced. When the surface becomes highly hydrophilic with the contact angle with water of 20 ° or less, the affinity for water is more than the affinity for inorganic substances. This is because water that preferentially adheres to the surface inhibits the adhesion of the inorganic substance, and the inorganic substance that has adhered or is about to adhere is easily washed away by the water. From the above, in order to prevent both hydrophobic and hydrophilic stains from adhering to the surface of buildings, etc., or to prevent the stains accumulated on the surface from being washed away by rainfall and self-cleaning the surface. It can be seen that the contact angle of the surface with water should be 20 ° or less, preferably 10 ° or less, and more preferably 5 ° or less.

【0083】

Example 32 (Titania / Tin Oxide Conjunctiva-Glazed Tile) Anatase-type titania sol (STS-11) and tin oxide sol (Taki Kagaku, Kakogawa City, Hyogo Prefecture, average crystallite diameter 3.5 nm) are shown in the following Table 11 in various compounding ratios (tin oxide to the total of titania and tin oxide). Mix with (% by weight) and apply to the surface of a 15 cm square glazed tile (AB02E01) by the spray coating method, 750^。C or 800^。Baking at the temperature of C for 10 minutes gave # 1 sample to # 6 sample. For the # 2 sample, the # 4 sample, the # 5 sample, and the # 6 sample, silver was doped by further applying a 1 wt% silver nitrate aqueous solution after firing and performing photoreduction precipitation. Further, # 7 sample to # 9 sample were prepared by applying only tin oxide sol or only titania sol to the glazed tile and firing. The # 7 and # 9 samples were further doped with silver after firing. After each sample was left in the dark for 1 week, 0.3 mW / cm was applied to the surface of the sample using a BLB fluorescent lamp.²The contact angle with water was measured by irradiating with ultraviolet rays for 3 days under the ultraviolet illuminance of. The results are shown in Table 11.

【0084】

[Table 11]

<img file="JPH10156999A_D0013.tif" />【0085】

As can be seen from Table 11, in the # 8 and # 9 samples coated only with titania, the contact angle with water exceeds 10 °. This is because during firing, alkaline network-modifying ions such as sodium diffused from the glaze into titania, inhibiting the photocatalytic activity of anatase. In comparison, SnO₂The surface of the # 1 sample to the # 6 sample containing the above is highly hydrophilic. As can be seen from the # 7 sample, tin oxide is also a semiconductor photocatalyst like titania, and is effective in making the surface hydrophilic. For unknown reasons, this example shows that the addition of tin oxide to titania can overcome the effects of diffusion of alkaline network modifying ions.

【0086】

Example 33 (Titania Conjunctiva and Anti-Diffusion Layer-Glazed Tiles) Tetraethoxysilane (Ethyl 28, Corcote) is applied to the surface of a 15 cm square glazed tile (AB02E01) by a spray coating method, and about 150 for about 20 minutes. By keeping at the temperature of C, tetraethoxysilane was subjected to hydrolysis and dehydration polycondensation to form an amorphous silica layer on the surface of the glazed tile. Next, anatase-type titaniasol (STS-11) was applied to the surface of this glazed tile by a spray coating method, and 800.^。Bake at temperature C for 1 hour. For comparison with this sample, the # 8 sample of Example 32 was left in a dark place for 1 week, and then 0.3 mW / cm on the surface of the sample using a BLB fluorescent lamp.²The contact angle with water was measured by irradiating with ultraviolet rays for one day at the ultraviolet illuminance of. In the # 8 sample of Example 32, the contact angle with water was 12 °, but in the sample with the amorphous silica layer interposed, the contact angle with water was hydrophilized to less than 3 °. The amorphous silica layer is considered to be effective in preventing the diffusion of alkaline network-modifying ions in the glaze.

【0087】

Example 34 (Amorphous Titania Fired Film and Anti-Diffusion Layer-Glazed Tiles) In the same manner as in Example 1, a thin film of amorphous silica was first formed on the surface of a 15 cm square glazed tile (AB02E01), and then a thin film of amorphous titania was formed on the thin film. 500 this tile. It was calcined at a temperature of C to convert amorphous titania to anatase-type titania. After leaving the obtained sample in the dark for several days, 0.5 mW / cm using a BLB fluorescent lamp.²A sample was obtained by irradiating with ultraviolet rays for one day at the illuminance of. The contact angle of this sample with water was measured and found to be 0 °. Similar to Example 33, the amorphous silica layer is considered to be effective in making the surface of the tile highly hydrophilic.

【0088】

Example 35 (Glazed tile-cleaning performance of oil stains) When oleic acid was applied to the surface of the # 1 sample of Example 30 and the tile was immersed in water filled in a water tank while keeping the tile surface in a horizontal position, the oleic acid curled up into oil droplets and formed on the tile. Released from the surface and surfaced. Also in this embodiment, if a photocatalytic coating is provided on the surface of ceramics such as tiles and tableware and the photocatalyst is excited by ultraviolet rays, the oily surface can be easily removed by simply immersing the ceramics in water or wetting them with water. It shows that it can be cleaned.

【0089】

Example 36 (Glass-Oil Stain Cleaning Performance) In the same manner as in Example 1, a thin film of amorphous silica was first formed on the surface of a 10 cm square soda lime glass plate, and then a thin film of amorphous titania was formed on the thin film. 500 this glass plate^。It was calcined at a temperature of C to convert amorphous titania to anatase-type titania. When oleic acid was applied to the surface of this glass plate and the glass plate was immersed in water filled in a water tank while keeping the glass plate surface in a horizontal position, the oleic acid curled up into oil droplets and became oil droplets on the surface of the glass plate. Released from and surfaced.

【0090】

Example 37 (Glass-Self-cleaning and antifouling performance) The sample of Example 36 was subjected to the same dirt acceleration test as in Example 23 for one month. Visual observation one month later revealed no vertical streaks.

【0091】

Example 38 (Glazed tile-Antibacterial enhancer-Ag doping) A film composed of titania and silica was formed on the surface of a 15 cm square glazed tile (AB02E01) in the same manner as in Example 27. Next, a 1 wt% silver lactate aqueous solution was applied to the surface of this tile, and silver lactate was photoreduced by irradiating with ultraviolet rays using a BLB fluorescent lamp to precipitate silver, and titania was doped with silver. A sample was obtained. When the contact angle with water was examined, it was 0 °. Next, when the antibacterial performance of this tile was examined by the same method as in Example 19, the survival rate of Escherichia coli was less than 10%.

【0092】

Example 39 (Glazed tile-Antibacterial enhancer (-Cu doping) A film composed of titania and silica was formed on the surface of a 15 cm square glazed tile (AB02E01) in the same manner as in Example 27. Next, an aqueous solution of 1 wt% copper acetate monohydrate is applied to the surface of this tile, and copper acetate is photoreduced by irradiating with ultraviolet rays using a BLB fluorescent lamp to precipitate copper, and titania is copper. Obtained a sample doped with. When the contact angle with water was examined, it was less than 3 °. Next, when the antibacterial performance of this tile was examined by the same method as in Example 19, the survival rate of Escherichia coli was less than 10%.

【0093】

Example 40 (Glazed tile-photooxidation-reducing enhancer) A film composed of titania and silica was formed on the surface of a 15 cm square glazed tile (AB02E01) in the same manner as in Example 27. Next, the surface of this tile was doped with platinum in the same manner as in Example 22. When the contact angle with water was examined, it was 0 °. Next, when the removal rate of methyl mercaptan was determined by the same method as in Example 20, it was 98%.

【0094】

Example 41 (Effect of Excitation Wavelength) The # 8 sample of Example 32 and the glazed tile without titania coating (AB02E01) for comparison were left in a dark place for 10 days, and then irradiated with ultraviolet rays under the conditions shown in Table 12 below using an Hg-Xe lamp. The temporal change of the contact angle with water was measured.

【0095】

[Table 12]

<img file="JPH10156999A_D0014.tif" />【0096】

The measurement results are shown in FIGS. 18 (a) to 18 (c). In FIGS. 18 (a) to 18 (c), the values plotted with white dots represent the contact angles of the # 8 sample of Example 32 with water, and the values plotted with black dots are glazed tiles without titania coating. Represents the contact angle of. As can be seen from FIG. 18 (c), ultraviolet rays having an energy lower than 387 nm (ultraviolet rays having a wavelength longer than 387 nm) corresponding to the bandgap energy of anatase-type titania do not become hydrophilic even when irradiated with ultraviolet rays. On the other hand, as shown in FIGS. 18 (a) and 18 (b), it can be seen that the surface of ultraviolet rays having an energy higher than the bandgap energy of anatase-type titania becomes hydrophilic in response to the irradiation of ultraviolet rays. .. From the above, it was confirmed that the hydrophilization of the surface is closely related to the photoexcitation of the photosemiconductor.

【0097】

Example 42 (Plastic plate coated with photocatalyst-containing silicone) A polyethylene terephthalate (PET) film (Fuji Xerox, OHP film for monochrome PPC, JF-001) was coated with the same composition for a titania-containing paint as in Example 18, 110. Curing at temperature C gave # 1 sample coated with titania-containing silicone. Furthermore, a water-based polyester paint (manufactured by Takamatsu Yushi, A-124S) was applied to another PET film (JF-001), and 110^。It was cured at the temperature of C to form a primer coat. On top of this primer coat, the same composition for titania-containing paint as in Example 18 was applied, and 110^。It was cured at the temperature of C to obtain a # 2 sample. Further, the same composition for a titania-containing paint as in Example 18 was applied to a polycarbonate (PC) plate, and 110. It was cured at the temperature of C to obtain a # 3 sample. Furthermore, apply water-based polyester paint (A-124S) to other polycarbonate plates, and 110^。After curing at the temperature of C to form a primer coat, the same composition for titania-containing paint as in Example 18 was applied, and 110^。It was cured at the temperature of C to obtain a # 4 sample. 0.6mW / cm using BLB fluorescent lamp on # 1 sample to # 4 sample, PET film (JF-001) and polycarbonate plate²The time change of the contact angle of the sample surface with water was measured while irradiating with ultraviolet rays at the illuminance of. The results are shown in Table 13.

【0098】

[Table 13]

<img file="JPH10156999A_D0015.tif" />【0099】

As can be seen from Table 13, the surface of the sample became hydrophilic with ultraviolet irradiation, and the surface became superhydrophilic after about 3 days. It is considered that this is because the organic group bonded to the silicon atom of the silicone molecule of the silicone molecule of the titania-containing silicone layer was replaced with a hydroxyl group by the photocatalytic action by photoexcitation as described above in relation to Example 14. As is well known, 0.6mW / cm²The illuminance of ultraviolet rays is almost equal to the illuminance of ultraviolet rays contained in the sunlight falling on the surface of the earth. Therefore, it is noted that superhydrophilization can be achieved by simply exposing the titania-containing silicone coating film to sunlight.

【0100】

Example 43 (Weather resistance test of photocatalyst-containing silicone) Carbon # 1 sample (silicone-coated aluminum substrate) and # 2 sample (aluminum substrate coated with titania-containing silicone coating) of Example 13 were subjected to carbon using a weather resistance tester (Suga Test Instruments Co., Ltd., WEL-SUN-HC). Rain spray for 12 minutes out of 60 minutes, temperature 40 while irradiating light with an arc lamp^。It was subjected to a weather resistance test under the condition of C. Weather resistance was evaluated by the gloss retention rate (100% of the gloss after the test with respect to the initial gloss). The test results are shown in Table 14.

【0101】

[Table 14]

<img file="JPH10156999A_D0016.tif" />【0102】

As can be seen from Table 14, the gloss retention was almost the same with or without titania. This indicates that the siloxane bond constituting the main chain of silicone is not broken by the photocatalytic action of titania. Therefore, even if the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group, it is considered that the weather resistance of the silicone is not affected.

【0103】

Although specific examples of the present invention have been described above, the present invention is not limited thereto, and various modifications and modifications can be made. Furthermore, the present invention can be applied to various fields other than the above-mentioned uses. For example, a hyperhydrophilic surface can be used to prevent the adhesion of air bubbles to the surface in water. In addition, the superhydrophilized surface can be used to form and retain a uniform water film. Furthermore, since the superhydrophilic photocatalytic coating has excellent affinity for living organisms, it can be used in the medical field such as contact lenses, artificial organs, catheters, and antithrombotic materials.

[Simple explanation of drawings]

[Figure 1]

The levels of the valence band and conduction band of various semiconductor photocatalysts that can be used in the present invention are shown.

[Figure 2]

It is a schematic cross-sectional view which shows the photocatalytic coating formed on the surface of a base material microscopically enlarged, and shows how the hydroxyl group is chemisorbed on the surface by photoexcitation of a photocatalyst.

[Fig. 3]

It is a graph which shows the temporal change of the contact angle with water with the ultraviolet irradiation of various samples of an Example.

[Fig. 4]

It is a graph which shows the temporal change of the contact angle with water with the ultraviolet irradiation of various samples of an Example.

[Fig. 5]

It is a graph which shows the temporal change of the contact angle with water with the ultraviolet irradiation of various samples of an Example.

[Fig. 6]

The Raman spectroscopic spectrum of the surface of the photocatalytic coating made of silicone is shown.

[Fig. 7]

It is a graph which shows the temporal change of the contact angle with water with the ultraviolet irradiation of various samples of an Example.

[Fig. 8]

It is a graph which shows the result of the pencil hardness test.

[Fig. 9]

It is a graph which shows the temporal change of the contact angle with water with the ultraviolet irradiation of various samples of an Example.

[Fig. 10]

It is a graph which shows the relationship between the film thickness of the photocatalytic coating made of silicone, and the decomposition performance of methyl mercaptan.

[Fig. 11]

It is a front view and the side view of the outdoor dirt acceleration test apparatus.

[Fig. 12]

It is a graph which shows the relationship between the molar ratio of silica in silica compound titania, and the contact angle with water.

[Fig. 13]

It is a graph which shows the relationship between the molar ratio of silica in silica compound titania, and the contact angle with water.

[Fig. 14]

It is a graph which shows the relationship between the molar ratio of silica in silica compound titania, and the contact angle with water.

[Fig. 15]

It is a graph which shows the relationship between the molar ratio of silica in silica compound titania, and the contact angle with water.

[Fig. 16]

It is a graph which shows the result of the pencil hardness test.

[Fig. 17]

It is a graph which shows the degree to which the surface having different hydrophilicity is contaminated by urban dust and sludge.

[Fig. 18]

It is a graph which shows the time change of the contact angle with water when the surface of a photocatalytic coating is irradiated with ultraviolet rays of different wavelengths.

[Explanation of symbols]

10: Base material 12: Photocatalytic coating