JPH1067543A - Photocatalytic hydrophilic parts material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a parts material having a hydrophilic surface, self-purifying property, antifouling property and cloud-proof property by forming a layer of a photocatalytic oxide such as TiO2 on the surface of glass, etc., through an acrylic silicone layer. SOLUTION: This photocatalytic hydrophilic parts material is obtained by the following method. An acrylic silicone layer is formed on the surface of a base material such as glass by coating and heat-treating. Then, a layer of a photocatalytic oxide (preferably having <=0.2μm film thickness) is formed on its surface by using a sol coating and baking method, an organic titanate method or an electronic beam depositing method, etc., to obtain a parts material having highly hydrophilic surface and exhibiting water-wetting property having <=10 (preferably 5 deg.) contact angle. Preferably, silica and silicone are further contained in the surface layer. The photocatalytic oxide is an oxide generating a conducting electron and a positive hole by a photoexcitation and anatase-type titanium oxide, rutile-type titanium oxide, tin oxide and dibismuth trioxide, etc., are preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for making a member surface highly hydrophilic and maintaining it. More specifically, the present invention relates to an anti-fog technology for preventing the fogging and water droplets from forming on a mirror, lens, glass, prism or other transparent member by making the surface of the member highly hydrophilic. The present invention also prevents the surface from being stained by highly hydrophilizing the surface of a building, a window glass, a mechanical device or an article,
Alternatively, the present invention relates to a technique of self-cleaning (self-cleaning) or easily cleaning a surface.

[0002]

2. Description of the Related Art It is often experienced that in cold weather, windshields and glazings of automobiles and other vehicles, glazings of buildings, lenses of glasses, and cover glasses of various instrument panels are fogged by condensed moisture. . In addition, mirrors and eyeglass lenses in bathrooms and washrooms are often fogged by steam. Furthermore,
Vehicle windshields and windows, building windows, vehicle back mirrors, eyeglass lenses, masks and helmet shields are subjected to rainfall and splashes, and when a large number of discrete water droplets adhere to the surface, the Can be dark, blurred, mottled, or cloudy, again losing visibility. Needless to say, the above "clouding" has a profound effect on safety and efficiency of various operations. For example, if the windshield or window glass of the vehicle or the back mirror of the vehicle is overcast or cloudy in cold weather or rainy weather, it is difficult to secure a view, and traffic safety is impaired. Fogging of the endoscope lens and the dental dentoscope hinders accurate diagnosis, surgery, and treatment. If the cover glass of the instrument panel becomes fogged, it becomes difficult to read the data.

It has been proposed to make the surface hydrophilic in order to eliminate the "clouding". For example, 3-1
No. 29357 discloses a method in which a polymer layer is provided on the surface of a base material, and this layer is irradiated with ultraviolet rays and then treated with an aqueous alkali solution to generate high-density acidic groups, whereby the surface of the polymer layer becomes hydrophilic. A mirror anti-fogging method is disclosed. However, with such acidic groups, the surface polarity is not sufficient and the surface loses hydrophilicity over time due to contaminants adhering to the surface,
It is considered that the anti-fog performance is gradually lost.

[0004] On the other hand, in the fields of construction and paints, stains on building exterior materials, outdoor buildings and their coatings have become a problem with environmental pollution. Dust and particles suspended in the air 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 building's outer walls. Furthermore, in the rain, the floating dust is carried by the rain and flows down on the outer wall of the building or the surface of the outdoor building. As a result, pollutants adhere to the surface along the path of rainwater. 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 inorganic pollutants such as urban dust and clay particles. It is thought that such a variety of contaminants complicates antifouling measures (Yoshinori Tachibana, "Method for Accelerated Testing of Contamination of Exterior Wall Finishing Materials", Proc. No., October 1989, p.
5-24).

According to conventional wisdom, in order to prevent dirt on the building exterior and the like, polytetrafluoroethylene (PT) is used.
Although water-repellent paints such as FE) were considered preferable, recently it has been considered that it is desirable to make the surface of the paint film as hydrophilic as possible for urban dust containing a large amount of hydrophobic components. (Polymer, Vol. 44, May 1995, p. 307). Therefore, a hydrophilic graft polymer
It has been proposed to paint a building at (Chemical Industry Daily, January 30, 1995). According to reports, this coating exhibits a hydrophilicity of 30 to 40 ° in contact angle with water. However, the contact angle of inorganic dust typified by clay minerals with water is from 20 ° to 50 °, and has an affinity for a graft polymer having a contact angle of 30 to 40 ° with water. It is thought that the coating of the graft polymer cannot prevent contamination by inorganic dust because it easily adheres.

[0006]

As described above, by making the surface of the member hydrophilic, it is possible to prevent the member from fogging or forming water droplets, and also to prevent the surfaces of buildings, window glasses, mechanical devices and articles from becoming dirty. Although there are proposals that can prevent blemishes or clean the surface by self-cleaning or can be easily cleaned, the effect was not sufficient because the surface could not be maintained at a high degree of hydrophilicity for a long time. In view of the above circumstances, an object of the present invention is to provide a member capable of maintaining a surface with a high degree of hydrophilicity for a long period of time.

[0007]

SUMMARY OF THE INVENTION The present invention is based on the discovery that, in a member having a surface layer containing a photocatalyst, the surface of the member is highly hydrophilized when the photocatalyst is photoexcited. This phenomenon is considered to proceed by the following mechanism. That is, when light having energy equal to or greater than the energy gap between the upper end of the valence band of the photocatalyst and the lower end of the conduction electron band is irradiated on the photocatalytic oxide, the electrons in the valence band of the photocatalyst are excited and the conduction electrons are excited. Then, holes are generated, and one or both of these actions probably gives polarity to the surface, and polar components such as water and hydroxyl groups are collected. And either or both conduction electrons and holes,
The cooperative action of the polar components breaks the chemical bond between the adsorbed surface and the contaminants chemically adsorbed on the surface, and causes the chemically adsorbed water to be adsorbed on the surface, further forming a physically adsorbed water layer on it. It is done.

In the present invention, a layer containing a photocatalytic oxide is formed on the surface of the base material via an acrylic silicon resin layer, and the surface layer exhibits hydrophilicity in response to photoexcitation of the photocatalyst. A photocatalytic hydrophilic member is provided. By interposing the acrylic silicone resin layer, the adhesion between the base material and the surface layer is improved. This tendency is particularly remarkable when the substrate is plastic. Further, it is preferable that the photocatalyst and the base material do not come into direct contact with each other even when the base material is made of a substance which is easily degraded by oxidation, such as the case where the base material is a plastic, through the acrylic silicon resin layer.

In a preferred embodiment of the present invention, the surface layer further contains silica. By containing silica, the surface is likely to exhibit a high degree of hydrophilicity near a water wetting angle of 0 °, and the hydrophilicity retention when held in a dark place is improved. The reason seems to be related to the fact that silica can store water in its structure.

[0010] In a preferred embodiment of the present invention, the surface layer further contains silicone.
When silicon is contained, at least a part of the organic group bonded to the silicon atom in the silicon is replaced by a hydroxyl group by photoexcitation of the photocatalyst, and a physical adsorption water layer is formed thereon. This makes it easy for the surface to exhibit a high degree of hydrophilicity close to the water wetting angle of 0 °, and improves the hydrophilicity retention when kept in a dark place.

[0011]

Next, a specific configuration of the present invention will be described. In the present invention, as shown in FIGS. 1 to 3, a layer containing a photocatalytic oxide is formed on the surface of the base material via an acrylic silicon resin layer. FIG. 1 shows a case where the surface layer is made of only a photocatalytic oxide. In this case, the oxide is used as the photocatalyst because the oxide is hydrophilic when no pollutants in the environment are adsorbed and / or adhered to the photocatalyst. This is because the contaminants can be eliminated, and thus the contaminants can easily exhibit hydrophilicity.

In FIG. 2, M represents a metal element. The metal element of M can be basically anything, for example, silicon, aluminum, tungsten, yttrium, molybdenum, platinum, ruthenium, zirconium, tin, iridium, germanium, calcium, magnesium, strontium, lead, barium, cerium, hafnium, niobium , Erbium, cadmium, gallium, thallium, bismuth, phosphorus, silver, boron and the like can be used. Therefore, in the case of FIG. 2, the outermost surface is made of a general inorganic oxide.
Also in this case, the oxide shows hydrophilicity in a state where the pollutants in the environment are not adsorbed and / or adhered, and the pollutants can be rejected by the photoexcitation action and the formation and increase of the adsorbed water layer based on the photoexcitation action. It has sex.

In FIG. 3, R represents an organic group. As described above, when silicon is present on the outermost surface, the hydrophilization reaction proceeds in two stages. That is, first, at least a part of the organic group bonded to the silicon atom in the silicon is replaced by the hydroxyl group by the photoexcitation of the photocatalyst. Next, by further photo-exciting the photocatalyst, a physically adsorbed water layer is formed thereon to exhibit hydrophilicity.

The term "highly hydrophilic" in the present invention means a state exhibiting water wettability of 10 ° or less, preferably 5 ° or less in terms of a contact angle with water. PCT / JP96 / 007
As shown in No. 33, if the surface of the member is less than 10 ° in terms of the contact angle with water, condensed water forms individual water droplets even if moisture or steam in the air is dewed. Without this, the tendency to form a uniform water film becomes remarkable. Therefore, the tendency that light scattering fogging does not occur on the surface becomes remarkable. Similarly, when a window glass, a vehicle back mirror, a vehicle windshield, an eyeglass lens, or a shield of a helmet is exposed to rainfall or splashing, discrete unsightly water droplets are not formed, and high visibility and visibility are achieved. As a result, the effects of ensuring vehicle safety, ensuring the safety of vehicles and traffic, and improving the efficiency of various tasks and activities are dramatically improved. Also, as shown in PCT / JP96 / 00733, if the surface of the member is in a state of 10 ° or less, preferably 5 ° or less in terms of a contact angle with water, urban dust,
Combustion products such as carbon black contained in exhaust gas from automobiles, hydrophobic contaminants such as oils and fats, sealant-eluting components, and inorganic clay contaminants are unlikely to adhere, and even if they do adhere, it will rain. It can be easily dropped by washing with water.

If the surface of the member can maintain the above-mentioned high hydrophilicity, in addition to the above-mentioned anti-fogging effect and surface cleaning effect, it also has an anti-static effect (dust-preventing effect), a heat insulating effect, an air-bubble preventing effect in water, heat exchange. The effect of improving the efficiency of the vessel, the effect of biocompatibility, and the like are exhibited.

The substrate to which the present invention can be applied is a transparent member when the above anti-fogging effect is expected, and glass, plastic, and the like can be suitably used as the material. Speaking of applicable base materials, mirrors such as vehicle back mirrors, bathroom mirrors, toilet mirrors, dental mirrors, road mirrors; spectacle lenses, optical lenses, camera lenses, endoscope lenses, Lenses such as illumination lenses, semiconductor lenses, and copier lenses; prisms; windows of buildings and towers; automobiles, railway vehicles, aircraft, ships, submersibles, snowmobiles, lowway gondolas, and amusement parks. Windowpanes for vehicles such as gondola and spacecraft; cars, railcars, aircraft, ships, submarines,
Windshields for vehicles such as snowmobiles, snowmobiles, motorcycles, lowway gondola, amusement park gondola, spaceships; protective goggles, sports goggles, protective Includes mask shield, sports mask shield, helmet shield, frozen food display case glass; measuring instrument cover glass; and film for attaching to the surface of the article. . When the surface cleaning effect is expected as a substrate to which the present invention can be applied, the material is, for example, metal, ceramics, glass, plastic, wood, stone, cement, concrete, fiber, cloth, Combinations thereof and laminates thereof can be suitably used. Speaking of applicable base materials, building materials, building exteriors, building interiors, window frames, window glasses, structural members, vehicle exteriors and coatings,
Exterior of machinery and equipment, dust cover and paint, traffic signs, various display devices, advertising towers, road sound barriers, railway sound barriers, bridges, exterior and paint of garlands, tunnel interior and paint, Insulators, solar cell covers, solar water heater heat collection covers, vinyl houses, vehicular lighting covers, housing equipment, toilets, bathtubs, washbasins, lighting fixtures, lighting covers, kitchenware, tableware, tableware Includes washer, dish dryer, sink, cooking range, kitchen hood, ventilator, and film for application to the surface of the article. When the antistatic effect is expected as a substrate to which the present invention can be applied, the material is, for example, metal, ceramics, glass, plastic, wood, stone, cement, concrete, fiber, cloth,
Combinations thereof and laminates thereof can be suitably used.
Speaking of applicable base materials, cathode ray tubes, magnetic recording media, optical recording media, magneto-optical recording media,
Diode tapes, video tapes, analog records, housing and parts and exteriors and paintings for household electrical appliances, housings and parts and exteriors and paintings for OA equipment products, building materials, building exteriors, building interiors, window frames, windows It includes glass, structural members, vehicle exteriors and coatings, exteriors of machinery and articles, dustproof covers and paintings, and films to be attached to the article surfaces.

A photocatalytic oxide is a light-sensitive material that emits light (excitation light) having an energy (ie, shorter wavelength) larger than the energy gap between the conduction electron band and the valence band of an oxide crystal. An oxide capable of generating conduction electrons and holes by the excitation of electrons (photoexcitation) in the valence band, including anatase-type titanium oxide, rutile-type titanium oxide, tin oxide, zinc oxide, bismuth trioxide, Tungsten trioxide, ferric oxide, strontium titanate and the like can be suitably used. The light source used for photoexcitation of the photocatalytic oxide is, for example, indoor lighting such as a fluorescent lamp, an incandescent lamp, a metal halide lamp, or a mercury lamp, the sun, or a light source that guides light from the light source through a low-loss fiber. Can be suitably used. In order for the substrate surface to be highly hydrophilized by photoexcitation of the photocatalytic oxide, the illuminance of the excitation light is 0.001 m
W suffices / cm ² or more, but preferably that it 0.01 mW / cm ² or more, and more preferably it 0.1 mW / cm ² or more.

It is preferable that the thickness of the surface layer is 0.2 μm or less. Then, it is possible to prevent the surface layer from being colored by light interference. Also, the thinner the surface layer, the more transparent the member can be. Further, when the film thickness is reduced, the wear resistance of the surface layer is improved. The surface of the surface layer may be further provided with a wear-resistant or corrosion-resistant protective layer capable of being made hydrophilic and other functional films. Preferably, the surface layer does not have a very high refractive index as compared to the substrate. Preferably, the refractive index of the surface layer is 2 or less. Then, light reflection at the interface between the base material and the surface layer can be suppressed. Metals such as Ag, Cu, and Zn can be added to the surface layer. The surface layer to which the metal is added,
Bacteria attached to the surface can be killed. Furthermore,
This surface layer inhibits the growth of microorganisms such as molds, algae and moss. Therefore, adhesion of dirt on the member surface due to microorganisms can be more effectively suppressed. Pt, P
A platinum group metal such as d, Rh, Ru, Os, Ir can be added. The surface layer to which the metal is added can enhance the oxidizing activity of the photocatalyst, and promote the decomposition of contaminants attached to the member surface.

As the acrylic silicone resin, silicon-
And a block copolymer of a polymethacrylate resin and an acrylic resin, and a composite of a polymethacrylate resin and a silicone resin. The content of the silicon component in the resin may be any as long as it is strong against oxidative deterioration by the photocatalyst, but the silicon content is preferably 5% to 80%, and particularly preferably 10% to 60%. For the purpose of increasing the surface strength or the flexibility, silica may be added to the acrylic silicone resin, two or more acrylic silicone resins may be mixed, or a silicone resin may be added. Here, as the silicone resin, a silicone resin, an alkyd-modified silicone resin, a urethane-modified silicone resin, a polyester-modified silicone resin, an epoxy-modified silicone resin, or the like can be used. Mixing a light stabilizer with the acrylic silicone resin is effective in improving durability. As the light stabilizer, a hindered amine type or the like can be used. In addition, an ultraviolet absorber such as triazole may be mixed.

The method of forming the intermediate layer made of acrylic silicone resin includes, for example, a spray coating method, a dip coating method, a flow coating method,
An acrylic silicone resin emulsion is applied by a method such as spin coating or roll coating, and
The heat treatment is performed at a temperature of about 0 ° C. or less.

Next, a method for forming the surface layer will be described. First, a production method in the case where the surface layer is made of only a photocatalyst will be described with reference to an example where the photocatalyst is an anatase type titanium oxide. In this case, there are roughly three methods. One method is a sol coating and baking method, the other method is an organic titanate method, and the other method is an electron beam evaporation method. (1) Sol coating and baking method An anatase type titanium oxide sol is sprayed on the surface of a substrate.
Coating method, dip coating method, flow coating
It is applied by a coating method, a spin coating method, a roll coating method, or the like, and baked. (2) Organic titanate method Titanium alkoxides (tetraethoxytitanium, tetramethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium, etc.), titanium acetate, titanium chelate, and other organic titanates are treated with a hydrolysis inhibitor (hydrochloric acid, Ethylamine, etc.), and alcohol (ethanol, propanol)
, Butanol, etc.), and after partially or completely proceeding the hydrolysis, the mixture is spray-coated, dip-coated. , Flow coating method, Spin coating
Coating method, roll coating method, etc.
dry. By drying, hydrolysis of the organic titanate is completed to produce titanium hydroxide, and a layer of amorphous titanium oxide is formed on the surface of the base material by dehydration-condensation polymerization of the titanium hydroxide. Thereafter, the amorphous titanium oxide is calcined at a temperature higher than the crystallization temperature of the anatase to cause a phase transition from the amorphous titanium oxide to the anatase titanium oxide. (3) Electron beam evaporation method An amorphous titanium oxide layer is formed on the surface of a substrate by irradiating a target of titanium oxide with an electron beam. After that, firing at a temperature higher than the crystallization temperature of the anatase,
Amorphous titanium oxide undergoes a phase transition to an anatase type titanium oxide.

Next, the case where the surface layer is composed of a photocatalyst and silica will be described by taking as an example the case where the photocatalyst is an anatase type titanium oxide. In this case, for example, there are the following three methods. One method is a sol coating and baking method, the other method is an organic titanate method, and the other method is a 4 method.
This is a functional silane method. (1) Sol coating and firing method A mixture of an anatase-type titanium oxide sol and silica sol is applied to the surface of a substrate by spray coating, dip coating, or the like.
It is applied by a coating method, a flow coating method, a spin coating method, a roll coating method, or the like, and baked. (2) Organic titanate method Titanium alkoxides (tetraethoxytitanium, tetramethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium, etc.), titanium acetate, titanium chelate, and other organic titanates are treated with a hydrolysis inhibitor (hydrochloric acid, Ethylamine, etc.) and silica sol are added, and alcohol (ethanol,
After diluting with a non-aqueous solvent such as propanol or butanol, etc. and then partially or completely allowing the hydrolysis to proceed, the mixture is spray-coated, dip-coated. Method, floating coating method,
It is applied by a method such as spin coating or roll coating, and dried. By drying, hydrolysis of the organic titanate is completed to produce titanium hydroxide, and a layer of amorphous titanium oxide is formed on the surface of the base material by dehydration-condensation polymerization of the titanium hydroxide. Thereafter, the amorphous titanium oxide is calcined at a temperature higher than the crystallization temperature of the anatase to cause a phase transition from the amorphous titanium oxide to the anatase titanium oxide. (3) Tetrafunctional silane method A mixture of tetraalkoxysilane (tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetramethoxysilane, etc.) and an anatase type titanium oxide sol is spray-coated on the surface of the substrate. Method, dip coating method, flow coating method, spin coating method, roll coating method, and the like, and if necessary, hydrolyze to form a silanol, and then heat, etc. The silanol is subjected to dehydration polycondensation by the method described above.

Next, the case where the surface layer is composed of a photocatalyst and a silicone will be described with reference to the case where the photocatalyst is an anatase type titanium oxide. The method in this case is to mix an uncured or partially cured silicone or a silicone precursor paint with an anatase type titanium oxide sol, and to prepare the silicone precursor as necessary. After the hydrolysis, the mixture is sprayed on the surface of the substrate,
It is applied by a dip coating method, a flow coating method, a spin coating method, a roll coating method, or the like, and a hydrolysis product of a silicone precursor is subjected to dehydration condensation polymerization by a method such as heating. Then, a surface layer composed of anatase type titanium oxide particles and silicone is formed. In the formed surface layer, at least a part of the organic group bonded to the silicon atom in the silicone molecule is replaced with a hydroxyl group by photoexcitation of the anatase type titanium oxide by irradiation with light including ultraviolet rays, Furthermore, a physisorption water layer is formed on it,
It exhibits a high degree of hydrophilicity. Here, the precursors of silicone include methyltrimethoxysilane, methyltriethoxysilane, methyltributoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltributoxysilane, and ethyltripropoxysilane. , Phenyltrimethoxysilane, phenyltriethoxysilane, phenyltributoxysilane,
Phenyltripropoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldibutoxysilane, dimethyldipropoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldibutoxysilane, diethyldipropoxysilane, phenylmethyldimethoxysilane, phenylmethyl Diethoxysilane, phenylmethyldibutoxysilane, phenylmethyldipropoxysilane, γ-glycidoxypropyltrimethoxysilane, a hydrolyzate thereof, and a mixture thereof can be suitably used.

[0024]

【Example】

Embodiment 1 FIG. First, a primer paint (Shin-Etsu Silicone, PC-7A) made of acrylic silicone resin is applied to the surface of a 10 cm square polycarbonate plate by a spray coating method, and then dried at 120 ° C. for 20 minutes. Then, the substrate was covered with an acrylic silicone resin layer. Next, silicon-based hard
A coating agent (Shin-Etsu Silicone, KP-85) was applied by a spray coating method and dried at 120 ° C. for 60 minutes to form a hard coat layer on the primer resin layer. . Further, the surface of the hard coat layer was treated with a corona surface treatment device (Kasuga Electric) using a wire electrode as an electrode, a gap of 2 mm between the electrode tip and the sample surface, a voltage of 26 kV, a frequency of 39 kHz, and a sample feed speed of 4.2 m. / Min condition,
A high frequency corona discharge treatment was performed to obtain a # 1 sample. On the other hand, 56 parts by weight of an anatase type titanium oxide sol (Nissan Chemical, TA-
15, an average particle diameter of 12 nm) and 33 parts by weight of silica sol (Nippon Synthetic Rubber, Glasca A liquid) were mixed, diluted with ethanol, and further mixed with 11 parts by weight of methyltrimethoxysilane (Nippon Synthetic rubber, Glaska B liquid). To prepare a coating composition containing titanium oxide. The above coating composition was used for # 1 sample,
It was applied by a flow coating method, and was cured by heat treatment at 120 ° C. for 30 minutes to obtain a # 2 sample. This # 2 sample
Ultraviolet light source (Sankyo Electric, Black Light Bull-(BL
B) Using a fluorescent lamp), apply 0.6 mW / cm ² to the surface of the sample.
The sample was irradiated with ultraviolet rays at an ultraviolet illuminance of about 48 hours to obtain a # 3 sample. For comparison, a 10 cm square polycarbonate plate sample was also prepared. First, a water drop was dropped on the # 3 sample and the polycarbonate plate sample, and the state after the drop was observed and the contact angle with water was measured. Here, the contact angle with water was measured using a contact angle measuring device (Kyowa Interface Science Co., Ltd., CA-X150).
Evaluation was made based on the contact angle with water after 2 seconds. As a result, when a water drop was dropped on the sample surface from the microsyringe in the # 3 sample, it was observed that the water droplet spread uniformly on the sample surface in the form of a water film. Further, the contact angle with water after 30 seconds was highly hydrophilized to about 0 °. On the other hand, in the case of the polycarbonate plate sample, when a water droplet was dropped on the surface of the sample from the microsyringe, the water droplet conformed slightly to the surface, but did not reach a uniform water film state. The contact angle with water after 30 seconds was 60 °.

Next, 1 part by weight of hydrophobic carbon black,
A slurry in which a powder mixture consisting of 1 part by weight of hydrophilic carbon black is suspended in water at a concentration of 1.05 g / liter.
Was prepared. # 3 sample inclined at 45 degrees and polycarbonate
150 ml of the above slurry was allowed to flow down and dried for 15 minutes on the board sample, and then 150 ml of distilled water was allowed to flow down and dried for 15 minutes. This cycle was repeated 25 times.
The color difference change before and after the test was measured using a color difference meter (Tokyo Denshoku). The color difference was represented by ΔE * according to Japanese Industrial Standard (JIS) H0201. As a result, the color difference change of the polycarbonate plate sample was as large as 20, whereas the color difference change of the # 3 sample was only 0.6.

For the # 3 sample, a pencil hardness test (Japanese Industrial Standard (JIS) H8602) was performed to examine the adhesion of the surface layer to the substrate. As a result, an excellent value of 3H was shown.

Embodiment 2 FIG. First, a 10 cm square polyethylene terephthalate (PET) film is subjected to a corona discharge treatment, and then a primer paint (Shin-Etsu Silicone, PC-7A) made of acrylic silicone resin is applied by a flow coating method. An acrylic silicon resin layer was formed by performing a heat treatment at 120 ° C. for 5 minutes. Next, after the corona discharge treatment of the acrylic silicon resin layer, a photocatalytic coating solution (containing anatase type titanium oxide and methyl silicate, and having a ratio of 1 in weight of titanium oxide to silica in weight of methyl silicate). (Alcohol dispersion) was applied by a flow coating method and dried at room temperature for 10 minutes to obtain a photocatalytic film. Soap water was applied to the back side of this film and adhered to the surface of a 10 cm mirror base material. After leaving this glass head plate in a dark place for several days, the surface of the sample was irradiated with ultraviolet rays at an ultraviolet illuminance of 0.5 mW / cm ² for about 1 hour using a BLB fluorescent lamp to obtain a # 4 sample. For comparison, a glass plate of 10 cm square was left in a dark place for several days #
Five samples were also prepared. First, a water drop was dropped on the # 4 sample and the # 5 sample, and the state after the drop was observed and the contact angle with water was measured. As a result, when a water drop was dropped from the micro syringe onto the sample surface, it was observed that the water droplet spread uniformly on the sample surface in a water film form. Further, the contact angle with water after 30 seconds was highly hydrophilized to about 0 °. On the other hand, in the case of the # 5 sample, when a water drop was dropped on the sample surface from the microsyringe, the water drop slightly adapted to the surface, but did not reach a uniform water film state. The contact angle with water after 30 seconds was 30 °. Next, # 4 sample and #
Five samples were blown to examine the occurrence of fogging. As a result, fogging occurred in the # 5 sample, but no fogging occurred in the # 4 sample. Further, the # 4 sample was left in a dark place for two days thereafter to obtain a # 6 sample. The # 6 sample was similarly observed after dropping and measured for a contact angle with water. As a result, when a water drop was dropped on the sample surface from the microsyringe of the # 6 sample, it was observed that the water droplet spread uniformly on the sample surface in the form of a water film. The contact angle with water after 30 seconds was maintained at about 3 °. Next, the # 6 sample was blown to examine whether or not fogging occurred. As a result, no fogging was observed.

[0028]

According to the present invention, the surface layer containing the photocatalyst particles is fixed to the surface of the base material via the acrylic silicone resin layer, so that the surface becomes highly hydrophilic in response to the photoexcitation of the photocatalyst. It is self-cleaning (self-cleaning) by rainfall, or can be cleaned by sprinkling or rinsing water, or it becomes difficult for combustion products and dust caused by rainwater to adhere, and the surface layer is firmly attached to the base material. Became fixed to.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the surface structure of a member according to the present invention.

FIG. 2 is a diagram showing another example of the surface structure of the member of the present invention.

FIG. 3 is a diagram showing another example of the surface structure of the member of the present invention.

Claims (3)

[Claims] 1. A layer containing a photocatalytic oxide is formed on a surface of a base material via an acrylic silicon resin layer, and the surface layer exhibits hydrophilicity in response to photoexcitation of the photocatalyst. A photocatalytic hydrophilic member. 2. A layer containing a photocatalytic oxide and silica is formed on the surface of a base material via an acrylic silicon resin layer, and the surface layer exhibits hydrophilicity in response to photoexcitation of the photocatalyst. A photocatalytic hydrophilic member, characterized in that: 3. A layer containing a photocatalytic oxide and silicon is formed on the surface of a base material via an acrylic silicon resin layer, and the surface layer becomes hydrophilic in response to photoexcitation of the photocatalyst. A photocatalytic hydrophilic member characterized by exhibiting.