JPH0975243A - Stainproof plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antifoulant plate on which oily staining is sticked can be easily cleaned. SOLUTION: An antifoulant plate which is arranged on the surrounding of an apparatus which is a cause for scattering staining and receives the staining is provided. The antifoulant plate has a surface layer contg. a photo- semiconductor and the surface exhibits hydrophilic properties in accordance with photo-excitation of the photo-semiconductor. When the surface of the antifoulant plate exhibits enough hydrophilic properties, the staining sticked on the surface becomes easy to remove.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antifouling plate such as a kitchen bag which is arranged around a kitchen stove and receives oil stains scattered from cooked food on the stove. In particular, it relates to an antifouling plate that easily removes the attached dirt.

[0002]

2. Description of the Related Art In a kitchen stove, when cooking using a frying pan or the like, dirt represented by oil is scattered around. The wall surface around the stove where this scattered dirt hits is
It is made of a material that easily removes adhered dirt (easy to clean). Alternatively, a partition is set up around the stove to catch the scattering of dirt. In the present specification, a member, such as a wall surface or a partition, that is arranged around a device (stove) that causes stains and receives the stains is referred to as an antifouling plate.
The antifouling plate is preferably made of tiles or the like, because it is desirable that the antifouling plate has a property of easily removing attached dirt.

[0003]

However, even with a tile antifouling plate, strong oil stains are difficult to remove. Especially, when the adhered oil is polymerized and solidified to form a glue, it is difficult to remove the dirt. An object of the present invention is to provide an antifouling plate that easily removes oil stains and the like that have adhered. Furthermore, it aims at providing the antifouling plate which also has the effect | action which decomposes the oil stain etc. which adhered.

[0004]

In order to solve the above-mentioned problems, an antifouling plate of the present invention is an antifouling plate which is arranged around a device which causes dirt emission and receives the dirt; It is characterized in that it has a surface layer containing, and the surface exhibits hydrophilicity in response to photoexcitation of the optical semiconductor. If the surface of the antifouling plate exhibits sufficient hydrophilicity, dirt attached to the surface will be easily removed.

In the present invention, it is preferable that the photo-semiconductor oxidize and decompose stains adhering to the antifouling plate by its photo-oxidation effect. It is possible to prevent the oil from polymerizing and solidifying to form a glue.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the antifouling plate of the present invention, the surface layer containing the above-mentioned optical semiconductor contains anatase type titanium oxide and silica, or anatase type titanium oxide and at least a part of silanolated silicone. It is preferable. These provide a hydrophilic surface with a very high degree of hydrophilicity. The degree of hydrophilicity is such that the contact angle with water is 10
It stands out in the range of ° or 3 ° or less. Also,
Since anatase type titanium oxide has a high band gap energy, it has a strong oxidative decomposition effect on dirt. Here, the content of titanium oxide in the surface layer is preferably 5 to 90% by volume. This is because the hydrophilicity and the activity of the redox reaction are good in this range. Further, Ag, Pt, Pd, R
It is preferable to add any one metal of u, Os, and Ir because the redox property can be more activated without impairing the hydrophilic property.

Next, the relationship between hydrophilicity and optical semiconductor will be described. The present inventor discovered that the surface of an optical semiconductor is highly hydrophilized when the optical semiconductor is photoexcited. That is, when the photo-semiconductive titania is photoexcited with ultraviolet rays, the surface is highly hydrophilized so that the contact angle with water is 10 ° or less, more specifically 5 ° or less, and particularly about 0 °, and It was discovered that irradiation with light maintains and restores a high degree of hydrophilicity, and that under certain conditions, a highly hydrophilized state is maintained even in a dark place for 3 weeks or longer.

When the light having a wavelength of energy higher than the band gap energy of the photosemiconductor is irradiated with sufficient illuminance for a sufficient time, the surface of the photosemiconductor-containing layer becomes hydrophilic. At present, the surface hydrophilization phenomenon caused by photoexcitation of an optical semiconductor cannot always be clearly explained. It seems that the hydrophilization phenomenon by the photo-semiconductor is not necessarily the same as the photo-decomposition of a substance by the photocatalytic redox reaction conventionally known in the field related to the application to the chemical reaction of the photo-semiconductor. In this regard, conventional dogma regarding the photocatalytic redox reaction is photoexcited by electron - hole pairs are generated, the generated electrons are superoxide ions by reducing surface oxygen (O ₂ ^-) to generate the hole by oxidizing the surface hydroxyl groups to produce the hydroxyl radical (· OH), these highly reactive oxygen species (O ₂ ^- and · O
The substance was decomposed by the redox reaction of H).

However, the hydrophilization phenomenon due to the photo-semiconductor is inconsistent with the conventional findings regarding the photocatalytic decomposition of substances in at least two respects. First, according to the conventional theory, in photo semiconductors such as rutile and tin oxide, the energy level of the conductor is not sufficiently high, so the reduction reaction does not proceed, and as a result, the electrons photoexcited by the conductor are not excited. It was thought that the electron-hole pairs generated by photoexcitation recombine without participating in the redox reaction. On the other hand, it was confirmed that the hydrophilization phenomenon caused by the optical semiconductor also occurs in the optical semiconductors such as rutile and tin oxide.

Secondly, conventionally, the decomposition of a substance by a photocatalytic oxidation-reduction reaction requires that the thickness of the optical semiconductor layer be at least 100 nm
It is thought that it will not happen unless it is above. On the other hand, hydrophilization with an optical semiconductor requires that the film thickness of the photocatalyst containing layer be several
It has been observed that it also occurs on the order of nm.

Therefore, although it cannot be clearly concluded, it is considered that the hydrophilization phenomenon by the photo-semiconductor is a phenomenon which is slightly different from the photodecomposition of the substance by the photocatalytic redox reaction. However, it was confirmed that the surface is not hydrophilized unless the light having an energy higher than the band gap energy of the optical semiconductor is irradiated. Possibly, polarity is applied to the surface of the optical semiconductor-containing layer by the generated conduction electrons and holes by the excitation of the optical semiconductor water hydroxyl (OH ^-)
It is considered that the surface is chemically adsorbed in the form of, and a physically adsorbed water layer is further formed thereon, and the surface becomes hydrophilic.

Once the surface of the photo-semiconductor-containing layer has been made highly hydrophilic by photoexcitation, even if the substrate is kept in a dark place,
The hydrophilicity of the surface lasts for some time. When contaminants are adsorbed on the surface hydroxyl groups with the lapse of time and the surface gradually loses hydrophilicity, hydrophilicity is restored by photoexcitation again.

To initially hydrophilize the photosemiconductor-containing layer, any light source having a wavelength of energy higher than the bandgap energy of the photosemiconductor can be utilized. In the case of an optical semiconductor in which the photoexcitation wavelength is located in the ultraviolet region such as titania, under the condition that sunlight hits the substrate coated with the optical semiconductor-containing layer, the ultraviolet rays contained in the sunlight are preferably used. be able to. An optical semiconductor can be optically excited by an artificial light source indoors or at night. As will be described later, when the optical-semiconductor-containing layer is made of silica-containing titania, it can be easily made hydrophilic even with weak ultraviolet rays contained in a fluorescent lamp.

After the surface of the photosemiconductor-containing layer is once made hydrophilic, the hydrophilicity can be maintained or restored by relatively weak light. For example, in the case of titania, the hydrophilicity can be sufficiently maintained and restored even with weak ultraviolet rays contained in an interior illumination lamp such as a fluorescent lamp.

The photo-semiconductor-containing layer exhibits hydrophilicity even if it is very thin, and in particular, the photo-catalytic semiconductor material made of a metal oxide has a sufficient hardness, so that the photo-semiconductor-containing layer has a sufficient durability and abrasion resistance. Have.

Substrate In the present invention, the substrate includes, for example, metal, ceramics, glass, plastics, wood, stone, cement, concrete, combinations thereof, laminates thereof, and coating to them. The surface of the base material is covered with the optical semiconductor-containing layer.

When the base material is made of a non-heat resistant material such as plastics or when the base material is coated with a paint, a photo-oxidation resistant paint containing an optical semiconductor is used as described later. The optical semiconductor-containing layer can be formed by applying it to the surface and curing it.

Examples of the optical semiconductor used in the optical semiconductor present invention, titania (TiO ₂₎ is most preferred. Titania is harmless, chemically stable, and available at low cost. Furthermore, since titania has a high band gap energy and therefore requires ultraviolet light for photoexcitation and does not absorb visible light in the process of photoexcitation, color development by a complementary color component does not occur.

As titania, both anatase and rutile can be used. The advantage of the anatase type titania is that a sol in which very fine particles are dispersed can be easily obtained on the market, and a very thin thin film can be easily formed. Rutile-type titania has a lower conduction band level than anatase-type titania, but can be used for the purpose of hydrophilization by an optical semiconductor. The substrate coated with the optical semiconductor-containing layer made of titania, the titania photoexcited by UV light, water is a hydroxyl group (OH ^-) are chemisorbed on the surface in the form of, formed more physically adsorbed water layer thereon, As a result, it is considered that the surface becomes hydrophilic.

Other photo-semiconductors usable in the present invention include ZnO, SnO ₂ , SrTiO ₃ , WO ₃ and Bi _2.
There are metal oxides such as O ₃ and Fe ₂ O ₃ . It is considered that these metal oxides are likely to adsorb the surface hydroxyl group (OH ⁻ ) because the metal element and oxygen are present on the surface similarly to titania. Also, particles of an optical semiconductor may be mixed with a metal oxide that is not an optical semiconductor, such as silica. In particular, when an optical semiconductor is mixed with silica or tin oxide, the surface can be highly hydrophilized.

As an example of the method for producing an optical semiconductor layer made of such titania containing silica, a precursor of amorphous silica (eg, tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetrabutoxysilane, tetra A mixture of tetraalkoxysilane such as methoxysilane; silanol which is a hydrolyzate thereof; or polysiloxane having an average molecular weight of 3,000 or less) and crystalline titania sol is applied to the surface of the substrate, and hydrolyzed as necessary. After decomposing to form silanol, the silanol is subjected to dehydration polycondensation by heating at room temperature or if necessary, to form an optical semiconductor layer in which titania is bound with amorphous silica.

Shape of photocatalyst layer by firing of amorphous titania
Light forming substrate is a metal, ceramic, if it is formed of a heat resistant material such as glass, which is excellent in wear resistance exhibiting a high degree of hydrophilicity to the extent that the contact angle with water becomes 0 ° One of the preferred ways of forming the semiconductor-containing layer 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. Any of the following methods can be adopted for forming amorphous titania.

(1) Hydrolysis and Dehydration Polycondensation of Organic Titanium Compounds Titanium alkoxides such as tetraethoxy titanium, tetraisopropoxy titanium, tetra n-propoxy titanium, tetrabutoxy titanium, tetramethoxy titanium, hydrochloric acid or ethyl amine. After adding such a hydrolysis inhibitor and diluting it with an alcohol such as ethanol or propanol, the mixture is spray-coated, flow-coated, while the hydrolysis is partially or completely allowed to proceed. Spin coating,
Apply dip coating, roll coating, or other coating method to the surface of the substrate, and
Dry at a temperature of 00 ° C. Drying completes the hydrolysis of titanium alkoxide to produce titanium hydroxide,
A layer of amorphous titania is formed on the surface of the substrate by dehydration polycondensation of titanium hydroxide. Instead of titanium alkoxide, other organotitanium compounds such as titanium chelate or titanium acetate may be used.

(2) Formation of amorphous titania from an inorganic titanium compound An inorganic titanium compound such as TiCl ₄ or Ti (SO
₄ ) Apply the acidic aqueous solution of ₂ to the surface of the substrate by spray coating, flow coating, spin coating, dip coating, or roll coating. Then, the inorganic titanium compound is subjected to hydrolysis and dehydration polycondensation by drying at a temperature of about 100 to 200 ° C. to form a layer of amorphous titania on the surface of the substrate. Alternatively, amorphous titania may be applied to the surface of the substrate by chemical vapor deposition of TiCl ₄ .

(3) Formation of amorphous titania by sputtering Amorphous titania is deposited on the surface of a substrate by irradiating a target of metallic titanium or TiO ₂ with an electron beam in an oxidizing atmosphere.

(4) Firing Temperature Amorphous titania is fired at a temperature of at least the crystallization temperature of anatase. By firing at a temperature of 400 to 500 ° C. or higher, amorphous titania can be converted to anatase type titania. By firing at a temperature of 600 to 700 ° C. or higher, amorphous titania can be converted to rutile type titania.

Photocatalyst layer composed of silica-containing titania Another preferable method for forming a photo-semiconductor-containing layer having a high degree of hydrophilicity such that the contact angle with water is 0 ° and excellent in abrasion resistance is titania and silica. Is to form an optical semiconductor-containing layer made of a mixture thereof with the surface of the base material. The ratio of silica to the total of titania and silica is 5-90.
Mol%, preferably 10 to 70 mol%, more preferably 10 to 50 mol%. Any of the following methods can be adopted to form the optical semiconductor-containing layer made of silica-containing titania.

(1) A suspension containing particles of anatase-type or rutile-type titania and silica particles is applied to the surface of a base material and sintered at a temperature below the softening point of the base material. (2) Amorphous silica precursor (for example, tetraalkoxysilane such as tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetrabutoxysilane, tetramethoxysilane, etc .; silanol which is a hydrolyzate thereof; Alternatively, a mixture of polysiloxane having an average molecular weight of 3,000 or less) and crystalline titania sol is applied to the surface of the base material, and if necessary, hydrolyzed to form silanol, and then heated at a temperature of about 100 ° C. or higher. By subjecting silanol to dehydration polycondensation, an optical semiconductor-containing layer in which titania is bound with amorphous silica is formed.
In particular, when the dehydration condensation polymerization temperature of silanol is carried out at a temperature of about 200 ° C. or higher, the degree of polymerization of silanol can be increased and the alkali resistance performance of the photosemiconductor-containing layer can be improved.

(3) Amorphous titania precursor (organic titanium compound such as titanium alkoxide, chelate or acetate, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) is added to a solution of silica. Amorphous titania thin film in which silica particles are dispersed by applying a suspension of particles dispersed on the surface of a substrate and subjecting a titanium compound to hydrolysis and dehydration polycondensation at a temperature from room temperature to 200 ° C. To form. Then, the amorphous titania is phase-changed into crystalline titania by heating the titania to a temperature above the crystallization temperature and below the softening point of the substrate.

(4) Amorphous in a solution of a precursor of amorphous titania (organic titanium compound such as titanium alkoxide, chelate or acetate, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ). Precursors of silica (eg, tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetrabutoxysilane, tetramethoxysilane, and other tetraalkoxysilanes; silanols that are hydrolysates thereof; or average molecular weight 3, 000 or less polysiloxane) is mixed and applied to the surface of the base material. Then, these precursors are subjected to hydrolysis and dehydration polycondensation to form a thin film composed of a mixture of amorphous titania and amorphous silica. Then, the amorphous titania is phase-changed into crystalline titania by heating the titania to a temperature above the crystallization temperature and below the softening point of the substrate.

Still another preferred method for forming a photo-semiconductor-containing layer having a high degree of hydrophilicity such that the contact angle with water of the photo-semiconductor layer made of titania containing tin oxide is 0 ° is excellent. That is, an optical semiconductor-containing layer made of a mixture of titania and tin oxide is formed on the surface of the base material. The ratio of tin oxide to the total of titania and tin oxide is 1 to
It can be 95% by weight, preferably 1 to 50% by weight. Any of the following methods can be adopted for forming the optical semiconductor-containing layer made of tin oxide-containing titania.

(1) A suspension containing particles of anatase type or rutile type titania and tin oxide particles is applied to the surface of a base material and sintered at a temperature below the softening point of the base material. (2) Tin oxide particles are added to a solution of an amorphous titania precursor (organic titanium compound such as titanium alkoxide, chelate, or acetate, or an inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ). Apply the dispersed suspension to the surface of the base material and apply the titanium compound from room temperature to 2
By subjecting to hydrolysis and dehydration polycondensation at a temperature of 00 ° C., a thin film of amorphous titania in which tin oxide particles are dispersed is formed. Then, the amorphous titania is phase-changed into crystalline titania by heating the titania to a temperature above the crystallization temperature and below the softening point of the substrate.

Still another preferred method of forming a photosemiconductor layer exhibiting a high degree of hydrophilicity such that the contact angle with water of the silicone paint containing the photosemiconductor is 0 ° is uncured or partially cured silicone ( It is to use a composition in which photo-semiconductor particles are dispersed in a film-forming element composed of an organopolysiloxane) or a silicone precursor. When this composition is applied to the surface of a base material and the film-forming element is cured, and then the photo-semiconductor is photoexcited, the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by the action of the photo-semiconductor, The surface of the semiconductor-containing layer is made hydrophilic.

There are several advantages to this approach. Since the photo-semiconductor-containing silicone coating can be cured at room temperature or a relatively low temperature, it can be applied to non-heat resistant materials such as plastics and organic materials. This coating composition containing an optical semiconductor can be applied to an existing base material whose surface needs to be hydrophilized by dipping, brush coating, spray coating, roll coating or the like at any time, if necessary. Hydrophilization of an optical semiconductor by photoexcitation can be easily performed with a light source such as sunlight.

Furthermore, when a coating film is formed on a plastically workable base material such as a steel plate, it is possible to easily plastically process the steel plate as necessary after curing the coating film and before photoexcitation. it can. Before photo-excitation, the organic group is bonded to the silicon atom of the silicone molecule, so the coating film has sufficient flexibility, so it is possible to easily plastically process the steel sheet without damaging the coating film. You can After the plastic working, when the photo-semiconductor is photoexcited, the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by the photo-semiconductor action, and the surface of the coating film is made hydrophilic.

Since the photo-semiconductor-containing silicone composition has a siloxane bond, it has sufficient resistance to the photo-oxidation action of the photo-semiconductor (photo-semiconductor). Still another advantage of the photo-semiconductor-containing layer made of a photo-semiconductor-containing silicone coating is that after the surface is once hydrophilized, the photo-semiconductor-containing layer maintains hydrophilicity for a long period of time even if kept in a dark place, and it has a property like a fluorescent lamp. It is to recover the hydrophilicity even with the light of the interior lighting.

As the film forming element, methyltrichlorosilane, methyltribromosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltri-t-butoxysilane; ethyltrichlorosilane, ethyltribromosilane, Ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, ethyltri-t-butoxysilane; n-propyltrichlorosilane, n-propyltribromosilane, n-propyltrimethoxysilane,
n-propyltriethoxysilane, n-propyltriisopropoxysilane, n-propyltri-t-butoxysilane; n-hexyltrichlorosilane, n-hexyltribromosilane, n-hexyltrimethoxysilane, n
-Hexyltriethoxysilane, n-hexyltriisopropoxysilane, n-hexyltrit-butoxysilane; n-decyltrichlorosilane, n-decyltribromosilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n -Decyltriisopropoxysilane, n-decyltri-t-butoxysilane; n-octadecyltrichlorosilane, n-octadecyltribromosilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octadecyltriisopropoxysilane, n-octadecyltri-t-butoxysilane; phenyltrichlorosilane, phenyltribromosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltrisilane -Butoxysilane; tetrachlorosilane, tetrabromosilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane; dimethyldichlorosilane, dimethyldibromosilane, dimethyldimethoxysilane, dimethyldiethoxysilane; diphenyldisilane Chlorosilane, diphenyldibromosilane, diphenyldimethoxysilane,
Diphenyldiethoxysilane; phenylmethyldichlorosilane, phenylmethyldibromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane; trichlorohydrosilane, tribromohydrosilane, trimethoxyhydrosilane, triethoxyhydrosilane, triisopropoxyhydrosilane, tri-t -Butoxyhydrosilane; vinyltrichlorosilane, vinyltribromosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane,
Vinyltri-t-butoxysilane; trifluoropropyltrichlorosilane, trifluoropropyltribromosilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, trifluoropropyltriisopropoxysilane, trifluoropropyltrit-butoxysilane; γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxy Silane, γ-glycidoxypropyltri-t-butoxysilane; γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryl Riloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-methacryloxypropyltri-t-butoxysilane; γ-aminopropylmethyldimethoxysilane, γ- Aminopropylmethyldiethoxysilane, γ
-Aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropyltri-t-butoxysilane; γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane , Γ-mercaptopropyltrimethoxysilane, γ-
Mercaptopropyltriethoxysilane, γ-mercaptopropyltriisopropoxysilane, γ-mercaptopropyltri-t-butoxysilane; β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β-
(3,4-epoxycyclohexyl) ethyltriethoxysilane; and their partial hydrolysates; and mixtures thereof can be used.

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

Addition of antibacterial enhancer The photo-semiconductor-containing layer can be doped with a metal such as Ag, Cu or Zn. In order to dope an optical semiconductor with Ag, Cu, or Zn, soluble salts of these metals are added to a suspension of optical semiconductor particles, and the resulting solution is used to form an optical semiconductor-containing layer. it can. Alternatively, after forming the photo-semiconductor-containing layer, soluble salts of these metals may be applied and photo-reduced to be precipitated by light irradiation.

The photo-semiconductor-containing layer doped with Ag, Cu, or Zn can kill bacteria adhering to the surface. Further, this optical semiconductor-containing layer is a mold, algae,
Inhibits the growth of moss-like microorganisms. Therefore, the surface of the member can be kept clean for a long period of time.

[0041] doped optical semiconductor-containing layer of the optical activity enhancer further, Pt, Pd, Rh, R
It can be doped with platinum group metals such as u, Os, Ir. Similarly, these metals can be doped into the optical semiconductor by photoreduction precipitation or addition of a soluble salt. When the optical semiconductor is doped with a platinum group metal, the redox activity of the optical semiconductor can be enhanced, and contaminants attached to the surface can be decomposed.

Photoexcitation / Ultraviolet Irradiation In the present invention, it is preferable that the optical semiconductor-containing layer is formed of an optical semiconductor such as titania which has a high band gap energy and is photoexcited only by ultraviolet rays. By doing so, visible light is not absorbed by the optical semiconductor-containing layer, and the member does not develop color due to the complementary color component. Anatase-type titania can be photoexcited with ultraviolet rays having a wavelength of 387 nm or less, rutile-type titania of 431 nm or less, tin oxide of 344 nm or less, and zinc oxide of 387 nm or less.

As the ultraviolet light source, a fluorescent lamp, an incandescent lamp,
Interior lighting such as metal halide lamps and mercury lamps can be used. Under the conditions of exposure to sunlight, the photosemiconductor is naturally spontaneously photoexcited by the ultraviolet rays contained in sunlight.

Photoexcitation has a contact angle with water on the surface of about 10 °.
The following can be performed or can be performed until the temperature is preferably about 5 ° or less, particularly about 0 °. In general, 0.00
Photoexcitation with an ultraviolet illuminance of 1 mW / cm ² can make hydrophilic until the contact angle with water becomes about 0 ° in a few days. The illuminance of ultraviolet rays contained in the sunlight pouring on the surface of the earth is about 0.1
Since it is 1 mW / cm ² , the surface can be made hydrophilic in a shorter time by exposing it to sunlight.

When the photo-semiconductor-containing layer is formed of titania-containing silicone, the photocatalyst is photoexcited with sufficient illuminance so that the surface organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group in a sufficient amount. Is preferred.
The most advantageous way to do this is to use sunlight. Once the surface is highly hydrophilized, the hydrophilicity persists at night. Each time it is exposed to sunlight again, the hydrophilicity is restored and maintained.

When the member of the present invention is provided to the user, it is desirable to hydrophilize the member in advance.

In the present invention, an intermediate layer may be provided between the base material and the photosemiconductor-containing layer. This increases the adhesion to the base material and improves the wear resistance.

[0048]

EXAMPLES Examples of the present invention will be described. Example 1 A surface layer consisting of 70 parts of anatase type titanium oxide, 30 parts of silica and 1 part of platinum was formed on a substrate tile by the following method. First, anatase type titania sol (Ishihara Sangyo of Osaka, STS-11), colloidal silica sol (Nissan Kagaku, Snowtex O) and chloroplatinic acid hexahydrate are mixed, and a 15 cm square glazed tile (Totoki, AB02E0).
Apply to the surface of 1) by spray coating method, and
The sample was baked at a temperature of 00 ° C. for 1 hour to obtain a sample coated with a film made of titania and silica. Film thickness is 0.5μ
It was m. 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 is still 5
°. 0.0 on the surface of the sample using a BLB fluorescent lamp
When ultraviolet rays were irradiated for 1 day at an ultraviolet illuminance of 3 mW / cm ² , the contact angle with water became 0 °.

Example 2 A surface layer consisting of 50 parts of anatase type titanium oxide, 50 parts of silica and 1 part of palladium was formed on a substrate tile by the following method. A mixture of TiO ₂ (TA-15, Nissan Chemical Co., Ltd.), tetraethoxysilane and an aqueous solution of palladium chloride was applied on the surface of a glazed tile having a 15 cm square and heated at 150 ° C. to obtain a sample. The film thickness of the coating was 0.5 μm. After the sample was left in the dark for 1 week and irradiated with a BLB lamp of 0.03 mW / cm ² , the contact angle with water was 0 °.

Comparative Example The tile described above was used as is.

Evaluation of Contact Angle with Water Next, this sample was irradiated with ultraviolet rays for 1 day using a BLB fluorescent lamp at an illuminance of 0.5 mW / cm ² . The contact angle of the surface of this sample with water was measured with a contact angle measuring device (CA-X150). In Examples 1 and 2, the contact angle was 0 °. On the other hand, the contact angle of the comparative example was 30 °.

Oleic acid in water release test The surface of the samples of Examples and Comparative Examples was coated with oleic acid,
While holding the sample surface in a horizontal position, each sample was immersed in water filled in a water tank. In the comparative sample, oleic acid remained attached to the surface of the sample. On the other hand, in the sample of the example, the oleic acid rolled up into an oil droplet, which was released from the surface of the sample and floated. Thus, when the surface of the base material is covered with the photocatalytic top coat, the surface of the base material is kept hydrophilic, and oily stains can be easily released from the surface in water to clean the surface. confirmed. In this embodiment, for example, if a photo-semiconductor coating is provided on the surface of a member and the photo-semiconductor is excited by ultraviolet rays, the member surface soiled with oil can be easily cleaned by flushing it with water without using a detergent. Shows.

After application of trioleic acid glyceride BLB illumination
Morphism trioleate glycerides 2.5mg applied to the substrate surface, by measurement of weight loss after irradiation 1 week BLB lamp 0.5 mW / cm ² at 70% humidity, in Examples Samples 1 and 2 Reduced by 2.5 mg. It is considered that the applied trioleic acid glyceride was completely decomposed into CO ₂ and H ₂ O. On the other hand, in Comparative Example, almost no weight reduction was observed.

[0054]

As is apparent from the above description, the present invention can provide an antifouling plate that easily removes oil stains and the like attached thereto. Furthermore, it is possible to provide an antifouling plate that also has a function of decomposing adhered oil stains and the like.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B32B 27/18 B32B 27/18 Z 27/30 27/30 D // C08J 7/04 C08J 7 / 04 T (72) Inventor Eiichi Kojima 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture Totoki Equipment Co., Ltd. (72) Toshiya Watanabe 2-1-1 Nakajima, Kitakyushu, Kitakyushu, Fukuoka In Totoki Co., Ltd. (72) Inventor Atsushi Kitamura 2-1, 1-1 Nakajima, Kokurakita-ku, Kitakyushu, Fukuoka Prefecture In Totoki Co., Ltd. (72) Inventor Makoto Senkoku, Nakajima, Kitakyushu, Kitakyushu, Fukuoka 1st-1st Totoki Equipment Co., Ltd.

Claims (8)

[Claims] 1. An antifouling plate, which is arranged around a device that causes dirt emission and receives the dirt; a surface layer containing an optical semiconductor, the surface of which is hydrophilic in response to photoexcitation of the optical semiconductor. Antifouling plate characterized by exhibiting properties. 2. The antifouling plate according to claim 1, wherein the photosemiconductor oxidizes and decomposes stains attached to the antifouling plate by its photooxidation effect. 3. The antifouling plate according to claim 1, wherein the surface layer containing the optical semiconductor contains anatase type titanium oxide and silica. 4. The antifouling plate according to claim 1, wherein the surface layer containing the optical semiconductor contains anatase type titanium oxide and at least a part of silanolized silicone. 5. The surface layer further comprises Ag, Pt, Pd,
1 or 2 selected from the group consisting of Ru, Os, and Ir
The antifouling plate according to claim 3 or 4, including the above. 6. The antifouling plate according to claim 1, wherein the surface layer further contains an antibacterial metal. 7. The antifouling plate is a kitchen bag arranged around a stove in a kitchen.
Antifouling plate as described in the item. 8. The antifouling plate according to claim 1, wherein a base material of the antifouling plate is made of a heat-resistant material such as ceramics, metal, silicone resin, and fluororesin.