JP2003010696A - Photocatalyst body and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a photocatalyst body constituted by uniformly and strongly bonding a photocatalyst layer to a substrate and excellent in scratch resistance and weatherability, and to provide a method for manufacturing the same. SOLUTION: A hydrophobic and/or water-repellent silicone resin coating material is applied to at least a part of the surface of the substrate and the obtained film surface is irradiated with ultraviolet rays with a wavelength of 185 nm or less to be subjected to hydrophilizing treatment or a hydrophilic silicone resin coating material is applied to the surface of the substrate to form a hydrophilic silicone resin layer comprising a silicone resin film of which the contact angle with water is not more than 20 deg. and, thereafter the resin layer is coated with an aqueous photocatalyst coating agent containing photocatalyst particles and a metal oxide binder to obtain the photocatalyst layer, which is, in turn, heated or irradiated with ultraviolet rays to manufacture the photocatalyst body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst body having a photocatalyst layer firmly adhered to a substrate and excellent in scratch resistance and weather resistance, and a method for producing the same.

[0002]

2. Description of the Related Art Anatase-type titanium oxide having a photocatalytic function is activated by being irradiated with ultraviolet rays, and oxidatively decomposes organic substances and the like by the active oxygen generated on the surface, or the surface is hydrophilized to prevent stains. Demonstrate functions such as anti-fog.
2. Description of the Related Art In recent years, there is a need for environmentally cleanable products having functions such as antibacterial, deodorant, and antifouling due to pollution countermeasures and an increase in health, comfort, and cleanliness, and products using photocatalysts have attracted attention. For example, photocatalysts are used outdoors for anti-fouling treatments such as oil, inorganic dust, and carbon, which are the main components of urban pollution, for anti-fog treatment to ensure visibility, and for indoor use, antibacterial and deodorant. It can be widely used for sanitary treatment.

By the way, particles having a photocatalytic function such as anatase type titanium oxide (hereinafter referred to as photocatalytic particles) have poor film-forming property by themselves, and therefore, for example, a photocatalyst coating agent is usually hydrolyzed with an alkoxysilane. A silica-based binder or silicone-based resin binder derived from a decomposed product is mixed to increase film-forming properties,
A method has been proposed in which a photocatalyst is coated and fixed as a transparent film that can be applied to the surface of a base material such as metal, ceramics, or wood to maintain the design (Japanese Patent Application Laid-Open No. 7-171408, etc.).

However, since the main solvent of the coating agent is an organic solvent, the coating film during coating is difficult to level and it is difficult to form a uniform transparent film unless the temperature and humidity during coating operation are controlled. . Moreover, since an acid may be added to the coating agent, the load on the equipment is large. Further, there is a problem that the storage stability is as short as a few months in a cool and dark place. Therefore, it is desired to switch to an aqueous coating agent in consideration of workability and environment.

In the preparation of an aqueous photocatalytic coating agent, for example, when amorphous titanium oxide derived from orthotitanic acid or peroxotitanic acid or amorphous silica derived from an aqueous silicate is used as a binder (Japanese Patent Laid-Open No. 9-262481). ), No organic solvent, p
Not only can an aqueous solution in which H is in the neutral region be used, but further long-term storage of at least six months at room temperature can be stably achieved, which has the advantages of improved workability and easier handling.

However, when the water-based photocatalyst coating agent is uniformly applied to the substrate, if the substrate surface is hydrophobic, there is a problem that the coating agent is repelled and the photocatalyst layer cannot be formed. Therefore, in order to uniformly apply the aqueous photocatalyst coating agent to the substrate, it is preferable to make the surface of the substrate hydrophilic at a contact angle of water of 20 ° or less, and as the binder layer of the photocatalyst layer as in the present invention. When the silicone resin coating is provided on the surface of the base material, it is necessary to make the surface of the silicone resin coating hydrophilic.

As a method of hydrophilizing a silicone resin coating, a silicone resin containing 80% by mass or more of a hydrolyzate of a tetrafunctional alkoxysilane in order to arrange a large number of hydroxyl groups on the surface of the resin is applied, or a hydrophobic resin is used. Alternatively, there is a method of hydrophilizing the surface of the water-repellent silicone resin by a dry method. As a method for making hydrophilic by a dry method, for example, a method in which a surface of a hydrophobic or water-repellent silicone resin is subjected to a corona treatment, a plasma discharge treatment, or an ultraviolet irradiation treatment has been proposed (Japanese Patent Laid-Open No. 2000-109580). Among them, ultraviolet irradiation has an advantage that a large area or a substrate having a different shape, and further, both surfaces can be simultaneously processed. However, irradiation with a germicidal lamp (wavelength 254 nm) as disclosed in the publication, Hydrophilicity of silicone resin is slow and not practical.

The surface of the hydrophilic silicone resin is used alone for the purpose of antifouling. However, if oil such as exhaust gas, which is the main component of urban pollution, adheres to the surface, the hydrophilicity is reduced. However, there is a problem with the sustainability of the antifouling function.

[0009]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional techniques, the present invention provides a photocatalyst body having a photocatalyst layer uniformly and firmly adhered to a substrate, which is excellent in scratch resistance and weather resistance, and a method for producing the same. The purpose is to provide. In order to achieve the object, the present inventor has determined that the wettability of the surface of the silicone-based resin, which is the binder layer of the photocatalyst layer, which is the coating surface of the aqueous photocatalyst coating agent, is hydrophilic at a contact angle of water of 20 ° or less. With the aim of achieving the above, various studies have been made and the present invention has been achieved.

[0010]

According to the present invention, a contact angle between a base material and water formed on at least a part of the surface of the base material is 2 or less.
A photocatalyst body comprising a hydrophilic silicone resin layer composed of a silicone resin film of 0 ° or less and a photocatalyst layer containing photocatalyst particles and a metal oxide binder formed on the resin layer.

Further, according to the present invention, at least a part of the surface of the substrate is coated with a hydrophobic and / or water repellent silicone resin coating, and the surface of the obtained coating film is irradiated with ultraviolet rays to be subjected to a hydrophilic treatment. After forming a hydrophilic silicone resin layer composed of a silicone resin film having a contact angle with water of 20 ° or less, an aqueous photocatalyst coating agent containing photocatalyst particles and a metal oxide binder is applied onto the resin layer. And a photocatalyst layer is formed.

In the present invention, the ultraviolet rays have a wavelength of 185 nm.
It preferably contains the following ultraviolet rays.

Further, according to the present invention, a hydrophilic silicone resin layer is formed by coating a hydrophilic silicone resin coating on at least a part of the surface of a base material and comprising a silicone resin coating having a contact angle with water of 20 ° or less. After forming, on the resin layer,
A method for producing a photocatalyst body, which comprises applying a water-based photocatalyst coating agent containing photocatalyst particles and a metal oxide binder to form a photocatalyst layer.

In the present invention, it is preferable that the hydrophilic silicone resin coating material contains 80% by mass or more of a hydrolyzate of a tetrafunctional alkoxysilane.

The present invention also provides a method for producing a photocatalyst, wherein the photocatalyst layer is formed by applying the photocatalyst coating agent and then heating and / or irradiating ultraviolet rays having a wavelength of 315 nm or less. is there.

The present invention is a hydrophilic silicone resin whose main component is a hydrolyzate of a tetrafunctional alkoxysilane, or
Focusing on the fact that a hydrophilic silicone resin obtained by irradiating a hydrophobic and / or water-repellent silicone resin with ultraviolet rays shows hydrophilicity of 20 ° or less at a contact angle of water, By coating the material, the aqueous photocatalyst coating agent can be directly and uniformly coated, and the photocatalyst layer is firmly adhered to the substrate by using the hydrophilic silicone-based resin layer as a binding layer. It was done.

Further, according to the present invention, a hydroxyl group (M-OH: M is a metal element) and a peroxo group (M-O-O- :) are irradiated by irradiating ultraviolet rays having a wavelength of 315 nm or less (far ultraviolet rays and vacuum ultraviolet rays). M is a metallic element) is activated,
Focusing on the fact that the condensation reaction is promoted, by irradiating the photocatalyst layer with the ultraviolet rays, the photocatalyst layer is densified, and further, at the interface between the photocatalyst layer and the silicone resin layer, a residual hydroxyl group, a peroxo group, Since the alkoxy group is activated to form a chemical bond, it is dense and hard that can withstand outdoor use even for resin substrates with low heat resistance,
The photocatalyst layer excellent in scratch resistance and firmly adhered to the base material is formed in a short time.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION [Substrate] The substrate used in the present invention includes inorganic materials such as ceramics, tiles, concrete, glass and bricks, aluminum, stainless steel plates,
Metal materials such as plated steel sheets, chemical conversion treated steel sheets, painted steel sheets,
Resins such as acrylic resin and polycarbonate resin, organic materials such as wood, etc., are not particularly limited to these. The shape of the substrate is a block, a plate (sheet), a film, a structure, an article, etc., but is not particularly limited thereto. The size and thickness of the base material are not particularly limited.

[Silicone-based resin] The hydrophilic silicone-based resin used in the present invention is a silicone-based resin having 80% by mass or more of a siloxane molecular structural unit of a tetrafunctional alkoxysilane, and a polymer-dispersed silica. The hydrophobic and water-repellent silicone resin is a silicone resin or an organic-inorganic hybrid resin other than the hydrophilic silicone resin described above, but is not particularly limited thereto.

The silicone resin is a polymer of hydrolyzable monomer represented by the following structural formula. X _n Si (OR) _4-n X is a modified alkyl group into which an alkyl group such as a methyl group or a phenyl group or an organic functional group represented by a γ-glycidoxyalkyl group is introduced. The X's of the monomers may be the same or different.

The introduction of the modified alkyl group plays a role of reacting with or compatibilizing the organic resin of the base material. For example, alkyd modification is flexibility and dryness, epoxy modification is chemical resistance and adhesion, and acrylic modification is The toughness and polyester modification impart flexibility and gloss to the silicone resin, and can be appropriately selected depending on the purpose.

OR is a hydrolyzable alkoxy group having 1 to 8 carbon atoms. The alkoxy group is hydrolyzed to a hydroxyl group, and a polymer is formed by dealcoholation reaction and dehydration reaction. n is an integer of 0-3. The hardness of the silicone resin is expressed by the siloxane molecular structural unit of tetrafunctional alkoxysilane, and the flexibility is imparted by the siloxane molecular structural unit of difunctional trifunctional alkoxysilane.

Usually, the silicone resin belongs to hydrophobic and water-repellent silicone resins, but exhibits hydrophilicity by arranging a large number of hydroxyl groups (Si-OH) on the resin surface. For example, the silicone resin component may be blended in an amount of 80% by mass or more, preferably 90% by mass or more based on the siloxane molecular structural unit of a tetrafunctional alkoxysilane.

The polymer-dispersed silica is one in which an organic polymer such as polyethylene glycol is dispersed in a silicone resin matrix whose main component is the siloxane molecular structural unit of the above-mentioned tetrafunctional alkoxysilane to impart flexibility. , Belongs to hydrophilic silicone resin.

The organic-inorganic hybrid resin is a copolymer of the above silicone resin and an organic resin, a copolymer of an aqueous silicate and an aqueous organic resin, etc., and belongs to a hydrophobic or water repellent silicone resin. For example, the former is a copolymer in which an organic resin introduced with an alkoxysilyl group is crosslinked with a silicone resin through an alkoxysilane having an alkoxy group as a functional side chain.

The silicone resin is usually made into a paint by dispersing an alkoxysilane polymer or a copolymer of an alkoxysilane polymer and an organic resin in a solvent, and the solid content is appropriately within the range of 1 to 50% by mass. To be selected. As a solvent for the paint, organic solvents such as alcohols, ketones and esters are generally used, but in the case of an organic-inorganic hybrid resin, an aqueous emulsion paint can also be used. For example,
It can be synthesized by dissolving a silicone resin having a silanol group in a radically polymerizable vinyl monomer and emulsion-polymerizing it in the presence of a surfactant. The molecular weight of the silicone resin is 200 to 2 in terms of polystyrene equivalent weight average molecular weight.
It is 0000, and preferably 500 to 5000, but is not particularly limited.

An alkoxysilane having an alkoxy group having a functional side chain as a cross-linking agent, a metal-containing organic compound such as Zn, Al, Sn, Co and Zr as a curing agent, a boron halide compound and the like are added to a silicone resin coating material. You may. Inorganic oxide particles such as silica sol and alumina sol may be blended as a filler in the silicone resin coating, and a surfactant and silica sol may be blended as an antistatic agent.

When the adhesion between the silicone resin layer and the base material is poor, as shown in FIG. 2, a primer layer 5 is provided on the surface of the base material 2, or the surface of the base material 2 is subjected to plasma discharge, corona treatment, or the like. It is preferable to perform an ultraviolet treatment including a wavelength of 185 nm or less. In consideration of compatibility with the base material, the primer is appropriately selected and used from primers having an acrylic resin, an epoxy resin, an acrylic silicone resin or the like as a main component.

[Photocatalyst] The photocatalyst layer of the present invention is a layer formed on the surface of a silicone resin layer and containing photocatalyst particles and a metal oxide binder, and has a layer thickness of 0.05 μm.
The above is preferably 0.05 to 1.0 μm. The photocatalyst used in the present invention may be any photocatalyst as long as it produces active oxygen by receiving light and exhibits photoactivity.
O ₂ , ZnO, Fe ₂ O ₃ , WO ₃ , SnO ₂ , Bi ₂
Metal oxides such as O ₃ , SrTiO ₃ and FeTiO ₃ ,
GaP, CdS, CdSe, GaAs, MoS ₂ , Zn
A metal compound such as S is exemplified. Preferred is anatase type titanium oxide.

The average particle size of the photocatalyst particles is 5 to 200 nm, preferably 10 to 100 nm. If it is less than 5 nm, the band gap increases due to the quantum size effect.
If it exceeds 00 nm, the transparency of the photocatalyst layer and the dispersibility in the photocatalyst coating agent decrease. Average particle size is 10-100n
To obtain the photocatalytic particles of m, a sol solution of anatase type titanium oxide can be used. For example, a solution containing a hydrolyzate of orthotitanic acid, peroxotitanic acid, titanium alkoxide, etc. is heat-treated at 80 ° C. or higher, or an aqueous solution of titanium salt such as titanium sulfate is heated to 110 to 200 ° C. using a pressure device such as an autoclave. It can be obtained by hydrothermal treatment with, but is not particularly limited thereto.

Metal oxide binders include, but are not limited to, amorphous titanium oxide, amorphous silica, or mixtures thereof. The aqueous solution of amorphous titanium oxide is, but not limited to, orthotitanic acid, hydrolyzate of peroxotitanic acid or titanium alkoxide, or a mixture thereof. Orthotitanic acid can be obtained by hydrolyzing and dialyzing an aqueous solution of a titanium salt such as titanium sulfate. Peroxotitanic acid can be obtained by treating titanium chloride with aqueous ammonia or by hydrolyzing titanium alkoxide to dissolve titanium hydroxide in aqueous hydrogen peroxide. Of the titania-based binders, peroxotitanic acid is preferable because it has a high affinity with the hydroxyl group of the silicone-based resin and is excellent in film-forming property. Aqueous solutions of amorphous silica include, but are not limited to, alkali silicates, polymeric compounds derived from quaternary ammonium silicates, or mixtures thereof.

The aqueous photocatalyst coating agent can be prepared, for example, by mixing an anatase type titanium oxide sol solution and a metal oxide binder at an arbitrary ratio. When the solid content concentration of the aqueous photocatalyst coating agent is 10% by mass or less, preferably 5% by mass or less, an interference film and a thin film of a photocatalyst layer without cracks can be formed.

When it is desired to improve antireflection, hydrophilicity and antistatic properties of the photocatalyst layer, an aqueous photocatalyst coating agent is added.
It is advisable to add silica. As the silica, colloidal silica can be used, and silicic acid anhydride containing few impurities is preferable, but the particle size and shape are not particularly limited.
When it is necessary to improve the wettability of the coating agent with respect to the silicone-based resin layer, the coating agent is added with 5
You may mix | blend a mass% or more, preferably 10-30 mass% alcohol.

As the alcohol, methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, s-butanol, t-butanol, ethylene glycol, polyethylene glycol,
Examples thereof include polyvinyl alcohol and glycerin, but are not particularly limited as long as they can stably exist in the photocatalyst coating agent.

[Method for Producing Photocatalyst] The photocatalyst 1 of the present invention has the structure shown in FIGS. 1 and 2, and at least a part of the surface of the substrate 2 is coated with a hydrophobic and / or water-repellent silicone resin coating. Coating to form a hydrophobic and / or water-repellent silicone resin coating, irradiating the semi-cured or completely cured coating with UV light to make it hydrophilic, and a silicone-based silicone having a contact angle with water of 20 ° or less. Forming the photocatalyst layer 4 by modifying the hydrophilic silicone-based resin layer 3 composed of a resin film, and then applying an aqueous photocatalyst coating agent containing photocatalyst particles and a metal oxide binder onto the resin layer. Manufactured by.

Further, the photocatalyst body 1 of the present invention is prepared by separately coating a hydrophilic silicone resin coating on at least a part of the surface of the base material 1 to form a silicone resin film having a contact angle with water of 20 ° or less. After forming the hydrophilic silicone resin layer 3 consisting of the above, an aqueous photocatalytic coating agent containing photocatalyst particles and a metal oxide binder is applied onto the resin layer,
It is manufactured by forming the photocatalyst layer 4.

The silicone resin coating may be applied by any of the general methods such as dipping, rolling, spraying, and screen coating, but spray coating is preferred when the base material is irregular or large in size. . When applying,
The substrate may be heated.

The thickness of the silicone-based resin layer may be 0.05 μm or more in order to prevent the substrate from being oxidized by the photocatalyst, but when the substrate is a soft resin, the strength of the silicone-based resin layer is secured. Therefore, the thickness is preferably 1 μm or more, and more preferably 2 μm or more.

Before applying the silicone resin coating, a primer may be applied to the base material 2 to form the primer layer 5 to enhance the adhesiveness of the silicone resin. The primer is appropriately selected from resins having an acrylic resin, an epoxy resin, an acrylic emulsion resin or the like as a main component, in consideration of compatibility with the base material. The thickness of the primer layer is 0.05 μm or more, preferably 0.1 to 5 μm
m. Further, even if the surface of the substrate is subjected to plasma discharge, corona discharge treatment, or irradiation with ultraviolet rays having a wavelength of 185 nm or less to remove contaminants and introduce functional groups, the adhesiveness of the silicone resin or primer can be improved. Good.

In the case of a hydrophobic silicone-based resin or a water-repellent silicone-based resin, the resin is modified from hydrophobic or water-repellent to hydrophilic by irradiation with ultraviolet rays, and the contact angle with water is set to 20 ° or less. be able to. The ultraviolet ray to be irradiated preferably contains a wavelength of 185 nm or less. The photon energy of ultraviolet rays with wavelengths in this range is larger than the binding energy of the organic groups that make up the contaminants and the resin, and since ozone is generated as shown in the formula below, the contaminants on the surface of the silicone resin and the decomposition of the organic groups are decomposed. Along with the removal of oxygen and oxidation, silanol groups are generated and hydrophilicity is developed.

The ultraviolet light source is preferably a low-pressure mercury lamp, excimer lamp or the like, which has high intensity and good radiation efficiency. The low-pressure mercury lamp emits ultraviolet rays having wavelengths of 185 nm, and the discharge gas of Xe ₂ , Kr ₂ , and Ar ₂ excimer lamps emit ultraviolet rays having wavelengths of 172 nm, 146 nm, and 126 nm, respectively. In particular, the low-pressure mercury lamp can be easily incorporated into existing equipment, and equipment investment can be suppressed.

[0042] The irradiation time of ultraviolet rays is usually 1 to 60 minutes, preferably 1
0 to 30 minutes.

Then, an aqueous photocatalytic coating agent is applied to the surface of the hydrophilic silicone resin layer. The coating method may be any of the common methods such as dipping, rolling, spraying, and screening, but when the substrate has a irregular shape or is large, spraying is preferable. At that time, the substrate may be heated. Since the viscosity of the aqueous photocatalyst coating agent is low, atomization is possible if the air pressure of the spray gun is 98.07 kPa (1 kgf / cm ² ) or more in gauge pressure, and the silicone resin layer can be uniformly coated. it can. The thickness of the photocatalyst layer is 0.05 to 5 μm,
The thickness is preferably 0.1 to 0.5 μm so that the interference color is not noticeable.

The photocatalyst layer is improved in its densification and adhesion to the silicone resin by heat treatment and / or irradiation with ultraviolet rays. At this time, the hydroxyl group contained in the metal oxide binder of the photocatalyst layer, the peroxo group, and the hydroxyl group on the surface of the silicone-based resin are activated to cause the condensation reaction to proceed, resulting in the densification of the photocatalyst layer and the interface between the photocatalyst layer and the silicone resin. The photocatalyst layer is formed to be dense, hard, and excellent in scratch resistance, which has an increased adhesive strength at room temperature and can be used outdoors.

The heat treatment is carried out at a temperature lower than the heat resistant temperature of the base material or the silicone resin, but generally 500.
The temperature is not higher than 50 ° C., preferably 50 to 300 ° C., and the reaction time may be not shorter than 10 minutes, but these are not particularly limited.
The UV irradiation may be UV having a wavelength of 400 nm or less,
It is preferable to use far-ultraviolet rays or vacuum ultraviolet rays having a wavelength of 315 nm or less because scratch resistance is exhibited in a short time. The irradiation time is generally 1 minute or longer, preferably 5 to 30 minutes.

The ultraviolet lamp for irradiating the photocatalyst layer is preferably a sterilizing lamp having a high intensity and good radiation efficiency, a low pressure mercury lamp, an excimer lamp or the like. The sterilization lamp is 254 nm, the low-pressure mercury lamp is 185 nm, and the discharge gas is XeCl, KrCl, Xe ₂ , Kr ₂ , Ar _2.
Excimer lamps are 315nm and 222n, respectively
Ultraviolet rays having wavelengths of m, 172 nm, 146 nm and 126 nm are irradiated.

[0047]

EXAMPLES Next, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. (Example 1) Low-pressure mercury lamp (intensity of 258 nm wavelength 5
mW / cm ² and intensity of 185 nm wavelength ² mW / cm
² : Using Ushio Denki Co., Ltd., spray a hydrophobic silicone resin coating (Matsushita Electric Works, Ltd., “Fressela N”: solid content concentration 20% by mass) onto an acrylic resin plate that has been irradiated with ultraviolet rays for 10 minutes. The applied and formed resin film was dried at room temperature and then heat-treated at 80 ° C. for 30 minutes to cure the film. UV light is applied to the surface of the cured coating with the lamp.
Irradiation was carried out for 0 minutes to perform hydrophilic treatment. The contact angle of the obtained coating film with water was 10.9 °.

Next, an aqueous photocatalytic coating agent obtained by mixing anatase type titanium oxide sol and a peroxotitanic acid solution on the surface of the hydrophilic film [Tanaka Transfer Co., Ltd., "T
PX ”: solid content concentration 0.85% by mass] was applied by spraying, dried and then heated at 80 ° C. for 30 minutes to be cured to obtain a transparent photocatalyst. The film thicknesses of the silicone resin layer and the photocatalyst layer were 3 μm and 0.1 μm, respectively. The properties of the photocatalyst (boiling water resistance, scratch resistance, accelerated weathering resistance, contact angle, total transmittance / haze value) were measured and evaluated by the following methods. The results are shown in Table 1.

(Example 2) In Example 1, instead of heating the photocatalyst layer, the photocatalyst layer was cured by irradiating the photocatalyst layer with ultraviolet rays for 10 minutes using the low-pressure mercury lamp.
A transparent photocatalyst was obtained in the same manner as in Example 1. The film thicknesses of the silicone resin layer and the photocatalyst layer were 3 μm and 0.1 μm, respectively. The characteristics of the photocatalyst were measured and evaluated, and the results are shown in Table 1.

(Example 3) A hydrophilic silicone resin coating (Matsushita Electric Works, Ltd.) was applied to an acrylic resin plate irradiated with ultraviolet rays for 10 minutes with a low pressure mercury lamp (Ushio Electric Co., Ltd.).
Manufactured by "Fressela R": solid content concentration 1% by mass), and the formed resin film is dried at room temperature.
The coating was cured by heat treatment at 0 ° C. for 30 minutes. The contact angle of the obtained film with water was 18.4 °.

Then, an aqueous photocatalytic coating agent [manufactured by Tanaka Transfer Co., Ltd., "TPX": solid content concentration 0.85% by mass] was spray-coated on the surface of the resin film, and after drying, 8
It was heated at 0 ° C. for 30 minutes for curing to obtain a transparent photocatalyst. The film thicknesses of the silicone resin layer and the photocatalyst layer were 1 μm and 0.1 μm, respectively. The characteristics of the photocatalyst were measured and evaluated, and the results are shown in Table 1.

(Example 4) In Example 3, instead of heating the photocatalyst layer, the low-pressure mercury lamp was used to irradiate the photocatalyst layer with ultraviolet rays for 10 minutes to cure the photocatalyst layer.
A transparent photocatalyst was obtained in the same manner as in Example 3. The film thicknesses of the silicone resin layer and the photocatalyst layer were 1 μm and 0.1 μm, respectively. The characteristics of the photocatalyst were measured and evaluated, and the results are shown in Table 1.

(Example 5) In Example 3, an aqueous photocatalyst coating agent (manufactured by Nippon Parkerizing Co., Ltd.) in which an orthotitanic acid solution was mixed in place of the peroxotitanic acid solution which is a binder of amorphous titanium oxide,
"Paltitanium 5603": Solid content concentration 0.85% by mass]
A transparent photocatalyst was obtained by the same method as in Example 3 except that was used. The film thicknesses of the silicone resin layer and the photocatalyst layer were 1 μm and 0.1 μm, respectively. The characteristics of the photocatalyst were measured and evaluated, and the results are shown in Table 1.

(Example 6) In Example 3, instead of the peroxotitanic acid solution which is a binder of amorphous titanium oxide, an aqueous silicate solution which is a binder of amorphous silica (MS9, manufactured by Nittetsu Kenkyusho Co., Ltd.)
A transparent photocatalyst was obtained in the same manner as in Example 3 except that the aqueous photocatalyst coating agent (solid content concentration 0.85% by mass) mixed with 0) was used. The film thicknesses of the silicone resin layer and the photocatalyst layer were 1 μm and 0.1 μm, respectively. The characteristics of the photocatalyst were measured and evaluated, and the results are shown in Table 1.

(Example 7) In Example 3, a primer ("PC-7A" manufactured by Shin-Etsu Chemical Co., Ltd.) was applied in place of the acrylic resin plate irradiated with ultraviolet rays to obtain a film thickness of 0. A transparent photocatalyst was obtained in the same manner as in Example 3 except that a polycarbonate resin plate having a 5 μm primer layer was used. The film thicknesses of the silicone resin layer and the photocatalyst layer were 1 μm and 0.1 μm, respectively. The characteristics of the photocatalyst were measured and evaluated, and the results are shown in Table 1.

(Comparative Example 1) An organic-inorganic hybrid resin coating (manufactured by Nippon Soda Co., Ltd., "NRC-300") was applied to an acrylic resin plate irradiated with ultraviolet rays for 10 minutes with a low pressure mercury lamp.
A ”: solid content concentration 10% by mass) was applied by a roll coater, and the formed resin film was dried at 80 ° C. for 10 minutes. The contact angle of the obtained coating film with water was 75.0 °. Then, on the surface of the resin coating, a photocatalytic coating agent of an alcohol solvent (manufactured by Nippon Soda Co., Ltd., “NRC-3”).
00C ”: solid content concentration 2% by mass) was applied by a roll coater, dried, and then heated at 120 ° C. for 30 minutes to be cured to obtain a transparent photocatalyst. The thicknesses of the silicone resin layer and the photocatalyst layer were 1 μm and 0.2 μm, respectively. The characteristics of the photocatalyst were measured and evaluated, and the results are shown in Table 1.

(Comparative Example 2) A peroxotitanic acid solution [manufactured by Tanaka Transfer Co., Ltd., "PTA": solid content concentration 0.85% by mass] was applied to an acrylic resin plate irradiated with ultraviolet rays for 10 minutes with a low pressure mercury lamp. Then, a coating agent containing 0.5% by mass of a silicone surfactant ("KF640" manufactured by Shin-Etsu Chemical Co., Ltd.) was spray-coated to form an amorphous titanium oxide layer. Then, on the surface of the amorphous titanium oxide layer, an aqueous photocatalytic coating agent obtained by mixing anatase type titanium oxide sol and a peroxotitanic acid solution [manufactured by Tanaka Transfer Co., Ltd., "TPX": solid content concentration 0.85
Mass%] was applied by spraying, dried and then heated at 80 ° C. for 30 minutes for curing to obtain a transparent photocatalyst. The film thicknesses of the amorphous titanium oxide layer and the photocatalyst layer are each 0.
2 μm and 0.15 μm. The characteristics of the photocatalyst were measured and evaluated, and the results are shown in Table 1.

(Comparative Example 3) A hydrophobic silicone resin paint ("Fresselera N" manufactured by Matsushita Electric Works, Ltd.) was spray-coated on an acrylic resin plate irradiated with ultraviolet rays for 10 minutes with a low-pressure mercury lamp and dried. Then, the coating was cured by heat treatment at 80 ° C. for 30 minutes. The contact angle of the obtained film with water was 80.5 °. Then, on the surface of the hydrophobic coating,
An aqueous photocatalytic coating agent [manufactured by Tanaka Transfer Co., Ltd., TPX: solid content concentration 0.85% by mass] in which anatase type titanium oxide sol and a peroxotitanic acid solution were mixed was spray-applied, but the coating agent was repelled. However, the film could not be formed.

The characteristics of the photocatalyst were measured and evaluated by the following methods. (Boiling resistance) Evaluation was carried out by a cross-cut cellophane tape test (cross-cut number 100) in accordance with JIS K5400-8.20 (paint general test method). That is, the test body was immersed in boiling ion-exchanged water for 2 hours, then the appearance was observed, and a cross-cut peeling test was performed. In the cross-cut peeling test, a commercially available cellophane tape was stuck on 100 cross-cuts provided by cutting with a cutter to a depth of reaching the substrate of the test body at intervals of 1 mm, and the tape was peeled off momentarily. It was according to the method of counting the number of grids of the tape remaining on the test body after the heating.

(Scratch resistance) Specimen (100 mm × 100 m)
A load of 98.07 kPa (1 kgf / cm ² ) was applied to m) and the back surface of the sponge scrubber was rubbed 50 times in each of the length and width directions, and the appearance was visually observed and judged. The criteria for evaluation were ◯ when there were no scratches, Δ when there were 5 scratches or less, and X when there were more than 5 scratches.

(Accelerated weather resistance) Specimen (100 mm × 100
mm) using a dew panel weather meter (“DPWL-5R” manufactured by Suga Test Instruments Co., Ltd.), irradiation with an ultraviolet fluorescent tube (60 ° C., 2 hours, illuminance 30 W / m ² ) and dew condensation (50 ° C.). Cycle (2 hours, dark place) for 1000 hours. The contact angle, total light transmittance, and haze value of the test body before and after the above cycle were measured by the following methods.

(Contact angle) Specimen (100 mm x 100 mm)
And using a black light blue fluorescent tube, 0.5mW / c
After irradiating with m ² ultraviolet rays for 24 hours, 20 μl of ion-exchanged water was dropped using a microsyringe, and the water droplets on the test body were measured by an image processing contact angle meter (Kyowa Interface Science Co., Ltd., “CA
-X ") was used to measure the contact angle by the three-point method.

(Total Light Transmittance / Haze Value (Haze Value)) The total light transmittance and haze value are turbidimeters (“NDH2000” manufactured by Nippon Denshoku Co., Ltd.) according to JIS K7105.
Was measured using. The haze value is defined by the following formula. The larger the haze value, the greater the cloudiness, indicating that the deterioration is progressing. Haze value (%) = diffuse transmittance / total light transmittance × 100

[0064]

[Table 1]

[0065]

INDUSTRIAL APPLICABILITY The present invention utilizes an aqueous photocatalyst coating agent to uniformly and firmly adhere a photocatalyst layer to a substrate,
It is a method for producing a photocatalyst having excellent scratch resistance and weather resistance, is easy to handle, and can reduce the load on the environment during production. The obtained photocatalyst can also be used as a landscape material for roads, roofs, side walls, etc., and as an outer wall material.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a photocatalyst body of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the photocatalyst body of the present invention.

[Explanation of symbols]

1 Photocatalyst 2 base materials 3 Hydrophilic silicone resin layer 4 Photocatalyst layer 5 Primer layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomoyuki Tahara             1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Made in Kawasaki             Technical Research Institute of Iron Co., Ltd. (72) Inventor Hiroyuki Fukui             1-28 Kitahonmachi-dori, Chuo-ku, Kobe-shi, Hyogo             No. Kawakawa Building Materials Co., Ltd. F-term (reference) 4G069 AA03 AA08 BA02B BA04B                       BA27A BA27B BA48A BD05A                       BD05B CA10 DA06 EA08                       EC22Y FA03 FB24 FC05

Claims (6)

[Claims] 1. A hydrophilic silicone resin layer comprising a substrate, a silicone resin coating formed on at least a part of the surface of the substrate and having a contact angle with water of 20 ° or less, and on the resin layer. A photocatalyst body comprising a photocatalyst layer containing photocatalyst particles and a metal oxide binder. 2. A hydrophobic and / or water-repellent silicone resin coating is applied to at least a part of the surface of a base material, and the surface of the obtained coating is irradiated with ultraviolet rays to be hydrophilized and then contacted with water. After forming a hydrophilic silicone resin layer composed of a silicone resin coating having an angle of 20 ° or less, an aqueous photocatalytic coating agent containing photocatalyst particles and a metal oxide binder is applied onto the resin layer to form a photocatalyst layer. Forming a photocatalyst. 3. The method for producing a photocatalyst body according to claim 2, wherein the ultraviolet rays include ultraviolet rays having a wavelength of 185 nm or less. 4. A hydrophilic silicone resin coating is applied to at least a part of the surface of a base material to form a hydrophilic silicone resin layer made of a silicone resin coating having a contact angle with water of 20 ° or less. A method for producing a photocatalyst body, comprising forming a photocatalyst layer by coating an aqueous photocatalyst coating agent containing photocatalyst particles and a metal oxide binder on the resin layer. 5. The method for producing a photocatalyst body according to claim 4, wherein the hydrophilic silicone resin coating material contains a hydrolyzate of a tetrafunctional alkoxysilane in an amount of 80% by mass or more. 6. The photocatalyst layer is formed by applying the photocatalyst coating agent and then heating and / or irradiating ultraviolet rays having a wavelength of 315 nm or less. A method for producing a photocatalyst.