JP2016150329A - Organic substrate having photocatalyst layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic substrate with a base layer having a photocatalyst layer that is easily treated without causing a choking phenomenon on the surface of the organic substrate and has sufficient adhesion, coating performance, and transparency in a practical use, and also has excellent photocatalytic activity and film strength.SOLUTION: A base layer is made of a coating composition that contains an alkoxysilane compound of 10-120 pts.wt. relative to 100 pts.wt. of alumina hydrate particles in an alumina sol having the alumina hydrate particles of a minor axis of 1-10 nm, a major axis of 100-10,000 nm, and an aspect ratio (major axis/minor axis) of 30-5,000. An organic substrate having a photocatalyst layer is characterized in that the base layer is coated with a coating solution having ultrafine particles of an average primary particle diameter of 0.1 μm or less of photocatalytic titanium oxide dispersed in water and/or alcohol to form the photocatalytic layer.SELECTED DRAWING: None

Description

The present invention relates to an organic base material having a photocatalyst layer on the surface of an organic base material that has good adhesion and does not cause deterioration (choking) of the base material.

It has been conventionally known that titanium oxide or the like functions as a photocatalyst and decomposes or oxidizes a substance when irradiated with light. Using this photocatalytic action, for the purpose of environmental purification of indoor and outdoor spaces (e.g. deodorization, antifouling, antibacterial, antifungal, etc.), a trace amount of harmful components present in that space, especially harmful organic components including microorganisms Attempts have been made to remove. For example, it has been widely used to form a photocatalyst layer of titanium oxide or the like on an inorganic base material such as glass, tile, or building material, and to decompose organic substances attached to or in contact with the base material.

Although there are various methods for forming the photocatalyst layer, a so-called dip method and an ultrafine particle dispersion coating method are generally used. In the so-called dip method, a metal alkoxide constituting the photocatalyst layer on the substrate, for example, when the photocatalyst layer is titanium oxide, a coating solution containing titanium alkoxide is applied and baked at a temperature of 400 to 500 ° C. It is a method of forming. The photocatalyst layer obtained by this production method is durable because of its excellent film strength. However, in general, since baking at 400 ° C. or higher is required, the applicable base material is substantially limited to an inorganic base material having excellent heat resistance. On the other hand, in the ultrafine particle dispersion coating method, a dispersion in which photocatalytic ultrafine particles such as titanium oxide having an average primary particle diameter of 0.1 μm or less are dispersed in water, alcohol, or the like or a solution thereof is applied to a substrate. In this method, the photocatalyst layer is obtained by heating and drying. The photocatalyst layer film obtained by this production method has high crystallinity and excellent photocatalytic properties. Furthermore, in the latter case, recently, a coating liquid obtained by coating a photocatalyst that can be baked by a treatment at 200 ° C. or lower is also commercially available. However, even if the photocatalyst layer is provided on the organic base material by such an ultrafine particle dispersion coating method, there are the following problems.

In addition to conventional inorganic base materials, there is an increasing demand for forming a photocatalyst layer on organic base materials such as plastics, films, and wood, or on metal base materials provided with organic paints, to provide a function for removing harmful components. ing. However, since photocatalysts decompose organic substances when irradiated with ultraviolet rays, when a photocatalyst layer is formed on an organic base material, the photocatalyst layer deteriorates the base material surface itself, and adhesion to the base material deteriorates. There is a problem that a phenomenon called choking occurs in which a transparent substrate becomes cloudy.

As a means for preventing the deterioration of the organic base material due to the chalking, a hydrolyzable silicon compound such as an alkyl silicate, a silicon halide, and a partial hydrolyzate thereof is provided between the organic base material and the photocatalyst layer. Products obtained by decomposition, organic polysiloxane compounds and their polycondensates, silica, colloidal silica, water glass, silicon compounds, phosphates such as zinc phosphate, metal oxides such as zinc oxide and zirconium oxide, Attempts have been made to interpose an intermediate layer serving as a protective layer and an adhesive layer, such as phosphate, cement, gypsum, lime, enamel frit. As a typical inorganic base layer, a resin film as a base material is subjected to corona discharge treatment, a primer coating made of a silicone resin is applied and dried, and then a silicone hard coat agent is applied and dried. After the corona discharge treatment is applied to the system hard coat agent, a titanium oxide-containing coating composition (for example, anatase-type titanium oxide sol, silica sol, and ethanol diluted with trimethoxysilane) is applied and cured by heat treatment. As described above, in order to fix the photocatalyst layer to the resin film, it is necessary to apply a coating agent related to the very multi-step adhesion, and the adhesive force is not sufficient. It was high.

For the purpose of shortening these steps, Patent Document 1 (Japanese Patent Application Laid-Open No. 2000-225663) discloses a method in which silicone primer treatment and corona discharge treatment can be omitted, that is, silicon oxide and / or aluminum oxide on a resin film. In this method, a thin film layer for protecting a resin film needs to be formed by vacuum deposition or the like. The effect of improving the complexity of the process for producing the product was very small.
That is, conventionally, in an organic base material having a photocatalyst layer, it is not yet possible to obtain a base layer that prevents choking, is easy to process, and has practically sufficient adhesion, film property, and transparency. Currently.

On the other hand, the alumina contained in the alumina sol may exhibit various forms such as a plate shape, a column shape, a needle shape, a particle shape, and a fiber shape. The physical properties of the alumina sol vary depending on the form of the alumina, and the use of the alumina sol varies depending on the physical properties. However, it is difficult to selectively produce alumina having a specific form by controlling the form of alumina by controlling the production conditions and the like, and development related to form control of alumina is currently underway. Patent Document 2 (Japanese Patent Application Laid-Open No. 2010-132519), as a document relating to alumina having a specific aspect ratio, is selected from the group consisting of fibrous or acicular boehmite and pseudoboehmite obtained by hydrolysis of aluminum alkoxide. An alumina sol comprising alumina hydrate particles having at least one crystal form, wherein the alumina hydrate particles have a minor axis of 1 to 10 nm, a major axis of 100 to 10,000 nm, and an aspect ratio (major axis / minor axis). An alumina sol of 30 to 5,000 and a method for its production are described. Such alumina sol is commercially available from Kawaken Fine Chemical Co., Ltd.

Patent Document 3 (Japanese Patent Application Laid-Open No. 2011-255303) states that “the range of pore diameters that can be controlled is wide and has practically high heat resistance, organic solvent resistance, water resistance, high resistance and low pH resistance. A fibrous or needle-like product obtained by hydrolysis of aluminum alkoxide for the purpose of providing an alumina composite separation membrane having a simple membrane formation method and low cost and a method for producing the same ”(paragraph [0009]). An alumina sol comprising alumina hydrate particles having at least one crystal form selected from the group consisting of boehmite and pseudoboehmite, wherein the alumina hydrate particles have a minor axis of 1 to 10 nm, a major axis of 100 to 10, Alkoxysila such as 3-glycidoxypropyltrimethoxysilane in an alumina sol having an 000 nm aspect ratio (major axis / minor axis) of 30 to 5,000. By coating the coating liquid containing the compound uniformly and the coating liquid, “fibrous alumina particles are stacked in parallel in one direction, and between the parallel and stacked fibrous alumina particles. "Alumina composite separation membrane characterized in that pores communicating with each other are formed" (Claims 1 to 6 and Example 5) are described.

Furthermore, Patent Document 4 (Japanese Patent Laid-Open No. 2013-216760) also provides a coating composition that can easily form an alumina thin film having excellent film forming properties, denseness, gas barrier properties, thermal stability, electrical insulation, and the like. For this purpose, a coating composition (claim 1) is described in which the alumina sol described in Patent Document 3 contains a silane coupling agent such as 3-glycidoxypropyltrimethoxysilane.

However, in these patent documents, there is no description as to whether or not the porous organic-inorganic composite film is effective as an underlayer with respect to prevention of choking of an organic base material having a photocatalyst layer. It is unpredictable how the porosity and the inclusion of the organic component affect choking.

JP 2000-225663 A JP 2013-216760 A JP 2011-255303 A JP 2011-255303 A

The object of the present invention is that the surface of an organic base material does not cause the choking phenomenon, is easy to process, has practically sufficient adhesion, film property and transparency, and has photocatalytic activity and film strength. Is to provide an organic base material with a base layer having a good photocatalyst layer.

The object is achieved by the following means.
(1) From alumina hydrate particles having at least one crystal form selected from the group consisting of fibrous or acicular boehmite and pseudoboehmite obtained by hydrolysis of aluminum alkoxide on the surface of an organic base material Alumina sol, wherein the alumina hydrate particles have a minor axis of 1 to 10 nm, a major axis of 100 to 10,000 nm, and an aspect ratio (major axis / minor axis) of 30 to 5,000. An underlayer is formed from a coating composition containing 10 to 120 parts by weight of an alkoxysilane compound with respect to 100 parts by weight of the product particles, and ultrafine photocatalytic titanium oxide having an average primary particle size of 0.1 μm or less is further formed thereon. A photocatalyst layer provided with a photocatalyst layer by coating a coating liquid in which water is dispersed in water and / or alcohol Organic substrate having a.
(2) In the above (1), the liquid component of the coating composition of the base layer is a base layer formed of a coating composition that is an aqueous liquid containing 10 to 50% by weight of ethanol. An organic base material having a photocatalytic layer.
(3) In the above (1) or (2), the alkoxysilane compound is an underlayer formed of a coating composition that is at least one alkoxysilane compound selected from an epoxy group and an amino group. An organic base material having a photocatalytic layer.

According to the invention of the above (1), the alumina hydrate particles having at least one crystal form selected from the group consisting of fibrous or needle-like boehmite and pseudoboehmite which are constituent components have a minor axis of 1 to 10 nm. A major axis of 100 to 10,000 nm, an aspect ratio (major axis / minor axis) of 30 to 5,000, and a combination of a quaternary ammonium salt-containing alkoxysilane compound. A base layer made of a transparent and porous organic-inorganic composite film having good adhesion to the film, high film hardness, flexibility and no cracks is formed, and an average primary particle diameter of 0.1 μm or less is formed on the base layer By providing a photocatalyst layer by applying a coating liquid in which ultrafine photocatalytic titanium oxide is dispersed in water and / or alcohol, a choking phenomenon can be produced even after long-term use. Without Rukoto, practically sufficient adhesion has a film resistance, and transparency, and the photocatalytic activity is possible to provide a base layer with an organic base material having good photocatalytic layer.
According to the invention of (2), the base layer is directly coated on the organic base material having a hydrophobic surface without hydrophilizing the surface of the organic base material by physical or chemical treatment. A substrate can be provided.
According to the invention of (3), the adhesion between the base material and the base layer and the base layer and the photocatalyst layer can be improved with respect to a wide variety of base materials without deteriorating the dispersion stability of the base layer coating liquid. It is possible to provide a stronger base material.

According to the method of the present invention, first, a base paint is applied to the surface of an organic base material to form a base layer made of fibrous boehmite having a specific aspect ratio and an alkoxysilane compound. A photocatalytic layer made of ultrafine photocatalytic metal oxide having a primary particle size of 0.1 μm or less is applied to form a photocatalytic layer. That is, a photocatalytic film is formed on an organic base material via a specific underlayer. Below, an organic type base material, the coating liquid for base layers, the coating liquid for photocatalysts, and the film-forming method are demonstrated in order.

(Organic substrate) Specific examples of the organic substrate suitable for forming the photocatalyst layer of the present invention include plastic films and sheets. Specifically, polyethylene terephthalate film (hereinafter referred to as PET film), polypropylene film, polyethylene film, vinyl chloride film, vinylidene chloride film, acrylic film, nylon film, fluorine film, polyvinylidene fluoride film, polycarbonate film, etc. Can be given. Among these, a biaxially stretched polyethylene terephthalate film is desirable. The surface of the plastic film may be subjected to surface treatment such as corona discharge treatment, glow treatment, or plasma treatment. Moreover, an adsorption layer such as an adhesive layer or silicone rubber may be provided on the opposite side of the plastic film or sheet provided with the photocatalyst layer of the present invention.

Other examples include covers for various types of lighting (eg, automotive lighting, tunnel lighting, fluorescent light, white light bulbs, etc.), lenses, dishes and cooking containers (eg, balls, cereals, storage containers), ventilation fans, spectacle lenses And frames, goggles, helmet shields, signs, signs, household appliance housings, range hoods, sinks (eg, vinyl chloride), kitchen counters (eg, artificial marble), sanitary equipment and accessories (eg, Western toilets) Pedestal and lid), bathtub (eg, FRP), furniture (eg, melamine resin table board, plastic chair), indoor or outdoor exhibition and display (eg, information board), outdoor furniture (eg, bench) And play equipment, outdoor fixed structures (eg, highway soundproof walls), various plastic moldings, including building materials (corrugated, acrylic), wooden or other vegetable building materials, interior materials and building accessories (Doors, shoji, fusuma, screens, blind, mats, etc.), a wall sprayed material, natural and synthetic fibers and fabrics, paper, and leather, and the like.

However, the organic base material is not limited to this. These base materials can form the base layer and the photocatalyst layer of the present invention either in the state of the material before commercialization or after commercialization. In addition, even if the base material is inorganic such as metal, it is preferable to apply the method of the present invention when an organic paint is applied for anticorrosion or aesthetics. In this case, if the formation of the underlayer is omitted, the coating film on the surface of the substrate is deteriorated by the photocatalytic film.

In the present invention, fibrous or acicular boehmite and pseudoboehmite, which are constituents of the underlayer, have a minor axis of 1 to 10 nm, a major axis of 100 to 10,000 nm, and an aspect ratio (major axis / minor axis) of 30 to 5,000. Regarding the method for producing alumina hydrate particles (hereinafter referred to as alumina nanofibers) having at least one crystal form selected from the group consisting of the above, the descriptions in Patent Documents 2, 3, and 4 can be incorporated. Specifically, it can be purchased as “trade name F3000 nanofiber sol (solid content 5%, pH 3)” from “Kawaken Fine Chemical Co., Ltd.”.

The alumina nanofiber used in the present invention has a minor axis of 1 to 10 nm, a major axis of 100 to 10,000 nm, and an aspect ratio (major axis / minor axis) of 30 to 5,000. When the average minor axis is less than 1 nm, the particles are fine, so that they tend to aggregate, thereby increasing the viscosity and reducing the storage stability. If it is 10 nm or more, the flexibility of the resulting film is low. Further, the ratio of the major axis to the minor axis, that is, the aspect ratio (major axis / minor axis) is preferably in the range of 30 to 5,000, and more preferably in the range of 100 to 3,000. If the aspect ratio is less than 30, it is not preferable because the film formability is lowered and cracks are easily generated. On the other hand, if this aspect ratio exceeds 5,000, it takes a long time to synthesize alumina nanofibers, which is not practical, and a film made of this type of macromolecule is poor in transparency and flexibility. Therefore, it is not preferable.

The crystal form of alumina includes amorphous, boehmite, pseudoboehmite, γ-alumina, θ-alumina and α-alumina. In the present invention, the alumina nanofiber has the above dimensions, and the alumina thin film has sufficient strength. In order to exhibit the above, it is preferable that the alumina nanofibers contained in the sol are at least boehmite crystal form alumina nanofibers and / or pseudo boehmite crystal form alumina nanofibers. That is, the crystal form may be a mixture containing boehmite and / or pseudoboehmite as a main component and containing other crystal forms. In the present invention, the alumina nanofibers contained in the sol are particularly preferably boehmite crystal form and / or pseudo boehmite crystal form. Here, boehmite is a crystal of alumina hydrate represented by a composition formula: Al ₂ O ₃ .nH ₂ O.

In addition, the solid content concentration of the alumina nanofiber sol stock solution is preferably 2 to 10% by weight when the stock solution is produced. When the solid content concentration is less than 2% by weight, the aspect ratio of the obtained alumina nanofiber may be smaller than a predetermined value. On the other hand, if the solid content concentration exceeds 10% by weight, the stirrability of the reaction solution is greatly reduced during hydrolysis of the aluminum alkoxide / solubilization of the peptization. However, as a coating solution, it is possible to dilute and use the stock solution at the time of use.

Hydroxyl groups are present on the surface of the alumina nanofiber particles used in the present invention, and these hydroxyl groups can be easily modified. For this modification, a silane coupling agent, a silylating agent, a polyhydric alcohol, an aluminum chelate compound, a titanium chelate compound, an aromatic sulfonic acid, phosphoric acid, a long chain carboxylic acid, or the like can be used as a modifying agent.
From the viewpoint of adhesion to an organic base material and formation of a film-forming film, a silane coupling agent made of alkoxysilane is particularly preferable as the modifier.

If an alkoxysilane compound is taken as an example of the modifier, the compounding amount is preferably 10 to 100 parts by weight of the alkoxysilane compound with respect to 100 parts by weight of the alumina nanofiber. When the content of the alkoxysilane compound is less than 10 parts by weight, depending on the type of the organic substrate, sufficient adhesion between the organic substrate and the base layer may be lacking. Moreover, when it exceeds 100 weight part, the organic component of a base layer will increase and it is unpreferable. By combining an alkoxysilane compound with alumina nanofibers in this way, cracking of the alumina thin film is suppressed, pore diameter is reduced, flexibility is improved, adhesion to the substrate is increased, and film hardness is increased. The effects such as improvement are remarkably obtained.

Specific examples of the alkoxysilane compound of the present invention include, for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxy Epoxy system such as propylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) Amino systems such as -3-aminopropyltrimethoxysilane, methacrylic systems such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, isocyanate systems such as 3-isocyanatopropyltriethoxysilane, Examples include, but are not limited to, alkoxysilane compounds (silane coupling agents) such as mercaptopropylmethyldimethoxysilane, mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, and isocyanate-based compounds such as 3-isocyanatopropyltriethoxysilane. It is not a thing. These alkoxysilane compounds are appropriately selected depending on the type of substrate to be coated. In particular, silane coupling agents composed of epoxy-based alkoxysilane compounds and amino-based alkoxysilane compounds adhere to a wide variety of organic substrates. It is particularly preferable from the viewpoint of safety.

The total solid content concentration in the coating composition according to the present invention is defined by the solid content of the alumina nanofibers. The solid content of alumina nanofibers is 0.1 to 5% by weight, preferably 0.5 to 3.5% by weight. The thickness of the underlayer according to the present invention is preferably 0.05 μm to 2 μm, particularly preferably 0.1 μm to 1.5 μm. If the film thickness is less than 0.05 μm, uniform application is difficult, while the thickness exceeding 1.5 μm is useless.

The base coating composition according to the present invention may contain a polar organic solvent such as ethanol or DMF, if necessary. Examples of the polar organic solvent include alcohols, ketones, ethers, etc. As the added polar organic solvent capable of maintaining the dispersion stability of the alumina nanofiber / alkoxysilane compound aqueous dispersion, ethanol and DMF are preferable, and the safety, etc. From this point of view, ethanol is particularly preferable as the additive solvent. In addition, other organic solvents may be added as long as they do not adversely affect as necessary. Accordingly, for example, not only coating on a hydrophilic substrate such as glass but also uniform coating on a hydrophobic substrate such as a polyester film that has not been subjected to a hydrophilic treatment becomes possible. The amount of ethanol or DMF added depends on the type of substrate, but the aqueous liquid component of the coating composition is preferably an aqueous liquid containing 10 to 50% by weight of ethanol or DMF. If it is less than 10% by weight, the wettability of the coating liquid to a hydrophobic substrate such as a polyester film is not sufficient, and a uniform coating film cannot be obtained. If it exceeds 50% by weight, the dispersion stability of alumina nanofibers may be adversely affected. Moreover, it is contrary to the gist of the present invention to provide a highly safe coating composition by reducing the amount of organic solvent as much as possible.

When the heat treatment temperature of the coating film is limited to 100 ° C. or lower due to the properties of the coating object or other factors, a curing agent is added as a catalyst to the coating composition to accelerate the curing reaction of the coating film. Also good. As such a curing agent, for example, an aluminum chelate compound, hydrogen peroxide, aminoethylethanolamine, an imidazole metal complex salt or the like can be added in an amount of 1 to 5% by weight based on the solid content of the coating composition.

The method for applying the coating composition according to the present invention can be appropriately selected according to the type and shape of the substrate. Application | coating can be implemented by methods, such as spin coating, roll coating, spray coating, bar coating, a dipping method, for example.

Although the coating film can be dried at room temperature, it is preferably heated to shorten the drying time. The drying temperature is preferably 50 ° C. or higher and 180 ° C. or lower, and preferably not higher than the heat resistant temperature of the substrate. It is not necessary to dry the underlayer coating film until the coating film is completely cured, and it is sufficient that the organic solvent is substantially removed.

(Photocatalyst layer) The photocatalyst layer of the present invention is formed by a dispersion coating method in which an ultrafine photocatalytic metal oxide having an average primary particle size of 0.1 μm or less is dispersed in water, alcohol, or a mixed aqueous solution of water and alcohol. The photocatalyst layer is formed. That is, a coating liquid in which ultrafine photocatalytic metal oxide having an average primary particle diameter of 0.1 μm or less is dispersed in a polar organic solvent such as water or alcohol, or an aqueous liquid that is a mixture of water and a polar solvent. It is formed by work. If necessary, other polar solvents other than alcohol may be added.

(Photocatalyst particles) The constituent of the photocatalyst layer formation of the present invention contains photocatalytic metal oxide particles, but the type of the photocatalyst particles is limited as long as it can exhibit practically sufficient photocatalytic activity. Not. However, titanium oxide compounds such as titanium dioxide are particularly preferable. Specific examples of the titanium oxide compound include anatase type titanium oxide, rutile type titanium oxide, and brookite type titanium oxide. Among these, anatase-type titanium oxide and brookite-type titanium oxide are particularly preferable from the viewpoint of photocatalytic activity, and anatase-type titanium dioxide is particularly preferable in view of cost. Further, other photocatalyst particles that may be doped with a conventionally known additive in order to develop visible light responsiveness include, for example, tungsten oxide, zinc oxide, tin oxide, and zirconium oxide. .

Furthermore, in the present invention, photocatalyst particles such as titanium oxide are used in the form of ultrafine particles having an average primary particle diameter of 0.1 μm or less. When the average primary particle diameter exceeds 0.1 μm, the transparency of the photocatalyst layer cannot be obtained. The photocatalyst particles such as titanium oxide preferably have an average primary particle diameter of 0.05 μm or less, particularly preferably 0.001 μm to 0.030 μm. As the average primary particle size is smaller, not only the transparency of the photocatalyst layer is improved, but also the adhesion with the base layer is improved, and low-temperature baking is possible.
These ultrafine particle titanium oxide powders are commercially available, for example, as P-25 manufactured by Nippon Aerosil Co., Ltd. and ST series manufactured by Ishihara Sangyo Co., Ltd.

(Photocatalyst layer coating solution) In order to obtain a photocatalyst layer coating solution using the ultrafine particle titanium oxide powder or the like, a dispersant or a binder is usually used in water, alcohol or a mixed aqueous solution of water and alcohol. Together with the agent, the ultrafine titanium oxide is stably dispersed. For example, the composition etc. which contained the photocatalyst in the composition which has either the hydrolyzate of alkyl alkoxysilanes, its condensate, or both as a main component are mentioned. The content of the photocatalyst in the coating agent containing the photocatalyst is not particularly limited as long as it is included in a necessary amount, but is preferably 0.05% by weight to 10% by weight.
However, since the organic base material is generally inferior in heat resistance, the photocatalyst layer coating solution used in the present invention is dried and baked at 180 ° C. or lower after application to the organic base material. Therefore, it is desirable that a photocatalyst layer having a desired strength can be formed. A coating solution for an ultrafine titanium oxide photocatalyst layer that satisfies such conditions and has a good photocatalytic activity and an average primary particle size of 0.1 μm or less is a prior art described in a conventionally known patent document (for example, No. 10-195341, No. 98/015600, etc.) can be used.

Furthermore, as a commercial product of a photocatalyst layer coating solution that can be used in the present invention, for example, coating agent manufactured by Teika Co., Ltd., trade name: TKC-303 (anatase type titanium oxide, solid content: 13 wt%, crystallite size: 6 nm , Medium; water, PH; acidity, normal temperature curing), trade name: TKC-304 (anatase type titanium oxide, solid content: 9% by weight, crystallite size: 6 nm, medium: water, PH; neutral, normal temperature curing) , Manufactured by Ishihara Sangyo Co., Ltd., trade name: ST-K211 (anatase-type titanium oxide, solid content: 0.2% by weight, ultrafine particles, medium: alcohol / water, containing inorganic binder, low-temperature baking possible), Showa Denko KK Manufactured, trade name: NTB-13 (Brook Kite type titanium oxide, solid content: 3% by weight, ultrafine particles, medium: water, PH; 2, binder contained, low temperature (80 ° C. to 150 ° C.) baking ), Manufactured by Taki Chemical Co., Ltd., Tynock CZP-223 (anatase type titanium oxide, solid content: 2% by weight, siloxane binder 0.5% by weight, titanium oxide crystallite diameter 10 nm, medium: water, low temperature baking), others "Vistrator L" (trade name, manufactured by Nippon Soda Co., Ltd.), "Fressera P-S1000" (trade name, manufactured by Panasonic Electric Works Co., Ltd.), "PSC-50, PSH-10" (JSR Corporation) Etc., and these can be used.

The coating method of the coating agent containing the photocatalyst is not particularly limited. For example, a roller coating method, a bar coating method, a spray coating method, an air knife coating method, a spin coating method, a flow coating method, a curtain coating method, and a dipping method. Etc.

The film thickness of the photocatalyst layer is preferably formed to be 0.05 to 2 μm, and more preferably 0.1 to 1 μm. By setting the film thickness to 0.05 μm or more, the antifouling function and hydrophilicity of the resin molded product are improved. Moreover, the crack generation at the time of hardening can be suppressed and a weather resistance can be improved because a film thickness shall be 2 micrometers or less.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.

The following coating liquids (a) to (d) were prepared as coating solutions for the underlayer.
Underlayer coating liquid (A): F-3000 alumina nanofiber sol (5 wt% solid water sol) manufactured by Kawaken Fine Chemical Co., Ltd. was diluted with ion-exchanged water so as to have the following solid content. On the other hand, 3-glycidoxypropyltrimethoxysilane (KBM-403: manufactured by Shin-Etsu Silicone) is dissolved in ethanol so as to have the following weight ratio, and the ethanol solution is added to the alumina nanofiber sol dilution. Then, the mixture was stirred for 30 minutes at 50 ° C. to prepare a coating solution (a) for an underlayer. Alumina nanofiber solid content 2% by weight, alumina nanofiber solid content weight / KBM-403 weight = 100/33 weight ratio, total solid content; 2.67% by weight, water / ethanol weight ratio = 67: 33.
Underlayer coating solution (I): The alumina nanofiber sol was diluted with ion-exchanged water so as to have the following solid content. On the other hand, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane (KBM-603: manufactured by Shin-Etsu Silicone) and the KBM-403 were dissolved in ethanol so as to have the following weight ratio. The solution was added to the diluted alumina nanofiber sol, and stirred at 50 ° C. for 30 minutes to prepare a coating solution (a) for an underlayer. Alumina nanofiber solid content 1.0 wt%, alumina nanofiber solid content weight / KBM-603 / KBM-403 weight = 100/10/23 weight ratio, total solid content; 1.33 wt%, water / ethanol weight ratio = 67: 33.
Underlayer coating solution (c) The alumina nanofiber sol was diluted with ion-exchanged water so as to have the following solid content. On the other hand, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane (KBM-603: manufactured by Shin-Etsu Silicone) was dissolved in ethanol so as to have the following weight ratio, and the ethanol solution was dissolved in the alumina nano It added to the fiber sol dilution and stirred at 50 ° C. for 30 minutes to prepare a coating solution (c) for the underlayer. Alumina nanofiber solid content 0.8% by weight,
Solid weight of alumina nanofiber / KBM-603 / = 100/50 weight ratio, total solid content; 1.2% by weight, water / ethanol weight ratio = 67: 33.
Underlayer coating liquid (d): The alumina nanofiber sol was diluted with ion-exchanged water so that the solid content of alumina nanofibers was 2% by weight. Thereafter, the KBM-403 is added so that the weight ratio of solid content of alumina nanofiber / KBM-403 weight = 100/33 weight ratio is added to the diluted solution of alumina nanofiber sol, and stirred at 50 ° C. for 30 minutes. A stratum coating solution (D) was prepared. Total solid content: 2.67% by weight

As an organic base material, a 50 μm PET film (v) that has not been surface-treated, a PET film (f) that is glow-treated on the PET film (v), and a polyester resin for forming a hydrophilic film on the PET film (v) (Takamatsu) Three types of PET film (ki) with 0.3 μm thickness of Pesresin A613D manufactured by Yushi Co., Ltd. were prepared.

As a coating solution for forming a photocatalyst layer, Tainok CZP-223 (anatase type titanium oxide, solid content: 2% by weight, siloxane binder 0.5% by weight, titanium oxide crystallite diameter 10 nm, medium: water, manufactured by Taki Chemical Co., Ltd. , Low temperature baking, transparent film formation) and Ishihara Sangyo Co., Ltd., trade name: ST-K211 (anatase type titanium oxide, solid content: 0.2 wt%, ultrafine particles, medium: alcohol / water, inorganic binder contained, low temperature A photocatalyst coating liquid (ku) and a photocatalyst coating liquid (ke) were prepared.

On each said base film, each base layer coating liquid was apply | coated so that it might become a dry film thickness as shown in Table 1 by the bar-coat method, and it dried at 120 degreeC for 2 minute (s). Thereafter, each photocatalyst layer coating solution was applied to a dry film thickness as shown in Table 1, and dried at 130 ° C. for 5 minutes.

(Evaluation method) The adhesion of the photocatalyst film was evaluated by the number of squares peeled off by the crosscut / tape peeling test (100 squares). Further, an ultraviolet lamp (1.2 mW / cm ² ) was continuously irradiated for 2 weeks at a distance of 10 cm ² from the photocatalyst film side of the sample, and the presence or absence of choking after the light irradiation was visually determined according to the following criteria.
○: No choking, Δ: Some choking, ×: Choking entirely.

The evaluation results are shown in Table 2.

According to the present invention, it is possible to form a photocatalyst film excellent in transparency and durability by using ultrafine photocatalyst particles without causing any chalking of the base material to the organic base material. . Therefore, it becomes possible to use a photocatalyst film for an organic base material such as plastic, which could not be applied for choking, and the use of the photocatalyst film is greatly expanded.

Claims (3)

An alumina sol composed of alumina hydrate particles having at least one crystal form selected from the group consisting of fibrous or acicular boehmite and pseudoboehmite obtained by hydrolysis of aluminum alkoxide on the surface of an organic base material The alumina hydrate particles 100 are contained in an alumina sol having a minor axis of 1 to 10 nm, a major axis of 100 to 10,000 nm, and an aspect ratio (major axis / minor axis) of 30 to 5,000. An undercoat layer is formed from a coating composition containing 10 to 120 parts by weight of an alkoxysilane compound with respect to parts by weight, and ultrafine photocatalytic titanium oxide having an average primary particle size of 0.1 μm or less is further added to water and A photocatalyst layer characterized by having a photocatalyst layer provided by applying a coating liquid dispersed in alcohol. An organic substrate that. 2. The photocatalyst layer according to claim 1, wherein the liquid component of the coating composition of the underlayer is an underlayer formed of a coating composition that is an aqueous liquid containing 10 to 50% by weight of ethanol. Organic base material. The photocatalyst layer according to claim 1 or 2, wherein the photocatalyst layer is an underlayer formed of a coating composition in which the alkoxysilane compound is at least one alkoxysilane compound selected from an epoxy group and an amino group. An organic base material.