JP2002080782A - Photo-catalytic coating film-forming composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating film-forming composition capable of forming a transparent photo-catalytic film having a high hardness and excellent in scratch resistance while maintaining the designing property and transparency of a base material by using a low cost wet method. SOLUTION: This photo-catalytic coating film-forming composition consists of a titanium compound of which particle surface is stabilized by 0.1-2.0 weight ratio chelating agent based on the titanium compound, having 1-100 nm mean particle diameter, a hydrolysate of a hydrolyzable silicon compound expressed by the general formula: SiX3(OSi)nX3 [wherein, (n) is 0 or 1-8 integer; X's are a halogen or a 1-8C alkoxy and may be the same or different] and a solvent, and has (30:70)-(90:10) ratio of titanium to silicon based on the converted values of TiO2 and SiO2 and <=20 wt.% solid portion concentration in the whole composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel composition capable of forming a titanium oxide-containing coating film used as a photocatalyst, a film using the same, and a glass having the film formed on the surface. The present invention relates to a novel member applied to a surface of metal, cement, wallpaper, gypsum board, stone, ceramics, resin, or the like.

[0002]

2. Description of the Related Art Photocatalytic coating compositions having functions such as anti-fogging, self-cleaning by rainfall, and decomposition of harmful substances due to their superhydrophilicity and decomposition activity are actively studied as environmentally friendly high-functional surface coating materials. Development is taking place. However, in order to form a transparent photocatalytic film having high hardness and high scratch resistance that can withstand a wide range of use conditions while maintaining sufficient photocatalytic activity while maintaining the design and transparency of the base material. Is a costly sputtering method, CVD
There is no other choice but to use a plasma method or a plasma method, and a coating method and a coating film composition that realize high hardness and high scratch resistance at low cost are strongly desired.

[0003] Further, even in a film forming method capable of obtaining a transparent and hard film, there is a problem that a film cannot be formed depending on a base material in a sputtering method, a CVD method, a plasma spraying method or the like.
The method of baking alkoxide requires a heat treatment at a high temperature, and has a problem that it can be applied only to a substrate that can withstand a high temperature.

On the other hand, in a wet method such as a sol-gel method which is low in cost and can be applied to many substrates, a film-forming composition satisfying all mechanical properties such as transparency, photocatalytic activity, hardness and abrasion resistance is required. Not yet obtained. In order to form a transparent and hard photocatalytic film, a measure is generally taken to increase the content of a binder component such as silica to reduce the film thickness.
As a result, the content of the photocatalyst decreases and the activity decreases. Further, in order to form a coating film having high photocatalytic activity, measures are taken to increase the content of the photocatalytic component, but as a result, the hardness and abrasion resistance of the film are reduced.

There have been several examples of providing a photocatalytic film satisfying all of transparency, photocatalytic activity, hardness and abrasion resistance by using a wet method by using additives and the like. , Haze is about 0.4% ~ 0.8%, and pencil hardness is only 3H ~ 6H. Sufficient properties are realized for applications requiring all of designability, hardness, abrasion resistance, etc. I haven't. JP-A-11-323190 discloses that ultrafine titanium oxide having an average primary particle diameter of 0.1 μm or less produced by a gas phase method is dispersed in an organic solvent containing β-diketone and a titanate-based or aluminum-based coupling agent. A photocatalyst paint obtained by mixing the solution obtained by hydrolysis of ethyl silicate with the dispersed liquid is applied to the base material, and dried by heating to provide high film strength even with a small amount of binder. We provide photocatalytic coatings with excellent activity. However, as shown in the same paragraph (0061), in this example, the haze of the coating film was 0.1.
With a pencil hardness of 4% to 0.6% and a pencil hardness of 2H to 3H, it cannot be said that transparency and hardness necessary for application to a wide range of applications are sufficiently realized. In Japanese Patent Application Laid-Open No. 11-323191,
Ethyl silicate containing a fluorine-based surfactant is added to a dispersion of fine particle titanium oxide having an average temporary particle diameter of 0.1 μm or less in an organic solvent containing a β-diketone and a titanate-based or aluminum-based coupling agent. By applying a photocatalytic paint mixed with a solution of a decomposition product to a substrate and drying by heating, a photocatalytic film having high film strength even with a small amount of a binder and excellent in transparency and photocatalytic activity is provided. However, as shown in the same paragraph (0055), in this example, the haze of the coating film was 0.1.
With a pencil hardness of 4% to 0.8% and a pencil hardness of 3H to 6H, it cannot be said that transparency and hardness required for application to a wide range of applications are sufficiently realized. Japanese Patent Application Laid-Open No. 2000-273355 discloses that an organic material containing β-diketone and a titanate or aluminum-based coupling agent is prepared by using a fine particle titanium oxide powder having an average primary particle diameter of 0.01 to 0.1 μm produced by a gas phase method. A high photocatalytic activity is obtained by applying a photocatalytic coating obtained by dispersing the resulting dispersion in a solvent and mixing the obtained dispersion with a solution of a partial hydrolyzate of titanium alkoxide serving as a binder to a substrate and drying at 170 ° C or lower. In addition, a photocatalytic film having excellent transparency and film strength is provided without performing high-temperature firing. However, as shown in the same paragraph (0061), in this example, the haze of the coating film was 0.5% to 1.0%, and the pencil hardness was 2H to 3H after heat treatment at 125 ° C. × 1 hour. It cannot be said that transparency and hardness necessary for application to a wide range of applications are sufficiently realized.

[0006]

SUMMARY OF THE INVENTION In the present invention, a transparent photocatalytic film having high hardness and excellent scratch resistance while maintaining the design and transparency of a substrate is produced by a low-cost wet method. The purpose is to provide a coating composition that can be formed.

[0007]

According to the present invention, an average particle diameter of 1 to 100 nm is obtained by stabilizing the particle surface with a chelating agent having a weight ratio of 0.1 to 2.0 with respect to a titanium compound.
A titanium compound of the general formula (1) SiX ₃ (OSi) _n X ₃ (1) (where n is 0 or an integer of 1 to 8, X is a halogen,
The alkoxy groups having 1 to 8 carbon atoms may be the same or different. A) a hydrolyzate of a hydrolyzable silicon compound represented by the formula: and a solvent, wherein the ratio of titanium to silicon is 30:70 to 90:10 (100 in total) in terms of TiO ₂ and SiO ₂ , Provided is a photocatalytic film-forming composition having a solid content of 20% by weight or less in the total composition.

[0008] The amount of the chelating agent added to the titanium compound in the titanium compound dispersion affects the balance between the dispersing effect and the liquid viscosity. If the added amount of the chelating agent is too small, a sufficient dispersing effect cannot be obtained, while if it is too large, the sol or a mixture of the sol and the hydrolyzable silicon compound hydrolyzes, resulting in thickening of the coating film. And other problems such as poor appearance. As a range that can keep the balance between the two, the amount of the chelating agent added is 0.1 to 2.0 by weight to the titanium compound.
Is preferred, but 0.1 to 1.0 is more preferred. Further, the particle size of the titanium compound affects the transparency of the coating film.
In order to impart transparency to the coating film, the particle size of the titanium compound is preferably 100 nm or less. The ratio of titanium to silicon affects the balance between the photocatalytic activity of the coating and the mechanical strength. In order to achieve both effective photocatalytic activity under actual use conditions and mechanical strength sufficient for practical use, the ratio of titanium to silicon is 30: 7 in terms of TiO ₂ and SiO ₂ .
It is preferably in the range of 0 to 90:10 (total 100). Further, the solid content concentration in the whole composition affects the transparency of the coating film. In order to obtain a transparent coating film, the solid content in the entire composition is preferably 20% by weight or less.

In the present invention, a photocatalytic film having high hardness and high wear resistance is formed while maintaining the design and transparency of the substrate. The mechanism by which a film having high transparency, high hardness, and high abrasion resistance is realized is not necessarily known, but one possibility is a weak point of a wet method film in which titanium oxide particles and a binder are mixed. It is considered that the interface between the titanium oxide and the binder is strengthened. This is to stabilize the surface of the titanium compound with a chelating agent in the state of the coating film forming composition, remove the chelating agent by heating after film formation, decomposition by a photocatalyst, etc., and increase the reactivity of the titanium compound surface. As a result, it is considered that the bonding density between the titanium compound surface inside the coating film and the binder is increased, and a strong bond is generated at the interface between the two.

In a preferred embodiment of the present invention, the particle surface is stabilized with a chelating agent having a weight ratio of 0.1 to 2.0 with respect to the titanium compound, and the average particle diameter is 1 to 100 nm.
Titanium compounds represented by the general formula _{(2) Si n O n-} 1 (OR) 2n + 2 ...... (2) ( where, n is 2 to 6, R is an alkyl group having 1 to 4 carbon atoms) represented by A lower alkyl silicate condensate, and a solvent, wherein the ratio of titanium to silicon is 30:70 to 90:10 (total 100) in terms of TiO ₂ and SiO ₂ , and the solid content concentration in the whole composition is Provided is a photocatalytic coating film forming composition that is 20% by weight or less.

According to the present invention, the lower alkyl silicate condensate represented by the general formula (2), which is a binder component, forms silica stable to the photocatalytic decomposition activity of the titanium compound by hydrolysis and condensation polymerization. I do. The component released during the condensation polymerization is only the alcohol derived from the alkoxy group of the raw material, so it evaporates during the curing process and does not hinder the densification of the coating film or the activity of the titanium compound. .

In a preferred embodiment of the present invention, the hydrolyzable silicon compound is Si (OC ₂ H ₅ ) ₄ or S
The photocatalytic coating film-forming composition according to the first or second invention is characterized by containing at least one of a condensate of i (OCH ₃ ) ₄ .

According to the present invention, silica is formed by a sol-gel method.
High density, high hardness and durability
Si (OC_Two
H_Five) _FourOr Si (OCH_Three)_FourCondensate of the binder
By using as a component, high denseness, hardness and durability
An excellent high durability photocatalytic coating film can be obtained.

In a preferred embodiment of the present invention, the chelating agent is acetylacetone, glycolic acid / lactic acid /
A first invention comprising at least one substance selected from the group consisting of α-carboxylic acids such as malic acid, β-keto esters such as methyl acetoacetate, and glycols such as ethylene glycol and hexylene glycol. To a photocatalytic coating film forming composition according to any one of the third to third inventions.

According to the present invention, acetylacetone, α-carboxylic acids such as glycolic acid / lactic acid / malic acid, β-keto esters such as methyl acetoacetate, and glycols such as ethylene glycol / hexylene glycol on the surface of the titanium compound particles. It is thought that a 5- or 6-membered ring chelate is formed with respect to the Ti atom, thereby improving the stability and dispersibility of the titanium compound.

In a preferred embodiment of the present invention, the composition for forming a photocatalytic coating film according to any one of the first to fourth inventions is applied to the surface of a substrate and cured at room temperature to 800 ° C. To provide a photocatalytic member having the photocatalytic coating film obtained as described above.

As the substrate in the present invention, glass, metal, cement, wallpaper, gypsum board, stone, ceramics, resin or the like can be considered.

According to the present invention, when cured at the same temperature, a coating film having excellent hardness and abrasion resistance can be obtained as compared with the case where a titanium compound which has been hitherto produced using an acid or an alkali is used. Because it can be formed, it is possible to form a photocatalytic coating film with higher durability without damaging the properties of the base material by heat treatment for the purpose of film curing and also on members such as buildings that can not be heat treated. I can do it.

In a preferred embodiment of the present invention, the photocatalytic coating film forming composition according to any one of the first to fourth inventions is applied to the surface of a substrate and cured at about 120 ° C. A photocatalytic member having the obtained photocatalytic coating film, wherein the surface hardness of the photocatalytic coating film is about 9H in pencil hardness.

According to the present invention, a hard photocatalytic coating film having a pencil hardness of 9H is formed at a low temperature of 120.degree. .

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below more specifically. The embodiments of the present invention are not limited to these.

The titanium compound according to the present invention exhibits an oxidizing and reducing action, and a hydrophilic action by irradiating light having energy equal to or more than a specific value, thereby generating excited electrons and holes generated by the jumping out of the electrons. A so-called titanium oxide sol or a precursor thereof, and both may be mixed. As the titanium oxide sol, crystalline titanium dioxide can be suitably used, and in particular, brookite type and anatase type are preferable. When using an amorphous titanium oxide sol, it is preferable to perform a heat treatment at a temperature or higher at which photocatalytic activity is exhibited. As the precursor, an organic titanate, a hydrotitanate, or the like, which is a precursor having a Ti—O bond, can be used. As for these precursors, those in which the condensation polymerization reaction and crystallization proceed as required during drying of the photocatalytic coating film forming composition to improve the photocatalytic activity are preferred.

These titanium compounds are in the form of fine powder, and the particle size is such that the photocatalytic activity is strong, the scattering effect to visible light is small, and the transparency is high. Because it also contributes to abrasion,
It is preferable that the size is as fine as about 100 nm or less. Further, for members such as ceramics and glass that require particularly high hardness and abrasion resistance, the particle size is preferably 30 nm or less in consideration of the balance with photocatalytic activity.
Further, when it is desired to achieve high hardness and high wear resistance, the particle size is preferably 10 nm or less.

The binder component used in the present invention is required to be a component capable of firmly binding the titanium compound particles to the base material and the titanium compound particles, and capable of withstanding the photocatalytic decomposition activity of the titanium compound. Further, in consideration of harmlessness, low cost, and availability, it is preferable that the component is a silicon dioxide component. The hydrolyzable silicon compound which is one of the starting materials is an alkyl silicate represented by the general formula (1), a silicon halide, and a condensate obtained by partially hydrolyzing these. Examples of the alkyl silicate include methyl silicate, ethyl silicate, isopropyl silicate, butyl silicate and the like, all of which are monomers or multimers formed by partial hydrolysis, that is, oligomers, and represented by the general formula (2). Is a lower alkyl silicate condensate. Particularly preferred alkyl silicates are methyl silicate and ethyl silicate, which are easily available and are considered to be easy to obtain a high hardness body during drying. These oligomers may be a mixture.

The binder component used in the present invention is preferably one obtained by using a lower alkyl silicate condensate represented by the general formula (2) as a starting material and hydrolyzing it under appropriate conditions.

As the catalyst used for hydrolyzing the alkyl silicate of the present invention, any of acid and alkali can be used. Considering the stability of the hydrolyzed binder component, the surface-treated titanium oxide sol, and the mixture thereof,
It is preferably on the acidic side. More preferably, pH
It is preferable that the area is 2 to 6. Alkyl silicates become extremely unstable when hydrolyzed with an alkali catalyst, and tend to gel, which is not preferred as the binder component of the present invention.

The alkyl silicate as a binder component in the present invention is as follows. It is preferable that the hydrolysis rate is 50 to 1500%. If an alkyl silicate having a hydrolysis rate is not used under appropriate conditions, defects are likely to occur during drying of the photocatalytic coating film forming composition, which may lead to a decrease in strength or a situation where a transparent body cannot be obtained. In addition, when the surface-treated titanium oxide sol and the binder component are mixed, it is considered that hydrolyzing in advance beforehand makes it easier to obtain a stable photocatalytic coating film forming composition.

In the present specification, the hydrolysis rate is defined as a hydrolysis rate of 100% when a ratio of 2 moles of water to 1 mole of the monomer alkyl silicate is defined as a mole ratio of the alkyl silicate and the added water. It is a parameter calculated by the ratio. Accordingly, the general formula _{(2) Si n O n-} 1
For 1 mol of the oligomeric alkyl silicate represented by (OR) _{2n + 2} , the hydrolysis rate becomes 100% by giving n + 1 mol of water.

The titanium compound whose particle surface is stabilized by the chelating agent used in the present invention is a titanium compound in which the chelating agent is chemically bonded to the particle surface. This chelating agent includes α such as acetylacetone, malic acid, glycolic acid, lactic acid, tartaric acid, gluconic acid, citric acid, and succinic acid.
-At least one substance selected from carboxylic acids, β-ketoesters such as methyl acetoacetate, and glycols such as ethylene glycol and hexylene glycol, among which substances containing α-carboxylic acid are more preferable, and among them, apples Substances containing acids are more preferred.

As a method for producing a titanium compound having a particle surface stabilized by a chelating agent, crystalline or amorphous titanium compound particles are dispersed in a dispersion medium containing a chelating agent, or titanium alkoxide, titanyl sulfate, In general, a sol is formed by mixing a precursor of a titanium compound such as titanium tetrachloride and neutralizing or hydrolyzing the mixture. For example, when using titanyl sulfate as a starting material, a method of first hydrolyzing titanyl sulfate, dispersing it with a chelating agent, and further performing a hydrothermal treatment is preferably used. Also, titanium oxide sol is suitably used. The method for producing the titanium oxide sol is not limited to these, and the titanium oxide sol may be appropriately produced by a preferred method.

The ratio of the titanium compound to the chelating agent is determined based on the balance of the dispersing effect, viscosity, hardness of the coating film and abrasion resistance of the composition. It is preferred that When the amount of the chelating agent to be added is too small, when a mixed solution of a hydrolyzate of a titanium compound and a hydrolyzable silicon compound is formed into a coating film,
The effect of improving hardness and wear resistance is reduced. In addition, if the amount is too large, a liquid in which the titanium compound is dispersed, a thickening effect occurs in a mixed solution of the hydrolyzate of the titanium compound and the hydrolyzable silicon compound, and when a coating is formed, poor appearance of the coating surface,
Problems such as a decrease in hardness and wear resistance occur.

The mixing of the components of the coating composition obtained according to the present invention is preferably carried out in the following procedure in order to maintain the dispersion stability of the titanium compound particles. First, a dispersion of titanium compound particles dispersed with a chelating agent is placed in a container, and a required amount of a solvent is added little by little to obtain a low-concentration titanium compound dispersion. To this, a hydrolyzate of a hydrolyzable silicon compound is added little by little. In order to prevent aggregation at the time of mixing and polycondensation of the hydrolyzable silicon compound, it is desirable that the liquids be kept at a constant temperature of 20 ° C. or lower and that all liquids have the same temperature.

In the present invention, the ratio between the titanium compound and the hydrolyzable silicon compound in the composition is 30:70 to 90 in terms of oxides of titanium dioxide (TiO ₂ ) and silicon dioxide (SiO ₂ ), respectively. : 10 (total 100). If the ratio of the hydrolyzable silicon compound exceeds 70%, the photocatalytic function of the titanium compound becomes small, and the practicality becomes poor. It is considered that this is because the ratio of the hydrolyzable silicon compound covering the surface of the titanium compound particles is increased, and the titanium compound is less likely to come into contact with outside air containing decomposable organic substances, water, and the like. On the other hand, if the ratio of the hydrolyzable silicon compound is 10% or less, the adhesion strength between the substrate and the titanium compound particles and between the titanium compound particles is not sufficient, and the titanium compound particles easily fall off and the film is damaged. , Making it difficult to use industrially.

In the present invention, the solid content in the composition is not more than 20% by weight. Here, the solid content concentration refers to the total amount of the titanium compound and the hydrolytic silicon compound in the entire composition, the titanium compound being TiO ₂ titanium dioxide, and the hydrolyzable silicon compound being an alkyl silicate or an alkyl silicate in the composition. Silicon (Si) in the oligomer
The value obtained by converting the component to SiO ₂ is used. Others are mainly solvents and chelating agents, whose components are mainly water and / or organic solvents and organic compounds. After the composition is applied on a substrate, it is removed by drying, thermal decomposition, photocatalytic decomposition, etc. Should be. The solid concentration is 2% by weight.
When the content is 0% or less, the composition may be set to meet various specifications such as the film thickness and the film formation method. However, when the content is more than 20%, the dispersibility of solids in the composition becomes poor, and the stability of the composition becomes poor It is remarkably reduced and gelation is likely to occur. Further, deterioration of the coating film appearance such as white turbidity and interference fringes tends to occur. Further, when the concentration is high, the film-forming properties and the adhesion between the film-formed body of the composition and the substrate are remarkably reduced, which is not preferable.

The photocatalytic coating film forming composition of the present invention more preferably has the various characteristics described above. Further, various additives may be conveniently added as desired. Specific examples include various surfactants, thickeners, dispersants, foaming agents, silane or titanium coupling agents, and dyes.

The mechanism by which the coating film obtained by the photocatalytic coating film-forming composition of the present invention has high transparency without impairing the design and transparency of the underlayer is not necessarily clear, but the excellent dispersing action of the chelating agent is not clear. Thus, it is considered that aggregation of the particles is suppressed even after the titanium compound and the binder component are mixed. It is well known that agglomeration of particles is a major factor that impairs the transparency of the coating. Also,
In a general method, the particle size of the titanium compound is set to 1 to 10
When the thickness is set to 0 nm, the scattering effect on visible light is reduced, and the solid content concentration in the entire composition is set to 20% by weight or less. The coating film forming composition is designed to increase the transparency by suppressing it.

The composition of the present invention is applied to a substrate, dried,
In some cases, it is heated and baked to form a coating film. As a coating method, a method suitable for the shape and dimensions of the substrate to be coated is conveniently used. For example, there are a brush coating, a spray method, a bar coater method, an applicator method, a spin coating method, a dipping method, a curtain wall method and the like.

In order to obtain a good balance of the hardness, abrasion resistance, photocatalytic activity, and appearance of the coating film of the composition of the present invention, the above-mentioned weight ratio of titanium dioxide and silicon dioxide in terms of oxide is required. Instead, the coating thickness is also an important factor. In the composition of the present invention, the film thickness is 10 to 10
00 nm is preferred. For specifications that emphasize transparency, 50
３００300 nm is a preferred film thickness. The film thickness should be conveniently changed according to the specification of the film.

When the composition of the present invention is cured under the same conditions, a coating having better surface hardness and abrasion resistance than a coating film using a titanium oxide compound encountered with an acid or alkali conventionally provided. A film can be formed. For this reason, there have been problems such as problems such as deterioration of the base material characteristics caused by increasing the drying conditions to the high temperature side for the purpose of improving the curability of the coating film and shortening the curing time, and high costs due to the high temperature heat treatment, which were conventionally problems. Matters can be reduced. Further, a photocatalytic coating film having excellent hardness and abrasion resistance can be formed even on a member such as a building that cannot be subjected to heat treatment at a high temperature.

As a substrate on which the composition of the present invention is applied,
Members having various shapes, such as glass, metal, cement, wallpaper, gypsum board, stone, ceramics, and resin, and composite molded articles are conceivable. When applying to these substrates, it is necessary to perform a pretreatment suitable for the substrate as well as the composition. For example, when using an organic base material such as plastic, it is necessary to coat a layer made of an inorganic substance such as silica as a block layer before coating the photocatalytic layer.

When a thin film is formed on the member surface by the above method,
The surface of the member exhibits hydrophilicity and decomposability in response to photoexcitation of a titanium compound as an optical semiconductor. Here, in order for the substrate surface to be highly hydrophilized by optical excitation of the optical semiconductor, the illuminance of the excitation light may be 0.001 mW / cm2 or more, but is preferably 0.01 mW / cm2 or more, and more preferably. Is preferably 0.1 mW / cm 2 or more. As the light source, sunlight, indoor lighting, fluorescent lamps, mercury lamps, incandescent lamps, xenon lamps, high-pressure sodium lamps, metal halide lamps, BLB lamps, germicidal lamps and the like can be suitably used. However, in the case of a thin film having a thickness of 0.1 μm or less,
It is preferable that the thin film contains a large amount of short-wavelength light of about 250 to 350 nm (preferably about 300 to 350 nm) having good absorbency.

(Effects of Photocatalyst) The photocatalyst film formed from the photocatalyst coating composition according to the present invention exhibits hydrophilicity and decomposability when irradiated with ultraviolet rays.
An anti-fogging and drip-proof effect, a surface cleaning effect such as self-cleaning property and easy cleaning property, a drying promotion effect, a deodorizing and sterilizing effect, an environmental purification effect of decomposing harmful substances in water and air, and the like can be obtained.

The substrate to which the present invention can be applied includes anti-fog,
When a drip-proof effect is expected, it is a transparent member, and glass, plastic, or the like can be suitably used for the material. Speaking of applicable base materials, mirrors such as rearview mirrors for vehicles, mirrors for bathrooms, mirrors for toilets, dental mirrors, road mirrors; spectacle lenses, optical lenses, illumination lenses, semiconductor lenses Lenses such as copier lenses, rear view camera lenses for vehicles; prisms; windows of buildings and towers; automobiles, railway vehicles, aircraft, ships, submersibles, snowmobiles, lowway gondola, amusement parks Gondolas, vehicle windows such as spaceships; cars, motorbikes, railway vehicles, aircraft, ships, submarines, snowmobiles, snowmobiles, lowway gondola, amusement park gondola, space Windshields for vehicles such as ships; protective goggles, sports goggles, protective mask shields, sports mask seals
Helmet shield, glass of frozen food display case, glass of warm food display case such as Chinese steamed bun; cover of measuring instrument, cover of camera lens for rear view confirmation for vehicle, laser Converging lenses for dental treatment devices, laser covers such as inter-vehicle distance sensors, covers for light detection sensors, covers for infrared sensors, filters for cameras, and for attaching to the surface of the article. Films, sheets, seals, patches and the like can be mentioned.

When a surface-cleaning effect is expected as a substrate to which the present invention can be applied, its material is, for example, metal, ceramic, glass, plastic, wood, stone, cement, concrete, or fiber. , Fabrics, combinations thereof, and laminates thereof can be suitably used. Speaking of applicable base materials, building materials, building exteriors, building interiors, window frames, windowpanes, structural members, vehicle exteriors and coatings, machinery and articles exteriors, dustproof covers and coatings, traffic signs, Various display devices,
Advertising towers, noise barriers for roads, noise barriers for railways, bridges, exterior and coating of garages, tunnel interiors and coatings, insulators, solar battery covers, solar water heater collector covers, vinyl houses, vehicle lighting Light covers, housing equipment, toilets, bathtubs, washbasins, lighting fixtures, lighting covers, kitchen utensils, dishes, dishwashers, dish dryers, sinks, cooking ranges, kitchen hoods
And a film, a sheet, a seal, an emblem, and the like for sticking to the surface of the article.

When a substrate to which the present invention can be applied is expected to have a drying promoting effect, the material may be, for example, metal, ceramic, glass, plastic, wood, stone, cement, concrete, fiber, Fabrics, combinations thereof, and laminates thereof can be suitably used. When the applicable substrate is used, it includes films, sheets, seals, patches, and the like to be adhered to automobile bodies, windows, pavements, and the surface of the above-mentioned articles.

The substrate to which the present invention can be applied includes deodorization,
When a sterilizing effect is expected, for example, metal, ceramic, glass, plastic, wood, stone, cement, concrete, fiber, cloth, a combination thereof, or a laminate thereof can be suitably used. . Speaking of applicable base materials, tiles, wallpaper, flooring and other interior building materials, exterior building materials, household goods in general, appliances and clothing used in nursing homes and hospitals, and films that adhere to the surface, See
And seals and patches.

When a substrate to which the present invention is applicable is expected to have an environmental purification effect, its material may be, for example, metal, ceramic, glass, plastic, wood, stone, cement, concrete, fiber, or the like. Fabrics, combinations thereof, and laminates thereof can be suitably used. Speaking of applicable base materials, water treatment materials such as beads, filters, treatment layers, interior building materials such as tiles, wallpapers, flooring, exterior building materials, roads and road materials, automobile bodies, automobile catalyst carriers,
Examples include aircraft fuselage, daily necessities, and films, sheets, seals, patches, and the like that adhere to the surface thereof.

[0048]

Example 1 29.75 g of ethanol, 3.75 g of ethyl silicate 40 (ethyl silicate pentamer, manufactured by Colcoat Co., Ltd.),
Put 5.80 g of a 2 wt% nitric acid aqueous solution into a container with a lid,
Perform hydrolysis for 5 hours while stirring in a water bath at 0 ° C.
A hydrolyzate of the silicon compound was obtained.

17.5 g of an anatase-type titanium oxide sol having a surface stabilized with malic acid having a weight ratio of 0.15 to titanium oxide and having an average particle diameter of 10 nm or less and 6 wt% of titanium oxide;
21.25 g of distilled water, hydrolyzate 1 of the above silicon compound
1.25 g was stirred to obtain a titanium oxide coating film forming composition for a photocatalyst. This composition has a ratio of titanium and silicon of 70:30 in terms of TiO2 and SiO2, and has a solid content of 3% by weight in the whole composition.

The composition was subjected to a rotation condition of 500 rpm × 2
The sample was rapidly spin-coated on a glass substrate at 1000 rpm × 20 seconds for 0 second, and kept at 120 ° C. for 1 hour to cure to obtain Sample # 1. In addition, spin coating is performed in the same manner as in # 1, and it is performed at 300 ° C. and 400 ° C. for 1 hour and a half from room temperature.
℃, 500 ℃, 300 ℃, 400 ℃, 500 ℃
Hold at 1 ℃ for 1 hour to cure, sample # 2, # 3, #
4 was obtained.

In order to evaluate the initial characteristics of the samples # 1 to # 4, the film thickness was measured by SEM. Transmittance and haze are measured by a haze meter haze-Gu manufactured by BYK-Gardner.
It was measured with ardPLUS. Table 1 shows the film thickness, transmittance, and haze.

[0052]

[Table 1]

Each film thickness was 70 nm. ♯1
# 4 In all cases, the haze is about 0.2%, and the transmittance is about 87% to 89%, which is almost the same as that of the base glass, and a good appearance with high transparency is obtained without damaging the design of the base. Was.

In order to evaluate the hardness and abrasion resistance of the sample, the pencil hardness was measured with a pencil scratch film hardness tester Model P manufactured by Toyo Seiki Seisaku-sho, Ltd. In addition, in order to evaluate the wear resistance, samples # 1 to # 4 and the glass plate used as the base material were evaluated using a rotary abrasion tester 5130 ABRAZER manufactured by Toyo Seiki Seisaku-Sho, Ltd. using a wear wheel CS-17 and a load of 2
A Taber abrasion test was performed under the conditions of 50 g and 100 rotations, and the haze before and after the test was measured with the haze meter,
The difference ΔH was used as an indicator of wear resistance. Table 2 shows the pencil hardness and the haze change ΔH before and after the Tawer wear test.

[0055]

[Table 2]

After heat treatment at a low temperature of 120 ° C., it was confirmed that Sample # 1 had a very excellent pencil hardness of 9H or more. Further, the haze change ΔH before and after the Taber abrasion test was 1.20, and it was also confirmed that the resin had extremely excellent wear resistance. Similarly, it was confirmed that Sample # 4 that had been subjected to the heat treatment at 500 ° C. had a very excellent pencil hardness of 9H or more. Further, the haze change ΔH before and after the Taber abrasion test was 0.50 in sample # 4, and it was confirmed that the sample # 4 had extremely excellent wear resistance. In the Taber abrasion test, the higher the heat treatment temperature, the lower the ΔH value of the sample, and the higher the abrasion resistance. At ♯3 and ♯4, ΔH is lower than that of sheet glass,
It was found to have very high wear resistance. Sample ♯
Although the ΔH value of 1 is slightly higher than that of glass, it has only a scratch that is not so different from glass,
It has been found that even at a heat treatment of 20 ° C., it has very high abrasion resistance, which is slightly inferior to sheet glass.

Since it was confirmed that mechanical properties such as appearance and abrasion resistance were excellent, the activity of the photocatalyst was confirmed next. First, in order to examine the hydrophilicity, samples # 1, # 2
With respect to the above, a change in the contact angle was measured by irradiating an ultraviolet ray of 0.5 mW / cm2, which is almost the same as that of outdoor ultraviolet rays, using a BLB lamp. The results are shown in FIG. It was confirmed that both the samples # 1 and # 2 were exposed to ultraviolet rays, and the contact angle of water was reduced to about 13 °, indicating that the samples had hydrophilicity.

Next, to examine the oxidative decomposition activity of the photocatalyst, samples # 1, # 2, and # 4 were vacuum
Using a photocatalyst evaluation checker PCC-1 for antifouling activity, a decomposition test of methylene blue as a blue pigment was performed. The sample which had been made hydrophilic by irradiation with ultraviolet rays in advance was immersed in a 1 mmol / l aqueous solution of methylene blue for 20 minutes, and then dried for 12 hours. The sample was irradiated with ultraviolet light, and the change in absorbance at 650 nm ΔAbs. Was measured for 120 minutes.

FIG. 2 shows the results of the evaluation of methylene blue decomposition. The greater the decrease in ΔAbs., The more methylene blue is decomposed, which means that the photocatalytic activity of the film is higher. All samples were confirmed to have oxidative degradation activity. Since the results of # 2 and # 4 were higher than # 1 due to the effect of the heat treatment, it was found that the heat treatment improved not only the wear resistance but also the photocatalytic activity.

Further, in order to examine the reduction activity of the photocatalyst,
Samples # 1 to # 4 were subjected to a silver nitrate color test. The sample was previously irradiated with ultraviolet rays of 1 mW / cm2 for 24 hours to make it hydrophilic. A 2 wt% silver nitrate aqueous solution was applied to the surface of the sample with a brush, and irradiated with ultraviolet light of 1.2 mW / cm 2 for 10 minutes, and the change in color difference was measured.

FIG. 3 shows the results of the silver nitrate color test. All the samples had reducing activity, and the activity was higher in # 2 to # 4 than in # 1 as in methylene blue, and the activity showed a maximum at # 3 at a heat treatment temperature of 400 ° C. Again, it was found that the heat treatment not only improved the abrasion resistance but also improved the photocatalytic activity.

The samples # 2 and # 3 were subjected to an oleic acid decomposition test in order to examine whether the oil required a strong decomposition activity and had a function of decomposing the oil with a photocatalyst to restore hydrophilicity. Immediately after the heat treatment, oleic acid was applied to the surface of the sample that had been hydrophilized to 5 ° C or less, gently rubbed with a sponge foamed with a neutral detergent, rinsed well with distilled water, and washed off excess oil. A thin oil film remained on the sample surface, and the contact angles of water were about 70 degrees for が 3 and about 90 degrees for ♯4. These water-repellent samples were irradiated with an ultraviolet ray of 0.5 mW / cm 2 to measure the change in the contact angle.

FIG. 4 shows the results of the oleic acid decomposition test.
In both samples # 2 and # 3, the phenomenon that oleic acid was decomposed and hydrophilized due to photocatalytic activity was observed. Especially 40
It was found that the sample which had high activity at # 3 of 0 ° C. heat treatment and had water repellency up to 70 ° C. became hydrophilic to about 10 ° C. within 20 hours, and had sufficient activity to decompose oil.

Further, in the titanium oxide sol used, it was confirmed that malic acid was adsorbed on the surface of the titanium oxide particles. In the titanium oxide sol, malic acid adsorbed on the surface of the titanium oxide particles (hereinafter referred to as adsorbed malic acid) and malic acid not adsorbed but dissolved in a solvent in a free state (hereinafter referred to as dissolved Malic acid), each of which was quantitatively evaluated. Ultrafilter the sol,
A method was employed in which malic acid contained in the filtrate was quantitatively evaluated by capillary electrophoresis.

In order to quantitatively evaluate the dissolved malic acid, the titanium oxide sol was diluted 1/100 with ultrapure water and MW 3000
Ultrafiltration at 0 gave a filtrate. Since the adsorbed malic acid maintains an adsorbed state even after ultrafiltration, this filtrate contains only dissolved malic acid. To quantitatively evaluate the adsorbed malic acid, titanium oxide sol was added to 0.1N NaO.
The mixture was diluted 1/10 with H, heated in a sealed glass bottle at 60 ° C. for 4 days, diluted 1/10 with ultrapure water, and ultrafiltered with MW 30000 to obtain a filtrate. The adsorbed malic acid is added Na
Since it is dissolved by OH, this filtrate contains both dissolved malic acid and adsorbed malic acid. Therefore, the amount of adsorbed malic acid can be determined from the difference between the malic acid contents of these two filtrates.

The quantitative analysis of malic acid in the obtained filtrate was performed by capillary electrophoresis. Inner diameter 50μm ×
104 cm long capillary and Agilent Technologies
Using an organic acid analysis buffer (pH 5.6) manufactured by Co., Ltd., electrophoresis voltage 25 kV (Negative), detection wavelength (Signal 350 nm, Referen
ce 200 nm). As a result, it was found that the sol contained 0.7% by weight of adsorbed malic acid and 0.3% by weight of free malic acid, and it was confirmed that malic acid was adsorbed on the surface of the titanium oxide particles. Was.

[0067]

According to the present invention, a low-cost wet method can be used.
It is possible to provide a coating composition that can form a transparent photocatalyst film having high hardness and excellent scratch resistance while maintaining the design and transparency of the base material.

[Brief description of the drawings]

Fig. 1 Results of hydrophilization test of samples # 1 and # 2

Fig. 2 Methylene blue decomposition test results of samples # 1, # 2, and # 4

FIG. 3 shows results of silver nitrate color test of samples # 1 to # 4

FIG. 4 shows the results of oleic acid decomposition test of samples # 2 and # 3

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01J 21/08 C03C 17/25 A 35/02 C09D 5/00 Z C03C 17/25 B01D 53/36 H C09D 5/00 ZABJ F-term (reference) 4C080 AA07 BB02 BB05 CC01 HH05 JJ06 KK08 LL03 MM02 NN06 4D048 AA21 AA22 AB01 AB03 BA06X BA07X BA41X EA01 4G059 AA01 AC30 EA04 EB05 EB06 BA04 A04 BA04A02 FA04 BD11C BE05C BE06C CA01 CA05 CA07 CA10 CA17 CD10 DA05 EB15Y EB18Y EC22Y EC27 ED02 ED04 FA01 FA03 FB23 FC02 FC07 FC08 4J038 DL021 NA06 PA18 PA19 PB01 PB02 PB05 PB06 PB07 PB08 PB09 PC02 PC03 PC04 PC06

Claims (6)

[Claims] (1) a weight ratio of 0.1 to 2.
The average particle diameter of the particle surface stabilized with a chelating agent of 0 to 1
100 nm titanium compound, general formula (1) SiX3 (OSi) nX3 (1) (where n is 0 or an integer of 1 to 8, X is halogen,
The alkoxy groups having 1 to 8 carbon atoms may be the same or different. A) a hydrolyzate of a hydrolyzable silicon compound represented by the formula: and a solvent, wherein the ratio of titanium to silicon is 30:70 to 90:10 (100 in total) in terms of TiO ₂ and SiO ₂ , A photocatalytic coating film forming composition having a solid content concentration of 20% by weight or less in the whole composition. 2. A weight ratio of 0.1 to 2.
The average particle diameter of the particle surface stabilized with a chelating agent of 0 to 1
Titanium compound 100 nm, the general formula _{(2) Si n O n-} 1 (OR) 2n + 2 ...... (2) ( where, n is 2 to 6, R is an alkyl group having 1 to 4 carbon atoms) represented by A lower alkyl silicate condensate, and a solvent, wherein the ratio of titanium to silicon is 30:70 to 90:10 (100 in total) in terms of TiO ₂ and SiO ₂ , and the solid content concentration in the whole composition Is 20% by weight or less. Wherein said hydrolyzable silicon compound, Si, characterized in that it includes at least one of (OC ₂ H _{5) 4} or Si (OCH _{3) 4} condensates of claim 1 or 2 Photocatalytic coating film forming composition. 4. The chelating agent is selected from the group consisting of acetylacetone, α-carboxylic acids such as glycolic acid / lactic acid / malic acid, β-keto esters such as methyl acetoacetate, and glycols such as ethylene glycol / hexylene glycol. The photocatalytic coating film forming composition according to any one of claims 1 to 3, further comprising at least one substance. 5. A photocatalytic coating film obtained by applying the photocatalytic coating film forming composition according to any one of claims 1 to 4 to a surface of a substrate and curing at room temperature to 800 ° C. A photocatalytic member. 6. A photocatalytic coating film obtained by applying the photocatalytic coating film forming composition according to any one of claims 1 to 4 to a surface of a substrate and curing at about 120 ° C. A photocatalytic member in which the surface hardness of the photocatalytic coating film is about 9H in pencil hardness.