JPH11228865A - Coating agent for forming photocatalytic hydrophilic coating film and photocatalytic hydrophilic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject coating agent capable of forming a titanium oxide coating film excellent in film hardness, abrasion resistance and photocatalytic hydrophilizing actions and useful for a window glass, or the like, for vehicles and buildings by adding a very small amount of a specific silicon compound to an amorphous type titania precursor. SOLUTION: This coating agent contains (A) a precursor of an amorphous type titania [concretely, an organotitanium compound such as a titanium alkoxide, a chelate or an acetate or an inorganic titanium compound such as TiCl4 or Ti(SO4 )2 ] and (B) a silicon alkoxide (hydrolyzate) [e.g. a tetraalkoxysilane (hydrolyzate), an alkyl silicate (hydrolyzate) or a polysiloxane having <=3,000 average molecular weight]. The coating agent preferably contains the component B in an amount of 0.1-10 mol.% based on the total amount of the components A and B and expressed in terms of the oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating agent for forming a photocatalytic hydrophilic film using crystalline titanium oxide, and relates to a heat-resistant base material, in particular, a window glass, a cover glass,
The present invention relates to articles requiring high abrasion resistance suitable for automobile mirrors and the like. Here, the heat-resistant substrate is mainly a glass that does not thermally deform even when heat-treated in the above temperature range, but also includes the following substrates. Quartz glass or the like that can be heat-treated at a high temperature of 600 ° C. or higher because of its high heat deformation temperature.
Includes those that are intentionally thermally deformed at a temperature exceeding 0 ° C., and those that are thermally strengthened at about 800 ° C. to enhance impact resistance.

[0002]

_2. Description of the Related Art Conventionally, a method for producing a hydrophilic film mainly composed of TiO ₂ involves a method in which a titanium alkoxide is used as a starting material as described in WO 96-29375 and a solution of the same is applied to a substrate such as glass. A method of applying and baking at about 500 ° C. is described. This titanium alkoxide is
In addition to alkoxides such as tetraethyl titanate and isopropyl titanate, a hydrolyzate obtained by adding an acid and water and diluting with alcohol, Nippon Soda which has improved the stability of such a hydrolyzed solution ( Atron NTi500
And NTD90. Conventionally, composite oxides of titanium and silicon have been used as low-expansion glass. For example, Kamiya, Sakuhana et al., "The Chemical Society of Japan, No. 10, p1571, (1981), Ceramic Association. Paper, 90 [6], 328, (1981) "discloses a method for producing titanium alkoxide and silicon alkoxide as starting materials.

[0003]

An object of the present invention is to provide an alkoxide-derived TiO ₂ coating having a high film hardness. When an organic chelate compound of Ti represented by an alkoxide is used, a transparent and uniform coating can be easily obtained. Under a thin film condition of 50 nm or less, a very hard film can be easily obtained. However, as the film thickness is increased to about 100 nm, the hardness decreases, and the film formation atmosphere and firing conditions need not be strictly controlled. Thus, it was difficult to obtain a high hardness coating. Further, in the prior art for producing a composite oxide of titanium and silicon, a catalyst preparation using a metal alkoxide, IPC, (1993), p33
7), a silicon alkoxide and / or a hydrolyzate thereof are added in a large amount to a titanium alkoxide or a hydrolyzate thereof, so that a Ti—O—Si bond having high homogeneity in an alkoxide solution is used. Occurs,
The crystallization of TiO ₂ was suppressed, the crystallization of titanium oxide was suppressed, and super-hydrophilicity could not be exhibited.

[0004]

According to the present invention, a titanium alkoxide and / or a hydrolyzate thereof is added with a trace amount of a silicon alkoxide and / or a hydrolyzate thereof to form a TiO ₂ coating formed using the alkoxide and / or the hydrolyzate thereof. Film hardness,
It has improved wear resistance. Titanium alkoxide is a starting material for forming titanium oxide crystallized from a solution through heat treatment, and has a function of developing photocatalytic hydrophilicity and a role of forming a dense and strong film. Those forming the same crystalline titanium oxide include chelates, or organic titanates such as acetate, or TiCl
A precursor of amorphous titania may be a generic term for inorganic titanium compounds such as ₄ or Ti (SO ₄ ) ₂ .

Although the function of the present invention has not been fully elucidated, the present inventors consider the main function as follows. Since silicon alkoxide has an effect of suppressing crystallization of titania, the inventors of the present invention have found that, by the optimal addition according to the present invention, a grain boundary of crystalline titania is networked to form a dense film. ,thinking. In addition, unlike the conventional composite oxide production technology of titanium and silicon, TiO ₂ is crystallized at the time of firing to exhibit photocatalytic hydrophilicity by adding only a small amount of silicon alkoxide and / or its hydrolyzate. It is thought that it came to do.

[0006]

Next, a specific configuration of the present invention will be described. The precursor of amorphous titania in the present invention is an alkoxide, chelate, or an organic titanium compound such as acetate, or TiCl ₄ or Ti (SO ₄ ) _2.
Such inorganic titanium compounds are generically referred to. Further, the titanium alkoxide in the present invention, for example, tetraethoxytitanium, tetraisopropoxytitanium, tetra n-propoxytitanium, tetrabutoxytitanium, tetramethoxytitanium, and the like, and they include a hydrolysis inhibitor such as hydrochloric acid or ethylamine. Is added and diluted with an alcohol such as ethanol or propanol, and then a (partial) hydrolyzate is produced with partial or complete hydrolysis. These amorphous titanias are applied to the surface of the substrate, and the temperature is adjusted to 200 from normal temperature ^. Hydrolysis and dehydration polycondensation at the temperature of C generate titanium hydroxide, and a layer of amorphous titania is formed on the surface of the substrate by dehydration polycondensation of titanium hydroxide. Next, the amorphous titania is changed into crystalline titania by heating to a temperature higher than the crystallization temperature of titania and lower than the softening point of the substrate.

The silicon alkoxide and / or its hydrolyzate in the present invention includes, for example, tetraalkoxysilane such as tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetrabutoxysilane, tetramethoxysilane and / or the like. Or a hydrolyzate thereof, or a mixture of an alkyl silicate such as ethyl silicate or methyl silicate and / or a hydrolyzate thereof, or a polysiloxane having an average molecular weight of 3000 or less.

[0008] Photocatalytic hydrophilicity is described in WO 96/2937.
As disclosed in No. 5, the property of exhibiting hydrophilicity in response to photoexcitation, when titania is photoexcited by ultraviolet light, water is chemically adsorbed on the surface in the form of hydroxyl groups (OH ⁻ ) by photocatalysis, and as a result It is believed that the surface becomes superhydrophilic. Since this photocatalytic hydrophilicity is excited by a light source having an energy greater than the band gap of the photocatalyst,
Anatase titania has a wavelength of 387 nm or less, rutile titania has a wavelength of 413 nm or less, tin oxide has a wavelength of 344 nm or less, and zinc oxide has a wavelength of 387 n.
It can be photoexcited with ultraviolet light of m or less. for that reason,
As the ultraviolet light source suitable for the present invention, an indoor illumination lamp such as a fluorescent lamp, an incandescent lamp, a metal halide lamp, and a mercury lamp can be used. The anti-fog glass, lens and mirror are exposed to ultraviolet light, and the surface is made superhydrophilic by photoexcitation of the photocatalyst. Under conditions of exposure to sunlight, such as a vehicle rearview mirror, the photocatalyst is advantageously naturally photoexcited by the ultraviolet light contained in the sunlight.

The photoexcitation can be carried out or can be carried out until the contact angle of the surface with water is less than about 10 °, preferably less than about 5 °, especially about 0 °. Generally, 0.00
If photoexcitation is performed with an ultraviolet illuminance of 1 mW / cm ² , super hydrophilicity can be achieved in a few days until the contact angle with water becomes about 0 °.
The illuminance of ultraviolet rays contained in sunlight falling on the surface of the earth is about 0.
Since it is 1 to 1 mW / cm ² , the surface can be made superhydrophilic in a shorter time if exposed to sunlight. For self-cleaning (self-cleaning) of the surface of the base material by rainfall or prevention of attachment of contaminants, a photocatalytic coating can be formed with a photocatalyst capable of photoexcitation with ultraviolet light or visible light. Articles coated with the photocatalytic coating are placed outdoors and exposed to sunlight and rain. Once the surface has been highly hydrophilized, the hydrophilicity persists at night. The hydrophilicity is restored and maintained each time it is again exposed to sunlight.

When providing a substrate coated with the photocatalytic coating of the present invention to a user, it is desirable to previously make the photocatalytic coating superhydrophilic. The method for applying to the substrate in the present invention may be appropriately selected, and for example, methods such as spray coating, dip coating, flow coating, spin coating, roll coating, brush coating, and sponge coating are preferably used. Available. In the present invention, the addition amount of the silicon alkoxide and / or the hydrolyzate thereof is preferably 0.1 to 10 mol%, more preferably 1 to 10 mol% in terms of oxide, based on the total alkoxide and / or the hydrolyzate thereof. 8 mol%, and more preferably,
2 to 5 mol%. The reason is that by adding silicon alkoxide and / or its hydrolyzate, a dense film can be formed to network the grain boundaries of crystalline titania. The wear resistance is improved. On the other hand, when the addition amount of the silicon alkoxide and / or the hydrolyzate thereof is too large, a highly homogeneous Ti—O—Si bond occurs in the alkoxide solution,
This is because crystallization of TiO ₂ is suppressed and super hydrophilicity cannot be exhibited.

The heat-resistant substrate to which the present invention can be used includes:
Glass, ceramics, metals and the like are preferred. There are many kinds of glass such as soda lime glass for construction, quartz glass, non-alkali glass, low expansion glass and crystallized glass. Ceramics having a glaze layer such as a glazed tile are preferable. The heat resistance in the present invention,
It mainly refers to a temperature at which the base material does not deform, and heat treatment of the base material in that temperature range promotes crystallization of titania.
For example, in the case of soda lime glass, it is applied in a temperature range of 400 to 600 ° C. because it softens when it exceeds 600 ° C. However, there is also a special application method in which thermal deformation is intentionally performed at a temperature exceeding 600 ° C. to create a curved mirror, or thermal strengthening is performed at about 800 ° C. to enhance impact resistance. On the other hand, since quartz glass does not thermally deform even at temperatures exceeding 600 ° C., heat treatment can be performed at a higher temperature, and a dense film having high wear resistance can be obtained.

Preferred substrates to be applied include window glass for vehicles or window glass for general construction, skylights, bay windows, and the like.
Fixed windows, curtain walls, top lights, etc.
Alternatively, mirrors such as vehicle mirrors and bathroom mirrors, cameras, sensors, cover glasses such as solar cells, and lighting fixtures such as fluorescent lamps and light bulbs can be suitably used. According to another preferred embodiment of the present invention, a surfactant,
It may contain an acid, a hydrolysis catalyst, a polymerization curing catalyst, a leveling agent, an antibacterial metal, a platinum group metal, and a pH adjuster.
According to another preferred embodiment of the present invention, the composition according to the present invention may further comprise a surfactant. The addition of surfactants can impart a high degree of hydrophilicity and anti-fog properties to the applied surface even immediately after the application of the composition according to the invention. Particularly when the composition according to the invention comprises an alcohol, its addition is preferred.
The hydrophilization of the surface to which the composition according to the invention has been applied by light irradiation can take several hours in some cases. At this time, if alcohol derived from the composition according to the present invention remains on the surface, the surface may not be sufficiently hydrophilized until hydrophilization by the photocatalyst is obtained. The addition of the surfactant is preferable because the surface can be sufficiently hydrophilized and the antifogging property can be imparted even immediately after the application of the composition. Furthermore, the addition of a surfactant has the advantage that the composition according to the invention can be applied homogeneously to the surface of the component.

In a preferred embodiment of the present invention, the surfactant is preferably added in an amount of less than 10 parts by weight, more preferably about 0.1 to 2 parts by weight, based on 1 part by weight of the photocatalyst particles. Examples of surfactants that can be added to the composition according to the present invention include sulfonic acid polyoxyethylene alkyl phenyl ether ammonium salt, sulfonic acid polyoxyethylene alkyl phenyl ether sodium salt, fatty acid sodium soap, fatty acid kali soap,
Sodium dioctyl sulfosuccinate, alkyl sulfate, alkyl ether sulfate, alkyl sulfate soda salt, alkyl ether sulfate soda salt, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether sulfate soda salt, alkyl sulfate TEA salt, polyoxyethylene alkyl ether sulfate TEA salt, 2-
Ethylhexyl alkyl sulfate sodium salt, sodium acylmethyltaurate, sodium lauroylmethyltaurate, sodium dodelsylbenzenesulfonate, disodium lauryl sulfosuccinate, disodium lauryl polyoxyethylene sulfosuccinate,
Polycarboxylic acid, oleoyl sarcosine, amide ether sulfate, lauroyl sarcosine, sulfo F
Anionic surfactants such as sodium salt of A ester; polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether, polyoxyethylene Oxyethylene alkyl ester, polyoxyethylene alkyl phenol ether,
Polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene laurate, polyoxyethylene stearate, polyoxyethylene alkyl phenyl ether, polyoxyethylene oleate, sorbitan alkyl ester,
Polyoxyethylene sorbitan alkyl ester, polyether modified silicone, polyester modified silicone, sorbitan laurate, sorbitan stearate,
Sorbitan palmitate, sorbitan oleate, sorbitan sesquioleate, polyoxyethylene sorbitan laurate, polyoxyeletin sorbitan stearate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan oleate, glycerol stearate, polyglycerin fatty acid ester , Alkylalkylolamide, lauric acid diethanolamide, oleic acid diethanolamide, oxyethylene dodecylamine, polyoxyethylene dodecylamine, polyoxyethylene alkylamine, polyoxyethylene octadecylamine, polyoxyethylene alkylpropylenediamine, polyoxyethyleneoxy Nonionic surfactants such as propylene block polymer and polyoxyethylene stearate Agent; dimethyl alkyl betaine,
Amphoteric surfactants such as alkylglycine, amidobetaine and imidazoline, octadecyldimethylbenzylammonium chloride, alkyldimethylbenzylammonium chloride, tetradecyldimethylbenzylammonium chloride, dioleyldimethylammonium chloride, 1-hydroxyethyl-2-alkylimidazoline quaternary Salt, alkylisoquinolinium bromide,
Polymeric amine, octadecyltrimethylammonium chloride, alkyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, behenyltrimethylammonium chloride, alkylimidazoline quaternary salt, dialkyldimethylammonium chloride, octadecylamine acetate, tetradecylamine acetate And cationic surfactants such as salts, alkyl propylene diamine acetate, and didecyl dimethyl ammonium chloride.

According to a preferred embodiment of the present invention, the composition according to the present invention may contain an acid. The addition of this acid increases the polarity of the surface to which the composition according to the present invention is applied, and can maintain good hydrophilicity even in a dark place. Examples of acids that can be added to the composition according to the present invention include nitric acid, sulfuric acid, hydrochloric acid, acetic acid, propionic acid, maleic acid, adipic acid, fumaric acid, phthalic acid, and valeric acid, which have a large ability to impart polarity to the surface. Lactic acid, butyric acid, citric acid, malic acid, picric acid, formic acid, carbonic acid, phenol and the like. Particularly, nitric acid, hydrochloric acid and sulfuric acid are preferred.

According to another preferred embodiment of the invention, the composition according to the invention may comprise a silane hydrolysis catalyst. The presence of this catalyst promotes the hydrolysis of the silane compound as a precursor in the method for applying the composition according to the present invention described below. Examples of preferred catalysts include nitric acid, sulfuric acid, hydrochloric acid, acetic acid, propionic acid, maleic acid, adipic acid, fumaric acid, phthalic acid, valeric acid, lactic acid, butyric acid, citric acid, malic acid, picric acid having a pH of 2 to 5. Formic acid, carbonic acid, phenol and the like.

According to another preferred embodiment of the present invention, the composition according to the present invention, when the silica precursor is silanol, can comprise a polymerization curing catalyst for silanol. The presence of the catalyst promotes the polymerization reaction of silanol in the method for applying the composition according to the present invention described below. Preferred examples of the catalyst include aluminum compounds such as aluminum chelate, aluminum acetylacetonate, aluminum perchlorate, aluminum chloride, aluminum isobutoxide, and aluminum isopropoxide; titanium compounds such as tetraisopropyl titanate and tetrabutyl titanate; Basic compounds such as lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium methylate, sodium acetate, sodium formate, potassium acetate, potassium formate, potassium propionate, tetramethylammonium chloride, tetramethylammonium hydroxide; n-hexylamine, tributylamine, diazabicycloundecene, ethylenediamine, hexanediamine, diethylenetriamine, tetraethylene Tertamine, triethylenetetramine, ethanolamines, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, γ- (2-aminoethyl) -aminopropyltrimethoxysilane, γ- (2-aminoethyl)- Amine compounds such as aminopropylmethyldimethoxysilane; tin compounds such as tin acetylacetonate and dibutyltin octylate; metal-containing compounds such as cobalt octylate, cobalt acetylacetonate and iron acetylacetonate; phosphoric acid; Examples include acidic compounds such as nitric acid, phthalic acid, p-toluenesulfonic acid, and trichloroacetic acid.

According to a preferred embodiment of the present invention, the composition according to the present invention may comprise a leveling agent so that a smooth surface can be formed when applied to the surface of the member. The addition of a leveling agent is particularly advantageous when applying the composition according to the invention to large articles.
Preferred examples of the leveling agent include diacetone alcohol, ethylene glycol monomethyl ether, 4-hydroxy-4-methyl-2-pentanone, dipropylene glycol, tripropylene glycol, 1-ethoxy-2-propanol, and 1-butoxy-2. -Propanol, propylene glycol monomethyl ether, 1-propoxy-2-propanol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monoethyl ether and the like.

According to a preferred embodiment of the invention, the composition according to the invention comprises an antimicrobial metal (eg Ag, Cu, Z
n) or a compound thereof. By the addition of these metals it is possible to kill bacteria present on the surface when applying the composition according to the invention,
Furthermore, even after application, growth of microorganisms such as mold, algae, and moss on the surface can be suppressed. According to yet another preferred embodiment of the present invention, a composition according to the present invention comprises:
It can comprise at least one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, Ru, Os, and Ir. The surface having a photocatalyst composed of a metal oxide has an antifouling, antibacterial,
It is known to have a deodorant function. It seems that this effect is maintained even on the surface of the member to which the composition according to the present invention is applied. It is considered that the metal enhances the oxidative decomposition action of the photocatalyst and improves the antibacterial property, deodorizing property, gas decomposability, organic substance decomposability, and the like of the surface.

The composition according to the present invention is preferably weakly acidic, neutral or basic when stored in a tin container or a container made of lining metal, or when applied on a metal member. Particularly when an acid is added as described above, it is preferable to add a pH adjuster. Further, the coating agent of the present invention has excellent abrasion resistance even when coated on a thick film having a thickness of 50 nm or more. Preferably, a film having a thickness of 200 nm or more, more preferably 500 nm or more, can be provided that has both abrasion resistance and photocatalytic hydrophilicity. If it can be coated on a thick film of 50 nm or more, it can have excellent redox activity,
Functions such as decomposition and deodorization can also be improved. However, from the viewpoint of abrasion resistance, it is better to be thin to some extent, and it is preferable that the thickness is 1 μm or less. In addition, the composition according to the present invention can appropriately contain an acid or a base in order to improve the dispersibility of the solid component contained and to improve the storage stability. Further, it may optionally contain pigments, dyes, storage stabilizers and the like.

In the case of application to a soda lime glass substrate in the present invention, the provision of the intermediate layer can sufficiently exhibit photocatalytic hydrophilicity. When the base material is glass or glazed tile containing alkali network modifying ions such as sodium, it is preferable to form an intermediate layer such as silica in advance between the base material and the amorphous titania layer. This prevents the alkali network modifying ions from diffusing from the substrate into the photocatalytic coating during firing of the amorphous titania, and achieves a super hydrophilic property such that the contact angle with water becomes 0 °. .

[0021]

Example Preparation of Solution NTD90 manufactured by Nippon Soda for forming a TiO ₂ film was diluted with a mixed solvent of ethyl acetate and EtOH to a solid concentration of 4% in terms of oxide to obtain a titanium alkoxide solution A.
Next, NSi manufactured by Nippon Soda to form a SiO ₂ coating
500 was diluted with a mixed solvent of ethyl acetate and EtOH to a solid concentration of 4% in terms of oxide to obtain a silicon alkoxide solution B. Further, in 86 parts by weight of a solvent of ethanol, 6 parts by weight of tetraethoxysilane Si (OC2H5) 4 (Wako Pure Chemical, Osaka), 6 parts by weight of pure water, and 2 parts by weight of 36% hydrochloric acid as a hydrolysis inhibitor for tetraethoxysilane Was added and mixed to prepare a silicon alkoxide solution C. Since the solution generated heat by mixing, the mixture was left to cool for about 1 hour. Finally, a mixture of 1 part by weight of tetraethoxytitanium Ti (OC ₂ H ₅ ) ₄ (Merck) and 9 parts by weight of ethanol was added as a hydrolysis inhibitor to the mixture.
% Titanium chloride was added to prepare a titanium alkoxide solution D. The following examples were made based on these solutions.

Example 1 After sufficiently mixing the solution A and the solution B so that the molar ratio of TiO ₂ : SiO ₂ = 98: 2 in terms of oxide, the core for forming a photocatalytic hydrophilic film of Example 1 was used. Ting agent. Next, a washed 2 mm thick glass plate was prepared, and NSi500,
It is immersed in a 5% solution and pulled up at a speed of 24 cm / min.
Drying at ℃ gave a SiO ₂ coating. The solution of Example 1 was similarly immersed on this SiO ₂ coat glass, pulled up, dried, and fired at 500 ° C. to obtain a photocatalytic hydrophilic film of Example 1. Also. The reason for providing an intermediate layer of SiO ₂ is disclosed in
-5075 from glass as described in
During the heat treatment at 0 ° C., alkali ions such as Na ⁺
This is because it diffuses into the O ₂ film and suppresses crystallization of TiO ₂ .

Examples 2 to 4 As shown in Table 1, the amount of solution B was adjusted to 3, 4, and 5 mol%, and after mixing with solution A in the same manner as in Example 1,
To 4 coating agents for forming a photocatalytic hydrophilic film. Example ₂ An intermediate layer of SiO ₂ was provided in the same manner as in Example 1.
~ 4 photocatalytic hydrophilic coatings were obtained.

[0024]

[Table 1]

Comparative Example 1 Using the solution A as the coating agent of Comparative Example 1, an intermediate layer of SiO ₂ was provided in the same manner as in Example 1 to obtain a photocatalytic hydrophilic film of Comparative Example 1.

Comparative Example 2 Solution A was diluted to a solid concentration of 1.6%.
A photocatalytic hydrophilic film of Comparative Example 2 was obtained by providing an intermediate layer of SiO ₂ as in Example 1 as a coating agent.

COMPARATIVE EXAMPLE 3 90 parts by weight of solution A and 10 mol% of solution B were mixed well and then mixed well. As a coating agent of comparative example 3, an intermediate layer of SiO ₂ was provided in the same manner as in example 1. 3 was obtained. All of the coatings except Comparative Example 2 described above had a thickness of about 90 nm. For Comparative Example 2, the film thickness was about 30
nm. Their hydrophilic performance and abrasion resistance were evaluated. As for the hydrophilicity performance, a hydrophilicity reaching angle and a dark place maintenance were evaluated. The reaching angle of hydrophilization, after hydrophobizing the superhydrophilic coating, to test whether the hydrophilicity is restored by UV irradiation, after attaching oleic acid to the surface,
After washing with a neutral detergent and washing with water and drying, a 20 W Sankyo Denki black light blue lamp (abbreviated as BLB) is used for 10 c.
m and a contact angle of a water droplet after 4 hours was determined. The determination of hydrophilicity is performed based on this contact angle. In the order of high hydrophilicity performance, less than 8 ° is ◎, less than 15 ° is 、, 25 °
Less than △ and △ 25 ° or more. From the experience of the present inventors, in order to exhibit anti-fogging properties, it is necessary that ◎ be less than 8 °, and the droplet performance when applied to an automobile mirror or the like is as follows:
It is considered that a contact angle of less than 25 ° in the judgment and desirably less than 15 ° in the judgment of ○ is required. Table 1 shows the hydrophilic performance and the coating agent composition evaluated by such a method. Examples 1 to 4 and Comparative Examples 1 and 2 all became hydrophilic to less than 5 ° after light irradiation, and showed extremely high hydrophilicity. However, Comparative Example 3, in which a large amount of silicon alkoxide was added, did not decrease to 25 ° or less even after light irradiation, and did not become hydrophilic.

Next, Table 2 shows the pencil hardness. JIS K5
According to 400, evaluation was made by a scratching method.

[0029]

[Table 2]

Comparative Example 2 in which the film thickness was small, and Examples 1-4 in which silicon alkoxide was added in the thick film condition.
And, in Comparative Example 2, the pencil hardness was 4H or more, showing very high abrasion resistance. However, in Comparative Example 1 in which the silicon alkoxide was not added under the condition of a thick film, the pencil hardness was as low as 3B, which was not suitable for a part requiring abrasion. Next, the effect of suppressing the crystallization of TiO ₂ by adding silicon alkoxide was examined based on the intensity of the strongest line of anatase X-ray diffraction. Table 3 shows the results.
Shown in

[0031]

[Table 3]

Example 5 Solution C and Solution D were converted to oxides with TiO ₂ : SiO ₂ = 9.
The mixture was mixed at a molar ratio of 8: 2, dried in an evaporating dish, pulverized, placed in a crucible and heat-treated at 450 ° C.

EXAMPLE 6 In the same manner as in Example 5, the solution C and the solution D were prepared by converting TiO2 into oxide.
_The mixture was mixed in a molar ratio of ₂ : SiO ₂ = 95: 5, dried in an evaporating dish, pulverized, placed in a crucible and heat-treated at 450 ° C.

Comparative Example 4 Only solution C was dried in an evaporating dish, pulverized, and placed in a crucible and heat-treated at 450 ° C.

[0035] TiO terms of oxide of the solution C and solution D in the same manner as in Comparative Example 5 Example 5
₂ : SiO ₂ = 90: 10 molar ratio,
After drying in an evaporating dish, pulverize and put in a crucible at 450 ° C
Was heat-treated. As can be seen from the X-ray analysis results in FIG.
In Examples 5 and 6, and Comparative Example 3, the strongest line of anatase was observed by shaping and was more than 1500 counts.
It was confirmed that it was crystallized. On the other hand, in Comparative Example 4, only a weak peak of about 200 counts was observed, indicating that crystallization was greatly suppressed.

[0036]

According to the present invention, a photocatalytic hydrophilic film having high abrasion resistance can be provided.
There is an effect that can be widely applied to a portion that receives sliding. Furthermore, since the thickness of this coating can be increased, a coating exhibiting high photocatalytic decomposition power and exhibiting hydrophilicity can be provided.

[Brief description of the drawings]

FIG. 1 shows the result of X-ray analysis of the composition of the present invention.

Claims (10)

[Claims] 1. A coating agent for forming a photocatalytic hydrophilic film, comprising a precursor of amorphous titania and a silicon alkoxide and / or a hydrolyzate thereof. 2. A coating agent for forming a photocatalytic hydrophilic film, comprising a titanium alkoxide and / or a hydrolyzate thereof and a silicon alkoxide and / or a hydrolyzate thereof. 3. A silicon alkoxide and / or a hydrolyzate thereof is added in an amount of 0.1 to 10 mol% in terms of oxide based on a total amount of an amorphous titania precursor and a silicon alkoxide and / or a hydrolyzate thereof. The coating agent for forming a hydrophilic film according to claim 1, characterized in that: 4. The method according to claim 1, wherein the silicon alkoxide and / or the hydrolyzate thereof are added in an amount of 1 to 8 mol% in terms of oxide based on the total amount of the amorphous titania precursor and the silicon alkoxide and / or the hydrolyzate thereof. The coating agent for forming a hydrophilic film according to claim 1. 5. The method according to claim 2, wherein the silicon alkoxide and / or the hydrolyzate thereof is added in an amount of 0.1 to 10 mol% in terms of oxide based on all alkoxides and / or hydrolysates thereof. For forming a hydrophilic film
Ting agent. 6. The hydrophilic composition according to claim 2, wherein the silicon alkoxide and / or the hydrolyzate thereof is added in an amount of 1 to 8 mol% in terms of oxide based on the total alkoxide and / or the hydrolyzate thereof. Coating agent for film formation. 7. A photocatalytic hydrophilic member, wherein the coating agent according to claim 1 is applied to the surface of a substrate. 8. A photocatalytic hydrophilic member, wherein the coating agent according to claim 1 is applied to the surface of a heat-resistant base material and heat-treated at a temperature of 400 ° C. to 800 ° C. 9. The photocatalytic hydrophilic member according to claim 7, wherein the heat-resistant substrate is glass. 10. A titanium oxide film having a thickness of 0.05 μm to 1
The photocatalytic hydrophilic member according to any one of claims 7 to 9, wherein the thickness is set to be μm.