JP3300940B2 - Method of forming underlayer for photocatalytic film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base for a photocatalytic film.
Those concerning the formation how the film.

[0002]

2. Description of the Related Art In recent years, application to applications such as deodorization, antibacterial, antifungal and antifouling utilizing the effect of titanium dioxide has been studied. As an example of a method of fixing titanium dioxide (titania) to a substrate, a sol obtained by hydrolyzing / polycondensing titanium alkoxide or titanium tetrachloride is applied to a substrate having high heat resistance and dried. After that, there is a method of heat treatment, a method of dispersing titanium dioxide particles in water or alcohol, applying it to a substrate, drying it, and sintering the particles attached to the surface of the substrate.

On the other hand, when applied to a substrate having low heat resistance, a fluororesin or silicone resin having relatively excellent light resistance is used as a binder for titanium dioxide. When applying a photocatalytic film to a plastics substrate, a barrier layer should be provided between the plastics and the film containing titanium dioxide to prevent the plastics from directly coming into contact with titanium dioxide and being decomposed. Is common. Further, when the base material is soda lime glass, it is necessary to apply a base film to the base material as a barrier layer in order to prevent sodium from diffusing into the photocatalytic film when the photocatalytic film is baked and the photocatalytic activity being reduced. General.

[0004] As properties of the base film, inside a dense, itself no photocatalytic effects it is necessary to not degraded by the photocatalyst, inorganic or silicone resin such as SiO _2, light resistance resin such as a fluororesin Is generally used as a base film.

Also, a sol using a sol obtained by hydrolysis of a metal alkoxide and subsequent condensation polymerization is used.
It is known that the gel method can be fired at low temperature and can form an inorganic film on various substrates with good adhesion. In the sol-gel method, a methyl group is directly bonded to Si.
It is known that, if a functional alkoxide is used, a film excellent in processability can be obtained because a methyl group remains in the film (for example, the Ceramic Society of Japan 97,
[1], pp. 91-94, 1989).

[0006]

However, when a film made of an inorganic powder is used as a base film, high-temperature sintering is required in order to sinter the powder, and therefore, it can be applied only to a substrate having high heat resistance. There is a problem that the base material is limited because it cannot be performed and the workability is poor.

On the other hand, when a silicone resin or a fluororesin is used as a base film, pre-coating is possible because the workability is superior to that of an inorganic material. The poor adhesion when applying a photocatalyst film to a substrate often requires an adhesion layer between the base film and the photocatalyst film. There is a problem that the blast treatment is performed on the base material or an adhesive layer is required between the base material and the base film.

When a fluororesin or a silicone resin is used as a base film, a photocatalytic film can be applied to a substrate having a low heat-resistant temperature. However, there is a problem that the light resistance is not sufficient depending on the application because the methyl group contained in the resin is decomposed by the photocatalyst at the interface between the photocatalytic film as the upper coating film and the silicone resin film as the base film.

In the sol-gel method, if a trifunctional alkoxide in which a methyl group is directly bonded to Si is used, a film excellent in adhesion to a substrate, workability, and light resistance can be obtained, but the surface of the film is excellent. When a hydrophilic photocatalyst-forming sol is applied to this film, the coating is repelled and there is no unevenness on the surface, so that there is a problem that mechanical adhesion cannot be expected.

As described above, the sol-gel method is excellent in that it can be fired at a low temperature, can apply an inorganic film to various substrates with good adhesion, and can form a film having excellent workability. There has been a problem that a dense inner layer required as a barrier layer applied between the photocatalyst film and the substrate and a rough surface layer for applying the photocatalyst film with good adhesion cannot be formed at the same time.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a sol obtained by hydrolyzing and polycondensing a silicon alkoxide having a methyl group directly bonded to Si in the presence of SiO ₂ particles. A photocatalyst with excellent adhesion to the substrate obtained by applying it to any substrate and drying or baking after drying, adhesion to the photocatalytic film as an overcoat film, excellent workability and a dense inner layer and a rough surface layer Base for coating
In the attempt to provide the formation how the film.

[0012]

In order to achieve the above object, a method for forming a base film for a photocatalytic film according to the present invention comprises:
R ¹ nSi (OR ² ) _4-n (where R ¹ is alkyl
And a hydrophobic group such as a phenyl group, and R ² is an alkyl group
And n = 1 or 2), a solvent, water and an acid
Mixing SiO ₂ fine particles into a liquid composition consisting of a medium
The sol obtained by stirring the mixture is applied to the substrate
Form a gel film by drying, then bake
This makes it possible to use SiO ₂ as a main component and
It is formed by the gel method, and the uneven layer is integrally formed on the dense layer, and the fine unevenness is formed on the entire surface of the uneven layer to form a roughened photocatalytic coating base film. And

[0013] In ^here, R 1 nSi ^(OR ₂₎ and _4-n,
The mixing ratio of the solvent, water, and acid catalyst was 1: 1 to 1 in molar ratio.
20: 1-20: 0.00001-0.3.

In the above, lower alcohols such as propanol, ethanol and methanol are used alone or as a mixture, or butanol or an alcohol having a higher carbon number than butanol is added thereto in an appropriate amount. Alternatively, organic solvents such as ethers, ketones and amides may be added to these.

The particle size of the SiO ₂ fine particles is preferably 5 nm to ₂ μm.

The fine particles of SiO ₂ are R ¹ nSi (OR ² )
_4-n is hydrolyzed and combined with the product of condensation polymerization, and the surface is covered with a hydrophobic group.

In the above, the liquid composition further contains a trace amount of Si (OR ² ) ₄ or R ³ nSi (OR ² ) _4-n (wherein R ² is an alkyl group and R ³ is hydrophilic at the terminal. a substituent such as _H 2 n _{(CH 2) 3} with a group, n = 1 or 2) may be added to. The addition amount is appropriately changed, but when Si (OR ² ) ₄ is tetraethoxysilane, and when R ¹ nSi (OR ² ) _4-n is methyltriethoxysilane, methyltriethoxysilane of tetraethoxysilane is used. Is a molar ratio x: (1-x) (where 0 <x ≦ 0.3).

Further, in the above method, the S
The amount of the iO ₂ fine particles is preferably 40% by weight or less. If it exceeds 40% by weight, the SiO ₂ fine particles may not be dispersed in the liquid composition.

According to the method for forming a base film for a photocatalytic film of the present invention, the component remaining as a solid, that is, R ¹ nSi (O
R ² ) _4-n is hydrolyzed and condensation-polymerized, and SiO ₂ fine particles whose surface is covered with a product having a hydrophobic group from R ¹ nSi (OR ² ) _4-n and water are dried. Occasionally, a base film for a photocatalytic film having SiO ₂ as a main component and a concavo-convex layer integrally formed on a dense layer is formed in a single step.

According to the method for forming an undercoating film for a photocatalyst film of the present invention, since the sol-gel method is used, low-temperature baking at 200 ° C. or less is possible. Inorganic coatings can be applied to basic substrates with good adhesion to form a base film with excellent processability, and a dense inner layer required as a barrier layer interposed between the photocatalytic film and the substrate, and a photocatalyst It is possible to form a base film having a rough surface layer for applying the film with good adhesion.

Photocatalyst formed by the above method of the present invention
The film base film has a thickness of 0.1 to 10 μm,
preferable. In addition, the surface of the uneven layer of the underlayer for the photocatalytic film is
The surface roughness is 0.03 to 3 μm at the maximum height R _max ,
From concave to nearest concave or convex to nearest convex
Is preferably 0.03 to 10 μm.
Good. On the surface of the uneven layer of the photocatalytic film base film,
In addition to fine irregularities, the equivalent diameter is 0.03-10μ
m, a hole having a depth of 0.03 to 3 μm is formed.
Fine irregularities are also formed on the entire surface and bottom surface
And the surface roughness of the peripheral surface and bottom surface of the hole is the maximum height R
_{The maximum} is 0.01 to 1 μm, and the concave closest to the concave is
The distance from the convex part or the convex part to the nearest convex part is 0.01
Preferably, the thickness is set to １1 μm. Here, equivalent
Diameter is the diameter of a circle having an area equal to the cross-sectional area of the hole
Means Photocatalytic film formed by the method of the present invention
According to the base film for use, SiO ₂ is the main component,
It is formed by the sol-gel method, and has an uneven layer on the dense layer.
Are formed integrally, and fine unevenness is formed on the entire surface of the uneven layer.
Because it is formed and roughened, the action of the dense layer
For example, when the substrate is soda lime glass,
Light sodium photocatalyst coating of TiO ₂ diffuses is
A decrease in the catalytic effect can be prevented. Also,
Even when the base material is plastics,
By being present between the plastic and the photocatalytic film,
Plastics decompose by directly touching titanium dioxide
Can be prevented. The underlayer is uneven on the surface
Since the base film has a smooth surface,
Even photocatalytic coatings such as
It can be applied uniformly. Thus, for example, a barrier
-Even for substrates that do not require an underlayer as a layer,
Suitable for improving the adhesion of the photocatalytic film
Can be used. Next, it is manufactured by the method of the present invention .
The article comprising a substrate having a photocatalyst film formed by using the fabricated photocatalyst film underlayer is formed by coating TiO2 on the surface of the substrate on which the photocatalyst film underlayer is formed.
₂ , a coating agent containing a semiconductor photocatalyst such as ZnO, SrTiO ₃ , CdS, or ZnS that generates a photocatalytic reaction, or a coating agent that forms a semiconductor photocatalyst that generates a photocatalytic reaction by applying heat treatment after application, to form a photocatalytic film. It is characterized by forming. When this product is irradiated with light, a semiconductor such as titanium oxide
Oxidizes harmful substances such as odor components by the photocatalytic effect of photocatalyst
It can be disassembled to purify the air. Another article comprising a substrate having a photocatalytic film formed by using the photocatalytic film base film produced by the method of the present invention is a substrate on which the photocatalytic film base film is formed. A trifunctional compound represented by the formula RSi (X) ₃ (where R is a hydrocarbon group comprising an alkyl group, a phenyl group or a vinyl group, and X is an alkoxyl group or a halogen) on the surface of the base film of the material. A photocatalyst comprising a hydrolyzed / polycondensed product of silane, a tetrafunctional silane represented by the formula Si (X) ₄ (wherein X is an alkoxyl group or a halogen), and titanium dioxide particles as a photocatalyst It is characterized by forming a film. When this article is irradiated with light,
Odor formation due to the photocatalytic effect of a semiconductor photocatalyst such as titanium
It can oxidize and decompose harmful substances such as
Wear. In particular, the photocatalytic film is derived from trifunctional silane.
R (hydrocarbon group) bonded to Si remains in the coating
It has excellent workability to give flexibility, and
The photocatalytic film has an organic base component consisting of R in the film,
Fewer than the inorganic skeleton component consisting of the Si-O-Si component
Therefore, it is excellent in light resistance. And on
The undercoat film and the photocatalyst film mainly include an inorganic component.
For example, the base film and the base film according to the present invention may be
When a photocatalyst film is applied, it is difficult for dirt to adhere
Dirt such as seasonings remaining after washing etc. is also due to the photocatalytic effect.
Can be oxidatively decomposed to maintain beauty over a long period of time
Can be .

[0022]

Next, an embodiment of the present invention will be described.
This will be described with reference to the drawings.

[0023] Figure 1 shows an embodiment of a photocatalytic <br/> medium film for a base film by Ri formed in the method of the present invention. In FIG. 1, an undercoat film (1) for a photocatalytic film has SiO ₂ as a main component and is formed by a sol-gel method.
An uneven layer (3) is integrally formed thereon. Fine unevenness is formed on the entire surface of the uneven layer (3) and the surface is roughened.

The thickness (T) of the photocatalytic underlayer (1) is
0.1 to 10 μm. The surface roughness of the concavo-convex layer (3) is 0.03 to 3 μm in maximum height R _max , and the concavity (4) is closest to the concave part (4) or the convex part (5) is closest to the convex part.
The interval (W) up to (5) is 0.03 to 10 μm.

FIG. 2 shows another embodiment of the base film for a photocatalytic film produced by the method of the present invention. In FIG. 2, the underlayer for photocatalyst film (10) has an equivalent diameter (D) of 0 on the surface of the uneven layer (3) in the underlayer for photocatalyst film (1) similar to FIG. A hole (11) having a thickness of 0.03 to 10 μm and a depth (S) of 0.03 to 3 μm was formed. Fine irregularities are also formed on the entire peripheral surface and bottom surface of the hole (11) and the surface is roughened. The surface roughness of the peripheral surface and bottom surface of the hole (11) is 0.01 _mm at the maximum height R _max . And the distance (W1) from the concave portion (12) to the nearest concave portion (12) or the convex portion (13) to the nearest convex portion (13) is 0.01 to 1 μm.
It has been done.

The method of forming the photocatalytic underlayers (1) and (10) shown in FIGS. 1 and 2 is based on R ¹ nSi (OR ² ).
_4-n (where R ¹ is a hydrophobic group such as an alkyl group and a phenyl group, R ² is an alkyl group, and n = 1 or 2
), A step of applying a sol obtained by stirring a mixture of SiO ₂ fine particles to a liquid composition comprising a solvent, water and an acid catalyst to a substrate, and applying the sol to a substrate. The method includes a step of drying the sol to form a gel film, and a step of baking the gel film. However, if the drying can be performed for a sufficient time, the heat treatment step may be omitted.

Here, R ¹ nSi (O) in the liquid composition
R ² ) _4-n , a solvent, water, and an acid catalyst have a mixing ratio of:
1: 1 to 20: 1 to 20: 0.00001 in molar ratio
It is preferably 0.3, and the amount of the oxide fine particles in the whole raw material is preferably 40% by weight.

The base layer sol can be applied to the substrate by any method such as dip coating, spray coating, bar coating, and roll coating.

The heat treatment of the underlayer is performed at 70 to 500 ° C. for 30 minutes.
This is performed by heating for seconds to 10 minutes. In order to impart chemical and physical durability to the formed barrier layer, it is preferable to perform heat treatment at 100 to 500 ° C.

Another object of the present invention is achieved by applying a photocatalyst coating agent to the above-mentioned underlayer, and comprises a substrate having a photocatalyst layer formed using the underlayer for a photocatalyst layer. Articles can be formed.

The photocatalyst coating agent to be applied on the undercoat film produced by the method of the present invention is prepared by coating TiO ₂ , Z on the surface of the base film on which the undercoat film for photocatalyst film is formed.
Any material that contains a semiconductor photocatalyst such as nO, SrTiO ₃ , CdS, or ZnS that causes a photocatalytic reaction, or that forms a semiconductor photocatalyst that causes a photocatalytic reaction by applying a coating agent and then performing a heat treatment. TiO ₂ , which is inexpensive and has a large photocatalytic effect
TiO ₂ containing anatase-type crystals having high quantum efficiency is particularly preferable.

Examples of the TiO ₂ -based photocatalyst coating agent that can be used in the present invention include titanium alkoxides,
Hydrolysis in the presence of alcohol, water, and acid catalysts,
Examples include those obtained by polycondensation, TiO ₂ particles and a product derived from an alkoxide as a binder for the TiO ₂ particles, or a product containing a fluorine resin or a silicone resin.

The coating agent for the photocatalyst may be applied by any method such as dip coating, spray coating, bar coating, roll coating, and the like. , A base film and a photocatalytic film can be continuously coated.

The film formed by applying the photocatalyst coating agent is heat-treated to crystallize the film when titanium alkoxide is used, and heat-treated as necessary when a binder is used. Is done.

Further, in order to obtain an article comprising a substrate having a photocatalytic film formed by using the photocatalytic film base film produced by the method of the present invention, the above-mentioned photocatalytic film On the surface of the base film on which the base film is formed, the formula RSi
A trifunctional silane represented by (X) ₃ (wherein R is a hydrocarbon group consisting of an alkyl group, a phenyl group or a vinyl group, X is an alkoxyl group or a halogen),
forming a photocatalytic film composed of a hydrolytic / polycondensate with a tetrafunctional silane represented by i (X) ₄ (wherein X is an alkoxyl group or a halogen) and titanium dioxide particles as a photocatalyst. Things.

Here, titanium dioxide is prepared by particles prepared by an industrial method such as a sulfuric acid method or a chlorine method or a hydrothermal method.
A substance prepared by any method such as particles obtained by a sol-gel method is used, and the state of the particles may be either a powder or a state in which the powder is dispersed in a liquid.

In the sulfuric acid method and the chlorine method, titanium dioxide for a pigment having a primary particle diameter of about 0.2 to 0.3 μm and fine particle titanium dioxide having a primary particle diameter of less than 100 nm are obtained depending on the preparation conditions. Particulate titanium dioxide prepared by a chlorine method having small particles and large specific surface area is particularly preferred.

The crystal form of titanium dioxide industrially prepared is rutile type, anatase type, or a mixture of rutile type and anatase type. In the hydrothermal method, brookite type crystals may be precipitated. Here, any crystalline form of titanium dioxide particles can be used, and in some cases, amorphous titanium oxide may be contained, but as the crystalline form, anatase type, or rutile type and anatase type And a mixture containing anatase type having high quantum efficiency in a proportion of 30% by weight or more in the crystal component is more preferable.

Titanium dioxide is added in a suitable amount of not more than 80% by weight in the film according to the required film properties. When the titanium dioxide particle concentration is low, the photocatalytic effect is small and the titanium dioxide particle concentration is low. Since the workability of the film is inferior when it is high, the titanium dioxide concentration is preferably 5 to 80% by weight in the film concentration.

In the above, the trifunctional silane is represented by the formula R
Si (X) ₃ (wherein R is a hydrocarbon group comprising an alkyl group, a phenyl group or a vinyl group, and X is an alkoxyl group or a halogen).

Specifically, methyltriethoxysilane,
Ethyl triethoxy silane, phenyl triethoxy silane, vinyl triethoxy silane, methyl trimethoxy silane, methyl trichloro silane, ethyl trichloro silane, vinyl trichloro silane and the like are used, and at least one kind is used.

The tetrafunctional silane is represented by the formula Si (X) ₄
(Wherein X is an alkoxyl group or a halogen)
It is represented by

Specifically, tetraethoxysilane, tetramethoxysilane, tetrachlorosilane and the like can be mentioned, and at least one kind is used.

Then, after mixing the above-mentioned trifunctional silane and tetrafunctional silane and then subjecting them to hydrolysis and polycondensation as a binder, the above trifunctional silane and tetrafunctional silane are hydrolyzed and polycondensed, respectively. Or a product obtained by mixing and oligomerizing these silane compounds and subjecting them to hydrolysis and polycondensation.

The mixing ratio of trifunctional silane and tetrafunctional silane is
When expressed in a molar ratio of trifunctional silane: tetrafunctional silane = x: (1-x), 0.3 ≦ x <0.7, preferably 0.4 ≦ x
≦ 0.6. When an oligomer of the silane compound is used as a raw material for a binder, the molar ratio corresponds to a monomer conversion value. The reason why the range of x is limited as described above is that if x is too small, R (hydrocarbon group) in the film is reduced, so that the processability of the film is reduced and x
If the particle size is too large, when the surface of the titanium dioxide particles is hydrophilic, the dispersibility of the titanium dioxide particles in the sol containing the binder generated from the silane compound is reduced.

The thickness of the photocatalytic film is 0.05 to 5
μm is preferred.

Next, the method for forming the photocatalytic film comprises the preparation of a sol for forming the photocatalytic film and the formation of the film.

Preparation of Photocatalyst Film-Forming Sol The photocatalyst film-forming sol is prepared by mixing trifunctional silane and tetrafunctional silane with alcohol or other organic solvent, water, and an acid catalyst at a predetermined ratio and stirring. It can be obtained by:

Here, as the acid catalyst, inorganic acids such as sulfuric acid, nitric acid and hydrochloric acid, and organic acids such as acetic acid and oxalic acid are used.

The trifunctional silane and tetrafunctional silane, which are the raw materials of the titanium dioxide binder, may be hydrolyzed and polycondensed, or may be used by mixing oligomers of these silane compounds. May be added at any time before or after the reaction of the silane.

In the above sol raw materials, the ratio of the raw materials other than titanium dioxide is defined as trifunctional silane: tetrafunctional silane: alcohol or other organic solvent: water: acid catalyst = x: (1-
x): When represented by the molar ratio of y: z: a, the values of x, y, z, and a are respectively 0.3 ≦ x <0.7 and 0.5 ≦ y ≦ 100.
0, 0.5 ≦ z ≦ 1000, and 0.00001 ≦ a ≦ 1.

In the above composition, if y is less than 0.5, it is difficult to disperse the particles, and if y exceeds 1,000, the solid component concentration of the prepared sol for forming a photocatalytic film is too low, so that the uniformity is obtained. It is not preferable because it is difficult to form a proper film. On the other hand, if z is less than 0.5, the hydrolysis of the silane takes a long time, and if z exceeds 1000, the sol loses fluidity and may gel, which is not preferable. If a is less than 0.00001, the progress of the hydrolysis reaction of the silane becomes slow, and if a exceeds 1, the reaction proceeds too fast, and the period during which the sol for forming a photocatalytic film can be uniformly applied becomes short. Is not preferred.

The method for producing titanium dioxide used for preparing the sol for forming a photocatalytic film is not particularly limited, but fine particle titanium dioxide prepared by a chlorine method having a small primary particle and a large specific surface area is particularly preferred.

When using titanium dioxide particles dispersed in a liquid, the liquid of the dispersion medium is also included in the above composition.

As the titanium dioxide used for preparing the sol for forming a photocatalytic film, particles of any crystal form can be used, and an amorphous titanium oxide may be contained. Alternatively, a mixture of a rutile type and an anatase type is preferable, and a substance containing an anatase type having a high quantum efficiency of 30% by weight or more in a crystal component is
More preferred.

Titanium dioxide is added in a suitable amount of not more than 80% by weight in the film according to the required film characteristics. When the titanium dioxide particle concentration is low, the photocatalytic effect is small and the titanium dioxide particle concentration is low. Since the workability of the film is inferior when it is high, the titanium dioxide concentration is preferably 5 to 80% by weight in the film concentration.

In the above composition, Si1 in silane was used.
If the average number of R per unit is in the range of 0.3 or more and less than 0.7, a part of the composition of the trifunctional silane is represented by the general formula R ₂ Si (X) ₂ (where R is Is a hydrocarbon group consisting of an alkyl group, a phenyl group or a vinyl group, and X is an alkoxyl group or a halogen).

Film Formation The sol for forming a photocatalytic film is applied to a base material such as a metal plate, a panel, a tile, and a plastics via the base film (barrier layer) according to the present invention. The application method is
Any method such as dip coating, spray coating, bar coating, and roll coating can be used.

The photocatalyst film can be obtained by drying the substrate coated with the sol for forming a photocatalyst film at a temperature of room temperature or higher. When forming a film in a short time,
In addition to drying, heat treatment may be performed at 500 ° C. or less.
When heat treatment is performed at 0 to 500 ° C. for a long time, R (hydrocarbon group) bonded to Si atoms is calcined and desorbed, and the flexibility of the film is reduced. Therefore, to maintain workability, heat treatment at 300 ° C. or less is preferable. .

The thickness of the photocatalytic film is not particularly limited, but if the film thickness is less than 0.05 μm, it is difficult to form a defect-free film, and if the film thickness is more than necessary, the photocatalytic effect corresponding to the thickness is insufficient. Since there is no improvement and it is uneconomical, the film thickness is preferably 0.05 to 5 μm. However,
In the case where titanium dioxide is used also for the function of shielding ultraviolet rays, a film thickness of 5 μm or more may be used.

The photocatalytic film has excellent workability because R bonded to Si derived from trifunctional silane.
This is because (hydrocarbon groups) remain in the film to give flexibility. Further, the photocatalytic film is excellent in light resistance because the organic group component consisting of R in the film is Si-O-Si.
Components, and even if the organic group component in the binder is oxidatively decomposed by the photocatalytic effect of titanium dioxide, most of the binder in the film is not decomposed by the photocatalytic effect of titanium dioxide.
This is because it is made of an i-O-Si component and no chalking occurs.

It is to be noted that since the undercoat film is formed of an oxide film containing silicon dioxide as a main component and is an inorganic-organic composite having irregularities on the surface, the adhesion of the photocatalytic film is improved by the irregularities on the surface. It can be suitably used as a base film (barrier layer) of a photocatalytic film because it is excellent in workability and light resistance, and is most suitable when workability is required.

[0063]

EXAMPLES Hereinafter, specific examples of the present invention will be described together with comparative examples.

Example 1 Methyltriethoxysilane, ethanol and 2-propanol as solvents, water, hydrochloric acid, and SiO 2 having a particle size of 0.01 to 0.02 μm dispersed in 2-propanol
_Two particles were prepared as raw materials. In addition, ₂ -propanol in which SiO ₂ particles were dispersed was used as a part of the solvent. Methyltriethoxysilane, solvent (ethanol, 2
The raw materials are mixed so that the molar ratio of propanol is 1: 1), the molar ratio of water and hydrochloric acid is 1: 5: 4: 0.005, and the particle concentration is 10% by weight, to hydrolyze methyltriethoxysilane. A sol was obtained by condensation polymerization. Then, an aluminum substrate, a panel surface material coated with a film mainly composed of polyester on the aluminum surface, and a soda lime glass substrate were immersed in the sol,
After lifting at a lifting speed of 2 mm / sec and drying,
The resultant was baked at 200 ° C. for 5 minutes to form a base film for a photocatalyst film on the surface of the base material.

Observation of the underlayer for photocatalytic film formed on the surface of the aluminum substrate by SEM showed that the film thickness was 0.8 μm, and fine unevenness was formed on the entire surface of the dense layer to roughen the surface. The formed uneven layer was integrally formed. The surface roughness of the uneven layer is 0.03 at the maximum height R _max .
And the distance from the concave portion to the nearest concave portion or the convex portion to the nearest convex portion is 0.03 to 0.1 μm.
m. Furthermore, on the surface of the uneven layer, in addition to minute unevenness, an equivalent diameter of 0.05 to 0.1 μm and a depth of 0.05 to
Holes of 0.1 μm were formed in an amount of 5 × 10 ⁹ / cm ² or more. Fine irregularities are also formed on the entire peripheral surface and bottom surface of the hole, and the surface is roughened. The surface roughness of the peripheral surface and bottom surface of the hole is 0.03 to 0.05 μm at the maximum height R _max . In addition, the distance from the concave portion to the nearest concave portion or from the convex portion to the nearest convex portion was 0.03 to 0.05 μm.

Example 2 After immersing an aluminum substrate, a panel surface material obtained by applying a film containing polyester as a main component on an aluminum surface, and a soda lime glass substrate in a sol,
When pulling up the substrate, the pulling speed is 20 mm /
A base film for a photocatalytic film was formed on the surface of the base material in the same manner as in Example 1 except that the time was changed to seconds.

Observation of the underlying film for a photocatalytic film formed on the surface of the aluminum substrate by SEM revealed that the film thickness was 2.6 μm, and fine irregularities were formed on the entire surface of the dense layer to roughen the surface. The formed uneven layer was integrally formed. The surface roughness of the uneven layer is 0.03 at the maximum height R _max .
And the distance from the concave portion to the nearest concave portion or the convex portion to the nearest convex portion is 0.03 to 0.1 μm.
m. Furthermore, in addition to fine irregularities, an equivalent diameter of 0.2 to 0.5 μm and a depth of 0.2 to 0.5
3.8 × 10 ⁷ holes / cm ² , equivalent diameter 0.0
5 × 0.1 μm, 0.05 × 0.1 μm deep holes 5 ×
More than 10 ⁹ pieces / cm ² were formed. Fine irregularities are also formed on the entire peripheral surface and bottom surface of these holes to roughen them, and the surface roughness of the peripheral surface and bottom surface of the holes is 0.03 to 0.1 μm at the maximum height R _max . The distance from the concave portion to the nearest concave portion or the convex portion to the nearest convex portion is:
It was 0.03-0.1 μm.

Example 3 An aluminum substrate and a panel in which a film mainly composed of polyester was applied to the aluminum surface in the same manner as in Example 1 except that 2-propanol was used alone as the solvent in the liquid composition. A base film for a photocatalytic film was formed on the surface material and the surface of the soda lime glass substrate.

Observation of the underlying film for a photocatalytic film formed on the surface of the aluminum substrate by SEM revealed that the film thickness was 0.6 μm, and fine unevenness was formed on the entire surface of the dense layer to roughen the surface. The formed uneven layer was integrally formed. The surface roughness of the uneven layer is 0.03 at the maximum height R _max .
And the distance from the concave portion to the nearest concave portion or the convex portion to the nearest convex portion is 0.03 to 0.1 μm.
m. Furthermore, on the surface of the uneven layer, in addition to minute unevenness, an equivalent diameter of 0.05 to 0.1 μm and a depth of 0.05 to
At least 5 × 10 ⁹ holes / cm ^{2 of} 0.1 μm are formed, and fine irregularities are also formed on the entire peripheral surface and bottom surface of the hole to roughen the surface. Has a maximum height R _max of 0.03 to 0.05 μm, and an interval from a concave portion to a nearest concave portion or a convex portion to a nearest convex portion is 0.03 to 0.05 μm. there were.

Example 4 After immersing an aluminum substrate, a panel surface material having a coating mainly composed of polyester on an aluminum surface in a sol, and a soda lime glass substrate in a sol,
A base film for a photocatalyst film was formed on the surface of the base material in the same manner as in Example 3 except that the pulling speed at the time of raising the base material was set to 5 mm / sec.

Observation of the underlayer for the photocatalytic film formed on the surface of the aluminum substrate by SEM showed that the film thickness was 1.3 μm, and fine irregularities were formed on the entire surface of the dense layer to roughen the surface. The formed uneven layer was integrally formed. The surface roughness of the uneven layer is 0.03 at the maximum height R _max .
And the distance from the concave portion to the nearest concave portion or the convex portion to the nearest convex portion is 0.03 to 0.1 μm.
m. Further, in addition to fine irregularities, an equivalent diameter of 0.1 to 0.2 μm and a depth of 0.1 to 0.2
μm of pores 1.8 × 10 ⁸ pieces / cm ^2, equivalent diameter 0.0
5 × 0.1 μm, 0.05 × 0.1 μm deep holes 5 ×
More than 10 ⁹ pieces / cm ² were formed. Fine irregularities are also formed on the entire peripheral surface and bottom surface of these holes to roughen them, and the surface roughness of the peripheral surface and bottom surface of the holes is the maximum height R
_max is 0.03 to 0.07 μm, and the interval from the concave portion to the nearest concave portion or the convex portion to the nearest convex portion is:
It was 0.03-0.07 μm.

Example 5 After immersing an aluminum substrate, a panel surface material having a coating mainly composed of polyester on an aluminum surface, and a soda lime glass substrate in a sol,
When pulling up the substrate, the pulling speed is 20 mm /
A base film for a photocatalytic film was formed on the surface of the base material in the same manner as in Example 3 except that the time was changed to seconds.

Observation of the underlayer for the photocatalytic film formed on the surface of the aluminum substrate by SEM showed that the film thickness was 2.8 μm, and fine irregularities were formed on the entire surface of the dense layer to roughen the surface. The formed uneven layer was integrally formed. The surface roughness of the uneven layer is 0.03 at the maximum height R _max .
And the distance from the concave portion to the nearest concave portion or the convex portion to the nearest convex portion is 0.03 to 0.1 μm.
m. Furthermore, in addition to fine irregularities, an equivalent diameter of 0.2 to 0.5 μm and a depth of 0.2 to 0.5
1.1 × 10 ⁸ holes / cm ^{2 with} an equivalent diameter of 0.0 μm
5 × 0.1 μm, 0.05 × 0.1 μm deep holes 5 ×
More than 10 ⁹ pieces / cm ² were formed. Fine irregularities are also formed on the entire peripheral surface and bottom surface of these holes to roughen them, and the surface roughness of the peripheral surface and bottom surface of the holes is the maximum height R
_max is 0.03 to 0.1 μm, and the interval from the concave portion to the nearest concave portion or the convex portion to the nearest convex portion is:
It was 0.03-0.1 μm.

Example 6 In the same manner as in Example 1 except that a mixture of 1-butanol and 2-propanol in a molar ratio of 48:52 was used as a solvent in the liquid composition. An aluminum substrate, a panel surface material in which a film containing polyester as a main component was applied to the aluminum surface, and a base film for a photocatalytic film were formed on the surface of a soda lime glass substrate.

When the underlayer for the metal photocatalyst film formed on the surface of the aluminum substrate was observed by SEM, the film thickness was 0.8 μm, and fine irregularities were formed on the entire surface of the dense layer, and the rough surface was formed. The formed uneven layer was integrally formed. The surface roughness of the concavo-convex layer is set to a maximum height R _max of 0.
The distance from the concave portion to the nearest concave portion or the convex to the nearest convex portion is 0.03 to 0.1 μm.
It was 1 μm.

Example 7 An aluminum substrate, a panel surface material coated with a film containing polyester as a main component on an aluminum surface, and a soda lime glass substrate were immersed in a sol.
When pulling up the substrate, the pulling speed is 20 mm /
A base film for a photocatalyst film was formed on the surface of the base material in the same manner as in Example 6 except that the time was changed to seconds.

Observation of the underlayer for the metal photocatalyst film formed on the surface of the aluminum substrate by SEM showed that the film thickness was 2.4 μm, and fine unevenness was formed on the entire surface on the dense layer, and the rough surface was formed. The formed uneven layer was integrally formed. The surface roughness of the concavo-convex layer is set to a maximum height R _max of 0.
The distance from the concave portion to the nearest concave portion or the convex to the nearest convex portion is 0.03 to 0.1 μm.
It was 1 μm.

COMPARATIVE EXAMPLE Methyltriethoxysilane, 2-propanol, water and hydrochloric acid, and the amounts of the respective components were in a molar ratio of 1:
A liquid composition of 5: 4: 0.005 was prepared. The liquid composition was mixed, and a sol was obtained by hydrolysis and condensation polymerization of methyltriethoxysilane. Next, an aluminum substrate in this sol, a panel surface material in which a film containing polyester as a main component was applied to the aluminum surface,
The soda lime glass substrate was immersed, pulled up at a pulling rate of 5 mm / sec, dried, and baked at 200 ° C. for 5 minutes to form an undercoat film for a photocatalyst film on the surfaces of the substrates.

Observation of the base film for photocatalytic film formed on the surface of the aluminum substrate revealed that the film thickness was 0.8 μm. Further, the entire film was dense and the surface was entirely smooth.

Evaluation Test In the above Examples and Comparative Examples, a flex resistance test, an adhesion test of the photocatalytic film to the undercoat film, and a deodorizing test of the photocatalytic film applied to the undercoat film were performed on the undercoat film applied.

In the bending resistance test, an aluminum substrate and a panel surface material obtained by applying a film containing polyester as a main component on an aluminum surface were used as the base material on which the base film was applied. In the adhesion test, an aluminum substrate, a panel surface material obtained by applying a film containing polyester as a main component on the aluminum surface, and a soda lime glass substrate were used. Further, in the deodorizing test, a sample in which a photocatalytic film was applied to the surface of a soda lime glass substrate via a photocatalytic film base film was performed.

The bending resistance (workability) test was conducted according to JIS K5
400 using a 2 mm diameter mandrel according to the method of 400.
° Check if there is no cracking or peeling by bending and visual inspection,
evaluated. The results of the obtained bending resistance test are summarized in Table 1 below.

The adhesion test of the photocatalyst film to the undercoat film was performed by the following method.

As a raw material of the sol for forming a photocatalytic film, anatase type titanium dioxide particles (trade name: ST-21, manufactured by Ishihara Sangyo Co., Ltd.), tetraethoxysilane, 2-propanol, water and hydrochloric acid were prepared. These ratios are as follows: tetraethoxysilane: 2-propanol: water: hydrochloric acid = 1: 5:
4: 0.005 (molar ratio) and the concentration of TiO ₂ is 10
It mixed so that it might become weight% and stirred, and prepared the sol for photocatalyst film formation.

Next, this sol was coated with three types of base materials, ie, an aluminum substrate and a panel having a polyester-based film as a main component on the aluminum surface, on which a photocatalytic film base film was formed in Examples 1 to 7 and Comparative Example. Immerse the surface material and soda lime glass substrate, 20m
The film was pulled up at a pulling speed of m / sec and dried at room temperature for 5 minutes to form a photocatalytic film, which was evaluated by the presence or absence of film peeling during drying. Table 1 below summarizes the results of the adhesion test of the photocatalytic film to the obtained base film.

In the above, among the samples in which the photocatalytic film was not peeled off, those coated on a soda lime glass substrate were further heat-treated at 200 ° C. for 5 minutes to obtain a sample for a deodorizing test.

In the deodorizing test for confirming the deodorizing power, a substrate (effective area: 200 cm ² ) coated with a photocatalytic film was fixed in a polyvinyl fluoride bag, and the bag was sealed by heat sealing. 3 liters of air containing 500 ppm of ammonia is sealed, light is irradiated from above by a 20 W black light, and 24 hours after the start of the light irradiation, the gas concentration in the bag is measured by a gas detector tube, and the method is performed for 24 hours. The subsequent ammonia removal rate% was measured.

The distance between the substrate and the black light is 30.
cm, and the gas concentration after light irradiation was measured in the same manner without inserting the substrate coated with the photocatalytic film, and this was used as a blank test. The results of the deodorizing test of the formed film are shown in Table 1 below.

[0089]

[Table 1] As is clear from Table 1 above, in Examples 1 to 7, it is found that a base film having excellent bending resistance (workability) and capable of applying a photocatalytic film as an upper coating film can be formed. Further, the photocatalyst films obtained in Examples 1 to 7 show an excellent deodorizing effect. On the other hand, in the comparative example, the bending resistance (workability) was excellent, but the adhesion of the photocatalytic film was poor.

In the deodorizing test, in the blank test, the removal rate of ammonia was 34%. This is considered to be because ammonia was adsorbed on the bag used for the test.

Example 8 Examples 1 to 7 in which a base film for a photocatalytic film was formed
A photocatalytic film was formed on the surface of the base film of the substrate using the following sol for forming a photocatalytic film.

That is, fine titanium dioxide particles having an average primary particle diameter of 28 nm (anatase type: 84%, rutile type: 16%) prepared by a chlorine method as titanium dioxide, and other raw materials such as methyltriethoxysilane, tetraethoxysilane and 2-propanol , Water and hydrochloric acid were prepared. These ratios are as follows: methyltriethoxysilane: tetraethoxysilane: 2-propanol: water: hydrochloric acid = 0.5: 0.
The mixture was mixed at a molar ratio of 5: 5: 4: 0.005 so as to have a titanium dioxide concentration of 10% by weight, and stirred to prepare a sol for forming a photocatalytic film.

Next, the base material on which the base films of Examples 1 to 7 were formed was immersed in the sol, pulled up at a pulling rate of 2 mm / sec, dried for 5 minutes at room temperature, and then dried for 200 minutes for 5 minutes. It heat-processed at ° C, and formed a photocatalyst film. When the adhesion was evaluated based on the presence or absence of film peeling during drying of the obtained photocatalyst film, the adhesion of the photocatalyst film to the base film was sufficiently excellent in each case.

[0094]

According to the present invention , formation of a base film for a photocatalytic film is provided.
The method is as described above for R ¹ nSi (OR ² )
_4-n (where R ¹ is a hydrophobic group such as an alkyl group and a phenyl group, R ² is an alkyl group, and n = 1 or 2
), A solution obtained by mixing a mixture of a solvent, water, and an acid catalyst with fine particles of SiO ₂ is applied to a substrate, followed by drying, and drying the gel film. Is formed and then fired to obtain SiO ₂
As the main component, and the uneven layer is integrally formed on the dense layer.
And fine irregularities are formed on the entire surface of the irregular
Characterized in forming a photocatalyst film for a base film which is roughened, according to the method for forming a photocatalytic film for a base film of the present invention, component remaining as solid, i.e. R ¹ nSi
(OR ² ) _4-n is hydrolyzed and condensed and polymerized, and SiO ₂ fine particles whose surface is covered with a product having a hydrophobic group from R ¹ nSi (OR ² ) _4-n and water are a film. By being repelled at the time of drying, a base film for a photocatalytic film having SiO ₂ as a main component and an uneven layer integrally formed on a dense layer is formed in one step. According to the method for forming a base film for a photocatalytic film of the present invention, since the sol-gel method is used, low-temperature sintering is possible, and an inorganic film can be applied to various base materials with good adhesion, and has excellent workability. And a dense inner layer required as a barrier layer interposed between the photocatalytic film and the substrate,
This has the effect of forming a base film having a rough surface layer for applying the photocatalytic film with good adhesion at the same time.

Further, the photocatalyst produced by the method of the present invention can be used.
The base film for the medium film contains SiO ₂ as a main component,
It is formed by the sol-gel method, and has an uneven layer on the dense layer.
Are formed integrally, and fine unevenness is formed on the entire surface of the uneven layer.
It is formed and roughened, and has an uneven layer on the surface
Therefore, if the surface of the underlying film is smooth,
Even with a medium film, uniformity due to the mechanical adhesion of the uneven layer
Can be applied. Therefore, for example, as a barrier layer
It is a top coat even for substrates that do not require a base film
Appropriately used to improve the adhesion of the photocatalytic film
be able to. And, according to the undercoat film for the photocatalytic film,
For example, due to the action of the dense layer,
In the case of lath, sodium
To prevent the photocatalytic effect of TiO ₂ from deteriorating due to
Can be stopped. The base material is plastics
In this case, the undercoat film is made of plastics and a photocatalytic film.
Plastics directly
It can be prevented from being decomposed by touching titanium.

[Brief description of the drawings]

1 is an enlarged perspective view-out partially cutaway showing an embodiment of by Ri manufactured photocatalyst film for a base film in the method of the present invention.

2 is an enlarged perspective view-out partially cutaway showing another embodiment of by Ri manufactured photocatalyst film for a base film in the method of the present invention.

[Explanation of symbols]

 1,10 Base film for photocatalytic film 2 Dense layer 3 Uneven layer

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C09D 183/04

Claims (6)

(57) [Claims] 1. The method according to claim 1, wherein R ¹ nSi (OR ² ) _4-n (wherein
R ¹ is an alkyl group, a hydrophobic group such as a phenyl group, R ²
Is an alkyl group, n = 1 or 2) and a solvent
, Water, and an acid catalyst, SiO ₂ fine particles
The sol obtained by stirring the mixture of
Form a gel film by applying it to the substrate and drying it,
Then, by baking, a light having SiO ₂ as a main component, an uneven layer formed integrally on the dense layer, and fine unevenness formed on the entire surface of the uneven layer to roughen the surface.
And forming a catalyst coating for the base film, method for forming a photocatalytic film for the base film. 2. R ¹ nSi (OR ² ) _4-n and a solvent
, Water, and the acid catalyst are mixed at a molar ratio of 1: 1 to 2
0: 20: .00001 to 0.3, method for forming a photocatalytic film for a base film of claim 1, wherein. 3. The amount of fine particles of SiO ₂ in the whole raw material is 40.
Ru der% by weight or less, according to claim 1 or 2 method for forming a photocatalytic film for a base film according. 4. A film thickness of the formed photocatalyst film for a base film is 0.1 to 10 [mu] m, method for forming a photocatalytic film for a base film of claim 1, wherein. 5. The surface roughness of the concavo-convex layer of the formed base film for a photocatalytic film is 0.03 to 3 μm in maximum height R _max , and the concavity closest to the concave part or the convex part closest to the convex part. distance to have been made with 0.03～10Myuemu, method for forming a photocatalytic film for a base film of claim 1 Symbol placement. 6. The surface of the uneven layer of the formed photocatalytic film underlayer has not only fine unevenness but also an equivalent diameter of 0.03.
10 to 10 μm, having a depth of 0.03 to 3 μm,
Fine irregularities are also formed on the entire peripheral surface and the bottom surface of the hole to roughen the surface. The surface roughness of the peripheral surface and the bottom surface of the hole is 0.01 to 1 μm at the maximum height R _max , and the concave portion from the interval of the concave portion or the convex portion closest to the protrusions closest have been made with 0.01 to 1 [mu] m, method for forming a photocatalytic film for a base film of claim 1 Symbol placement.