JP2003027000A - Photocatalytic film and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent photocatalytic film which exhibits a photocatalytic action even under the conditions of no ultraviolet rays or a weak intensity of ultraviolet rays and, simultaneously, harmonizes a photocatalytic activity such as stainproofness with water repellency and abrasion resistance. SOLUTION: The photocatalytic film formed on the surface of a substrate is composed of at least TiO2 crystalline fine particles as the photocatalyst and SiO2 as the film-forming component and obtained by forming a film from a coating fluid comprising, as the raw material of the SiO2 source, a trialkoxysilane of the formula: R1-Si(OR2)3 (wherein R1 and R2 are each a >=1C alkyl group), and then subjecting the film to the heat treatment at 100 deg.C-650 deg.C to obtain a photocatalytic film having an irregularity in the film surface and voids inside the film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-repellent photocatalytic film exhibiting organic substance decomposing property, antibacterial property, deodorizing property, antifouling function and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Recently, titanium oxide has a photocatalytic effect.
Various products with degradability, antibacterial, deodorant and antifouling functions
It has been developed and many patents have been filed. Among them, photocatalyst
Semiconductor crystal fine particles (for example, TiO 2₂Crystal particles)
SiO, which is a hydrophilic substance as an inder₂Combine
The coating system has a photocatalytic activity even when heat-treated at room temperature or low temperature.
It has the advantage that the property is exhibited. In addition, as a raw material,
TiO like₂Ti (OC)₃H
₇)_FourHydrolyzate such as SiO and₂600 in combination
TiO in the film by heat treatment at about ℃₂Crystal
From the beginning, the coating system to be deposited is photocatalytic semiconductor crystal fine particles.
Has the advantage of higher durability than coating systems that use
It

[0003]

However, in the case of using TiO ₂ crystal fine particles as a raw material, if an attempt is made to increase the catalytic activity of the photocatalyst film, anatase-type titanium oxide fine particles are used, and the content thereof is increased. It becomes possible to enhance the catalytic activity of the photocatalytic film. However, if a large amount of TiO ₂ crystal fine particles is used, the hardness of the formed film is lowered and the wear resistance is deteriorated. Further, TiO ₂ without using the TiO ₂ crystal fine particles as a raw material
The method of depositing crystals in the film has a problem that, in the case of low temperature treatment, TiO ₂ does not become anatase crystals and the performance of the photocatalyst is not exhibited.

[0004]

The present invention has been made in view of the above-mentioned problems, and by using trialkoxysilane as a raw material of a SiO ₂ source, unevenness of the film surface and voids inside the film ( The present invention provides an excellent photocatalyst film that can be made porous and has both photocatalytic activity such as antifouling property, water repellency, and abrasion resistance, and a method for producing the same.

That is, in the photocatalyst film of the present invention, in the photocatalyst film formed on the surface of the substrate, at least TiO ₂ crystal fine particles as a photocatalyst and SiO ₂ as a film forming component are used.
Consists, trialkoxysilane as a raw material for the SiO ₂ source _{(R1-Si (OR2) 3} ) ( where, R1, R2: indicates the number 1 or more alkyl groups carbons) water-repellent, which is formed by the coating solution consisting of It is characterized by having.

The photocatalyst film of the present invention is characterized in that the content of TiO ₂ crystal fine particles is 10 to 70% by weight and the content of SiO ₂ is 30 to 90% by weight.

Further, in the photocatalyst film of the present invention, the content of TiO ₂ crystal fine particles is 25 to 45% by weight, the content of SiO ₂ is 30 to 50% by weight, and the content of ZrO ₂ is 25 to 60%.
It is characterized in that it is wt%.

Furthermore, the photocatalyst film of the present invention is characterized by having irregularities on the film surface and voids inside the film.

Further, the photocatalyst film of the present invention is characterized by being used for automobile glass.

Further, in the method for producing a photocatalyst film of the present invention, TiO ₂ crystal fine particles and trialkoxysilane (R 1 -Si (OR 2) ₃ ) as a raw material of a SiO ₂ source (provided that R 1, R 2 : Shows an alkyl group having 1 or more carbon atoms) to form a film, and then 100 ° C. to 650 ° C.
The water-repellent photocatalytic film having unevenness on the film surface and voids inside the film is formed by performing the heat treatment of.

Furthermore, the method for producing a photocatalyst film of the present invention comprises:
It is characterized in that the substrate with the photocatalyst film is bent and / or strengthened into a predetermined shape by heat-treating at a temperature of 560 to 650 ° C. after forming the film.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the photocatalyst film of the present invention, the photocatalyst film formed on the surface of the substrate is at least Ti as a photocatalyst.
It is composed of O ₂ crystal fine particles and SiO ₂ as a film-forming component, and trialkoxysilane (R 1 -Si (OR 2) ₃ ) as a raw material of the SiO ₂ source (where R 1 and R 2: carbon number 1
It is characterized in that it has water repellency and is formed into a film by a coating liquid containing the above alkyl group).

The trialkoxysilane (R1-Si (O
R2) ₃ ) (however, R1 and R2: an alkyl group having 1 or more carbon atoms) preferably has 1 to 4 carbon atoms in terms of compatibility with the coating solution and hardness of the produced film. Further, 1-2 are more preferable, and for example, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane and the like can be used. This is because if the carbon numbers of R1 and R2 are too large, it becomes difficult to dissolve in the coating solution and the hardness of the produced film decreases.

The content of SiO ₂ formed from the above-mentioned trialkoxysilane raw material is preferably 30 to 90% in terms of oxide weight% in the photocatalyst film, and more preferably 30 to 70%. . The content of SiO ₂ formed from the raw material of trialkoxysilane is 30%
If it is less than 9, the water repellency is poor and the contact angle is low.
When it is 0% or more, the content of the TiO ₂ crystal fine particles which is a photocatalytic semiconductor is reduced, and the photocatalytic activity is not exhibited, which is not preferable.

Since the trialkoxysilane is trifunctional, the number of hands that can be bonded is three, and the remaining one is free. Therefore, it has a sparser structure than the tetrafunctional silica and becomes porous. As a result, it is considered that the specific surface area can be increased in a state where durability such as abrasion resistance is hardly reduced as compared with the case of using tetrafunctional, and that it also has an effect of enhancing the photocatalytic ability of the coating.

Further, the photocatalyst film of the present invention exhibits good water repellency due to the alkoxy group attached to Si, and 650
Even if it is baked at ℃, the alkyl group does not burn and remains excellent in water repellency.

Further, TiO₂As the source material, TiO₂
Use fine crystal particles. TiO used ₂Crystal particles are special
Powdered TiO for photocatalyst₂Fine particles
It is also possible to use a child or a drug solution, and to use a powdery optical touch.
Medium TiO₂As the fine particles, for example, ST-01, S
T-21 (manufactured by Ishihara Techno Co., Ltd.), SSP-25, SS
P-20 (manufactured by Sakai Chemical Industry Co., Ltd.), PC-101 (Chita)
Industrial Co., Ltd.), Super Titania F-6, Super
-Titania F-5 (Showa Titanium Co., Ltd.), D
Use N-22A (manufactured by Furukawa Machinery Co., Ltd.)
Is possible. Further, as the photocatalyst chemical liquid, for example,
STS-01, STS-02 (manufactured by Ishihara Techno Co., Ltd.),
Use of A-6, M-6 (manufactured by Taki Chemical Co., Ltd.), etc.
Is also possible, and further, TiO for photocatalyst₂Fine particles and siri
ST-K01, ST-K03 which is a mixture with mosquito raw material
(Ishihara Techno Co., Ltd.) and the like can also be used. Na
Powdered TiO for photocatalyst₂Fine particles turn powder into liquid
Mixing operations commonly used to disperse, such as
It can be easily dispersed in a film chemical with
In the case of SiO₂There is no problem even if mixed and dispersed with the source. Na
Oh, TiO in the film₂TiO for photocatalyst used as a source₂Conclusion
Fine particles or TiO in chemical liquid₂The average particle size of the fine particles is
If the thickness is 30 nm or less, the transparency and durability of the film
It is preferable from the viewpoint of enhancing the property.

As a component of the photocatalyst film, TiO₂,
SiO₂Alkali resistance and photocatalytic ability
ZrO to improve₂Contains 25-60% by weight of ingredients
Is preferable, and if it exceeds 60% by weight, abrasion resistance and /
Or the photocatalytic ability becomes poor. Also, TiO₂, Si
O₂, ZrO₂As a component other than, for example, Al₂O₃, B
₂O ₃, SnO₂Such as oxides, C (carbon), etc.
It may be contained.

The method for forming the photocatalyst film is not particularly limited, but a general method such as a dip coating method, a spin coating method, a roll coating method, a bar coating method, a spray coating method or a screen printing method is used. The film can be formed by a film method.

After the photocatalyst film is formed, 100 ° C. to 650 ° C.
Heat treatment is performed at the temperature of. The heat treatment can be performed in two steps. The upper limit of the heat treatment time is not particularly limited, and heat treatment for 24 hours is not a problem, but the upper limit of the heat treatment time is preferably about 2 hours for maintaining the final heat treatment temperature in view of productivity. .

The thickness of the photocatalyst film is 30 nm to 500 n.
If m, the formed film has photocatalytic activity,
More preferably, the film thickness of 50 nm to 300 nm is more preferable because a photocatalytic film having good translucency can be obtained by one film formation.

The photocatalyst film of the present invention is used for a building window material, a vehicle window material, an exterior tile, for the purpose of improving visibility and preventing stains.
It has sufficient durability and antifouling property due to photocatalyst even in the usage environment that requires durability such as using a photocatalyst film on the outdoor side such as exterior panels, and also shows antifouling property due to the water repellency of the alkyl group. . In addition, since it has high durability even when it is used outside the room, its purpose is to impart an antifouling function, a visibility improving function by water repellency, etc., for example,
Architectural, automotive or airplane window materials, store showcases and industrial window materials, vehicle mirrors such as door mirrors and bathroom mirrors, ceramics such as exterior tiles, aluminum and SUS, etc. As long as it is a material that does not deteriorate by heat treatment such as metal or organic material, it can be used by forming a film on any base material. In particular, it has an excellent antifouling function, so it is used for exteriors for construction and automobiles. Suitable for window materials. In particular, in the case of glass for automobiles, heat treatment is performed at a temperature of 560 to 650 ° C. for bending and / or tempering. However, since the photocatalyst film is porous, glass is heat-treated even at such a high temperature. It has the advantage that the alkaline component, which is the component inside, can be prevented from migrating to the photocatalyst film, and the photocatalytic activity hardly deteriorates.

When the base material is glass, clear or other colored glass such as blue, gray, bronze and green, glass such as meshed glass, bending, semi-strengthening and strengthening , Ordinary double glazing or Lo
Multi-layer glass with glass coated with a metal film such as w-E film, multi-layer glass with gel or the like between the glass, laminated glass, drilling, vapor deposition or sputtering on the side opposite to the photocatalyst film, Various processes such as applying a film such as a metal film or an oxide film resin film with a coat such as a print, and processing the surface opposite to the photocatalyst film by etching or sandblasting, or a combination thereof may be performed.

[0024]

The TiO ₂ crystal fine particles in the photocatalyst film of the present invention are
When it is irradiated with ultraviolet rays contained in sunlight or fluorescent lamps, it exhibits an action of decomposing organic substances adhering to the coating surface by a photocatalytic effect and keeping the surface of the coating clean (called oxidative decomposition type reaction).

Therefore, in the present invention, since Si exhibits a photocatalytic action even in a situation where there is no ultraviolet light or the intensity of ultraviolet light is weak, Si is used.
By containing trialkoxysilane as a raw material of the SiO ₂ source while containing O ₂ as well, the photocatalyst film formed has very fine irregularities on the film surface and the inside of the film is very porous (high porosity). This makes it possible to significantly enhance the photocatalytic ability (catalytic activity) of the coating film, and also has the effect of enhancing durability such as water repellency and abrasion resistance.

By having the above-mentioned coating structure,
The coating has a photocatalytic ability and high durability, especially abrasion resistance, and even when dirt such as exhaust gas or dust is temporarily attached to the surface of the coating, organic components are decomposed by the photocatalytic effect.

[0027]

EXAMPLES The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples. The quality of the obtained photocatalytic film was evaluated by the method described below.

Abrasion resistance Based on the abrasion resistance test method described in JIS R 3221, a haze value was evaluated by performing a Taber type abrasion test with an abrasion wheel CS-10F and a load of 500 gf. Evaluation,
The initial haze value H ₀ and the haze value H ₁₀₀ after 100 times,
The haze value H ₂₀₀ after 200 times is H ₀ ≦ H ₁₀₀ ≦ H ₂₀₀ , and the haze change amount ΔH (ΔH = H ₂₀₀ −
When H ₀ ) is ΔH ≦ 4%, it is regarded as a pass (◯), and H ₁₀₀
Those with> H ₂₀₀ or ΔH> 4% were regarded as rejects (x).

The photocatalytic activity of the ability to decompose the stains on the photocatalytically active surface was evaluated by the degree of decomposition of stearic acid. The evaluation method is Parago
n 1000 (Perkin-Elmer Co.,
Ltd. Manufactured by FT-IR spectrometer), 2910c
C of stearic acid appearing from m-1 to 2920 cm-1
The peak intensity (absorbance A) resulting from the -H stretching vibration was determined for each of Ab before stearic acid application, A0 during stearic acid application, and A1 after irradiation with ultraviolet rays for 1 hour.
Amount of change in peak intensity: {(A0-Ab)-(A1-A
b)} × 1000 was calculated as the decomposition degree of stearic acid. (The higher the degree of stearic acid decomposition, the higher the photocatalytic activity.) Note that the application of stearic acid to the sample was 3
The sample was immersed in a wt% stearic acid-ethanol solution and pulled up at 8 mm / sec. Black light FL15BLB (Toshiba Electric Co., Ltd.)
Product), and the ultraviolet intensity of the sample surface is 4 mW / c
m ² (365 nm).

Surface observation of the film surface (a) Scanning electron microscope (SEM) [Hitachi S
-4500, accelerating voltage 5.0 kV, magnification 50,000 times]. (B) Cyclic contact mode of scanning probe microscope Atomic force microscope (CC-AFM) [Seiko Denshi Kogyo KK, SPI3700, 2.5 μm square scan] was used for observation. The center line average roughness of the obtained photocatalytic film is shown by the surface-expanded average surface roughness Ra value (nm).

Film thickness and refractive index automatic ellipsometer [DVA-F manufactured by Mizojiri Optical Co., Ltd.
L3G].

Example 1 [Sample preparation] The coating liquid for forming a coating was methyltriethoxysilane (MTES, manufactured by Kishida Chemical Co., Ltd.) as a SiO ₂ raw material, and PC-201 (Titanium Industry Co., Ltd.) as a TiO ₂ source. Manufactured by Kishida Chemical Co., Ltd.) and ZrOCl ₂ (manufactured by Kishida Chemical Co., Ltd.) as a ZrO ₂ source, and Ekinen F-1 (manufactured by Kishida Chemical Co., Ltd.) and water (purified water: Kishida Chemical Co., Ltd.) as a solvent.
Manufactured by the company) and the coating composition ratio is 30SiO ₂ · 40TiO ₂
It was prepared to be 30 ZrO ₂ (wt%).

Next, 1 well washed with water, detergent and ceria
A DK43-type blower-controlled incubator (Yamato Scientific Co., Ltd. )
(Made by Yamato Scientific Co., Ltd.) for 10 minutes after drying.
Heat treatment is carried out for 1 minute, the film thickness is 120 nm, the contact angle to water is 92 °, and the film composition is 30 SiO ₂ .40Ti.
A glass coated with a photocatalytic film of O ₂ .30ZrO ₂ (wt%) was obtained.

[Evaluation Result] The obtained glass with a photocatalyst film was evaluated by the method described above, and as shown in Table 1,
The photocatalytic activity was as high as 19, and it had a sufficient film hardness. Also, the contact angle with water is 91 °.
And showed water repellency. The Ra value was 5.9 nm, the film thickness was 105 nm, and the refractive index was 1.65. Figure 1 SEM
As shown in the photograph (50,000 times) and the AFM image photograph (2.5 μ square) in FIG. 2, it was observed that the film surface had fine irregularities. Further, the refractive index (SiO ₂ <quartz glass>: 1.456, TiO ₂ <anatase crystal>: 2.5
5, calculated from ZrO ₂ : 1.9)
The porosity is about 34%, and the inside of the film is porous, which increases the specific surface area of the film, and as a result,
It was assumed that the hardness of the film did not decrease so much and the area in which the photocatalytic reaction occurred was increased, and the catalytic activity was improved.

[0035]

[Table 1]

Example 2 Example 1 was repeated except that the composition ratio of the coating film was changed to 70SiO ₂ .30TiO ₂ (wt%). The obtained glass with a photocatalyst film was evaluated by the method described above. As a result, the contact angle to water was 90 °, which showed water repellency, and the photocatalytic activity was 13 and showed a high activity, and also had a high film hardness. .

Example 3 The same procedure as in Example 1 was carried out except that the composition ratio of the coating film was 50SiO ₂ .50TiO ₂ (wt%). The obtained glass with a photocatalyst film was evaluated by the method described above. As a result, the contact angle to water was 90 °, which showed water repellency, and the photocatalytic activity was 24, which showed a high activity and a high film hardness. .

Example 4 Instead of the heat treatment temperature of 300 ° C. in Example 1, 620 was used.
The same procedure as in Example 1 was carried out except that the heat treatment was carried out at ° C. As a result of evaluating the obtained glass with a photocatalyst film by the method described above, the photocatalyst activity was as high as 18, and the film hardness was also high. In addition, despite the heat treatment at a high temperature of 620 ° C., the contact angle to water was 89 °, which showed water repellency, and the photocatalytic activity was 18, which was almost the same value as that of Example 1. It is considered that this is because the photocatalyst film was porous and could prevent migration of alkali in the glass even when heat-treated at high temperature.

Comparative Example 1 Tetraethoxysilane (TEO) was used as a raw material for the SiO ₂ source.
Example 1 except that only S, manufactured by Kishida Chemical Co., Ltd. was used.
I went the same way. The obtained glass with a photocatalyst film was evaluated by the method described above. As a result, the glass having a high film hardness had a small contact angle with water of 5 ° and had a very low photocatalytic activity of 5. The Ra value is 2.5 nm and the film thickness is 1
The refractive index was 08 nm and the refractive index was 1.75. In addition, Example 1
Similarly, the porosity of the membrane is calculated to be 24%,
The value was considerably smaller than that in Example 1.

Comparative Example 2 Tetraethoxysilane (TEO) was used as a raw material for the SiO ₂ source.
Example 2 except that only S, manufactured by Kishida Chemical Co., Ltd. was used.
I went the same way. The obtained glass with a photocatalyst film was evaluated by the method described above. As a result, the glass having a high film hardness had a small contact angle with water of 3 ° and a very low photocatalytic activity of 1.

Comparative Example 3 Tetraethoxysilane (TEO) was used as a raw material for the SiO ₂ source.
Example 3 except that only S, manufactured by Kishida Chemical Co., Ltd. was used.
I went the same way. The obtained glass with a photocatalyst film was evaluated by the method described above. As a result, the glass having a high film hardness had a small contact angle with water of 5 ° and had a very low photocatalytic activity of 3.

[0042]

The photocatalyst film obtained by the present invention is made of Ti
The specific surface area of the photocatalyst film can be improved by incorporating a SiO ₂ component for exhibiting a photocatalytic action in the absence of ultraviolet light or a weak ultraviolet light intensity together with the O ₂ component and using trialkoxysilane as a raw material of the SiO ₂ source. In addition to enhancing the photocatalytic ability of the coating, the alkoxy group also exhibits water repellency and has the effect of enhancing durability such as abrasion resistance.

[Brief description of drawings]

FIG. 1 is a surface SEM photograph of a photocatalyst film of Example 1.

2 is a surface AMF image photograph of the photocatalyst film of Example 1. FIG.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C03C 17/02 C03C 17/02 B 17/25 17/25 A C09D 5/00 C09D 5/00 Z C09K 3 / 18 101 C09K 3/18 101 F term (reference) 4G059 AA01 AB09 AC22 CA01 CB05 EA04 4G069 AA03 AA08 BA02A BA02B BA04A BA04B BA05A BA05B BA14A BA14B BA21C BA48A BE32C CA01 CA10 CA11 CA17 EB03 ED01 ED03 FA03 FB23 FB30 FB66 FC02 FC07 FC08 4H020 BA03 4J038 DL031 HA216 HA446 KA04 KA12 KA20 NA02 NA05 NA07 NA18 PA19 PB07 PC03

Claims (7)

[Claims] 1. A photocatalyst film formed on the substrate surface, at least consists of SiO ₂ as a TiO ₂ crystal particles and the film-forming component as a photocatalyst, trialkoxysilane as a raw material for the SiO ₂ source (R1-Si ( OR2) ₃ ) (However,
A photocatalytic film having water repellency formed by a coating liquid of R1 and R2: which represents an alkyl group having 1 or more carbon atoms. 2. The photocatalyst film according to claim 1, wherein the content of the TiO ₂ crystal fine particles is 10 to 70% by weight and the content of SiO ₂ is 30 to 90% by weight. 3. The photocatalyst film has a TiO ₂ crystal fine particle content of 25 to 45% by weight, a SiO ₂ content of 30 to 50% by weight, and a ZrO ₂ content of 25 to 60% by weight. The photocatalyst film according to claim 1 or 2. 4. The photocatalyst film according to claim 1, wherein the photocatalyst film has irregularities on the film surface and voids inside the film. 5. The photocatalyst film for automobile glass according to claim 1. 6. TiO ₂ crystal fine particles and SiO ₂ are formed on the surface of a substrate.
Trialkoxysilane (R1-Si as a raw material of the source
(OR2) ₃ ) (wherein R1 and R2 are alkyl groups having 1 or more carbon atoms) are applied to form a film, and then 1
A method for producing a photocatalytic film, which comprises forming a water-repellent photocatalytic film having unevenness on the film surface and voids inside the film by performing heat treatment at 00 ° C to 650 ° C. 7. The photocatalyst according to claim 6, wherein the substrate with the photocatalyst film is bent and / or strengthened into a predetermined shape by heat treatment at a temperature of 560 to 650 ° C. after forming the film. Membrane manufacturing method.