JPH10219461A - Water-repellent ceramic coating film and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a coating film which almost permanently maintains the initial water repellency without maintenance by incorporating molecules having fluoroalkyl groups and titanium oxide into an oxide film of at least one of Si, Al, Ti, Zr, Sn and W. SOLUTION: A coating soln. containing a hydrolysate of fluoroalkyl methoxysilane or fluoroalkyl ethoxysilane, titanium oxide particles, and at least one hydrolysate of alkoxide compd. of Si, Al, Ti, Zr, Sn or W is applied on a base body and calcined. The obtd. water-repellent ceramic coating film contains molecules 3 having fluoroalkyl groups and titanium oxide 4. Some of titanium oxide particles 4 are exposed on the surface of the water-repellent ceramic coating film and decompose org. molecules depositing on the surface of the photocatalytic effect. Thereby, since the surface by the film is not coated with org. molecules, the film maintains its water repellency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-repellent ceramic coat film and a method for producing the same.

[0002]

2. Description of the Related Art A water-repellent ceramic coating film is a coating film having hardness and abrasion resistance comparable to ceramic and water repellency comparable to fluororesin. As the water-repellent ceramic coat film, for example, the following three techniques can be mentioned as conventional techniques.

The first one is disclosed in Japanese Patent Application Laid-Open No. 4-136181.
The water-repellent ceramic coat film is made of Al, Zr, Ti,
It is configured to be contained in one kind or two or more kinds of oxide films of Si, W, Ce, Sn and Yn.

The second is tetraethoxysilane (Si)
(OCH ₃ ) ₄ ; hereinafter abbreviated as TEOS) and perfluoroalkylmethoxysilane (CF ₃ (CF ₂ ) ₇ C ₂ H ₄ S
After adding water and hydrochloric acid to an ethanol solution in which i (OCH ₃ ) ₃ ) is dissolved, a coating solution obtained by hydrolyzing these compounds is applied to glass, and baked at 400 ° C. to form a water-repellent ceramic coating film. (Takao Kamigami et al., Tokyo Metropolitan Industrial Technology Center Research Report No. 22, 1993).

The third is tetraethoxysilane (Si)
After adding water and a hydrochloric acid catalyst to an ethanol solution of (OCH ₃ ) ₄ ), polyethylene glycol was added thereto, and the solution was coated on glass.
At the same time as firing at ℃ to polymerize the tetraethoxysilane, burning the polyerylene glycol to form a porous silica glass on the glass, then diluting the fluoroalkyltrimethoxysilane with methanol and removing the water In addition, a partially hydrolyzed solution is applied to the above glass and then fired at 400 to 600 ° C. to produce a water-repellent ceramic coat film (Ceramics, Vol. 29, No. 6, page 533, 1994). .

[0006]

However, the substrate coated with the above-mentioned conventional water-repellent coat film has a problem that the water-repellency of the substrate surface is reduced when exposed to a dusty environment for a long time. Exists. This is because organic molecules floating in the air adhere to the surface of the coat film, and the surface of the water-repellent coat film is covered with the above-described organic molecules, so that sufficient water repellency cannot be obtained. ing. In addition,
The organic molecules are dust and the like in a room, and are exhaust gas and the like in a car outside.

Here, when the substrate having lost water repellency is washed with a surfactant or the like, organic substances on the surface of the coat film are removed from the film surface, and the substrate can recover the initial water repellency.

However, in order to maintain the water repellency of the conventional water repellent ceramic coat film, it is necessary to periodically perform maintenance such as cleaning as described above.

In view of the above problems, the present invention maintains the water repellency in the initial stage of the coating film almost semipermanently by exposing the coating film to light for a certain period of time without regular maintenance. An object of the present invention is to provide a water-repellent ceramic coat film and a method for producing the same.

[0010]

In order to achieve the above-mentioned object, the water-repellent ceramic coating film of the present invention comprises Si, A
at least one of l, Ti, Zr, Sn or W
The structure is such that one oxide film contains a molecule containing a fluoroalkyl group and titanium oxide particles.

Further, the method for producing a water-repellent ceramic coat film of the present invention is characterized in that a hydrolyzate of fluoroalkylmethoxysilane or fluoroalkylethoxysilane, titanium oxide particles, and Si, Al, Ti, Zr, Sn or W A coating solution containing at least one hydrolyzate of an alkoxide compound is applied to a substrate and then fired.

With this configuration, since the water-repellent ceramic coat film of the present invention contains titanium oxide, the attached organic molecules can be decomposed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The water-repellent ceramic coat film of the present invention contains a component for decomposing organic molecules which adhere when the water-repellent ceramic coat film is exposed to the outside air and a molecule having a fluoroalkyl group. It is characterized by the following. The above components are Si, Al, Ti, Z
One of r, Sn, and W is contained in the oxide film containing two or more kinds. Here, it is very difficult to find a material that decomposes organic molecules, but the present inventors have found that a substrate requiring water repellency is usually placed in a place where light is irradiated. Focusing on the fact that this is often the case, a material that decomposes organic molecules by light (ultraviolet) irradiation was included in the water-repellent ceramic coat.

The present inventors dispersed titanium oxide particles having an anatase structure having high photocatalytic activity as a substance having the above-mentioned properties in a water-repellent ceramic coat film. This means that some of the titanium oxide particles are present on the surface of the coating film.However, since the titanium oxide particles have a property of decomposing organic substances under ultraviolet rays, under light irradiation, In addition, the surface of the water-repellent ceramic coat film is always kept free of organic substances, and as a result, the initial water-repellency can be maintained without washing or the like.

Hereinafter, the water-repellent ceramic coat film according to the embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view when a water-repellent ceramic coat film 1 according to the present embodiment is formed on a substrate 2, and FIG. 2 is an enlarged cross-sectional view of a region A in FIG. It is shown. In FIG. 2, the water-repellent ceramic coat film of the present invention contains titanium oxide 4 together with the molecule 3 having a fluoroalkyl group, and some of them are exposed on the surface of the water-repellent ceramic coat film. It is in a state where it has been done.

Next, the step of decomposing organic molecules when the organic molecules adhere to the water-repellent ceramic coat film having the structure shown in FIG. 2 will be described with reference to FIG.

First, as shown in FIG. 3A, organic molecules 5 adhere to the surface. Thereafter, as shown in FIG. 3B, the organic molecules are decomposed by the photocatalytic action of the titanium oxide 4 present on the surface of the water-repellent ceramic coat film. Note that FIG.
In (b), 6 is an organic molecule that is being decomposed by the photocatalytic action of titanium oxide, and its size is reduced. As a result, the organic molecules completely disappear as shown in FIG. In addition, the particle diameter of titanium oxide is 100
Desirably, it is not more than nm.

[0019]

Next, a water-repellent ceramic coat film and a method of manufacturing the water-repellent ceramic coat film in the embodiments of the present invention will be described in detail.

(Embodiment 1) In this embodiment, a component for decomposing organic molecules and a molecule having a fluoroalkyl group are contained in an oxide film of Si.

Si alkoxide which is a material for fixing a molecule having a fluoroalkyl group to a substrate, and a particle diameter of 7 n
As a solution containing about m of titanium oxide, a coating solution ST-K03 from Ishihara Techno Co., Ltd. was used. The solid concentration of this coating solution is 10% (weight ratio). This coating solution was diluted 3-fold (volume ratio) with an ethanol solution, and the fluoroalkylmethoxysilane (CF ₃ (CF ₂ ) ₇ C ₂ H) was added thereto.
₄ Si (OCH ₃ ) ₃ ) was dissolved. The concentration of the fluoroalkylmethoxysilane was 5% by volume. The volume of the prepared solution is 200 ml. As a result, a coating solution containing the hydrolyzate of the Si alkoxide compound, the titanium oxide particles, and the fluoroalkylmethoxysilane was formed.

Next, a slide glass of 5 cm × 5 cm × 2 mm was immersed in the solution at a speed of 2 mm / s so that the surface of 5 cm × 5 cm was perpendicular to the solution, and then the slide glass was 0.5 mm / s. Pull up at speed. Thereafter, the slide glass was dried at room temperature for 1 hour,
For 30 minutes. Hereinafter, the coated glass is referred to as Sample A. The static contact angle of the surface of the sample A with respect to pure water was 110 degrees, indicating water repellency equivalent to that of a fluororesin.

As a reference sample, a water-repellent ceramic coat film containing no titanium oxide particles was formed. This coat film was formed based on the method described above as a conventional technique.

Specifically, the following two solutions of α and β were prepared, and the solution β was added dropwise while stirring the solution α with a stirrer, followed by stirring for 60 minutes. Solution α contains 40 ethanol
g, 37 g of Si (OC ₂ H ₅ ) 4, CF ₃ (CF ₂ ) ₇ C ₂
H ₄ Si (OCH ₃ ) ₃ was mixed with 10 g, and the solution β was 40 g of ethanol, 10 g of water, and 1 g of hydrochloric acid.
It is a mixture.

Next, a slide glass of 5 cm × 5 cm × 2 mm was immersed in the solution at a speed of 2 mm / s so that a surface of 5 cm × 5 cm was perpendicular to the solution, and then the slide glass was 0.2 mm / s. Pull up at speed. Thereafter, the slide glass was dried at room temperature for 1 hour,
For 30 minutes. Hereinafter, the coated glass is referred to as a sample B. The static contact angle with respect to pure water on the surface of the sample B was 110 degrees, and showed the same water repellency as the water repellent ceramic coat containing titanium oxide.

Next, changes in water repellency with time of the samples A and B in a dusty environment were examined by the following two test methods.

As a first test method, the test was performed in a smoking room as shown in FIG. The size of this smoking room is 6 tatami mats and the height is 3 m. Twelve 30 W fluorescent lamps 7 are installed on the ceiling, and a ventilation fan 8 is installed on the wall to constantly ventilate the air in the room. Reference numeral 9 denotes a chair. In this room, an average of 50 people smoke daily. The above-mentioned samples A and B were hung on the wall of this room as 10 in FIG. Thus, the reason why the test was performed in the smoking room is that the smoking room emits light called fluorescent light,
Moreover, it is an environment in which organic molecules called cigarette tar are generated.

As a second test method, the test was carried out by hanging the above-mentioned samples A and B on the outer wall of a house near a national road having a very large traffic volume. The reason why the test was performed near the national road is that the outdoor environment near the national road is an environment in which light such as sunlight is irradiated and organic molecules called exhaust gas of automobiles are generated.

Next, the results of the above two tests are shown in the following table.

[0030]

[Table 1]

As is clear from the results shown in Table 1, the water-repellent ceramic coat film of the present invention can maintain the initial water-repellency for a long time without maintenance.

The ceramic coat of this embodiment is made of Si.
Is used for the coating film, the coating film is transparent, and a water-repellent coating can be applied to the substrate without impairing the base feel of the substrate.

Example 2 200 ml of an ethanol solution containing a protoxy compound of Al, Ti, Zr, Sn or W and fluoroalkylmethoxysilane (CF ₃ (CF ₂ ) ₇ C ₂ H ₄ Si (OCH ₃ ) ₃ ) Created. However, the mixing ratio between the protoxy compound and the fluoroalkylmethoxysilane was 10: 1 in molar ratio, and the total amount of the pentoxy compound and the fluoroalkylmethoxysilane was 30% (volume ratio) of the whole solution. To this solution, titanium oxide having a particle size of 7 nm
g dissolved. Next, in the same manner as in Example 1 described above, these solutions were coated on a slide glass and baked at 300 ° C. The static contact angles of these coat films to pure water were all 110 degrees. The results of the same test as in Example 1 are shown in the following table. This table shows the characteristics 300 days after the water-repellent treatment.

[0034]

[Table 2]

As is evident from the results shown in Table 2, the water-repellent ceramic coat film of the present invention was also used in this embodiment.
The initial water repellency can be maintained for a long time without maintenance.

Although the water-repellent ceramic coat film of the present invention has been described with specific examples, the water-repellent ceramic coat film of the present invention contains titanium oxide particles. At the same time, it has an antibacterial action for decomposing bacteria and microorganisms such as Escherichia coli on the surface of the base material. Therefore, the present invention can be applied to a cooking utensil, a tableware, a toilet bowl, a bathroom tile, a hospital wall, and other coat films which are desired to minimize the generation of bacteria. In addition, the water-repellent ceramic coat film of the present invention semi-permanently retains the initial water repellency without maintenance, so that maintenance is difficult, such as window glass of high-rise buildings, wall coatings, highways and uninhabited islands. It can also be applied as a coating film for lenses of observation cameras.

In the embodiment of the present invention, CF ₃ (CF ₂ ) ₇ C ₂ H ₄ S is used as a molecule having fluoroalkyl.
Although the water-repellent ceramic coat film was formed using i (OCH ₃ ) ₃ , the present invention is not limited to this, and molecules having a short alkyl fluoride chain, for example, CF ₃ (CF ₂ ) ₂ C ₂ H ₄ Si (OC
Needless to say, even if H ₃ ) ₃ is used, a coat film having the same characteristics as in this embodiment can be obtained. It goes without saying that a coat film similar to that of the embodiment can be obtained even when the molecule methoxy having a fluoroalkyl is an ethoxy group.

[0038]

As described above, since the water-repellent ceramic coat film of the present invention contains titanium oxide particles having a photocatalytic function, it can decompose organic substances attached to the surface of the coat film even in a dusty environment. Water repellency can be maintained almost semi-permanently.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view when a water-repellent ceramic coat film according to an embodiment of the present invention is formed on a substrate.

FIG. 2 is an enlarged view of a water-repellent ceramic coat film surface according to the embodiment of the present invention.

FIG. 3 is a schematic diagram showing a change over time of an organic substance attached to the surface of the water-repellent ceramic coat film in the embodiment of the present invention.

FIG. 4 is a schematic diagram of a smoking room in which a test of the water-repellent ceramic coat film of the present invention was performed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Water-repellent ceramic coating film 2 Base material 3 Fluoroalkyl group-containing molecule 4 Titanium oxide particle 5 Organic molecule 6 Organic molecule being decomposed by photocatalysis of titanium oxide 7 Fluorescent lamp 8 Ventilation fan 9 Chair 10 Sample

Claims (2)

[Claims] 1. The method according to claim 1, wherein the Si, Al, Ti, Zr, Sn, or W
A water-repellent ceramic coat film, wherein at least one of the oxide films contains a molecule containing a fluoroalkyl group and titanium oxide particles. 2. A hydrolyzate of fluoroalkylmethoxysilane or fluoroalkylethoxysilane, titanium oxide particles, and at least one hydrolyzate of an alkoxide compound of Si, Al, Ti, Zr, Sn, or W. A method for producing a water-repellent ceramic coat film, comprising applying the applied coating solution to a base material and then firing.