JPH06219785A - Water repellent glass having high abrasion resistance - Google Patents

Abstract

PURPOSE:To obtain water repellent glass having high abrasion resistance without impairing the transparency of the glass by forming a thin film of a nitride and/or a carbide with hardly any content of oxygen in the topmost surface part of the glass. CONSTITUTION:This water repellent glass has a layer of a nitride and/or a carbide, having at least 1nm thickness and respectively containing 0-20mol% oxygen in the topmost surface part. The layer of the nitride and/or carbide is preferably a nitride, carbide, an oxygen-containing nitride or an oxygen- containing carbide of a metal such as silicon, boron, aluminum, titanium, zirconium, chromium, nickel or zinc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to water-repellent glass, especially
The present invention relates to a water-repellent glass having high wear resistance, which can be applied to a wide range of applications such as construction and automobiles.

[0002]

2. Description of the Related Art At present, most of organic substances centered on silicon compounds have been developed as water-repellent substances for coating the surface of glass or the like. In general, these are linear siloxane polymers, and have a structure having an organic functional group such as a methyl group in the side chain to increase the contact angle with water.

On the other hand, in recent years, it has been recognized that an organic-inorganic composite can be produced by the sol-gel method, and its application is as follows.
For example, research by Tsuchiya et al. (Japan Ceramic Society 1991
As shown in Annual Meeting, Lecture No. 1D-18), a water-repellent film is being developed. In this method, a fluorine-based compound is added to a solution containing tetramethoxysilane to form an organic-inorganic composite film on a glass substrate.

[0004]

When the above-mentioned silicon compound is applied to a glass substrate to form a water-repellent glass, these compounds and the glass substrate do not form a bond, so that this film easily flows out during use. It loses its water repellent effect. Further, even in the initial state, the film itself is weak and soft, so that the abrasion resistance is low.

The film obtained by the sol-gel method has improved durability as compared with the film made of the water-repellent organic compound, but has poor abrasion resistance because it is porous, and the organic substance is uniformly dispersed. However, there is a problem that the water-repellent effect is recognized only on the outermost surface.

The present invention significantly improves the low abrasion resistance, which is a drawback of the conventional water repellent materials described above, and has high abrasion resistance without impairing the transparency of the glass. The purpose is to provide.

[0007]

[Means for Solving the Problems] The present inventors have earnestly studied water-repellent thin films on glass and studied the water-repellent properties of various materials. As a result, oxygen near the outermost surface of the glass substrate We have found that hydrogen bonds easily form with the water droplets above, and this hydrogen bonding makes it difficult for water droplets on the glass surface to move. This phenomenon does not significantly affect the water repellency that is generally evaluated, that is, the contact angle, that is, the angle between the water droplet on the glass substrate and the glass substrate, but the falling angle, that is, the inclination of the glass substrate. This causes an increase in the minimum angle at which water droplets on the glass substrate start to move, which is a serious problem in practical use.

From these findings, the present inventors have concluded that in order to improve the water repellency, especially the sliding angle, it is sufficient to form a thin film having a low oxygen content on the outermost surface of the glass. .

Continuing research to put this idea into practice, the present inventors most preferably form a thin film of either an oxygen-containing nitride or carbide, or a mixture thereof on a glass substrate. I reached the conclusion. It is already known that these compounds have higher bond strength, higher strength, and higher wear resistance than oxides of the same metal element. Therefore, the glass substrate having such a film formed on the outermost surface can realize not only high water repellency but also high abrasion resistance.

That is, according to the present invention, the outermost surface has at least 1
A highly abrasion-resistant water-repellent glass having a nitride or / and carbide layer each having a thickness of nm and containing 0 to 20 mol% of oxygen.

The nitride or / and carbide layer containing 0 to 20 mol% of oxygen in the present invention is specifically a metal such as silicon, boron, aluminum, titanium, zirconium, chromium, nickel or zinc. Of these, nitrides, carbides, oxygen-containing nitrides or oxygen-containing carbides are more effective. Of course, these do not necessarily have to be used alone, and two or more kinds may be mixed.

According to the findings of the inventors of the present invention, it is clear that it is more preferable that oxygen in the vicinity of the outermost surface is as small as possible. However, forming pure nitride or carbide containing no oxygen on a glass substrate is
Practically difficult. These compounds obtained by usual glass forming methods, more specifically by sputtering or thermal decomposition of organometallic compounds, almost always contain oxygen due to the high activity of oxygen. Then, as a result of examining the allowable limit oxygen amount, the present inventors have concluded that the limit is 20 mol%, more preferably 10 mol%. A film containing a larger amount of oxygen than this does not show any improvement in water repellency. There is no lower limit to the oxygen content,
As indicated above, the lower the lower the better.

The thickness of the nitride or / and carbide thin film in the present invention is preferably as thick as possible from the above knowledge, but is preferably thin in manufacturing. Considering the strength of water droplets and hydrogen bonds on the glass surface, a thickness of 1 nm or more is substantially sufficient. If it is thinner than this, separation of water droplets and oxygen on the glass surface is not sufficient, hydrogen bonding between water droplets and oxygen in the film cannot be ignored, and the sliding angle is not sufficiently improved. From the viewpoint of manufacturing, the thickness is preferably 500 nm or less. Various methods are conceivable for forming these thin films on a glass substrate, but are not particularly limited, and specifically, a sputtering method in a nitrogen atmosphere, thermal decomposition of an organometallic compound polymer such as polysilazane, etc. The law and the like are exemplified.

The refractive index of nitride or carbide is
Since it is usually larger than a glass substrate, it is possible to improve the optical characteristics such as improving the reflectance and imparting a specific color by appropriately controlling the composition or thickness of the film. Alternatively, even if the film thickness is controlled, there is no problem in the water-repellent property as long as the disclosure of the present invention is satisfied.

[0015]

EXAMPLES Examples will be shown below. Example-1 Thoroughly washing a 10 cm square 3 mm thick normal float glass,
After drying, it was placed in a vacuum chamber. The atmosphere was replaced with nitrogen from the atmosphere before the vacuum was applied. It was deaerated with a vacuum pump to 10 ^-3 torr or less. Commercially available silicon nitride was prepared as a target and sputtered at a discharge current of 3.0 amperes. The obtained glass substrate had a slightly higher refractive index, but was a transparent substrate. As a result of observing the cross section, the film thickness was 10 nm, and the oxygen content was 8 mol% in the ESCA measurement result.

On this substrate, 0.05 g of pure water was dropped and the contact angle and the falling angle were measured. The former was measured using a commercially available contact angle measuring device. The latter was evaluated by slowly inclining the glass substrate and measuring the inclination angle at the moment when the water droplets on the glass surface started to move. The measurement result of this substrate was that the contact angle was 95 degrees and the sliding angle was 28 degrees.

The abrasion resistance was measured by the Taber test method. In this method, a rubber roller was pressed against a glass substrate with a load of 1 kg and rubbed, and the abrasion resistance was evaluated by comparing the values before and after the test. This time, the rotation speed was set to 1000 times.

With respect to the respective values after the Taber test of this substrate, the contact angle was 98 degrees and the sliding angle was 23 degrees, and the water repellency was improved as compared with that before the abrasion resistance test. This is probably
It is considered that in the abrasion resistance test, the outermost surface layer that adsorbed oxygen in the atmosphere disappeared, and silicon nitride with less oxygen appeared on the surface.

Comparative Example-1 A silicon nitride thin film was formed on a glass surface under the same conditions as in Example-1 above, but oxygen was introduced into the sputtering atmosphere instead of nitrogen. As a result, the oxygen content of the obtained silicon nitride film was 30 mol%.

When the contact angle and the sliding angle of this film were measured, they were 45 ° and 50 °, respectively, and no significant improvement was observed in comparison with the ordinary glass substrate.

Example 2 Commercially available polysilazane solution (content: 10% by weight, solvent: T
A washed and dried 10 cm square glass substrate was immersed in HF), pulled up at a rate of 3 cm / min, and dried at 80 ° C. to form a thin film. This glass substrate was heat-treated at 400 ° C. for 4 hours in a nitrogen atmosphere to obtain silicon nitride. This silicon nitride thin film had a thickness of 20 nm and an oxygen content of 5 mol%.

When the water repellency of this film was evaluated, the contact angle was 105 degrees and the falling angle was 20 degrees.

Example-3 Using chromium nitride as a target, a film was formed on a glass substrate under the same conditions as in Example-1. From the observation of the cross section, the film thickness is 250 nm, and from the ESCA measurement, the oxygen content is 1
It was 0 mol%.

When the water repellency of this film was evaluated, the contact angle was 102 degrees and the sliding angle was 22 degrees. When abrasion resistance was evaluated under the same conditions as in Example-1, there was almost no change. Note that this film had a very high refractive index, and therefore this sample had a half-mirror-like appearance.

Comparative Example-2 50 ml of commercially available tetramethoxysilane (TMOS) was dissolved in 450 ml of ethanol, and 5 ml of 1N hydrochloric acid was added to the solution for hydrolysis. To this solution, trifluoropropyltrimethoxysilane, CF ₃ CH ₂ CH ₂ Si (OCH ₃ )
₃ , 0.5 ml was further added.

A well washed and dried 10 cm square glass substrate was dipped in this solution and pulled up at a rate of 3 cm / min to obtain 8
It dried at 0 degreeC and produced the thin film. This glass substrate,
It heat-processed at 400 degreeC in air | atmosphere for 2 hours. When the water repellency of the obtained film was evaluated, the contact angle was 99 degrees and the sliding angle was 30.
And good water repellency.

Abrasion resistance was evaluated under the same conditions as in Example 1, but after the Taber test, almost no film remained on the glass surface, and therefore the water-repellent property was only about that of ordinary glass. It was

[0028]

According to the present invention, a glass substrate having improved water repellency, particularly a falling angle, and extremely high abrasion resistance, as compared with a conventional water repellent glass substrate, can be easily and efficiently manufactured. Can be manufactured.

Claims (3)

[Claims] 1. A highly wear-resistant water-repellent glass having a nitride or / and carbide layer having a thickness of at least 1 nm and each containing 0 to 20 mol% of oxygen on the outermost surface. 2. The nitride is a nitride of at least one metal selected from the group consisting of silicon, boron, aluminum, titanium, zirconium, chromium, nickel, and zinc, or an oxygen-containing nitride. The water-repellent glass having high abrasion resistance according to 1. 3. The carbide according to claim 1, which is a carbide of at least one metal selected from the group consisting of silicon, boron, aluminum, titanium, zirconium, chromium, nickel, and zinc, or an oxygen-containing carbide. Water-repellent glass with high abrasion resistance.