JPH0797237A - Formation of transparent coating film reduced in refractive index - Google Patents

Abstract

PURPOSE:To form a thin film having refractive index of approx. <=1.7 on the surface of a glass plate by the thermal decomposition of a film-forming solution. CONSTITUTION:A film-forming solution containing an organometallic compound and a organosilicon compound with the molar ratio of the silicon to the metal being 3-60 or 3-24 when the metal is zirconium or tin, respectively, is fed on the high-temperature surface of a glass plate. With this method, an oxide thin film having 1.55-1.71 of refractive index can be formed on a large quantity and large-area of glass plates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an oxide film on a glass plate surface by utilizing thermal decomposition.

[0002]

2. Description of the Related Art In flat glass used for construction vehicles, functional aspects such as antireflection and solar radiation inflow control and aesthetic aspects by adjusting the reflectance and reflection spectrum in the visible range are emphasized. Since it has a great influence, the optical characteristics of glass have been conventionally adjusted by forming thin films having various refractive indexes on the surface of the plate glass. A typical example is heat-reflecting glass that has a mirror-like appearance and restricts the inflow of solar radiation into the internal space.

Further, recently, a building utilizing the transparency of glass has been reviewed, and a windshield of an automobile is required to have a visible light transmittance of a certain value or more for safety. Therefore, the demand for a thin film having a refractive index closer to that of the glass serving as the substrate is expanding more than ever before.

On the other hand, the method for forming a thin film on a glass substrate is
Although there are methods such as a sputtering method, a CVD method, and a sol-gel method, the method that can form a thin film on a large amount of a large amount of glass at the lowest cost is a film forming solution on a glass plate surface formed on a glass manufacturing line. Is a method of thermally decomposing the film-forming solution by a spray method or the like.

As a thin film formed by this method and having a refractive index relatively close to 1.5 which is a refractive index of soda lime silicate glass which is often used as a glass substrate, a silicon compound and a titanium compound are used as an organic solvent. There is a titanium oxide thin film containing silicon oxide formed by spraying a dissolved film forming solution on a plate glass on a line (Japanese Patent Publication No. 56-18547).

[0006]

However, the titanium oxide thin film containing silicon oxide formed by the above-mentioned invention is
The refractive index cannot be brought close enough to that of soda lime silicate glass.

[0007] Further, according to what the inventor has tried,
In the film forming method by thermal decomposition of the film forming solution, even if an organic silicon compound alone is contained in the film forming solution to form a film consisting of only silicon oxide, the film is not formed in order to reduce the refractive index. Or, it was in the form of white particles, and no preferable product was obtained.
This is because the reactivity of the organosilicon compound on the glass surface is low and a uniform film cannot be formed.

In view of such circumstances, the present invention has a refractive index of 1.7 which is closer to that of soda lime silicate glass.
It is an object of the present invention to provide a method for forming a thin film having a thickness of not more than a certain degree by thermally decomposing a film forming solution.

[0009]

The above object of the present invention can be achieved by the following constitutions.

The present invention is a method for forming an oxide film by supplying a film-forming solution containing an organometallic compound and an organosilicon compound onto a glass plate surface heated above the thermal decomposition temperature of the film-forming solution. The organometallic compound is an organozirconium compound, and the molar ratio of silicon to zirconium in the film-forming solution is 3 to 60, which is a method for forming a zirconium oxide-containing silicon oxide film.

The second aspect of the present invention is to form an oxide film by supplying a film-forming solution containing an organometallic compound and an organosilicon compound onto a glass plate surface heated above the thermal decomposition temperature of the film-forming solution. Wherein the organometallic compound is an organotin compound, and the molar ratio of silicon to tin in the coating film forming solution is 3 to 24. .

Here, it is desirable that the temperature of the glass surface is usually 450 ° C. to 650 ° C. This is because if the temperature is 650 ° C. or higher, the glass surface becomes uneven, which is not desirable as a product in appearance, and if it is 450 ° C. or lower, the film performance deteriorates.

Considering such temperature conditions and productivity of thin film formation, a spray for spraying the film forming solution onto a glass ribbon in a plate glass manufacturing process represented by a float method by using at least one spray gun. Law is desirable.

As the zirconium and tin compounds at this time, metal chelate compounds such as acetylacetonate and acetate, and inorganic compounds such as chlorides can be used.

On the other hand, as the organosilicon compound, one alkoxy group exemplified by tetramethoxysilane (hereinafter referred to as "TMOS"), tetraethoxysilane (hereinafter referred to as "TEOS"), tetrapropoxysilane, dimethylethoxysilane, etc. 4 alkoxy alkoxysilanes such as alkoxy monosilane, alkoxy disilane, alkoxy trisilane, and alkoxy tetrasilane, or an alkoxysilane derivative obtained by substituting a part of hydrogen of the alkoxysilane with a vinyl group can be used.

As the organic solvent, alcohols such as methanol and ethanol, carboxylic acids such as formic acid and acetic acid and esterified compounds thereof, aromatic hydrocarbons such as xylene and toluene, or amines are used.

The composition of the film-forming solution is determined by the required characteristics of the film to be formed. Since the compound concentration of zirconium and tin has a great influence on the film forming rate, it is determined from the solubility of the compound in an organic solvent and the desired film thickness of the film. On the other hand, since the concentration of the organosilicon compound has a great influence on the refractive index of the coating, it is determined from the required refractive index of the coating.

The higher the ratio of silicon to zirconium or tin in the film-forming solution, the lower the refractive index of the film, but if this ratio exceeds a certain value, a thin film excellent in transparency and uniformity can be obtained. Therefore, this ratio must be within a certain range.

The range of this ratio varies depending on the organometallic compound used, but if zirconium is 3 to 60 and tin is 3 to 24, the refractive index is about 1.7 or less, which is close to the refractive index of soda lime silicate glass. It is possible to obtain a transparent and uniform thin film having a high rate.

This range also changes depending on the organosilicon compound used. For example, when TEOS is used rather than TMOS, the upper limit of the above ratio can be increased. However, since the refractive index of the formed film changes depending on the organic silicon compound used, the refractive index is not uniquely determined by the above ratio. For example, when TMOS is used as the organosilicon compound, the refractive index of the film is lower than when TEOS is used.

[0021]

According to the present invention, the organic silicon compound and the organic zirconium compound or the organic tin compound are thermally decomposed on the glass to form an oxide film containing silicon and zirconium or tin, and have transparency and uniformity. A low refractive index coating is formed.

Further, the refractive index of the coating film can be adjusted by adjusting the ratio of silicon to zirconium or tin within a certain range in which transparency and the like are not lost.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following examples based on the drawings, but the present invention is not limited to the following examples.

(Embodiment 1) The transfer roll 5 is provided between the float bath outlet of the float glass manufacturing apparatus and the annealing furnace.
On the upper surface of the glass sheet 1 moving on the line at a speed of 12.7 m / min.
A toluene solution containing EOS was sprayed at an air pressure of 4 kg / cm ² and a liquid amount of 1000 ml / min to form a film on the plate glass 1. During film formation, exhaust was performed by the exhaust device 4 installed before and after the atomizing device 3 on the line.
The surface temperature of the plate glass 1 was 600 ° C.

Further, the film formation was carried out by changing the molar ratio of silicon to tin in the film forming solution, and the refractive index of the obtained film was measured by an ellipsometry apparatus using a laser having a wavelength of 632.8 nm. It was measured using. Table 1 shows the refractive index of the obtained coating.

[0026]

[Table 1]

Example 2 A film was formed under the same conditions as in Example 1 except that zirconium acetylacetonate was used in place of the dioctyltin diacetate of Example 1. Also at this time, the film formation was carried out by changing the molar ratio of silicon to zirconium in the film forming solution, but if this molar ratio exceeded 60, a uniform thin film could not be obtained. The refractive index of the obtained coating was measured by the same method as in Example 1. The results are shown in Table 1.

Further, in order to confirm that the coating film of the present invention has practically sufficient durability, the silicon oxide-containing zirconium oxide coating film of this example was subjected to an abrasion resistance test, an acid resistance test and an alkali resistance test. Carried out.

The abrasion resistance test is performed by the Taber test (friction ring C
S-10F, weight 500g, 1000 rotations), and the difference in haze ratio before and after the test was measured.

The acid resistance test was carried out by immersing the sample in a 5N sulfuric acid aqueous solution at 23 ° C. for 6 hours, and the difference in visible light reflectance before and after the test was measured.

The alkali resistance test was carried out by immersing the solution in 5N potassium hydroxide aqueous solution at 23 ° C. for 6 hours, and the difference in visible light reflectance before and after the test was measured.

The results are shown in Table 2.

[0033]

[Table 2]

Example 3 A film was formed under the same conditions as in Example 1 except that zirconium acetylacetonate was used in place of dioctyltin diacetate in Example 1 and TMOS was used in place of TEOS. At this time, a film was formed by changing the molar ratio of silicon to zirconium, but when this molar ratio exceeded 22, a uniform thin film could not be obtained.

The refractive index of the obtained coating was measured by the same method as in Example 1. The results are shown in Table 3.

[0036]

[Table 3]

From the comparison with the results of Example 2, the ratio of silicon to zirconium in the film forming solution cannot be increased when TMOS is used as compared with when TEOS is used as the organic silicon compound. As a result, it can be seen that a thin film having a low refractive index can be formed.

It is presumed that this is because TMOS has higher reactivity than TEOS, and a large amount of Si element is incorporated into the film to lower the refractive index.

Comparative Example 1 For the purpose of comparison with the present invention, a film containing titanium was formed on a trial basis.

Titanium acetylacetonate was used in place of the dioctyltin diacetate of Example 1, and the coating was formed under the same conditions as in Example 1 except for the above.

The refractive index of the obtained coating was also measured by the same method as in Example 1. The results are shown in Table 3.

[0042]

According to the present invention, a film having a refractive index of 1.55 to 1.71 can be formed on the surface of a large amount of glass having a large area by utilizing thermal decomposition.

The refractive index can be easily adjusted by adjusting the film forming solution within the above range.

The glass coated with the present invention can be used for construction, etc., but since the content of silicon oxide in the coating is high, it can be used in various applications where a silicon oxide coating is formed. It is available. While it is difficult to produce a film made only of silicon oxide by thermal decomposition such as spraying,
This is because the coated glass according to the present invention can be produced by thermal decomposition such as spraying.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a manufacturing apparatus for carrying out the present invention.

[Explanation of symbols]

 1; Sheet glass, 2; Film forming solution, 3; Atomizing device, 4; Exhaust device, 5; Conveying roll

Claims (3)

[Claims] 1. A method for forming an oxide film by supplying a film-forming solution containing an organometallic compound and an organosilicon compound onto a glass plate surface heated above the thermal decomposition temperature of the film-forming solution, said method comprising: The method for forming a zirconium oxide-containing silicon oxide coating film, wherein the organometallic compound is an organozirconium compound, and the molar ratio of silicon to zirconium in the coating film forming solution is 3 to 60. 2. The film forming method according to claim 1, wherein the organosilicon compound is tetramethoxysilane, and the molar ratio of silicon to zirconium in the film forming solution is 3 to 22. 3. A method for forming an oxide film by supplying a film-forming solution containing an organometallic compound and an organosilicon compound onto a glass plate surface heated above the thermal decomposition temperature of the film-forming solution, the method comprising the steps of: The method for forming a tin oxide-containing silicon oxide coating film, wherein the organometallic compound is an organotin compound, and the molar ratio of silicon to tin in the coating film forming solution is 3 to 24.