JP2001261373A - Method of forming thin film, and sheet glass with thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a thin film with a homogeneous film thickness on the surface of a belt-shaped sheet glass by a thermal spray method using plural spray guns at the outlet of a float bath. SOLUTION: When forming the thin film on the surface of a sheet glass by using plural spray guns, and reciprocally moving the spray guns so as to be synchronized while spraying the chemicals on the surface of the traveling sheet glass at a high temperature, the intervals and swinging widths of neighboring spray guns are regulated so as to be the same, and the moving speeds of the spray guns moving so as to cross the traveling direction of the sheet glass are regulated so as not to form unevenness in the thickness of the film. Further, a means for removing excess chemical mist which causes the unevenness of the thickness of the film is installed to remove the chemical mist.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a uniform film on a substrate to be sprayed by a spray.

According to the present invention, colored coating glass, half-mirror-shaped glass, ultraviolet-reflective glass, and heat-reflective glass used for window glass for buildings or vehicles, display window glass for electronic materials, and the like are manufactured by a thermal spray method. In particular, the present invention relates to a method for spraying a chemical solution from above a hot strip glass sheet moving in the longitudinal direction at the float bath outlet with a spray gun to form a thin film on the surface of the sheet glass.

[0003]

2. Description of the Related Art A colored coated glass having a colored film formed on the surface of a sheet glass, a half-mirror-shaped glass having a thin film that transmits semi-visible light and reflects the remainder, and a thin film that absorbs or reflects ultraviolet light or infrared light UV cut glass, heat ray reflective glass formed
It is commercially available as window glass for construction or window glass for automobiles.

As a method for obtaining these functional thin films on the surface of a glass sheet, a thin film made of a metal, a metal oxide, a metal nitride, or the like is formed on the surface of the glass sheet. There are a vapor deposition method (PVD method), a scientific vapor deposition method (CVD method), a liquid phase method, a thermal spray method, and the like.

[0005] As the PVD method, for example, a sputtering method, a vacuum evaporation method and the like are known. The PVD method is a method of forming a thin film on a glass substrate surface under a high vacuum,
Since a large-scale vacuum device is required, glass with a thin film manufactured by the PVD method is expensive. Furthermore, a thin film formed by the PVD method has poor scratch resistance.

In the CVD method, a continuous thin film can be formed during the manufacturing process of a sheet glass. When the CVD method is used, it is possible to continuously form a thin film on the surface of the moving strip-shaped plate glass immediately after leaving the float bath during the manufacturing process of the plate glass by the float method.

[0007] Since a thin film having excellent durability can be obtained by using the CVD method, it is used by many sheet glass manufacturers for producing a glass substrate with a thin film. However, in the CVD method, the equipment is expensive, and the usable raw materials are limited depending on the vapor pressure, the decomposition temperature, and the like, so that the type of the obtained thin film is limited.

In a method using an organic metal salt or the like such as a liquid phase method, for example, a sol-gel method, a thin film can be formed by a simple apparatus under normal pressure. In the liquid phase method, by a wet coating method, for example, a dipping method, a spin coating method,
On the surface of the glass sheet, to apply a chemical for forming a thin film, it is difficult to form a thin film on a large-sized glass substrate, in order to obtain scratch resistance to the formed thin film, after coating,
The coating film must be heated and cured at a high temperature.

On the other hand, the thermal spray method of forming a thin film by applying a chemical solution to the surface of a high-temperature plate glass by using a spray gun using a spray gun requires only a spray gun and its peripheral equipment. However, it is possible to provide a thin-plate glass sheet at a low cost.

[0010] Furthermore, the thermal spray method has a wide variety of chemical solutions that can be used, and can produce a sheet glass with a thin film having various functional thin films formed on the surface.

In the thermal spray method, an organic metal salt is added to an organic solvent.
Or spray the chemical solution with dissolved inorganic metal salt on the surface with a spray gun from above the high temperature plate glass,
This is a method in which an organic metal salt or an inorganic metal salt is thermally decomposed on the surface of a sheet glass to form a metal compound thin film on the surface of the sheet glass.

For example, when a thin film is formed on the float glass surface during the float glass manufacturing process, a chemical solution is sprayed from above onto a strip-shaped plate glass having a surface temperature of 500 ° C. to 600 ° C. from a float bath outlet. Then, the metal salt is instantaneously thermally decomposed to form a metal compound thin film on the surface of the glass sheet.

When a thin film is formed at a float bath outlet on a wide area of the surface of the strip-shaped glass sheet drawn out from the float bath, conventionally, one spray gun is separated from the strip-shaped glass sheet by a height of several tens cm. The spray gun is reciprocated so as to cross the movement of a high-temperature strip-shaped glass sheet moving at a constant speed, and sprayed over a desired wide area to form a thin film.

However, in a thermal spray method in which a chemical solution is sprayed on the surface of a moving high-temperature band-shaped glass sheet at the float bath outlet, and the chemical solution is thermally decomposed according to the temperature of the glass sheet to form a functional thin film on the surface. Normal,
One spray gun is reciprocated. When the spray gun is reciprocated, zigzag film thickness unevenness occurs on the surface of the glass sheet.

In the thermal spraying method, when a chemical is sprayed on the surface of a glass sheet by a spray gun to increase the area for applying the chemical, the swing width of the reciprocating spray gun is increased, and the moving speed is increased. And increase the amount of chemical solution discharged from the spray gun.

As a result, the zigzag film thickness tends to be uneven, and the zigzag film thickness unevenness becomes remarkable at both ends of the reciprocating motion of the spray gun. That is, the portion of the plate glass where the zigzag film thickness unevenness occurs is used. There was a disadvantage that it could not be done.

Also, when the chemical sprayed from the spray gun drifts as a mist and is not quickly exhausted, or when the air flow in the area where the chemical is sprayed is disturbed,
The thin film formed on the surface of the sheet glass has uneven film thickness or has a film defect.

In an optical thin film having a thickness of at most several hundred nm, a difference in thickness between a thick portion and a thin portion is one.
If the thickness slightly exceeds 0 nm, even if a thin film is formed on the glass surface by the thermal spray method, the absolute value of the film thickness difference is visible except at both ends of the region where the chemical solution is sprayed and applied with a spray gun. Since the film thickness is smaller than the wavelength of the light beam, the difference in film thickness, that is, the film unevenness cannot be visually recognized. However, if the difference in film thickness is 10 nm or more, visually noticeable film thickness unevenness occurs.

[0019]

As a method of solving the problem of the thermal spraying method, that is, a method of reciprocating a plurality of spray nozzles and controlling the moving speed in a sinusoidal wave as a method of making the film thickness uniform, It is disclosed in JP-A-51-101015.

In the method described in JP-A-51-101015, a plurality of spray guns are arranged at substantially equal intervals, and 0.38 ± 0.08 times or 0.84 times the interval between the spray guns in the width direction. ± 0.17 times, or 10.7 ± 0.
Move the spray gun in a sinusoidal shape with 27 times the amplitude,
This is a method for forming a uniform spray film.

However, even when the spray gun is moved in a sine wave shape, it is difficult to obtain a uniform film thickness on the surface of the plate glass when the chemical is sprayed with the spray gun.
Even if a spray gun alone can provide a uniform film thickness, even if a plurality of spray guns are arranged, a uniform film can be formed on the surface of the sheet glass due to the interaction due to interference between the spray guns, such as overlapping application areas. There is a problem that it is difficult to obtain a thick thin film.

Japanese Patent Application Laid-Open No. 7-10602 discloses that
The spray shape, which is the application shape when sprayed, is a round spray nozzle having a substantially circular shape, or a plurality of spray nozzles having a spray shape having a strip shape, that is, a long and narrow rectangular shape, and the spray nozzles are close to each other in the width direction of the band-shaped plate glass. A method of forming a uniform thin film by spraying a chemical solution while reciprocating the spray nozzles in the width direction of the plate glass in synchronization with the spray nozzles is disclosed.

However, when the spray nozzles are brought close to each other, the chemical sprayed by the spray gun at the center of the two adjacent spray nozzles evaporates near the surface of the high-temperature plate glass to form a chemical mist.
There has been a problem that the chemical mist interferes with each other, resulting in a portion having a high concentration in the air of the chemical mist, or a turbulence of the air flow above the plate glass, resulting in film unevenness.

That is, the chemicals sprayed by a plurality of spray guns are usually heated by a high-temperature band-shaped plate glass at 500 ° C. to 600 ° C., evaporate and expand, diffuse as chemical mist, and adjoin each other. After staying in the center of the spray gun, it rises.

An object of the present invention is to dispose a plurality of spray guns at a distance from a high-temperature strip-shaped glass sheet moving at the float bath outlet so as to spray a chemical solution while crossing the traveling direction of the strip-shaped glass sheet. In the thermal spray method in which a plurality of spray guns are moved to form a thin film on the surface of a glass sheet, the above problem is solved, that is, a thin film with uniform and few film defects is formed on the surface of the glass sheet.

[0026]

Means for Solving the Problems In the above-mentioned thermal spraying method for forming a thin film on the surface of a sheet glass by using a plurality of spray guns, the present inventors heated to 500 ° C. in order to obtain uniform thin film forming conditions. Above the horizontal glass plate,
One or a plurality of spray guns were fixed, and a chemical solution was sprayed by the spray gun for a very short time, and the thickness of a thin film formed on the surface of the plate glass was measured at multiple points.

The present inventors assume that the film thickness distribution obtained from the multi-point measurement of the film thickness is used as a basic pattern, and that the basic pattern is moved by a fixed minute distance. Was added to obtain a simulation of a film thickness distribution when a thin film was formed on the surface of a sheet glass by actually using a thermal spray method.

In the thermal spray method, a chemical liquid is sprayed while a spray gun is reciprocated in the width direction of a moving band-shaped plate glass, whereby a thin film is obtained on the surface of the plate glass.

That is, the present inventors use the film thickness distribution obtained from the above-described multi-point measurement of the film thickness as a basic pattern. In the thermal spray method, the spray gun is actually reciprocated to form the basic pattern. The glass surface is moved by moving the spray gun back and forth in the width direction of the band-shaped plate glass by moving it by a fixed minute distance along the width direction of the plate glass and adding the film thickness of the part where the basic pattern overlaps. Obtained by spraying a chemical solution on
Simulate the film thickness distribution of the thin film on the surface of the glass sheet,
Spray gun installation conditions and movement conditions that can obtain a more uniform film thickness distribution between each moving spray gun were found.

According to the present invention, a plurality of spray guns are installed at substantially equal intervals in the direction perpendicular to the traveling direction of the band-shaped plate glass in the vicinity of the moving high-temperature band-shaped plate glass. Is a method of forming a thin film on the surface of a glass sheet by spraying a chemical solution on the surface of the glass sheet while reciprocating synchronously so as to traverse the traveling direction of the glass. A method for forming a thin film on the surface of a plate glass, wherein the spray gun is reciprocated at an amplitude within ± 10% of the above to spray a chemical solution on the surface of the plate glass.

Further, according to the present invention, a plurality of spray guns are installed at substantially equal intervals in a direction perpendicular to the traveling direction of the strip-shaped glass sheet in close proximity to the moving hot strip-shaped glass sheet. A method of forming a thin film on a surface of a glass sheet by spraying a chemical solution on the surface of the glass sheet while reciprocating in a synchronous manner so as to cross the direction of movement of the glass sheet, and forming a thin film on the surface of the glass sheet. Of the thin film formed by spraying a chemical solution at room temperature, the diameter of the spray pattern in the width direction of the band-shaped plate glass generated on the surface of the plate glass by 2 times or more and 10 times or less. A thin film on the surface of a sheet glass characterized in that the film thickness distribution is thicker below the axes of two adjacent spray guns and becomes thinner continuously toward the center. It is a method.

Further, the present invention is characterized in that an exhaust port for exhausting a mist of mist sprayed by the spray gun is provided at the center of two adjacent spray guns. This is a method for forming a thin film.

Further, the present invention provides a spray gun, wherein an exhaust port is provided at the center of two adjacent spray guns for exhausting a mist of chemical liquid sprayed by the spray gun, and the exhaust port crosses a band-shaped plate glass. The method for forming a thin film on the surface of a sheet glass as described above, wherein the method reciprocates in synchronization with the reciprocating movement of the sheet.

Further, the present invention is characterized in that the speed at which the spray gun reciprocates across the band-shaped plate glass is constant except at both ends of the reciprocation, wherein the thin film is formed on the surface of the plate glass. Is the way.

Further, the present invention is characterized in that the moving speed when the spray gun reciprocates across the band-shaped glass sheet is twice to 20 times the moving speed of the band-shaped glass plate. This is a method for forming a thin film on the surface of a sheet glass.

Further, the present invention relates to a glass with a thin film produced by the above-mentioned method for forming a thin film on the surface of a sheet glass, wherein a difference in film thickness between a thick portion and a thin portion in a coating region between adjacent spray guns is provided. Is 1 of the average film thickness of the coating region.
It is a plate glass with a thin film characterized by being 0% or less.

The present inventors simulated the film thickness distribution of the thin film sprayed on the surface of the plate glass moving by the above calculation method and formed on the surface of the plate glass, and found that two spray guns were used. If the amplitude of the reciprocating motion of the spray gun is considerably smaller than the interval between the two spray guns, unevenness of the film thickness, which can be represented by a plurality of lines, which is a thick part with a zigzag thickness, occurs on the surface of the sheet glass. I found to do. Even when three or more spray guns are used, basically, the case of two spray guns is repeated.

That is, film thickness unevenness, which is equal to the number of spray guns and can be represented by a plurality of slightly zigzag lines that are thick portions, occurs on the surface of the sheet glass.

If the swing width of a plurality of spray guns is too large, the same film thickness unevenness as that caused when one spray gun is reciprocated is generated.

The present inventors synchronized the spray guns with substantially the same amplitude as the interval between the adjacent spray guns, and reciprocated so as to cross the traveling direction of the band-shaped plate glass.
When a chemical solution was sprayed on the surface of the glass sheet, the unevenness of the film thickness on the surface of the glass sheet between each moving spray gun,
It turns out that it can be minimized.

As shown in FIG. 3, the vertical axis is the film thickness, and the horizontal axis is the distance in the width direction of the band-shaped plate glass, and a chemical solution is sprayed by a fixed spray gun to thermally decompose the glass surface heated to 500 ° C. When the film thickness distribution of the thin film formed by the above method in the width direction of the plate glass is represented by a graph, the film thickness distribution of a single spray gun has a Gaussian distribution centering on point O on the spray axis of the spray gun.

As shown in FIG. 4, when two spray guns are set apart from each other by a distance L and a thin film is formed on the surface of a sheet glass heated in the same manner, two spray guns are formed as shown by hatching in the graph. Some parts overlap with the application area of the spray gun.

As a result, as shown in FIG. 5, the film thickness distribution in which a thick film portion M occurred on the surface of the plate glass at the center between the points O and O 'on the shooting axes immediately below the two spray guns. Become.

Even when the number of sprays is large, a spray pattern in which a thick portion M similarly occurs between the respective spray guns is obtained.

While maintaining the same interval between the spray guns, the film thickness distribution (basic pattern) shown in FIG. 5 is moved as shown in FIG. 6, and the chemical liquid is sprayed onto the glass substrate surface while moving the spray gun. The film thickness distribution obtained by the calculation was calculated.

As a result, it was found that a thin film having no film thickness unevenness was obtained on the surface of the sheet glass by reciprocating the spray gun synchronously with the same amplitude as the interval between the spray guns.

That is, when the basic pattern shown in FIG. 5 is moved, the spray gun is reciprocated synchronously with the same amplitude as the interval between the spray guns, so that the surface of the glass sheet is uniformly formed between the moving spray guns. A thin film having an appropriate thickness distribution can be obtained.

The preferable range of the swing width of the spray gun is preferably equal to the interval between adjacent spray guns, and it is necessary that at least the difference be within ± 10%. If it exceeds ± 10%, zigzag film thickness unevenness occurs.

For example, in the case of LOW-E glass (low-emission glass) with a non-light-coloring film produced by a thermal decomposition method, a tin oxide film is often used as a conductive film.

In the production of LOW-E glass, in order to form a uniform film without color unevenness, the reciprocating movement of the spray gun is performed with the spray gun having substantially the same amplitude as the spray gun interval. It is possible to minimize the increase in film thickness near the center between two adjacent spray guns, which is caused by overlapping of the application areas of the chemical solution on the surface of the plate glass. To obtain the desired performance of the LOW-E glass, a tin oxide film having a thickness of 300 nm to 500 nm is required.

Usually, when a plurality of spray guns are arranged in a straight line at rest, the coating regions overlap each other, as shown in FIG. 5, so that the film on the surface of the plate glass just below the central portion M of the adjacent spray guns is formed. The thickness increases.

The spray gun is reciprocated synchronously,
By setting the amplitude of the reciprocating motion of the spray gun within ± 10%, preferably the same as the interval between the adjacent spray guns, the surface of the sheet glass immediately below the central portion between two adjacent spray guns in the glass width direction can be obtained. It is possible to make the film inconspicuous as color unevenness without increasing the film thickness as much as possible.

However, in the basic pattern when the spray gun is stationary, if the thick portion M exists at the center of the adjacent spray gun, the film thickness becomes the smallest even if the condition for minimizing the film unevenness is examined. It is difficult to make the difference in film thickness between the thick and thin portions less than 5%. That is, the film thickness unevenness is not completely improved.

The amplitude of the reciprocating motion of the spray gun is
Even when the reciprocating speed of the spray gun is increased so that the interval between the adjacent spray guns is almost the same, and the coating is repeated, the film thickness unevenness is not completely improved.

In order to completely eliminate the color unevenness due to the film thickness unevenness, it is necessary to suppress the film thickness unevenness of the tin oxide film to 10 to 20 nm or less. In a situation where a thick portion M is formed at the center of two sprays adjacent to each other, a LOW-E glass with an achromatic film without completely uneven color cannot be produced.

The film thickness distribution (basic pattern) that can completely eliminate the film unevenness is obtained by a method in which the center of two adjacent spray guns sprays the chemical onto the plate glass surfaces of the two adjacent spray guns for spraying the chemical. FIG. 7 is a film thickness distribution (basic pattern) shown in FIG. 7 in which a thick portion is not formed at the center between two adjacent spray guns even if the application regions overlap.

When a chemical solution is applied with two spray guns, the basic pattern shown in FIG. 7 does not occur in the thin film thickness distribution on the surface of the plate glass where the thick portion does not occur at the portion where the application regions overlap. By making the amplitude of the reciprocating motion approximately equal to the interval between the adjacent spray guns and increasing the speed of the reciprocating motion of the spray gun and performing the overcoating, the film thickness unevenness is reduced to 1 at the central portion in the glass width direction. It becomes possible to make it within 2%.

The nozzles of commercially available spray guns usually indicate the effective coating area at room temperature as a specification in a manual or the like. Therefore, a preferable interval between the adjacent spray guns is represented by a multiple of the diameter of the effective application area of the spray gun at room temperature.

If the interval between the adjacent spray guns is set to be large, a portion having a large film thickness may be generated by applying a spray pattern, a spray discharge amount, a discharge pressure, and a pressure to an air spray gun or a chemical solution utilizing the Venturi effect. Depending on the airless spray or the chemical composition, etc., the distance between adjacent spray guns is at least twice as large as the diameter of the effective application area in the width direction of the plate glass of one spray gun at room temperature, preferably. Is required to be three times or more.

Compared with the effective application area at room temperature, the effective application area when applying the chemical solution to the surface of the high-temperature band-shaped plate glass with the spray gun is such that even when the same spray gun is used, the sprayed chemical solution has a high temperature. As a result, it evaporates before reaching the glass surface and expands, so that it becomes several times larger. Therefore, by setting the effective application area at room temperature to twice or more, preferably three times or more, the application areas overlap as shown in the graph of FIG. 4 in a high-temperature environment.

The number of spray guns should be reduced and the spray guns should be spaced apart so that the application areas do not overlap at all.
It is possible to apply the chemical solution to the surface of the glass sheet by increasing the swing width of the reciprocating motion of the spray gun and further increasing the moving speed of the spray gun. If the area exceeds 10 times, the movement of the spray gun is mechanically unreasonable, and conversely, film unevenness tends to occur.

The present inventors further studied and found that by providing an exhaust port formed of a duct or the like between each spray gun and exhausting the chemical mist floating in the air between each spray gun, By reducing the concentration of the chemical solution in the air between each spray gun and eliminating the thick portion M, the thick portion M between the two spray guns shown in the graph of FIG. It was found that a film thickness distribution in which no cracks occurred was obtained.

That is, a method of suppressing the occurrence of unevenness in film thickness between two adjacent spray guns is to heat the high-temperature plate glass at a portion where the film thickness on the surface of the plate glass becomes large when a chemical solution is sprayed. Is to forcibly exhaust the excess chemical mist that evaporates and floats in the space by providing an exhaust duct in the center of two adjacent spray guns.

Reciprocating the exhaust duct in synchronism with the reciprocating motion of the spray gun is more preferable because the film thickness on the surface of the glass sheet can be made more uniform.

The exhaust amount is the spray discharge amount, the spray pressure,
Depending on the reciprocating speed, air spray, airless spray, chemical composition, etc., the amount of exhaust from a pair of exhaust ducts provided at the center of two adjacent spray guns is the amount of chemical discharged from the spray gun. 100ml / min per, 4m ³ / min or more, 20 m ³ / min or less is preferred.

Discharge amount of chemical from spray gun 100m
When the displacement per 1 / min is less than 4 m ³ / min, the thickness of the coating on the surface of the plate glass is increased, and the film is evaporated and floated in the air by heating with the high temperature plate glass, which causes zigzag film thickness unevenness. , Cannot remove excess chemical mist.

The discharge amount of the chemical from the spray gun is 100 m
If the displacement per 1 / min is greater than 20 m ³ / min,
The application of air changes due to the airflow caused by the exhaust.

The exhaust volume of a set of exhaust ducts provided at the center of two adjacent spray guns is set to 4 m ³ / min or more per 100 ml / min of the chemical solution discharged from the spray gun.
0 m ³ / min or less, as shown in FIG.
A film thickness distribution is obtained in which a thick portion M does not occur between the spray guns.

In the thermal spraying method, a chemical solution obtained by dissolving an organic metal salt or an inorganic metal salt in an organic solvent is sprayed on the surface of a high-temperature plate glass, so that vapor of the organic solvent evaporated under a high-temperature environment is generated. It is necessary to quickly exhaust the organic solvent vapor for safety and to eliminate the influence on the film thickness of the organic solvent vapor.

For this purpose, it is preferable to provide a spray gun array and a hood covering the entire exhaust duct and exhaust the inside of the hood because the organic solvent vapor is exhausted efficiently and efficiently.

The moving speed of the spray gun when reciprocating across the band-shaped plate glass must be reduced at both ends of the reciprocating motion as long as the reciprocating motion is performed using mechanical means. Except for the part, the moving speed of the spray gun is preferably substantially constant.

If the speed is not constant, the residence time of the spray gun differs at the position of the spray gun, and the thickness of the thin film formed on the glass surface varies depending on the position of the spray gun. However, a thin film having a uniform thickness cannot be obtained even when the thickness is almost equal to the above.

The moving speed of the strip-shaped plate glass at the outlet of the float bath has a speed range determined by the glass conveying device, and the moving speed of the reciprocating motion of the spray gun cannot be increased without limit.

If the moving speed of the spray gun is too slow as compared with the moving speed of the band-shaped sheet glass, the thin film obtained on the surface of the sheet glass will have uneven thickness. Therefore, depending on the diameter of the effective application area of the spray in the traveling direction of the band-shaped glass sheet, the moving speed when the spray gun reciprocates across the band-shaped glass sheet is at least twice the moving speed of the band-shaped glass sheet. is necessary.

To eliminate unevenness in film thickness, the moving speed of the band-shaped plate glass may be reduced. However, if the moving speed of the band-shaped plate glass is too low, the temperature of the band-shaped plate glass decreases during the movement, and the At the surface temperature of the glass sheet that is suitable for thermally decomposing the glass by heating, the chemical cannot be sprayed, and the quality of the thin film formed on the glass sheet surface is degraded. Furthermore, if the moving speed of the band-shaped plate glass is low, the productivity is reduced and the cost of the plate glass is increased.

When the spray gun is allowed to stand still and sprayed, a spray film is formed so that a thick portion formed at the center of two adjacent spray guns due to the overlapping of the spray areas of the adjacent spray guns cannot be formed. Is reciprocated at substantially the same amplitude as the interval between the spray guns, the reciprocating speed of the spray gun is increased, and the uniformity of the film thickness at the central portion of the adjacent sprays is increased if the spray is applied repeatedly. Even if the moving speed of the spray gun is increased more than 20 times, the uniformity of the thickness of the thin film formed on the surface of the glass sheet does not change anymore. The moving speed when the spray gun reciprocates across the band-shaped glass sheet is 20 times or less the moving speed of the band-shaped glass sheet.

The spray pattern when a chemical is applied by a spray gun has various patterns such as a convex lens shape, a hollow circular shape and a circular shape, and can be appropriately selected according to the type of the chemical solution or a desired film thickness. is there. The effective application area of the spray at room temperature varies depending on the number of the spray gun, the liquid pressure, the air pressure in the case of air spraying, the viscosity of the chemical solution, and the like. Usually, the diameter in the width direction of the sheet glass is 10 cm.
Above, it is 50 cm or less.

The number of spray guns must be such that the amount of chemical solution discharged from each spray gun must be equal.
Considering the ease of maintenance of the spray gun, etc., the smaller the better, the more it is necessary to eliminate the unevenness of the thin film formed on the surface of the sheet glass. If the discharge amount of the chemical liquid from one spray gun is too large, the characteristics of the thin film deteriorate and the number of film defects increases.

In a glass manufacturing apparatus using the float method, since the glass width of the band-shaped plate glass is rarely more than 5 m, the number of spray guns for spraying the chemical is two.
0 or less is preferable. More than 20 means that if the number of spray guns is too large, if the spray guns are brought close to each other, the interaction between the spray guns will result in a high concentration of the chemical solution sprayed between two adjacent spray guns. There is a problem that a portion is generated or film unevenness occurs due to turbulence of an air flow above the glass sheet.

When the spray pattern of the chemical solution sprayed from the spray gun is an elongated rectangle, that is, a convex lens shape, the long axis of the convex lens may or may not be parallel to the glass width direction.

According to the method for forming a thin film on the surface of a glass sheet of the present invention, a thick portion of the thin film between the spray guns formed by applying a chemical by each spray gun and reciprocating so as to cross the traveling direction of the band-shaped glass sheet. And the difference in film thickness between the thinner portions and the thinner portions is 10% or less of the average film thickness in the coating range.

In the thermal spray method, when the moving speed of the spray gun is increased, the number of coatings increases and a uniform film can be obtained. However, even when the number of spray guns is small and the moving speed of the spray gun is low, By using the spray conditions including the swing width of the spray gun of the present invention, a uniform film can be obtained on the surface of the glass sheet between the spray guns.

In the present invention, the intervals between the spray guns may not be exactly the same, and may be slightly shifted as long as they are within ± 10%.

In the present invention, it is preferable that the supply amounts of the chemicals discharged from the respective spray guns are even.

Not only when a thin film is formed on the surface of a high-temperature band-shaped plate glass at the outlet of the float bath by the float method, but also
Redraw method, downdraw method, fusion method, and the like, even in a method of manufacturing a sheet glass other than the float method, if a spray gun is provided near a high-temperature sheet glass, the method of forming a thin film on the sheet glass surface by the heat spray method of the present invention. Since the method can be used, the method of the present invention can be applied to other than the float method.

The method of forming a thin film according to the present invention is not limited to the case of using a flat glass, but is applicable to a case where a uniform thin film is mechanically and continuously applied to a smooth surface of a substrate, for example, a smooth surface made of metal, plastic or the like. Is also applicable. In this case, the substrate to be applied may be at a high temperature or a low temperature, and the temperature of the substrate does not matter as long as it can be sprayed.

[0087]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus for forming a thin film by a thermal spray method used in an embodiment of the present invention will be described.

FIG. 1 is a schematic plan view of an apparatus for forming a thin film on a surface of a sheet glass by a thermal spray method, which is used in an embodiment of the present invention.

FIG. 2 is a schematic side view of the thin film forming apparatus of FIG. 1 as viewed from the flow direction of the sheet glass.

The thermal spraying method is a method in which a spray bath is installed at a distance L2 above the band-shaped glass sheet 2 on the surface of the hot band-shaped glass sheet 2 moving on the roller 3 at the outlet of the float bath, as shown in FIG. This is a method in which a chemical is sprayed on the application area by the spray gun 1 with the gun 1, the chemical is decomposed by the temperature of the band-shaped plate glass 2, and a functional thin film is formed on the surface thereof. A thin film is formed on the surface of the band-shaped plate glass 2 by reciprocating the adjacent spray guns 1 separated by the distance L1 in the width direction.

The present invention is a method for producing a thin glass sheet with a thin film by a thermal spray method so as not to cause unevenness in film thickness in a coating region between adjacent spray guns.

In order to prevent film unevenness, under the spray conditions of the present invention, a thin film is formed on the surface of the sheet glass, and an exhaust port such as a duct 4 for disposing excess chemical mist shown in FIGS. 1 and 2 is disposed. Installation is preferred. As shown in FIG. 2, in order to increase the disposal efficiency of the excess chemical mist, it is preferable to provide the exhaust port close to a portion where the concentration of the chemical mist in the air increases.

The apparatus for forming a thin film by the thermal spray method which can be used in the present invention is not limited to the apparatus used in the embodiments, but
It is possible to use a similar device with more spray guns than in the examples.

[0094]

EXAMPLE 1 Width, moving at a speed of 8 cm / sec at the float bath outlet
Above the band-shaped plate glass 2 having a thickness of 120 cm and a thickness of 3 mm, the airless spray gun 1 is arranged in the width direction of the band-shaped plate glass 2 at an interval L1 of 40 cm, and the distance L2 between the band-shaped plate glass 2 and the spray gun 1 is set at 30 cm. Two spray guns were installed and the spray gun 1 was reciprocated. That is, the spray gun 1 is synchronously moved at a speed of 25 cm / sec except for both ends of the reciprocating motion, and is reciprocated in the glass width direction at an amplitude of 40 cm and at the same interval L1 between adjacent spray guns. Was. The ratio of the moving speed of the band-shaped plate glass 2 to the moving speed of the reciprocating motion of the spray gun 1 is 1: 3.1.

Further, an exhaust duct 4 is provided at the center of two adjacent spray guns 1 and is sprayed and heated by a high-temperature plate glass in a region where the concentration of the chemical solution sprayed from the spray guns 1 in the air is high. Then, while forcibly exhausting the chemical mist that evaporates and floats in the air, the chemical for tin oxide film formation is discharged at a pressure of 35 kg with the chemical composition shown in Table 1.
/ Cm ² and sprayed from each spray gun 1 to form a tin oxide film on the surface of the glass sheet.

When the chemical was sprayed while the spray gun 1 was stopped, the film thickness distribution of the thin film formed on the surface of the plate glass was measured.
The thicker portion due to the overlap of the sprayed areas at the center of the sample was not measured.

When the spray gun 1 is reciprocated under the above conditions, the film thickness unevenness of the thin film formed on the surface of the band-shaped plate glass 2 at the center in the glass width direction and at a width of 42 cm is as follows.
20 nm. The average film thickness in the glass width direction at a width of 42 cm was 490 nm, and no zigzag streak-like unevenness was visually observed. The film thickness was measured with an ellipsometer. Hereinafter, also in Examples 1 to 4 and Comparative Examples 1 and 2, the film thickness was measured with an ellipsometer. Example 2 Moving at a speed of 8 cm / sec at the float bath outlet, width,
An airless spray gun 1 having a spacing of 40 cm in the width direction of the band-shaped plate glass 2 above the band-shaped plate glass 2 having a thickness of 120 cm and a thickness of 3 mm, and a band-shaped plate glass 2 and a spray gun 1
Was set to 42.5 cm, and two spray guns were installed, and the spray gun 1 was reciprocated. That is, spray gun 1
Was moved synchronously at a speed of 50 cm / sec except for both ends of the reciprocating motion, and was reciprocated in the glass width direction at an amplitude of 42.5 cm at the same interval between the adjacent spray guns 1. Moving speed of strip-shaped plate glass 2 and spray gun 1
The ratio of the moving speeds of the reciprocating motions is 1: 6.2.

Further, an exhaust duct 4 is provided at the center of two adjacent spray guns 1 and is sprayed and heated by a high-temperature plate glass in a region where the concentration of the chemical solution sprayed from the spray guns 1 in the air is high. Then, while forcibly exhausting the chemical mist that evaporates and floats in the air, the chemical for the tin oxide film having the chemical composition shown in Table 1 was subjected to a chemical pressure of 35 kg / cm.
^{In step 2} , spraying was performed from each spray gun 1 to form a tin oxide film.

When the spray gun 1 was stopped and a chemical solution was sprayed, the film thickness distribution of the thin film formed on the surface of the plate glass was measured. As a result, the areas sprayed at the center of two adjacent spray guns 1 overlap. As a result, there was no thick portion.

When the spray gun 1 is reciprocated under the above conditions, the film thickness unevenness of the thin film formed on the surface of the band-shaped plate glass 2 at the center in the glass width direction and at a width of 40 cm is 1
It was 0 nm. The average film thickness in the glass width direction at a width of 40 cm was 495 nm, and no zigzag streak-like unevenness was visually observed. Example 3 Moving at a speed of 8 cm / sec at the float bath outlet, width,
The air spray gun 1 is placed above the band-shaped glass sheet 2 having a thickness of 120 cm and a thickness of 3 mm in the width direction of the band-shaped glass sheet 2.
Were set at an interval of 40 cm and the distance between the band-shaped plate glass 2 and the spray gun 1 was set to 30 cm, and two spray guns were installed, and the spray gun 1 was reciprocated. That is, the spray gun 1 is synchronously moved at a speed of 50 cm / sec except for both ends of the reciprocating motion, and is reciprocated in the glass width direction at an amplitude of 40 cm and equal to the interval L1 between adjacent spray guns. Was. The ratio of the moving speed of the band-shaped plate glass 2 to the moving speed of the reciprocating motion of the spray gun 1 is 1: 6.2.

An exhaust duct 4 is provided at the center of two adjacent spray guns 1, and is heated by the sprayed and high-temperature plate glass 2 in the region where the concentration of the chemical solution sprayed from the spray guns 1 in the air is high. And evaporate,
While forcibly exhausting the chemical mist floating in the air, the tin oxide film forming chemical with the chemical composition shown in Table 1 was discharged at a pressure of 35k.
g / cm ² at each spray gun 1
A tin oxide film was formed on the surface of the glass sheet.

When the spray gun 1 was stopped and the chemical was sprayed, the film thickness distribution of the thin film formed on the surface of the plate glass was measured. No thick part was measured.

When the spray gun 1 is reciprocated under the above conditions, the film thickness unevenness of the thin film formed on the surface of the band-shaped plate glass 2 at the center in the glass width direction and at a width of 40 cm is as follows.
It was 10 nm. The average film thickness at a width of 40 cm in the glass width direction was 495 nm, and no zigzag streak-like unevenness was visually observed. Example 4 Moving at a speed of 8 cm / sec at the float bath outlet, width,
The airless spray gun 1 is placed above the band-shaped plate glass 2 having a thickness of 120 cm and a thickness of 3 mm in the width direction of the band-shaped plate glass.
Were set at an interval of 40 cm and the distance between the band-shaped plate glass 2 and the spray gun 1 was set to 30 cm, and two spray guns were installed, and the spray gun 1 was reciprocated. That is, the spray gun 1 is synchronously moved at a speed of 50 cm / sec except for both ends of the reciprocating motion, and has an amplitude of 40 cm, slightly narrower than the interval between the adjacent spray guns 1, and reciprocates in the glass width direction. Exercise. The ratio of the moving speed of the band-shaped plate glass 2 to the moving speed of the reciprocating motion of the spray gun 1 is 1: 6.2.

Further, an exhaust hood is provided in the entire spray zone, and the high-temperature sheet glass 2 is provided in the entire spray zone.
With the chemical composition shown in Table 1, a tin oxide film chemical was sprayed at a chemical pressure of 35 kg / cm ² from each spray gun 1 while forcibly exhausting the chemical mist that was heated and evaporated and drifted in the air. By spraying, a tin oxide film was formed.

When the chemical was sprayed with the spray gun 1 stopped, the film thickness distribution of the thin film formed on the surface of the glass sheet was measured. And the portion with a large film thickness was measured.

When the spray gun 1 is reciprocated under the above conditions, the thickness unevenness of the thin film formed on the surface of the band-shaped plate glass 2 at the center in the glass width direction and at a width of 45 cm is as follows.
18 nm. The average film thickness in the glass width direction at a width of 45 cm was 480 nm, and no zigzag streak-like unevenness was visually observed. Comparative Example 1 Moving at a speed of 8 cm / sec at the float bath outlet, width,
Two airless spray guns are installed above the band-shaped plate glass 2 having a thickness of 3 mm and 120 cm in width direction of the band-shaped plate glass at a spacing of 40 cm and a distance between the band-shaped plate glass 2 and the spray gun 1 of 30 cm. The spray gun was reciprocated. That is, the spray gun 1 is synchronously moved at a speed of 25 cm / sec except for both ends of the reciprocating motion, and is reciprocated in the glass width direction with an amplitude of 30 cm, 10 cm narrower than the interval between adjacent spray guns. Was.
The ratio of the moving speed of the band-shaped plate glass 2 to the moving speed of the reciprocating motion of the spray gun 1 is 1: 3.1.

Further, an exhaust hood is provided in the entire spray zone. In the entire spray zone, the chemical mist heated by the high-temperature sheet glass and evaporated and floated in the air is forcibly exhausted. A tin oxide film chemical was sprayed from each spray gun 1 at a chemical pressure of 35 kg / cm 2 to form a tin oxide film.

When the spray gun 1 was stopped and a chemical solution was sprayed, the film thickness distribution of the thin film formed on the surface of the plate glass was measured. , A thick part was measured.

When the chemical was sprayed on the surface of the glass sheet while the spray gun 1 was reciprocated under the above conditions, zigzag streaky unevenness was visually observed on the surface of the glass sheet 2. The thickness unevenness of the thin film formed on the surface at a width of 55 cm at the center in the glass width direction was 70 nm. The thickness of the streak portion is 520 n
m, and the average film thickness in the other 55 cm width was 465 nm. Comparative Example 2 Moving at a speed of 8 cm / sec at the float bath outlet, width,
The airless spray gun 1 is placed above the strip-shaped glass sheet 2 having a thickness of 120 cm and a thickness of 3 mm in the width direction of the strip-shaped glass sheet 2 at intervals of 40 cm, and the distance between the glass and the spray gun is set at 30 cm. Gun 1 was reciprocated. That is, the spray gun is moved synchronously at a speed of 25 cm / sec except for both ends of the reciprocating motion, and the amplitude,
67.5cm, 2mm from the interval between adjacent spray guns 1
The sheet was widened by 7.5 cm and reciprocated in the glass width direction.
The ratio of the moving speed of the band-shaped plate glass 2 to the moving speed of the reciprocating motion of the spray gun 1 is 1: 3.1.

Further, an exhaust hood is provided in the entire spray zone, and sprayed in the entire spray zone.
The tin oxide film chemical is sprayed at a chemical liquid pressure of 35 kg / cm 2 with the chemical composition shown in Table 1 while forcibly exhausting the chemical mist that is heated and evaporated by the high-temperature plate glass 2 and floats in the air. It was sprayed from Gun 1 to form a tin oxide film.

When the spray liquid was sprayed while the spray gun 1 was stopped, the film thickness distribution of the thin film formed on the surface of the glass sheet was measured. And the portion with a large film thickness was measured.

When the spray gun 1 was reciprocated under the above conditions and a chemical was applied to the surface of the plate glass, zigzag streak-like unevenness was visually observed on the surface of the plate glass 2. The thickness unevenness of the thin film formed on the surface at the center in the glass width direction and at a width of 50 cm is 8
It was 0 nm. The film thickness of the streak-like portion was 530 nm, and the average film thickness in the other 50 cm width was 460 nm.

[0113]

[Table 1]

[0114]

According to the method for forming a thin film on the surface of a sheet glass of the present invention, a sheet glass with a thin film having a uniform thickness and excellent appearance can be produced by a thermal spray method using a plurality of spray guns.

That is, the chemical is applied to the surface of the high-temperature plate glass under the conditions of the method for forming a thin film on the surface of the plate glass of the present invention, ie, the interval between the adjacent spray guns, the number of spray guns, the moving speed of the reciprocating motion, and the spray conditions. In addition, by providing an exhaust duct in the center of the adjacent spray gun and removing excess chemical mist, a thin film of uniform thickness and excellent appearance can be efficiently applied between the spray guns on the surface of the glass sheet. Can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of an apparatus for forming a thin film on a surface of a sheet glass by a thermal spray method used in an embodiment of the present invention.

FIG. 2 is a schematic side view of an apparatus for forming a thin film on a surface of a sheet glass by a thermal spray method used in an embodiment of the present invention.

FIG. 3 is a graph of a film thickness distribution in a sheet glass width direction when a chemical solution is applied by one spray gun.

FIG. 4 is a graph showing overlap when a chemical solution is applied by two spray guns.

FIG. 5 is a graph of a film thickness distribution in a sheet glass width direction when a chemical solution is applied by two spray guns.

FIG. 6 is an explanatory diagram for simulating a film thickness distribution when a spray gun is moved.

FIG. 7 is a graph of a film thickness distribution when an excessive chemical mist at the center of two spray guns is removed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spray gun 2 Strip-shaped plate glass 3 Transport roller 4 Exhaust duct

Continued on the front page (72) Inventor Hatakenaka, 2805 Imafukunakadai, Kawagoe-shi, Saitama F-term in the Chemical Research Laboratory, Central Glass Co., Ltd.F-term (reference) AA01 AA11 AB14 AB17 AB19 AC04 AC05 AC06 AC08

Claims (7)

[Claims] 1. A plurality of spray guns are installed at substantially equal intervals in a direction perpendicular to the traveling direction of a band-shaped plate glass in the vicinity of a moving high-temperature band-shaped plate glass.
A method for forming a thin film on a surface of a glass sheet by spraying a chemical solution on the surface of the glass sheet while reciprocating in a synchronized manner so as to cross the traveling direction of the belt-shaped glass sheet. A method for forming a thin film on a surface of a glass sheet, wherein the spray gun is reciprocated with an amplitude of ± 10% of the interval between the guns to spray a chemical solution on the glass sheet surface. 2. A plurality of spray guns are installed at substantially equal intervals in a direction perpendicular to the traveling direction of the band-shaped plate glass in proximity to the moving high-temperature band-shaped plate glass.
A method for forming a thin film on a surface of a glass sheet by spraying a chemical solution on the surface of the glass sheet while reciprocating in a synchronized manner so as to cross the traveling direction of the belt-shaped glass sheet. A thin film formed by stopping the spray gun at intervals of two to ten times the diameter of the spray pattern in the width direction of the band-shaped plate glass generated on the surface of the plate glass by spraying a chemical solution at room temperature. Characterized in that the film thickness distribution is thicker beneath the axes of two adjacent spray guns and continuously thinner toward the center. 3. An exhaust port for exhausting a mist of mist sprayed by a spray gun is provided at the center of two adjacent spray guns. A method for forming a thin film on the surface of a glass sheet. 4. An exhaust port for exhausting atomized chemical mist sprayed by the spray gun is provided at the center between two adjacent spray guns, and the exhaust port reciprocates the spray gun across a band-shaped plate glass. 3. The method for forming a thin film on a surface of a sheet glass according to claim 1, wherein the reciprocating movement is performed synchronously. 5. The sheet glass surface according to claim 1, wherein a speed at which the spray gun reciprocates across the band-shaped sheet glass is constant except at both ends of the reciprocation. Method of forming a thin film. 6. The moving speed of the spray gun when the spray gun reciprocates across the band-shaped glass sheet is at least twice and at most 20 times the moving speed of the band-shaped glass sheet. Item 6. The method for forming a thin film on a surface of a sheet glass according to Item 5. 7. A glass with a thin film produced by the method for forming a thin film on a surface of a sheet glass according to claim 1, wherein the thin film has a thick portion and a thin portion in a coating region between spray guns. The thickness difference is 10% of the average film thickness of the coating area.
A sheet glass with a thin film, characterized in that: