JPH0346414B2 - - Google Patents

Description

Claim 1: A method for developing a film on the surface of a glass plate at a temperature in the range of 510 to 625°C, comprising: a plurality of particles, each particle being substantially formed of a thermally decomposable organometallic salt of at least two metals; A method as described above, comprising the step of contacting the surface of a heated glass plate with a spray powder composition consisting of hollow, generally spherical particles.

2. The method of claim 1, wherein said plurality of hollow, generally spherical particles are comprised of substantially the same proportions of metal composition, such that each of said particles is substantially homogeneous.

3. The method of claim 1 or 2, wherein the average spherical particle size is about 6μ.

4. A method of developing a film on the surface of a glass plate at a temperature in the range of 510 to 625°C, the method comprising forming a plurality of hollow particles, each particle being substantially formed of a pyrolyzable organometallic salt of cobalt, iron, and chromium. 2. The method of claim 1, further comprising the step of contacting the surface of a heated glass plate with a powder spray composition comprising generally spherical particles.

5. The method of claim 4, wherein said plurality of hollow, generally spherical particles are comprised of approximately the same proportions of metal composition, such that each of said particles is generally homogeneous.

6. The method of claim 5, wherein the metal composition of the particles is approximately 70% cobalt, 19% iron, and 11% chromium by weight.

7. The method of claim 5 or claim 6, wherein the average spherical particle size is about 6μ.

TECHNICAL FIELD The present invention relates to a method of developing a coating on the surface of a glass plate at a temperature within the range of 510<0>C to 625<0>C. Specifically, this method was developed to apply such a coating onto a glass sheet as it is being moved in a selected direction from the glass manufacturing process. The method of the present invention comprises a powder spray composition comprising a plurality of hollow, generally spherical particles formed of pyrolyzable organometallic salts of at least two metals;
This method involves bringing the glass plate into contact with the surface of the heated glass plate. In order to change the light transmission characteristics of the glass plate,
A coating is applied onto the glass plate.

BACKGROUND ART AND PRIOR ART The history of pyrolytic coating of powder coatings on the surfaces of glass plates is described below.

U.S. Patent No. 3,081,200, column 3, line 13, states:
It is disclosed that both solutions and powders were sprayed to form a pyrolyzable metal oxide coating on a heated glass plate. However, the examples in that patent relate to the use of solutions of coating materials, and how to successfully coat a powder to form a pyrolyzable metal oxide film on a glass plate. There is no explanation as to whether it will be done. The patent also does not teach how to prepare a powder that can be coated onto a glass plate to form a pyrolyzable film thereon.

German patent nos. 2529076, 2529077 and no.
No. 2529079 is concerned with the development of metal oxide films on glass plates.

In the above German Patent No. 2529076, 500~
The metal salt particles are electrically charged before being coated on a glass plate that has been preheated to a temperature within the range of 650°C. The patent discloses that thermally decomposable organometallic salts can be used and that a preheated carrier gas can be used to transport the particles to the glass plate.
The patent states that the charging and distribution of particles should be effected downwardly at an angle of 90° toward the glass plate from a gas distributor extending transversely to the direction of travel of the glass plate passing below. teaching.

German Patent No. 2,529,077 discloses a method for forming a metal oxide film on a glass plate by a pyrolytic method. The starting material is a powdered metal compound which is conveyed by an inert carrier gas into a cyclone in which the smallest particles of the compound are separated from the coarser particles and then conveyed with the carrier gas stream to the surface of the glass plate to be coated. It will be done. The coarse particles are collected and partially evaporated by heating under an inert atmosphere. Thereafter, the vapor of the metal compound obtained is mixed with a carrier gas which carries the fine particles to the surface to be coated. Accordingly, the patent teaches simultaneously coating a glass surface with both a relatively fine, thermally decomposable organic metal salt and a metal vapor of the same type to develop a metal oxide film on the surface. It is something to do.

German Patent No. 2,529,079 discloses a method in which relatively large particles of a pyrolyzable material are dropped onto a glass plate and a coating is developed on the plate.

US Pat. No. 3,852,098 discloses a method of applying a metal-containing coating to a glass plate by heating the glass and contacting the hot glass with a gas mixture. The patent is not concerned with applying a powdered material directly to the surface of the glass to develop a metal oxide coating on the surface. Rather, the disclosed method uses a gas mixture containing 40-100% by volume of reactive metal compound vapor as the coating medium. The glass heats the mixture to a suitable temperature which causes the metal vapor compounds to react and deposit a film.

US Pat. No. 4,182,783 is a patent for a vapor deposition method for producing metal oxide films on glass plates. The method first establishes a fluidized bed of dispersed particulate solid coating reactants and then introduces a volume of fluidized gas and suspended particulate solid coating reactants into an evaporator. After mixing an additional volume of gas therewith, all particulate solid coating reactants are vaporized in the reactant/gas mixture. This reactant/gas mixture is then contacted with the thermal substrate to be coated to deposit a coating thereon.

US Pat. No. 4,188,199 discloses a method for forming a metal compound coating on the surface of a continuously longitudinally moving glass ribbon. Metal compounds are formed on the surface of the moving glass ribbon by contacting the ribbon surface, which is maintained at an elevated temperature, with a flowing medium containing a substance that undergoes a chemical reaction or decomposition.

US Pat. No. 4,230,271 discloses an apparatus for depositing particulate matter suspended in a gas evenly and uniformly on at least one side of a glass plate. Specifically, the glass plate is a glass strip and the product placed thereon can be a metal salt.

The gist of the method of the invention is to provide a method for developing a film on the surface of a glass plate heated to a temperature in the range of 510-625°C. The method is characterized by contacting the surface of a heated glass plate with a specified thermally decomposable powder spray composition.

DISCLOSURE OF THE INVENTION The present invention relates to a method of developing a coating on the surface of a glass plate. More particularly, the present invention relates to a method of developing a film for coating a glass plate that has been heated to a temperature within the range of 510-625°C. Therefore, a coating is developed on the surface of the glass plate by the pyrolytic coating method.

In accordance with the teachings of the present invention, a powder spray composition comprising a plurality of hollow, generally spherical particles formed of pyrolyzable organometallic salts of at least two metals and a heated glass plate are prepared. contact with the surface.

In accordance with the further teachings of the present invention, the generally spherical particles are homogeneous because they are comprised of approximately the same proportions of metal composition. According to a more detailed teaching of the method of the invention, the average particle size of the spherical particles is about 6μ.

In accordance with a preferred embodiment of the invention, a powder spray composition comprising a plurality of hollow, generally spherical particles formed of pyrolyzable organometallic salts of cobalt, iron and chromium; and a heated glass plate. contact with the surface of

In further detailing a preferred embodiment of the invention, the generally spherical particles are composed of approximately the same proportions of metal composition, so that they are homogeneous. The preferred ratio is approximately 70% cobalt and 19%
of iron and 11% of chromium. Again, the preferred particle size of this preferred composition is approximately
It is 6μ.

[Brief explanation of drawings]

The novel features that appear to characterize the present invention are:
The details are set forth in the appended claims. However, the construction and operation of the invention, as well as additional objects and advantages thereof, will become apparent from the following description of specific embodiments, taken in conjunction with the drawings. The same reference symbols in the drawings indicate the same parts throughout the drawings.

FIG. 1 is a schematic front view of an apparatus capable of carrying out the method of the invention, and FIG. 2 is a plan view of the apparatus shown in FIG.

BEST MODE AND INDUSTRIAL APPLICATION The following description is a description of what is believed to be a preferred embodiment of the invention for developing a coating on the surface of a glass plate. The following description is also a description of what is currently believed to be the best mode of carrying out the invention. This description is not intended to limit the broad scope of the invention. Although preferred materials have been used to illustrate the invention as required by patent law, the method of the invention cannot be operated only using the materials described and other materials may be substituted. It means that you can. Furthermore, the method of the present invention can also be effectively utilized with substances that will be developed in the art in the future, such as newly developed thermally decomposable metal salts. Therefore, regardless of the specific material used in the method,
Since the gist of the present invention remains unchanged, the method disclosed herein is intended to be effectively utilized even with substances that will be developed in the future.

``Method of Placing a Metal Oxide Film on the Surface of a Heated Glass Substrate'' (METHOD OF PLACING A), filed on November 30, 1981
METALLIC OXIDE FILM ON A
SURFACE OF A HEATED GLASS
U.S. Patent Application No. 325891 entitled SUBSTRATE
The method of the present invention will be explained by the spray method described in the specification. The above-mentioned application discloses a method of coating the surface of a heated glass plate with organic metal powder. This method of coating powder particles can also be used to coat hollow, generally spherical particles used in the method of the invention.

In the following, a preferred method for producing a granular spray composition having a preferred composition will be disclosed. The composition consists of a plurality of hollow, generally spherical particles, each particle formed of a pyrolizable organometallic salt of at least two metals. A preferred processing method is spray drying. This particular method begins by mixing together a powder mixture consisting of approximately 70% by weight cobalt acetylacetonate, 18% by weight ferric acetylacetonate, and 12% by weight dichromic acetylacetonate. Mix 19% by weight of the mixed powder and 81% by weight of technical grade methylene chloride to form a solution.

Spray drying the solution to obtain cobalt,
A plurality of hollow, generally spherical particles are formed of a pyrolizable organometallic salt of a preferred composition of iron and chromium. According to one spray drying method, Bowen Engineering
An open cycle spray dryer manufactured by M. Engineering, Inc. was supplied with 19.1 pounds per minute of the solution to be spray dried. The spray dryer was indirectly heated with steam and equipped with a centrifugal atomizer. Air inlet temperature is 100
°C, and the air outlet temperature was 58-61 °C. The atomizer speed was set to 21000 rpm.

The powder spray composition produced by this process consisted of a plurality of hollow, generally spherical particles. Each of these particles was formed of pyrogenic organometallic salts of cobalt, iron, and chromium in approximately the same proportions for each particle. The preferred raw material ratios in each particle under the above conditions were approximately 70% cobalt, 19% iron, and 11% chromium. Although each of the particles generally contains the raw material in the above proportions, thus characterizing the sprayed material as generally very homogeneous, during any physical processing step some particles may Of course, it is easy to understand that there are cases in which sex cannot be obtained. This is evidenced by the high bulk of the spray composition. In this specification, when we say very homogeneous,
That means that at least 85-90% of the particles are likely to have approximately the same metal composition within standard statistical ratios.

One of the other characteristics of this powder is its shape factor.
factor). This factor is a measure of sphericity, with a perfect sphere (a circle in two dimensions) having the highest shape factor of 1. Analysis is performed by an image analyzer. The shape factors for the powders produced as above are: Shape factor distribution percentage 0.9-1.0 71.2 0.8-0.9 12.3 0.7-0.8 5.6 0.6-0.7 3.9 0.0-0.6 7.0 Spray composition produced as above Another way to characterize something is particle size distribution. In a preferred composition, the particle size distribution is one with an average particle size of 6μ. The particle size distribution is shown below: size range, μ distribution percentage <2 10.2 2-4 32.7 4-6 23.3 6-8 12.1 8-10 7.2 10-12 4.1 12-14 3.0 14-16 1.8 >16 5.6 Preferred powder Although a preferred method of producing the spray composition is described above, a preferred method of applying the spray composition to a glass plate is described below. Specific application methods are described in U.S. patent application no.
According to the method described in the specification of No. 325891.

The powder spray composition produced as described above is stored in a powder composition supply device 12 as a source of dry powder spray composition 10. Dry powder 10 is entrained into a gas stream, such as an air stream, by methods well known in the art and then passed through supply tube 14.
move through. In this way, supply pipe 1
4, the dry powder 10 is fed to a position above the glass plate 16. The glass plate is moved by movable rollers 18 to 18 to move in the direction of the arrow in FIG.
18.

The glass plate is placed in a float chamber 20 in which the thin plate is manufactured.
and moves through an annealing reactor 22 where the glass is cooled and annealed in a well known manner. The method of the invention in this preferred embodiment is accomplished at a location between the float chamber and the annealing reactor. At this location, the glass plate has a temperature ranging from 370°C (700°) to 650°C (1200°). This temperature range is high enough to vaporize organic powder spray compositions, so that such vapor-forming metals
A metal oxide film is formed on the glass plate 16 by reacting with oxygen contained in the surrounding environment of the glass plate or with oxygen within the glass plate itself.

Spray nozzles 24 are arranged at spaced locations above the surface of the glass plate 16. This spray nozzle has a spray nozzle reciprocating device 26.
attached to the device, by means of which the spray nozzle is moved back and forth across the width of the glass pane passing beneath it. The spray nozzle is placed at an angle of 30° to 45° to the glass plate passing beneath it, and the distance of the nozzle, measured in vertical distance from the nozzle gun to the glass, is 22.8 to 30.5 cm (9 to 12 inches). . When a specific composition is used, the composition of the coating applied to the glass substrate is approximately 66-69% cobalt and 7% chromium.
~9.2% and iron 22.5-25.5%.

The chemical and physical durability of this coating composition is
It can be measured in two separate tests. Chemical durability is measured in a first method by subjecting the coated sample to a 5 hour hydrochloric acid vapor test. In this case,
An attempt was made to surround the material with hydrochloric acid vapor and attack the coating on the glass plate. Attacking the coating changes the level of solar energy that passes through the glass. When the membrane's durability is attacked, a large amount of energy is transmitted through it. The coated glass was considered acceptable if the change in energy transmission was less than 15% and unacceptable if the change was more than 15%. The change for this coating composition was less than 1%, which was very good.

The second test is a physical durability test. In this test, the sample is first thermally tempered.
Thereafter, the tempered test samples are subjected to a humidity test, in which case they are exposed to 100% humidity for 6 weeks at 49°C (120°C). This high humidity causes the coating on the surface to loosen its adhesion to the surface and cause it to fall off. The measure of durability is
The surface coating should remain in place for a long time and not more than 1% of the coating should fall off the surface. If more falls out, the sample is rejected as a failure. The change for the above coating composition was again less than 1%.

Spray nozzle 24 is designed so that additional air is added to the spray composition conveyed within supply tube 14 . The purpose of adding air is
This is to accelerate the spray powder from a gun located at a position spaced above the moving glass plate 16. Acceleration is achieved by entraining the spray composition in a high-velocity air stream, with individual particles traveling between 6 meters per second (20 feet per second) and 36 feet per second.
m (120 feet per second) and the spray powder is separated into individual particles. Acceleration is transvector
This is achieved by a commercially available device called . This device has the ability to amplify the air ejected from the transvector nozzle to 20 times the volume of the intake air.

A fan-shaped spray 28 is thereby established for the spray composition. As the entrained spray composition is accelerated to produce a fan spray as described above, two things can happen to the individual spherical particles of the spray powder. The first thing that can happen is that these particles are rapidly transported to a location parallel to the surface of the glass sheet 16, where vaporization and decomposition of these individual particles takes place and they react with oxygen to form the glass sheet. forming a tightly adherent coating over the The second thing that can happen to these particles is that they fail to vaporize, decompose, or react within the acceptable residence time necessary to form a tightly adherent coating on the moving glass substrate. Particles, if any, should be expelled immediately from points parallel to the surface of the glass plate. An exhaust hood 30, shown only in FIG. 1, is used to exhaust the waste spray powder from the surface of the glass plate.

A heterogeneous dry powder mixture is sprayed by using a spray composition consisting of a plurality of hollow, generally spherical particles, each particle formed of a pyrolyzable organometallic salt of at least two metals. It has been found that an improved coating is produced on the surface of the glass plate than that obtained by the method of the present invention. One avenue that has been found to be an improvement is in the area commonly known in the art as "mottle." Mottling refers to small, localized differences in the transmission properties of a glass plate.

Although mottling is a subjective measurement, we attempted to minimize the subjectivity of this measurement as much as possible by having only one person evaluate all of the produced samples. Good mottling is given a score of 1, and bad mottling is given a score of 7. A mottled score of 7 means that many locally different transmittances are observed over the entire surface of the glass. In layman's terms, it's like leaving a glass pane out in a rainstorm and dirt builds up on the glass surface. If you take a close look at this glass plate, you will notice differences in transmission due to dirt on the glass.

When the coating is prepared using a ground, heterogeneous dry powder material, the average mottling rating is usually 4.
~5. In contrast, when a powder spray composition is formed from a plurality of hollow, generally spherical particles, the average mottling rating is between 2 and 3, and is not infrequently as low as 1.5. this is,
This is a substantial improvement over the mottle rating obtained using ground material, and is also a good mottle rating to bring the glass to market.

Although specific embodiments of the method of the present invention have been described above, it will be obvious to those skilled in the art that various changes and modifications can be made without departing from the present invention, and such All changes and modifications that are included within the true spirit and scope of the invention are intended to be included within the scope of the appended claims.