FI89585C - CONTAINER CONTAINER FOR GLASS PRODUCTS - Google Patents

Description

1 69585

Continuous vapor deposition process for making a coated glass product. - Kontinuerligt ängavlagringsförfrande för framställning av en belagd glasprodukt.

The present invention relates to a continuous process for the production of a coated glass product, in particular a coated architectural glass, and to a coated product thus produced. A particular embodiment of the invention relates to a chemical vapor deposition process for producing a glass product coated with a silicon layer formed by treatment with a non-oxidizing gas of monosilane (SiH4), a silica layer formed by oxidizing a silicon layer, with oxidizing gas. The invention also includes washing the coated glass article with dilute hydrofluoric acid to prevent film formation during subsequent tempering of the coating.

U.S. Patent 4,019,887 to "Kirkbride et al." shows the manufacture of architectural glass by coating with silicon formed by carrying out a continuous chemical treatment with a non-oxidizing gas containing monosilane. Kirkbride et al. the method disclosed in the patent is suitable for carrying out one step of the method according to the present invention, namely the step of forming a silicon coating layer on the glass product.

The addition of ethylene to the monosilane non-oxidizing gas disclosed in Kirkbride et al. Is disclosed in U.S. Patent 4,188,444, "Landau", and the advantage of using this ethylene is that the silicon coating significantly improves its alkali resistance.

U.S. Patent 4,187,336 to Gordon, 2,09585, discloses the use of tetramethyltin and other organotin compounds to make tin oxide coatings on glass by chemical vapor deposition.

U.S. Patent 4,100,330, "Donley", discloses the manufacture of a glass article having a surface coated with a silicon layer prepared by the method of the Kirkbride et al. Patent and further coated with a metal oxide layer deposited on silicon. According to the Donley patent, the metal oxide layer can be formed by spraying a solution of a silicon-coated glass product according to the Kirkbride et al. , iron acetylacetonate, chromium acetylacetonate and nickel acetylacetonate. According to the test data in the Donley patent, the Kirkbride et al. Silicon coating comes off when both cerium oxide and pumice are used in 20 brush abrasion tests and immersion for 30 seconds in hot sodium hydroxide solution, while sometimes directly on the glass surface and sometimes on Kirkbride et al. the metal oxide coatings applied to the silicon coatings of the patent do not come off by abrasion test treatments or by immersion in hot sodium hydroxide solution.

Most architectural glass is made by a method using the term "Float Glass Process" and some of which is shown in the drawings of the Kirkbride et al. Patent. In this method, the glass is poured into a suitably closed molten tin bath, the glass is transferred to rolls in line with the bath after sufficient cooling, and the glass is cooled as it passes on rollers first through a glass cooling furnace and finally exposed to ambient conditions. During the "float" or floating stage of the process, the non - oxidizing environment is maintained in contact with the tin bath to prevent oxidation, while the atmospheric environment is maintained in the glass cooling furnace.

It is clear that if it is desired to coat the glass first with silicon and secondly with tin oxide or some other oxide, it would be advantageous to do so so that the coating is associated with the manufacture of glass by the "Float Glass Process" method. As disclosed in the Kirkbride et al. Patent, the glass is at a suitable temperature in the flotation step of the method to perform the silicon coating application treatment; it is also at a suitable temperature in some parts of an air-containing glass cooling furnace to treat its surface with an oxidizing gas in tetramethyltin to form a layer of tin oxide on the silicon. However, when gas distributors were installed in the float glass line to treat the glass first at about 632 ° C in a non-oxidizing environment and secondly at about 607 ° C and surrounded by air, the glass on the production line was first treated with 86% nitrogen, 4% ethylene and 10% ethylene. by volume of monosilane and secondly by a gas with 99% by volume of air and 1% by volume of tetramethyltin, successive layers of silicon, tin oxide formed in the glass, but the appearance of the coated glass was not aesthetically acceptable due to defects called "pinholes" . In general, the coated glass had a translucent bronze color and a reflective silver color but had several, usually round small areas of holes that were lighter in transmitted light.

4,89585

The present invention is based on the finding that glass produced by the "Float Glass Process" can be coated immediately after casting, first with silicon and secondly with tin oxide or another oxide, provided that the treatment forming the tin or other oxide coating is carried out after the previously applied silicon layer is sufficiently oxidized. The method according to the invention is characterized by the things set forth in the characterizing part of claim 1.

One figure shown in the drawings is a schematic and vertical section of an apparatus for performing the "Float Glass Process" process, further comprising two gas distribution devices suitably positioned to carry out the process of the present invention.

According to the drawings, the apparatus shown in reference numeral 10 for performing the "Float Glass Process" method includes a float compartment 11, a glass cooling furnace 12 and a cooling compartment 13. The float compartment 11 includes a tin bath base 15, a lid 16, side walls (not shown) and walls 17 forming seals. that a closed compartment 18 is created in which an oxidized environment is maintained as described in more detail below to prevent oxidation of the tin bath 15.

When the device 10 is used, molten glass is poured into the bottom furnace 20 as indicated by reference numeral 19, from where it flows under the dosing wall 21 and down to the surface of the tin bath 15, from where it rises to rollers 22 and passes through the glass cooling furnace 12 and cooling compartment 13.

The non-oxidizing environment is maintained in the flotation compartment 11 by supplying to the compartment 18 a suitable gas having, for example, 99% by volume of nitrogen and 1% by volume of hydrogen, the supply being through pipes 23 operatively connected to the main pipe 5 89565 24. The gas is supplied to the compartment 18 from the pipes 23 at a sufficient rate to compensate for losses (part of the atmosphere leaves the compartment 18 by flow under the walls 17) and, for example, 0.001 to 0.01 atmospheres to maintain a slight overpressure above the environment. The metal bath 15 and the closed compartment 18 are heated by radiant heat directed downwards from the heaters 25. The environment or atmosphere in the glass cooling furnace 12 is air, while the cooling compartment is not closed and ambient air is blown into the glass by fans 26.

The device 10 also includes a gas distributor 27 in the flotation compartment 11 and a gas distributor 28 in the glass cooling furnace 12.

The following example illustrates the presently preferred mode of use, but which is provided solely to illustrate and clarify the invention and not to limit it.

Example

Device 10 was used to perform the method of the invention by making a coated glass sheet. The bottom 20 of the furnace was charged with heat-absorbing, bronze-colored glass containing about 14% by weight of Na 2 O, 73% by weight of SiO 2, 8.5% by weight of CaO, 0.32% by weight of Fe 2 O 3, 0.19% by weight of AlaOa, 0.01% by weight of TiO 2, 4% by weight of MgO, 0.003% by weight of C0304 and 0.0015% by weight of Se and this glass were made to flow over the tin bath 15 as a plate 3.6 m wide and 6.4 mm thick. This plate was passed through the device 10 at a speed of about 7.6 m / min. The temperature of the glass was 1093eC at the bottom of the furnace 20. In compartment 18 was a non-oxidizing environment or atmosphere 6 89585 maintained by supplying gas from pipes 23 0.006 atmospheres to maintain the overpressure above the environment? the gas contained 99% by volume nitrogen and 1% by volume hydrogen.

No measures were taken to adjust the atmosphere in the glass-cooling furnace; for this reason, the oxidizing environment in it was air. As it passed through the dispenser 27, the glass was treated with a gas containing 86% by volume of nitrogen, 10% by volume of monosilane and 4% by volume of ethylene, and as it passed under the dispenser 28, it was treated with a gas containing 99% by volume of air and 1% by volume of tetramethyltin. After the glass was cooled to about 38 ° C in the cooling compartment 13, it was washed schematically in the acid scrubber shown at 29 with about 4% by weight hydrofluoric acid for about 10 seconds. Nitrogen gas flowed from dispenser 27 at a rate of 0.065 nor-cubic meters per minute, while air / tetramethyltin gas flowed from dispenser 28 at 0.28 normal-cubic meters per minute. The glass progressed from the dispenser 27 to the exit end of the floatation compartment 11 in about 90 to 120 seconds, from the dispenser 27 to the dispenser 28 in about 8 minutes. The temperature of the glass was 635 ± 11 ° C under the dispenser 27? 521 ± 11 ° C under the dispenser 28.

The glass prepared as described in the example above had a multilayer reflective coating. The reflective coating was a 30 nanometer thick layer of silicon on top of the glass; there was a 2 to 5 nm thick silica film on the silicon and a 20 nm thick tin oxide film on the silica. The shading coefficient of the coated glass was 0.45 to 0.55, the daylight reflectivity was 45%, the daylight transmittance was 25%, and the sun transmittance was 30%. The color passed was a warm bronze color, a reflective color of a silver color. The coated glass was post-tempered; it has been found to be compatible with most insulating glass and glazing sealants, has excellent durability and low enough absorption to not require 7 89585 heat treatment. When the washing step with hydrofluoric acid was omitted, the coated glass had to be washed after tempering to remove the film formed during tempering.

The procedure described in the example above has also been used to coat gray, heat-absorbing glass with about 73 weight percent silica, 14 weight percent Na 2 O, 8.6 weight percent CaO, 4 weight percent MgO, 0.19 weight percent AlaO 3, 0.29 weight percent FeaO 3, 0.008 weight percent FeaO 3, 0.008 weight percent C0304, 0.001% by weight Se, 0.0086% by weight NiO and 0.01% by weight TiOa. The color passed through the final product was gray, the reflective color was silver; the shading factor was 0.45, daylight reflectance 45%, daylight transmittance 20%, and sunlight transmittance 29%.

The film is sufficiently absorbent so that it does not require heat treatment; the product was post-tempered, had excellent durability, and was suitable for use with most insulated glass and glazing seals.

When the procedure was repeated except that the washing step with hydrofluoric acid was omitted, there was a slight misting in the coated glass after tempering, which could be removed by washing. Hydrogen fluoride ... the washing step performed prevented the formation of mist.

It is to be understood that various changes and modifications may be made to the details of the invention set forth in the above example without departing from the spirit and scope of the invention as defined in the appended claims. In essential details, the invention is a continuous chemical vapor deposition process for making a coated glass article. The method comprises the steps of continuously moving the product hot past the first and then the second processing station. The first 8,89585 processing station is in a closed compartment where an unoxidized atmosphere is maintained. The oxidizing atmosphere is maintained in the vicinity of the second processing station. In the above example, the non-oxidizing atmosphere was maintained in a closed compartment containing the first treatment station by feeding a gas containing 99% by volume of nitrogen and 1% by volume of hydrogen. As can be seen from the results obtained by carrying out the method according to the example, such a atmosphere or environment is perfectly suitable. However, other inert gases could be used instead of nitrogen and the proportion of hydrogen could be increased or decreased as long as the required result is achieved, namely that the oxidation of the tin bath is prevented and the silicon layer is applied to the glass. Similarly, air was used in the process of the example to form an oxidizing environment in the glass cooling furnace 12, but other oxidizing media or atmospheres may also be used, such as air enriched with oxygen or nitrogen or even an inert gas other than nitrogen, as long as tin or the required deposition result of some other oxide coating without causing unnecessary damage to the glass cooling furnace itself.

In carrying out the present invention, a silane-containing non-oxidizing gas is directed against the surface of the product to form a silicon layer on this surface. In the above example, the silane was monosilane (SiH *). However, the treatment gas may contain other silanes in addition to or instead of the monosilane. Examples of other useful silanes include monochlorosilane (ClSiH3), dichlorosilane (Cl2SiH2), other halosilanes, alkoxysilanes, and di-tri- and upper silanes. Organosilanes, e.g. methyltrichlorosilane, are less preferred reactants than the silanes mentioned above because it is difficult to break the bond of silicon to 9,89585 carbon to form the desired silicon coating. Monosilane is currently the preferred treatment agent for reasons of cost and availability and because the by-product (hydrogen) of its use does not pose an environmental problem (unlike the above-mentioned chlorosilanes whose by-product is hydrogen chloride).

In the procedure of the above example, the glass was treated with a gas having 99% by volume of air and 1% by volume of tetramethyltin and directed to the glass from a dispenser 28. The purpose of this treatment was to form a tin oxide coating on the previously formed silicon / silica layers. An oxidizing environment is required to cause the tetramethyltin to deposit the tin oxide coating. Air is a suitable oxidizing gas to be used for this purpose, but air enriched with either oxygen or nitrogen or some other inert gas could also be used instead of air. A mixture containing more than about 1 1/2 volume percent tetramethyltin in air is highly flammable and should therefore be avoided. Other tin compounds can be used instead of tetramethyltin, for example stannous chloride and various organic tin compounds available. The use of dibutyltin diacetate to form a tin oxide coating on glass has been proposed (see Donley patent above); however, due to its low vapor pressure, this compound has been used as an organic solvent solution. For environmental and safety reasons, it is highly preferred to use tetramethyltin or some other tin or other metal compound that can be evaporated into air. In fact, titanium oxide coatings can be applied over silicon and silica layers using, for example, titanium tetrachloride, alumina coatings can be formed using, for example, diethylaluminum chloride, silica coatings using, for example, dichloroethane oxide and .

In the above example, the glass temperature at dispenser 27 was 635 ± 11 ° C and below gas dispenser 2Θ at 521 ± 11 ° C; the residence time of the glass in the oxidizing environment (air) of the glass cooling furnace 12 was about 6 minutes before treating the glass with the air / tetramethyltin gas from the dispenser 28; the non-oxidizing gas from the dispenser 27 contained 86% by volume nitrogen, 10% by volume monosilane and 4% by volume ethylene; and the oxidizing gas from the dispenser 28 contained 99% by volume air and 1% by volume tetramethyltin. These temperatures and gas mixtures are all important variables in carrying out the process of the invention. In general, the glass must be at a sufficiently high temperature for the gas from the dispenser 27 to be able to form a silicon layer and the gas from the dispenser 28 to form a metal oxide layer. The upper temperature limit is determined by the physical properties of the glass; it must be low enough to make the viscosity of the glass high enough to withstand the necessary treatments. In general, both the rate of silicon layer formation and the rate of metal oxide layer formation vary as a direct function of temperature. In this case, if lower temperatures are used, the silicon and metal oxide layers are formed at slower rates, and if too low temperatures are used, several dispensers are needed to form these layers sufficiently thick. The rate of formation of the layer or coating also varies according to the treatment chemicals used; for example, chlorosilanes form silicon coatings at lower temperatures than monosilane with other factors being the same. As indicated above, preferred treatment compounds for use in carrying out the n 89565 process of the present invention include monosilane and tetramethyltin. It is preferred that the surface of the glass be at least 593 ° C when treated with monosilane and that the glass be at least 398 ° C when treated with tetramethyltin. Finally, the reflective silicon coating must be sufficiently oxidized prior to the use of the metal compound to form the metal oxide coating so that perforation does not occur to such an extent that the result would be aesthetically unacceptable. The time required for sufficient oxidation can be shortened by raising the temperature or raising the partial pressure of oxygen, or conversely, the time can be increased by lowering the temperature or lowering the partial pressure of oxygen. It has been found that the degree of oxidation required to avoid perforation depends on the temperature at which the treatment with tin tetrachloride or the like is carried out. In the embodiment of the above example, the glass temperature was, for example, 521 ± 11 ° C during the tetramethyltin treatment, and a silicon oxide film having a thickness of 2 to 5 nm was formed on the silicon. However, it has been found that perforation occurs when the tetramethyltin treatment is performed at a temperature of 632 ° C, but that the tetramethyltin treatment can be performed at this temperature without perforation if the silica coating has a thickness of 6 to 9 nm.

The procedure of the above example included a washing step in which the coated glass was washed with dilute hydrofluoric acid, in particular with 10% by weight hydrofluoric acid for 10 seconds. As explained above, a film or clouding will form on the coated glass product during tempering if this washing step is omitted. Although the film, which is usually a bluish-white stain defect, can be washed from the product after the tempering is completed, it is highly advantageous to produce a product in which no film is formed after the initial production of the product during subsequent tempering or other treatment.

Therefore, when carrying out the process according to the invention, a washing step of 4 seconds with 4% by weight of hydrofluoric acid or a corresponding washing step is preferably used. It has been found that both the hydrofluoric acid concentration and the length of the washing step can be varied from those used in the above example. For example, 7.6 cm x 15.2 cm glass samples with coatings prepared as described in the example above were used, except that the washing step was omitted, and the shortest possible immersion time in three different concentrations of hydrofluoric acid was determined to prevent subsequent film formation. in the tempering to be performed.

Half of each sample tested was immersed in hydrofluoric acid and then the sample was tempered at 704 ° C for 5 minutes. It was found that film formation during tempering was prevented by immersing the sample in 3% by weight hydrofluoric acid for 10 seconds or longer, by immersing the sample in 6% by weight hydrofluoric acid for 8 seconds or longer. Immersion for up to 15 seconds in hydrofluoric acids at these three concentrations did not visibly degrade the glass or coating. Extrapolation of the above data reveals that film formation can be prevented by immersion in 10% by weight hydrofluoric acid for up to only 4 seconds and that even only 2 1/2% by weight dilute hydrofluoric acid can be used to prevent film formation by extending the immersion time to about 12 seconds; likewise, it is clear that other acid washes may be used provided that they comply with the above, preventing film formation during tempering without adversely affecting the coating or glass. Stirring the acid, for example during the washing of the coating with a brush, is advantageous because it brings new acid to the surface.

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It is clear from the above disclosure that the present invention is a continuous chemical vapor deposition or coating process for producing a coated glass product. The method includes the steps of continuously advancing the hot product past the first and second successive processing stations, at least the first of which is located in a closed compartment. The non-oxidizing environment is maintained in the part of the closed compartment where the first processing station is located, while the second processing station is in the oxidizing environment. The silane-containing non-oxidizing gas is directed from the first treatment station against the surface of the product to form a silicon layer on this surface. The oxidizing gas containing the metal compound in the vapor phase is directed from the second processing station against the coated surface of the glass product. The temperature of the glass product, its residence time in the oxidizing environment in which the second processing station is located, the non-oxidizing gas composition from the first processing station and the oxidizing gas composition from the second processing station are all controlled so that the silane-containing gas forms a reflective silicon layer on the glass surface. oxidation before the product arrives at the second processing station forms a layer of silicon oxide on the silicon that is thick enough so that substantially no small holes are formed in the metal oxide layer.

In the procedure described in the example above, the non-oxidizing gas used in the dispenser 27 to apply the reflective silicon layer contained ethylene in addition to monosilane and nitrogen. Ethylene is important because it changes the nature of the silicon layer on the treated glass. It has been shown that chemically the change is the formation of a combined silicon / silicon carbide layer on the glass; however, attempts to detect silicon carbide in the coating by analytical means have failed 14 89585. In any case, it is clear that the coating changes because its alkali resistance is significantly improved compared to the durability of a silicon layer made using only nitrogen and monosilane. It has been found that other ethylenically unsaturated aliphatic hydrocarbons, acetylenically unsaturated aliphatic hydrocarbons and even aromatic hydrocarbons can be used instead of ethylene, provided in each case that they are allowed to evaporate. However, due to their higher toxicity, all other unsaturated hydrocarbons are less preferred than ethylene. A small amount of ethylene or another unsaturated hydrocarbon, for example 4 to 5% by volume, in the presence of 9 to 13% by volume of silane and the remainder of nitrogen or another inert gas, is the preferred treatment gas for preparing the silicon coating obtained by the process of the present invention.

It will be apparent to those skilled in the art that other changes and modifications may be made to the details of the invention described above without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (17)

A method of producing a coated glass article which comprises steps for continuously pre-feeding the article in hot state past a first and a second successive processing station (27, 2Θ) of which at least the first is in a closed zone (18), maintaining a non-oxidizing atmosphere in the closed zone, in which the first treatment station is located, maintaining an oxidizing atmosphere around the second treatment station and the adjacent glass, and a non-oxidizing medium containing a screen is directed from the first treatment station to a surface the article for forming a silicon coating and wherein an oxidizing medium containing a metal compound is directed from the second treatment station to the coated surface of the glass article, characterized by the temperature of the operating glass article, the residence time in the oxidizing atmosphere around the second treatment. as well as the composition of the non-oxidizing medium from the first treatment station and the composition of the oxidizing medium from the second station, such that the silane-containing medium forms a reflective silicon coating on the glass surface, the oxidizing medium containing a metal forms a coating of a metal oxide, and by oxidation, before the article reaches the second treatment station, a silicon oxide layer is formed on the silicon having a thickness sufficient to substantially free the metal oxide layer from "craters", and the silicon oxide layer has a thickness of about 2 pm 2. A method according to claim 1, characterized in that the coating media is in meadow phase when directed to contact with the article. 3. A process according to claim 2, characterized in that the non-oxidizing steam medium containing a sieve also contains an unsaturated hydrocarbon in such amount that it imparts alkali resistance to the silicone coating. 4. A process according to claim 3, characterized in that the non-oxidizing steam medium contains about 4-5% by volume of unsaturated hydrocarbon, from 9% to 13% by volume of sieve, and the balance is nitrogen. Process according to claim 4, characterized in that the unsaturated hydrocarbon is ethylene. 6. A process according to any of claims 2-5, characterized in that the oxidizing meadow medium containing a metal compound consists of about 99% by volume of air and 1% by volume of tetramethyltin. Process according to any one of claims 2-6, characterized in that said glass surface is at a temperature of at least 593 ° C when treated with said non-oxidizing meadow medium, contains a sieve and is at least at 398 ° C. when the treatment with the non-oxidizing meadow medium containing a metal compound is carried out. Method according to claim 6, characterized in that the residence time in the oxidizing atmosphere around the second treatment station is sufficient for a silica coating to be formed with a thickness ranging from 2 to 5 nm on the silicon coating, and said oxidizing gas treatment. is carried out at a temperature of 521 ± 110 ° C 9. A method according to claim 6, characterized in that the residence time in the oxidizing atmosphere around the second treatment station is sufficient to form a silica coating having a thickness between 6 - 9 nm, and said oxidizing gas treatment is carried out at a temperature of about 632. ° C. 21 89585 10. A process according to any of claims 2-9, characterized in that, after cooling to a sufficiently low temperature, the surface coating of the glass article is washed with dilute hydrofluoric acid and that the temperature of the glass when washed, the time of the washing step. and the concentration of the hydrofluoric acid is controlled so that neither the glass article nor the coating thereon is substantially destroyed, while the formation of a film ρά the coated article upon subsequent curing is prevented. 11. A process according to claim 10, characterized in that the hydrofluoric acid is stirred during the washing step and that the duration of the washing step runs between about 4 seconds and about 12 seconds, while the concentration of the hydrofluoric acid rises between about 2% and about 10% by weight. Method according to any of the preceding claims, characterized in that said glass contains a heat-absorbing, bronze-colored compound and the coated glass article has a shadow factor of between 0.45 and 0.55. 13. Coated article characterized in that it contains a glass substrate and a reflective silicon coating which adheres to the surface of the substrate, a silicon oxide layer adjacent to the silicon surface, adhering to the substrate, and a metal oxide coating which adheres to silica which adheres to silica. shall be substantially free from "craters", ie the silica layer has a thickness which is at least about 2 nm. 14. The article according to claim 13, characterized in that the surface coating of the article has been subjected to an acid wash to enable curing of the article without the formation of a film thereon. 22 89585 The article according to claim 13 or 14, characterized in that said silica layer has a thickness which ranges between about 2 and 5 nm. 16. An article according to claim 13 or 14, characterized in that said silica layer has a thickness ranging from about 6 to 9 nm. 17. An article according to any of claims 13-16, characterized in that said metal oxide layer is made of tin oxide.