Compounds and compositions for coating glass and coated glass substrates

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DESCRIPTION

Method and procedure for coating glass, composites and compositions for coating glass and coated glass substrates.

This invention relates to a method and apparatus for the chemical vapor deposition of one or more different metal oxides on a substrate, for example glass, to silicon-containing precursors used in the preparation of coating compositions containing silicon oxide and to the (to) product (s), for example coated glass, made therefrom.

It is known in the art that when a film of a transparent metal oxide, such as tin oxide, is deposited on a glass substrate, the coated glass substrate has non-uniform light reflection across the visible spectrum because of the difference in the refractive index between the metal oxide and the glass substrate. Furthermore, when the thickness of the metal oxide coating is not uniform, the coating tends to exhibit a multiplicity of interference color effects commonly referred to as iridescence. Such iridescence effects make coated glass aesthetically unacceptable for most architectural applications. Thus, various methods of masking such iridescence effects and / or reducing reflectance have been proposed.

A technique for minimizing or eliminating the refractive index difference between a metal oxide and a glass substrate is described in US-A-3,378,396 to Zaromb, where a glass substrate is coated by simultaneously directing separate sprays of a chloride solution. of tin and of a silicon chloride solution on a stationary glass piece heated in an oxidizing atmosphere, for example air. The heat from the glass piece thermally converts the metal chlorides to their metal oxides. The ratio of the sprays to each other is gradually varied to vary the ratio of the weight percent of the metal oxides in the coating. The resulting coating has a continuously changing composition throughout its thickness, for example near the glass-coating interface, the coating is predominantly silicon oxide, the surface of the coating furthest from the glass-coating interface is predominantly tin oxide and in between the coating consists of varying amounts of percent by weight of silicon oxide and tin oxide.

Strong describes in his publication entitled "Practical Applications of High and Low Reflecting Films on Glass", pages 441-443 of Le Journal de Physique et Le Radium, Vol. 11, July 1950, that a coating technique similar to that described by Zaromb reduces iridescence of the coated article.

Additional techniques using Zaromb's ideas to coat a mobile substrate are described in US-A-4,206,252 and 4,440,882. These patents further describe the deposition of a second fluorine-doped tin oxide composite coating on the first coating of the type described by Zaromb.

Gordon describes in US-A-4,187,336 and 4,308,316 the reduction of iridescence of a tin oxide coating on a glass substrate using an intermediate coating between the tin oxide coating and the glass substrate having a thickness and refractive index that satisfies the optical equation: the index of refraction of the intermediate coating is equal to the square root of the refractive index of the glass substrate times the index of refraction of the tin oxide coating.

US-A-4,377,613 and 4,419,386 describe a reduction in iridescence arising from a tin oxide film on a glass substrate by providing two intermediate coating layers between the glass substrate and the tin oxide. The intermediate layer near the surface of the glass substrate has a high refractive index, while the intermediate layer furthest from the surface of the glass substrate and next to the tin oxide film has a lower refractive index.

In general, the patents cited above, with the exception of US-A-4,206,252 and 4,440,822, describe coating a stationary glass substrate. Apparatus for coating a mobile glass substrate with metal oxides are described in US-A-4,206,252 and 4,440,882 noted above and in US-A-4,853,257 and US-A-4,386,117.

In US-A-4,206,252 and 4,440,882 the underside of a movable hot glass tape is coated by directing coating compositions containing metal compounds towards the surface of the tape, the compounds of which are converted to their corresponding metal oxides.

US-A-4,853,257 describes an apparatus for depositing a low-emissivity film on a glass tape by directing coating reagents containing metal in vapor form onto the top surface of a glass tape while the glass tape is supported on a molten metal bath contained in a non-oxidizing atmosphere. Carrier gas, unreacted coating composition and decomposition by-products are removed from the coating zone through an exhaust port on each side, and equidistant, from the position where the coating reagents in vapor form are directed toward the glass tape.

US-A-4,386,117 describes a process for depositing a mixed metal oxide coating on a glass substrate by directing a gaseous mixture onto a moving glass belt and then expelling gases from the coating zone at two positions equidistant from the inlet of the gas mixture to the coating zone.

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FR-A-25 18 429, corresponding to US-A-4,446,815, describes an apparatus for continuously coating a mobile substrate such as glass. The nozzle has three converging nozzles to deliver SnCl4 and H2O reagents to deposit SnO2 layers. It is described that the substitution of SnCl4 for TiCl4 results in a deposition of a layer of TiO2. The SnO2 layer can be doped with fluorine or antimony respectively.

US-A-3,674,453 describes the modification of the surface characteristics of glass by sodium, potassium, antimony, bismuth, lead, tin, copper, cobalt, manganese, chromium, iron, nickel, silver, silicon or titanium to provide layers of uniform color. Vapor from a composite metal is directed to the hot glass surface treatment zone.

EP-A-499 524, corresponding to US-A-5,286,295, describes the deposition of a gaseous coating composition on a moving hot glass belt supported on a molten metal bath. This reference does not refer at all to the chemical nature of the coating.

From the figure and the specification herein it is apparent that the coating composition is delivered by a central injection port and is divided into two streams directed up and down the nozzle to achieve a relatively thick coating.

EP-A-499 523 describes a nozzle structure for coating floating glass by pyrolysis of a gas mixture. The gas mixture is directed onto the glass surface through a chamber and the excess is removed by the chamber. Figures 2 and 3 represent a second suction line to remove lost gas to avoid contamination of the atmosphere of the floating glass chamber.

US-A-5,122,391 describes chemical vapor deposition of indium tin or doped and undoped indium tin oxide films. Depositing a SiO2 precoat is also indicated.

US-A-4,922,853 describes online vapor phase chemical deposition. Metal oxide coatings are prepared by decomposition of a reagent including an organometallic or other metallic compound or mixtures thereof with or without a suitable dopant.

Although each of the apparatus and processes described in the aforementioned patents is acceptable for its intended purpose, there are limitations when the apparatus and processes are used to apply the coating to a movable heated glass substrate, for example a glass tape supported on a bath of molten metal contained in a non-oxidizing atmosphere. Therefore, it would be advantageous to provide apparatus and processes for depositing the coating on a heated mobile substrate as well as the metal-containing precursors used in preparing the coating.

One of the limitations of the currently available vapor vapor coating system for coating a glass ribbon moving at rapid speeds, for example, of approximately 15.24 meters / minute (600 inches / minute) is that the coating mixture In vapor phase it does not have enough time to deposit a coating of acceptable thickness on the glass tape. The article titled “The LPCVD of Silicon Oxide Films Below

400 ° C (700 ° F) From Liquid Sources ”by AK Hochberg and DL O'Meara published in J. Electrochem. Soc. Vol. 136, No. 6, June 1989, property of The Electrochemical Society, Inc. pp. 1843 and 1844 describe the use of trimethylphosphite to accelerate coating deposition below 400 ° C (750 ° F). The publication "User's Guide For: Glass Deposition with LTO-410 ™ Source Material" by Dr. A. Hochberg and Dr. B. Gelernt, Copyright 1990 by Schumacher of Carlsbad, California, 92009 discloses that the LTO-410 process is not significantly changed with the addition of trimethylphosphite.

Although the use of accelerators is disclosed, such accelerators are not disclosed to be beneficial at elevated temperatures for example above 400 ° C (750 ° F). Therefore, it would be advantageous to provide accelerators for coating systems that operate at temperatures above about 536 ° C (1000 ° F).

The object of the invention is achieved with a transparent substrate that has a coating composed of at least two different metal oxides and that has an atomic percentage greater than 0 and up to 15 of an element dispersed through it selected from the group consisting of phosphorus, aluminum and boron, where the mixed metal oxide itself excludes phosphorus, aluminum and boron and the coating have regions of continuously varying ratio of the different metal oxides as the distance from the substrate-coating interface to the opposite surface increases and with the substantial absence of strata of a fixed ratio of the different metal oxides.

The solution includes a method of depositing a vapor phase coating composition containing metallic precursor compounds on the surface of a mobile substrate by the steps of: directing the vapor phase coating composition toward a first predetermined position on the surface of the substrate, moving a first portion of the vapor along a first region of the substrate surface in a first direction that is parallel to the direction in which the substrate is moving, and a second portion of the vapor along a second region of the substrate surface in a second direction opposite the first direction and maintain the first portion of the coating composition in the first region of the substrate surface for a period of Longer time than the second portion of the vapor in the second region of the substrate to coat the substrate, and ejecting the first and second portions of said steam on each side of said first predetermined position

ES 2 201 065 T3 after different periods of contact with the substrate surface, where the vapor phase coating composition contains at least two different metal-containing precursors in an oxygen-containing carrier gas to provide a coating having a continuously variable chemical composition of metal oxides as the distance from the substrate-coating interface to the opposite surface increases.

Another embodiment of the invention relates to a coating apparatus for depositing a vapor phase coating composition containing metal precursor compounds on the surface of a mobile substrate including:

(i) means for directing a vapor phase coating composition towards the surface of said substrate, (ii) first exhaust means spaced a distance "x" from said vapor directing means on its side, (iii) second exhaust means spaced at a distance "y" from said vapor directing means on its other side and in alignment with said vapor directing means and said first exhaust means, (iv) first discharge means on the outer side of the first exhaust means to direct an inert gas towards the surface of said substrate, (v) second discharge means on the outer side of the second exhaust means to direct a gas inert towards the surface of said substrate, each of the discharge means providing an inert gas curtain to prevent coating vapors from moving from the coating zone between the discharge means to atmosphere outside the coating apparatus, and also to prevent the atmosphere from moving to the coating area.

The invention relates to a transparent substrate, for example a glass substrate having a coating composed of mixed metal oxides, for example silicon oxide and tin oxide. The coating composition has a continuously changing ratio of silicon oxide to tin oxide as the distance from the glass-coating interface increases, for example substantially all of the silicon oxide at the glass-coating interface and substantially all of the oxide of tin on the opposite coating surface. Between the glass-coating interface and the opposing coating surface there are minimal, or no, layers of a fixed ratio of silicon oxide to metal oxide and small amounts of phosphorus, boron, and / or aluminum are dispersed in the coating when used. compounds containing said elements as accelerators to increase the rate of coating deposition and control the morphology of the coating.

The invention also relates to a vapor phase coating composition having a silicon-containing precursor having the structural formula

R3-Si-O-R1 |

R4 where R1 is selected from groups including alkyl and alkenyl. R2 is the functional group that gives the silicon compound the ability to easily convert to silicon oxide and includes hydrogen, halogen, alkenyl and halogenated alkyl radicals. R3 is a bridging group to provide multi-atom silicon compounds and includes -S- and -N- groups.

R4 completes the bonding of the base silicon atom.

Furthermore, the invention relates to a coating composition having mixed metal-containing precursors, for example tin- and silicon-containing precursors. The silicon metal precursor may include compounds containing

-Si-Oantes described and an accelerator capable of improving the reaction rate of coating compounds. Accelerators include Lewis acids and Lewis bases.

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Brief description of the drawings

Figure 1 illustrates a coated substrate incorporating features of the invention and obtained using the apparatus, processes, and coating materials of the invention.

Figure 2 is an elevational view of a coating system having two coating stations, one of which includes a coating apparatus having multiple coating zones incorporating features of the invention.

Figure 3 is a view similar to Figure 2 of a coating apparatus having a coating zone incorporating features of the invention.

Fig. 4 is a graph showing a gradient overlay and an enhanced and extended gradient overlay deposited in accordance with the ideas of the invention.

Figure 5 is a graph showing the effect of the height of the coating apparatus from the surface of a glass substrate and carrier flux on the ratio of tin oxide to silicon oxide in the coating deposited on the glass substrate according to the ideas of invention.

Figure 6 is a graph showing the effect on film thickness using the accelerators of the present invention.

Description of preferred embodiments

Referring to Figure 1, a coated article 10 is shown that incorporates features of the invention and that can be made using the coating materials, processes, and apparatus of the invention. In general, article 10 includes a substrate 12, for example, but not limiting the invention, clear or colored plastic and / or glass, having a coating 14 that exhibits minimal reflected color having a continuously variable index of refraction, and preferably has lower emissivity than uncoated substrate. In the explanation below, the substrate is a glass substrate. Coating 14 is generally composed of a mixture of silicon oxide and a metal oxide, such as tin oxide. As in Zaromb, discussed above, coating 14 has a continuously changing composition as the distance from the glass-coating interface 16 increases. In general, near the glass-coating interface 16, the coating is predominantly silicon oxide, while on the opposite surface 18 of coating 14, for example, the surface of the coating furthest from the glass-coating interface 16, the composition of the coating is predominantly tin oxide. The predominantly tin oxide region may continue to be predominantly tin oxide for a thickness that requires the use of the article. For example, when an article with high emissivity is desired, for example close to the emissivity of the glass substrate, the predominantly tin oxide region is thin; When a low emissivity article is desired, the predominantly tin oxide region is thicker. The tin oxide region can be doped with fluorine or antimony as described in US-A-3,677,814 to further reduce emissivity. Between the glass-coating interface 16 and the opposing surface 18, the coating 14 is composed of continuously varying amounts of silicon oxide and tin oxide as the distance from the glass-coating interface 16 increases. In other words, as the distance from the coating glass interface 16 increases, each subsequent region of the continuously variable composition in coating 14 contains a different weight percent ratio of tin oxide to silicon oxide from the preceding region and, although without limiting the invention, said ratio tends to increase in general as the glass-coating interface distance 16 increases. The opposing surface 18 is predominantly tin oxide, that is, the weight percent silicon oxide in the outer region approaches zero, and the weight percent tin oxide approaches 100.

Although coating 14 was explained using a coating of tin oxide and silicon oxide, the invention is not limited thereto, and as will be appreciated from the following explanation, any two or more different metal oxides can be used in the practice of the coating. invention.

The coated article 10 of Figure 1 was produced using the coating system 19 depicted in Figure 2. An explanation of the coating apparatus 20 in Figure 3 will now be presented for a better appreciation of the characteristics of the coating system 19 depicted in Figure 2. The apparatus 20 of Figure 3 can be used to deposit an inhomogeneous coating of the type discussed above on the glass substrate 12. In Figure 3 as in Figure 2, the substrate 12 is a glass ribbon 22 or pieces cut from it.

With reference to Figure 3, the coating apparatus 20 is supported in any convenient way above and spaced from the glass tape 22 supported in a tank or bath 24 of molten metal contained in a chamber having a non-oxidizing, non-oxidizing atmosphere. shown, for example of the type of camera described in US-A-4,853,257. As seen in Figure 3, the glass ribbon 22 moves from left to right under the coating apparatus 20, for example, through a coating position. As will be appreciated, the invention is not limited to the chamber, not shown, containing the molten metal bath, nor to a non-oxidizing atmosphere, and any chamber design having any such atmosphere may be used in the practice of the invention. as other processes for moving a heated substrate by a coating apparatus that realizes the features of the invention.

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In general and without limiting the invention, tape 22 has a thickness range of from about 0.08 inch to about 0.50 inch (about 2 to about 13 millimeters) and moves at speeds of about 700 to about 100 inches (about 17.80 meters to approximately 2.54 meters) per minute, respectively. Molten tin bath 24 has a temperature on the order of about 538 ° C (1000 ° F) to about 1094 ° C (2000 ° F).

The apparatus 20 includes an elongated coating unit 25, two elongated exhausts 28 and 26, one on each side of the coating unit 25, and two elongated discharge units 31 and 32, one on each outer side of an exhaust, as shown depicted in Figure 3. The term "elongated" as used herein means that the coating unit, the exhausts and the discharge units extend across the width of the belt, that is, transverse to the movement of the belt. tape 22. The discharge units 31 and 32 provide an inert gas curtain to prevent the coating vapors from the coating zone, that is, the zone between the discharge units 31 and 32, from moving into the chamber atmosphere and also to prevent the atmosphere in the chamber from moving into the coating area. As can be seen, the separation between the coating zone and the chamber atmosphere is necessary because the atmosphere in the coating zone, as will be explained, is an oxidizing atmosphere, and the chamber atmosphere, as explained previously. , it is a non-oxidizing atmosphere. In the practice of the invention, the inert gas was nitrogen.

The exhausts 26 and 28 according to the ideas of the invention are not equally spaced from the coating unit 25. More specifically, advancing the glass ribbon from left to right as shown in figure 3, the exhaust 28 is more closer to the coating unit 25 than the exhaust 26. By placing the exhausts at different distances from the coating unit, the coating vapors are in contact with the surface of the belt for different periods of time. Therefore, all other parameters being equal, for example, glass temperature, spacing between coating unit and glass strip surface, and exhaust pressures, a thicker coating will be deposited on the tape as it passes between exhaust 26 and coating unit 25 than between coating unit 25 and exhaust 28. This feature of the invention will be more fully appreciated in the explanation of the coating system 19 shown in Figure 2.

As can now be appreciated, the design of the discharge units 31 and 32, the exhausts 26 and 28, and the coating unit 25 do not limit the invention. The invention has been practiced using exhausts 26 and 28 with an elongated hole 36 connected to a collection chamber 38 and using discharge units 31 and 32 with an elongated hole 50 connected to a discharge chamber 46. The inert gas has uniform pressure and constant velocity along the length of hole 50 to provide a curtain of inert gas, a portion of which flows into the chamber atmosphere (not shown) and a portion to the adjacent exhaust 26 or 28 as shown in figure 3.

The coating unit 25 includes a discharge chamber 56. The coating vapor exits the chamber 56 through the elongated hole 58 and is directed towards the surface of the glass strip 22 passing under the hole 58. The coating vapor has a uniform pressure and constant velocity along the length of hole 58 and has sufficient pressure to allow a portion of the coating vapor to flow upward and a portion to flow downward as seen in Figure 3.

The amount of nitrogen typically introduced by each discharge unit 31 and 32 is on the order of 20 to 300 standard cubic feet per minute for a belt having a width of approximately 4.06 meters (160 inches). As can be appreciated, the flow rate of the nitrogen does not limit the invention; however, it should be sufficient to provide an inert curtain separating the coating zone and the chamber atmosphere.

The holes 36 of the exhausts 26 and 28 and the exhaust pressure are regulated to expel a portion of the inert gas from the adjacent discharge unit 31 and 32, respectively, and a portion of the coating vapor from the coating unit 25. As seen in Figure 3 and as explained above, exhaust 26 is more spaced from liner unit 25 than exhaust 28. With this arrangement and keeping the exhaust pressure identical for each exhaust unit, the residence time of the coating vapor is longer for the glass ribbon 22 as it travels from the exhaust 26 towards the coating unit 25 than for the glass ribbon. as it travels from the coating unit 25 towards the exhaust 28.

Although the above asymmetric arrangement is preferred, because of its simplicity, the invention is not intended to be limited thereto, since the discovery here resides in the fact that having different coating vapor residence times on different sides of a Coater unit alters the final composition of the coating. Therefore, other suitable apparatus or processes can be used to obtain such an effect. It has been determined that the same effect as that achieved with asymmetrically arranged exhausts, as explained above, can also be achieved even with symmetrical spacing of the covering unit 25 and the exhausts, for example, by adjusting the height or level of the holes 36 of the exhausts 26 and 28 relative to each other and to the glass ribbon. Another method of varying the residence time of the coating vapor is to vary the flow ratio from exhaust 26 to exhaust 28.

By way of illustration only, in the case where the spacing between the coating unit 25 and the exhausts 26 and 28 is symmetrical, reducing the pressure of the exhaust 26 below the pressure of the exhaust 28 results in the residence time of the coating vapor between the coating unit 25 and the exhaust 26 is greater than the residence time of the coating vapor between the coating unit 25 and the exhaust 28.

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Referring now to Figure 2, coating system 19 was used to apply coating 14 to the coated article 10 depicted in Figure 1. Coating system 19 includes a coating station 59 for applying a graded composition coating and a coating station 60 to spread the thickness of the tin oxide region predominantly on the surface 18 of coating 14 (see FIG. 1). Coating station 59 includes coating units 61, 62, and 64, exhausts 66, 68, 70, and 72, and discharge units 31 and 32. Coating station 60 does not limit the invention; however, the coating station used in the practice of the invention was the type of coating apparatus described in US-A-4,853,257, the ideas of which are incorporated herein by reference. The hole 50 of the discharge unit 31 is spaced approximately 63.5 cm (25 inches) from the hole 50 of the discharge unit 32; hole 74 of exhaust 66 is spaced approximately 57 cm (22-1 / 2 inches) from hole 50 of discharge unit 32; hole 76 of coating unit 61 is spaced approximately 51 centimeters (20 inches) from hole 50 of discharge unit 32; hole 78 of exhaust 68 is spaced 44.5 cm (17-1 / 2 inches) from hole 50 of discharge unit 32; hole 80 of coating unit 62 is spaced approximately 32 centimeters (12-1 / 2 inches) from hole 50 of discharge unit 32; the hole 82 of the exhaust 70 is spaced approximately 25.4 centimeters (10 inches) from the hole 50 of the discharge unit 32; hole 84 of cover unit 64 is spaced approximately 12.7 centimeters (5 inches) from hole 50 of discharge unit 32, and hole 86 of exhaust 72 is spaced approximately 6 centimeters (2-1 / 2 inches) from hole 50 of discharge unit 32. Coating station 60 was spaced about 1.8 meters (6 feet) from discharge unit 32.

Holes 50, 74, 76, 78, 80, 82, 84, and 86 were conveniently spaced approximately 0.51 cm (0.2 inches) above the top surface of glass ribbon 22 as seen in Figure 2. The length of the holes 50 was approximately 64 centimeters (25 inches); the length of holes 74, 78, 82 and 86 was approximately 64 centimeters (25 inches) and the length of holes 76, 80 and 84 was approximately 53.34 cm (21 inches). The width of the holes 50 was approximately 0.32 centimeter (0.125 inch); the width of holes 74, 78, 82 and 86 was approximately 0.64 centimeter (0.250 inch) and the width of holes 76, 80 and 84 was approximately 0.15 cm (0.06 inch). Nitrogen and coating vapor flows were about 350 to about 700 SLPM (standard liters per minute). The exhaust flow was about 375 to about 770 SLPM. The glass ribbon speeds were between approximately 5.08-17.78 m (200,000 inches) per minute, the temperature of the glass ribbon entering, passing and exiting coating stations 59 and 60 was between approximately 635 -675 ° C (1170-1250 ° F).

The coating system 19 and in particular the coating station 59 and the associated method are especially effective for the chemical vapor deposition (CVD) of coatings from mixtures of silicon and metal-containing precursors to obtain the article 10 represented in the Figure 1.

In the following explanation, coating 14 is made from a mixture of tin-containing precursors and silicon-containing precursors capable of volatilizing and converting to their corresponding oxides in the presence of oxygen at temperatures on the order of 400 ° C to 815 ° C (750 to 1500 ° F). As will be appreciated, the invention is not limited thereto and other metal-containing precursors can be used with the coating apparatus and in the coating processes discussed above.

Examples of silicon compounds that can be used in the practice of the invention include, but are not limited to, tetraethoxysilane, silane, diethylsilane, di-t-butoxydiacetoxysilane, and the silicon compounds described in US-A3,378,396 of ZarombyUS-A-4,187. 336,4,308,316,4,377,613,4,419,386,4,206,252,4,440,822 and 4,386,117.

Compounds that have been used in the practice of the invention include diethylsilane, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, diethyldichlorosilane, tetramethylcyclotetrasiloxane, and triethoxysilane.

In addition to the silicon-containing precursors discussed above, the invention contemplates silicon-containing precursors that can be converted to their corresponding silicon oxides and can be used in admixture with the metal-containing precursors to form the desired coating on a substrate, for example a substrate. glass having a coating with the desired mixed oxide gradient.

When looking for a silicon-containing precursor to form a silicon oxide coating, those skilled in the art would normally choose a precursor with an Si-O bond because it is one of the most difficult bonds to break, as evidenced by the stability of the mineral quartz (SiO2 ). Therefore, breaking the Si-O bond in the precursor and rearranging it into a lattice containing the desired silicon oxide bonds for a coating is difficult, for example the siloxane bond requires high temperature and / or long periods of time to form a corresponding coating of silicon oxide. For this reason, those skilled in the art will not expect silicon-containing precursors having the siloxane structure to be useful in forming a silicon oxide coating on a mobile substrate.

It has been determined, however, that if a compound bearing an Si-O bond also carries at least one specific functional group, it will increase the reactivity of the silicon-containing precursor bearing the Si-O bond, and hence its rate of coating formation, although the strength of the bonds would not appear to indicate any appreciable change in their coating formation behavior. Functional groups that are capable of giving the silicon-containing precursor containing an Si-O bond the ability to readily convert to a silicon oxide coating include hydrogen, halogens, vinyls, and α-chlorinated alkyls. The reactivity of

ES 2 201 065 T3 silicon-containing precursor can then be tailored by appropriate choice of functional groups. The silicon-containing precursor of the present invention is not limited to having only the above-defined substituents. Provided that one or more of the functional groups defined above is present in the silicon-containing precursor carrying the Si-O bond, other groups, such as alkyls and other more fully defined substituents below, may also be present without an effect. Significantly detrimental to the overall reactivity of the silicon-containing precursor.

Compounds bearing the Si-O bond can be exemplified by reference to the following structural formula I:

R3 — Yes — O — R1 |

R4 where R1 is selected from Group A below consisting of compounds that do not have an available oxygen to form the peroxide bond:

alkyl or substituted alkyl radicals having 1 to 10, preferably 1 to 4, carbon atoms, such as

-CH3, -CH2CH2CH3 and -CH2CH2OH;

halogenated or perhalogenated alkyl radicals having 1 to 10, preferably 1 to 4, carbon atoms, such as -CCl3, -CH2CHClCH3 and -CH2CCl2CCl3;

alkenyl or substituted alkenyl radicals having 2 to 10, preferably 2 to 4, carbon atoms, such as -CH = CHCH3 and -CH = CH2;

alkynyl or substituted alkynyl radicals having 2 to 10, preferably 2 to 4, carbon atoms, such as -C = C-CH3 and -C = CH; and aryl or aralkyl or substituted aryl or aralkyl radicals having 6 to 11, preferably 6 to 9, carbon atoms, such as -C6H5 and -C6H4CH3;

where R2 are functional groups that form a bond with the Si atom that is easily thermally broken, for example, at temperatures between 93.5 ° C-445 ° C (200 ° F-800 ° F) and preferably between 205 ° C- 370 ° C (400 ° F-700 ° F). The functional group (R2) capable of giving the silicon-containing precursor the ability to easily become a silicon oxide coating is selected from Group B consisting of:

hydrogen;

halogen, preferably Cl;

alkenyl or substituted alkenyl radicals as defined in Group A for R1;

α-halogenated alkyl or perhalogenated alkyl, and substituted alkynyl or alkynyl radicals as defined in Group A for R1;

where R3 is a bridging group to provide compounds of multiple silicon atoms. R3 is selected from Group C consisting of:

—S—;

—N — R5 where R5 is an alkyl or substituted alkyl radical having 1 to 10, preferably 1 to 4, atoms | carbon, such as -CH2CH3 or -CH2CH2CH3;

—N—;

| —P — H;

| —P — R5 where R5 is as defined above.

—P—

ES 2 201 065 T3

H |

-CI

Hn where n is 1 to 10, preferably 1 to 4, and where R4 completes the bond at the base silicon atom. R4 is selected from Groups A and B above and Group D below consisting of:

alkoxide or substituted alkoxide radicals having 1 to 10, preferably 1 to 4, carbon atoms, such as -OCH₂CH₃;

alkyl or substituted alkyl radicals having 1 to 10, preferably 1 to 5, carbon atoms, such as -CH2CH3;

-CN;

-OCN, and

-PH2;

alkylphosphines, and dialkylphosphines, where the alkyl radical has 1 to 10, preferably 1 to 4, carbon atoms, such as -PHCH3 and -P (CH2CH3) 2.

The substituents for Groups A, B and D explained above can be selected from the following Group E consisting of:

an alkoxide radical having 1 to 10, preferably 1 to 4, carbon atoms, such as -OCH2CH2CH2 CH3;

an alkyl radical having 1 to 10, preferably 1 to 4, carbon atoms, such as -CH2CH2CH3;

a halogen or a halogenated alkyl radical having 0 to 10, preferably 0 to 4, carbon atoms, such as Cl or -CCl3;

an alkenyl radical having 2 to 10, preferably 2 to 4, carbon atoms, such as -CH = CH2; an alkynyl radical having 2 to 10, preferably 2 to 4, carbon atoms, such as -C ^ CH; an aryl or aralkyl radical having 6 to 11, preferably 6 to 9, carbon atoms, such as -C6H5;

-CN;

-OCN;

phosphine, alkylphosphine, and dialkylphosphine radicals, where the alkyl group has 1 to 10, preferably 1 to 4, carbon atoms, such as -PH2, -PHCH3,

-P (CH2CH3) 2, and

-OH.

Various compounds can be formed from base structure I. When a molecule containing a single silicon atom is desired, R3 can be selected from Groups A, BoD. When multiple silicon atom molecules are desired, R3 is a bridging group . In the case of multi-atom silicon molecules, R3 directly connects two silicon atoms. When molecules of multiple silicon atoms are cyclic, R4 is not present on any of the silicon atoms. When the multisilicon molecules are straight or branched chain molecules, the R4 groups are present only on the silicon atoms in the chain termination position. When molecules with more than two silicon atoms are desired, the bridging groups, R3, can be the same or different.

Another type of bonding is possible to create molecules of multiple silicon atoms with Si-O-Si bonds. In this case, R1 is no longer selected from Group A and instead is another silicon support group from base structure I with the continued requirement to have a R2 selected from Group B. The bond between the silicon support groups is chosen such that a direct Si-O-Si bond is formed. If a molecule with more than two silicon atoms is desired, R4 is only present at the terminating silicon atoms as described above. R3 se

ES 2 201 065 T3 can now select from Groups A, B, C or D. By selecting R3 from Group C it is possible to create molecules of multiple silicon atoms with different bridging groups, i.e. Si-O-Si-N -Yes.

As can now be appreciated, simple or complex silicon-containing precursors are possible. The only remaining requirement is that each silicon atom has directly attached an oxygen atom and a functional group selected from Group B.

Specific compounds that have been used in the practice of the invention include tetramethylcyclotetrasiloxane, tetramethyldisiloxane, and triethoxysilane. Specific compounds that can be used in the practice of the invention, but not limited to, are methyldimethoxysilane, dimethylmethoxysilane, trimethoxysilane, dimethylchloromethoxysilane, methylchlorodimethoxysilane, chlorotrimethoxysilane, dichlorodimethoxysilane, trichloromethoxysilane, triethoxyloxymethyloxysilane; tetramethylcyclotetrasiloxane, triethoxysilane, chlorotriethoxysilane, pentachloroethyltriethoxysilane, and vinyltriethoxysilane.

Metal-containing precursors that can be used in admixture with the silicon-containing precursors defined above in the chemical vapor deposition of mixed oxides on a glass substrate include metal-containing precursors that are vaporizable at or below about 260 ° C (500 ° C). F) and that they will react with a gas containing oxygen to form the corresponding metal oxides. Preferably, but not limiting the invention, compounds that can be used include metal-containing organometallic compounds including, but not limited to, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, arsenic, selenium. , yttrium, zirconium, niobium, molybdenum, cadmium, rhodium, ruthenium, palladium, indium, antimony, tellurium, tantalum, tungsten, platinum, lead, bismuth, aluminum and tin. Of these metal compounds, tin compounds are highly preferred. Examples of tin compounds usable herein include those defined by the following structural formula II:

^R7

R6 — Sn — R8

R9 II where R6, R7, R8 and R9 are the same or different and include, but are not limited to, halogens preferably Cl or F, an alkyl radical having 1 to 10, preferably 1 to 4, preferably 6 to 9, carbon atoms, such as -C6H5. Any other organic or inorganic functional group may be used in the practice of the invention provided that the vapor pressure of the resulting compound is at least 0.01 pounds per square inch absolute, below about 260 ° C (500 ° F ).

The silicon-containing precursors defined above, including those bearing the Si-O bond, can be used alone, or they can be used in admixture with the organometallic compounds explained above in the chemical vapor deposition of the corresponding single or mixed oxides on a substrate. of glass. However, when the silicon-containing precursor is used alone, or in admixture with other metal-containing precursors, in the chemical vapor deposition of single or mixed oxides on a moving substrate, for example, coating a tape of advancing glass. Over a bath of molten metal or on a conveyor belt, it is desirable to have a sufficient silicon oxide deposition rate to coat the moving glass substrate. For example, when coating a moving glass tape and the silicon oxide deposition rate is relatively low, the speed of the glass tape has to be reduced. More specifically, to deposit a coating of approximately 1200 A thick on a glass belt moving at a linear speed greater than approximately 7.62 meters (300 inches) per minute, the deposition rate of all the components must be increased. classes of silicon-containing precursors used in chemical vapor deposition processes to achieve uniform coating.

Several materials have been identified that can be used to accelerate the rate of deposition of silicon oxides from their precursors. The type and functionality of each accelerant depends to some extent on the silicon-containing precursors with which it will be used. Combinations have been determined for a specific coated article and for the process used to deposit the desired coating, in particular, the mixed oxide of the invention. It has also been determined that there is a synergistic effect between some combinations of precursors and accelerators that result in beneficial alteration and control of the morphology of the coating.

Accelerators that can be used in the practice of the invention to increase the rate of deposition of silicon oxide alone or in combination with another oxide, eg, tin oxide, can be defined as follows:

(1) Lewis acids, such as trifluoroacetic acid and hydrochloric acid.

(2) Lewis bases, such as NaOH, NaF, CH3OH, CH3OCH3 and S (CH3CH2) 2.

(3) Water.

(4) Nitrogen, phosphorus, boron, and sulfur compounds having the following structural formulas:

ES 2 201 065 T3 (a) R_nI

R10-Y-R12, (b) r_or

I

RlO^-S ~ Ri2

I

Rl3 (c) R10-S-R11 (d) Rn

I

Rio-P⁼0

To go₁₂ and (θ) Rll Rl4 \ /

RlO^-P ~ Rl2

I

Rl3 where Y is selected from the group consisting of nitrogen, boron, and phosphorus and R10, R11, R12, R13, and R14 are selected from the following list of functional groups, hereinafter referred to as Group F:

hydrogen;

halogens, preferably Cl;

alkenyl or substituted alkenyl radicals having 2 to 10, preferably 2 to 4, carbon atoms, such as -CH = CH2;

perhalogenated alkyl or substituted alkyl radicals having 1 to 10; preferably 1 to 4 carbon atoms, such as -CClH2 or halogenated alkyl or substituted alkyl radicals having 1 to 10, preferably 1 to 4, carbon atoms, such as -CCl₂CH₂CH₃;

acyloxy radicals having 1 to 10, preferably 1 to 4, carbon atoms, such as -OCOCH3;

alkynyl or substituted alkynyl radicals having 2 to 10, preferably 2 to 4, carbon atoms, such as -C ^ CH;

alkyl or substituted alkyl radicals having 1 to 10, preferably 1 to 4, carbon atoms, such as -CH3, -CH2CH2CH3;

aryl or substituted aryl radicals having 6 to 10, preferably 6 to 9, carbon atoms, such as -C6H4CH3;

ES 2 201 065 T3 alkoxide or substituted alkoxide radicals having 1 to 10, preferably 1 to 4, carbon atoms, such as -OCH2CH2CH3;

where said substituents are from Group E explained above, examples of said compounds include, but are not limited to, triethylphosphite, trimethylphosphite, trimethylborate, PF5, PCl3, PBR3, PCl5, BCl3, BF3, (CH3) 2BBr, SF4 and HO3SF. Triethylphosphite was used in the practice of the invention.

(5) Aluminum compounds having the following structural formula III can be used to accelerate the deposition rate of silicon-containing precursors alone or in combination with other metal-containing precursors (the "other metal-containing precursors", as can be appreciated, do not include precursors containing aluminum):

R15 |

R17 — Al — R16 III where R15, R16 and R17 are the same or different and selected from the following Group G: hydrogen;

halogens, preferably Cl;

-O-R17, where R17 is a linear, branched or substituted alkyl radical having 1 to 10 carbon atoms, preferably 1 to 4, with substituents selected from Group E explained above;

S-R18, where R18 is equivalent to R17 defined above;

-NH2;

R19-N-R20, where R19 and R20 are linear or branched alkyl groups, or substituted alkyl groups having 1 to 10, preferably 1 to 4, carbon atoms, with substituents selected from Group E explained above; (minus the phosphine groups, such as -PH2); Y

N R21, where R21 forms a cyclic group having 2 to 10 preferably 2 to 6 carbon atoms, with substituents selected from Group E explained above (minus the phosphine groups).

(6) Ozone.

The mechanism that causes the accelerators of the invention to increase the rate of deposition is not fully understood. Although the mechanism is not fully understood, the results, explained below, clearly demonstrate that the mixed oxide coating deposition rate was increased. Referring to Table 2 in Example I below, runs 11 and 12 contain the accelerator triethylphosphite. The growth rate of the silicon oxide coating was at least twice the rate of the silicon oxide coating from run number 2 that did not have any accelerators.

A moving glass substrate was coated using the same precursor chemistry as used in passes 11 and 12 of Table 2 and similar deposition rates resulted. The precursors were vaporized at a temperature of 65 ° C (150 ° F) to 260 ° C (500 ° F), and the gaseous mixture of the precursors, gases containing oxygen, and carrier gas and accelerator, were put in contact with a glass tape supported in a bath of molten metal and heated to a temperature of approximately 510 ° C (950 ° F) to approximately 730 ° C (1350 ° F). The glass ribbon advanced at a speed of 4.25 to 18.00 meters (170 to 730 inches) per minute. The amounts of the components that can be used in the practice of the invention are defined below in Table 1.

TABLE 1

Mole percent

<td>Compound</td><td>Wide range</td><td>Preferred range</td>

<td>Precursor containing metal</td><td>0.005 to 5.0</td><td>0.1 to 2.0</td>

<td>Silicon-containing precursor</td><td>0.0001 to 5.0</td><td>0.05 to 2.0</td>

<td>Gas containing oxygen</td><td>1.0 to 99.0</td><td>5.0 to 50.0</td>

<td>Accelerating</td><td>0.0001 to 10.00</td><td>0.01 to 2.0</td>

ES 2 201 065 T3

When substrate 12 (see figure 1), for example glass substrate, is subjected to chemical vapor deposition of mixed oxides, for example a mixture of silicon oxide and tin oxide, to obtain coating 14 according to In the process of the invention, the coating 14, as explained above, is characterized by having a continuously variable composition as the distance from the glass-coating interface 16 increases, resulting in a substantial reduction in iridescence in the coated product. Assuming a coating composed substantially of silicon oxide and tin oxide, said portion of the coating next to the glass-coating interface 16 is composed to a large extent of silicon oxide and as the distance of the glass-coating composition increases, each subsequent region of the composition Continuously variable contains a ratio of silicon oxide to tin oxide that varies as the distance from the glass-coating interface increases. More specifically, the percentage of silicon oxide decreases as the percentage of tin oxide increases, so that when the opposite surface 18 is reached, the region is predominantly made up of tin oxide. The thickness of the predominantly tin oxide region can then be increased to reduce the emissivity of the coated article.

It has been determined that when chemical vapor deposition of mixed oxides is carried out on a glass substrate with the addition of one or more of the accelerators of the present invention, for example, phosphorus, aluminum, or boron compounds, a small amount of the base atom, eg phosphorus, aluminum or boron, dispersed in coating 14. The presence of phosphorus, aluminum and / or boron in the coating affects the morphology of the resulting coating such that such continuously changing components are less likely to form layers with discrete composition, for example, layers that have a fixed ratio of oxide to silicon to tin oxide for thicknesses greater than approximately 70 A. Additionally, the presence of phosphorus, aluminum and / or boron affects the morphology of the resulting coating, decreasing the percentage crystallinity (which is close to 0% crystallinity) and therefore reducing the light scattering properties that can be observed as haze. The amount of the phosphorus, aluminum or boron compound incorporated in the layer is a function of the process variables. In the practice of the invention, a glass ribbon moving at speeds of between 425 to 1800 centimeters (175 to 730 inches) per minute, and having a temperature on the order of 637 ° C (1180 ° F) to 660 ° C (1220 ° F) with a gas mixture having a phosphorus compound as an accelerator; the mole fraction of the accelerant was 0.01 to 0.5. An atomic percentage of phosphorus from 1 to 12 dispersed in the coating was found. The invention encompasses using an accelerator amount of an atomic percent greater than 0 and up to 15 with a preferred range of 1 to 5 atomic percent. The present invention will be better appreciated and understood from the description of the following specific examples:

Example I

Various compositions were prepared from precursors containing silicon and monobutyltin chloride to illustrate the higher growth rate of mixed oxide films on a glass substrate in accordance with the ideas of the invention. In each composition, monobutyltin chloride with different silicon-containing precursors was used. The precursors were vaporized, when necessary, and the resulting gaseous mixture of precursors, oxygen and nitrogen was introduced into a quartz tube which was electrically heated and controlled to maintain a temperature of 150 ° C (300 ° F). The concentration of the silicon-containing precursors was in all cases 0.30 mole percent, the monobutyltin chloride 0.50 mole percent, oxygen 21 mole percent, the remainder being nitrogen. The speed of the precursors and carrier gas was maintained at a speed of 30 centimeters per second in the quartz tube. This gas mixture was passed over a glass substrate heated to approximately 650 ° C (1200 ° F), for 3 to 30 seconds, after which the spent gas mixture was vented to a chemical hood. The film thickness for all passes, except for pass number 8 explained below, was measured using a Tencor P1 profilometer. The film growth rate was calculated by dividing the film thickness by the coating time. The data obtained are shown below in Table 2.

(Table goes to next page)

ES 2 201 065 T3

TABLE 2

<td>Past number</td><td>Silicon-containing precursors</td><td>Growth rate, A / second</td>

<td> 1</td><td>Diethylsilane</td><td> 129</td>

<td> 2</td><td>Tetraethoxysilane</td><td> 43</td>

<td> 3</td><td>di-t-butoxydiacetosilane</td><td> 64</td>

<td> 4</td><td>tetramethylcyclotetrasiloxane</td><td> 181</td>

<td> 5</td><td>tetramethylcyclotetrasiloxane</td><td> 205</td>

<td> 6</td><td>tetramethylcyclotetrasiloxane</td><td> 177</td>

<td> 7</td><td>tetramethyldisiloxane</td><td> 164</td>

<td> 8</td><td>ethyltriacetoxysilane</td><td> 110*</td>

<td> 9</td><td>Triethoxysilane</td><td> 139</td>

<td> 10</td><td>methyldiacetoxysilane</td><td> 32</td>

<td> 11</td><td>tetraethoxysilane + 0.31 mol percent triethylphosphite</td><td> 136</td>

<td> 12</td><td>tetraethoxysilane + 0.09 mol percent triethylphosphite</td><td> 87</td>

* Estimated

Run 1 was used as the control because it is generally accepted that diethylsilane has an acceptable deposition rate.

The tetramethylcyclotetrasiloxane precursors used in passes 4, 5 and 6 were obtained from different suppliers. Runs 2, 3, and 10 using silicon-containing precursors having an Si-O bond without the accelerators or functional groups of the present invention had an expected low growth rate. Pass numbers 4, 5, 6, 7 and 9 that had an Si-O bond with the functional group of the present invention had a deposition rate equal to or better than control pass number 1. In addition, pass number 2, when increased with an accelerator as described in the present invention (see passes numbers 1 1 and 12), exhibited a deposition rate greater than pass number 2 and approached (Pass number 12) or (Pass number 11) exceeded the deposition rate of control pass number 1.

Run number 8 is a compound having the Si-O bond that does not contain a functional or accelerating group of the present invention; however, it showed a deposition rate equal to control pass number 1. The film quality of pass number 8 was extremely poor and the film thickness had to be estimated using interference colors that were different from the measurement technique. used for past numbers 1-7 and 9-12. Example II

Two passes were made showing the advantages obtained by using an asymmetric coater configuration of the present invention rather than a symmetric coater configuration. Referring to Figure 3, the exhausts 26 and 28 were positioned in one pass relative to the coating unit 25 such that x / y = 2 where "x" is the distance between the exhaust 28 and the coating unit. 25 and "y" is the distance between the coating unit 25 and the exhaust 28, while in the other embodiment, the exhausts 26 and 28 were positioned relative to the coating unit 25 such that x / y = 1 . The coating vapor composition was maintained at 166 ° C (337 ° F) and contained 1.2 mole percent monobutyltin chloride, 0.3 mole percent tetraethoxysilane, 0.5 mole percent triethylphosphite, 1.0 mole per cent. percent water, 20 mole percent oxygen, and nitrogen balance. The floating soda-lime-silica glass ribbon supported and moving through a bath of molten metal had a thickness of about 0.300 centimeter (0.118 inch), a temperature of about 650 ° C (1200 ° F), and a linear speed of 13 meters (510 inches) per minute. The surface of the nitrogen curtain holes provided by the discharge units 3 1 and 32 and the exhausts 26 and 28 was maintained at a height of approximately 0.55 cm (0.22 inch) above the surface to be coated glass tape 2.

The average height of tin irregularities of a film produced on the glass tape using both asymmetric and symmetric coating configurations is plotted in Figure 4. Film analysis was performed using the Rutherford Backscatter Spectrometry technique. (RBS) for the purpose of comparing the gradient film produced by the two coating configurations. The RBS spectra in Figure 4 were taken at a special angle to obtain optimal depth resolution of the distribution of tin atoms through the film.

A comparison of the asymmetric coater configuration (shown by solid line 210) with that of the symmetric coater configuration (shown by dashed line 212) is plotted in the RBS spectra in Figure 4. Between the two mean heights of the irregularities of tin 210 and 212 is significant the extended region

ES 2 201 065 T3 of tin signal from 2025 keV at 3.7 relative counts down to 1890 keV at 1.4 relative counts compared to symmetric coater which has its variable tin signal from 2025 KeVC to 3.6 counts relative to 1940 keV to 1.4 relative counts. This difference shows an increase in film thickness for an asymmetric coater configuration. As can be seen from Figure 4, the asymmetric coater configuration provides gradient coating with an extended range of variable composition.

Example III

A series of passes were made using the coating apparatus 20 of Figure 3 where the exhausts 26 and 28 were positioned relative to the coating apparatus 20 such that x / y = 1. The coating vapor composition was maintained at 165 ° C (320 ° F) and contained 0.8 mole percent monobutyltin chloride, 0.3 mole percent tetraethoxysilane, 0.1 mole percent triethylphosphite, 0.54 mole percent one hundred water, the balance being air. Total gas flow and cover height were varied while concentrations were kept constant. The results obtained are shown in the process contour graph in figure 5. By altering the height of the coater in inches and the carrier flow in standard liters per minute, the boundary layer conditions in the coating zone are altered, thereby altering the relative ratio of deposited tin oxide and silicon oxide. The process contour plot shows how these other two techniques, ie, coater height and volumetric feed, alter the coating composition on the glass substrate.

As depicted in Figure 5, increasing the carrier flux for a given coating unit increases the ratio of tin oxide to silicon oxide. In other words, the tin oxide weight percent increases as the silicon oxide weight percent decreases. Raising the height of the coating unit for a given carrier flow lowers the ratio of tin oxide to silicon oxide, that is, the tin oxide weight percent decreases as the silicon oxide weight percent increases. Example IV

Several passes were made to show the effects of water and triethylphosphite on the thickness of a mixed oxide film at a constant vapor residence time. The process chart, Figure 6, was developed using experimental design data. The coating unit 25 shown in Figure 3 was used with the exhausts 26 and 28 positioned relative to the coating unit 25 such that x / y = 1. The precursor vapor was kept at 165 ° C (320 ° F) and contained 0.8 mole percent monobutyltin chloride, 0.3 mole percent tetraethoxysilane. The triethylphosphite (TEP) and water were varied and sufficient air was added to obtain a volumetric feed rate of 500 standard liters per minute. The glass ribbon 22 had a thickness of 0.300 centimeter (0.118 inch), a temperature of 650 ° C (1200 ° F), and a linear speed of 13 meters (510 inches) per minute. The coating unit 25 was held at a height of 0.56 cm (0.22 inch) above the surface of the glass tape. Note the substantial effect exhibited by the presence of triethylphosphite on the thickness of the coating. When the mole percent of triethylphosphite was increased, the thickness of the coating increased. Increasing the mole percent of the water also increases the thickness of the coating.

Example V

The article 12 of Figure 1 was produced using the coating station 59 depicted in Figure 2, in conjunction with the coating station 60 described in Henery. Coated articles were produced at three glass thicknesses, that is, at three different speeds of the glass ribbon to demonstrate the flexibility of the process. Coating station 59 was used to produce a coating ranging from predominantly silicon oxide composition at the glass-coating interface 16 to predominantly pure tin oxide and coating station 60 produced a predominantly tin oxide spread thickness.

The coating station 59 had three coating units 61, 62 and 64 with holes 76, 80 and 84 respectively, and four exhausts 66, 68, 70 and 72. The exhausts 66 and 68 were positioned relative to the coating unit 61 in a symmetrical configuration while exhausts 68 and 70 and exhausts 70 and 72 were arranged in an asymmetric configuration around their respective cover units 62 and 64. In addition, coating station 59 had two discharge units 31 and 32 each with a hole 50. The distance between holes 74 and 76, 76 and 78, 80 and 82, 84 and 86 was approximately 7.08 cm (2 -3/4 inches). The distance between holes 80 and 78, and between 84 and 82 was approximately 5-1 / 2 inches (14.0 cm).

To effect the desired change in coating composition, different chemical feed rate ranges are required in each of the coating units 61, 62, and 64. The chemical concentrations necessary to produce the desired composition change are also a function of the speed of the glass strip. Examples of typical benchmarks are listed in Table 3. In each of these cases the carrier gas was air, which was maintained at a temperature of approximately 160 ° C (320 ° F). The total gas flow from the discharge units 31 and 32 was maintained at approximately 500 standard liters per minute. Coating station 59 was spaced approximately 0.59 centimeter (0.22 inches) above moving glass ribbon 22. The predominantly tin oxide extended region was deposited at plating station 60 using the ideas of US-A-4,853,257.

ES 2 201 065 T3

The equation

X a * 2 + b · 2) generally used by those skilled in the art to quantify the color observability of an object is explained by Hunter in Food Technology, Vol. 32, pages 100-105, 1967 and in The Measurement of Appearance, Wiley and Sons, New York, 1975. A coated glass product having a Hunter value of 12 or less is considered to exhibit no appreciable observable color. Table 3 under the column titled Color Saturation Index lists the Hunter value measured for the samples. As you can see, all the samples had a color saturation index of less than 12.

TABLE 3

<td>Show_nor</td><td>MBTC Unit 61 mol%</td><td>MBTC Unit 62 mol%</td><td>MBTC Unit 64 mol%</td><td>TEOS Unit 61 mol%</td><td>TEOS Unit 62 mol%</td><td>TEOS Cell 64 mol%</td>

<td> 1</td><td> 0,280</td><td> 0,190</td><td> 0,490</td><td> 0,050</td><td> 0,050</td><td> 0,020</td>

<td> 2</td><td> 0,290</td><td> 0,300</td><td> 0,600</td><td> 0,100</td><td> 0,160</td><td> 0,300</td>

<td> 3</td><td> 0,350</td><td> 0,200</td><td> 0,940</td><td> 0,300</td><td> 0,300</td><td> 0,270</td>

<td> 4</td><td> 0,400</td><td> 0,200</td><td> 0,940</td><td> 0,300</td><td> 0,300</td><td> 0,330</td>

<td> 5</td><td> 0,600</td><td> 0,758</td><td> 0,790</td><td> 0,390</td><td> 0,400</td><td> 0,350</td>

<td> 6</td><td> 0,500</td><td> 0,600</td><td> 1,200</td><td> 0,265</td><td> 0,300</td><td> 0,100</td>

MBTC stands for Monobutyltin Trichloride

TEOS stands for tetraethoxysilane

<td>Show n °</td><td>TEP Unit 61 mol%</td><td>TEP Unit 62 mol%</td><td>TEP Unit 64 mol%</td><td>WATER Unit 61 mol%</td><td>WATER Unit 62 mol%</td><td>WATER Unit 64 mol%</td>

<td> 1</td><td> 0,300</td><td> 0,100</td><td> 0,025</td><td> 0,170</td><td> 0,600</td><td> 0,600</td>

<td> 2</td><td> 0,280</td><td> 0,110</td><td> 0,039</td><td> 0,180</td><td> 0,330</td><td> 0,630</td>

<td> 3</td><td> 0,280</td><td> 0,120</td><td> 0,070</td><td> 0,150</td><td> 0,610</td><td> 0,370</td>

<td> 4</td><td> 0,280</td><td> 0,100</td><td> 0,050</td><td> 0,150</td><td> 0,610</td><td> 0,370</td>

<td> 5</td><td> 0,266</td><td> 0,120</td><td> 0,066</td><td> 0,150</td><td> 0,180</td><td> 0,640</td>

<td> 6</td><td> 0,400</td><td> 0,300</td><td> 0,288</td><td> 0,400</td><td> 1,000</td><td> 1,000</td>

TEP stands for triethylphosphite

<td>Sample no.</td><td>Glass temperature ° F</td><td>Glass speed inches / minute</td><td>Saturation index color</td><td>Gradient thickness A</td><td>Thickness of oxide of tin A</td>

<td> 1</td><td> 1230</td><td> 340</td><td> 5,0</td><td> 1200</td><td> 4000</td>

<td> 2</td><td> 1234</td><td> 340</td><td> 5,0</td><td> 1100</td><td> 4000</td>

<td> 3</td><td> 1194</td><td> 340</td><td> 2,3</td><td> 1250</td><td> 3700</td>

<td> 4</td><td> 1200</td><td> 340</td><td> 3,6</td><td> 1150</td><td> 3650</td>

<td> 5</td><td> 1190</td><td> 490</td><td> 8,9</td><td> 850</td><td> 1750</td>

<td> 6</td><td> 1200</td><td> 700</td><td> 4,6</td><td> 1000</td><td> 1700</td>