MXPA99010635A - Solar control coated substrate with high reflectance - Google Patents

Abstract

A solar control coated substrate with high reflectance (RL) and comprises a pyrolytically-formedcoating layer containing oxides of tin and antimony in a Sb/Sn molar ratio of from 0.01 to 0.5, characterised in that the coating layer further contains an additive comprising one or more of aluminium, chromium, cobalt, iron, manganese, magnesium, nickel, vanadium, zinc and zirconium and is free from fluorine, whereby the so-coated substrate has a reflectance of at least 10%. The invention covers a process for making such a coated substrate and a glazing panel incorporating such a coated substrate.

Description

Substrate covered with solar radiation control with high reflectance.

The present invention relates to a coated substrate with solar radiation control with high reflectance and to a method for making said coated substrate. Transparent panels for solar radiation control have become very required to be used as exterior glazing for buildings. Besides presenting an aesthetic appeal, they offer advantages in the provision of protection against solar radiation and its effects of dazzlement, providing the occupants of the building with a screen against excessive heat and intense light. The panels include at least one sheet of a transparent substrate material, typically a calcium sodium glass, which has a coating that provides the specific properties required. The control of solar radiation requires that the panel does not let pass a too high proportion of total incident solar radiation, preventing the overheating of the interior of the building. The transmission of the total incident solar radiation can be expressed in terms of "solar factor" (FS). As used herein, the term "solar factor" means the sum of the total energy directly transmitted and the energy that is absorbed and re-radiated from the opposite side to the energy source, as a proportion of the total radiant energy incident on the coated substrate. Although traditionally architects looking for glazed panels for use in buildings tend to favor panels with low levels of reflection, a change in the perception of the aesthetic appeal has led to an increase in the demand for panels with high levels of reflection, at the same time retaining a low solar factor. The properties of the coated substrate referred to herein are based on the standardized definitions of the International Commission on Illumination - Commission Internationale de l'Eclairage ("CIÉ"). "Light transmittance" (TL) is the flow transmitted through a substrate as a percentage of the incident light flux. The "light reflectance" (RL) is the flow of light reflected by a substrate as a percentage of the incident light flux. The "selectivity" of a coated substrate for use in a glazed building panel is the ratio between the light transmittance and the solar_factor_ (TL / FS). The "purity" (p) of the color of the substrate refers to the purity of excitation in the transmission or reflection measured with Illuminant C. It is specified according to a linear scale in which a light source defined white has a purity of zero _ and the pure color has a purity of 100%. Illuminant C (Illuminant C) represents average daylight with a color temperature of 6700 ° K. The term "refractive index" ("refractive index") (n) is defined in the CIÉ International Lighting Vocabulary (International Lighting Vocabulary CIÉ), 1987, page 138. The "dominant wavelength" ("dominant wavelength") ( D) is the peak wavelength on the scale transmitted or reflected by the coated substrate. Various techniques are known for forming coatings on a vitreous substrate, including pyrolysis. Generally, pyrolysis has the advantage of producing a hard coating, avoiding the need for a protective layer. The coatings formed by pyrolysis have durable properties and are resistant to abrasion and corrosion. It is believed that this is due in particular to the fact that the process involves the deposition of coating material on a substrate that is hot. Generally, pyrolysis is also more economical than alternative coating processes, such as vaporization, in particular in terms of investments in plants. A wide variety of coating materials have been proposed to modify the optical properties of the glazed panels. Tin oxide (Sn02) has been widely used, often in combination with other materials, such as other metal oxides. Our patent GB 1455148 deals with a method for pyrolytically forming a coating of one or more oxides (for example Zr02, Sn02, Sb2 03, Ti02, Co3 04, Cr2 03, SiO2) on a substrate, mainly by spraying the compounds of a metal or a silicon, in order to modify the transmission of light and / or the light reflection of the substrate. Our patent GB-2078213, which refers to a method for pyrolytically forming a coating by two separate sprays to achieve a high rate of coating formation, treats tin oxide coatings with addition of fluorine or antimony. Our patent GB 2200139 relates to the formation of a pyrolytic tin oxide coating from a precursor containing at least two additives, such as oxidizing agents, fluorine sources and metal sources. It has been found that the use of a tin oxide coating with a small proportion of antimony oxide offers several advantageous combinations of optical properties. Our patent applications GB 2302101 (101) and 2302102 (? 102) describe glazed panels against solar glare that include a layer of pyrolytic coating of tin and antimony oxides, in which the molar ratio Sb / Sn is 0.01 to 0.5. The coating 101 is applied by liquid spray and has a thickness of at least 400 nm, a light transmittance of less than 35% and a selectivity of at least 1.3. The coating x102 is applied by chemical vapor deposition (CVD) and has a solar factor below 70%. An object of the present invention is to provide a pyrolytically formed coated substrate, which has sunscreen properties and a high reflectance. It has been found that this and other useful objectives can be achieved by including certain, defined additives at the time of applying a pyrolytic coating that includes tin and antimony oxides on the substrate. Accordingly, according to a first aspect of this invention, a transparent substrate is provided with a pyrolytically formed coating layer, containing tin and antimony oxides in a Sb / Sn molar ratio of 0.01 to 0.5, characterized in that the coating layer also contains a selected additive. of the group comprising aluminum, chromium, cobalt, iron, manganese, magnesium, nickel, vanadium, zinc and zirconium, and which is free of fluorine, said substrate thus coated having a reflectance (RL) of at least 10%. The invention further provides a method for forming a transparent coated substrate, which comprises the pyrolytic deposition of a mixture of reagents in the substrate of a coating layer containing tin oxide and antimony in a Sb / Sn molar ratio of 0, 01 to 0.5, said reagent mixture comprising a tin source and a source of antimony, characterized in that said reagent mixture further contains an additive selected from the group comprising aluminum, chromium, cobalt, iron, manganese, magnesium, nickel, vanadium, zinc and zirconium and that is free of fluorine, said substrate thus coated having a reflectance (RL) of at least 10%. It has been found that a coating of tin oxides and antimony modified with an additive as described above (referred to herein as a "modified tin oxide / antimony coating" retains the anti-solar radiation properties of the coating without additive, but it also exhibits a much higher level of reflectance.A coated substrate according to the invention can be used as a single sheet glaze panel, or alternatively in a set of glazed panels or multiple laminate. In a set of glazed panels or multiple laminate it is preferable that only one of the sheets constituting it has said coating. Although the invention is described herein primarily with reference to glazing panels for buildings, the panels according to the present invention are suitable for other applications such as vehicle windows, in particular the transparent roofs of vehicles. Because coatings produced by pyrolysis generally have a higher mechanical strength than coatings produced by other processes, the choice of coating location can be made taking into account the properties obtained from the panel, rather than the reasons for protection of the coated surface against exposure to wear or corrosion.

The coated substrate sheets according to the invention preferably have a low solar factor of about 70% or less, more preferably at most 65%. In the case of multiple glasses, the location of the coating on the outside face, ie toward the energy source, generally improves the solar factor above that achieved when the coating is placed on the side opposite the energy source. The molar ratio Sb / Sn of the coating layer is preferably at least 0.03, more preferably at least 0.05. This ensures a high level of absorption. On the other hand, said ratio is preferably less than 0.21, with a view to achieving a high level of light transmittance (TL). More preferably, the ratio is less than 0.16, since above this level the coating layer exhibits an excessively high absorption level, as well as poor selectivity. It is desirable that the glazed panel transmits a reasonable proportion of visible light to allow both good natural lighting into the building or vehicle and good outward visibility. Accordingly, it is desirable to increase the selectivity of the coating, i.e. to increase the transmittance ratio with respect to the solar factor. Actually, it is preferable that the selectivity be as high as possible. The light transmission (TL) of a coated substrate according to the invention is typically between 35 and 76%, depending on the specific additive used. Preferably, the modified tin oxide / antimony coating has a thickness of 100 to 500 nm. As mentioned above with reference to prior art documents, such as GB 2078213, a previously proposed constituent element in tin oxide / antimony coatings was fluorine, formed for example from reagents containing tin, antimony and fluorine in ratios Sb / Sn = 0.028, F / Sn = 0.04. However, it has been found that the presence of fluorine tends to prevent the incorporation of antimony in the coating. For example, reagents containing antimony and tin "in a ratio Sb / Sn = 0.028 give a coating with a Sb / Sn ratio of about 0.057, while the same reagents plus a reagent containing fluorine in an amount such that F / Sn = 0.04 give a coating with a Sb / Sn ratio of around 0.038. Accordingly, fluorine is specifically excluded from the coatings of the present invention. Preferably, to ensure a high optical quality, any turbidity in the product should be less than 2%. Later in this description the possibility of reducing the clouding using a base coat layer will be discussed.

A preferred group of metals from which the additive can be selected includes aluminum, chromium, cobalt, iron, manganese, magnesium, nickel, vanadium, and zinc.The use of these additives allows the production of coatings with low levels of haze. Preferred group of metals from which the additive can be selected includes aluminum, chromium, cobalt, iron, magnesium and zinc.These additives have the most favorable effect on the reflectance of the product.Therefore, to form a coating with high reflectivity and under cloudiness, the additive is preferably selected from aluminum, chromium, cobalt, iron, magnesium and zinc, more preferably between chromium, iron and magnesium.Chrome is the most preferred, since it allows to achieve a product with high reflectance and very low turbidity , and which may have a neutral aspect in reflection, as described and claimed in our co-pending patent application of the same date that the present application, the reflectance of the coating can be further improved by the application of an outer reflective layer with a geometric thickness in the area of 30 to 150 nm and a refractive index in the area from 2.0 to 2.8. The application of a pyrolytic coating on a flat glass can be carried out optimally when the glass is newly formed, for example when it leaves the float glass production line. This provides economic benefits since it avoids the need to reheat the glass to produce the pyrolytic reactions, and also benefits in the quality of the coating, since the surface of the newly formed glass is in pristine conditions. Preferably the tin source is selected from one or both of SnCl 4 and monobutyl trichlorotin ("MBTC"). The source of antimony can be selected from one or more of SbCl6, SbCl3, organic antimony compounds such as Sb (OCH2CH3) 3, Cl1 7Sb (CH2CH3) ± .3, Cl2SbOCHClCh3, Cl2SbOCH2CHCH3 Cl and Cl2SbOCH2C (CH3) 2Cl. Similarly, the source of the additive may be a suitable chloride or organometallic compound of the respective element. The tin, antimony and additive sources are preferably formed in a single initial solution, described herein as a "reactant mixture" so that it can be applied to the substrate simultaneously. The mixture of reagents can be applied to the substrate by chemical vapor deposition (CVD or "vapor pyrolysis") or as a liquid spray ("liquid pyrolysis"). Especially for liquid spray deposition, the proportions of tin, antimony and additive in the formed coating can differ significantly from those of the mixed solution. reagents, so that it may be necessary to alter the relative concentrations of reagents to obtain layers having the desired proportions in the coating. In the reagent mixture, the proportion of tin is typically between 20 and 45% by weight in the region and the proportion of antimony is typically between 0.5 and 2.5% by weight of the total mixture. . The proportion of additive is preferably comprised in the zone between 0.2 and 3.6% by weight. Due to the difficulty in establishing the proportion of additive in the finished coating, the amount of additive to be used is determined in the step of forming the reagent mixture. To form the modified tin oxide / antimony coating by CVD, the substrate is contacted, in a coating chamber, with the reagent mixture which includes the tin, antimony and additive sources. The reagent mixture is typically delivered through a first nozzle. When this mixture includes chlorides, which are liquid at room temperature, it is vaporized in a heated stream of an anhydrous carrier gas, such as nitrogen. Vaporization is facilitated by the atomization of these reagents in the carrier gas. To produce the oxides, the chlorides are placed in the presence of water vapor supplied through a second nozzle. The methods and devices for forming said coating are described, for example, in French patent Nr. 2348166 or in French patent application Nr. 2 648 453 Al.

These methods and devices lead to the formation of particularly resistant coatings with advantageous optical properties. To form the coating by the spraying process, the substrate can be contacted with a spray of drops containing the tin, antimony and additive sources. The spray is applied by means of one or more spray nozzles arranged to follow a path that provides the coating across the width of the band to be coated. The CVD process offers the benefit over the sprayed liquids of providing coatings of regular thickness and composition, said uniformity of the coating being important when the product must cover a large area. A spray coating also tends to retain traces of the sprayed drops and the passage of the spray gun. further, the pyrolysis of sprayed liquids is essentially limited to the manufacture of oxide coatings, such as Sn02 and Ti02. It is also difficult to make multiple layer coatings using sprayed liquids, because each coating deposition causes significant cooling of the substrate, and the CVD process is more economical in terms of raw materials, resulting in less waste. in spite of such disadvantages of the spraying process, the application thereof is convenient and inexpensive, using simple equipment, which is therefore often adopted, especially for the formation of thick layers of coating. If desired, an intermediate coating layer can be placed between the substrate and the modified tin oxide / antimony coating layer, as a "base coat layer" for the modified layer, to adjust the optical properties of the coating. For example, it has been found that in the pyrolytic deposition of a tin oxide coating of tin chloride on a calcium glass sodium substrate, sodium chloride tends to be incorporated into the coating as a result of the reaction of the glass with the material precursor of the coating or its reaction products, which leads to a clouding of the coating. The presence of a base coat layer can reduce or eliminate such clouding. An effect of said base coat layer is to inhibit the migration of sodium ions from a calcium sodium glass substrate, either by diffusion or otherwise, to the modified tin oxide / antimony coating. Said diffusion may occur during the formation of the coating or during a subsequent treatment at high temperature. It has also been noted that for a tin oxide / antimony coating a selected base coat layer can give a more neutral dye in reflection, which is considered as an improvement in the aesthetic attractiveness of the coating. In a "embodiment of the present invention, the basecoat layer can be pyrolytically formed in a state not completely oxidized by contacting the substrate in a basecoat layer coating chamber with the precursor material of the basecoat layer in the presence of oxygen in insufficient quantity for complete oxidation of the basecoat layer material in the substrate. The term "not completely oxidized material" is used herein to denote a real sub-oxide, that is, an oxide with a lower valence state of a multivalent element (for example V02 or UNCLE), and also to denote an oxide material that contains rests of oxygen in its structure: an example of this last material is SiOx, where x is less than 2, which can present the general structure of Si02 but has a proportion of gaps that would be occupied with oxygen in the dioxide. A preferred example of material for the basecoat layer is alumina with a small proportion of vanadium oxide. Said alumina / vanadium material is described in GB 2248243. The preferred geometric thickness of a base coat layer of this material is between 40 and 100 nm, for example around 80 nm. If a vitreous substrate with a non-completely oxidized coating is exposed to an oxidizing atmosphere for a sufficiently long period, it can be expected that the coating tends to oxidize completely, so that its desired properties are lost. In "consequence, said base coat layer is overcoated with the modified tin oxide / antimony coating layer while it is still in the not fully oxidized state, and while the substrate is still hot, preserving said coating layer. base in a state not completely oxidized. The time during which said vitreous substrate can be exposed with the basecoat layer recently applied to an oxidizing atmosphere such as air, and before said basecoat layer is overcoated, "without" affecting the properties of The basecoat layer will depend on the temperature of the glass during said exposure and the nature of the basecoat layer. Advantageously, said base coat layer application chamber is surrounded by a reducing atmosphere. This prevents environmental oxygen from entering the chamber, thus allowing better control of oxidation conditions. The oxygen required for the reaction of the basecoat layer does not need to be pure oxygen and can therefore be provided by a controlled source of air. Glazed panels incorporating coated substrates according to the invention can be manufactured as follows. Each pyrolytic coating step can be carried out at a temperature of at least 400 ° C, ideally from 550 ° C to 750 ° C. The "coatings can be formed on a glass sheet that is moved in a furnace tunnel or on a glass ribbon during the formation, while it is still hot. The coatings may be formed within the annealing tunnel disposed next to the glass ribbon forming device or within the flotation tank on the upper face of the glass ribbon while it is floating on a molten tin bath.

The invention will be described below in greater detail, with reference to the following non-limiting examples. In the Examples, the molar ratio Sb / Sn in the basecoat layers was determined by an X-ray analysis technique, in which the amount of X-ray counting of the respective elements was compared. Although this technique is not as precise as conducting a calibration by chemical dosage, the similarity of antimony and tin means that they respond in a similar way to X-rays. Consequently, the ratio of the measured quantity of observed computations of the respective elements provide a close approximation to their molar relationship. - The initials of the headings in the attached tables (TL, TE, etc.) have the meanings described above.

Examples 1 to 13 A coating was applied to a 6-mm thick clear sodium calcium glass in a "coating station located at a position in a flotation chamber where the glass was at a temperature above 550 ° C. Reagent mixing solution including monobutyltrichlorotin ("MBTC"), Cl1 7Sb (OCH2CH3) 1 3, a chromium precursor and 4% by weight of a methylisobutyl ketone C4H9COCH3 stabilizer was sprayed onto the glass through a spray head of alternate displacement to form a coating that includes an oxidized mixture of tin, antimony and chromium The proportions of Sn, Sb and Cr in said solution were respectively, 37.35%, 0.783% and 0.5% by weight, ie a Sb / Sn ratio in the solution of 0.02. The attached Table 1 illustrates the thickness of the resulting coated substrate and its Sb / Sn ratio, together with its reflectance and other optical properties. For the other examples, the procedure of Example 1 was followed but with variations in the choice of the additives and their proportions in the reagent mixture, as indicated in Table 77 below The proportions of the respective components were expressed as percentages Weight of the total mixture It should be taken into account that the comparisons of the respective reflectance values between the different examples can only be made for thicknesses and similar Sb / Sn ratios, since these parameters are of great importance for the reflectance value For example, two coatings of the same composition will show differences in reflectance as a function of their thicknesses Examples 1 to 4 illustrate that chromium as an additive gives a coating with less haze and with increased reflectance. but it is * very low if a base coat layer of Si02 is deposited between the glass and the coating (see example 4). Examples with Fe and examples with Mg as an additive show high values of reflectance.

TABLE 1 '' The solution also contains 0.1% Ti to improve the stability of the nickel compound TABLE 2 Example 14: A reagent mixing solution including monobutyltrichlorotin ("MBTC"), SbCl3, a vanadium precursor (vanadium triacetylacetonate) and 4% by weight of a stabilizer (methyl isobutyl ketone C4 H2 C0CH3) was sprayed onto the glass by an alternate displacement spraying head to form a coating including an oxidized mixture of tin, antimony and vanadium. The Sb / Sn ratio in the solution was 0.07. The refI / Rancia value obtained for this example was low.

/ Examples 15 and 16: The procedure of Example 1 was followed but without variations in the choice of the additives and their proportion in the reagent mixture. The additive was zirconium. These examples showed good reflectance but with high turbidity, even with a base coat.

Examples 17 to 27: A base coat was applied to a 6-mm thick calcium-float sodium glass in a coating station located at a position in a flotation chamber, in which the glass was at a temperature above 550 ° C. A glacial acetic acid solution of 220 g / 1 aluminum acetylacetonate and 12 g / 1 of vanadium tricyethylacetonate was sprayed onto the glass by an alternate displacement spray head to form a base coat of about 80 nm in thickness, which it included an oxidized mixture of aluminum and vanadium. The glass substrate thus coated was passed to a second coating station in which the glass was sprayed with a reagent mixing solution that included monobutyltrichlorotin ("MBTC"), Cl12Sb (OCH2CH3) 1 3, and a precursor additive by an alternate displacement spraying head to form a coating with an oxidized mixture of tin, antimony and aluminum. The additive proportions and the Sb / Sn ratio in said solution were as mentioned in the following table 3, which also indicates the thickness of the resulting coated substrate and its Sb / Sn ratio, together with its reflectance and other optical properties.

Examples 28 to 33: Coated glass substrates prepared as in Examples 17 and 18 were formed "on double glazed panels that included the coated substrate and a similar sheet but of uncoated calcium glass sodium.The reflectance and other optical properties of the panels thus shaped "are illustrated in the accompanying Table 4. The position of the coating is indicated by the designations Pl, P2 or P3, where Pl represents the facing surface towards the outside of the outer sheet, P2 represents the facing surface towards the inside of the outer sheet, and P3 represents the facing surface toward the outside of the inner leaf. The results of Examples 17 and 18 (with a monolithic sheet) are repeated in Table 3 for- "an easier comparison with the double glazed panels.

TABLE 3 TABLE 4 0 CS = Coated side

Claims (36)

1. CLAIMS 1. - Transparent substrate with a pyrolytically formed coating layer including tin and antimony oxides in a Sb / Sn molar ratio of 0.01 to 0.5, characterized in that the coating layer also contains an additive selected from the group which comprises aluminum, chromium, cobalt, iron, manganese, magnesium, nickel, vanadium, zinc and zirconium, and which is also free of fluorine, whereby the substrate thus coated has a reflectance (RL) of at least 10%.
2. 2. Transparent coated substrate according to claim 1, characterized in that the molar ratio Sb / Sn in said coating layer is comprised in the area between 0.03 and 0.21.
3. 3. Transparent coated substrate according to claim 2, characterized in that the molar ratio Sb / Sn is comprised in the area between 0.03 and 0.16.
4. 4. - Coated transparent substrate according to any of the preceding claims, characterized in that the additive is selected from the group comprising aluminum, chromium, cobalt, iron, manganese, magnesium, nickel, vanadium and zinc.
5. 5. - Coated transparent substrate according to any of claims 1 to 3, characterized in that the additive is selected from the group comprising aluminum, chromium, cobalt, iron, magnesium and zinc.
6. 6. - Coated transparent substrate according to any of the preceding claims, characterized in that the additive is selected from the group comprising chromium, iron and magnesium.
7. 7. - Transparent coated substrate according to any of the preceding claims, characterized in that the reflectance
8. (RL) is at least 13%. 8. - Coated transparent substrate according to any of the preceding claims, characterized in that said coating layer has a thickness comprised between 100 and 500 nm.
9. 9. "Transparent coated substrate according to any of the preceding claims, characterized in that the tin source for said coating layer is selected from SnCl 4 or monobutyl trichlorotin (" MBTC ").
10. 10. - Transparent coated substrate according to any of the preceding claims, characterized in that the source of antimony for said coating layer is selected from the group comprising SbCl5, SbCl3, organic antimony compounds such as Sb (OCH2CH3) 3, Cl1.7Sb (CH2CH3) 1 3, Cl2SbOCHClCh3, Cl2SbOCH2CHCH3 Cl and Cl2SbOCH2C (CH3) 2C1
11. 11.- Coated transparent substrate according to any of the preceding claims, characterized in that the source of the additive for said coating layer is selected from a chloride or organic compound. of the respective element
12. 12. - Coated transparent substrate according to any of the preceding claims, characterized in that it also includes a cover layer ^ base located between the substrate and said cover layer
13. 13. - Coated transparent substrate according to claim 9, characterized in that said basecoat layer includes alumina with a small prop vanadium oxide.
14. 14. - Transparent coated substrate according to the claim 13, characterized in that the geometrical thickness of the base coat layer is between 40 and 100 nm.
15. 15. - Coated transparent substrate according to any of claims 12 to 14, characterized in that the base coat layer gives the coating a more neutral reflection dye.
16. 16. Coated transparent substrate according to any of the preceding claims, characterized in that the solar factor (FS) is at most 70%, optionally at most 65%.
17. 17. Transparent coated substrate according to any of the preceding claims, characterized in that it has a light transmittance (TL) comprised between 35 and 76%.
18. 18. - Glazed panel comprising a transparent substrate coated according to any of the preceding claims.
19. 19. Glazed panel according to claim 18, characterized in that it comprises two or more sheets of substrate, of which one is a transparent coated substrate according to any of claims 1 to 17.
20. 20. Glazed panel according to claim 18 or claim 19, to be used as a glazed panel in buildings .
21. 21. Glazed panel according to claim 18 or claim 19, for use in a vehicle window.
22. 22. - Glazed panel according to any of claims 18 to 21, characterized in that the coating according to the invention is located facing the exterior of the building or vehicle.
23. 23. Glazed panel according to claim 19, characterized in that the coating according to the invention is located on the outer face of the outer leaf.
24. 24. - Process for forming a coated transparent substrate, which comprises the pyrolytic deposition of a mixture of reagents on the substrate of a coating layer containing tin oxide and antimony in a molar ratio Sb / Sn comprised between 0.01 and 0.5, said reagent mixture including a source of tin and a source of antimony, characterized in that the reagent mixture also contains an additive selected from the group including aluminum, chromium, cobalt, iron, manganese, magnesium, nickel, vanadium. , zinc and zirconium, and which is also free of fluorine, said substrate thus coated having a reflectance (RL) of at least 10%.
25. 25. - Process according to claim 24, characterized in that the coating layer is applied by one or more pyrolytic coating steps at a temperature of at least 400 ° C.
26. 26. - Method according to claim 25, characterized in that the temperature is comprised in the zone between 550 ° C to 750 ° C.
27. 27. Method according to claim 25 or 26, characterized in that the coating layer is formed on a glass sheet in a furnace tunnel or on a glass ribbon during the formation, while it is still hot.
28. 28. Method according to any of claims 24 to 27, characterized in that the tin source is selected from one or both of SnCl4 and monobutyl trichlorotin ("MBTC").
29. 29. - Method according to any of the claims 24 to 28, characterized in that the source of antimony is selected from the group comprising SbCl5, SbC13, organic antimony compounds such as Sb (OCH2CH3) 3, Clx 7Sb (CH2CH3) 3, Cl2SbOCHClCh3, Cl2SbOCH2CHCH3 Cl and Cl2SbOCH2C (CH3) 2C1.
30. 30. Method according to any of claims 24 to 29, characterized in that the tin, antimony and additive sources are formed in a single mixture of reagents, so as to "apply it to the substrate simultaneously."
31. 31.- Procedure according to the claim 30, characterized in that said mixture is applied to the substrate by chemical vapor deposition (CVD)
32. 32. Method according to claim 30, characterized in that said mixture is applied to the substrate as a liquid spray
33. 33. - Method according to any of the claims 24 A 32, characterized in that a base coat layer is formed between the substrate and said coating layer
34. 34. Method according to claim 33, characterized in that said base coat layer is pyrolytically formed in a state not completely oxidized by contacting the substrate in a base coating chamber with a precursor coating material ba oxygen is present in insufficient quantity to cause complete oxidation of the basecoating material on the substrate.
35. 35.- Method according to claim 33, characterized in that the base coat layer is alumina with a small proportion of vanadium oxide.
36. 36.- Method according to any of claims 33 to 35, characterized in that the geometrical thickness of the base coating is comprised in the zone between 40 and 100 nm.