Title of Invention	SOLAR-PROTECTION GLAZING HAVING AN IMPROVED LIGHT TRANSMISSION COEFFICIENT
Abstract	The subject of the invention is a transparent glass substrate comprising at least one glass sheet provided with a thin-film multilayer coating acting on solar radiation, having a light transmission of greater than 10% and an emissivity of less than 50% after a heat treatment, such as a bending or toughening treatment, characterized in that said multilayer coating comprises: - a niobium Nb functional layer with a thickness of between about 5 nm and about 35 nm; and - at least one layer of another material, chosen from the group formed by Ti, Mo, B, Al or an alloy comprising at least one of these elements, which is placed relative to the glass substrate above the functional layer, said layer having a thickness of between about 1 nm and about 5 nm. The invention also relates to monolithic glazing or double glazing incorporating such a substrate.

Title of Invention

SOLAR-PROTECTION GLAZING HAVING AN IMPROVED LIGHT TRANSMISSION COEFFICIENT

Abstract

The subject of the invention is a transparent glass substrate comprising at least one glass sheet provided with a thin-film multilayer coating acting on solar radiation, having a light transmission of greater than 10% and an emissivity of less than 50% after a heat treatment, such as a bending or toughening treatment, characterized in that said multilayer coating comprises: - a niobium Nb functional layer with a thickness of between about 5 nm and about 35 nm; and - at least one layer of another material, chosen from the group formed by Ti, Mo, B, Al or an alloy comprising at least one of these elements, which is placed relative to the glass substrate above the functional layer, said layer having a thickness of between about 1 nm and about 5 nm. The invention also relates to monolithic glazing or double glazing incorporating such a substrate.

Full Text	SOLAR-PROTECTION GLAZING HAVING AN IMPROVED LIGHT TRANSMISSION COEFFICIENT The invention relates to glazing provided with thin- film multilayer coatings, one of the layers of which is a functional layer, that is to say it acts on solar radiation. The present invention relates more particularly to multilayer-coated glazing, especially that intended for thermal insulation and/or solar protection. The term "functional" layer is understood within the context of the present invention to mean the layer or layers of the multilayer coating that give the latter most of its thermal properties, as opposed to the other layers, which are generally made of a dielectric material and have the function of chemically or mechanically protecting said functional layers, or else another function, for example an optical function, adhesion function, etc. The solar-protection glazing according to the invention is . more particularly suitable for fitting into buildings: by limiting the amount of solar radiation energy transmitted, thanks to the thin layers, such glazing prevents the interior of rooms from being excessively heated in the summer and thus helps to limit the consumption of energy needed for air- conditioning them. The invention also relates to this type of glazing once it has been covered with said thin layers, in order to obtain a wall cladding panel, called more conventionally "curtain walling", which makes it possible, in combination with window glazing, to provide buildings . with exterior surfaces that are entirely glazed. Solar-protection functional multilayer-coated glazing is subject to a number of constraints: firstly, the layers employed must filter out the solar radiation sufficiently, and especially the non-visible part of the solar, radiation lying between about 780 nm and 2500 nm, usually called solar infrared (or solar IR) . Furthermore, this thermal performance must preserve the optical and aesthetic appearance of the glazing: in particular, it is desirable to be able to modulate the level of light transmission (TL) of the substrate. According to another important aspect, the functional layers must be sufficiently durable and, in particular, physically resistant, such as scratch 'resistant, and chemically resistant - they must in particular be moisture resistant. This is all the more important if, in the glazing once fitted, said functional layers are on one of the exterior faces of the glazing (as opposed to the "interior" faces turned towards the intermediate gas-filled, cavity of for example a double-glazing unit) or if the glazing is single glazing, i.e. comprising only a single glass sheet. There is another constraint that arises during the production of the glazing: when the latter consists at least partly of glass substrates, these usually have to undergo one or more heat treatments, which may be a bending operation if it is desired to shape them (to form a shop window), but which is often a toughening or annea'ling operation, especially in the building sector in which it is desired for the glazing to be more resistant and less hazardous in the event of impacts. The fact that the layers are deposited on the glass before its heat treatment frequently means that they are damaged and their properties, especially optical properties, are substantially modified. However, depositing the layers after the heat treatment of the glass proves to be complex and expensive. An example of solar-protection glazing for buildings is given in patents EP-0 511 901 and EP-0 678 483: these refer to functional layers for filtering out solar radiation which are made of a nickel-chromium alloy, optionally nitrided, made of stainless steel or of tantalum, and which are placed between two dielectric layers of metal oxide such as SnO2, TiO2 or Ta2O5. Such glazing provides good solar protection, with satisfactory mechanical and chemical durability, but it is not truly "bendable" or "toughenable" within the meaning • described above, since the oxide layers surrounding the functional layer do not prevent it from being oxidized during the bending or toughening operation, said oxidation being accompanied by a substantial modification in the light transmission and in the general appearance of the glazing in its entirety. More recently Patent Application EP 1 218 307 has proposed a solar-protection multilayer coating, the functional layer of which comprises an optionally nitrided metal chosen from Nb, Ta and Zr, the functional layer being surmounted by protective layers based on aluminium, nitride or oxynitride or on silicon nitride or oxynitride. The multilayer coating according to . th'is application gives the glazing a solar- protection function enabling it to block out the solar IR of the incident solar radiation. Furthermore, this multilayer coating, proves to be resistant to the toughening operation and mechanically and chemically durable sufficiently to be used as face 2 of single glazing.However, the major drawback of the multilayer coating described in EP 1 218 307 is that the functional layer is relatively thick, so as to obtain the desired solar-protection effect, and consequently has a very low TL, Of the order of 10%, or even less. The object of the invention is thus to substantially increase the light transmission TL of such solar- protection glazing, without thereby such an increase leading to an appreciable reduction in the thermal insulation properties of the glazing, which could result in excessive heat transfer between the interior and the exterior of the building or of the passenger compartment protected by said glazing. Glazing capable of meeting such an application is known in the field. Such glazing is coated with one or more thin functional layers of metallic silver Ag. Such glazing is for example described in the Patent Application EP 718 250. It is well known that incorporating one or more silver layers into the glazing enables the heat transfer through the glazing to be very greatly reduced, because of, the low emissivity of the Ag layers, i.e. their ability to reflect most of the thermal IR lying between 3 and 50 microns. It is then possible to obtain, using well- known techniques and especially the addition of dielectric interference layers of suitable index and thickness, glazing that has a high light transmission but the heat transfer coefficient of which nevertheless remains very low. The solar-protection layers based on thin silver films thus appear to be very efficient in respect of thermal insulation but their mechanical and chemical durability is very limited, in particular when in contact with a wet atmosphere, and in particular prevents them from being used for single glazing. Furthermore, this solution is relatively expensive to implement in the case of double glazing. The invention therefore consists in the development of novel thin-film multilayer coatings that act on solar radiation, with a view to manufacturing improved solar- protection glazing. The intended improvement is in particular the establishment of a better compromise between durability, thermal properties, optical properties and solar-protection function, in particular light transmission, and capability of withstanding heat treatment without being damaged when the substrate bearing the multilayer coating is of the glass type. 'More precisely, the object of the present invention is therefore to provide glazing coated with thin layers that give it good solar-protection properties and a light transmission equal to or greater than 10% or even 20%, but however still having an acceptable heat transfer coefficient, thanks in particular to a sufficiently low emissivity coefficient α, as defined according to the European standard prEN 410, said multilayer-doated glazing also being able to undergo a heat treatment as explained above. According to the- invention, such single or multiple glazing has been able to be obtained that has in particular: a light transmission equal to or greater than 10% or greater than 20%, or even 30% or 40%; - an emissivity equal to or less than 50%, preferably,less than 40% or less than 30% or even 20%; resistance to heat treatment such as a bending or toughening operation, especially with the above properties being maintained, and chemical resistance, as described above; and good chemical and mechanical durability. The subject of the invention thus firstly consists of a transparent glass substrate comprising at least one glass sheet provided with a thin-film multilayer eoating acting on solar radiation, having a light transmission equal to or greater than 10% or even greater than 20% and an emissivity equal to or less than 50%, or less than 40%, or even less than 30% or 20% after a heat treatment, such as a bending or toughening treatment, said multilayer coating comprising: a functional layer based on niobium Nb with a thickness of between about 5 nm and about 35 nm; and at least one layer of another material, chosen from the group formed by Ti, Mo, B, Al or an alloy comprising at least one of these elements, which is placed relative to the glass substrate above the functional . layer, said layer having a thickness of between about 1 nm and about 5 nm. According to a possible embodiment, the transparent glass substrate comprises . at least one glass sheet provided with a thin-film multilayer coating acting on solar radiation, having a light transmission equal to or greater than 20% and an emissivity equal to or less than 50%. after a heat treatment, such as a bending or toughening treatment, said multilayer coating comprising: a functional layer based on niobium Nb with a thickness of between about 5 nm and about 25 nm; and at least one layer of another material, chosen from the group formed by Ti, Mo, B, Al or an alloy comprising at least one of these elements, which is placed relative to the glass substrate above the functional layer, said layer having a thickness of between about 1 nm and about 5 nm. Preferably, a layer of said material chosen from the group formed by Ti, Mo, B, Al is placed above the functional layer and another layer of said material is placed beneath the functional layer. Typically, the functional layer based on niobium Nb has a thickness of between 8 nm and about 20 nm, for example of between 8 nm and 15 nm. Typically, the layer of material chosen from the group formed by Ti, Mo, B, Al has a thickness of between about 1 nm and about 3 nm. Preferably; said material is Ti. According to the invention, the combination of the functional layer and of the layer or layers of said material is surrounded by at least one additional layer based on aluminium nitride, aluminium oxynitride, silicon nitride or silicon oxynitride, or based on a mixture of at least two of these compounds, the thickness of said additional layer- or layers being adju'sted in order to optimize the light transmission of the glazing. For example, said additional layer or layers are based on silicon nitride, and are placed above and below said combination respectively. According to one possible embodiment, the layer based on silicon nitride placed above said combination is thicker than the layer placed beneath the combination by at least a factor of 1.2, especially at least a factor of 1.5 to 1.8. The invention also relates to monolithic glazing or double glazing incorporating the substrate as described above, the multilayer coating of thin layers being placed on face 2 of the monolithic glazing or of the double glazing, or on face 3 of the double glazing, the faces of the substrate or substrates being numbered from the exterior to the interior of the building or of the passenger compartment that it equips. According to one embodiment, the monolithic glazing or double glazing is configured to have a light transmission TL of , greater than 10%, 20% or, even 30%, or even greater than 40%. The monolithic glazing or double glazing may also be configured to have an emissivity of less than 40%, or less than 30% or even less than 20%. Finally, the present invention relates to a wall cladding panel of the curtain-walling type, incorporating at least one substrate as described above or to a side window, rear window or sunroof for an automobile, or another vehicle, formed by or incorporating said substrate. According to the invention, the functional layers of the invention make it possible for the substrate to have a relatively high light transmission, while still maintaining an appreciable solar-protection effect, despite the relatively small thickness of the functional layer: the measurements made show in fact a good compromise between the level of light transmission TL and the heat transfer coefficient U of the multilayer-coated substrate, as measured by its emissivity a. In the present description, the emissivity is a normal emissivity as de'fined according to the standard prEN 410. The use of a very thin layer of a metal of the group Ti, Mo, B, Al, in particular Ti, makes it possible according to the invention to guarantee the toughenability of the multilayer coating without an accompanying degradation in the functional properties thereof. In particular, the change in optical properties, especially the light transmission, caused by a toughening heat treatment, is low. Likewise, the emissivity of the functional layer remains low thanks to the addition of this additional thin metal layer. According to one possible embodiment of the invention, the thin layer of metal of the group Ti, Mo, B, Al is deposited at least on top of the Nb functional layer. Preferably, said layer is deposited on top of and beneath the Nb layer. In the present description, the terms "on top of" and "beneath" refer to the respective position of said layers relative to the glass substrate supporting the multilayer coating comprising said layers. According to one embodiment of the invention, it is preferable to deposit also an overlayer based on silicon or aluminium nitride (Si3N4 and A1N) or based on silicon or aluminium oxynitride (SiON and A1N0 in short, without judging the respective quantities of Si, O and N) . The thickness of such layers is adjusted so as to obtain an antireflection effect enabling the light transmission of the multilayer-coated glazing to be optimized. Such layers may also play, to a lesser extent, a role of protecting the functional layers of the invention. Without departing from the scope of the invention, it is also possible according to the invention to dope these layers with elements such as Zr, B, etc., so as to modify the colour of the glazing in transmission and/or in reflection, in accordance with the well-known techniques in the field. Preferably, the multilayer coating according to . the invention comprises, between the substrate and the functional layer, at least one underlayer made of a transparent dielectric, especially chosen, as in the case of. the overlayer, to be silicon nitride or oxynitride and/or aluminium nitride or oxynitride, or else; silicon oxide SiO2. In particular, its presence may make it possible for the optical appearance conferred on the carrier substrate by its multilayer coating to be varied more flexibly. Furthermore, in the case of heat treatment, said underlayer may constitute an additional barrier, in particular to oxygen and to alkali metals from the glass substrate, which species are liable to migrate due to the heat and degrade , the multilayer coating. A very preferred variant of the invention may for example consist in using both an overlayer and an underlayer based on silicon nitride. The thickness of the overlayer is preferably between 5 and 70 nm, especially between 40 and 60 nm. The thickness of the optional underlayer is preferably between 5 and 120 nm. When there is a single underlayer of the Si3N4 type, its thickness is for example between 30 and 50 nm. the underlayer and/or the overlayer may in fact form part of a superposition of dielectric layers. One or other layer may thus be combined with other layers of different refractive indices. Thus, the multilayer coating may comprise, between the substrate and the functional layer (or on top of the functional layer) an alternation of three, high index/low index/high index, layers, the "high index" layer (having an index of at least 1.8 to 2) or one of said layers possibly being the sublayer of the invention of the Si3N4 or A1N type and the "low index" layer (for example of index less than 1.7.) possibly being made of silicon oxide SiO2. More particularly, a very preferred embodiment of the invention consists of single or multiple glazing comprising a substrate on which is deposited a multilayer coating comprising a functional layer based on niobium with a Ti layer on either side thereof, the combination of the Ti/Nb/Ti layers itself being surmounted by an overlayer based on silicon nitride and by an underlayer also based on silicon nitride. The subject of the invention applies both to single or "monolithic" glazing, i.e.. consisting of a single substrate, and insulating multiple glazing of the double-glazing type. Preferably, whether in monolithic glazing or double glazing, the multilayer coatings are placed on face' 2 (conventionally, the faces of the panes/substrates of glazing are numbered from the outside to the inside of the passenger compartment/room equipped therewith) and protect against solar radiation. Without departing from the scope of the invention, the multilayer coatings may also be deposited on face 3 of double glazing. Another subject of the invention is a multilayer-coated substrate at least partially opacified by covering of the lacquer or enamel type, with the purpose of producing curtail walling, where the opacifying covering is in direct contact with the multilayer coating. The multilayer coating may therefore be exactly the same both for window glazing and for curtain walling. Although the application more particularly intended by the invention is architectural glazing, it is clear that other applications can be envisaged, especially automotive glazing (apart from windscreens, which require a very high light transmission) , such as the side windows, sunroof and rear window. The invention and its advantages will be described in greater detail below by means of. the following non- limiting examples according to the invention and comparative examples. In all the examples and the description, the thicknesses are geometric thicknesses. All the substrates are made of clear glass 6 mm in thickness of the Planilux type sold by Saint-Gobain Vitrage. All the layers were deposited in a known manner by magnetron sputtering. The metal (Nb, Ti) layers were deposited from metal targets in an inert atmosphere (100%- Ar) , the silicon nitride Si3N4 layers were deposited from a suitable silicon target (the silicon being doped with 8% aluminium by weight) in a reactive atmosphere containing nitrogen (40% Ar/60% N2) . The Si3N4 layers therefore contain a little aluminium. EXAMPLE 1 (according to EP 1 218 307) This example has an Nb functional layer, an Si3N4 underlayer and an Si3N4 overlayer according to the following sequence: glass/Si3N4 (10 nm)/Nb' (35 nm)/Si3N4 (30 nm) . After the layers had been deposited, the substrate underwent the following heat treatment: heating at 620°C for 10 minutes followed by quenching. . EXAMPLE 2 (comparative example) In this example, the same functional layer and the other layers as in Example 1 were used, these being deposited on the same substrate but with modifications in the thicknesses of the Si3N4 underlayer and overlayer: glass/Si3N4 (40 nm)/Nb (10 nm)/Si3N4 (60 nm) . The substrate coated with the multilayer coating then underwent the same heat treatment as described in Example 1. EXAMPLE 3 (according to the invention) This example uses the same sequence of layers as in Example- 2, deposited on the same substrate, but with a very thin metallic titanium layer deposited on top of the functional layer. The multilayer coating thus comprises the following succession of layers: glass/Si3N4 (40 nm)/Nb (10 nm)/Ti (about 1 nm)/Si3N4 (60 nm) . The substrate coated with the multilayer coating then underwent the same heat treatment as described in Example 1 or Example 2. EXAMPLE 4 (comparative example) This example uses the same sequence of layers as in Example 2, deposited on the same substrate, but a very thin metallic titanium layer is deposited beneath the functional layer. The multilayer coating thus comprises the following succession of layers: glass/Si3N4 (40 nm) /Ti (about 1 nm)/Nb (-10 run) /Si3N4 (60 nm) . The -substrate coated with the multilayer coating then undergoes the same heat treatment as described in Example 1 or 2. EXAMPLE 5 (according to the invention) This example uses the same sequence of layers as in Example 2, deposited oh the same substrate, but a very thin titanium metal, layer is deposited on top of and beneath the functional layer. The multilayer coating thus comprises the following succession of layers: glass/Si3N4 (40 nm)/Ti (≈ 1 nm) /Nb (10 nm)/Ti (≈ 1 nm) /Si3N4 (60 nm) . The substrate coated with the multilayer coating then underwent . the same heat treatment as described in 'Example 1 or 2. EXAMPLE 5b (according to the invention) This example uses the, same sequence of layers as in Example 2, deposited on the same substrate. The multilayer coating thus comprises the following succession of layers.: glass/Si3N4 (40 nm)/Ti (≈ 1 nm)/Nb (19 nm)/Ti (≈ 1 nm) /Si3N4 (50 nm). The substrate coated with the multilayer coating then underwent the same heat treatment as described in Example 1 or 2. EXAMPLE 6 (comparative example) This example used the same sequence of layers as in Example 2, deposited on the same substrate, but a very thin NiCr layer is deposited on top of and beneath the functional layer. The multilayer coating thus comprises the following succession of layers: glass/Si3N4 (40 nm) /NiCr (≈1 nm) /Nb (10 ran) /NiCr (≈1 nm) / Si3N4 (60 nm). The substrate coated with the multilayer coating then underwent the same heat treatment as described in Example 1 or 2. Table 1 below gives the measured optical transmission TL values (the light transmission being in % under illuminant D65) and the emissivity a values, which are calculated according to the prEN 410 and NFEN 673 standards, for Examples 1 to 6 above. The values are given twice, once before heat treatment and once after heat treatment. In the table 1, the relative rise Aa of the emissivity a value, after the quenching; is reported in percentage. The values given in Table 1 show that Examples 3, 5. and 5b according to the invention provide a much higher light transmission than the solar-protection glazing of the prior art, while still maintaining acceptable energy performance, after the heat treatment and toughening operation. The comparison of the emissivity values obtained after toughening for Example 4 with the values obtained for Examples 3, 5 and 5b show that the best compromises are obtained when a Ti metal layer is deposited at least on top of the Nb functional layer. The results obtained for Example 2, which is not according to the present invention (since the multilayer coating is not provided with one or more Ti metal layers), are much inferior after the toughening operation. These multilayer coatings are clearly not bend-able/ toughenable within the meaning of the invention. The heat treatment significantly degrades the thermal insulation properties: the emissivity values of such glazing thus appear to be much too high. The results obtained according to Example 6, in which the metal layer deposited on the functional layer is this time made of NiCr, are similar to those obtained for Example .2, i.e. in the absence of a layer. EXAMPLE 7 (according to the invention) For this example, a multiple glazing unit was constructed from the substrate of Example 5 (after the toughening operation). The multiple glazing unit was assembled according to the conventional techniques in a 6/12/6clear (100% air) configuration, i.e. in such a way that it is made up of two clear glass sheets 6 mm in thickness separated by a 12 mm thick air space. The multilayer coating was deposited on face 2 of the double glazing unit. The double glazing unit has a light transmission of 36% but a relatively low emissivity, about 37%, enabling most of the thermal IR radiation to be reflected. The energy insulation performance is thus very satisfactory, the heat transfer coefficient U having been measured to be 2.30 W.m-2.K-1. For comparison, the coefficient U is equal to 2.90 W.m-2.K-1 for a simple, i.e. not multilayer-coated, double glazing unit. Again for comparison, the low-E transparent glazing of the prior art, incorporating as functional layer a not easily toughenable silver layer, has a coefficient of around 1.8 W.m-2.K-1, but are very much less, durable, both in terms of chemical resistance and mechanical resistance. EXAMPLE 8 (according to the invention) In this example, the aim was to obtain a multiple glazing unit based on a substrate in which the layers of the multilayer coating have thicknesses suitable this time for maximizing the energy performance of the glazing. The . multilayer coating thus comprises the following succession of layers: glass/Si3N4 (40 nm) /Ti (≈ 1 nm)/Nb (20 nm) /Ti .(≈ 1 nm) /Si3N4 (54 nm) . The substrate coated with the multilayer coating then underwent the same heat treatment as described above. A multiple glazing unit was then manufactured from this substrate. In a manner similar to Example 7, the multiple glazing unit was assembled in a 6/12/6clear (100% air) configuration. The multilayer coating was deposited on face 2 of the double glazing unit. The double glazing unit thus has a light transmission of about 20%, lower than that of Example 5, but a much lower emissivity, about 18%, enabling the thermal radiation to be strongly reflected, and greatly improved energy insulation performance, the measured heat transfer coefficient U this time being equal to 1.98 W.m-2.K-1. In conclusion, the solar-protection glazing according to the invention is very advantageous for fitting into buildings, without being excluded for applications in cars and all vehicles: namely side windows, rear window and sunroof, which may also have enamelled coatings. With a fixed multilayer coating, especially with the desired TL and thermal insulation values, it is thus possible to manufacture solar-protection glazing providing' improved vision, but which can be bent/toughened/annealed, and having very good mechanical and chemical durability. Without departing from the scope of the invention, it is also possible to produce multilayer-coated curtain walling that is enamelled, rather than lacquered, this being industrially highly advantageous, enamelling taking" place during the toughening process whereas lacquering requires an additional manufacturing step. We Claim: 1. Transparent glass substrate comprising at least one glass sheet provided with a thin-film multilayer coating acting on solar radiation, having a light transmission equal to or greater than 10% and an emissivity equal to or less than 50% after a heat treatment, such as a bending or toughening treatment, characterized in that said multilayer coating comprises: - a niobium Nb functional layer with a thickness of between about 5 nm and about 35 nm; and at least one layer of another material, chosen from the group formed by Ti, Mo, B, Al or an alloy comprising at least one of these elements, which is placed relative to the glass substrate above the functional layer, said layer having a thickness of between about 1 nm and about 5 nm. 2. Transparent glass substrate according to Claim 1, comprising at least one glass sheet provided with a thin-film multilayer coating acting on solar radiation, having a light transmission equal to or greater than 20% and an emissivity equal to or less than 50% after a heat treatment, such as a bending or toughening treatment, wherein said multilayer coatingcomprises: a niobium Nb functional layer with a thickness of between about 5 nm and about 25 nm; and at least one layer of another material, chosen from the group formed by Ti, Mo, B, Al or an alloy comprising at least one of these elements, which is placed relative to the glass substrate above the functional layer, said layer having a thickness of •between about 1 nm and about 5 nm. 3. Substrate according to Claim 1 or 2, in which a layer of said material chosen from the group formed by Ti, Mo, B, Al is placed above the functional layer and in which another layer of said material is placed beneath the functional layer. 4. Substrate according to one of the preceding claims, in which the functional layer based on niobium Nb has a thickness of between 8 nm and about 20 nm. 5: Transparent substrate according to one of the preceding claims, in which the layer of material chosen from the group formed by Ti, Mo, B, Al has a thickness of between about 1 nm and about 3 nm. 6. Transparent substrate according to one of the preceding claims, in which said material is Ti. 7. Transparent substrate according to one of the preceding claims, in which the combination of the functional layer and of the layer or layers of said material is surrounded by at least one additional layer based on aluminium nitride, aluminium oxynitride, silicon nitride or silicon oxynitride, or based on a mixture of at least two of these compounds, the thickness of said additional layer or layers being adjusted in order to optimize the light transmission of the glazing". 8. Substrate according to Claim 7, in which said additional layer or layers are based on silicon nitride and are placed above arid below said combination respectively. 9. Substrate according to Claim 8, in which the layer based on silicon nitride placed above said combination is thicker than the layer placed beneath the combination by at least a factor of 1.2, especially at least a factor of 1.5 to 1.8. 10. Monolithic glazing or double glazing incorporating the substrate according to one of the preceding claims, the multilayer coating of thin layers being placed on face 2 of the monolithic glazing or of the double glazing, Or on face 3 of the double glazing, the faces of the substrate or substrates being numbered from the exterior to the interior of the building or of the passenger compartment that it equips. 11. Monolithic glazing or double glazing according to Claim 10, configured to have a light transmission TL of greater than 10%, or even greater than 20% or 30%. 12. Monolithic glazing or double glazing according to Claim 11, configured to have an emissivity of less, than 40%,. or less than 30% or even less than 20%. 13. Wall cladding panel of the curtain-walling type, incorporating at least one substrate according to one of Claims 1 to 9. 14. Side window, rear window or sunroof for an automobile or other vehicle, formed by or incorporating a substrate according to one of Claims 1 to 9. The subject of the invention is a transparent glass substrate comprising at least one glass sheet provided with a thin-film multilayer coating acting on solar radiation, having a light transmission of greater than 10% and an emissivity of less than 50% after a heat treatment, such as a bending or toughening treatment, characterized in that said multilayer coating comprises: - a niobium Nb functional layer with a thickness of between about 5 nm and about 35 nm; and - at least one layer of another material, chosen from the group formed by Ti, Mo, B, Al or an alloy comprising at least one of these elements, which is placed relative to the glass substrate above the functional layer, said layer having a thickness of between about 1 nm and about 5 nm. The invention also relates to monolithic glazing or double glazing incorporating such a substrate.

Full Text

SOLAR-PROTECTION GLAZING HAVING AN IMPROVED
LIGHT TRANSMISSION COEFFICIENT
The invention relates to glazing provided with thin-
film multilayer coatings, one of the layers of which is
a functional layer, that is to say it acts on solar
radiation. The present invention relates more
particularly to multilayer-coated glazing, especially
that intended for thermal insulation and/or solar
protection.
The term "functional" layer is understood within the
context of the present invention to mean the layer or
layers of the multilayer coating that give the latter
most of its thermal properties, as opposed to the other
layers, which are generally made of a dielectric
material and have the function of chemically or
mechanically protecting said functional layers, or else
another function, for example an optical function,
adhesion function, etc.
The solar-protection glazing according to the invention
is . more particularly suitable for fitting into
buildings: by limiting the amount of solar radiation
energy transmitted, thanks to the thin layers, such
glazing prevents the interior of rooms from being
excessively heated in the summer and thus helps to
limit the consumption of energy needed for air-
conditioning them.
The invention also relates to this type of glazing once
it has been covered with said thin layers, in order to
obtain a wall cladding panel, called more
conventionally "curtain walling", which makes it
possible, in combination with window glazing, to
provide buildings . with exterior surfaces that are
entirely glazed.
Solar-protection functional multilayer-coated glazing

is subject to a number of constraints: firstly, the
layers employed must filter out the solar radiation
sufficiently, and especially the non-visible part of
the solar, radiation lying between about 780 nm and
2500 nm, usually called solar infrared (or solar IR) .
Furthermore, this thermal performance must preserve the
optical and aesthetic appearance of the glazing: in
particular, it is desirable to be able to modulate the
level of light transmission (TL) of the substrate.
According to another important aspect, the functional
layers must be sufficiently durable and, in particular,
physically resistant, such as scratch 'resistant, and
chemically resistant - they must in particular be
moisture resistant. This is all the more important if,
in the glazing once fitted, said functional layers are
on one of the exterior faces of the glazing (as opposed
to the "interior" faces turned towards the intermediate
gas-filled, cavity of for example a double-glazing unit)
or if the glazing is single glazing, i.e. comprising
only a single glass sheet.
There is another constraint that arises during the
production of the glazing: when the latter consists at
least partly of glass substrates, these usually have to
undergo one or more heat treatments, which may be a
bending operation if it is desired to shape them (to
form a shop window), but which is often a toughening or
annea'ling operation, especially in the building sector
in which it is desired for the glazing to be more
resistant and less hazardous in the event of impacts.
The fact that the layers are deposited on the glass
before its heat treatment frequently means that they
are damaged and their properties, especially optical
properties, are substantially modified. However,
depositing the layers after the heat treatment of the
glass proves to be complex and expensive.
An example of solar-protection glazing for buildings is

given in patents EP-0 511 901 and EP-0 678 483: these
refer to functional layers for filtering out solar
radiation which are made of a nickel-chromium alloy,
optionally nitrided, made of stainless steel or of
tantalum, and which are placed between two dielectric
layers of metal oxide such as SnO2, TiO2 or Ta2O5. Such
glazing provides good solar protection, with
satisfactory mechanical and chemical durability, but it
is not truly "bendable" or "toughenable" within the
meaning • described above, since the oxide layers
surrounding the functional layer do not prevent it from
being oxidized during the bending or toughening
operation, said oxidation being accompanied by a
substantial modification in the light transmission and
in the general appearance of the glazing in its
entirety.
More recently Patent Application EP 1 218 307 has
proposed a solar-protection multilayer coating, the
functional layer of which comprises an optionally
nitrided metal chosen from Nb, Ta and Zr, the
functional layer being surmounted by protective layers
based on aluminium, nitride or oxynitride or on silicon
nitride or oxynitride. The multilayer coating according
to . th'is application gives the glazing a solar-
protection function enabling it to block out the solar
IR of the incident solar radiation. Furthermore, this
multilayer coating, proves to be resistant to the
toughening operation and mechanically and chemically
durable sufficiently to be used as face 2 of single
glazing.However, the major drawback of the multilayer
coating described in EP 1 218 307 is that the
functional layer is relatively thick, so as to obtain
the desired solar-protection effect, and consequently
has a very low TL, Of the order of 10%, or even less.
The object of the invention is thus to substantially
increase the light transmission TL of such solar-
protection glazing, without thereby such an increase

leading to an appreciable reduction in the thermal
insulation properties of the glazing, which could
result in excessive heat transfer between the interior
and the exterior of the building or of the passenger
compartment protected by said glazing.
Glazing capable of meeting such an application is known
in the field. Such glazing is coated with one or more
thin functional layers of metallic silver Ag. Such
glazing is for example described in the Patent
Application EP 718 250. It is well known that
incorporating one or more silver layers into the
glazing enables the heat transfer through the glazing
to be very greatly reduced, because of, the low
emissivity of the Ag layers, i.e. their ability to
reflect most of the thermal IR lying between 3 and
50 microns. It is then possible to obtain, using well-
known techniques and especially the addition of
dielectric interference layers of suitable index and
thickness, glazing that has a high light transmission
but the heat transfer coefficient of which nevertheless
remains very low.
The solar-protection layers based on thin silver films
thus appear to be very efficient in respect of thermal
insulation but their mechanical and chemical durability
is very limited, in particular when in contact with a
wet atmosphere, and in particular prevents them from
being used for single glazing. Furthermore, this
solution is relatively expensive to implement in the
case of double glazing.
The invention therefore consists in the development of
novel thin-film multilayer coatings that act on solar
radiation, with a view to manufacturing improved solar-
protection glazing. The intended improvement is in
particular the establishment of a better compromise
between durability, thermal properties, optical
properties and solar-protection function, in particular

light transmission, and capability of withstanding heat
treatment without being damaged when the substrate
bearing the multilayer coating is of the glass type.
'More precisely, the object of the present invention is
therefore to provide glazing coated with thin layers
that give it good solar-protection properties and a
light transmission equal to or greater than 10% or even
20%, but however still having an acceptable heat
transfer coefficient, thanks in particular to a
sufficiently low emissivity coefficient α, as defined
according to the European standard prEN 410, said
multilayer-doated glazing also being able to undergo a
heat treatment as explained above.
According to the- invention, such single or multiple
glazing has been able to be obtained that has in
particular:
a light transmission equal to or greater than
10% or greater than 20%, or even 30% or 40%;
- an emissivity equal to or less than 50%,
preferably,less than 40% or less than 30% or even 20%;
resistance to heat treatment such as a bending
or toughening operation, especially with the above
properties being maintained, and chemical resistance,
as described above; and
good chemical and mechanical durability.
The subject of the invention thus firstly consists of a
transparent glass substrate comprising at least one
glass sheet provided with a thin-film multilayer
eoating acting on solar radiation, having a light
transmission equal to or greater than 10% or even
greater than 20% and an emissivity equal to or less
than 50%, or less than 40%, or even less than 30% or
20% after a heat treatment, such as a bending or
toughening treatment, said multilayer coating
comprising:
a functional layer based on niobium Nb with a

thickness of between about 5 nm and about 35 nm; and
at least one layer of another material, chosen
from the group formed by Ti, Mo, B, Al or an alloy
comprising at least one of these elements, which is
placed relative to the glass substrate above the
functional . layer, said layer having a thickness of
between about 1 nm and about 5 nm.
According to a possible embodiment, the
transparent glass substrate comprises . at least one
glass sheet provided with a thin-film multilayer
coating acting on solar radiation, having a light
transmission equal to or greater than 20% and an
emissivity equal to or less than 50%. after a heat
treatment, such as a bending or toughening treatment,
said multilayer coating comprising:
a functional layer based on niobium Nb with a
thickness of between about 5 nm and about 25 nm; and
at least one layer of another material, chosen
from the group formed by Ti, Mo, B, Al or an alloy
comprising at least one of these elements, which is
placed relative to the glass substrate above the
functional layer, said layer having a thickness of
between about 1 nm and about 5 nm.
Preferably, a layer of said material chosen from the
group formed by Ti, Mo, B, Al is placed above the
functional layer and another layer of said material is
placed beneath the functional layer.
Typically, the functional layer based on niobium Nb has
a thickness of between 8 nm and about 20 nm, for
example of between 8 nm and 15 nm.
Typically, the layer of material chosen from the group
formed by Ti, Mo, B, Al has a thickness of between
about 1 nm and about 3 nm.
Preferably; said material is Ti.

According to the invention, the combination of the
functional layer and of the layer or layers of said
material is surrounded by at least one additional layer
based on aluminium nitride, aluminium oxynitride,
silicon nitride or silicon oxynitride, or based on a
mixture of at least two of these compounds, the
thickness of said additional layer- or layers being
adju'sted in order to optimize the light transmission of
the glazing.
For example, said additional layer or layers are based
on silicon nitride, and are placed above and below said
combination respectively.
According to one possible embodiment, the layer based
on silicon nitride placed above said combination is
thicker than the layer placed beneath the combination
by at least a factor of 1.2, especially at least a
factor of 1.5 to 1.8.
The invention also relates to monolithic glazing or
double glazing incorporating the substrate as described
above, the multilayer coating of thin layers being
placed on face 2 of the monolithic glazing or of the
double glazing, or on face 3 of the double glazing, the
faces of the substrate or substrates being numbered
from the exterior to the interior of the building or of
the passenger compartment that it equips.
According to one embodiment, the monolithic glazing or
double glazing is configured to have a light
transmission TL of , greater than 10%, 20% or, even 30%,
or even greater than 40%. The monolithic glazing or
double glazing may also be configured to have an
emissivity of less than 40%, or less than 30% or even
less than 20%.
Finally, the present invention relates to a wall
cladding panel of the curtain-walling type,

incorporating at least one substrate as described above
or to a side window, rear window or sunroof for an
automobile, or another vehicle, formed by or
incorporating said substrate.
According to the invention, the functional layers of
the invention make it possible for the substrate to
have a relatively high light transmission, while still
maintaining an appreciable solar-protection effect,
despite the relatively small thickness of the
functional layer: the measurements made show in fact a
good compromise between the level of light transmission
TL and the heat transfer coefficient U of the
multilayer-coated substrate, as measured by its
emissivity a. In the present description, the
emissivity is a normal emissivity as de'fined according
to the standard prEN 410.
The use of a very thin layer of a metal of the group
Ti, Mo, B, Al, in particular Ti, makes it possible
according to the invention to guarantee the
toughenability of the multilayer coating without an
accompanying degradation in the functional properties
thereof. In particular, the change in optical
properties, especially the light transmission, caused
by a toughening heat treatment, is low. Likewise, the
emissivity of the functional layer remains low thanks
to the addition of this additional thin metal layer.
According to one possible embodiment of the invention,
the thin layer of metal of the group Ti, Mo, B, Al is
deposited at least on top of the Nb functional layer.
Preferably, said layer is deposited on top of and
beneath the Nb layer.
In the present description, the terms "on top of" and
"beneath" refer to the respective position of said
layers relative to the glass substrate supporting the
multilayer coating comprising said layers.

According to one embodiment of the invention, it is
preferable to deposit also an overlayer based on
silicon or aluminium nitride (Si3N4 and A1N) or based on
silicon or aluminium oxynitride (SiON and A1N0 in
short, without judging the respective quantities of Si,
O and N) . The thickness of such layers is adjusted so
as to obtain an antireflection effect enabling the
light transmission of the multilayer-coated glazing to
be optimized. Such layers may also play, to a lesser
extent, a role of protecting the functional layers of
the invention. Without departing from the scope of the
invention, it is also possible according to the
invention to dope these layers with elements such as
Zr, B, etc., so as to modify the colour of the glazing
in transmission and/or in reflection, in accordance
with the well-known techniques in the field.
Preferably, the multilayer coating according to . the
invention comprises, between the substrate and the
functional layer, at least one underlayer made of a
transparent dielectric, especially chosen, as in the
case of. the overlayer, to be silicon nitride or
oxynitride and/or aluminium nitride or oxynitride, or
else; silicon oxide SiO2. In particular, its presence
may make it possible for the optical appearance
conferred on the carrier substrate by its multilayer
coating to be varied more flexibly. Furthermore, in the
case of heat treatment, said underlayer may constitute
an additional barrier, in particular to oxygen and to
alkali metals from the glass substrate, which species
are liable to migrate due to the heat and degrade , the
multilayer coating.
A very preferred variant of the invention may for
example consist in using both an overlayer and an
underlayer based on silicon nitride.
The thickness of the overlayer is preferably between 5

and 70 nm, especially between 40 and 60 nm. The
thickness of the optional underlayer is preferably
between 5 and 120 nm.
When there is a single underlayer of the Si3N4 type, its
thickness is for example between 30 and 50 nm.
the underlayer and/or the overlayer may in fact form
part of a superposition of dielectric layers. One or
other layer may thus be combined with other layers of
different refractive indices. Thus, the multilayer
coating may comprise, between the substrate and the
functional layer (or on top of the functional layer) an
alternation of three, high index/low index/high index,
layers, the "high index" layer (having an index of at
least 1.8 to 2) or one of said layers possibly being
the sublayer of the invention of the Si3N4 or A1N type
and the "low index" layer (for example of index less
than 1.7.) possibly being made of silicon oxide SiO2.
More particularly, a very preferred embodiment of the
invention consists of single or multiple glazing
comprising a substrate on which is deposited a
multilayer coating comprising a functional layer based
on niobium with a Ti layer on either side thereof, the
combination of the Ti/Nb/Ti layers itself being
surmounted by an overlayer based on silicon nitride and
by an underlayer also based on silicon nitride.
The subject of the invention applies both to single or
"monolithic" glazing, i.e.. consisting of a single
substrate, and insulating multiple glazing of the
double-glazing type. Preferably, whether in monolithic
glazing or double glazing, the multilayer coatings are
placed on face' 2 (conventionally, the faces of the
panes/substrates of glazing are numbered from the
outside to the inside of the passenger compartment/room
equipped therewith) and protect against solar
radiation. Without departing from the scope of the

invention, the multilayer coatings may also be
deposited on face 3 of double glazing.
Another subject of the invention is a multilayer-coated
substrate at least partially opacified by covering of
the lacquer or enamel type, with the purpose of
producing curtail walling, where the opacifying
covering is in direct contact with the multilayer
coating. The multilayer coating may therefore be
exactly the same both for window glazing and for
curtain walling.
Although the application more particularly intended by
the invention is architectural glazing, it is clear
that other applications can be envisaged, especially
automotive glazing (apart from windscreens, which
require a very high light transmission) , such as the
side windows, sunroof and rear window.
The invention and its advantages will be described in
greater detail below by means of. the following non-
limiting examples according to the invention and
comparative examples. In all the examples and the
description, the thicknesses are geometric thicknesses.
All the substrates are made of clear glass 6 mm in
thickness of the Planilux type sold by Saint-Gobain
Vitrage.
All the layers were deposited in a known manner by
magnetron sputtering. The metal (Nb, Ti) layers were
deposited from metal targets in an inert atmosphere
(100%- Ar) , the silicon nitride Si3N4 layers were
deposited from a suitable silicon target (the silicon
being doped with 8% aluminium by weight) in a reactive
atmosphere containing nitrogen (40% Ar/60% N2) . The
Si3N4 layers therefore contain a little aluminium.

EXAMPLE 1 (according to EP 1 218 307)
This example has an Nb functional layer, an Si3N4
underlayer and an Si3N4 overlayer according to the
following sequence:
glass/Si3N4 (10 nm)/Nb' (35 nm)/Si3N4 (30 nm) .
After the layers had been deposited, the substrate
underwent the following heat treatment:
heating at 620°C for 10 minutes followed by
quenching. .
EXAMPLE 2 (comparative example)
In this example, the same functional layer and the
other layers as in Example 1 were used, these being
deposited on the same substrate but with modifications
in the thicknesses of the Si3N4 underlayer and
overlayer:
glass/Si3N4 (40 nm)/Nb (10 nm)/Si3N4 (60 nm) .
The substrate coated with the multilayer coating then
underwent the same heat treatment as described in
Example 1.
EXAMPLE 3 (according to the invention)
This example uses the same sequence of layers as in
Example- 2, deposited on the same substrate, but with a
very thin metallic titanium layer deposited on top of
the functional layer. The multilayer coating thus
comprises the following succession of layers:
glass/Si3N4 (40 nm)/Nb (10 nm)/Ti (about 1 nm)/Si3N4 (60 nm) .
The substrate coated with the multilayer coating then
underwent the same heat treatment as described in
Example 1 or Example 2.

EXAMPLE 4 (comparative example)
This example uses the same sequence of layers as in
Example 2, deposited on the same substrate, but a very
thin metallic titanium layer is deposited beneath the
functional layer. The multilayer coating thus comprises
the following succession of layers:
glass/Si3N4 (40 nm) /Ti (about 1 nm)/Nb (-10 run) /Si3N4 (60 nm) .
The -substrate coated with the multilayer coating then
undergoes the same heat treatment as described in
Example 1 or 2.
EXAMPLE 5 (according to the invention)
This example uses the same sequence of layers as in
Example 2, deposited oh the same substrate, but a very
thin titanium metal, layer is deposited on top of and
beneath the functional layer. The multilayer coating
thus comprises the following succession of layers:
glass/Si3N4 (40 nm)/Ti (≈ 1 nm) /Nb (10 nm)/Ti (≈ 1 nm)
/Si3N4 (60 nm) .
The substrate coated with the multilayer coating then
underwent . the same heat treatment as described in
'Example 1 or 2.
EXAMPLE 5b (according to the invention)
This example uses the, same sequence of layers as in
Example 2, deposited on the same substrate. The
multilayer coating thus comprises the following
succession of layers.:
glass/Si3N4 (40 nm)/Ti (≈ 1 nm)/Nb (19 nm)/Ti (≈ 1 nm)
/Si3N4 (50 nm).
The substrate coated with the multilayer coating then
underwent the same heat treatment as described in
Example 1 or 2.

EXAMPLE 6 (comparative example)
This example used the same sequence of layers as in
Example 2, deposited on the same substrate, but a very
thin NiCr layer is deposited on top of and beneath the
functional layer. The multilayer coating thus comprises
the following succession of layers:
glass/Si3N4 (40 nm) /NiCr (≈1 nm) /Nb (10 ran) /NiCr (≈1 nm)
/ Si3N4 (60 nm).
The substrate coated with the multilayer coating then
underwent the same heat treatment as described in
Example 1 or 2.
Table 1 below gives the measured optical transmission
TL values (the light transmission being in % under
illuminant D65) and the emissivity a values, which are
calculated according to the prEN 410 and NFEN 673
standards, for Examples 1 to 6 above.
The values are given twice, once before heat treatment
and once after heat treatment. In the table 1, the
relative rise Aa of the emissivity a value, after the
quenching; is reported in percentage.

The values given in Table 1 show that Examples 3, 5. and
5b according to the invention provide a much higher
light transmission than the solar-protection glazing of
the prior art, while still maintaining acceptable
energy performance, after the heat treatment and
toughening operation. The comparison of the emissivity
values obtained after toughening for Example 4 with the
values obtained for Examples 3, 5 and 5b show that the
best compromises are obtained when a Ti metal layer is
deposited at least on top of the Nb functional layer.
The results obtained for Example 2, which is not
according to the present invention (since the
multilayer coating is not provided with one or more Ti

metal layers), are much inferior after the toughening
operation. These multilayer coatings are clearly not
bend-able/ toughenable within the meaning of the
invention. The heat treatment significantly degrades
the thermal insulation properties: the emissivity
values of such glazing thus appear to be much too high.
The results obtained according to Example 6, in which
the metal layer deposited on the functional layer is
this time made of NiCr, are similar to those obtained
for Example .2, i.e. in the absence of a layer.
EXAMPLE 7 (according to the invention)
For this example, a multiple glazing unit was
constructed from the substrate of Example 5 (after the
toughening operation). The multiple glazing unit was
assembled according to the conventional techniques in a
6/12/6clear (100% air) configuration, i.e. in such a way
that it is made up of two clear glass sheets 6 mm in
thickness separated by a 12 mm thick air space. The
multilayer coating was deposited on face 2 of the
double glazing unit.
The double glazing unit has a light transmission of 36%
but a relatively low emissivity, about 37%, enabling
most of the thermal IR radiation to be reflected. The
energy insulation performance is thus very
satisfactory, the heat transfer coefficient U having
been measured to be 2.30 W.m-2.K-1. For comparison, the
coefficient U is equal to 2.90 W.m-2.K-1 for a simple,
i.e. not multilayer-coated, double glazing unit. Again
for comparison, the low-E transparent glazing of the
prior art, incorporating as functional layer a not
easily toughenable silver layer, has a coefficient of
around 1.8 W.m-2.K-1, but are very much less, durable,
both in terms of chemical resistance and mechanical
resistance.

EXAMPLE 8 (according to the invention)
In this example, the aim was to obtain a multiple
glazing unit based on a substrate in which the layers
of the multilayer coating have thicknesses suitable
this time for maximizing the energy performance of the
glazing.
The . multilayer coating thus comprises the following
succession of layers:
glass/Si3N4 (40 nm) /Ti (≈ 1 nm)/Nb (20 nm) /Ti .(≈ 1 nm)
/Si3N4 (54 nm) .
The substrate coated with the multilayer coating then
underwent the same heat treatment as described above.
A multiple glazing unit was then manufactured from this
substrate. In a manner similar to Example 7, the
multiple glazing unit was assembled in a 6/12/6clear
(100% air) configuration. The multilayer coating was
deposited on face 2 of the double glazing unit.
The double glazing unit thus has a light transmission
of about 20%, lower than that of Example 5, but a much
lower emissivity, about 18%, enabling the thermal
radiation to be strongly reflected, and greatly
improved energy insulation performance, the measured
heat transfer coefficient U this time being equal to
1.98 W.m-2.K-1.
In conclusion, the solar-protection glazing according
to the invention is very advantageous for fitting into
buildings, without being excluded for applications in
cars and all vehicles: namely side windows, rear window
and sunroof, which may also have enamelled coatings.
With a fixed multilayer coating, especially with the
desired TL and thermal insulation values, it is thus

possible to manufacture solar-protection glazing
providing' improved vision, but which can be
bent/toughened/annealed, and having very good
mechanical and chemical durability.
Without departing from the scope of the invention, it
is also possible to produce multilayer-coated curtain
walling that is enamelled, rather than lacquered, this
being industrially highly advantageous, enamelling
taking" place during the toughening process whereas
lacquering requires an additional manufacturing step.

We Claim:
1. Transparent glass substrate comprising at least
one glass sheet provided with a thin-film multilayer
coating acting on solar radiation, having a light
transmission equal to or greater than 10% and an
emissivity equal to or less than 50% after a heat
treatment, such as a bending or toughening treatment,
characterized in that said multilayer coating
comprises:
- a niobium Nb functional layer with a thickness
of between about 5 nm and about 35 nm; and
at least one layer of another material, chosen
from the group formed by Ti, Mo, B, Al or an alloy
comprising at least one of these elements, which is
placed relative to the glass substrate above the
functional layer, said layer having a thickness of
between about 1 nm and about 5 nm.
2. Transparent glass substrate according to Claim 1,
comprising at least one glass sheet provided with a
thin-film multilayer coating acting on solar radiation,
having a light transmission equal to or greater than
20% and an emissivity equal to or less than 50% after a
heat treatment, such as a bending or toughening
treatment, wherein said multilayer coatingcomprises:
a niobium Nb functional layer with a thickness
of between about 5 nm and about 25 nm; and
at least one layer of another material, chosen
from the group formed by Ti, Mo, B, Al or an alloy
comprising at least one of these elements, which is
placed relative to the glass substrate above the
functional layer, said layer having a thickness of
•between about 1 nm and about 5 nm.
3. Substrate according to Claim 1 or 2, in which a
layer of said material chosen from the group formed by
Ti, Mo, B, Al is placed above the functional layer and
in which another layer of said material is placed

beneath the functional layer.
4. Substrate according to one of the preceding
claims, in which the functional layer based on niobium
Nb has a thickness of between 8 nm and about 20 nm.
5: Transparent substrate according to one of the
preceding claims, in which the layer of material chosen
from the group formed by Ti, Mo, B, Al has a thickness
of between about 1 nm and about 3 nm.
6. Transparent substrate according to one of the
preceding claims, in which said material is Ti.
7. Transparent substrate according to one of the
preceding claims, in which the combination of the
functional layer and of the layer or layers of said
material is surrounded by at least one additional layer
based on aluminium nitride, aluminium oxynitride,
silicon nitride or silicon oxynitride, or based on a
mixture of at least two of these compounds, the
thickness of said additional layer or layers being
adjusted in order to optimize the light transmission of
the glazing".
8. Substrate according to Claim 7, in which said
additional layer or layers are based on silicon nitride
and are placed above arid below said combination
respectively.
9. Substrate according to Claim 8, in which the layer
based on silicon nitride placed above said combination
is thicker than the layer placed beneath the
combination by at least a factor of 1.2, especially at
least a factor of 1.5 to 1.8.
10. Monolithic glazing or double glazing incorporating
the substrate according to one of the preceding claims,
the multilayer coating of thin layers being placed on

face 2 of the monolithic glazing or of the double
glazing, Or on face 3 of the double glazing, the faces
of the substrate or substrates being numbered from the
exterior to the interior of the building or of the
passenger compartment that it equips.
11. Monolithic glazing or double glazing according to
Claim 10, configured to have a light transmission TL of
greater than 10%, or even greater than 20% or 30%.
12. Monolithic glazing or double glazing according to
Claim 11, configured to have an emissivity of less, than
40%,. or less than 30% or even less than 20%.
13. Wall cladding panel of the curtain-walling type,
incorporating at least one substrate according to one
of Claims 1 to 9.
14. Side window, rear window or sunroof for an
automobile or other vehicle, formed by or incorporating
a substrate according to one of Claims 1 to 9.

The subject of the invention is a transparent glass
substrate comprising at least one glass sheet provided
with a thin-film multilayer coating acting on solar
radiation, having a light transmission of greater than
10% and an emissivity of less than 50% after a heat
treatment, such as a bending or toughening treatment,
characterized in that said multilayer coating
comprises:
- a niobium Nb functional layer with a thickness
of between about 5 nm and about 35 nm; and
- at least one layer of another material, chosen
from the group formed by Ti, Mo, B, Al or an alloy
comprising at least one of these elements, which is
placed relative to the glass substrate above the
functional layer, said layer having a thickness of
between about 1 nm and about 5 nm.
The invention also relates to monolithic glazing or
double glazing incorporating such a substrate.

Documents:

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Patent Number

279771

Indian Patent Application Number

2599/KOLNP/2010

PG Journal Number

05/2017

Publication Date

03-Feb-2017

Grant Date

30-Jan-2017

Date of Filing

16-Jul-2010

Name of Patentee

SAINT-GOBAIN GLASS FRANCE

Applicant Address

18 AVENUE D' ALSACE F-92400 COURBEVOIE FRANCE

Inventors:

#	Inventor's Name	Inventor's Address
1	GOUARDES, ERIC	15 RUE IDRAC, 31000 TOULOUSE, FRANCE
2	HENRY, SÉBASTIEN	11 RUE MODIGLIANI, F-91440 BURES FRANCE
3	BELLIOT, SYLVAIN	28 RUE DU COLONEL ROZANOFF, F-75012 PARIS FRANCE

PCT International Classification Number

C03C 17/36

PCT International Application Number

PCT/FR2009/050299

PCT International Filing date

2009-02-25

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	0851263	2008-02-27	France