Low emissivity and solar protection glazing

Abstract

The invention relates to a glazing unit comprising a transparent substrate (1) provided with a stack of thin layers comprising an alternating arrangement of three IR-reflecting Ag-containing functional layers Ag1 (4), Ag2 (9), Ag3 (14) and four dielectric coatings D1, D2, D3 and D4, such that each functional layer is surrounded by a dielectric coating, whereby D1 does not comprise silicon nitride and the stack of thin layers comprises, in order starting from the substrate, a lower layer (2) comprising a metal oxide in direct contact with the substrate (1), a contact layer (3) comprising ZnO in contact with Ag1 (4), a contact layer (5) comprising ZnO in contact with Ag1 (4), a first layer (6) comprising a mixed oxide of zinc and tin ZSO1 in contact with C2 (5), the first layer comprising silicon nitride SiN1 (7) inserted in ZSO1, and a second layer (8) comprising a ZnO-containing functional layer (9) in contact with C2 (6). A contact layer C3 (8) comprising ZnO above SO1 (6) and in contact with Ag2 (9), a contact layer C4 (10) comprising ZnO in contact with Ag2 (9), a second layer (11) comprising a mixed oxide of zinc and tin ZSO2 in contact with C4 (9), the second layer (11) comprising silicon nitride SiN2 (12) inserted in ZSO2, a contact layer C5 (12) comprising ZnO in contact with Ag3, a contact layer C6 comprising ZnO in contact with Ag3, a third layer comprising a mixed oxide of zinc and tin ZSO3 in contact with C6, the third layer comprising silicon nitride in contact with ZSO3, and an upper layer comprising a metal oxide or metal nitride, the ratio of the sum of the thicknesses of the layers comprising a mixed oxide of zinc and tin to the thickness of the layer of silicon nitride decreasing from D2 to D3 to D4.

Description

[Technical field]

[0001] The present invention relates to glazing systems that simultaneously have low emissivity and solar protection properties and low visible reflectance (especially low solar heat gain coefficient). These glazings can be integrated into windows in buildings or can be used in the field of automotive glazing. [Background technology]

[0002] Such glazing systems are generally formed from a transparent substrate, such as a glass sheet, covered by a system of thin layers including at least two functional layers based on an infrared radiation reflecting material and at least three dielectric coatings, each functional layer being surrounded by a dielectric coating. The functional layers are generally layers of silver having a thickness of a few nanometers. In relation to the dielectric layers, they are transparent and are conventionally made of metals or silicon oxides and / or silicon nitrides. These different layers are deposited using vacuum deposition techniques, such as magnetic field assisted cathode sputtering, more generally called "magnetron sputtering".

[0003] These glazing systems have solar protection properties that can, for example, reduce the risk of excessive overheating in enclosed spaces with large glazing surfaces, thus reducing the power load considered for air conditioning in summer. In this case, the glazing must allow the passage of the minimum possible amount of total solar energy radiation; that is, it must have the minimum possible solar heat gain coefficient (SF or g). However, it is highly desirable to guarantee a certain level of light transmittance (LT) in order to provide a sufficient level of illumination inside the building. These somewhat conflicting requirements represent the desire to obtain glazing units with a high selectivity (S), defined by the ratio of light transmittance to solar heat gain coefficient. These glazing systems also have a low emissivity, which allows a reduction of heat loss through high-wave infrared radiation. They therefore improve the insulation of large glazing surfaces and reduce energy losses and heating costs in cold seasons.

[0004] These glazing systems are typically assembled as multiple glazing units, such as double or triple glazing units or sometimes laminated glazing units, in which a glass sheet supporting the laminated unit is combined with one or more other glass sheets, with or without a coating, and the low-emissivity multi-layer stack is in contact with the interior space between the glass sheets in the case of a multiple glazing unit, or with the interlayer adhesive of the laminated unit in the case of a laminated glazing unit.

[0005] In some cases, operations are required to mechanically reinforce the glazing, such as thermal strengthening of one or more glass sheets, to improve their resistance to mechanical stresses. Also, for certain applications, it may be necessary to impart a relatively large or relatively small number of complex bends to the glass sheets using folding operations at high temperatures. In the process of manufacturing and forming glazing systems, there are certain advantages to carrying out these heat treatment operations on already coated substrates, instead of coating the already treated substrates. These operations are carried out at relatively high temperatures, at which functional layers based on infrared reflective materials, such as those based on silver, tend to deteriorate or lose their optical properties and properties related to infrared radiation. These heat treatments in particular comprise a step of heating the glass sheets in air to temperatures above 560°C, such as 560°C to 700°C, in particular 640°C to 670°C, for a period of about 3, 4, 6, 8, 10, 12 or even 15 minutes, depending on the type of treatment and the thickness of the sheets. In the case of a folding process, the glass sheet can then be folded into the desired shape. The tempering process then comprises the step of rapidly cooling the surfaces of the flat or folded glass sheet by air jets or cooling fluids in order to obtain mechanical reinforcement of the sheet.

[0006] Therefore, in the case where the coated glass sheet has to undergo a heat treatment, very specific precautions must be taken to form a coating structure that can withstand the heat strengthening and / or folding treatment, often referred to below by the term "temperable", without losing the light and / or energy properties generated. In particular, the dielectric materials used to form the dielectric coating must withstand the high temperatures of the heat treatment without exhibiting adverse structural changes. Examples of materials that are particularly suitable for these uses are mixed oxides of zinc-tin, silicon nitride and aluminium nitride. It is also necessary to ensure that functional layers, such as layers based on silver, are not oxidized during the treatment, for example by ensuring that at the moment of the treatment there is a barrier layer capable of oxidation instead of silver by capturing free oxygen or by preventing free oxygen migrating towards the silver during the heat treatment.

[0007] In addition to this, the formation of these layer assemblies must result in a satisfactory color in both reflection and transmission, with the demand tending towards the most perfect neutrality possible. The problem is to combine the colorimetric requirements simultaneously with all of the relevant "basic" conditions: high light transmission, very low emissivity, ability to withstand heat treatment.

[0008] Another requirement that increasingly needs to be taken into account results from the fact that non-heat-treated products and other heat-treated products often have to be combined with each other for the same application, for example in the same building facade.

[0009] Moreover, while the properties governing the optical properties of the materials forming the layers are well known, further difficulties exist in the manufacturing methods of these glazing units: the deposition conditions, and in particular the deposition rate, depend on the properties of the materials considered. The deposition rate must be sufficient for an economically acceptable industrial production. It depends on several factors that guarantee the stability of the functions over time over the entire surface of the sheet and the absence of defects in the layer.

[0010] Several solutions have been proposed to meet these diverse requirements. In particular, coating stacks of three silver-based functional layers have been shown to achieve very good solar protection properties. However, no solution has been found that provides really satisfactory glazing units that allow us to comply with the requirements of these new demands.

[0011] WO2011020974 describes a coating stack of three silver-based functional layers of the type Glass / Dielectric / Ag / Dielectric / Ag / Dielectric / Ag / Dielectric III, where each dielectric contains a silicon nitride layer, which allows us to understand that the coating stacks it describes can be heat treated and that they show only minor variations in their optical properties after heat treatment. While the silicon nitride layer is beneficial, skipping the first nitride layer is an opportunity to reduce the number of coating areas, since the nitride must be deposited separately from the oxide without compromising the durability of the coating. Summary of the Invention [Problem to be solved by the invention]

[0012] The object of the present invention is to develop a new type of laminate of thin low emissivity and solar protection layers that is effective in terms of optical and energy properties, in particular has a low level of reflectance, and retains these performance levels regardless of whether it is subsequently subjected to a heat treatment of the tempering or folding type. [Means for solving the problem]

[0013] In the present invention, the following information is used: a. Luminous transmission (LT) is the percentage of incident luminous flux transmitted by the glazing at illuminant D65 / 2°. b. Light reflectance (LR) is the percentage of the incident luminous flux reflected by the glazing at illuminant D65 / 2°. It can be measured on a single glazing from the layer side (LRc) or the substrate side (LRg). It can be measured on the exterior side (LRext) of a building or vehicle or on the interior side (LRint) of a building or vehicle, especially on multiple glazing units or one laminate glazing. c. Energy transmittance (ET) is the percentage of incident energy radiation transmitted by the glazing calculated according to the EN410 standard. d. Energy reflectance (ER) is the percentage of incident energy radiation reflected by the glazing calculated according to standard EN 410. It can be measured on the outside of a building or vehicle (ERext) or on the inside of a building or vehicle (ERint). e. The solar heat gain coefficient (SF or g) is the percentage of incident energy radiation that is directly transmitted by and absorbed by the glazing on the one hand and then radiated in the opposite direction towards the energy source in relation to the glazing. It is calculated here according to standard EN 410. The fU values ​​(coefficient k) and emissivity (ε) are calculated according to standards EN673 and ISO10292. g.CIELAB1976 value (L * a * b * ) are used to define color hues. They are measured with illuminant D65 / 10°. h.ΔE * =[(L * ) 2 +(a * ) 2 +(b*2 )] 1 / 2 represents the variation in shade upon heat treatment, i.e. the difference in color between before and after heat treatment. i. Resistance / square (R2) ("sheet resistance"), expressed in Ω / square (Ω / □), measures the electrical resistance of a thin film.

[0014] When values ​​are referred to as "in the range of a to b," they may be equal to a or b.

[0015] The positioning of the stack of layers within a multiple glazing structure is given according to the conventional sequential numbering of the faces of the glazing unit, with face 1 being on the exterior of the building or vehicle and face 4 (in the case of a double glazing unit) or face 6 (in the case of a triple glazing unit) being on the interior.

[0016] When silicon nitride or silicon oxide layers are referred to herein, it is understood that the layers may also contain small amounts of aluminum, as is well known in the art of magnetron sputtering coating, such aluminum being present as a doping agent, typically in amounts up to 10% by weight.

[0017] For purposes of clarity, when terms such as "lower", "upper", "bottom", "top", "first" or "last" are used herein, this is always in the context of a layer sequence starting with the bottom glass and progressing upward, away from this glass. Such a sequence may include further intermediate layers between the layers being defined, except when direct contact is defined.

[0018] The invention relates to a glazing according to claim 1, the dependent claims representing preferred embodiments.

[0019] The present invention relates to a glazing unit comprising a transparent substrate provided with a stack of thin layers comprising an alternating arrangement of three infrared radiation reflecting functional layers and four dielectric coatings, such that each functional layer is surrounded by a dielectric coating. In fact, the present invention only relates to a coating stack comprising, starting from the substrate surface, three functional silver-based metal layers, designated first functional layer Ag1, second functional layer Ag2 and third functional layer Ag3, and four dielectric coatings, designated D1, D2, D3 and D4, starting from the substrate surface, which a.D1 does not have a layer containing silicon nitride and includes a lower layer containing a metal oxide in direct contact with the substrate, and a contact layer C1(3) containing zinc oxide located directly below the upper first functional layer Ag1 and in contact with the first functional layer Ag1; b.D2 is 1. a contact layer C2 containing zinc oxide located directly above and in contact with the lower first functional layer Ag1; 2. A first layer comprising a mixed oxide of zinc and tin in contact with C2, 3. A first layer comprising silicon nitride intercalated within a first layer comprising a mixed oxide of zinc and tin; 4. a contact layer C3 comprising zinc oxide above the first layer comprising a mixed oxide of zinc and tin and below the second functional layer Ag2 and in contact with said second functional layer Ag2; Including, c.D3 is 1. a contact layer C4 containing zinc oxide located directly above and in contact with the second functional layer Ag2 located below; 2. A second layer comprising a mixed oxide of zinc and tin in contact with C4, 3. A second layer comprising silicon nitride intercalated within a second layer comprising a mixed oxide of zinc and tin; 4. A contact layer C5 containing zinc oxide located directly below and in contact with the upper third functional layer Ag3; Including, d.D4 is, 1. a contact layer C6 containing zinc oxide located directly above and in contact with the lower third functional layer Ag3; 2. A third layer comprising a mixed oxide of zinc and tin in contact with C6, 3. a third layer comprising silicon nitride in contact with said third layer comprising a mixed oxide of zinc and tin; 4. An upper layer comprising a metal oxide or a metal nitride; The present invention is characterized in that it comprises It is further characterized in that the ratio of the sum of the thicknesses of the layers containing the mixed oxide of zinc and tin to the thickness of the layer of silicon nitride decreases from D2 to D3 to D4, and the sum of the thicknesses of D1, D2, D3, and D4 is less than 225 nm.

[0020] The first layer SiN1 comprising silicon nitride is inserted into the first layer ZSO1 comprising a mixed oxide of zinc and tin, which means that ZSO1 is separated in two parts: one part ZSO1 is below and in contact with SiN1, and another part ZSO1 is above and in contact with SiN1. In other words, the first layer comprising silicon nitride is located between two sublayers of the first layer comprising a mixed oxide of zinc and tin, namely the lower sublayer ZSO1a and the upper sublayer ZSO1b.

[0021] The second layer SiN2 containing silicon nitride is inserted into the second layer ZSO2 containing a mixed oxide of zinc and tin, which means that ZSO2 is separated in two parts: one part ZSO2 is below and in contact with SiN2, and another part ZSO2 is above and in contact with SiN2. In other words, the second layer containing silicon nitride is located between two sublayers of the second layer containing a mixed oxide of zinc and tin, namely the lower sublayer ZSO2a and the upper sublayer ZSO2b. [Brief description of the drawings]

[0022] [Figure 1]FIG. 1 shows a schematic diagram of a transparent substrate provided with a stack of thin layers according to one embodiment of the present invention.

[0023] [Diagram 2] FIG. 2 shows another schematic diagram of a transparent substrate provided with a stack of thin layers according to an embodiment of the present invention.

[0024] [Diagram 3] FIG. 1 shows a schematic diagram of a transparent substrate provided with a stack of thin layers according to one embodiment of the present invention.

[0025] [Figure 4] The refractive indices of selected thin film materials are shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Due to the particular selection of the layers of the coating stack, in particular the ratio of the sum of the thicknesses of the layers containing the mixed oxide of zinc and tin to the thickness of the layers of silicon nitride, which decreases from D2 → D3 → D4, layer stacks are obtained which, on a substrate of 6 mm normal soda-lime glass, show either: a. low visible light reflectance in both LRc and LRg with LRc and LRg independently of 5% to 15%, preferably 7% to 10%, measured on a single pane of glass; b. High selectivity (the ratio of visible light transmittance LT to solar heat gain coefficient SF) of LT / SF≧1.99 before tempering or LT / SF≧1.92 after tempering; c. A visible light transmittance measured on a single pane of glass that is 62%≧LT≧70%, preferably 65%≧LT≧68%. In an alternative embodiment, a visible light transmittance measured on a single pane of glass that is 52%≧LT≧60%, preferably 55%≧LT≧58%. d.80≦L * ≦90, -12≦a * ≦-2, -2≦b * ≦8, preferably 84≦L * ≦86, -8≦a * ≦-6, 2≦b * Color value L in transmission is ≦4* , a * , b * , e.30≦L * ≦42, -7≦a * ≦3, -18≦b * ≦-8, preferably 36≦L * ≦38, -3≦a * ≦-1, -14≦b * Color value L in reflection on the glass side (opposite the coated side) ≦-12 * , a * , b * , f. low emissivity (ε≦0.038, preferably ε≦0.025) to limit heat loss; g. A low solar heat gain coefficient SF having SF<35%, preferably SF≦33%, to allow for a reduction in the risk of excessive overheating as a result of insolation; h. The ability of the coating to be heat treated to resist high temperatures or to be used without heat treatment; i. A defect-free aesthetic appearance, where haze is very limited or even absent without or after heat treatment, and there are no unacceptable spots after heat treatment; j. Retention of optical and energy properties in a substantially unchanged state, permitting the use of the product in a heat-treated or non-lined condition ("self-matchability"); little or no change in color in transmission and reflection measured in a single glazing configuration (ΔE * ≦8, preferably ≦5, more preferably ≦2) and / or there is no or little change in the light transmission and reflection and energy values ​​(Δ=|(value before heat treatment)-(value after heat treatment)|≦7, preferably ≦6), k. Sufficient chemical stability for use without heat treatment or for the time interval before heat treatment, and in particular the results of a climate chamber test and a salt spray test according to standard EN1036-2012 not imparting any defects visible to the naked eye or any discoloration after 1 day, preferably after 3 days.

[0027] Thus, the glazing unit can provide any of the following advantages (coating on a standard 6 mm thick clear soda lime float glass sheet incorporated in a double glazing unit with another standard 4 mm thick clear soda lime float glass sheet, the space between the 15 mm glass sheets is filled 90% with argon and the stack of layers is in position 2): a. A low solar heat gain coefficient SF < 30%, preferably SF ≦ 28%, to allow for a reduction in the risk of excessive overheating as a result of insolation; b. For dual laser units, the value U≦1.1W / (m 2 K), preferably U≦1.0W / (m 2 K) the insulating properties that allow c. Neutrality of color in transmission and reflection, independent of whether in single glazing or in multiple glazing, with preferred values ​​in single glazing; 1. In transmission, 76≦L * ≦86, 12≦a * ≦-2, -2≦b * ≦8, preferably 80≦L * ≦82, -8≦a * ≦-6, 2≦b * ≦4, 2. In reflection from the substrate side of the coated substrate, 38≦L * ≦48, -8≦a * ≦2, -15≦b * ≦-5, preferably 42≦L * ≦44, -4≦a * ≦-2, -11≦b * <=-9.

[0028] The inventors have found that, among other things, it is not only beneficial to include a bottom layer comprising a metal oxide in direct contact with the substrate (and not comprising a nitride such as aluminum nitride or silicon nitride, as in many known coating stacks), in order to ensure, in particular, the chemical stability of the heat-treated or not yet heat-treated product.

[0029] Description of the embodiments FIG. 1 shows a transparent substrate (1), a lower layer (2) comprising a metal oxide in direct contact with the substrate (1), a contact layer C1 (3) comprising zinc oxide underneath and in contact with an upper first functional layer Ag1 (4), a contact layer C2 (5) comprising zinc oxide on top of and in contact with the lower first functional layer Ag1 (4), and a first layer (6) comprising a mixed oxide of zinc ZSO1 and above and in contact with C2 (5). The first layer includes a silicon nitride SiN1 (7) inserted in a first layer (6) including a mixed oxide of zinc and tin ZSO1, a contact layer C3 (8) including zinc oxide that is located directly below the first layer (6) including a mixed oxide of zinc and tin ZSO1 and in contact with a second functional layer Ag2 (9) located above it, a contact layer C4 (10) including zinc oxide that is located directly above the second functional layer Ag2 (9) located below it, and a contact layer C4 (10) above C4 (10). a second layer (11) containing a mixed oxide of zinc and tin ZSO2 and in contact with it, the second layer containing silicon nitride SiN2 (12) being inserted in the second layer (11) containing a mixed oxide of zinc and tin ZSO2; a contact layer C5 (13) containing zinc oxide and located directly below and in contact with the third functional layer Ag3 (14) located at the top; and a contact layer C5 (14) containing zinc oxide and located directly above and in contact with the third functional layer Ag3 (14) located at the bottom. Shown is a contact layer C6 (15), a third layer (16) comprising a mixed oxide of zinc and tin ZSO3 above and in contact with C6 (15), a third layer comprising silicon nitride SiN3 (17) above and in contact with the third layer comprising mixed oxide of zinc and tin ZSO3 (16), and a top layer TL (18) comprising a metal oxide or metal nitride above and in contact with the third layer comprising silicon nitride SiN3 (17).

[0030] FIG. 2 shows, in addition to the layers depicted in FIG. 1, optional layers ABS1 (18) and ABS2 (19) of absorbing material inserted in layers SiN1 (7) and SiN2 (12), respectively.

[0031] Figure 3 shows, in addition to the layers depicted in Figure 1, optional intermediate layers IL1 (20) and IL2 (21), where IL1 (20) is shown inserted within ZSO1 (6) above and not in contact with SiN (7), and IL2 (21) is shown above and in contact with ZSO2 (11).

[0032] According to one embodiment of the present invention, one, two or three of the functional layers Ag1, Ag2, Ag3 comprise or consist essentially of silver.

[0033] According to one embodiment of the present invention, one, two or three of the functional layers Ag1, Ag2, Ag3 comprise or consist essentially of silver doped with palladium.

[0034] According to one embodiment of the present invention, the transparent substrate is made of glass. The glass matrix composition is not particularly limited and therefore can belong to different glass categories. The glass can be soda-lime silicate glass, aluminosilicate glass, alkali-free glass, borosilicate glass, etc. Preferably, the glass sheet of the present invention is made of soda-lime glass or borosilicate glass.

[0035] According to one advantageous embodiment of the invention, which can be combined with the previous embodiments, the glass sheet contains 0.002 to 0.06% by weight of (Fe 2 O 3 The composition has a total iron content of 0.06% by weight or less (expressed in terms of Fe 2 O 3 The total iron content (expressed in the form of Fe 0.002-0.04 wt. %) makes it possible to obtain glass sheets having almost no visible coloration. Preferably, the composition has a total iron content in the range of 0.002-0.04 wt. % (Fe 2 O 3 More preferably, the composition has a total iron content in the range of 0.002 to 0.02 wt.% (Fe 2 O3 In the most preferred embodiment, the composition has a total iron content in the range of 0.002 to 0.015 wt.% (Fe 2 O 3 The total iron content is expressed in the form

[0036] According to a preferred embodiment, the transparent substrate of the present invention is a float glass sheet. The transparent substrate, for example, the glass sheet, according to the present invention can have a thickness of 0.1 to 25 mm.

[0037] According to one embodiment of the present invention, the stack of thin layers of the present invention comprises a layer of an absorbing material for absorbing solar radiation, which may be inserted into the first and / or second layer containing silicon nitride. In particular, the layer of absorbing material ABS1 may be inserted into the first layer containing silicon nitride SiN1 and / or the layer of absorbing material ABS2 may be inserted into the second layer containing silicon nitride SiN2, which means that the lower part of the individual silicon nitride containing layer is below and in contact with the individual layer of absorbing material, and the upper part of the individual silicon nitride containing layer is above and in contact with the individual layer of absorbing material. In other words, the layer of absorbing material ABS1 is between and in contact with two sublayers of the first layer containing silicon nitride SiN1, namely the lower sublayer SiN1a and the upper sublayer SiN1b. Similarly, the layer of absorbing material ABS2 is between and in contact with two sublayers of the second layer containing silicon nitride, namely the lower sublayer SiN2a and the upper sublayer SiN2b.

[0038] The layer of absorbing material helps to reduce the visible light transmission of the layer stack. Inserting the absorbing layer between the silicon nitride layers prevents them from being oxidized during the deposition of the subsequent layers and during tempering. Advantageously, a layer of absorbing material ABS1 inserted in a first layer containing silicon nitride SiN1 results in a relatively lower reflectance value on the inside of the building than a similar layer of absorbing material ABS2 inserted in a second layer containing silicon nitride SiN2. This has been evaluated on a double glazing unit with another standard 4 mm thick clear soda lime float glass sheet, with the space between the 15 mm glass sheets filled to 90% with argon and the layer stack in position 2.

[0039] According to an embodiment of the invention, the layer of absorbent material may in particular comprise or consist of an alloy of Ni and Cr or an alloy of Ni, Cr and W.

[0040] The absorbent material may be composed of an alloy of Ni, Cr and W, the absorbent material may contain 30% to 90% by weight, preferably 40% to 70% by weight, advantageously 45% to 65% by weight of tungsten, nickel and chromium in a nickel / chromium weight ratio of 100 / 0 to 50 / 50, preferably 80 / 20.

[0041] The absorbent material may consist of an alloy of Ni and Cr in a Ni / Cr weight ratio of 99 / 1 to 50 / 50, preferably 80 / 20.

[0042] The layers ABS1 and ABS2 comprising absorbing material may have a combined geometric thickness of at least 0.3 nm. In particular, the combined geometric thickness of ABS1 and ABS2 may be at most 3 nm.

[0043] Preferably, the layer of absorbing material is inserted only within the first layer comprising silicon nitride, which results in a lower visible light reflectance value than if the layer were inserted within the second layer comprising silicon nitride.

[0044] According to one embodiment of the present invention, D2 and / or D3 may include an intermediate layer above and not in contact with the respective silicon nitride-containing layers SiN1 and SiN2 of D2 and D3 in order to increase the chemical and / or mechanical resistance of the stack of thin layers. The intermediate layer material includes a zinc- and tin-free metal oxide or mixed metal oxide. In a.D2, the first intermediate layer IL1 may be any of the following: 1. inserted between and in contact with the contact layer C3 and the first layer containing a mixed oxide of zinc and tin ZSO1, or 2. It is inserted in a first layer containing a mixed oxide of zinc and tin ZSO1. This means that the sublayer ZSO1b is separated in two parts. One part of ZSO1b is below and in contact with IL1, and another part of ZSO1b is above and in contact with IL1. In other words, IL1 is between the two sublayers of ZSO1b, namely the lower sublayer ZSO1ba and the upper sublayer ZSO1bb. In b.D3, the second intermediate layer IL2 may be any of the following: 1. inserted between and in contact with the contact layer C5 and a second layer containing a mixed oxide of zinc and tin ZSO2, or 2. It is inserted in a second layer containing a mixed oxide of zinc and tin ZSO2. This means that the sublayer ZSO2b is separated in two parts. One part of ZSO2b is below and in contact with IL2, and another part of ZSO2b is above and in contact with IL2. In other words, IL2 is between the two sublayers of ZSO2b, namely the lower sublayer ZSO2ba and the upper sublayer ZSO2bb.

[0045] The inventors have found that these intermediate layers can further increase the chemical and / or mechanical durability of the layer stack.

[0046] Optional intermediate layer materials may include titanium oxide, a mixed oxide of titanium and zirconium, a mixed oxide of nickel and chromium, or a mixed oxide of nickel, chromium, and tungsten, among others.

[0047] The optional intermediate layer material may in particular comprise a mixed oxide of titanium and zirconium having a weight ratio of TiO2 / ZrO2 of 55 / 45 to 75 / 25, preferably 60 / 40 to 70 / 30.

[0048] The intermediate layers IL1 and IL2 each may have a geometric thickness of 1 to 5 nm, preferably 1 to 3 nm.

[0049] It is to be noted that the invention relates to all possible combinations of the features recited in the claims.

[0050] The individual layers of the stack of layers of the invention are preferably deposited by magnetron sputtering. Metal or metal alloy layers are usually deposited in an inert gas atmosphere from a metal or metal alloy sputtering target. Oxide layers are usually deposited from a metal, metal alloy or silicon target in an atmosphere containing oxygen, usually mixed with an inert gas, such as argon or krypton. Alternatively, oxide layers can be deposited from a ceramic oxide target in an inert gas atmosphere, possibly containing oxygen. Nitride layers are usually deposited from a metal, metal alloy or silicon sputtering target in an atmosphere containing nitrogen, usually mixed with an inert gas, such as argon or krypton.

[0051] The materials of the contact layers C1 to C6 comprising zinc oxide, which are located below or above the functional layer in the stack of layers of the invention, can be independently selected from any of the following: a. zinc oxide doped with aluminum in a weight ratio of Zn / Al of at least 95 / 5, preferably at least 98 / 2; b. Pure ZnO (denoted as iZnO); c. Zinc oxide (denoted as AZO) doped with aluminum in a proportion of up to 10% by weight, or alternatively up to 5% by weight, preferably about 2% by weight.

[0052] These types of contact layers have the advantage of reducing the change in optical properties, especially color and transmittance, upon thermal treatment. In particular, metal-based contact layers exhibit a relatively high degree of change in optical properties upon thermal treatment and require careful control of the deposition of the overlying oxide and nitride layers, since they result in different degrees of oxidation / nitridation of any underlying metal layer. These zinc oxide-based contact layers also provide a relatively controlled growth of the overlying functional layer, thereby reducing the thickness of the functional layer required to reach the desired degree of emissivity.

[0053] The contact layer can be obtained by sputtering from a metallic target of silicon, optionally doped with aluminum, in an oxygen-containing atmosphere, or alternatively, by sputtering from a ceramic target of zinc oxide, doped with aluminum, in a non-oxidizing atmosphere, which is preferred when depositing the contact layer on a silver layer.

[0054] According to one embodiment of the invention, the thickness of the contact layer comprising zinc oxide is preferably at most 10 nm, more preferably at most 8 nm, possibly even more preferably at most 6 nm.

[0055] According to one embodiment of the present invention, the thickness of the contact layer comprising zinc oxide is preferably at least 2 nm, more preferably at least 3 nm.

[0056] According to one embodiment of the present invention, the sum of the thicknesses of D1, D2, D3 and D4 is less than or equal to 220 nm, preferably less than or equal to 215 nm, and more preferably less than or equal to 212 nm.

[0057] According to one embodiment of the present invention, the sum of the thicknesses of D1, D2, D3 and D4 is at least 150 nm, preferably at least 170 nm, and more preferably at least 180 nm.

[0058] According to one embodiment of the present invention, the thickness of D1 is 30 to 50 nm.

[0059] According to one embodiment of the present invention, the thickness of D2 is 65 to 85 nm, preferably 70 to 80 nm.

[0060] According to one embodiment of the present invention, the thickness of D3 is 50 to 70 nm, preferably 55 to 65 nm.

[0061] According to one embodiment of the present invention, the thickness of D4 is 25 to 45 nm, preferably 30 to 40 nm, and more preferably 32 to 40 nm.

[0062] Preferably, the thickness of D2 is greater than the thicknesses of D1, D3, and D4.

[0063] Preferably, the thickness of D3 is greater than the thicknesses of D1 and D4.

[0064] Preferably, the ratio of the thickness of D1 to the thickness of D4 is from 0.8 to 1.4.

[0065] According to one embodiment of the present invention

[0066] According to one embodiment of the present invention, the thickness of Ag1, Ag2, and Ag3 is 10 to 16 nm, respectively.

[0067] According to an advantageous embodiment of the invention, the thickness of Ag1 is between 12 and 18 nm, more advantageously between 13 and 14 nm.

[0068] According to an advantageous embodiment of the invention, the thickness of Ag2 is between 10 and 17 nm, between 12 and 17 nm, between 12 and 16 nm, or between 14 and 16 nm, or alternatively between 10 and 15 nm, and even more advantageously between 11 and 13 nm.

[0069] According to one advantageous embodiment of the invention, the thickness of Ag3 is between 11 and 18 nm, advantageously between 12 and 17 nm, and even more advantageously between 13 and 15.5 nm.

[0070] Advantageously, the ratio of the thickness of Ag1 to the thickness of Ag3 is between 0.8 and 1.2.

[0071] Advantageously, the thickness of Ag2 is smaller than the thicknesses of Ag1 and Ag3.

[0072] D1 comprises a bottom layer BL comprising a metal oxide in direct contact with the substrate and a contact layer C1 comprising zinc oxide underneath and in contact with the overlying functional layer. Advantageously, the bottom layer BL is in direct contact with the contact layer C1 comprising zinc oxide.

[0073] In one advantageous embodiment of the invention, the bottom layer BL comprising a metal oxide in D1 is a layer of an oxide of at least one element selected from Zn, Sn, Ti and Zr.

[0074] In a preferred embodiment of the present invention, the BL is preferably a layer of zinc-tin mixed oxide, more preferably a layer of zinc-tin mixed oxide, in which the zinc-tin ratio is close to 50-50% by weight, such as, for example, 52-48% by weight (Zn 2 SnO 4 ) Zinc-tin mixed oxide is, for example, SiO 2 Or Al 2 O 3and / or may have good stability comparable to, for example, pure ZnO or bismuth oxide, and may also have a relatively low tendency to form haze after heat treatment of the stack, for example, comparable to the oxides of Ti or Zr.

[0075] In an advantageous embodiment of the invention, the BL has a thickness of at least 15 nm, preferably at least 20 nm. These minimum thickness values ​​allow in particular to guarantee the chemical stability of the non-heat-treated product, but also to guarantee resistance to heat treatment.

[0076] According to one preferred embodiment of the invention, the BL has a thickness of at least 30 nm, more preferably at least 35 nm. Furthermore, its thickness may preferably be at most 50 nm, more preferably at most 40 nm.

[0077] As the topmost layer of D1, directly beneath and in contact with the functional layer Ag1, contact layer C1 comprising zinc oxide is often referred to as a "nucleation" or "wetting" layer, which aids in the growth of the silver above it and helps increase the resistivity / squareness of the product.

[0078] In one embodiment of the invention, this zinc oxide-based layer C1 consists of zinc oxide or alternatively is doped with other metals, for example aluminum, typically in a proportion of up to 10% by weight, preferably about 2% by weight.

[0079] In one embodiment of the present invention, C1 has a thickness of up to 15 nm, preferably in the range of 1.5 to 10 nm, more preferably 3 to 10 nm.

[0080] D1 does not have silicon nitride.

[0081] In D2, D3 and D4, any of the first, second and third silicon nitride-containing layers are not necessarily stoichiometric and may contain other elements. The silicon nitride-containing layers in the layer stack of the present invention can prevent oxygen from migrating through the layer stack towards the functional layer, especially during heat treatment.

[0082] In one embodiment of the present invention, these silicon nitride containing layers are Si 3 N 4 , the atomic ratio Si / N is in the range of 0.6 to 0.9, preferably 0.7 to 0.8. x N y , a mixed nitride of silicon and zirconium having a weight ratio of Si / Zr in the range of 70 / 30 to 50 / 50, preferably 65 / 35 to 55 / 45.

[0083] In a preferred embodiment of the present invention, any of the first, second and third silicon nitride containing layers in D2, D3 and D4 are preferably stoichiometric Si 3 N 4 i.e., it comprises silicon and nitrogen in an atomic ratio Si / N of at least 0.72 and at most 0.78, preferably the atomic ratio Si / N is at least 0.74 and at most 0.76, which provides low visible absorption and, in addition, reduces the amount of color change upon heat treatment compared to SixNy, which is further away from stoichiometry.

[0084] According to one embodiment of the present invention, the thickness of the layers comprising silicon nitride is at least 15 nm, advantageously at least 20 nm. Such a minimum thickness may be necessary to provide the beneficial effect of these layers.

[0085] According to one embodiment of the invention, the thickness of any of the layers containing silicon nitride is at most 40 nm, advantageously at most 35 nm. Such a thickness may be necessary, especially due to the presence of three layers containing silicon nitride present in the layer stack, in order to limit internal stresses in these layers that may lead to a deterioration of the mechanical and / or chemical durability.

[0086] In one embodiment of the present invention, in D2, D3 and D4, any of the first, second and third layers comprising mixed oxides of zinc and tin comprise mixed oxides of zinc and tin, where the weight ratio of zinc to tin, Zn / Sn, is in the range of 1 / 9 to 9 / 1. Advantageously, the zinc-tin ratio is close to 50-50% by weight, for example 52-48% by weight, and for example Zn 2 SnO 4 It is composed of:

[0087] According to one embodiment of the invention, in D2, D3 and D4, any one or more of the first, second and third layers comprising a mixed oxide of zinc and tin have a thickness of at least 10 nm, more preferably at least 20 nm, preferably at most 50 nm, more preferably at most 45 nm.

[0088] According to a preferred embodiment of the invention, in D2, the first layer comprising a mixed oxide of zinc and tin ZSO1 has a thickness of at least 20 nm, more preferably at least 25 nm. Furthermore, its thickness may be at most 55 nm, preferably at most 50 nm, or alternatively at most 45 nm.

[0089] According to a preferred embodiment of the invention, in D3, the second layer comprising a mixed oxide of zinc and tin ZSO2 has a thickness of at least 10 nm, more preferably at least 15 nm. Furthermore, its thickness may preferably be at most 45 nm, preferably at most 40 nm.

[0090] According to a preferred embodiment of the invention, in D4, the third layer comprising a mixed oxide of zinc and tin ZSO3 has a thickness of at least 1 nm, more preferably at least 3 nm.Furthermore, its thickness may preferably be at most 12 nm, more preferably at most 10 nm, and in some cases more preferably at most 8 nm.

[0091] According to a preferred embodiment of the invention, in D2, a first silicon nitride layer SiN1 is inserted within the first layer comprising a mixed oxide of zinc and tin ZSO1 such that at least 10 nm of the respective mixed oxide layer is below the nitride layer and at least 10 nm of the mixed oxide layer is above the nitride layer.

[0092] According to a preferred embodiment of the invention, in D3, a second silicon nitride layer SiN2 is inserted within the second layer comprising a mixed oxide of zinc and tin ZSO2 such that at least 10 nm of the respective mixed oxide layer is below the nitride layer and at least 10 nm of the mixed oxide layer is above the nitride layer.

[0093] While zinc tin oxide is interesting for its high deposition rate, the insertion of a layer containing silicon nitride in a layer containing zinc tin oxide creates a layer alternation that limits the thickness of each layer or sublayer. The inventors believe that this may contribute on the one hand to preventing defects occurring during the growth of the layer and / or limit the build-up of thickness-dependent internal stresses as the layers become relatively thick. Furthermore, this reduces the overall amount of oxygen in the layer stack, thereby reducing the risk of oxidation of the silver layer, especially during heat treatments such as tempering. Limiting the sum of the thicknesses of D1, D2, D3, and D4 further reduces the overall amount of oxygen in the layer stack. This layer alternation and the limiting of the dielectric thickness provide an overall relatively robust layer stack.

[0094] Moreover, it has been surprisingly found that limiting the total dielectric thickness allows the solar heat gain coefficient to be further reduced while the visible light transmittance remains high, thereby increasing selectivity.

[0095] It is a further advantage that the refractive indices in the visible wavelength range are very similar for the silicon nitride-containing layers and the zinc tin oxide layers of the layer stack of the invention. This is because the thin film material Si 3 N 4 (a) and Zn 2 SnO 4 This can be seen in Figure 4, which shows the refractive index n vs. wavelength λ [nm] in (b). Thus, deviations in the layer stack thickness within one layer can be compensated for by adjusting the thickness of adjacent layers of different composition without adversely affecting the optical properties of the entire layer stack.

[0096] When the intermediate layer IL1 or IL2 is inserted into at least one of the second or third layers comprising a mixed oxide of zinc and tin, at least 5 nm of the respective mixed oxide layer of zinc and tin is below the intermediate layer and at least 5 nm of the mixed oxide layer is above the intermediate layer.

[0097] According to one embodiment of the invention, in D4, the top layer TL comprising a metal oxide or metal nitride is a layer comprising titanium and / or zirconium or a mixed nitride of silicon and zirconium, such a layer providing in particular mechanical protection for the layer stack.

[0098] According to one embodiment of the present invention, the D4 metal oxide or metal nitride top layer is the last layer in the layer stack, being the outermost layer, although a temporary protective measure such as a removable plastic or carbon film can be provided over this last permanent layer.

[0099] In one advantageous embodiment of the invention, the top coat comprises at least TiO y and ZrO z and optionally SiO xwherein x, y, and z are in the range of 1.8 to 2.2; and wherein the top coat comprises a.8-49% titanium, b. 51-92% zirconium and c. 0-9% silicon; and d. a total of 100% metal, wherein the top coat has a thickness of 0.1-10 nm to improve durability by increasing wear resistance by at least 20%, or alternatively at least 30%, or alternatively at least 40%.

[0100] In some embodiments of the present use, compatible with other embodiments of the present invention, the above-mentioned ranges of Ti, Zr, and Si in the top coat may vary independently of each other. The amount of Ti may alternatively have a range of 10-47%, or alternatively 12-46%. The amount of Zr may alternatively have a range of 53-90%. The amount of Si may alternatively have a range of 1-8%, or alternatively 2-7%. Thus, these amounts may vary independently for each metal, with the sum being 100% of the metal, including impurities, as described above.

[0101] In one advantageous embodiment of the invention, the metal oxide or metal nitride top layer of D4 is, for example, close to 65 / 35 TiO y / ZrO z in a weight ratio of 0.1 to 0.5 wt. % of an oxide or substoichiometric oxide of at least one element selected from Ti and Zr, more preferably a titanium-zirconium mixed oxide. Such a layer can provide a particularly good chemical and / or mechanical stability of the glazing.

[0102] Trace amounts of yttrium may be present in any of the Zr-containing layers of the present layer stack.

[0103] In another advantageous embodiment of the invention, the metal oxide or metal nitride top layer of D4 is composed of a mixed nitride of silicon and zirconium. Advantageously, the mixed nitride of silicon and zirconium has an Si / Zr atomic ratio of at least 1 or at least 4. Advantageously, the mixed nitride of silicon and zirconium has an Si / Zr atomic ratio of at most 12 or at most 6.

[0104] The top layer in D4 preferably has a geometric thickness of at least 1 nm, preferably at least 1.5 nm. Its geometric thickness is at most 5 nm, advantageously at most 3 nm. Unless otherwise stated, all thicknesses in this specification are geometric thicknesses. EXAMPLES

[0105] Certain embodiments of the present invention are illustrated by the following examples.

[0106] All thicknesses in the examples are given in nm. All layers were deposited using magnetic field assisted cathode sputtering under vacuum. Table 1 shows a simplified example layer stack, in which the inserted silicon nitride layers SiN1 and SiN2 and intermediate layers IL1 and IL2 are not shown. This was performed under conditions of curing in a static oven at 670° C. for 9 minutes and 30 seconds when the thermal treatment occurred.

[0107] TIFF2024546836000002.tif109170

[0108] In Example 1, a layer of silicon nitride SiN1 and an intermediate layer IL1 of TZO are inserted in a first mixed oxide layer of zinc and tin ZSO1, resulting in the following layer sequence, starting from Ag1, in D2: ZnO:Al 3-5 nm / ZSO5 12-17 nm / SiN 25-35 nm / ZSO5 6-8 nm / TZO 1-2 nm / ZSO5 6-8 nm / ZnO:Al 3-5 nm. In this document, the character " / " denotes the boundary between adjacent layers or sublayers.

[0109] In Example 2, a layer of silicon nitride SiN1 and an intermediate layer IL1 of TZO are inserted in the first mixed oxide layer of zinc and tin ZSO1. Furthermore, an absorber layer ABS1 of NiCrW is also inserted in the first layer containing silicon nitride SiN1, resulting in the following layer sequence starting from Ag1 in D2: ZnO:Al 3-5 nm / ZSO5 12-17 nm / SiN 12-18 nm / NiCrW 0.8 nm / SiN 12-18 nm / ZSO5 6-8 nm / TZO 1-2 nm / ZSO5 6-8 nm / ZnO:Al 3-5 nm.

[0110] Furthermore, in Examples 1 and 2, a layer of silicon nitride SiN2 is inserted within the second mixed oxide layer of zinc and tin ZSO2 and an intermediate layer IL2 of TZO is inserted between ZSO2 and C5, resulting in the layer sequence, starting from Ag2, in D3 as follows: ZnO:Al 3-5 nm / ZSO5 12-17 nm / SiN 25-35 nm / ZSO5 12-17 nm / TZO 1-2 nm / ZnO:Al 3-5 nm.

[0111] In Table 2 below, SGU denotes a single glazing unit of 6 mm thick clear glass and DGU denotes a double glazing unit. As can be observed, luminous properties within the desired range are obtained. In particular, low reflectance values ​​are obtained. Here, the double glazing unit includes an outer glass sheet of 6 mm clear glass with a coating at position 2 spaced 15 mm from the inner 4 mm clear glass by a cavity filled to 90% with argon. All glass sheets are regular clear soda lime glass sheets.

[0112] The glazing according to the invention simultaneously has low emissivity and solar protection properties and low visible reflectance. Example 1 and the heat-treated Example 2 also show good results in the climate chamber test and the neutral salt spray test according to the standard EN1096-2012, with no or almost no degradation over durations of 1, 2 and possibly up to 3 days. Example 2 advantageously shows a relatively low inner light reflectance, apparently due to the presence of the ABS1 layer.

[0113] TIFF2024546836000003.tif114170

[0114] TIFF2024546836000004.tif111170

[0115] In comparative example 3, a layer of silicon nitride SiN1 is present within a first mixed oxide layer of zinc and tin ZSO1, which results in a layer sequence starting from Ag1 and within D2 of ZnO:Al 3 nm / ZSO5 21.7 nm / SiN 35 nm / ZSO5 16.7 nm / ZnO:Al 5 nm.

[0116] Furthermore, in Comparative Example 3, a layer of silicon nitride SiN2 is inserted into the second mixed oxide layer of zinc and tin ZSO2, which results in the layer sequence, starting from Ag2, in D3 as follows: ZnO:Al 3 nm / ZSO5 13.6 nm / SiN 35 nm / ZSO5 8.6 nm / ZnO:Al 5 nm.

[0117] TIFF2024546836000005.tif147170

[0118] Tables 5a and 5b detail an exemplary layer stack, with all layer thicknesses given in nm and shown in brackets.

[0119] TIFF2024546836000006.tif161170

[0120] TIFF2024546836000007.tif130170

[0121] It was found that the glazings with Coating Examples 1 and 2, among others, limit the total dielectric thickness, thereby allowing a lower solar heat gain coefficient than in the glazing with Coating Example 3. At the same time, the transmittance remains high in the glazings of Examples 1 and 2, and therefore the selectivity is also relatively high.

Claims

1. A glazing unit comprising a transparent substrate (1), the transparent substrate being provided with a stack of thin layers comprising, starting from the substrate surface, an alternating arrangement of three infrared radiation-reflecting functional layers, designated first functional layer Ag1 (4), second functional layer Ag2 (9) and third functional layer Ag3 (14), and four dielectric coatings, designated D1, D2, D3 and D4, starting from the substrate surface, so that each functional layer is surrounded by a dielectric coating, the three functional layers comprising silver, a. D1 includes a lower layer BL(2) comprising a metal oxide that does not have a layer comprising silicon nitride and is in direct contact with the substrate, and a contact layer C1(3) comprising zinc oxide that is directly below and in contact with an upper first functional layer Ag1(4); b. D2 is i. a contact layer C2(5) comprising zinc oxide directly above and in contact with the underlying first functional layer Ag1(4); ii. A first layer (6) comprising a mixed oxide of zinc and tin ZSO1 in contact with C2 (5), iii. A first layer comprising silicon nitride SiN1 (7) inserted within the first layer comprising the mixed oxide of zinc and tin ZSO1 (6); iv. A contact layer C3 (8) containing zinc oxide above the first layer (6) containing the mixed oxide of zinc and tin ZSO1 and below the second functional layer Ag2 (9) and in contact with the second functional layer Ag2 (9); Including, c. D3 is i. a contact layer C4(10) comprising zinc oxide directly above and in contact with the underlying second functional layer Ag2(9); ii. A second layer (11) comprising a mixed oxide of zinc and tin ZSO2 in contact with C4 (9), iii. A second layer comprising silicon nitride SiN2 (12) inserted within the second layer comprising the mixed oxide of zinc and tin ZSO2 (11); iv. a contact layer C5 (12) comprising zinc oxide located directly below and in contact with the upper third functional layer Ag3; Including, d. D4 is i. a contact layer C6 comprising zinc oxide directly above and in contact with the underlying third functional layer Ag3; ii. a third layer comprising a mixed oxide of zinc and tin in contact with C6, iii. a third layer comprising silicon nitride in contact with the third layer comprising a mixed oxide of zinc and tin; iv. an upper layer comprising a metal oxide or a metal nitride; The invention is characterized in that it comprises A glazing unit further characterized in that the ratio of the sum of the thicknesses of the layers comprising the mixed oxide of zinc and tin to the thickness of the silicon nitride layer decreases from D2 to D3 to D4, and the sum of the thicknesses of D1, D2, D3, and D4 is 225 nm or less.

2. 2. The glazing unit of claim 1, wherein the stack of thin layers further comprises a layer ABS1 of absorbent material inserted within the first layer comprising silicon nitride SiN1 and / or a layer ABS2 of absorbent material inserted within the second layer comprising silicon nitride SiN2.

3. 3. The glazing unit of claim 2, wherein the layer of absorbing material comprises an alloy of Ni and Cr or an alloy of Ni, Cr, and W.

4. the stack of layers further comprises a first intermediate layer IL1 in D2 and / or a second intermediate layer IL2 in D3, a. The position of IL1 is i. interposed between and in contact with the contact layer C3 and the first layer comprising a mixed oxide of zinc and tin ZSO1; and ii. inserted in the first layer comprising the zinc and tin mixed oxide ZSO1; and b. The position of IL2 is i. interposed between and in contact with the contact layer C5 and the second layer comprising a mixed oxide of zinc and tin ZSO2; and ii. inserted within the second layer comprising the zinc and tin mixed oxide ZSO2; 4. A glazing unit according to claim 1, wherein the glazing unit is selected from the group consisting of:

5. 5. The glazing unit according to claim 4, wherein the materials of IL1 and IL2 are selected from the group consisting of titanium oxide, mixed oxides of titanium and zirconium, mixed oxides of nickel and chromium, and mixed oxides of nickel, chromium, and tungsten.

6. 4. A glazing unit according to claim 1, wherein the material of the contact layers C1 to C6 is selected from the group consisting of zinc oxide doped with aluminium and pure ZnO.

7. 4. A glazing unit according to any one of claims 1 to 3, wherein the thickness of D1 is 30 to 50 nm, the thickness of D2 is 65 to 85 nm, the thickness of D3 is 50 to 70 nm, and the thickness of D4 is 25 to 45 nm.

8. A glazing unit according to any one of claims 1 to 3, wherein the thickness of D2 is greater than the thicknesses of D1, D3 and D4, and the thickness of D3 is greater than the thicknesses of D1 and D4.

9. A glazing unit according to any one of claims 1 to 3, wherein the ratio of the thickness D1 to the thickness D4 is between 0.8 and 1.

4.

10. 4. The glazing unit according to claim 1, wherein the thickness of Ag1, Ag2, and Ag3 is each 10 to 16 nm.

11. 4. A glazing unit according to claim 1, wherein the thickness of Ag1 is 12 to 18 nm, the thickness of Ag2 is 10 to 15 nm, and the thickness of Ag3 is 12 to 17 nm.

12. 4. A glazing unit according to claim 1, wherein the ratio of the thickness of Ag1 to the thickness of Ag3 is between 0.8 and 1.

2.

13. 4. A glazing unit according to claim 1, wherein the thickness of Ag2 is less than the thicknesses of Ag1 and Ag3.

14. A glazing unit as described in any one of claims 1 to 3, wherein the lower layer BL containing a metal oxide in D1 is a layer of an oxide of at least one element selected from Zn, Sn, Ti, and Zr.

15. 4. A glazing unit according to claim 1, wherein the lower layer BL comprising a metal oxide has a thickness of at least 30 nm and at most 50 nm.

16. The first, second, and third silicon nitride layers are Si ３ N ４ , Si having an atomic ratio Si / N in the range of 0.6 to 0.9 ｘ N ｙ 4. The glazing unit according to claim 1, wherein the glazing material is selected from the group consisting of mixed nitrides of silicon and zirconium having a weight ratio Si / Zr ranging from 70 / 30 to 50 / 50.

17. 4. A glazing unit according to claim 1, wherein the first, second and third layers comprising silicon nitride have a thickness of at least 15 nm and at most 40 nm.

18. 4. A glazing unit according to claim 1, wherein the first, second and third layers comprising a mixed oxide of zinc and tin comprise a mixed oxide of zinc and tin, wherein the weight ratio of zinc to tin, Zn / Sn, is in the range of 1 / 9 to 9 / 1.

19. 4. A glazing unit according to claim 1, wherein the first, second and third layers comprising a mixed oxide of zinc and tin have a thickness of at least 10 nm and at most 50 nm.

20. 4. A glazing unit according to claim 1, wherein the upper layer TL containing a metal oxide or metal nitride is a layer containing titanium and / or zirconium or a mixed nitride of silicon and zirconium.

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