WO2023131765A1

WO2023131765A1 - Solar control glazing

Info

Publication number: WO2023131765A1
Application number: PCT/FR2023/050029
Authority: WO
Inventors: David PEYROT; Anne Lelarge; Denis Guimard
Original assignee: Saint-Gobain Glass France
Priority date: 2022-01-10
Filing date: 2023-01-10
Publication date: 2023-07-13
Also published as: FR3131741A1

Abstract

The invention relates to a multiple-glazing unit comprising at least two substrates separated by at least one gas interlayer, the substrate which forms the outer wall of the glazing comprising, on the face thereof that faces the inside, a stack of layers including at least one silver-based functional metal layer and at least two dielectric coatings, each dielectric coating comprising at least one dielectric layer, so that each functional metal layer is placed between two dielectric coatings, characterised in that the stack includes a titanium oxide-based coating having, as deposited, an oxidation gradient and being located above and in contact with a silver-based functional metal layer, wherein the portion of the coating having an oxidation gradient and in contact with the functional layer is less oxidised than the portion of that coating further away from the functional layer.

Description

Title: Solar control glazing

The invention relates to solar protection glazing. Known high-performance solar protection glazings are multiple glazings comprising at least two substrates separated by at least one spacer layer of gas. The substrate constituting the outer wall of the glazing comprises on its face facing the interior a stack of layers comprising at least one functional layer based on silver.

The silver-based functional metal layers (or silver layers) have advantageous properties of electrical conduction and reflection of infrared radiation (IR), hence their use in these so-called "solar control" glazing aimed at reducing the amount of solar energy entering a building or vehicle.

These silver layers are deposited between coatings based on dielectric materials generally comprising several dielectric layers (hereinafter “dielectric coatings”) making it possible to adjust the optical properties of the stack. These dielectric layers also make it possible to protect the silver layer from chemical or mechanical attack.

There is a strong demand for solar protection glazing combining the following properties:

- high light transmission, in particular at least 70%, 75% or even 78%,

- a low or moderate solar factor,

- low heat loss resulting in low Ug coefficients in particular 1.15 W/m ² .K, 1.10 W/m ² .K, or even 1.00 W/m ² .K.

The solar factor of the glazing "FS or g" corresponds to the ratio in % between the total energy entering the room through the glazing and the incident solar energy. The solar factor therefore measures the contribution of glazing to warming the “room”. The lower the solar factor, the lower the solar gain.

The heat loss coefficient, also called “Ug value”, expresses the heat flow per square meter of glazing caused by a temperature difference between the external environment and the interior separated by the glazing. The lower this value, the lower the losses and the better the insulation.

It is very difficult to achieve sufficiently low absorption with silver-based functional multilayer stacks. This is in particular due to the presence of at least four “metal/dielectric” interfaces which each necessarily generate absorption. Preferably, the invention is limited to stacks comprising a single functional layer based on silver because they are likely to exhibit lower light absorption values in the visible and therefore higher light transmissions. Obtaining such high light transmissions, a low solar factor and low heat losses in combination is tricky because very few modifications of the stack are possible. To obtain such low heat loss at these levels of light transmission, in particular with stacks with a single functional layer based on silver, it is necessary to reduce the emissivity of the stack without increasing the absorption or the reflection. There is therefore no great flexibility of action.

In addition, these properties must be obtained even when the stack or the substrate carrying the stack has not undergone heat treatment at high temperature. This represents a strong additional constraint in the case of glazing with high light transmission. Generally, high temperature heat treatments such as annealing, bending and/or quenching cause changes within the silver layer leading to a decrease in emissivity. In the present case, one cannot count on an improvement attributable to heat treatment.

However, it is very difficult to reduce the emissivity without reducing the light transmission. Indeed, increasing the thickness of the silver layers makes it possible to lower the emissivity but to the detriment of the light transmission.

The emissivity depends directly on the quality of the silver layers such as their crystalline state, their homogeneity and their environment. “Environment” means the nature of the layers close to the silver layer and the surface roughness of the interfaces with these layers. Another way to reduce the emissivity therefore consists in improving the quality of the silver layer by choosing a favorable environment. Emissivity and resistivity (or resistance) per square vary proportionately. Therefore, it is often possible to assess the emissivity of a material by evaluating its resistance per square.

To improve the quality of functional metal layers based on silver, it is known to use under the silver layers dielectric coatings comprising dielectric layers with stabilizing function intended to promote wetting, nucleation and crystallization of the layer. silver. Dielectric layers based on crystallized zinc oxide are notably used for this purpose. Indeed, the zinc oxide deposited by the sputtering process crystallizes without requiring additional heat treatment. The layer based on zinc oxide can therefore serve as an epitaxial growth layer for the silver layer.

Another avenue for preventing the degradation of the silver layers resides in the choice of the layer located above and in contact with the silver layer. Among the known proposals is the use of so-called blocking layers or dielectric layers based on crystallized zinc oxide. The objective is to protect the functional layers from a possible degradation during the deposition of the upper dielectric coating and/or during a heat treatment.

The blocking layers are generally based on a metal chosen from nickel, chromium, titanium, niobium, or an alloy of these various metals. The various metals or alloys mentioned can also be partially oxidized, in particular have an oxygen sub-stoichiometry (for example TiOx OR NiCrOx).

These blocking layers are very thin, normally less than 2 nm thick, and are susceptible at these thicknesses to being partially oxidized during heat treatment or during deposition of an overlying layer. In general, these blocking layers are sacrificial layers, capable of capturing oxygen coming from the atmosphere or from the substrate, thus avoiding the oxidation of the silver layer.

The use of these thin blocking layers does not make it possible to obtain sufficiently high-performance glazing having in particular a sufficiently low emissivity to obtain a combination of high light transmission and sufficiently low heat loss.

Good results in terms of resistivity have been obtained so far with a material not comprising a blocking layer and in which each dielectric coating comprises at least one layer comprising silicon. The silver layer is located in contact with two layers of crystallized zinc oxide located respectively above and below the silver layer. Materials of this type comprising the sequence ZnO/Ag/ZnO are qualified as reference material in the present application.

This solution consisting of using only layers based on crystallized zinc oxide below and above the silver does not give complete satisfaction either.

The applicant has surprisingly discovered that the use of a coating comprising an oxidation gradient based on titanium oxide located above and in contact with the functional layer based on silver, in a particular stack , overcomes these disadvantages. The solution of the invention makes it possible to achieve the required properties, namely to obtain a solar protection glazing having a high light transmission, in particular of the order of 78.5% and a low emissivity. In particular, the emissivity can be low enough to allow the lowest possible heat transfer coefficients (Ug values) to be obtained.

The invention therefore relates to a multiple glazing unit comprising at least two substrates separated by at least one spacer layer of gas, the substrate constituting the outer wall of the glazing unit comprises, on its face facing inwards, a stack of layers comprising a functional metal layer silver base and at least two dielectric coatings, each dielectric coating including at least one dielectric layer, such that each functional metal layer is disposed between two dielectric coatings, characterized in that the stack comprises a coating based on titanium oxide comprising, as deposited, an oxidation gradient, located above and in contact with the functional metallic layer based on silver , the part of the oxidation gradient coating in contact with the functional layer is less oxidized than the part of this coating further from the functional layer.

The stack comprises a coating comprising an oxidation gradient as deposited. This means that a coating with an oxidation gradient is directly deposited. The gradient is present from the deposition. The gradient is not obtained following a possible heat treatment, the deposition of an overlying layer or a possible long storage.

According to the invention, a coating based on titanium oxide comprising an oxidation gradient is based on titanium oxide over its entire thickness. This coating is in contact with the silver layer. This means that the invention excludes the depositing in contact with the silver layer of a metallic titanium layer.

The applicant has surprisingly discovered that the solution of the invention makes it possible to obtain an improvement in the resistivity with the obtaining of a gain in square resistance of at least 10%, or even 15%, even in the absence of thermal treatment. In some embodiments, the improvement in resistivity is obtained without an increase in absorption. This gain in resistivity makes it possible to achieve emissivity values sufficiently low to reach the required Ug values without increasing the thicknesses of the silver layer and therefore without lowering the light transmission.

This solution therefore makes it possible to achieve high levels of light transmission, even in the case of stacks used as deposited, i.e. without being subjected to subsequent treatment at high temperature. For these stacks, the quality of the silver layers does not make it possible to obtain resistances per square as low as in the case of quenched or laser-treated stacks. Obtaining low Ug values requires the use of thicker silver layers which prevent obtaining a sufficiently high level of light transmission. The gain in resistance per square obtained thanks to the solution of the invention makes it possible to circumvent this difficulty.

Preferably, the dielectric coating located below the silver layer comprises a layer with a high refractive index. The joint presence of the coating based on titanium oxide which has a high refractive index above the functional layer based on silver and of a high index layer below the functional layer contributes to obtaining high light transmission.

The applicant has also surprisingly discovered that the use of the coating comprising an oxidation gradient based on titanium oxide associated with a layer based on zinc oxide and particular tin contributes to obtaining the properties advantages of the invention. It seems that this layer makes it possible to reduce the residual absorption in the event of incomplete oxidation of the part farthest from the silver layer of the titanium oxide-based oxidation gradient coating. The invention combining a coating based on titanium oxide in contact with a layer of zinc and tin oxide makes it possible to obtain:

- an improvement in the resistivity with the obtaining of a square resistance gain of at least 5%, even 10% or more, for certain structures of the invention, both before and after heat treatment,

- an improvement in the mechanical properties of brush resistance before and after heat treatment.

The present invention is particularly suitable in the case of stacks with a single functional layer based on silver. The solution of the invention is also suitable in the case of stacks with several functional layers based on silver, in particular stacks with two or three functional layers.

The material according to the invention may have the following characteristics alone or in combination:

- the oxidation gradient coating comprises at least two layers of titanium oxide each comprising different proportions of oxygen,

- the oxidation gradient coating comprises a first layer deposited from a ceramic target, in particular sub-stoichiometric, in an atmosphere whose percentage by volume flow of oxygen represents between 0 and 4%, preferably 0%,

- the first layer has a thickness between 0.2 and 2 nm,

- the oxidation gradient coating comprises a second layer based on titanium oxide deposited from a ceramic target, in particular sub-stoichiometric, in an atmosphere comprising higher proportions of oxygen than that used for the first layer ,

- the second layer has a thickness between 0.2 and 30 nm,

- the stack further comprises a layer based on zinc oxide and tin comprising at least 10% by mass of tin relative to the total mass of zinc and tin, located above and in contact the layer based on titanium oxide,

- the layer based on zinc oxide and tin has a thickness:

- greater than 5 nm,

- less than 40 nm.

- the dielectric coating located above the functional layer comprises a layer comprising silicon chosen from among the layers of silicon nitride,

- the dielectric coating located below the functional layer comprises a layer based on zinc oxide located in contact with the functional layer, - the dielectric coating located below the functional layer further comprises a layer with a refractive index greater than 2.20,

- the layer with a refractive index greater than 2.20 is chosen from layers based on titanium oxide and layers based on silicon nitride and zirconium,

- the thickness of all the layers with a refractive index greater than 2.20 in the dielectric coating located below the functional layer is greater than 10 nm, greater than 15 nm, greater than 20 nm,

- the dielectric coating located above the functional layer comprises a layer based on silicon nitride and zirconium,

- the dielectric coating located below the functional layer comprises a layer based on silicon nitride and zirconium,

- it has a light transmission greater than 70%, greater than 75%, greater than 76% or greater than 78%,

- it has an ILG value of less than 1.15 W/m ² .K, less than 1.10 W/m ² .K or less than 1.00 W/m ² .K,

- the stack comprises a single functional metallic layer based on silver,

- the stack has been subjected to rapid thermal annealing,

- the stack and the substrate have been subjected to a heat treatment at a high temperature above 500°C such as quenching, annealing or bending.

The invention also relates to:

- a glazing according to the invention mounted on a vehicle or on a building, and

- the use of a glazing according to the invention as solar control glazing for the building or vehicles,

- a building, a vehicle or a device comprising a glazing according to the invention.

Throughout the description, the substrate according to the invention is considered laid horizontally. The stack of thin layers is deposited above the substrate. The meaning of the expressions “above” and “below” and “lower” and “higher” should be considered in relation to this orientation. In the absence of specific stipulation, the expressions “above” and “below” do not necessarily mean that two layers and/or coatings are arranged in contact with one another. When it is specified that a layer is deposited "in contact" with another layer or a coating, this means that there cannot be one (or more) interposed layer(s) between these two layers (or layer and coating).

All the luminous characteristics described are obtained according to the principles and methods of the European standards EN 410 relating to the determination of the luminous and solar characteristics of the glazing used in glass for construction. The method for calculating the Ug coefficient of insulating glazing is described in standard NF EN 673. Sunlight entering a building is considered to flow from the exterior to the interior.

According to the invention, the luminous characteristics are measured according to the D65 illuminant at 2° perpendicular to the material mounted in a double glazing:

- TL corresponds to the light transmission in the visible in %,

- Rext corresponds to the external light reflection in the visible in %, observer outside space side,

- Rint corresponds to the interior light reflection in the visible in %, observer on the interior space side,

- a*T and b*T correspond to the colors in transmission a* and b* in the L*a*b* system,

- a*Rext and b*Rext correspond to the colors in reflection a* and b* in the L*a*b* system, observer outside space side,

- a*Rint and b*Rint correspond to the colors in reflection a* and b* in the L*a*b* system, observer on the interior space side.

As explained previously, according to the invention the properties must be obtained even when the stack or the substrate carrying the stack has not undergone heat treatment at high temperature.

The stacks according to the invention can be used interchangeably:

- as deposited, that is to say without having been subjected to any heat treatment at high temperature, in this case neither the substrate coated with the stack, nor the stack alone, has undergone heat treatment at high temperature high,

- treated by laser radiation, in this case, only the stack undergoes heat treatment at high temperature,

- treated by annealing or quenching, in this case the substrate and the stack undergo heat treatment at high temperature.

The present invention therefore relates to the non-heat-treated coated substrate. The stack may not have undergone heat treatment at a temperature above 500°C, preferably 300°C.

The present invention also relates to the substrate coated with the heat-treated stack. The heat treatments are chosen from:

- annealing, for example rapid annealing,

- quenching and/or bending.

The material, that is to say the transparent substrate coated with the stack, may have undergone a heat treatment at high temperature. The stack and the substrate may have been subjected to a heat treatment at a high temperature such as quenching, annealing or bending. It is also possible to heat treat only the stack. In this case, the stack only may have undergone heat treatment.

In these two cases, the stack may have undergone a heat treatment at a temperature above 300°C, preferably 500°C. The heat treatment temperature (at the level of the stack) is greater than 300°C, preferably greater than 400°C, and better still greater than 500°C.

According to the invention, it is also possible to carry out rapid thermal annealing (“Rapid Thermal Process”) such as laser annealing or flash lamp annealing. Rapid thermal annealing is for example described in applications WO2008/096089 and WO2015/185848. In these cases, only the stack is subjected to heat treatment. During this type of treatment, each point of the stack is brought to a temperature of at least 300° C. while maintaining a temperature less than or equal to 150° C. at any point on the face of the substrate opposite to that on which locate the stack. This process has the advantage of only heating the stack, without significant heating of the entire substrate.

In the case of laser treatment, the coated materials can be treated using a laser line formed from laser sources such as InGaAs diode lasers or Yb:YAG disc lasers. These continuous sources emit at a wavelength between 900 and 1100 nm. The laser line has a length of the order of 3.3 m, equal to the width 1 of the substrate, and an average FWHM half-width between 45 and 100 μm.

The materials are arranged on a roller conveyor so as to scroll along an X direction, parallel to its length. The laser line is fixed and positioned above the coated surface of the substrate with its longitudinal direction Y extending perpendicularly to the running direction X of the substrate, i.e. along the width of the substrate, in extending across that width.

The position of the focal plane of the laser line is adjusted to be within the thickness of the functional coating when the substrate is positioned on the conveyor. The surface power of the laser line at the focal plane is less than 100kW/cm2. The substrate was moved under the laser line at a speed of about 8 m/min.

The stack may therefore have been subjected to rapid thermal annealing in which each point of the stack is brought to a temperature of at least 300°C while maintaining a temperature less than or equal to 150°C at any point on the face. of the substrate opposite to that on which the stack is located.

It is also possible to combine heat treatments. For example, it is possible to perform rapid thermal annealing followed by quenching.

The stack and the substrate may have been subjected to a heat treatment at a high temperature above 500°C such as quenching, annealing or bending.

The coated substrate of the stack can be bent or tempered glass. The stack is deposited by cathode sputtering assisted by a magnetic field (magnetron process). According to this advantageous embodiment, all the layers of the stack are deposited by cathodic sputtering assisted by a magnetic field.

In the absence of specific stipulation, the expressions “above” and “below” do not necessarily mean that two layers and/or coatings are arranged in contact with one another. When it is specified that a layer is deposited "in contact" with another layer or a coating, this means that there cannot be one (or more) interposed layer(s) between these two layers (or layer and coating).

Unless otherwise stated, the thicknesses referred to in this document are physical thicknesses and the layers are thin layers. By thin layer is meant a layer having a thickness of between 0.1 nm and 100 micrometers.

In the present description, unless otherwise indicated, the expression "based on", used to qualify a material or a layer as to what it or it contains, means that the mass fraction of the constituent which it or it comprises is at least 50%, in particular at least 70%, preferably at least 90%.

The stack may comprise a single functional metal layer based on silver.

The silver-based metallic functional layers comprise at least 95.0%, preferably at least 96.5% and better still at least 98.0% by weight of silver relative to the weight of the functional layer. Preferably, a silver-based functional metallic layer comprises less than 1.0% by mass of metals other than silver relative to the mass of the silver-based functional metallic layer.

The silver-based metallic functional layers have a thickness:

- greater than 5 nm, 6. nm, 7 nm, 8 nm, 9. nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm or 16 nm, and/or

- less than 25 nm, 22 nm, 20 nm, 18, nm.

Dielectric coatings include dielectric layers. By "dielectric layer" within the meaning of the present invention, it should be understood that from the point of view of its nature, the material is "non-metallic", that is to say is not a metal. In the context of the invention, this term designates a material having an n/k ratio over the entire visible wavelength range (from 380 nm to 780 nm) equal to or greater than 5. n designates the index of real refraction of the material at a given wavelength and k represents the imaginary part of the refractive index at a given wavelength; the ratio n/k being calculated at a given wavelength identical for n and for k.

The thickness of a dielectric coating corresponds to the sum of the thicknesses of the layers constituting it. Preferably, the dielectric coatings have a thickness greater than 10 nm, greater than 15 nm, between 15 and 200 nm, between 15 and 100 nm or between 15 and 70 nm.

The dielectric layers of the coatings have the following characteristics alone or in combination:

- they are deposited by cathodic sputtering assisted by a magnetic field,

- they have a thickness greater than 2 nm, preferably between 4 and 200 nm.

The dielectric layers, in addition to their optical function, can have various other functions. By way of example, mention may be made of stabilizing layers, smoothing layers, and barrier layers.

The dielectric layers are conventionally chosen from layers based on oxide, based on nitride or based on oxynitride. The oxide-based layers of one or more elements consist mainly of oxygen and very little nitrogen. The oxide-based layers include in particular at least 90% in atomic percentage of oxygen relative to the oxygen and nitrogen in said layer. The nitride-based layers consist mainly of nitrogen and very little oxygen. Nitride-based layers include at least 90% atomic percent nitrogen relative to the oxygen and nitrogen in said layer. Oxynitride layers include a mixture of oxygen and nitrogen. Layers based on silicon oxynitride comprise 10 to 90% (limits excluded) in atomic percentage of nitrogen relative to the oxygen and nitrogen in said layer.

The amounts of oxygen and nitrogen in a layer are determined in atomic percentages relative to the total amounts of oxygen and nitrogen in the layer under consideration.

The dielectric layers are conventionally chosen from:

- layers comprising silicon, aluminum and/or zirconium, optionally doped with at least one other element,

- layers based on zinc and tin oxide,

- layers based on titanium oxide,

- layers based on zinc oxide.

The stack comprises a coating comprising a titanium oxide-based oxidation gradient located above and in contact with a silver-based functional metal layer, the part of the oxidation gradient coating in contact with the functional layer is less oxidized than the part of this coating furthest from the functional layer.

According to the invention, the titanium oxide coating is described as it is deposited, that is to say before any heat treatment or before any long storage. Indeed, a heat treatment at high temperature or a long storage can generate modifications within layers or coating. These changes may include correspond to a rearrangement of the oxygen atoms within the coating making it more difficult to observe the gradient.

The oxidation gradient coating has a thickness:

- greater than 3 nm, greater than 4 nm, greater than or equal to 5 nm, greater than or equal to 8 nm, greater than or equal to 10 nm, greater than or equal to 8 nm,

- less than or equal to 30 nm, less than or equal to 25 nm, less than or equal to 20 nm, less than or equal to 15 nm, less than or equal to 10 nm, less than or equal to 8 nm.

The oxidation gradient coating may include:

- a layer of titanium oxide comprising an oxygen gradient,

- at least two layers of titanium oxide comprising different proportions of oxygen.

The layers based on titanium oxide comprise at least 50%, at least 60%, at least 70%, at least 80%, at least 95.0%, at least 96.5% and better still at least 98.0 % by mass of titanium relative to the mass of all the elements constituting the layer based on titanium oxide other than oxygen.

The layers based on titanium oxide can include or consist of elements other than titanium and oxygen. These elements can be chosen from silicon, chromium and zirconium. Preferably, the elements are chosen from zirconium.

Preferably, the layer based on titanium oxide comprises at most 35%, at most 20% or at most 10% by mass of elements other than titanium relative to the mass of all the elements constituting the layer based on titanium oxide other than oxygen.

The layers based on titanium oxide can have a thickness:

- greater than or equal to 2 nm, greater than or equal to 3 nm, greater than or equal to 4 nm, greater than or equal to 5 nm, and/or

- less than or equal to 30 nm, less than or equal to 25 nm, less than or equal to 20 nm, less than or equal to 15 nm, less than or equal to 10 nm, less than or equal to 8 nm, less than or equal to 4 nm.

The layers based on titanium oxide can be obtained:

- by sputtering,

- from a metallic titanium target or a ceramic target based on titanium oxide, preferably sub-stoichiometric.

When the titanium oxide-based layer is obtained from a metal target, the deposition atmosphere includes significant proportions of oxygen.

The layers based on titanium oxide are preferably obtained from a ceramic target of titanium oxide, preferably under stoichiometric in oxygen, in an atmosphere comprising oxygen or without oxygen. The amount of oxygen in the deposition atmosphere can be adapted according to the desired properties. According to the preferred embodiment, a layer based on titanium oxide is deposited from a ceramic target, in particular substoichiometric. The layer based on titanium oxide can be deposited from a ceramic target of TiO _x under stoichiometric, where x is a number different from the stoichiometry of the titanium oxide TiO2, that is to say different of 2 and preferably less than 2, in particular between 0.75 times and 0.99 times the normal stoichiometry of the oxide. TiOx may in particular be such that 1.5<x<1.98 or 1.5<x<1.7, or even 1.7<x<1.95.

Titanium oxide-based layers can be deposited in an atmosphere that does not contain oxygen or in a controlled atmosphere that includes oxygen.

According to the invention, the term "controlled atmosphere comprising oxygen" means an atmosphere comprising an optimized quantity of oxygen to obtain the desired properties.

The deposition atmosphere comprises a mixture of noble gases (He, Ne, Xe, Ar, Kr) and oxygen. The noble gas is preferably argon.

The following parameters are used to define the conditions for sputtering deposition:

- the deposition pressure,

- the composition of the gases in volume flow (unit sccm "standard cubic centimeter per minute").

The controlled atmosphere making it possible to obtain the advantageous effects of the invention was obtained in particular with the following parameters:

- the pressure in the deposition chamber is between 1 and 15 pbar, preferably 2 and 10 pbar or 2 and 8 pbar,

- the deposition atmosphere comprises a mixture of argon and oxygen.

The controlled atmosphere making it possible to obtain the advantageous effects of the invention was obtained with a percentage by volume flow of oxygen comprised between 0 and 20%. The maximum oxygen threshold may vary to some extent depending on, for example:

- the nature of the TiOx target, in particular its oxygen sub-stoichiometry or

- power,

- the configuration of the cathode sputtering deposition chamber (geometry, places of gas inlets, etc.

Indeed, if a low deposition power is used, the volume flow quantities of oxygen that can be used during the deposition will be lower because the TiOx is deposited more slowly and is therefore more likely to oxidize.

A person skilled in the art is able to define a satisfactory controlled atmosphere by varying these parameters to some extent. The person skilled in the art is in particular perfectly able to determine the power to be applied to the target and the volume flows of oxygen and noble gases.

For this, for a given deposition pressure, the person skilled in the art is able to make increasing additions of oxygen in order to determine the range of proportion of oxygen which makes it possible to lower the resistivity after heat treatment without harming the 'absorption.

The oxidation gradient coating may comprise at least one layer based on titanium oxide deposited from a ceramic target, in particular substoichiometric, in a controlled atmosphere comprising oxygen, preferably in a controlled atmosphere comprising oxygen. The layer based on titanium oxide can be deposited with an oxygen percentage in volume flow between 0 and 20%.

The oxidation gradient coating may comprise at least two layers of titanium oxide each comprising different proportions of oxygen, that is to say different degrees of oxidation.

In this case, the coating is obtained by depositing at least two consecutive layers based on titanium oxide. This deposition in several stages makes it possible to obtain mainly in the coating a layer of titanium oxide with a large quantity of oxygen, while protecting the functional layer based on silver from a first layer of titanium oxide weakly oxidized. The absorption of the stack before heat treatment is then greatly reduced. The oxidation gradient coating can therefore comprise a first layer deposited from a ceramic target, in particular sub-stoichiometric, in an oxygen-free atmosphere.

The oxidation gradient coating may comprise a first layer based on titanium oxide deposited from a ceramic target, in particular sub-stoichiometric, in a non-oxidizing or oxidizing atmosphere whose percentage by volume flow rate of oxygen represents between 0 and 5%, between 0 and 4%, between 0 and 3%, between 0 and 2%. This first layer based on titanium oxide is in contact with the functional layer based on silver.

The amount of oxygen in the first layer based on titanium oxide must be relatively low so as not to degrade the functional layer based on silver. For this, it is possible to use a first layer deposited from a ceramic target, in particular sub-stoichiometric, in an atmosphere without oxygen or with very little oxygen. However, using a little oxygen contributes to a better resistance to the brush test without inducing too great a penalty in absorption, especially before heat treatment.

The thickness of the first layer based on titanium oxide can be as thin as that of a standard blocking layer (<1 nm), as long as the functional layer based on silver does not prove to be degraded by the oxygen present during the deposition of the next layer based on titanium oxide, deposited with more oxygen than the first. The first layer has a thickness between 0.2 and 4 nm. The first layer can have a thickness of less than 3 nm, less than 2 nm or less than 1 nm or less than 0.5 nm.

The oxidation gradient coating comprises a second layer based on titanium oxide deposited from a ceramic target, in particular sub-stoichiometric, in an atmosphere comprising higher proportions of oxygen than that used for the first layer.

The second layer based on titanium oxide can be deposited from a metal target or a ceramic target.

The second layer based on titanium oxide can be deposited from a ceramic target, in particular under stoichiometric conditions, in an oxidizing atmosphere whose percentage of oxygen in volume flow rate represents between 1 and 15%.

The second layer based on titanium oxide has a thickness between 0.2 and 30 nm, between 2 and 20 nm or between 5 and 15 nm.

The second layer based on titanium oxide can have a thickness:

- greater than 0.5 nm, greater than 1 nm, greater than 2 nm, greater than 3 nm, greater than 4 nm, greater than 5 nm,

- less than 30 nm, less than 20 nm, less than 15 nm or less than 10 nm.

The oxidation gradient coating can also comprise a single layer of titanium oxide comprising an oxygen gradient.

A coating based on titanium oxide comprising a single layer with an oxygen gradient can be obtained:

- by sputtering,

- in an atmosphere comprising a mixture of neutral gas and oxygen, by gradually increasing the flow rates of oxygen present in the atmosphere,

In this case, the volume flow rate of oxygen in the deposition atmosphere is gradually increased as the layer based on titanium oxide is deposited. The part of the oxidation gradient coating in contact with the functional layer is less oxidized than the part of this coating further from the functional layer.

Typically, when the target is a sub-stoichiometric oxygen ceramic target, the proportions of oxygen in the deposition atmosphere can vary from 0% to 15%.

According to the invention, the layers based on titanium oxide of the gradient coating form part of a dielectric coating. This means that when determining the thickness of a dielectric coating, the thickness of these layers is taken into consideration. The gradient coating is below and in contact with a dielectric layer. The dielectric layer can be based on oxide, nitride or oxynitride of one or more elements chosen from silicon, zirconium, titanium, aluminium, tin and/or zinc. Preferably, this dielectric layer has a thickness greater than 5 nm, 8 nm, 10 nm or 15 nm.

The stack may comprise at least one layer comprising silicon. Preferably, the dielectric coating located above the silver-based functional layer may comprise a layer comprising silicon. Each dielectric coating may also include at least one layer comprising silicon.

Layers comprising silicon are extremely stable to heat treatments. For example, no migration of the constituent elements is observed. Therefore, these elements are not likely to alter the silver layer. The layers comprising silicon therefore also contribute to the non-alteration of the silver layers and therefore to obtaining a low emissivity after heat treatment.

The layers comprising silicon comprise at least 50% by mass of silicon relative to the mass of all the elements constituting the layer comprising silicon other than nitrogen and oxygen.

The layers comprising silicon can be chosen from layers based on oxide, based on nitride or based on oxynitride such as layers based on silicon oxide, layers based on silicon nitride and layers based on silicon oxynitride.

Silicon oxide based layers include at least 90% atomic percent oxygen relative to the oxygen and nitrogen in the silicon oxide based layer. The silicon nitride based layers include at least 90% atomic percent nitrogen relative to the oxygen and nitrogen in the silicon nitride based layer. The layers based on silicon oxynitride include 10 to 90% (limits excluded) in atomic percentage of nitrogen relative to the oxygen and nitrogen in the layer based on silicon oxide. Preferably, the layers based on silicon oxide are characterized by a refractive index at 550 nm, less than or equal to 1.55. Preferably, the layers based on silicon nitride are characterized by a refractive index at 550 nm, greater than or equal to 1.95.

The layers comprising silicon can comprise or consist of elements other than silicon, oxygen and nitrogen. These elements can be chosen from aluminum, boron, titanium, and zirconium. The layers comprising silicon may comprise at least 2%, at least 5% or at least 8% by mass of aluminum relative to the mass of all the elements constituting the layer comprising silicon other than oxygen and nitrogen. The layers comprising aluminum can be chosen from layers based on oxide, based on nitride or based on oxynitride such as layers based on aluminum oxide such as Al2O3, layers based on of aluminum nitride such as AIN and layers based on aluminum oxynitride such as AlOxNy.

The layers based on silicon nitride and on zirconium Si _x Zr _y N _z form part of the layers comprising silicon, in particular layers based on silicon nitride.

The refractive index of layers based on silicon nitride and zirconium increases with the increase in the proportions of zirconium in said layer.

The layers based on silicon nitride can comprise aluminum and/or zirconium. Such layers may include, in atomic proportion to the atomic proportion of Si, Zr and Al:

- 50 to 98%, 60 to 90%, 60 to 70 atomic % of silicon,

- 0 to 10%, 2 to 10 atomic % of aluminium,

- 0 to 30%, 10 to 40% or 15 to 30 atomic % of zirconium.

Preferably, the dielectric coating located above the silver layer comprises a layer comprising silicon. These layers comprising silicon have, in increasing order of preference, a thickness:

- less than or equal to 40 nm and/or

- greater than or equal to 5 nm, greater than or equal to 10 nm or greater than or equal to 15 nm.

Preferably, at least one dielectric coating comprises a layer comprising silicon chosen from layers based on silicon nitride. Preferably, the dielectric coating located above the silver-based functional layer comprises a layer comprising silicon chosen from among the layers based on silicon nitride. Each dielectric coating may comprise a layer comprising silicon chosen from layers based on silicon nitride.

Preferably, the sum of the thicknesses of all the layers comprising silicon in the dielectric coating located above the first silver-based functional metal layer can be greater than 35%, greater than 50%, of the total thickness dielectric coating.

Preferably, the sum of the thicknesses of all the layers comprising silicon based on silicon nitride in each dielectric coating located above the first functional metal layer based on silver can be greater than 35%, greater than 50% , the total thickness of the dielectric coating.

The stack may comprise a layer based on zinc oxide and tin comprising at least 10% by mass of tin relative to the total mass of zinc and tin, located above and in contact with the layer based on titanium oxide. The layer based on zinc oxide and tin comprises by mass of tin relative to the total mass of zinc and tin:

- at least 10%, at least 15%, at least 20%, at least 30%, at least 40%, at least 45%, at least 50% or at least 55%,

- at most 90%, at most 80%, at most 70%, at most 65% or at most 60% by mass of zinc. The layer based on zinc oxide and tin located in the dielectric coating above the functional layer based on silver has a thickness:

- greater than 5 nm, greater than 10 nm, greater than 15 nm, greater than 18 nm,

- less than 40 nm, less than 30 nm, less than 25 nm.

The dielectric coating above the silver layer may include:

- the gradient coating,

- a layer comprising silicon, preferably a layer based on silicon nitride or a layer based on silicon nitride and zirconium or a combination of these two layers.

The dielectric coating above the silver layer may include:

- the gradient coating,

- a layer based on zinc oxide and tin comprising at least 10% by mass of tin relative to the total mass of zinc and tin, located above and in contact with the layer based on titanium oxide,

- a layer comprising silicon, possibly located above and in contact with the layer based on zinc oxide and tin, preferably a layer based on silicon nitride or a layer based on silicon nitride and zirconium or a combination of these two layers.

The dielectric coating located below the silver layer may include a so-called stabilizing layer which reinforces the adhesion of the functional layer to the layers which surround it. The stabilizing layers are preferably layers based on zinc oxide optionally doped, for example, with aluminum. The zinc oxide is crystallized. The zinc oxide-based layer comprises, in increasing order of preference, at least 90.0%, at least 92%, at least 95%, at least 98.0% by weight of zinc relative to the weight of elements other than oxygen in the layer based on zinc oxide.

According to this embodiment, the dielectric coating located below the functional layer may also comprise a layer based on zinc oxide located directly in contact with it. Indeed, it is advantageous to have a stabilizing layer, below and in contact with a functional layer, because it facilitates the adhesion and the crystallization of the silver-based functional layer and increases its quality and its stability. . The metallic functional layer is deposited above and in contact with a layer based on zinc oxide. The zinc oxide-based layer can be deposited from a ceramic target, with or without oxygen or from a metal target. The zinc oxide layers have a thickness:

- at least 1.0 nm, at least 2.0 nm, at least 3.0 nm, at least 4.0 nm, at least 5.0 nm, at least 6.0 nm and/or

- not more than 25 nm, not more than 10 nm, not more than 8.0 nm.

The dielectric coating located below the silver layer may also comprise a layer based on zinc oxide and tin comprising at least 20% by mass of tin relative to the total mass of zinc and tin , located below and in contact with the layer based on zinc oxide.

The stack can therefore comprise one or more layers based on zinc oxide and tin comprising at least 10% by mass of tin relative to the total mass of zinc and tin, located above and contact with the layer based on titanium oxide. The layers based on zinc oxide and tin preferably comprise by mass of tin relative to the total mass of zinc and tin:

- at most 90%, at most 80%, at most 70%, at most 65% or at most 60% by mass of zinc. The layers based on zinc and tin oxide have a thickness:

- greater than 5 nm, greater than 8 nm and/or

- less than 40 nm, less than 30 nm, less than 25 nm.

Preferably, the dielectric coating located below the silver layer comprises a layer with a high refractive index. The presence of high index layers above and below the silver-based functional layer contributes to obtaining high light transmission.

Among the dielectric layers, we distinguish, according to their refractive index at 550 nm, the layers with low refractive index, the layers with intermediate refractive index and the layers with high refractive index. The low to low refractive index layers have a refractive index of less than 1.70. Layers with an intermediate refractive index have a refractive index between 1.70 and 2.2. High refractive index layers have a refractive index greater than 2.2.

The high refractive index layers can be chosen from:

- layers based on titanium oxide (n550=2.4),

- layers based on mixed titanium oxide and another component chosen from the group consisting of Zn, Zr and Sn,

- layers based on a layer of zirconium nitride (n 550 = 2.55),

- layers based on silicon nitride and zirconium (n550 nm = 2.20 - 2.40),

- layers based on a layer of zirconium oxide,

- layers based on manganese oxide MnO (n550 = 2.16), - layers based on a layer of tungsten oxide (n550 = 2.15),

- layers based on a layer of niobium oxide (n550 = 2.30),

- layers based on a layer of bismuth oxide (n 550 = 2.60).

Preferably, the layer with a high refractive index is chosen from layers based on titanium oxide and the layer based on silicon nitride and zirconium.

Preferably, the stack does not include a metallic blocking layer or one based on titanium oxide below and in contact with the functional metallic layer based on silver. In this case, the silver-based functional metallic layer is located above and in contact with a dielectric layer of the dielectric coating. Preferably, this dielectric layer is a stabilizing layer.

The dielectric coating located below the silver layer may comprise a sequence of layers, defined starting from the substrate, chosen from:

- layer based on titanium oxide (high index layer) // layer based on zinc oxide,

- layer based on silicon nitride // layer based on zinc oxide,

- layer based on silicon nitride and zirconium (high index layer) // layer based on zinc oxide,

- layer based on silicon nitride // layer based on silicon nitride and zirconium (high index layer) // layer based on zinc oxide,

- layer based on silicon nitride // layer based on titanium oxide (high index layer) // layer based on zinc oxide,

- layer based on silicon nitride and zirconium (high index layer) // layer based on titanium oxide (high index layer) // layer based on zinc oxide,

- layer based on silicon nitride // layer based on silicon nitride and zirconium // layer based on titanium oxide (high index layer) // layer based on zinc oxide,

- layer based on titanium oxide (high index layer) // layer based on zinc and tin oxide // layer based on zinc oxide,

- layer based on silicon nitride // layer based on zinc and tin oxide // layer based on zinc oxide,

- layer based on silicon nitride and zirconium (high index layer) // layer based on zinc oxide and tin // layer based on zinc oxide,

- layer based on silicon nitride // layer based on silicon nitride and zirconium (high index layer) // layer based on zinc and tin oxide // layer based on zinc oxide,

- layer based on silicon nitride // layer based on titanium oxide (high index layer) // layer based on zinc and tin oxide // layer based on zinc oxide?

- layer based on silicon nitride and zirconium // layer based on titanium oxide (high index layer) // layer based on zinc oxide and tin // layer based on titanium oxide zinc,

- layer based on silicon nitride // layer based on silicon nitride and zirconium // layer based on titanium oxide (high index layer) // layer based on zinc oxide and tin / / layer based on zinc oxide.

When the stack includes a layer of silicon nitride and a layer of silicon nitride and zirconium, these layers are different, i.e. they are not composed of the same elements in the same proportions.

The dielectric coating located above the silver layer may comprise a sequence of layers, defined starting from the substrate, chosen from:

- the oxidation gradient coating // layer based on silicon nitride,

- the oxidation gradient coating // layer based on silicon nitride and zirconium,

- the oxidation gradient coating // layer based on silicon nitride and zirconium

// layer based on silicon nitride,

- the oxidation gradient coating // layer based on zinc oxide and tin // layer based on silicon nitride,

- the oxidation gradient coating // layer based on zinc and tin oxide // layer based on silicon oxide,

- the oxidation gradient coating // layer based on zinc oxide and tin // layer based on silicon nitride and zirconium,

- the oxidation gradient coating // layer based on zinc oxide and tin // layer based on silicon nitride and zirconium // layer based on silicon nitride,

- the oxidation gradient coating // layer based on zinc oxide and tin // layer based on silicon nitride // layer based on zinc oxide and tin,

- the oxidation gradient coating // layer based on silicon nitride // layer based on silicon oxide,

- the oxidation gradient coating // layer based on zinc and tin oxide // layer based on silicon nitride // layer based on silicon oxide,

- the oxidation gradient coating // layer based on silicon nitride and zirconium // layer based on silicon nitride // layer based on silicon oxide.

The stack of thin layers can optionally include a protective layer. The protective layer is preferably the last layer of the stack, that is to say the layer farthest from the coated substrate of the stack (before heat treatment). These layers generally have a thickness of between 0.5 and 10 nm, between 1 and 5 nm, between 1 and 3 nm or between 1 and 2.5 nm. This protective layer can be chosen from a layer of titanium, zirconium, hafnium, silicon, zinc and/or tin, this or these metals being in metallic, oxidized or nitrided form. According to one embodiment, the protective layer is based on zirconium oxide and/or titanium, preferably based zirconium oxide, titanium oxide or titanium oxide and zirconium. When determining the thickness of a dielectric coating, the thickness of the protective layer is taken into account.

The transparent substrates according to the invention are preferably made of a rigid mineral material, such as glass, or organic based on polymers (or polymer).

The organic transparent substrates according to the invention can also be made of polymer, rigid or flexible. Examples of polymers suitable according to the invention include, in particular:

- polyethylene,

- polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN);

- polyacrylates such as polymethyl methacrylate (PMMA);

- polycarbonates;

- polyurethanes;

- polyamides;

- polyimides;

- fluorinated polymers such as fluoroesters such as ethylene tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluorethylene (PCTFE), ethylene chlorotrifluorethylene (ECTFE), fluorinated ethylene-propylene copolymers (FEP);

- photocrosslinkable and/or photopolymerizable resins, such as thiolene, polyurethane, urethane-acrylate, polyester-acrylate and

- polythiourethanes.

The substrate is preferably a glass or glass-ceramic sheet.

The substrate is preferably transparent, colorless (it is then a clear or extra-clear glass) or colored, for example blue, gray or bronze. The glass is preferably of the soda-lime-silico type, but it can also be of borosilicate or alumino-borosilicate type glass. According to a preferred embodiment, the substrate is made of glass, in particular silico-soda-lime or of polymeric organic material.

The substrate advantageously has at least one dimension greater than or equal to 1 m, or even 2 m and even 3 m. The thickness of the substrate generally varies between 0.5 mm and 19 mm, preferably between 0.7 and 9 mm, in particular between 2 and 8 mm, or even between 4 and 6 mm. The substrate can be flat or curved, even flexible.

The invention relates to glazing in the form of multiple glazing, in particular double glazing or triple glazing.

Double glazing has 4 faces, face 1 is outside the building and therefore constitutes the outer wall of the glazing, face 4 is inside the building and therefore constitutes the inner wall of the glazing, faces 2 and 3 being inside the double glazing. Stacking according to the invention is in front 2.

Triple glazing has 6 faces, face 1 is outside the building and therefore constitutes the outer wall of the glazing, face 6 is inside the building and therefore constitutes the inner wall of the glazing, faces 2 and 3 and 4 and 5 being inside the double glazing. The stack according to the invention can be on face 2 and/or face 5.

These glazings can be mounted on a building or a vehicle.

The following examples illustrate the invention.

Examples

I. Preparation of substrates: Stacks, deposition conditions

Stacks of thin layers defined below are deposited on clear soda-lime glass substrates with a thickness of 4 mm. In the examples of the invention:

- the functional layers are layers of silver (Ag),

- the dielectric layers are based on silicon nitride doped with aluminum (SisN4: Al), based on silicon nitride and zirconium doped with aluminum (SiZrN: Al), based on zinc oxide and tin, based on zinc oxide (ZnO).

TiOx titanium oxide layers are deposited from a TiOx ceramic target with or without oxygen in the deposition atmosphere.

The deposition conditions of the layers, which were deposited by sputtering (so-called “magnetron cathode” sputtering), are summarized in Table 1.

[Table 1]

%wt: % by weight; at%: atomic.

In all the examples, the stacks according to the invention comprise coatings based on titanium oxide (coating with oxygen gradient) comprising at least two layers of titanium oxide comprising different proportions of oxygen. The first layer is deposited in contact with the silver layer in an oxygen-free atmosphere with a thickness of 1 nanometer. This layer is therefore under-oxidized. The second base coat of titanium oxide is deposited in an atmosphere with 10% oxygen by volume flow and has a thickness of at least 5 nm. This layer is therefore more oxidized than the first.

1.1. Glazing with stacking not heat treated

The following stacks have been developed to be used as deposited, i.e. without having been subjected to any heat treatment at high temperature. Neither the substrate coated with the stack, nor the stack alone, has undergone heat treatment at high temperature.

For this first series of examples, we seek to obtain a light transmission of 78.5% and a resistance per square of 2.3 Q/n.

The table below lists the materials and the physical thicknesses in nanometers (unless otherwise indicated) of each layer or coating which constitutes the stacks according to their positions with respect to the carrier substrate of the stack.

[Table 2]

In all the tables showing the optical characteristics and performances, the characteristics were measured on a double glazing with a 4/16/4 structure: 4 mm glass / 16 mm interlayer space filled with 90% argon and 10% argon. 4 mm air/glass, the stack being positioned on face 2 (face 1 of the glazing being the outermost face of the glazing, as usual).

The square resistance Rsq, corresponding to the resistance referred to the surface, is measured by induction with a Nagy SMR-12.

The “s” selectivity corresponds to the TL/g ratio.

Glazings each comprising the stacks described above were tested.

[Table 3]

In the case of the reference stack Ref. 1 does not include a gradient coating, a light transmission of 78.5% cannot be obtained when constraining the resistivity to at least 2.3 Q/D. To reach this value of 2.3 Q/n, a layer of 17 nm of silver is necessary. However, it is not possible to achieve light transmission values greater than 76% with such thicknesses.

In the case of the glazings of the invention VI.1 a, VI.1 b and VI.1 c, comprising on face 2, a stack comprising a gradient coating based on titanium oxide, it is possible to jointly obtain a light transmission of 78.5% and resistance values per square of 2.3 Q/n. The gain in resistivity provided by the use of the thick coating based on titanium oxide makes it possible to obtain the value of 2.3 Q/n, with a thinner layer of silver. These finer thicknesses of silver make it possible to obtain high light transmission values, in particular around 78.5%.

In conclusion, in the case of a stack used "as deposited", the invention indeed makes it possible to obtain high light transmissions while maintaining sufficiently low resistivity values to achieve a low emissivity and thus a lower value of Ug . We also note the obtaining of colors in external reflection that are more neutral, i.e. less red (value of a* closer to 0).

Note that the substitution of part of the TiOx layer by silicon and zirconium nitride in each dielectric coating leads to similar results (comparison VI.1a and VI.1b).

Finally, the use of a layer of zinc oxide and tin in contact with the thick layer based on titanium oxide (VI.1c) also leads to similar results in terms of solar factor, light transmission and resistivity. However, this layer aims to reduce the residual absorption that may result from the incomplete oxidation of the TiOx. In addition, the introduction of this layer based on zinc and tin oxide improves the mechanical resistance. This is reflected in particular by improved results compared to the following tests:

- Erichsen scratch test (EST),

- Erichsen Brush Test (EBT) before and after quenching at 1000 cycles.

The Erichsen brush test (EBT) consists in subjecting various coated substrates to a certain number of cycles (1000) during which the stack covered with water is rubbed using a brush. A substrate is considered to pass the test if no mark is visible with the naked eye. The EBT test before tempering gives a good indication of the ability of the glazing to be scratched during a washing operation with water using a brush.

The Erichsen scratch test (EST) consists of applying a force to the sample, in Newtons, using a tip (Van Laar tip, steel ball). Depending on the scratch resistance of the stack, different types of scratches can be obtained: continuous, discontinuous, wide, narrow, etc.

1.2. Glazing with stacking treated by laser radiation

The following stacks have been developed for use after laser heat treatment. In this case, only the stack undergoes heat treatment at high temperature. The coated substrates were processed using a laser line formed from a disc laser. The following conditions were used:

- disc laser source: Yb:YAG,

- wavelength: 1030nm,

- width: 60pm,

- power density: 70kW/cm ² .

[Table 4]

For this series of examples, we seek to obtain a light transmission of 78.5% and the lowest possible square resistance.

[Table 5]

^For a given light transmission value, the glazings according to the invention have the lowest values of solar factor (−0.3%) and of resistance per square (1.76 vs. 2.02 Q/n). In all cases, the solution of the invention makes it possible to obtain the specifications of the glazing more easily.

Substitution of a part in thickness of the TiOx layer by silicon and zirconium nitride in each dielectric coating leads to similar results (comparison VI.2a and VI.2b).

Finally, the use of a layer of zinc oxide and tin in contact with the thick layer based on titanium oxide (VI.2c) also leads to similar results in terms of solar factor, light transmission and resistivity.

However, this layer aims to reduce the residual absorption that may result from the incomplete oxidation of the TiOx following the laser treatment.

1.3. Glazing with stack treated by toughening type heat treatment

The following stacks have been developed for use after being subjected to a quench type heat treatment. The heat treatments are carried out in a NABER oven at a temperature of 650°C for 10 minutes.

[Table 6]

For this series of examples, we seek to obtain a light transmission of 78.5% and the lowest possible square resistance of 2.3 Q/n.

[Table 7]

The glazing of the VI.3a invention has a lower solar factor (-0.5%) and a lower resistance per square (1.82 vs. 2.13Q/n) for the same level of light transmission. Equivalent results were obtained with stacks 3b and 3c comprising respectively:

- a high index layer based on silicon nitride and zirconium in the upper dielectric coating (L3b),

- a layer based on zinc oxide and tin in the upper dielectric coating (3c). For these examples according to the invention undergoing a quenching type treatment, we also observe:

- a decrease in resistivity,

- improved scratch resistance with:

- less visible scratches,

- if present, an absence of hot corrosion of the existing scratches.

The examples concerning the embodiment in which the layer of TiOx is in contact with a layer of zinc and tin oxide show that the combination of the invention allows:

- not to increase absorption after heat treatment,

- to obtain a gain in square resistance,

- to obtain good resistance to corrosion and the absence of haze,

- to obtain good resistance to the brush test after heat treatment.

Thanks to the solution of the invention combining a thin under-oxidized layer and a thicker oxidized layer, absorption is limited and therefore contributes to obtaining high light transmission.

I.4. Impact of the product characteristic by process

The following examples are intended to show that the material has different properties depending on how the titanium oxide-based coating is deposited:

- presence of a gradient in the coating as deposited,

- absence of gradient during coating deposition.

All of these examples are heat treated at elevated temperature. Consequently, examples Emp.0-1 and 0-2 may include after this heat treatment an oxidation gradient in the titanium oxide layer. However, this gradient was not present in the coating as deposited.

The square resistance Rsq, corresponding to the resistance referred to the surface, is measured by induction with a Nagy SMR-12. Square resistance and absorption Abs. were measured before heat treatment (BT) and after heat treatments at a temperature of 650°C for 10 min (AT).

The brush resistance tests were carried out after TT-EBT heat treatment. Each sample is observed after a certain number of cycles: 50, 100, 200, 300.

The Ok boxes indicate good resistance to the TT-EBT test after 300 cycles. The Nok boxes indicate poor resistance to the EBT or TTEBT test after 300 cycles. The number indicated next corresponds to the number of cycles from which the test becomes bad (Nok).

The table below shows all the results:

- Rsq, Abs after heat treatment and

- TT_EBT tests after heat treatment (“Erichsen brush test”).

To show the impact of the presence of the oxidation gradient as deposited, we can compare:

- example Emp.1-1, 1-2, 1-3, 2-1 and 2-2 comprising a coating having an oxidation gradient as deposited, and

- Examples Emp.0-1 and 0-2 comprising a layer of TiOx deposited without an oxidation gradient.

After heat treatment, the stacks according to the invention all make it possible to obtain good results in the brush test, whereas it is not for the stacks without gradient. The stacks according to the invention all make it possible to obtain better results in terms of resistivity and absorption after heat treatment.

These examples clearly show that the products obtained are different depending on the way in which the oxidation gradient coating is deposited.

Claims

1 . Multiple glazing comprising at least two substrates separated by at least one spacer layer of gas, the substrate constituting the outer wall of the glazing comprises on its face facing inwards a stack of layers comprising a functional metallic layer based on silver and least two dielectric coatings, each dielectric coating comprising at least one dielectric layer, so that each functional metal layer is placed between two dielectric coatings, characterized in that the stack comprises a coating based on titanium oxide comprising, as deposited, an oxidation gradient, located above and in contact with the silver-based functional metal layer, the part of the oxidation gradient coating in contact with the functional layer is less oxidized than the part of this coating farthest from the functional layer.

2. Glazing according to the preceding claim, characterized in that the oxidation gradient coating comprises at least two layers of titanium oxide, each comprising different proportions of oxygen.

3. Glazing according to any one of the preceding claims, characterized in that the oxidation gradient coating comprises a first layer deposited from a ceramic target, in particular substoichiometric, in an atmosphere whose percentage by volume flow of oxygen represents between 0 and 4%, preferably 0%.

4. Glazing according to one of the preceding claims, characterized in that the first layer has a thickness of between 0.2 and 2 nm.

5. Glazing according to any one of claims 2 to 4 characterized in that the oxidation gradient coating comprises a second layer based on titanium oxide deposited from a ceramic target, in particular under stoichiometric, in a atmosphere comprising higher proportions of oxygen than that used for the first layer.

6. Glazing according to claim 5 characterized in that the second layer has a thickness of between 0.2 and 30 nm.

7. Glazing according to any one of the preceding claims, characterized in that the stack further comprises a layer based on zinc oxide and tin comprising at least 10% by mass of tin relative to the total mass. of zinc and tin, located above and in contact with the layer based on titanium oxide.

8. Glazing according to the preceding claim, characterized in that the layer based on zinc oxide and tin has a thickness: - greater than 5 nm,

- less than 40 nm.

9. Glazing according to any one of the preceding claims, characterized in that the dielectric coating located above the functional layer comprises a layer comprising silicon chosen from among the layers of silicon nitride.

10. Glazing according to any one of the preceding claims, characterized in that the dielectric coating located below the functional layer comprises a layer based on zinc oxide located in contact with the functional layer.

11. Glazing according to any one of the preceding claims, characterized in that the dielectric coating located below the functional layer further comprises a layer with a refractive index at 550 nm greater than 2.20.

12. Glazing according to the preceding claim, characterized in that the layer with a refractive index greater than 2.20 is chosen from layers based on titanium oxide and layers based on silicon nitride and zirconium.

13. Glazing according to claim 11 or 12, characterized in that the thickness of all the layers with a refractive index greater than 2.20 in the dielectric coating located below the functional layer is greater than 10 nm.

14. Glazing according to any one of the preceding claims, characterized in that the dielectric coating located above the functional layer comprises a layer based on silicon nitride and zirconium.

15. Glazing according to any one of the preceding claims, characterized in that the dielectric coating located below the functional layer comprises a layer based on silicon nitride and zirconium.

16. Glazing according to any one of the preceding claims, characterized in that it has a light transmission greater than 70%, greater than 75%, greater than 76% or greater than 78%.

17. Glazing according to any one of the preceding claims, characterized in that it has an llg value of less than 1.15 W/m ² .K, less than 1.10 W/m ² .K or less than 1.00 W/m ² .K.

18. Glazing according to any one of the preceding claims, characterized in that the stack comprises a single functional metal layer based on silver.

19. Glazing according to any one of claims 1 to 18 characterized in that the stack has been subjected to rapid thermal annealing.

20. Glazing according to any one of claims 1 to 18, characterized in that the stack and the substrate have been subjected to a heat treatment at a high temperature above 500° C. such as quenching, annealing or bending.

21. Glazing according to any one of the preceding claims, characterized in that the titanium oxide-based oxidation gradient coating has a thickness greater than 5 nm and less than or equal to 30 nm.