FR3101344A1 - Glazing comprising a sunscreen stack and a protective coating comprising yttrium - Google Patents

Abstract

Article with sunscreen properties comprising a glass substrate, a stack of layers deposited on said substrate, said stack comprising at least one layer based on metallic niobium or based on niobium nitride and a coating and protective layer of said stack, in wherein said coating layer is a dielectric layer comprising yttrium and at least one element selected from nitrogen and oxygen, said coating layer comprising at least 30 atom% yttrium, based on the aggregate cations present in said layer.

Description

Glazing comprising an antisolar stack and a protective coating comprising yttrium.

The present invention relates to an article with sunscreen properties comprising a stack of layers giving it sunscreen properties and a protective coating to provide it with scratch and wear resistance.

The invention relates to so-called solar control insulating glazing, provided with stacks of thin layers of which at least one layer is said to be functional, that is to say that it acts on solar and/or thermal radiation essentially by reflection. and absorption of near (solar) or far (thermal) infrared radiation. The application more particularly targeted by the invention is firstly the field of building, as solar control glazing. Without departing from the scope of the invention, this glazing can also be used as vehicle glazing, such as side glasses, car roofs, rear windows.

The term “functional” or even “active” layer is therefore understood, within the meaning of the present application, to mean the layers of the stack which give the stack most of its thermal insulation properties. Most often, the stacks of thin layers fitted to the glazing give it substantially improved insulation properties, very essentially, or even exclusively, thanks to the intrinsic properties of said active layers. Said layers act on the flux of thermal infrared radiation passing through said glazing, as opposed to the other layers, generally made of dielectric material and most often mainly having the function of chemical or mechanical protection of said functional layers.

Such glazing provided with stacks of thin functional layers act on the incident solar radiation either essentially by the absorption of the incident radiation by the functional layer or layers, or essentially by reflection by these same layers.

By anti-sun, it is thus meant within the meaning of the present invention the ability of the glazing to limit the energy flow, in particular the solar infrared radiation (IRS) passing through it from the outside to the inside of the dwelling or the passenger compartment. .

In another application such as the automobile, it is sometimes sought to limit the quantity of heat entering the passenger compartment of the vehicle or the building, i.e. to limit the energy transmission of solar radiation through the glazing.

The coatings are conventionally deposited by deposition techniques of the vacuum sputtering type assisted by magnetic field of a cathode of the material or of a precursor of the material to be deposited, often called magnetron sputtering technique in the field. Such a technique is now conventionally used, in particular when the coating to be deposited consists of a more complex stack of successive layers with thicknesses of a few nanometers to a few tens of nanometers.

The most efficient stacks currently marketed to solve the above problems and deposited by magnetron sputtering techniques incorporate a silver-based metal layer operating essentially in the mode of reflection of a major part of the IR radiation ( infrared) incident. These stacks are thus mainly used as low-emissivity (or low-e) glazing for the thermal insulation of buildings. They can also be used as sunscreen for their ability to reflect the infrared part of solar radiation. These layers are however very sensitive to humidity and are therefore exclusively used in double glazing, facing 2 or 3 of them, to be protected from humidity. The stacks according to the invention do not include such layers based on silver, gold, platinum or even copper. More generally, the articles according to the invention do not contain such metals, or else in very negligible quantities, in particular in the form of unavoidable impurities.

Other glazing incorporating stacks comprising layers with an antisolar function have also been reported in the field, this time based on functional layers based on niobium, optionally partially or totally nitrided, as described for example in applications WO01/21540 , WO2009/112759 or even WO2009/150343 to which reference will be made for more details. The present invention relates to such stacks and glass articles.

In such items, scratch and wear resistance is a matter of importance. Uncoated soda-lime glass, for example, is well known for its poor scratch resistance properties. The various coatings provided on the glazing, for example those used to confer specific functionalities, must also be protected from scratching and wear.

Improving the scratch resistance of functionalized glazing is generally treated by applying a layer of protective coating. This protective layer, also called "overcoat", is generally thick from a few nanometers to a few tens of nanometers. It can be deposited on the functional stack using conventional thin-layer deposition processes, such as the cathode sputtering process already mentioned, in particular reinforced by a magnetic field, called in this case "magnetron" process.

DLC (Diamond like carbon) overcoats are for example already described as increasing the scratch resistance of glazing. However, the main disadvantage of DLCs is their intrinsic thermal instability. For this reason, DLC coatings are not suitable per se for applications requiring exposure to high temperatures such as annealing, quenching or even bending. Additional sacrificial layers must be provided to protect the DLC coating during heat treatments (WO 2005/021454, WO 2019/020485), which makes their use tedious.

External layers based on transition metal oxides, such as layers based on zirconium oxide or layers based on titanium and zirconium oxide, have also been used as protective layers (WO 2016/ 097557). These overcoats can withstand heat treatments and moderately improve the scratch resistance of glazing systems, but they generally do not achieve the scratch resistance performance of DLC coatings.

It is therefore always necessary to have a protective coating capable of improving the resistance to scratches and/or wear to a level substantially equivalent or approaching that of DLC coatings while being capable of resisting heat treatments. . The applicant has found that the protective dielectric layers based on a compound comprising yttrium, and in particular based on yttrium oxide, in addition to meeting these requirements, also offer good transparency, which is particularly advantageous for the protection of stacks of layers of glazing.

In addition, it is preferable that the addition of the protective coating does not lead to significant changes in the colors perceived in reflection and in transmission of the glazing equipped with the functional solar protection stack.

Accordingly, the present invention relates to an article with sunscreen properties comprising:

- a glass substrate,

- a stack of layers deposited on said substrate, said stack comprising at least one layer based on metallic niobium or based on niobium nitride and,

- a coating layer for the protection of said stack,

wherein said coating layer is a dielectric layer comprising yttrium and at least one element selected from nitrogen and oxygen, said coating layer comprising at least 30 atomic % yttrium, based on all of the cations present in said layer.

By cations, in a classical ionic model, we mean the atoms other than oxygen and nitrogen present in the layer and less electronegative than these two elements.

The coating layer consists of a dielectric layer comprising yttrium. As opposed to the functional layers also present in the present stacks, the expression “dielectric layer” designates for example a layer which does not have a metallic character. This expression designates in particular a layer made up of a material having an n/k ratio (n = refractive index; k = extinction coefficient) over the entire visible range (from 380 nm to 780 nm) which is equal to or greater than 5. Such materials, in their massive form devoid of impurities thus have a high resistivity, in particular a resistivity greater than 10 ¹⁰ ohm.meters (Ω.m).

The yttrium-containing dielectric layer may comprise yttrium oxide, yttrium nitride or yttrium oxynitride, and preferably consists of these constituents. In a particular embodiment, the dielectric layer comprises more than 50% by weight of yttrium oxide based on the Y ₂ O ₃ formulation, preferably more than 80% of yttrium oxide or even more than 90% of yttrium oxide, based on the Y ₂ O ₃ formulation.

The coating dielectric layer comprising yttrium and in particular that comprising yttrium oxide as described above, may comprise a minority element, generally in a proportion of between 1 and 50% of all the cations (the more often metallic elements) present in the layer, for example in an amount of between 2 and 10% of all the cations present in the layer. The dopant can in particular be chosen from transition metals and lanthanides. In a particular embodiment however, the dielectric layer comprising yttrium is free of zirconium, i.e. it comprises a negligible amount of zirconium, such as less than 1 atomic percent of zirconium.

According to the invention, the oxygen and/or the nitrogen together preferably represent more than 50 atomic % of the anions present in the coating layer comprising yttrium and preferably more than 80%, even more than 90% of the anions present in the coating layer comprising yttrium. Preferably again, said coating layer comprises only oxygen and/or nitrogen anions.

The dielectric layer based on yttrium oxide typically has a refractive index, measured at 550 nm, of 1.6 to 1.8, in particular from 1.6 to 1.7.

According to the invention, the layer(s) based on metallic niobium or based on niobium nitride may (wind) comprise more than 50 atomic % of niobium on the basis of the cations present in said layer, or even more than 75 atom of niobium and preferably more than 80%, even more than 90% of niobium, on the basis of the cations present in said layer. According to a particular embodiment of the invention, in the layer(s) based on metallic niobium or based on niobium nitride only comprises niobium cations, apart from the inevitable impurities.

Without departing from the scope of the invention, however, other cations, such as zirconium in particular, may also be present in such layers, but in a minor quantity compared to niobium, for example between 1 and 30% of the niobium atoms present. in the layer, for example in an amount of between 5 and 20% of the niobium atoms present in the layer.

According to the invention, the layer(s) based on metallic niobium or based on niobium nitride are in principle free of oxygen, which can nevertheless be present in the form of unavoidable impurities in the layer, in particular following of quenching, but in a much lower proportion to the niobium and any nitrogen present. For example, the O/Nb atomic ratio in the functional layers according to the invention is less than 0.1, or even less than 0.05.

According to still other advantageous embodiments of the present invention, which can, if necessary, be combined with each other:

- The coating layer comprises at least 50 atomic % yttrium, based on the sum of the cations present in said layer.

- The coating layer is a dielectric layer comprising yttrium oxide, yttrium nitride or yttrium oxynitride.

- The coating layer comprises at least 50% by weight of yttrium oxide, based on the Y ₂ O ₃ formulation.

- The coating layer comprises less than 5 atomic % of zirconium, preferably less than 1 atomic % of zirconium and more preferably is a dielectric layer free of zirconium.

- The dielectric layer comprising yttrium has a refractive index of 1.6 to 1.8.

- The coating layer has a thickness comprised between 1 and 100 nm, preferably comprised between 1 and 20 nm and very preferably comprised between 2 and 10 nm, or even between 3 and 8 nm.

- The coating layer comprising yttrium constitutes the outermost layer of the succession of layers covering the glass surface.

- The layer(s) based on metallic niobium or based on niobium nitride has(have) a physical thickness of between 2 and 50 nm, preferably between 5 and 30 nm.

- The stack comprises, above and below the layer or layers based on metallic niobium or based on niobium nitride, layers based on silicon nitride, preferably having a physical thickness of between 1 and 100 nm, more preferably between 5 and 50 nm.

- The functional stack comprises and preferably consists of the succession of at least the following layers, from the surface of the glass substrate a) an underlayer comprising silicon nitride, preferably with a thickness of between 1 nm and 100 nm, b) a layer based on metallic niobium or based on niobium nitride, preferably with a physical thickness of between 2 and 50 nm, preferably between 5 and 30 nm, c) an overlayer comprising silicon, preferably with a thickness between 1 nm and 100 nm. Preferably also the under-layer a) and over-layer c) comprising silicon nitride are directly in contact with the layer b) based on metallic niobium or based on niobium nitride.

- The stack comprising at least one layer based on metallic niobium or based on niobium nitride does not include layers based on silver, gold, platinum or copper.

- Said article is soaked.

The invention also relates to a method for manufacturing a coated article as defined above, said method comprising the supply of a glass substrate, the depositing of a stack of layers on said substrate; said stack comprising at least one layer based on metallic niobium or based on niobium nitride, and depositing a coating layer on top of said stack, in which the coating layer comprising yttrium and at least one element selected from nitrogen and oxygen, said coating layer comprising at least 30 atomic % yttrium, based on the cations present in said layer.

The support is preferably according to the invention a sheet of glass. It is preferably transparent, colorless (it is then a clear or extra-clear glass) or colored, for example blue, green, gray or bronze. The thickness of the support generally varies between 0.1 mm and 19 mm, preferably between 0.5 and 9 mm, in particular between 2 and 8 mm, and even between 4 and 6 mm. The support can be flat or curved.

The glass is preferably of the silico-sodo-lime type but it can also be of the borosilicate or alumino-borosilicate type. The glass substrate is preferably of the float glass type, that is to say likely to have been obtained by a process which consists in pouring the molten glass onto a bath of molten tin (“float” bath). The glass substrate can also be obtained by rolling between two rollers, a technique which notably makes it possible to print patterns on the surface of the glass. The glass substrate may be tempered glass.

By "clear glass" is meant a silico-soda-lime glass obtained by the float process which, when it is not coated with layers, has a light transmission of the order of 90%, a light reflection of the about 8% and an energy transmission of about 87%, for a thickness of 4 mm. The transmissions and reflections of light and energy are defined by standard NF EN 410. Typical clear glasses are, for example, sold under the name SGG PlaniClear by Saint-Gobain Glass France or under the name Planibel Clair by AGC Flat Glass Europe. These substrates are traditionally used in the manufacture of low-emissivity glazing.

In the context of the present invention, the terms "below" and "above", associated with the position of two elements A and B (for example a layer, but also a coating or a substrate) do not exclude not the presence of other elements between said elements A and B. In particular, when related to the position of one layer relative to another, this means that the first layer is closer to the substrate than the other . On the contrary, an element A "in direct contact" with an element B means that no other element is positioned between them. The same goes for the expressions "directly on" and "directly under". It is therefore understood that, unless otherwise indicated, other layers can be inserted between each of them.

Similarly the terms "undercoat" and "overcoat" refer to the relative position of one layer to another in the stack, the surface of the glass substrate being taken as a reference.

The coating layer generally has a thickness comprised between 1 and 50 nm, preferably between 2 and 30 nm, and preferentially between 3 and 8 nm. The functional stack is present between the substrate and the coating layer. In all cases, the coating layer is advantageously the outermost layer, that is to say the last layer in direct contact with the atmosphere, placed on the support.

The present invention also relates to a method of manufacturing a coating article as described above, comprising providing a glass substrate, depositing a stack of layers on said substrate; said stack comprising at least one layer based on metallic niobium or based on niobium nitride, and depositing a coating layer on top of said stack, in which the coating layer comprising yttrium and at least one element selected from nitrogen and oxygen, said coating layer comprising at least 30 atomic % yttrium, based on the cations present in said layer.

The coating layer can be deposited on the substrate by cathode sputtering, in particular by the magnetic field-assisted cathode sputtering process (“magnetron” process). All the layers, including those of the functional stack and the layer of the protective coating are advantageously deposited by sputtering, in particular within the same deposition unit.

The coating layer according to the present invention can withstand heat treatment. The method of the present invention can therefore include a heat treatment step after the deposition of the coating layer. The heat treatment step can be a tempering step to reinforce the substrate, in particular in the case of a glass substrate. The quenching step is generally carried out at temperatures of 550 to 750°C for a few minutes, for example 3 to 30 minutes followed by rapid cooling.

The present invention therefore also relates to a glazing comprising a coated article as described above. The glazing may preferably be single glazing (monolithic), but also multiple glazing (in particular double or triple), that is to say consisting of several sheets of glass creating a space filled with gas, curved glazing and/or or laminated. The glazing can also be tempered and/or reinforced. The coating layer according to the present invention is generally positioned on the outer faces of the glazing (either towards the inside and/or towards the outside).

The present invention and its advantages are illustrated by the following non-limiting examples.

Example 1 (comparative):

A first stack of reference layers, the structure of which is given in Table 1 below, is deposited on a Planiclear® glass substrate by magnetron sputtering according to well-known techniques, for example as described in the publications cited above.

Example 2 (comparative):

A second stack of layers identical to the first is deposited on a Planiclear® glass substrate but an outer protective layer of 5 nm TiZrOx is deposited above the stack, in accordance with the teaching of application WO 2016/097557 .

Example 3 (comparative):

A third stack of layers identical to the first is deposited on a Planiclear® glass substrate but an outer protective layer of 10 nm DLC is deposited above the stack, in accordance with the teaching of application WO 2005/021454 .

Example 4 (according to the invention):

A fourth stack of layers identical to the first is deposited on a Planiclear® glass substrate but an outer protective layer of 5 nm yttrium oxide is deposited above the stack. This layer is deposited by magnetron sputtering using a flat yttrium metal target of 210 mm×90 mm with a power of 500 W and under a pressure of 2 µbar in an atmosphere having an Ar/O2 ratio of 10/4, with a flow rate of 28 sccm.

The glazing obtained according to Examples 1, 2 and 4 are then toughened according to techniques well known in the art. The glazing according to example 3 cannot be tempered without the destruction of the protective layer of DLC.

Table 1 below shows the different constitutions and thicknesses of the layers constituting the stacks tested from the surface of the glass substrate.

Example 1 Example 2 Example 3 Example 4 Glass Glass Glass Glass S _i3 N ₄ (30 nm) Si ₃ N ₄ (30 nm) S _i3 N ₄ (30 nm) Si ₃ N ₄ (30 nm) NbN (25nm) NbN (25nm) NbN (25nm) NbN (25nm) Si ₃ N ₄ (10 nm) Si ₃ N ₄ (10 nm) Si ₃ N ₄ (10 nm) Si ₃ N ₄ (10 nm)

The scratch and wear resistance of the stacks present on the glazings of Examples 1 to 4 was measured in two different ways.

1°) Scratch resistance test: a stainless steel ball 1 mm in diameter is slid over the surface of the sample with a constant load of 1N, 3N and 5N. A single pass is made over a distance of approximately 10 mm. The abrasion resistance is evaluated according to the scratches observed under the optical microscope according to the following criteria:

-- Deep scratches and cracks;
- Scratches but shallow and cracks (Hertz crack);
+ No scratches but some cracks (Hertz crack);
++ No scratches and no or few cracks (Hertz crack).

Table 2 below shows the results observed:

Example 1 Example 2 Example 3 Example 4 1N ++ ++ ++ ++ 3N - ++ ++ ++ 5N -- - ++ +

2°) Wear resistance test: a stainless steel ball 1 mm in diameter is slid several times back and forth over the surface of the sample according to examples 1 to 4 with a constant load of 10 N. 15 passages are made over a distance of approximately 10 mm. The average coefficient of friction (µ) is recorded for each pass. For wear-resistant surfaces, the coefficient of friction is assumed to be low and constant.

The results of the wear resistance tests are presented in Table 3 below, where the values of the coefficient of friction (µ) are reported as a function of the number of round trips (n):

not Example 1 Example 2 Example 3 Example 4 2 0.45 0.20 0.15 0.10 4 0.50 0.35 0.15 0.10 8 0.60 0.45 0.15 0.10 10 0.65 0.50 0.15 0.13 15 0.65 0.55 0.15 0.20

As shown in the tables above, the yttrium oxide layer has better resistance to scratches and wear than the TiZrO _x layers and, unlike the DLC layers, can undergo a very significant quenching treatment. for this type of glazing whose functional layer is based on niobium. Such glazing is in fact most often tempered or to be tempered.

The colorimetric parameters were also measured using a spectrophotometer in the international system (L, a*, b*) in transmission (T) and in reflection (Rc) on the side of the stack. The results are reported in Table 4 below:

Example 1 Example 4 a ^* _T -1.1 -1.4 b ^* _T -5.7 -5.4 a ^* _Rc 1.1 1.6 b ^* _Rc 19.6 18.4

It can be seen from the results reported in the previous table that the application of a protective layer of yttrium oxide does not significantly modify the colors perceived in reflection and in transmission.

Claims (13)

Article with sunscreen properties comprising:
- a glass substrate,
- a stack of layers deposited on said substrate, said stack comprising at least one layer based on metallic niobium or based on niobium nitride and
- a coating layer of said stack,
wherein said coating layer is a dielectric layer comprising yttrium and at least one element selected from nitrogen and oxygen, said coating layer comprising at least 30 atomic % yttrium, based on all of the cations present in said layer. An article according to claim 1, wherein the coating layer comprises at least 50 atomic % yttrium, based on the sum of the cations present in said layer. An article according to any preceding claim, wherein the coating layer is a dielectric layer comprising yttrium oxide, yttrium nitride or yttrium oxynitride. An article according to any preceding claim, wherein the coating layer comprises at least 50% by weight yttrium oxide, based on the Y ₂ O ₃ formulation. An article according to any preceding claim, wherein the coating layer comprises less than 5 atomic % zirconium, preferably less than 1 atomic % zirconium and more preferably is a zirconium-free dielectric layer. Article according to any one of the preceding claims, in which the coating layer has a thickness comprised between 1 and 100 nm, preferably comprised between 1 and 20 nm and very preferably comprised between 2 and 10 nm, even between 3 and 8nm. Article according to any one of the preceding claims, in which the coating layer comprising yttrium constitutes the outermost layer of the succession of layers covering the glass surface. Article according to any one of the preceding claims, in which the layer or layers based on metallic niobium or based on niobium nitride have a physical thickness of between 2 and 50 nm, preferably between 5 and 30 nm. Article according to any one of the preceding claims, in which the stack comprises, above and below the layer or layers based on metallic niobium or based on niobium nitride, layers based on silicon nitride , preferably having a physical thickness between 1 and 100 nm, more preferably between 5 and 50 nm. Article according to any one of the preceding claims, in which the stack comprises or is formed by the succession of at least the following layers, starting from the surface of the glass substrate:
- an underlayer comprising silicon nitride, preferably with a thickness of between 1 nm and 100 nm,
- a layer based on metallic niobium or based on niobium nitride, preferably with a physical thickness of between 2 and 50 nm, preferably between 5 and 30 nm,
- an overlayer comprising silicon nitride, preferably with a thickness of between 1 nm and 100 nm. Article according to any one of the preceding claims, in which the stack comprising at least one layer based on metallic niobium or based on niobium nitride does not comprise layers based on silver, gold, platinum or of copper. An article according to any preceding claim wherein said article is dipped. A method of making a coated article as defined in any one of claims 1 to 12, said method comprising providing a glass substrate, depositing a stack of layers on said substrate; said stack comprising at least one layer based on metallic niobium or based on niobium nitride, and the deposition of a coating layer above said stack, the coating layer comprising yttrium and at least one selected element from nitrogen and oxygen, said coating layer comprising at least 30 atomic % yttrium, based on the cations present in said layer.