FR3101077A1 - Insulating glazing comprising a thin chromium-based layer - Google Patents

Abstract

Transparent glass article, comprising at least one glass substrate provided on at least one of its faces with a coating consisting of a stack of thin layers, including at least one functional layer giving said article solar control properties, said coating comprising the succession of the following layers, with reference to the surface of said substrate: a first layer comprising silicon nitride, a functional layer based on metallic chromium, with a physical thickness greater than or equal to 1 nm and less than or equal to 9 nm, a second layer comprising silicon nitride, wherein said first and second layers comprising silicon nitride are directly in contact with the functional layer based on metallic chromium.

Description

TITLE

Insulating glazing comprising a thin layer based on chromium

The invention relates to so-called solar control insulating glazing, provided with stacks of thin layers, at least one of which is functional, that is to say that it acts on solar and/or thermal radiation essentially by reflection. and/or absorption of near (solar) or far (thermal) infrared radiation.

The present invention relates more particularly to coated glazing(s), in particular those intended mainly for the thermal insulation of buildings.

The term "functional" or even "active" layer(s), within the meaning of the present application, means the layer(s) of the stack which confers on the stack the essential to its thermal properties.

Most often, the stacks of thin layers fitted to the glazing give it improved solar control properties essentially by the intrinsic properties of this active layer.

Said layer acts on the flow of solar radiation passing through said glazing, as opposed to the other layers, generally made of dielectric material and essentially having the function of chemical or mechanical protection of said functional layer or adjustment of the color.

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

They are grouped under the designation of solar control glazing.

They are primarily marketed and used:

• either to essentially protect the home from solar radiation and avoid overheating, such glazing being qualified in the field of solar protection,
• or essentially to ensure thermal insulation of the dwelling and prevent heat loss, these glazing being qualified as insulating glazing.

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. .

To measure the energy insulation properties of glazing, the solar factor noted FS or g is used in the field.

In a known manner, the solar factor g is equal to the ratio of the energy passing through the glazing (i.e. entering the room) and the incident solar energy.

More specifically, it corresponds to the sum of the flux transmitted directly through the glazing and the flux absorbed by the glazing (including the stacks of layers possibly present on one of its surfaces) then possibly re-emitted towards the interior (the local).

Good thermal insulation properties thus firstly require a low resistivity of the functional layer.

However, such a property also translates into greater light absorption, which tends to substantially reduce the light transmission within the glazing.

The object of the present invention is first of all to propose a glazing provided with a stack having a good compromise between its light transmission and its thermal insulation properties.

In general, all the light characteristics presented in this description, in particular the light transmission T _L and the light reflection R _L , as well as the factor g, are obtained according to the principles and methods described in standard NF EN 410 (2011) relating to the determination of the light and energy characteristics of glazing used in glass for construction.

Ideally, such glazing must have a substantially neutral coloring both in transmission and in reflection, whether on the face of the glazing on which the stack is deposited (inner side) or on the opposite face (outer side).

The most efficient stacks marketed at the present time incorporate at least one metallic layer of the Silver type operating essentially on the mode of reflection of a major part of the incident IR (infrared) radiation.

These stacks are thus mainly used as low-emissivity (or low-e) glazing for the thermal insulation of buildings.

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.

It is thus not possible to deposit such layers on simple glazing (also called monolithic).

The stacks according to the invention do not include such layers based on silver, or else based on gold or platinum, or else in very negligible quantities, in particular in the form of unavoidable impurities.

Likewise, the functional layers, or even the stacks, of the glass articles according to the invention are free of nickel or copper.

The disadvantage of silver-based coatings is also their low mechanical resistance, which also explains their use almost exclusively in the building sector on the interior faces of multiple glazing (for example faces 2 and 3 of a double glazing).

Other metallic layers with an antisolar function have also been reported in the field, comprising functional layers of the metallic Nb or nitrided NbN type, as described for example in application WO01/21540 or in application WO2009/112759.

Within such layers, the solar radiation is this time mainly absorbed in a non-selective manner by the functional layer comprising niobium, the IR radiation (that is to say whose wavelength is between approximately 780 nm and 2500 nm) and visible radiation (whose wavelength is between approximately and 380 and 780 nm) being absorbed without distinction by the active layer.

In addition to the antisun properties, in the field of building or even automobile, it is sometimes desired a private glazing, that is to say a glazing allowing daytime vision without difficulty from the interior towards the exterior at occupants of a room, a building or a vehicle, but presenting from the outside towards the inside a mirror aspect preventing vision in this direction.

However, in night vision, that is to say when the external luminosity is greater than the internal luminosity, such glazing can have the disadvantage of presenting this same mirror effect this time from the outside towards the inside if the inner reflection is too important.

To solve such a problem, it is necessary to offer glass articles whose luminous characteristics are adapted.

In particular, the problem described above could be solved according to the invention thanks to the development of glass articles including:

• the light transmission is greater than or equal to 20%,
• the light reflection on the glass side (external face) R _Lext is greater than or equal to 25%, or even greater than or equal to 30%,
• the light reflection on the stacking side (inner face) R _Lint is less than or equal to 20%, or even less than or equal to 15%,
• the difference between the two light reflections R _Lext - R _Lint (also denoted ΔR _L in the remainder of the description) is greater than 15% or even greater than 18%, or even greater than 20%.

By stack side is meant the face of the glazing on which the stack is placed.

By glass side is meant the face of the glazing opposite to that on which the stack is placed, in principle not covered.

Within the meaning of the present invention, the terms "outer face" (or "external") and "inner face" or ("internal") refer to the position of the glazing when it equips the building or the vehicle that it crew.

Also, the glass and glazing articles according to the invention have energy insulation properties in accordance with those required in the field, in particular a solar factor g close to and preferably less than 50%, or even less than 45% or even less 40% in some configurations.

The object of the present invention is to propose a glass article making it possible to solve the technical problems described above.

More specifically, the present invention relates to a transparent glass article, comprising at least one glass substrate provided on at least one of its faces with a coating consisting of a stack of thin layers, including at least one functional layer giving said article solar control properties, said coating comprising the following succession of layers, with reference to the surface of said substrate:

• a first layer comprising silicon nitride,
• a functional layer based on metallic chromium, with a physical thickness greater than or equal to 1 nm and less than or equal to 9 nm, preferably greater than or equal to 2 nm and less than or equal to 8 nm.
• a second layer comprising silicon nitride,

wherein said first and second layers comprising silicon nitride are directly in contact with the functional layer based on metallic chromium.

According to particular and preferred embodiments of the present invention, which can be combined with each other if necessary:

- The first layer comprising silicon nitride has a thickness of between 1 and 100 nm, preferably between 10 and 80 nm.

- The second layer comprising silicon nitride has a thickness between 1 and 100 nm, preferably between 1 and 50 nm, more preferably between 2 and 25 nm.

- The first layer comprising silicon nitride is thicker than the second layer comprising silicon nitride.

- The stack does not include layers based on Ag, Au, Pt, Cu, Ni or stainless steel.

- The stack comprises a single functional layer based on metallic chromium, the thickness of the layer being between 2 and 9 nm, in particular between 3 and 8 nm.

- The stack is formed by the succession of the following layers:

SiN _x /Cr/SiN _x

wherein SiN _x denotes said layer comprising silicon nitride and Cr denotes said layer based on metallic chromium.

- The stack comprises two functional layers based on chromium, a third layer comprising silicon nitride being interposed in the stack between the two functional layers based on chromium.

- The third layer of chromium is directly in contact with the chromium-based layers, according to the following succession of layers:

SiN _x /Cr/SiN _x /Cr/SiN _x

wherein SiN _x denotes said layers comprising silicon nitride and Cr denotes said layers based on metallic chromium.

- The chromium-based functional layer or layers comprise more than 80 atomic % of chromium.

- The functional layer(s) consist essentially of chromium and preferably consist of chromium, apart from the inevitable impurities.

- The first layer comprising silicon nitride is deposited directly on the glass substrate and is in contact with the latter.

- At least one layer comprising a metal oxide is present between the surface of the glass substrate and the first layer comprising silicon nitride, the metal oxide preferably being chosen from an oxide of an element chosen from silicon, titanium, tin, zinc, aluminum, zirconium or a mixture of at least two of these elements, in particular silicon oxide, titanium oxide or an oxide of zinc and tin.

- At least one layer comprising a metal oxide is present above said succession of layers, the metal oxide preferably being chosen from an oxide of an element chosen from silicon, titanium, tin, zinc, aluminum or a mixture of at least two of these elements, in particular silicon oxide, titanium oxide, zirconium oxide or a mixture of these oxides.

- The article is heat-tempered and/or bent.

The chromium-based functional layer or layers have at least 50 atomic% chromium.

Preferably, the functional layer or layers of the stack have at least 70 atomic %, or even at least 80 atomic % of chromium, or even preferentially more than 90 atomic % of chromium.

According to a highly preferred embodiment, the functional layer or layers consist essentially of chromium and more preferably consist of chromium, apart from the inevitable impurities.

Without departing from the invention however, the functional layer(s) may comprise one or more other atoms, for example chosen from Al, Si, Mo, W, Zn, Ti, Mg, Co, Ni.

The functional layer or layers according to the invention may comprise a minimal part of nitrogen and/or oxygen, but less than 15 atomic %, or even less than 10 atomic %, or even less than 5 atomic %.

Preferably, however, the functional layer or layers according to the invention do not in principle comprise nitrogen or oxygen or else in the form of unavoidable impurities, resulting for example from a heat treatment of the glazing such as tempering or bending. .

Similarly, the functional layer or layers according to the invention do not in principle comprise any carbon or hydrogen or else in the form of unavoidable impurities.

In the layers according to the invention comprising silicon nitride, the silicon nitride preferably represents at least 50% by weight of silicon nitride, on the basis of a Si ₃ N ₄ formulation, and preferably more than 80% of silicon nitride or even more than 90% silicon nitride, based on the Si ₃ N ₄ formulation.

Said layers preferably consist essentially of silicon nitride, but may also include an element other than silicon, in particular aluminum.

Aluminum is in particular commonly used, in proportions which can go up to 15 atomic %, in the silicon targets used for the deposition by cathodic sputtering assisted by a magnetic field (magnetron) of stacks of thin layers on control glazing solar, and in particular layers based on silicon nitride.

Thus, without departing from the scope of the invention, the silicon of said layers can be substituted by elements of the Al, Zr, B, etc. type, in particular so as to modify the color in transmission and/or in reflection of the glazing, according to the techniques well known in the art and in proportions which can range up to 15 atomic %.

The coatings according to the invention are conventionally deposited by deposition techniques of the magnetic field-assisted vacuum sputtering type of a cathode of the material or of a precursor of the material to be deposited, often called the technique of magnetron sputtering in the domain.

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 or a few tens of nanometers.

The present invention also relates to a facade facing panel of the spandrel type incorporating at least one glazing as previously described or to a side window, a rear window or a roof for an automobile or other vehicle consisting of or incorporating said glazing.

According to the invention, the functional layers according to the invention make it possible to obtain a relatively high value of the light transmission of the substrate, while retaining a notable insulating effect, despite the very low thickness of the functional layer, after a heat treatment .

By the terms "undercoat" and "overcoat", reference is made in this description to the respective position of said layers relative to the functional layer(s) in the stack, said stack being supported by the glass substrate taken as a reference .

In particular, the underlayer is generally the layer in contact with the glass substrate and the overlayer is the outermost layer of the stack, facing away from the substrate.

If the application more particularly targeted by the invention is glazing for the building, it is clear that other applications are possible, in particular in the glazing of vehicles (apart from the windshield where one requires a very high light transmission), such as the side glasses, the car roof, the rear window.

The invention and its advantages are described in more detail, below, by means of the non-limiting examples below, according to the invention and comparative.

Throughout the examples and the description, the thicknesses given are physical.

All the substrates are made of clear glass 6 mm thick of the Planilux® type marketed by the company Saint-Gobain Glass France.

All the layers are deposited in a known manner by sputtering assisted by a magnetic field (often called a magnetron).

In a well-known way, the various successive layers are deposited in the successive compartments of the cathode sputtering device, each compartment being provided with a specific metal target in Si, or Cr, under conditions chosen for the deposition of a specific layer of stacking.

For example, the silicon nitride layers are deposited in a first compartment of the device from a metallic silicon target (doped with 8% by mass of aluminium), in a reactive atmosphere containing nitrogen (40% Ar and 60% N ₂ ).

The silicon nitride layers, denoted Si ₃ N ₄ therefore contain a little aluminum.

These layers are designated below according to the conventional general formulation Si ₃ N ₄ , even if the deposited layer does not necessarily correspond to this assumed stoichiometry.

The metallic chromium layers are deposited from the sputtering of a metallic Cr target in an inert atmosphere (i.e. by means of a plasma obtained from Argon gas alone) or in a plasma generated from Argon gas.

Examples 1-5:

In all the examples 1 to 5 which follow, the glass substrate has thus been covered successively with a stack of layers comprising a functional layer in chromium surrounded by a first layer (under layer) in Si ₃ N ₄ and a second layer (overlayer) of Si ₃ N ₄ .

In these examples, the stack therefore consists of a layer of chromium encapsulated by two layers of silicon nitride according to the following sequence:

Glass / Si ₃ N ₄ ( ^1st layer) /Cr /Si ₃ N ₄ ( ^2nd layer)

Different stacks are synthesized to adjust the solar factor and the light transmission to different possible configurations sought in the field of building.

Thus in example 1, the thicknesses of the different layers are configured so as to obtain a glazing with a low solar factor, while for example 5, we seek to maximize, on the contrary, the light transmission through the glazing.

The glass articles thus synthesized according to conventional techniques are then heated and quenched according to conventional techniques in the field (heating at 620°C for 10 minutes followed by quenching).

Table 1 below groups the information concerning the constitution of the solar protection stacks according to Examples 1 to 5 according to the invention:

Thickness (nm)
^1st layer Si ₃ N ₄ Thickness (nm)
CR layer Thickness (nm)
^2nd layer Si ₃ N ₄ Example 1 62 7 16 Example 2 62 5 14 Example 3 15 4 2 Example 4 45 3 3 Example 5 49 2 16

The values of light transmission T _L and of external light reflections R _ext and internal light reflections R _int are measured in the range 380 nm to 780 nm according to the methods described in standard NF EN 410 (2011).

The solar factor g is also measured according to this standard, in the range 300 nm to 2500 nm.

The results obtained are summarized in Table 2 below:

T _L R _Next R _Lint ΔR _L g Example 1 22 47 11 36 32 Example 2 28 42 8 34 38 Example 3 32 30 11 19 42 Example 4 40 34 7 27 48 Example 5 46 30 10 20 52

It can be seen that the glass articles according to examples 1 to 5 fulfill the conditions set out above for obtaining private solar protection glazing, the values of T _L and of g being able to be adjusted according to the thickness of the chromium layer .

It is also observed that the ΔR _L (R _Lext - R _Lint ) is in all cases close to 20, or even substantially greater than 20, which makes it possible to guarantee the “private” properties of such glazings, in the sense described above.

The colorimetric values in transmission, internal reflection and external reflection according to the L, a*, b* standard are reported in table 3 below:

a* _TL b* _TL a* _RLext b* _RLext a* _RLint b* _RLint Example 1 0.6 -2.3 -1.4 5.3 4.4 -0.5 Example 2 0.6 -2.7 -1.5 4.8 5.8 2.7 Example 3 1.5 -1.8 -1.4 1.1 -1.8 5.8 Example 4 0.6 -1.3 -1.1 -2.2 3.7 4.3 Example 5 0.4 -3.5 -1.3 3 1.7 7.4

We can see that the values of the coefficients a* and b* are relatively low and in all cases less than or equal to 8, which reflects a relative neutrality of the perceived color both in reflection and in transmission.

Comparative examples:

The properties of the stacks of application WO 01/21540 cited above can be compared with those of the stacks according to the invention and described above.

Example 4 of application WO01/21540 describes a stack comprising the following succession of layers:

Glass / Si ₃ N ₄ (10nm) / Nb (12 nm) / Si ₃ N ₄ (17 nm)

In the table on page 18 of this publication, it is indicated that the light transmission is 32%.

We can calculate that the solar factor g is about 36%.

The values of R _Lext and R _Lint reported in the publication are respectively equal to 14 and 25%.

If the values of the TL and g of this example according to the prior art are comparable to examples 2 or 3 reported in the previous table 2, it can be seen that the values of the external and internal reflections do not allow the obtaining of the private glazing, in the sense previously described, the ΔR _L even being negative in this configuration.

Similarly, example 6 of application WO01/21540 describes a succession of layers in the stack:

Glass / Si ₃ N ₄ (10nm) / NbN (10 nm) / Si ₃ N ₄ (15 nm)

In the table on page 18 of this publication it is indicated that the light transmission is 31%.

We can calculate that the solar factor g is about 48%.

The values of R _Lext and R _Lint reported in the publication are respectively equal to 18 and 28%.

If the values of the TL and g of this example according to the prior art are comparable to example 4 reported in the previous table 2, it can be seen that the values of the external and internal reflections do not allow the obtaining of the private glazing, in the sense previously described, the ΔR _L even being negative in this configuration.

Example 6:

In this example, a stack comprising two layers of chromium and corresponding to the following succession of layers was deposited:

Glass/Si ₃ N ₄ /Cr/ Si ₃ N ₄ /Cr/ Si ₃ N ₄

The exact compositions of the stacks are given in Table 4 below from the glass surface:

Thickness
^1st layer Si ₃ N ₄ Thickness
CR layer ₁ Thickness
Intermediate layer Si ₃ N ₄ Layer Thickness Cr ₂ Thickness
^2nd layer Si ₃ N ₄ Example 6 28 1.5 44 3 2

The optical and energy characteristics of the glass substrate are given in Table 5 below:

T _L R _Next R _Lint ΔR _L g Example 6 28 31 8 23 39

The colorimetric characteristics of the glass substrates are given in Table 6 below:

a* _TL b* _TL a* _RLext b* _RLext a* _RLint b* _RLint Example 6 2.3 -1 -0.2 2.8 3.6 1.1

The data reported in Tables 4 to 6 above show that the stacks according to the invention comprising two chromium-based layers also have a very high colorimetric neutrality.

Claims (16)

Transparent glass article, comprising at least one glass substrate provided on at least one of its faces with a coating consisting of a stack of thin layers, including at least one functional layer giving said article solar control properties, said coating comprising the succession of following layers, with reference to the surface of said substrate:

• a first layer comprising silicon nitride,
• a functional layer based on metallic chromium, with a physical thickness greater than or equal to 1 nm and less than or equal to 9 nm,
• a second layer comprising silicon nitride,

wherein said first and second layers comprising silicon nitride are directly in contact with the functional layer based on metallic chromium. Article according to claim 1, in which the first layer comprising silicon nitride has a thickness comprised between 1 and 100 nm, preferably between 10 and 80 nm. Article according to one of the preceding claims, in which the second layer comprising silicon nitride has a thickness of between 1 and 100 nm, preferably between 1 and 50 nm, more preferably between 2 and 25 nm. Article according to one of the preceding claims, in which the first layer comprising silicon nitride is thicker than the second layer comprising silicon nitride. Article according to one of the preceding claims, in which the stack does not comprise layers based on Ag, Au, Pt, Cu, Ni or stainless steel. Article according to one of the preceding claims, comprising a single functional layer based on metallic chromium. Article according to the preceding claim, in which the stack consists of the succession of the following layers:
SiN _x /Cr/SiN _x
wherein SiN _x denotes said layer comprising silicon nitride and Cr denotes said layer based on metallic chromium. Article according to one of Claims 1 to 5, characterized in that the stack comprises two functional layers based on chromium, a third layer comprising silicon nitride being interposed in the stack between the two functional layers based on chromium . Article according to the preceding claim, in the third layer of chromium is directly in contact with the chromium-based layers, according to the following succession of layers:
SiN _x /Cr/SiN _x /Cr/SiN _x
wherein SiN _x denotes said layers comprising silicon nitride and Cr denotes said layers based on metallic chromium. Article according to one of the preceding claims, in which the functional layer or layers based on chromium comprise more than 80 atomic % of chromium. Article according to one of the preceding claims, in which the functional layer or layers consist essentially of chromium and preferably consist of chromium, apart from the inevitable impurities. Article according to one of the preceding claims, in which the first layer comprising silicon nitride is deposited directly on the glass substrate and is in contact with the latter. Article according to one of Claims 1 to 11, in which at least one layer comprising a metal oxide is present between the surface of the glass substrate and the first layer comprising silicon nitride, the metal oxide preferably being chosen from an oxide of an element chosen from silicon, titanium, tin, zinc, aluminum, zirconium or a mixture of at least two of these elements, in particular silicon oxide, oxide titanium or an oxide of zinc and tin. Article according to one of the preceding claims, in which at least one layer comprising a metal oxide is present above the said succession of layers, the metal oxide preferably being chosen from an oxide of an element chosen from silicon, titanium, tin, zinc, aluminum or a mixture of at least two of these elements, in particular silicon oxide, titanium oxide, zirconium oxide or a mixture of these oxides. Article according to one of the preceding claims, characterized in that it is heat-tempered and/or curved. Facade facing panel of the spandrel type incorporating at least one article according to one of the preceding claims.