WO2018172350A1

WO2018172350A1 - Solar control glazing

Info

Publication number: WO2018172350A1
Application number: PCT/EP2018/057010
Authority: WO
Inventors: Jacques Dumont; Stijn Mahieu
Original assignee: Agc Glass Europe
Priority date: 2017-03-21
Filing date: 2018-03-20
Publication date: 2018-09-27
Also published as: MA47010A1; MA47010B1

Abstract

The invention relates to transparent solar control glazing with low light transmission, characterised by pleasing aesthetics, good durability and good resistance to heat treatments. The term pleasing aesthetics covers all aspects, whether shade or transmission, both for internal and external reflection. The glazing of the invention is characterised by the presence of a multilayer stack comprising at least two absorbents, at least one of the two of which has an essentially metal nature. In a second embodiment, the stack comprises at least two absorbents, at least one of which is metal and at least comprises either the nitride or the carbide or the boron of a metal. In all the embodiments, each absorbent is surrounded by dielectric coatings.

Description

Solar control glazing

1. Field of the invention

The field of the invention is that of transparent glazing provided with a layer system capable of imparting solar control properties, containing no silver. Such glazings can be used for monolithic glazings, multiple or laminated, in the automobile, the building or in some domestic applications.

The layer system generally comprises at least one functional layer intended to absorb and / or reflect part of the solar radiation, as well as coatings consisting of dielectrics located on either side of each functional layer.

Typically, the materials constituting the functional layer are metals such as Ni, Cr, W, Ti, Nb, Zr, Ta, Hf, V, Co, Mo, Al , and the alloys they can compose, as well as their nitrides, carbides or borides. A material may fulfill the role of absorbent within the meaning of the invention since its average extinction coefficient k, for the visible range whose wavelength ranges from 380 nm to 780 nm is greater than 0.5.

The dielectric coatings surrounding the functional layer can fulfill various roles, such as the optimization of the optical properties (light transmission, reflection, coloration, ...), the improvement of the durability and the resistance of the multilayer stack to the aggressions ( mechanical and / or chemical), protection (barrier to ion migration, oxygen barrier, etc.), support for the growth of metal layers (crystallization), improvement of resistance to heat treatments ... The dielectric coatings can be single or multiple. The constituent materials of the dielectrics generally used are chosen from oxides, nitrides and oxynitrides of metals such as In, Sn, Si, Al, Zr, Ti and mixtures thereof. Adjusting the nature and thickness of the functional and dielectric layers makes it possible to adapt the properties of the glazing according to its end use. In the case of layers for solar control, the glazing that carries it must be able to prevent heating of the interior of a vehicle cabin or a building room while maintaining a certain number of optical characteristics such as the light transmission, the internal and external reflection, the aesthetics of the glazing (shade) without neglecting the durability of the coating. Some or all of the features mentioned just before can be subject to strict national end-use regulations. With regard to the aesthetic aspect, the presence of the layer systems can cause color problems. Most often manufacturers ask that glazing offer both transmission and reflection as neutral color as possible and therefore gray or bronze appearance. Slightly green or bluish tones are also possible. The layer systems, and in particular the types, indices and thicknesses of the dielectric coatings surrounding the functional layer or layers are chosen, in particular to control these hues.

Moreover, the use of these windows in buildings or the automobile also supposes that in certain cases, they are subjected to heat treatments such as tempering for security reasons in the building or bending for shaping in the automobile. Applying the layers after the heat treatment is an approach that is technically more difficult and more expensive. The layer system is therefore preferably applied prior to the heat treatment and must then be subjected to temperature conditions that generally exceed 600 ° C for several minutes. Increasingly, end-users are demanding that the heat-treated glass shade not be distinguishable from the original hue and that in all cases the hue should be pleasant to the eye. It is therefore necessary that the layer system is able to withstand heat treatment without its mechanical or optical properties being altered. Since the metal layers are likely to be oxidized at During the heat treatment, the dielectrics surrounding the functional layer must be carefully selected to protect it in case of heat treatment.

Definitions: In the remainder of the description and for the claims,

Glass or glass substrate means an inorganic glass having a thickness greater than or equal to 0.5 mm and less than or equal to 20 mm, preferably greater than or equal to 1.5 mm and less than or equal to 15 mm, comprising silicon as one of the essential components of the vitreous material. Sodium and extra-clear silico-soda-lime glasses with a low iron content are preferred. More particularly, a clear, untinted plain float glass of 6 mm thickness is used. For such a glass, in the absence of a layer, the light transmission in the visible range is approximately 90% and the reflection at 8%.

- The visible transmission, T _v , and outward reflection properties L and the interior L are given for a D65 illuminant under 2 ° in accordance with the EN410 standard. - Unless otherwise stated, the thicknesses indicated for the layers are geometrical thicknesses and are expressed in nm.

- Unless otherwise specified, when a range of values is given, it should be understood that this range includes the indicated limit values.

- "Transparent multilayer stack" means a succession of layers comprising at least one functional layer and dielectrics surrounding the said functional layer (s), the assembly being deposited on a transparent substrate , which substrate has, with its multilayer stack, a visible light transmission (T _v ) of greater than 2.5%, preferably greater than 5% and even more preferably greater than 8%. - By "absorbent functional layer", also called here "absorbent" or

'Absorbent layer' means a layer which absorbs part of the sun's radiation and which consists essentially of a substance whose extinction coefficient spectral k (X) is greater than zero over the entire range of visible wavelengths (380-780 nm). The average extinction coefficient k of this material, for the visible range whose wavelength is from 380 nm to 780 nm, is at least 0.5, preferably greater than 1 and advantageously greater than 2.6. . The absorbent functional layer may be a metal or a nitride, for example, TiN, CrN or any other absorbing nitride, it may also be a carbide or a boride, provided that it meets the condition on the value of the extinction coefficient k .

- "Transparent dielectric coating" means a dielectric coating having an extinction coefficient k of not more than 0.2. The dielectric materials used are chosen from oxides, nitrides and oxynitrides of metals such as Zn, Sn, Si, Al, Zr, Ti and mixtures thereof. The term "dielectric material" also refers to layers doped with at least one other element, containing up to about 40% by weight of this other element, the latter having dielectric properties that do not differ in practice from the layers consisting of the said non-dielectric material. dope. For example, when the layer is made of nitride or silicon oxide, it may contain up to 10% by weight of aluminum (for example, layers deposited by sputtering process from a silicon target containing up to 10% by weight of aluminum). The dielectric coatings according to the invention may also consist of several individual layers comprising these same materials. The dielectric layers can be deposited by sputtering, they can also be deposited by the well-known technique called PECVD (Plasma-Enhanced Chemical Vapor Deposition).

- "Essentially metallic nature" means the characteristics generally accepted for defining a metal. This essentially metallic layer may, however, be slightly nitrided, oxidized or carbonated, without losing its basic metallic character provided that the atomic percentage of nitrogen or oxygen is less than 20%, preferably less than 15% and ideally less than 20%. 10%. Indeed, the atmosphere during the deposition of this metal layer may consist of pure noble gas, for example 100% of argon, or the atmosphere may, in addition to the noble gas, contain a little nitrogen or oxygen unintentionally coming from neighboring deposition areas.

- Generally also, the described layer systems are deposited on the face of the glass facing the interior of the building or the passenger compartment of the vehicle or, where appropriate, to the space between two glasses forming a multiple glazing so as to maximize protection against mechanical and chemical attack. In the case of a laminated glass for the automobile, the face of the glass carrying the layer system may be oriented towards the inside or towards the outside of the passenger compartment as the case may be. This means that when a layer-side property is mentioned, it is necessary to check on which face the multilayer system is deposited and therefore which side is impacted by the said property, that is to say the interior or the outside, knowing that when we talk about the interior, it is about the interior of the building or the cabin and conversely, when we talk about the outside, it is about the exterior of the building or cabin.

2. Solutions of the Prior Art Today, there is a demand for glazing with solar control whose light transmission is not greater than 14% and the reflection inside the building or the passenger compartment is less than 15%, while maintaining an acceptable aesthetic. To satisfy the first condition, that is to say having a relatively low light transmission, for the same material, the possibilities are either to increase the thickness of the absorbent layer, or to put several absorbent layers.

The patent application WO2002090281A2 describes a substrate carrying an absorbent functional layer surrounded by silicon nitride, characterized on the one hand by a weak light transmission and, on the other hand, by the fact that when the substrate is subjected to a heat treatment, the hue in reflection on the glass side varies little (AE * R _g <5). WO2002090281A2 explains, counterexamples to the support, that the coloring is more stable to the heat treatment if the absorbent layer is nitrided during the deposition. WO2006134335A1 shows the same tendency of color stabilization during a heat treatment, as soon as the metallic absorbent layer is nitrided in the case of layer systems allowing a significantly higher light transmission. According to WO2002090281A2, a nitrided absorbent has improved mechanical and chemical resistance. The rather low light transmission (<15%) can only be obtained by increasing the thickness of the absorbing layer. If WO2002090281A2 describes good coloration in reflection on the glass side and good stability of this color before and after heat treatment, the hue in reflection on the layer side corresponds to values of b * R _C ranging between 19.93 and 22.32 without heat treatment (a * R _C : -0.54-0.32), b * R _C values between 11.42 and 17.86 after heat treatment (a * R _C : -0.01-1.12) and very important differences

(greater than 15). This means that the layer-side coloration has a yellowish appearance and is not stable to heat treatment.

Still in the field of glazing with a low light transmission, patent application US20120177899A1 proposes a system with two less thick absorbent functional layers to improve the aesthetics. US20120177899A1 discloses the use of metal nitrides and all the examples presented have a light transmission of greater than 20%. No information is given on the color side film and without giving real values, US20120177899A1 mentions that its stack has good color stability after heat treatment. The application WO2014170613A1 aims to obtain a solar control glazing with a low light transmission, a very low internal reflection, a pleasant aesthetic and good resistance to heat treatments. Increasing the thickness of the absorbent would also increase the light reflection. The proposed solution is a coating which comprises two metallic absorbent layers separated by an intermediate layer of silicon nitride (SiN) whose thickness must be less than 45 nm. A first layer of nickel of 8 nm and a second of 7 nm makes it possible to obtain a light transmission of 32% and an interior reflection coloration characterized by a b * of -33 as long as the intermediate dielectric remains sufficiently thin. Therefore, no solution of the prior art gives the appropriate means to obtain a solar control layer system, stable to heat treatments and having both a low light transmission, a low level of internal reflection (Lm _n t < 15%), a pleasant external reflection (LR _OR t between 10 and 40%) and neutral shades in transmission and internal reflection. This is precisely the problem that the invention proposes to solve.

3. Objectives of the invention

The invention particularly aims to overcome the disadvantages of the prior art. More particularly, the invention aims to obtain a solar control glazing whose light transmission is between 5 and 20%, preferably between 8 and 14%, whose internal reflection is less than or equal to 15%, preferably less than 11% and whose external reflection is at least 10%, preferably between 15% and 25%, these values being based on the optical parameter "Y" as defined in the ELAB CI system. In order to satisfy the aesthetic criteria, the invention proposes a system of layers whose thickness adjustment makes it possible to obtain a glazing having an external reflection having specific colorimetric parameters for each shade that it is desired to obtain. As preferred examples, Table I provides the colorimetric parameters chosen to obtain a glazing which has an external reflection blue, green, bronze or gray. These colors are the classic colors frequently requested by architects.

Table I

In all cases, in addition to the colorimetric parameters for each color in external reflection, the color in transmission is characterized by a b * Ti_ less than or equal to 6 so as to maintain a neutral shade and in particular to avoid a yellowish appearance. The color in inner reflection is defined by a coefficient a * R _C between -5 and 6 and a coefficient D * R _c between -10 and 6.

More particularly, these specifications are given for glazings whose multilayer system is located on the interior side of the building. Otherwise, those skilled in the art will adapt the colorimetric parameters.

4. Presentation of the invention

The invention relates to a solar control glazing comprising on at least one of the faces of a glass substrate a layer system comprising at least two absorbent layers and nitride-based dielectric layers flanking each absorbent layer. The number of absorbing layers can be determined by the defined specifications and by the final aesthetics that one wants to obtain.

According to a first mode of the invention, the inventor has discovered that in a solar control system, to achieve the specifications as described above (paragraph 3), two criteria must be met. On the one hand, at least two absorbent functional layers are necessary, each of said functional layers being surrounded by dielectric coatings based on an oxide or a nitride and in contact with said dielectric coatings and on the other hand, it is necessary to at least one of said layers has an essentially metallic character.

According to a second mode of the invention and very surprisingly, the inventor has discovered that in a solar control system comprising at least two absorbent functional layers, each of said functional layers being surrounded by dielectric coatings based on an oxide or a nitride and in contact with said dielectric coatings, as soon as at least one of said layers has an essentially metallic character, the other absorbent may advantageously be a nitrided, carbonaceous or borated absorbent. In this case, the process used to obtain the targeted product is thereby simplified and more economical. because when a layer must remain essentially metallic, the equipment is much more demanding in terms of separation of the deposit chambers and will be all the more consequent.

In both embodiments, the presence of an essentially metallic absorbent therefore makes it possible to obtain the colorimetric properties specified in transmission and reflection both on the glass side and the layer side, as well as percentages in transmission and reflection (parameter Y defined in FIG. the CI ELAB system), within the limits set. Advantageously, the metal is chosen from Ni, Cr, W, Ti, Nb, Zr, Ta, Hf, V and an alloy of these metals. The inventor has also been able to demonstrate that when at least one of the absorbent functional layers is based on a boride, carbide or nitride of a metal chosen from Ni, Cr, W, Ti, Nb , Zr, Ta, Hf, V and an alloy of these metals, the entire system retains satisfactory optical characteristics described above. Preferably, for each absorbent functional layer, the metal is selected from Ni, Cr, Ti, W and Zr and an alloy of these metals. In particular, in the case of NiCrW, the alloy comprises at least 30% by weight of tungsten, preferably at 35% and advantageously at least 40%. The proportion of Ni is at least 9% by weight, preferably at least 25% and for example 30, 35 or 40% by weight.

It should be noted that, according to the two embodiments, the metal (or alloy) of the absorbent (s) nitrided (s), carbon (s) or boré (s) and the metal (or the alloy) of the absorbent (s) of essentially metallic nature, may be identical or different. To satisfy the invention, the thickness of an absorbent layer is between 0.2 nm and 50 nm, preferably this thickness is between 0.5 nm and 35 nm. More particularly, the thickness of the absorbent of essentially metallic nature is between 0.2 nm and 25 nm and the thickness of the absorbent in the form of a nitride, carbide or boride is between 0.5 nm and 50 nm.

Advantageously one or more of the dielectric coatings used in the invention is (are) based on metal nitrides whose metal is chosen from the group comprising silicon, aluminum, zirconium and titanium or a combination of these elements. The dielectric layers positioned on either side of the absorbent layers have the role of protecting them during a heat treatment by retaining their property of absorbent. To fulfill this role, each of these dielectric layers has a minimum of 8 nm in geometric thickness. More particularly, the thickness of the dielectric layers is between 8 nm and 200 nm. The person skilled in the art knows how to adjust the thicknesses according to the properties sought and already mentioned above. The relationship between the thicknesses of the dielectrics, as well as the ratio between the thicknesses of the absorbing layers, derive from the specifications that have been set (transmission, reflections, hues, etc.).

Surprisingly, the inventor has also discovered that the multilayer system of the invention also allows the shade to remain pleasant regardless of the angle at which the glazing is observed. Indeed, the hue of the reflection layer side remains pleasant because it is defined by a coefficient a * R _C between -5 and 8 and a coefficient b * R _C between -10 and 8 for an angle of vision between 8 , 5 ° and 75 °.

Finally, the stack as defined for each of the two embodiments can be heat treated without significant alteration of its optical properties.

More particularly, the glazing according to the invention comprises one of the following successions of layers:

Dielectric (Diel 1) / Absorbent (Abs 1) / Dielectric (Diel 2) / Absorbent (Abs 2) / Clear dielectric (Diel 3) dielectric coating Transparent dielectric coating (Diel 1) / absorbent (Abs 1) / Transparent dielectric coating (Diel 2) / absorbent (Abs 2) / Transparent dielectric coating (Diel 3) / absorbent (Abs 3) / Transparent dielectric coating (Diel 3) in which at least one absorbent is essentially metallic in nature according to a first embodiment of the invention and in which at least one absorbent is essentially metallic in nature and at least one absorbent comprises a metal boride, carbide or nitride, according to a second embodiment of the invention.

According to the invention, such a solar control glazing unit, even when it has a relatively low light transmission, can be adjusted so that it has optical characteristics having a reflection hue which is pleasant on the glass side and a neutral hue both in transmission in reflection from the layer side. The colorimetric parameters of the reflection color measured on the outer side (glass side) are adjusted according to the desired shade such as green, blue, gray or bronze, so as to satisfy the values given in Table I. In addition, the shade obtained remains pleasant depending on the angle of view, and is also stable to the heat treatment.

The hue of the reflection on the layer side remains pleasant because it is defined by a coefficient a * R _C between -5 and 8 and a coefficient b * R _C ranging between -10 and 8 for an angle of vision of between 8.5 ° and 75 °.

The materials constituting the layers are chosen so that the stack can undergo a heat treatment without the optical properties are significantly degraded, so that treated or not, the glazing has an appearance substantially unchanged. A heat treatment consists of heating at more than 600 ° C for several minutes. Traditionally, colorimetric variations are measured using the coordinates of the ELAB CI system. The colorimetric variation is expressed by the expression denoted ΔΕ *, expression corresponding to the formula:

or

represents the difference between the colorimetric coordinates L * of the glazing before and after heat treatment,

represents the difference between the colorimetric coordinates a * of the glazing before and after heat treatment,

represents the difference between the colorimetric coordinates b * of the glazing before and after heat treatment,

More particularly, and preferably, the glazing according to the invention has a colorimetric variation in reflection on the face side glass substrate,

less than 8, preferably less than 5, advantageously less than 3, and even preferably less than 2, when said glazing is subjected to a temperature of at least 630 ° C for a period of between 2 and 10 minutes.

In addition, the glazing according to the invention also preferably has a colorimetric variation in transmission,

less than 8, preferably less than 5, more preferably less than 3, when said glazing is subjected to a temperature of at least 630 ° C for a period of between 2 and 10 minutes.

The glazing according to the invention additionally has or not to the two preceding properties, a colorimetric variation in reflection side face stacking,

such as:

is lower 8, preferably less than 5, when said glazing is subjected to a temperature of at least 630 ° C for a period of between 2 and 10 minutes.

The glazing according to the invention can in addition to the layers described above comprise any additional layer necessary for an additional specific property with the exception of a functional layer based on silver. For example, the invention provides that an upper layer can be added for protection purposes of the layer system. Such a protective layer may be selected for example from oxides based on Ti and / or Zr.

Thus, the invention is based on a completely new and inventive approach in the sense that it is possible to produce a solar control glazing with very low light transmission simultaneously having satisfactory levels of reflection, a pleasant reflection tint on the glass side and a neutral shade in transmission and reflection on the layer side, regardless of the viewing angle, as well as good resistance to heat treatments.

The invention is illustrated by examples in the following paragraphs, it being understood that these examples should in no way be understood as a limitation of the invention.

5. Description of preferred embodiments of the invention

The choice of substrate does not limit the scope of the invention. In the same way, the examples of metals are not any more limiting of the principle of the invention which is based on the idea that it is possible to adjust the nature and the thicknesses of the layers constituting a solar control stack provided that that the stack comprises at least two absorbents and that at least one of these two absorbents is a metal. Advantageously and in a second mode, at least one of the absorbents is essentially metallic and at least one absorbent comprises a nitride, a carbide or a boride of a metal. The light absorbing functional layers are deposited by sputtering under reduced pressure, preferably assisted by a magnetic field (magnetron), under conditions customary for this type of technique and well known to those skilled in the art. The dielectric layers and more particularly the silicon nitride layers may also be produced by sputtering (magnetron) under conditions well known to those skilled in the art, from an aluminum doped silicon target, in an atmosphere consisting of a mixture of argon (30-70%) and nitrogen (30-70%) under a total pressure of less than 2 Pascal. Alternatively, the dielectric layers can be applied by the well-known technique called PECVD (Plasma Enhanced Chemical Vapor Deposition). In a PVD deposition technique, a succession of compartments each having its target or targets and its own atmosphere makes it possible to construct a multilayer coating. When the atmospheres are different between two successive compartments, it is then necessary to provide the installation with adequate means to ensure maximum physical separation between these atmospheres, which complicates the installation. It will be understood from then on all the advantage of being able, for example, to deposit a nitrided absorbent behind a dielectric which is itself a nitride.

According to a preferred embodiment, the dielectric layers enclosing the absorbent layer are based on silicon nitride, and advantageously substantially silicon nitride. The layer may contain another material up to 40% (weight), such as aluminum, titanium or zirconium. Conventionally, the silicon nitride can be obtained from a silicon target, optionally doped with aluminum or boron, by cathodic sputtering, using a magnetron, in a reactive atmosphere of nitrogen. and argon. The silicon target is doped to give it the electrical conduction necessary for sputtering, for example doped with at most 10% by weight of aluminum or boron, for example between 2% and 4%. The silicon nitride layers in the finished stack may be slightly oxidized over part of their thickness. The name S13N4 does not mean that the material is perfectly stoichiometric, it can be slightly under-nitrided or slightly oxidized. It is the same with other dielectrics. The dielectric layers have a minimum geometrical thickness of 8 nm. Whether it is an absorbent layer or a dielectric layer, one or the other or both may possibly be formed of several layers of different materials, for example to improve the chemical or thermal resistance. Other layers, such as a protective layer may be part of the stack.

Examples of glazing according to the invention as well as comparative examples (denoted R) are given in Tables I I to IX below. The optical properties are defined in simple glass, for glazing whose substrate is clear ordinary float glass and has a thickness of 6 mm. The layers are indicated in order, from top to bottom, starting from the glass. The geometrical thicknesses are expressed in nm.

For the various examples, the tables give the light transmission, the external and internal light reflection as well as the various useful colorimetric parameters. In the examples of the invention, when mentioning a property on the inside, it should be understood that this property is measured on the layer side. Unless otherwise stated, the light transmission T _v and the light reflection LR are measured with Illuminant D65, 2 ° (EN 410). The colorimetric coordinates L *, a *, b *, CI E, are also measured with Illuminant D65, 10 °. The angle at which the measurements are made is 8 ° for reflection and 0 ° for transmission.

In the examples, the SiN notations denote the silicon nitrides without representing a chemical formula, it being understood that the products obtained are not necessarily rigorously stoichiometric, but are those obtained under the deposition conditions indicated and which are close to the stoichiometric products. The SiN layers can contain up to about 10% by weight of aluminum from the target, they can also be slightly oxidized.

Table II illustrates the invention in the case where the stack comprises two absorbers. The thicknesses are given in nm for each layer. Comparative Examples R1 to R3 confirm that by using only one absorbent, it is not it is possible to satisfy all the specifications defined above, whether for a blue tint in reflection (RI and R2) or for a green tint (R3). The same conclusion applies when no metallic absorbent is present (R11 to R13) for bronze or gray tints. On the other hand, examples 4 to 10 clearly illustrate the invention, since as soon as we have two absorbers, at least one of which is metallic, the specifications referred to in paragraph 3 are well verified, in particular for green (ex 4-7), blue (ex 8) or gray (ex 9-10) in the examples cited.

Table II: 2 Absorbers (ABS)

Table III illustrates the invention by a series of examples in the case where the multilayer system comprises three layers of absorbent integrated in the following succession: glass / Diel 1 / Abs 1 / Diel 2 / Abs 2 / Diel 3 / Abs 3 / Diel 4. The thicknesses are given in nm for each layer. It can be seen that three absorbers make it possible to obtain a glazing having a light transmission of less than 15% and meeting the specifications defined in paragraph 3, since at least one absorbent is essentially metallic in nature, whether to obtain a hue blue (ex 18) or green (ex 19 to 22). On the other hand, the absence of metallic absorbent leads to the formation of products for which the specifications are not satisfied, and this, whatever the nature of the metal used in the nitride (ex R14 to R17). Table II I: 3 Absorbents (ABS)

The examples given in Table IV show that, according to the invention, a stack comprising at least two absorbers, one of which is essentially metallic in nature, it is possible to adjust the thicknesses (in nm) of to obtain a glazing whose characteristics correspond to the specifications that we have set (paragraph 3) and this, whatever the nature of the metal. Thus, it is possible to obtain a glazing with a blue tint in reflection on the layer side, while preserving the colorimetric parameters that one has set for the rest, that the absorbents are NiCrW or CrZr (ex 18 and 24 ). In the same way, the thicknesses can be adjusted to obtain a green hue in reflection on the layer side, by modifying not only the nature of the metallic absorbent but also by combining it with chromium nitride or titanium nitride (ex 19 -23 and 25).

Table IV: 3 absorbents

Another advantage of the invention is that the glazing retains its aesthetic qualities in reflection layer side irrespective of the viewing angle before and after heat treatment. This feature of the invention is illustrated by the examples in Tables V (before quenching) and VI (after quenching) for the different shades that have been proposed. For each shade, the stack is given at the top of the column with the thicknesses expressed in nm in parentheses. We can indeed see for these examples that for different angles of measurement,

is always between -5 and 8 and

is between -10 and 8.

Table V: Reflection on the layer side according to the angle of vision before quenching

Table VI: Reflection on the layer side according to the angle of vision after quenching

Just as the hue in reflection on the layer side varies little according to the angle of vision, as the examples in Tables V and VI show, the hue in reflection on the glass side is also quite stable (Tables VI I and VI II) for the different shades (blue, green, gray and bronze), before and after heat treatment. Here too, for each shade, the stack is given at the top of the column with the thicknesses expressed in nm in parentheses.

Table VI I: Reflection on the glass side according to the angle of vision before quenching.

Table VIII: Reflection on the glass side as a function of the viewing angle after quenching.

Finally, the stability of the colorimetric parameters when the glass carrying the stack of the invention is heat treated at temperatures above 600 ° C for several minutes, has been verified. Table IX shows that for all the tested examples which, in accordance with the invention, have at least two absorbents, at least one of which is essentially metallic in nature, the ΔΕ *, whether in transmission or in reflection (side layer and side glass) are always very weak and in all cases less than 3.5. Table IX

The glazing unit corresponding to the invention can be used as such as monolithic glazing, it can be incorporated in a multiple glazing, or in a laminated glazing unit. It can be used in building, automotive or home applications.

Claims

1. Solar control glazing comprising at least one glass substrate bearing on at least one of its faces a transparent multilayer stack, said transparent multilayer stack comprising at least two absorbent functional layers, each absorbent functional layer being surrounded by transparent dielectric coatings. characterized in that at least one of the absorbent functional layers is essentially metallic in nature and in that the light transmission is between 5 and 20%, preferably between 8 and 14%, the internal reflection is less than 15%, preferably less than 11% and the external reflection is greater than 10%, preferably between 15% and 25%, and the color in inner reflection is defined by a parameter a * R _C between -5 and 6 and by a parameter b * R _C between -10 and 6 and the color in transmission is characterized by a parameter b * n lower or equal to 6.

2. Glazing according to claim 1, characterized in that at least one of the at least two absorbent functional layers is essentially metallic in nature and at least one of the at least two absorbent functional layers comprises nitride, carbide or boride. a metal.

3. Glazing according to claim 2, characterized in that at least one of the at least two absorbent functional layers is essentially metallic in nature and at least one of the at least two absorbent functional layers comprises the nitride of a metal.

4. Glazing according to one of the preceding claims, characterized in that the transparent multilayer stack comprises three absorbent functional layers.

5. Glazing according to claim 4, characterized in that the three absorbent functional layers are essentially metallic in nature.

6. Glazing according to one of the preceding claims characterized in that the transparent multilayer stack comprises the following succession of layers from the substrate: transparent dielectric coating / absorbent functional layer / transparent dielectric coating / absorbent functional layer / transparent dielectric coating.

7. Glazing according to one of the preceding claims characterized in that the transparent multilayer stack comprises the following succession of layers from the substrate: transparent dielectric coating / absorbent functional layer / transparent dielectric coating / absorbent functional layer / transparent dielectric coating / absorbent functional layer / transparent dielectric coating.

8. Glazing according to one of the preceding claims, characterized in that one or more of the transparent dielectric coatings comprises the nitride of at least one metal selected from silicon, aluminum, zirconium, titanium or their mixture.

9. Glazing according to any one of the preceding claims, characterized in that the absorbent functional layer (s) (s) comprise at least one of the metals selected from i, Cr, W, Ti , Nb, Zr, Ta, Hf.

10. Glazing according to any one of the preceding claims, characterized in that the functional layer (s) (s) absorbent (s) of essentially metallic nature have a geometric thickness of between 0.2 e 25 nm, preferably between 1 and 12 nm.

11. Glazing according to claim 3, characterized in that each absorbent functional layer comprising the nitride of a metal selected from Ni, Cr, W, Ti, Nb, Zr, Ta, Hf, a. a geometric thickness of between 0.5 and 50 nm, preferably 5 to 30 nm.

Substrate according to any one of the preceding claims, characterized in that the layer-side reflection color as a function of the viewing angle is defined by a parameter a * R _C of between -5 and 10, preferably between 3 and 7 and a parameter D * R _c between -5 and 10, preferably between -3 and 8, for angles of view ranging from 8.5 ° to 75 °

Substrate according to any one of the preceding claims, including the colorimetric variation in transmission,

is less than 8, preferably less than 5, more preferably less than 3 and even more preferably less than 2 when said glazing is subjected to a temperature of at least 630 ° C for 2 to 10 minutes.

Substrate according to any one of the preceding claims, whose colorimetric variation in reflection on the glass side,

is less than 8, preferably less than 5, more preferably less than 3 when said glazing is subjected to a temperature of at least 630 ° C for 2 to 10 minutes.

15. Substrate according to any one of the preceding claims, in which the colorimetric variation in reflection on the layer side,

is less than 8, preferably less than 5, more preferably less than 4 when said glazing is subjected to a temperature of at least 630 ° C for 2 to 10 minutes.

Substrate according to any one of the preceding claims, wherein the colorimetric parameters in reflection on the glass side are such that: a * R _G is between -6 and 0 and b * R _G is less than or equal to -15, preferably a * R _G is between -5 and -1 and b * R _G is less than or equal to -16 so as to obtain a blue tint in external reflection or, a * R _G is less than or equal to -7 and b * R _G is between -5 and 5, preferably a * R _G is less than or equal to -8 and b * R _G is between -3 and 3 so as to obtain a green tint in external reflection or, a * R _g is between 1 and 6 and b * R _g is between 6 and 12, preferably a * R _g is between 2 and 4.5 and b * R _g is between 7 and 11 so as to obtain a tint bronze in external reflection or, a * R _g is between -3 and 3 and b * R _g is between -5 and 5, preferably a * R _g is between -2 and 0 and b * R _g is between -4 and 2, so as to obtain a gray tint in external reflection

17. Substrate according to any one of the preceding claims, characterized in that the transparent multilayer stack comprises at least one additional layer which is not silver, preferably said additional layer is a protective layer deposited above transparent multilayer stack and is selected from the Ti and / or Zr oxides, as well as their mixture.

18. Monolithic or multiple glazing incorporating the substrate according to any one of the preceding claims.

19. Laminated glazing incorporating the substrate according to any one of the preceding claims.