Laminated glazing including a silver-based functional coating

Abstract

The invention relates to a material comprising a transparent substrate coated with a functional coating comprising successively, starting from the substrate, an alternation of three silver-based functional metal layers called, starting from the substrate, first, second and third functional layers, and four dielectric coatings called, starting from the substrate, Di1, Di2, Di3 and Di4, each of which has an optical thickness Eo1, Eo2, Eo3 and Eo4, each dielectric coating comprising at least one dielectric layer, so that each functional metal layer is arranged between two dielectric coatings, characterized in that: - the ratio of the thickness of the second functional metal layer to the thickness of the first functional metal layer Ag2 / Ag1 is greater than or equal to 1.05,- the ratio of the thickness of the first functional metal layer to the thickness of the third functional metal layer Ag1 / Ag3 is greater than 1.05, - the ratio of the optical thicknesses Eo2 / Eo3 is greater than 1.00.,

Description

Title of the invention: Laminated glazing comprising a silver-based functional coating

[0001] The invention relates to a material comprising a transparent substrate coated with a functional coating capable of acting on solar radiation and / or infrared radiation. In the remainder of the description, the term "functional" qualifying a coating or a layer means "capable of acting on solar radiation and / or infrared radiation". The invention also relates to glazing comprising these materials as well as the use of such materials for manufacturing thermal insulation and / or solar protection glazing.

[0002] These glazings can be intended to equip vehicles or buildings, in particular with a view to preventing excessive overheating, so-called "solar control" glazings, caused by the ever-increasing importance of glazed surfaces in vehicle interiors and buildings.

[0003] The invention relates in particular to functional coatings comprising several silver-based functional metal layers. Traditionally, these complex functional coatings are adjusted to present a pleasing aesthetic appearance at reasonable viewing angles under dry conditions. This means that no color variation should be observed when viewing the material or glazing from the front or slightly from the side.

[0004] For some applications, curved or domed (non-flat) glazing is used, for example, in automotive applications such as roofs or windshields. In this case, the functional coatings must also be adjusted to remain consistent and not drastically change color (i.e., from blue to red) when the viewing angle gradually changes.

[0005] Functional coatings are known which make it possible to obtain, in a range of incidence angles from 0° (normal incidence) to 60° relative to the normal to the substrate, a bluish or neutral appearance in external reflection.

[0006] However, these functional coatings have been optimized in dry conditions, i.e. without taking into account the possible presence of water drops.

[0007] Indeed, in many applications, at least one face of these glazings is in contact with the external environment. This face is likely to become wet in the event of rain. However, when water drops are found on the external face of a material or glazing, the aesthetics can be drastically affected. Each water droplet is likely to refract and diffuse the incident light in a wide range of angles.

[0008] [Fig.l] schematically represents the successive interactions between an incident ray of light and a laminated glazing, in the absence or presence of a drop of water on the surface of the glazing. The laminated glazing comprises a material comprising a substrate coated with a functional coating laminated via a lamination interlayer to a second substrate.

[0009] In the absence of a water droplet, all incident rays refracted in the substrate propagate in it with angles relative to the normal less than 41°, corresponding to the critical air / glass angle.

[0010] In the presence of a water drop, due to their shape, almost all of the incident rays are transmitted into the water drop of index 1.33. A light ray is then likely to be refracted twice: once when it enters the drop (slightly due to the shape of the drop) and a second time when it leaves the drop. The water drop then acts like a prism. In this case, it becomes possible, depending on the configuration of the drop, to propagate in the substrate rays having angles relative to the normal up to 62°, corresponding to the critical water / glass angle. The presence of the water drop induces that rays are transmitted into the substrate with an angle relative to the normal of 42 to 62° whereas in the absence of a drop, the maximum propagation angle reached in the substrate would be 42°.

[0011] In the absence of a water droplet, the propagation angle in the material cannot exceed the critical angle, i.e. approximately 42° between the air and the glass, whereas in the presence of the droplet, the water / glass interface implies a larger critical angle, in particular approximately 62°. In addition, the shape of the water droplet has the effect of causing grazing rays to propagate in the droplet. Rays with a larger than expected angle of incidence, i.e. more grazing rays within the material, are likely to propagate in the outermost substrate.

[0012] The incident light striking the water droplet is therefore refracted and scattered over a wide range of angles in a very small area, these scattered rays are then incident at different angles on the substrate, then on the functional coating. These rays are then likely to be reflected at the different interfaces of the glazing.

[0013] In the presence of a water droplet, the rays therefore propagate in the substrate at angles that are not usually observed. However, functional coatings are complex and generate interference effects that are difficult to predict. This has a strong impact on aesthetics. Visually, the water drops present on the glazing appear in the form of colored drops. This appearance is undesirable, especially when these drops appear red.

[0014] The objective of the invention is therefore to propose a new material comprising a substrate coated with a functional coating which makes it possible to improve the aesthetics of a glazing in rainy weather by reducing, or even eliminating, this “colored drop” (GC) effect.

[0015] The effect obtained in reflection in the substrate at high angles of incidence accounts for the colors observed at the level of the water drops due to the diffraction of light by these water drops. To identify functional coatings likely to have a moderate or even weak colored drop appearance, the propagation of light rays with grazing angles in the water (approximately 75°) is simulated. These rays will refract in the glass with angles higher than the classic critical angles (up to 62°). The color of these reflections at the exit of the material is then determined.

[0016] The simulation takes into account the juxtaposition of different reflection phenomena occurring at the different interfaces: - water / substrate interface, - substrate / functional coating / lamination interlayer interface, - lamination interlayer / second substrate interface, - second substrate / air interface.

[0017] The reflection at the water / substrate interface is color neutral. It therefore has little impact on the colored drop effect. The reflection at the lamination interlayer / second substrate interface is very low or even negligible. Reflection at the second substrate / air interface is not necessarily negligible. However, it is often color-neutral and very attenuated, particularly in the case of automobile roofs comprising tinted substrates. The reflection at the interface between the substrate / functional coating / lamination interlayer has a very strong impact on the coloration. Due to the presence of the functional coating, all color combinations are possible.

[0018] In conclusion, the simulation takes into account all of its contributions. However, it appears that it is the presence of the functional coating that has the greatest impact on the color. To minimize the colored drop effect, the applicant was interested in developing a functional coating with few colorimetric variations in reflection and neutral or blue reflection colors over a high observation angle range.

[0019] In order to be able to identify the functional coatings likely to exhibit these properties, the applicant was interested in characterizing this “Colored Drop” effect (hereinafter GC). To this end, a specific optical model capable of accounting for the GC effect phenomenon was developed. This model makes it possible to evaluate by simulation the values ​​of a* and b* in external reflection characteristic of the GC effect hereinafter a*gc60 and b*gc60. These colors correspond to the colors due to the reflection of a light ray by a material coated with a drop of water with an angle of incidence of 75° in water. The GC effect physically corresponds to the determination of the colors measured in external reflection following a reflection in the substrate at an angle of 60°.

[0020] In order to validate the optical model, experiments were carried out using a prism. [Fig.2] shows the device used in the experiment. A prism with an index of 1.5 is placed on a material comprising a substrate coated with the functional coating. It is illuminated with a beam of white light. The colors in reflection are probed at different observation angles by changing the camera angle between 0 and 60°. The colors in external reflection due to the presence of the prism correspond to the colors obtained in external reflection due to the presence of water drops.

[0021] To compare the results obtained experimentally and by simulation, we choose: - in the case of the prism, to place the camera at an angle of 60° and - in the case of simulations, we choose a reflection angle in the material of 60°. A good correlation is obtained between the experimental results and the results obtained by simulation. This shows that the optical model is satisfactory.

[0022] It is considered that: - the GC effect is present for values ​​of a*gc60 > 12.5 and / or b*gc60 > 0, - the GC effect is moderate for a*gc60° < 12.5 and / or b*gc60° < 0, - the GC effect is weak for a*gc60° < 10.0 and b*gc60° < -5.

[0023] Thanks to this optical model, the applicant has highlighted a family of solutions meeting these criteria. Indeed, only particular combinations of thickness characteristics for the functional layers and the dielectric coatings make it possible to obtain a moderate, or even weak, GC effect.

[0024] The invention relates to a material or glazing having uniform and pleasant colors in reflection, preferably blue or neutral, whether the material is flat or curved, and this in dry or humid conditions.

[0025] The invention relates to a material comprising a transparent substrate coated with a functional coating comprising successively from the substrate an alternation of three silver-based functional metal layers called, starting from the substrate, first, second and third functional layers, and four dielectric coatings called, starting from the substrate, Di1, Di2, Di3 and Di4 which each have an optical thickness E11, E12, E13 and E14, each dielectric coating comprising at least one dielectric layer, so that each functional metal layer is arranged between two dielectric coatings, characterized in that: - the ratio of the thickness of the second functional metal layer to the thickness of the first functional metal layer Ag2 / Agl is greater than or equal to 1.05, preferably 1.07, or 1.10, - the ratio of the thickness of the first functional metal layer to the thickness of the third functional metal layer Agl / Ag3 is greater than 1.05, preferably 1.07, 1.10, - the ratio of optical thicknesses Eo2 / Eo3 is greater than 1.00, preferably greater than 1.05, 1.10, 1.15 or 1.20.

[0026] According to the invention, the second functional layer is thicker than the first and third functional layers, the first dielectric coating is the thinnest and the second dielectric coating is the thickest.

[0027] The material of the invention has a pleasant aesthetic appearance even when it includes water drops or when it is illuminated with high angles of incidence. The contrast between the color observed on a part of the material without water drops compared to a part of the material with water drops is less discordant.

[0028] The material remains aesthetically appealing in both dry and rainy environments.

[0029] The material of the invention advantageously exhibits colors in low-intensity reflection for a wide range of angles of incidence. The material of the invention advantageously exhibits in external reflection:

[0030] - a bluish or neutral color from all angles of observation, and / or - a stable color between 8° and 60° even in the presence of water drops, and / or - a limited RLext light reflection, in particular less than or equal to 20%.

[0031] The stability of the colors is characterized by the measurement of the variation of color between the two observation angles 8° and 60° of Aa*Rext = | a*Rext 60°-a*Rext 0° | and Ab*Rext = | a*Rext 60°-a*Rext 0° | . According to the invention, the colors are considered to be stable if Aa*Rext < 6 and Ab*Rext < 6.

[0032] The functional coating of the invention is particularly suitable for use in laminated glazing, to improve thermal comfort and the aesthetic appearance seen from the outside.

[0033] The invention therefore relates to a laminated glazing comprising a material according to the invention and at least one second substrate, the material and the second substrate being bonded together by means of a lamination interlayer.

[0034] Conventionally, the faces of a glazing unit are designated from the outside by numbering the faces of the substrates from the outside to the inside of the passenger compartment or the room it equips. This means that the incident sunlight passes through the faces in ascending order of their number. In the case of laminated glazing, all the faces of the substrates are numbered but the faces of the lamination interlayers are not numbered.

[0035] The laminated glazing according to the invention comprises a face 1 located outside the building or vehicle that it equips, faces 2 and 3 in contact with the lamination interlayer and a face 4 inside the building or vehicle. The silver-based functional coating is then positioned on face 2, that is to say on the internal face of the substrate located furthest to the outside.

[0036] The laminated glazing according to the invention may comprise curved substrates.

[0037] The laminated glazing may further comprise a functional coating comprising a conductive oxide layer positioned on face 4.

[0038] The invention also relates to: - laminated glazing according to the invention mounted on a vehicle or on a building, and - the use of laminated glazing according to the invention as glazing for buildings or vehicles, - a building, a vehicle comprising glazing according to the invention.

[0039] The preferred characteristics which appear in the remainder of the description are applicable both to the material according to the invention and, where appropriate, to the glazing, the method, the use, the building or the vehicle according to the invention.

[0040] All the luminous characteristics described are obtained according to the principles and methods of the ISO 9050, EN 410 and ISO 13837 standards relating to the determination of the luminous and solar characteristics of glazing used in glass for construction.

[0041] According to the invention: - light reflection corresponds to the reflection of solar radiation in the visible part of the spectrum, - light transmission corresponds to the transmission of solar radiation in the visible part of the spectrum, - light absorption corresponds to the absorption of solar radiation in the visible part of the spectrum.

[0042] The luminous and energy characteristics are measured according to illuminant A at 2°, perpendicular to the material mounted in laminated glazing with the functional coating positioned on face 3 (unless otherwise indicated): - TL corresponds to the light transmission in the visible range in %, - Rext corresponds to the external light reflection in the visible in %, observer side functional coating, - TE corresponds to the energy transmission, that is to say the percentage of the solar energy flow transmitted directly through the glass wall, - RE corresponds to energy reflection, that is to say the percentage of energy, from all solar radiation, reflected by the glass wall, - TTS corresponds to the total energy transmission, it is measured according to the convention A with a wind speed of 4 m / s.

[0043] The colorimetric characteristics are measured according to illuminant D65, observer at 10°, perpendicular to the material mounted in laminated glazing with the functional coating positioned on face 2 (unless otherwise indicated):

[0044] - a*Rext 8° and b* Rext 8° correspond to the colors in reflection a* and b* in the L*a*b* system observer functional coating side measured at an angle of 8°, - a*Rext 60° and b* Rext 60° correspond to the colors in reflection a* and b* in the L*a*b* system observer functional coating side measured at an angle of 60°, - a*gc60 and b*gc60 correspond to the colors in external reflection a* and b* in the L*a*b* system following a 60° reflection in the material.

[0045] The material has excellent energy and thermal properties. This translates into: - energy reflection values ​​RE greater than 44% and / or - energy transmission values ​​lower than 38% and / or - total energy transmission values ​​of less than 44%, measured on a laminated glazing comprising the functional coating on face 2 deposited on a clear glass substrate and laminated to a second clear glass substrate via a clear PVB polymer interlayer.

[0046] These properties are measured on ordinary clear glass. An ordinary clear glass 4 to 6 mm thick has the following luminous characteristics: - a light transmission between 87 and 91.5%, - a light reflection between 7 and 9.5%, - a light absorption between 0.3 and 5%.

[0047] A so-called clear PVB lamination interlayer has a light transmission greater than 80%.

[0048] Conventionally, refractive indices are measured at a wavelength of 550 nm.

[0049] Unless otherwise stated, the thicknesses mentioned in this document without further details are physical, real or geometric thicknesses called Ep and are expressed in nanometers (and not optical thicknesses). The optical thickness Eo is defined as the physical thickness of the layer considered multiplied by its refractive index at the wavelength of 550 nm: Eo = n*Ep. Since the refractive index is a dimensionless value, it can be considered that the unit of the optical thickness is that chosen for the physical thickness.

[0050] According to the invention, a dielectric coating corresponds to a sequence of layers comprising at least one dielectric layer, located between the substrate and the first functional layer (Di1), between two functional layers (Di2 or Di3) or above the last functional layer (Di4).

[0051] If a dielectric coating is composed of several dielectric layers, the optical thickness of the dielectric coating corresponds to the sum of the optical thicknesses of the different dielectric layers constituting the dielectric coating.

[0052] If a dielectric coating comprises an absorbent layer for which the refractive index at 550 nm comprises an imaginary part of the non-zero (or non-negligible) dielectric function, for example a metallic layer, the thickness of this layer is not taken into account for the calculation of the optical thickness of the dielectric coating.

[0053] The thickness of the blocking layers is not taken into account for the calculation of the optical thickness of the dielectric coating.

[0054] For the purposes of the present invention, the terms “first”, “second”, “third” and “fourth” for the functional layers or dielectric coatings are defined starting from the substrate carrying the stack and referring to the layers or coatings of the same function. For example, the functional layer closest to the substrate is the first functional layer, the next one away from the substrate is the second functional layer, etc.

[0055] The functional coating is deposited by magnetic field-assisted sputtering (magnetron process). According to this advantageous embodiment, all the layers of the coatings are deposited by magnetic field-assisted sputtering. Unless otherwise specifically stated, the expressions "above" and "below" do not necessarily mean that two layers and / or coatings are arranged in contact with each other. When it is specified that a layer is deposited "in contact" with another layer or coating, this means that there cannot be one (or more) layer(s) intercalated between these two layers (or layer and coating).

[0056] In the present description, unless otherwise indicated, the expression "based on", used to qualify a material or a layer as to what it contains, means that the mass fraction of the constituent that it comprises is at least 50%, in particular at least 70%, preferably at least 90%.

[0057] The functional coating comprises at least three silver-based metallic functional layers (Fl, F2 and F3), each disposed between two dielectric coatings (Di1, Di2, Di3, Di4).

[0058] The silver-based metal functional layers comprise at least 95.0%, preferably at least 96.5% and more preferably at least 98.0% by mass of silver relative to the mass of the functional layer. Preferably, a silver-based metal functional layer comprises less than 1.0% by mass of metals other than silver relative to the mass of the silver-based metal functional layer.

[0059] The three functional metal layers can satisfy the following characteristics: - at least the ratio of the thickness of the second functional metal layer to the thickness of the first functional metal layer Ag2 / Agl or the ratio of the thickness of the first functional metal layer to the thickness of the third functional metal layer Agl / Ag3 is greater than 1.10, and / or - the first silver-based functional metal layer has a thickness of between 10 and 15 nm, and / or - the second silver-based functional metal layer has a thickness of between 12 and 17 nm, and / or - the third silver-based functional metal layer has a thickness of between 10 and 15 nm, and / or - the first silver-based functional metal layer has a thickness of between 11 and 14 nm or between 11 and 13 nm, and / or or between 11.5 and 13 nm, and / or - the second silver-based functional metal layer has a thickness of between 12.5 and 16 nm excluding the limit, between 13 and 14 nm, and / or - the third silver-based functional metal layer has a thickness of between 10.5 and 13 nm, preferably between 10.5 and 12 nm.

[0060] The stack may further comprise at least one blocking layer located in contact with a functional metal layer.

[0061] The blocking layers traditionally have the function of protecting the functional layers from possible degradation during the deposition of the upper anti-reflective coating and during a possible high-temperature heat treatment, such as annealing, bending and / or quenching.

[0062] The blocking layers are chosen from: - metallic layers based on a metal or a metallic alloy, metallic nitride layers, and metallic oxynitride layers of one or more elements chosen from titanium, zinc, tin, nickel, chromium and niobium, - metal oxide layers of one or more elements chosen from titanium, nickel, chromium and niobium.

[0063] The blocking layers may in particular be layers of Ti, TiN, TiOx, Nb, NbN, Ni, NiN, Cr, CrN, NiCr, NiCrN, SnZnN. When these blocking layers are deposited in metallic, nitrided or oxynitrided form, these layers may undergo partial or total oxidation depending on their thickness and the nature of the layers surrounding them, for example, at the time of deposition of the following layer or by oxidation in contact with the underlying layer.

[0064] According to advantageous embodiments of the invention, the blocking layer(s) satisfy one or more of the following conditions: - each silver-based functional metal layer may be located below and / or above, and optionally in contact with, a contact blocking layer chosen from a blocking sub-layer and a blocking over-layer, and / or - the blocking layer may be based on at least one element chosen from nickel, chromium, niobium, tantalum and titanium, and / or - each functional metal layer is in contact with a blocking overlayer, and / or - the thickness of each blocking layer is at least 0.1 nm, preferably between 0.2 and 2.0 nm or between 0.2 and 0.5 nm.

[0065] According to the invention, the blocking layers are considered as not being part of a dielectric coating. This means that their thickness is not taken into account in the calculation of the optical or geometric thickness of the dielectric coating located in contact with them.

[0066] By "dielectric layer" within the meaning of the present invention, it is to be understood that from the point of view of its nature, the material is "non-metallic", that is to say is not a metal. In the context of the invention, this term designates a material having an n / k ratio over the entire visible wavelength range (from 380 nm to 780 nm) equal to or greater than 5.

[0067] The dielectric layers of the coatings have the following characteristics alone or in combination: - they are deposited by magnetic field-assisted cathode sputtering, and / or - they are chosen from the oxides or nitrides of one or more elements chosen from titanium, silicon, aluminum, zirconium, tin and zinc, and / or - they are chosen from: oxide layers of one or more elements chosen from titanium, silicon, aluminum, zirconium, iron, chromium, cobalt, manganese, tungsten, niobium, bismuth, tantalum, zinc and / or tin, nitride layers of one or more elements chosen from silicon, zirconium and aluminum, oxynitride layers of one or more elements chosen from silicon, zirconium and aluminum, layers of metal sulfide such as zinc sulfide, and / or - they have a thickness greater than 2 nm, preferably between 4 and 100 nm.

[0068] According to advantageous embodiments of the invention, the dielectric coatings of the functional coatings satisfy one or more of the following conditions: - the dielectric layers may be based on oxide or nitride of one or more elements chosen from silicon, zirconium, titanium, aluminum, tin, zinc, and / or - at least one dielectric coating comprises at least one dielectric layer with a barrier function, and / or - each dielectric coating comprises at least one dielectric layer with a barrier function, and / or - the dielectric layers with barrier function are based on silicon and / or aluminum compounds chosen from oxides such as SiO2 and A12O3, nitrides Si3N4 and AIN and oxynitrides SiOxNy and A10xNy, based on zinc and tin oxide or based on titanium oxide, - the dielectric layers with barrier function are based on silicon and / or aluminum compounds and optionally include at least one other element, such as aluminum, hafnium and zirconium, and / or - at least one dielectric coating comprises at least one dielectric layer with a stabilizing function, and / or - each dielectric coating comprises at least one dielectric layer with a stabilizing function, and / or - the dielectric layers with a stabilizing function are preferably based on an oxide chosen from zinc oxide, tin oxide, zirconium oxide or a mixture of at least two of them, and / or - the dielectric layers with a stabilizing function are preferably based on crystallized oxide, in particular based on zinc oxide, possibly doped with at least one other element, such as aluminum, and / or - each functional layer is above a dielectric coating, the upper layer of which is a dielectric layer with a stabilizing function, preferably based on zinc oxide and / or below a dielectric coating, the lower layer of which is a dielectric layer with a stabilizing function, preferably based on zinc oxide.

[0069] Preferably, each dielectric coating consists solely of one or more dielectric layers. Preferably, there is therefore no absorbent layer in the dielectric coatings so as not to reduce the light transmission.

[0070] The dielectric layers may have a barrier function. Dielectric layers with a barrier function (hereinafter barrier layer) are understood to mean a layer made of a material capable of acting as a barrier to the diffusion of oxygen and water at high temperature, coming from the ambient atmosphere or from the transparent substrate, towards the functional layer. Such dielectric layers are chosen from the layers: - based on silicon and / or aluminum compounds chosen from oxides such as SiO2 and Al2O3, nitrides such as nitrides such as Si3N4 and AlN, and oxynitrides such as SiOxNy> AlOxNy optionally doped with at least one other element, - based on zinc and tin oxide, - based on titanium oxide.

[0071] Preferably, each coating comprises at least one dielectric layer consisting of: - of an aluminum and / or silicon nitride or oxynitride or - a mixed oxide of zinc and tin, or - of a titanium oxide.

[0072] These dielectric layers have a thickness: - less than or equal to 80 nm, less than or equal to 60 nm or less than or equal to 25 nm, and / or - greater than or equal to 5 nm, greater than or equal to 10 nm or greater than or equal to 15 nm.

[0073] The functional coatings of the invention may comprise dielectric layers with a stabilizing function. For the purposes of the invention, “stabilizing” means that the nature of the layer is selected so as to stabilize the interface between the functional layer and this layer. This stabilization leads to strengthening the adhesion of the functional layer to the layers surrounding it, and in fact it will oppose the migration of its constituent material.

[0074] The dielectric layer(s) with stabilizing function may be directly in contact with a functional layer or separated by a blocking layer.

[0075] Preferably, the last dielectric layer of each dielectric coating located below a functional layer is a dielectric layer with a stabilizing function. Indeed, it is advantageous to have a layer with a stabilizing function, for example, based on zinc oxide below a functional layer, because it facilitates the adhesion and crystallization of the silver-based functional layer and increases its quality and stability at high temperature.

[0076] It is also advantageous to have a stabilizing functional layer, for example, based on zinc oxide above a functional layer, to increase its adhesion and optimally oppose diffusion on the side of the stack opposite the substrate.

[0077] The dielectric layer(s) with stabilizing function may therefore be located above and / or below at least one functional layer or each functional layer, either directly in contact with it or separated by a blocking layer.

[0078] Advantageously, each dielectric layer with barrier function is separated from a functional layer by at least one dielectric layer with stabilizing function.

[0079] The zinc oxide layer may optionally be doped with at least one other element, such as aluminum. The zinc oxide is crystallized. The zinc oxide-based layer comprises, in order of increasing preference, at least 90.0%, at least 92%, at least 95%, at least 98.0% by mass of zinc relative to the mass of elements other than oxygen in the zinc oxide-based layer.

[0080] Preferably, the dielectric coatings of the functional coatings comprise a zinc oxide-based dielectric layer located below the silver-based metal layer.

[0081] The zinc oxide layers have, in order of increasing preference, a thickness: - of at least 3.0 nm, of at least 4.0 nm, of at least 5.0 nm, and / or - of at most 25 nm, of at most 10 nm, of at most 8.0 nm.

[0082] According to advantageous embodiments of the invention, the dielectric coatings satisfy one or more of the following conditions: - the dielectric coating Dil has an optical thickness Eol between 50 and 80 nm, - the dielectric coating Di2 has an optical thickness Eo2 between 160 and 180 nm, - the dielectric coating Di3 has an optical thickness Eo3 between 110 and 150 nm, - the dielectric coating Di4 has an optical thickness Eo4 between 70 and 90 nm, - the ratio of optical thicknesses Eol / Eo2 is less than 0.40, - the ratio of optical thicknesses Eol / Eo3 is less than 0.40, - the ratio of optical thicknesses Eol / Eo2 is less than 0.60, - the ratio of optical thicknesses Eol / Eo4 is less than 1.00, - each dielectric coating comprises a layer comprising silicon chosen from layers based on silicon nitride, - the sum of the physical thicknesses of all layers comprising silicon in each dielectric coating is greater than 25% of the total thickness of the dielectric coating, - each dielectric coating located below a functional layer comprises a zinc oxide-based layer located below, in contact with or separated by a blocking layer, the functional layer, - each dielectric coating located above a functional layer comprises a zinc oxide-based layer located above, in contact with or separated by a blocking layer, from the functional layer, - each dielectric coating located below a functional layer comprises a zinc and tin oxide-based layer located below and in contact of a zinc oxide-based layer.

[0083] The functional coating may optionally comprise a protective top layer. The protective top layer is preferably the last layer of the stack, i.e. the layer furthest from the coated substrate of the stack. These protective top layers are considered to be included in the last dielectric coating. These layers generally have a thickness of between 2 and 10 nm, preferably 2 and 5 nm.

[0084] The protective layer may be chosen from a layer of titanium, zirconium, hafnium, zinc and / or tin, this or these metals being in metallic, oxidized or nitrided form. Advantageously, the protective layer is a layer of titanium oxide, a layer of zinc and tin oxide or a layer based on titanium and zirconium oxide.

[0085] Another particularly advantageous embodiment relates to a substrate coated with a stack defined starting from the transparent substrate comprising: - a first dielectric coating comprising at least one layer with a barrier function and one dielectric layer with a stabilizing function, - possibly a blocking layer, - a first functional layer, - possibly a blocking layer, - a second dielectric coating comprising at least one dielectric layer with a lower stabilizing function, a layer with a barrier function and a dielectric layer with an upper stabilizing function, - possibly a blocking layer, - a second functional layer, - possibly a blocking layer, - a third dielectric coating comprising at least one dielectric layer with a lower stabilizing function, a layer with a barrier function, a dielectric layer with an upper stabilizing function, - possibly a blocking layer, - a third functional layer, - possibly a blocking layer, - a fourth dielectric coating comprising at least one dielectric layer with a stabilizing function, one layer with a barrier function, - possibly a protective layer.

[0086] Another particularly advantageous embodiment comprises a stack which comprises, starting from the substrate: - a first dielectric coating comprising at least one layer based on silicon nitride and one layer based on zinc oxide, - possibly a blocking layer, - a first functional layer, - possibly a blocking layer, - a second dielectric coating comprising at least three successive layers, a zinc oxide-based layer, a silicon nitride-based layer and a zinc oxide-based layer, - possibly a blocking layer, - a second functional layer, - possibly a blocking layer, - a third dielectric coating comprising at least three successive layers, a zinc oxide-based layer, a silicon nitride-based layer and a zinc oxide-based layer, - possibly a blocking layer, - a third functional layer, - possibly a blocking layer, - a fourth dielectric coating comprising at least one zinc oxide-based layer, one silicon nitride-based layer and - possibly a protective layer.

[0087] In configurations in the form of laminated glazing, the colorimetric properties are calculated with: - materials comprising a substrate coated with a functional coating mounted in laminated glazing, - the laminated glazing comprises a material comprising a 2 mm ordinary soda-lime glass substrate and another 2 mm soda-lime glass substrate, the two substrates are separated by a 0.76 mm Polyvinyl Butyral (PVB) lamination interlayer, - the silver-based functional coating is positioned on face 2, - if present, the functional coating based on conductive oxide is preferably positioned on face 4.

[0088] The substrates may be mineral glass or transparent polymer material substrates. The substrates are preferably mineral glass.

[0089] The mineral glass substrates which constitute the glazing can be made of soda-lime, aluminosilicate or borosilicate glass.

[0090] The substrates may be made of transparent polymeric material which include poly(methyl methacrylate) (PMMA), polycarbonate (PC), polyurethane or polyurea (PU) substrates.

[0091] The substrate is preferably transparent, colorless (in which case it is clear or extra-clear glass) or colored, for example blue, gray or bronze.

[0092] The substrate may be an ultra-thin glass, for example with a thickness of less than 0.7 mm.

[0093] The substrate may be a (thermally) tempered glass.

[0094] The silver-based functional coating may advantageously be deposited on a clear glass substrate to allow maximum reflection of infrared radiation and thus obtain a low total energy transmission.

[0095] The silver-based functional coating can be deposited on a tinted substrate in order to neutralize the external reflection appearance. However, in this case a compromise must be found between color neutralization and energy performance.

[0096] Preferably, the lamination interlayers comprise one or more sheets of organic polymers.The organic polymers are chosen from polyvinyl butyral (PVB), polyurethanes (PU), polyureas, ethylene vinyl acetate (EVA), polyolefins (including polyethylene (PE), polypropylene (PP) or polyisobutylene (P-IB)), polyvinyl chloride and its derivatives (for example poly(vinyl dichloride) (PVDC)), styrenic polymers (for example polystyrene (PS), acrylostyrene butadiene (ABS), styrene acrylonitrile (SAN)), polyacrylics (including polyacrylonitrile (PAN) and poly(methyl methacrylate) (PMMA)), polyesters (including poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT)), polyoxymethylene (POM), polyamides (PA), fluorinated polymers such as polychlorotrifluoroethylene (PCTFE), polycarbonates (PC), aromatic polysulfones including polysulfone (PSU), polyphenylene ether (PPE), epoxy (EP) alone or in a mixture and / or copolymer of several of them. The lamination interlayer can be tinted.

[0097] Conventionally, the interlayers have a thickness between 0.20 and 3.00 mm. An interlayer can be composed of one or more polymer sheets. The thickness range given is the total thickness of the interlayer.

[0098] The material, i.e. the substrate coated with the functional coating, may undergo a high temperature heat treatment such as annealing, for example by flash annealing such as laser or flame annealing, quenching and / or bending. The temperature of the heat treatment is greater than 400°C, preferably greater than 450°C, and better still greater than 500°C. The substrate coated with the functional coating may therefore be curved and / or quenched.

[0099] The material of the invention is particularly suitable for use in laminated glazing for automobiles, in particular curved glazing such as roofs or windshields. The laminated glazing according to the invention is therefore preferably automotive glazing such as automotive roof glazing or a windshield.

[0100] The laminated glazing may also have a light transmission greater than 60%, greater than 70%, or greater than 80%. The laminated glazing according to the invention, when used in particular as a windshield or side glazing, preferably has a light transmission TL of preferably at least 70% and even at least 75%. or even at least 80%.

[0101] The laminated glazing may have a light transmission of less than 50%, less than 30%, less than 20% or less than 10%. The laminated glazing according to the invention, when used in particular as a glazed roof, preferably has a light transmission TL of at most 10% and even 1 to 6%.

[0102] For an automobile roof, at least one or all of the following criteria are preferred: - an energy transmission TE of at most 10% and even 4 to 6%,

[0103] - an energy reflection RE (preferably on the face side Fl) of at most 10%, better still 4 to 5%, - and a total transmission of solar energy TTS <30% and even <26%, even from 20 to 23%.

[0104] Laminated glazing can be used as a windshield to provide a combination of solar control and heating functions with advantageous reflective optical properties.

[0105] Finally, the glazing of the invention is suitable in building applications, in particular when the glazing is used as a separation element with the exterior. The glazing is then indifferently in the form of single glazing, multiple glazing or laminated glazing. Multiple glazing comprises a material according to the invention and a second substrate separated by a gas layer.

[0106] In an advantageous embodiment, the functional coating may be used in combination with another functional coating such as a low-emissivity coating in a laminated glazing. According to this advantageous embodiment, the laminated glazing further comprises another functional coating. This other functional coating is preferably positioned on face 4. This functional coating may comprise a conductive oxide layer (TCO).

[0107] This functional coating based on a conductive oxide layer advantageously has the following characteristic(s): - the functional layer is chosen from fluorine-doped tin oxide, antimony-doped tin oxide and / or indium tin oxide, - the functional layer has a geometric thickness between 70 and 200 nm, between 75 and 150 nm, between 80 and 130 or between 90 and 110 nm, - the conductive oxide layer is preferably arranged between two dielectric coatings comprising at least one dielectric layer, - the dielectric coatings comprise dielectric layers chosen from layers based on silicon oxide, layers based on nitride of one or more elements chosen from silicon, aluminum or zirconium, preferably based on silicon nitride, layers based on zinc and tin oxide, layers based on zinc oxide or layers based on titanium oxide.

[0108] Preferably, the conductive oxide-based coating is deposited on tinted glass.

[0109] This configuration comprising at least two functional coatings makes it possible to improve energy performance and in particular to lower the total solar energy transmission factor (TTS) below 14% with an external light reflection of less than 20% and colors in external reflection which are blue or neutral for any observation angle.

[0110] The invention also relates to a method for obtaining a material which does not exhibit color variations when covered with water drops. The material comprises a transparent substrate coated with a functional coating. Preferably, the functional coating comprises successively from the substrate an alternation of three silver-based functional metal layers called, starting from the substrate, first, second and third functional layers, and four dielectric coatings called, starting from the substrate, Di1, Di2, Di3 and Di4 which each have an optical thickness E11, E12, E13 and E14, each dielectric coating comprising at least one dielectric layer, so that each functional metal layer is arranged between two dielectric coatings.

[0111] The method comprises: a) a step during which a functional coating is selected, b) a step during which the parameters a*gc60 and b*gc60 in external reflection characteristic of the colored drop effect are determined, corresponding to the colors in external reflection following a reflection in the substrate with an angle of 60° cl) if the parameters a*gc60 and b*gc60 do not satisfy a*gc60<10 and b*gc60<0, the functional coating is modified, c2) if the parameters a*gc60 and b*gc60 satisfy a*gc60<10 and b*gc60<0, the functional coating is deposited on the substrate.

[0112] The details and advantageous characteristics of the invention emerge from the following non-limiting examples. Examples I. Nature of layers and coatings

[0113] Functional coatings defined below are deposited on clear soda-lime glass substrates with a thickness of 2.1 mm. The functional metal layers (F) are silver (Ag) layers. The blocking layers are nickel-chromium alloy (NiCr) metal layers. The dielectric coatings of the functional coatings include barrier layers and stabilizing layers. The barrier layers are silicon nitride-based, aluminum-doped (Si3N4:Al), silicon nitride-based, and zirconium doped with aluminum (SiZrl7Nx) or based on mixed zinc and tin oxide (SnZnOx). The stabilizing layers are made of zinc oxide (ZnO).

[0114] The conditions for deposition of the layers, which were deposited by sputtering (so-called “magnetron cathode” sputtering), are summarized in Table 1.

[0115] [Tables 1] Tab. 1 Target used Deposition pressure Gas Si3N4 Si:Al at 92:8 wt.% 3.2.10-3 mbar Ar / (Ar + N2) at 55% SiZr(17)Nx Si:Zr:Al at 78:17:5 at.% 2.10-3 mbar Ar / (Ar + N2) at 45% ZnO Zn:Al at 98:2% by weight 1.8.10-3 mbar Ar / (Ar + 02) at 63% SnZnOx Sn:Zn (60:40% by weight) 1.5* 103 mbar Ar / (Ar + 02) at 39% NiCr Ni (80% at.): Cr (20% at.) 2-3.103 mbar Ar at 100% Ag Ag 3.10-3 mbar Ar at 100%

[0116] At. = atomic.

[0117] Table 2 lists the materials and physical thicknesses in nanometers (unless otherwise indicated) of each layer or coating that constitutes the coatings according to their position relative to the substrate carrying the stack (last line at the bottom of the table).

[0118] [T ableaux2] Material RFI RF2 RF3 RF4 RFX Di4 Si3N4 27.1 29.1 28.5 22.7 5-30 ZnO 14 14 14 14 14 CB NiCr 0.1 0.1 0.1 0.1 0.1 CF3 Ag 10.8 10.7 10.8 10.8 10-14 Di3 ZnO 14 14 14 14 14 ZnSnOx 8 8 8 8 8 SiZr(17)NX 12.3 17.3 17.5 10.5 5-30 Si3N4 20.9 14 13.6 20.4 5-30 ZnO 14 14 14 14 14 CB NiCr 0.1 0.1 0.1 0.1 0.1 CF2 Ag 13.6 13.4 13.6 13.3 12-15 Di2 ZnO 15 15 15 15 15 ZnSnOx 11.5 8 8 8 8 SiZr(17)NX 11.1 14.8 16.1 12.4 5-30 Si3N4 20 13.8 14.8 12.9 5-30 SiZr(17)NX 13.1 13.2 11.4 16.1 5-30 ZnO 15 15 15 15 15 CB NiCr 0.1 0.1 0.1 0.1 0.1 CFI Ag 12.3 12.5 12.3 11.8 12-14 Dil ZnO 12 12 12 12 12 ZnSnOx 9 8 8 8 8 SiZr(17)NX 10.3 11.3 11.4 10.3 5-30 Glass substrate

[0119] Di: Dielectric coating; CB: Blocking layer; CF: Functional layer.

[0120] Table 3 shows the optical thicknesses and thickness ratios of the functional layers and dielectric coatings. In this table, RFX corresponds to the thickness ranges explored by simulation.

[0121] [Tables3] Material Ml M2 M3 M4 Eo Dil 66.1 66.4 66.6 64.1 Eo Di2 179.2 168.4 169.3 167.8 Eo Di3 142.5 140.2 139.9 137.4 Eo Di4 82.2 86.2 85.0 73.4 Ag2 / Agl 1.11 1.07 1.11 1.13 Ag2 / Ag3 1.26 1.25 1.26 1.23 Agl / Ag3 1.14 1.17 1.14 1.09 Eo Di2 / Dil 2.71 2.54 2.54 2.62 Eo Di2 / Di3 1.26 1.20 1.21 1.22 Eo Di2 / Di4 2.18 1.95 1.99 2.29

[0122] The substrates undergo a high temperature heat treatment, i.e. a treatment lasting several minutes at a temperature above 550°C. II. Laminated glazing configuration

[0123] Materials comprising a transparent substrate, one of the faces of which is coated with a functional coating, have been assembled in the form of laminated glazing. Laminated glazing, hereinafter referred to as the “Lam.” configuration, has a structure of the type first substrate 2.1 mm / lamination interlayer / second substrate 2.1 mm. The silver-based functional coating is positioned on face 2. A low-emissivity coating with a normal emissivity of 33% is positioned on face 4. An example of a functional low-emissivity coating can comprise the following sequence of layers: Glass / / Si3N4 30 nm / SiO2 17 nm / InO2:Sn 72 nm / Si3N4 9 nm / SiO2 50 nm. The interlayer chosen is a tinted PVB or a transparent PVB. The second substrate is chosen from clear glass or tinted glass such as Saint Gobain Parsol Ultra Grey Venus (VG 10) glass with a TL of 10%. Table 4 lists the different laminated configurations tested.

[0124] [Tables4] Glazing Lam.lD Lam.lC Lam.2D Lam.2C Lam.3D Lam.3C Lam.4D Lam.4C 1st sub. Ml Ml M2 M2 M3 M3 M2 M2 Int. Light Tinted Light Tinted Light Tinted Light Tinted 2nd Sub. VG10 Clear VG10 Clear VG10 Clear VG10 Clear III. Exploratory research

[0125] Extensive explorations have been carried out by optical simulation to determine the functional coatings likely to confer the desired optical and thermal properties. In these simulations, all layer thicknesses were varied except for those of the zinc oxide layers, the zinc oxide layers, and the tin oxide layers. The thickness ranges in which the layers varied are defined in Table 2 under RFX. The results were obtained using the optical model developed to determine the “colored drop” effect.

[0126] The results of these Brownian explorations are represented by figures 3, 4 and 5.

[0127] Figures 3, 4 and 5 represent the distribution of functional coatings having the following properties:

[0128] - the “stars” correspond to functional coatings presenting a TL > 68% and a TTS < 38%, and an unacceptable GC effect, - the “circles” correspond to functional coatings presenting a moderate GC effect (<12.5; 0), - the "crosses" correspond to functional coatings with a low GC effect (<10; -5).

[0129] [Fig.3] represents the distribution of functional coatings with the combination of these properties: TL > 68%, TTS < 38%, values ​​of a*Rext and b*Rext < 0 and values ​​of a*60Rext and b*60Rext < 0, as a function of the thickness of the following elements of the functional coatings: - thicknesses of the functional layers Agi, Ag2 and Ag3, - thicknesses of all the nitride layers present in a dielectric coating Dil, Di2, Di3, Di4, called respectively NDil, NDi2, NDi3, NDi4. For example, NDi2 includes the sum of the thicknesses of the Si3N4 and SiZrN layers in the dielectric coating Di2. In this figure, considering the density of the results, the set of "stars" corresponds to the light gray surface, the set of "circles" corresponds to the dark gray surface and the set of "crosses" corresponds to the black surface. This [Fig.3] clearly highlights that the moderate or weak GC effect can only be obtained for a restricted range of thickness for each element considered. The most advantageous combination of properties is obtained with Ag3 <Agl, Ag3<Ag2, Ag2> Agl and Eo2>Eo3.

[0130] [Fig.4] and 5 represent the distribution of functional coatings exhibiting unacceptable, moderate and low BP effect respectively: - depending on the thickness of the Agi and the thickness of the Ag2, - depending on the thickness of the Agi and the thickness of the Ag3.

[0131] [Fig.4] clearly shows that the moderate or absent colored drop effect is obtained when: - the second functional layer has a thickness greater than the first functional layer, and / or - the thickness variation is at least 0.5 nm, at least 1.0 nm, preferably at least 1.5 nm, and / or - the first functional layer has a thickness of 11 to 13.5 nm, and / or - the second functional layer has a thickness of 12.5 to 14.5 nm.

[0132] [Fig.5] clearly shows that the moderate or absent colored drop effect is obtained when: - the first functional layer has a thickness greater than the third functional layer, and / or - the thickness variation is at least 0.5 nm, at least 1.0 nm, preferably at least 1.5 nm, and / or - the first functional layer has a thickness of 11 to 13.5 nm, and / or - the third functional layer has a thickness of 9.5 to 11.5 nm.

[0133] III. “Solar control” and colorimetry performances

[0134] The colorimetric performances and properties were determined by simulation.

[0135] [Tables5] Target Glazing Lam.lD Lam.2D Lam.3D Lam.4D GC (a,b) a<10; b<0 9.7; -6 9.7; -6.1 9.2; - 5.7 9.8; - 5.5 TL - 6.2 6.3 6.3 6.2 RL 8° <20% 14.9 13.8 14.2 15 a Rext*8° [-10;0] -2.7 -4.3 -3.3 -2.4 b Rext*8° [-10;5] -10.3 -10.8 -10.8 -9 a Rext*60° [-10;0] -6 -5.9 -5.7 -5.3 b Rext*60° [-10;5] -7.5 -7.8 -7.5 -6 A a*Rext (8° vs. 60°) < 3 -3.3 -1.6 -2.4 -2.9 A b*Rext (8° vs. 60°) < 3 2.8 3 3.3 3 RE <50% 44.9 44.9 45 44.9 TE <5% 3.2 3.3 3.2 3.2 TTS <14% 13.8 13.8 13.7 13.8 Vitrage Cible Lam.lC Lam.2C Lam.3C Lam.4C GC (a,b) a<10 ; b<0 9.7; -6 9.7; - 6.1 9.2; - 5.7 9.8; - 5.5 TL - 69 70.1 69.7 68.7 RL 8° <20% 17.2 16.1 16.4 17.2 a Rext*8° [-10;0] -3 -4.5 -3.6 -2.9 b Rext*8° [-10;5] -8.8 -9.1 -9 -7.6 a Rext*60° [-10;0] -6.6 -6.6 -6.4 -6.1 b Rext*60° [-10;5] -5.7 -5.8 -5.5 -4.4 A a*Rext (8° vs. 60°) < 3 -3.6 -2.1 -2.8 -3.2 A b*Rext (8° vs. 60°) < 3 3.1 3.3 3.5 3.2 RE <50% 45.9 45.9 46 45.8 TE <40% 33.4 33.6 33.4 33.1 TTS <40% 37.6 37.8 37.6 37.4

Claims

Claims

1. Material comprising a transparent substrate coated with a functional coating comprising successively from the substrate an alternation of three silver-based functional metal layers called, starting from the substrate, first, second and third functional layers, and four dielectric coatings called, starting from the substrate, Di1, Di2, Di3 and Di4 which each have an optical thickness E11, E12, E13 and E14, each dielectric coating comprising at least one dielectric layer, so that each functional metal layer is arranged between two dielectric coatings, characterized in that: - the ratio of the thickness of the second functional metal layer to the thickness of the first functional metal layer Ag2 / Ag1 is greater than or equal to 1.05,- the ratio of the thickness of the first functional metal layer to the thickness of the third functional metal layer Agl / Ag3 is greater than 1.05, - the ratio of the optical thicknesses Eo2 / Eo3 is greater than 1.00, - the first silver-based functional metal layer has a thickness of between 11 and 13 nm, and / or - the second silver-based functional metal layer has a thickness of between 13 and 14 nm, and / or - the third silver-based functional metal layer has a thickness of between 10.5 and 12 nm.,

2. Material according to claim 1 characterized in that at least the ratio of the thickness of the second functional metal layer to the thickness of the first functional metal layer Ag2 / Agl or the ratio of the thickness of the first functional metal layer to the thickness of the third functional metal layer Agl / Ag3 is greater than 1.10,

3. 3. Material according to any one of the preceding claims, characterized in that: - the dielectric coating Dil has an optical thickness Eol of between 50 and 80 nm, - the dielectric coating Di2 has an optical thickness Eo2 of between 160 and 180 nm, - the dielectric coating Di3 has an optical thickness Eo3 of between between 110 and 150 nm, - the dielectric coating Di4 has an optical thickness Eo4 between 70 and 90 nm.

4. 4. Material according to the preceding claim, characterized in that: - the ratio of optical thicknesses Eol / Eo2 is less than 0.40, - the ratio of optical thicknesses Eol / Eo3 is less than 0.40, - the ratio of optical thicknesses Eol / Eo4 is less than 1.

00.

5. 5. Material according to any one of the preceding claims, characterized in that each dielectric coating comprises a layer comprising silicon chosen from layers based on silicon nitride.

6. 6. Material according to the preceding claim characterized in that the sum of the physical thicknesses of all the layers comprising silicon in each dielectric coating is greater than 25% of the total thickness of the dielectric coating.

7. 7. Material according to any one of the preceding claims, characterized in that each dielectric coating located below a functional layer comprises a zinc oxide-based layer located below, in contact with or separated by a blocking layer, the functional layer.

8. 8. Material according to any one of the preceding claims, characterized in that each dielectric coating located above a functional layer comprises a zinc oxide-based layer located above, in contact with or separated by a blocking layer, the functional layer.

9. 9. Material according to any one of the preceding claims, characterized in that each dielectric coating located below a functional layer comprises a layer based on zinc and tin oxide located below and in contact with a layer based on zinc oxide.

10. Laminated glazing comprising the material according to any one of the preceding claims and at least one second substrate, the material and the second substrate are bonded together by means of a lamination interlayer.

11. Laminated glazing according to the preceding claim, characterized in that it comprises a face 1 located outside the building or vehicle which it equips, faces 2 and 3 in contact with the lamination interlayer and a face 4 inside the building or vehicle, the coating

12. functional silver-based coating is positioned on face 2. Laminated glazing according to the preceding claim characterized in that it further comprises a functional coating comprising a conductive oxide layer positioned on face 4.

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