Composite pane comprising an electrically switchable mirror element and a vacuum layer

Abstract

The invention relates to a composite pane comprising an outer pane (1) and an inner pane (2) which are connected together face-to-face, wherein the composite pane has an electrically switchable mirror element (3) between the outer pane (1) and the inner pane (2), and between the outer pane (1) and the electrically switchable mirror element (3) is an evacuated cavity (4).

Description

[0001] SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0002] Composite disc with electrically switchable mirror element and vacuum layer

[0003] The invention relates to a composite disc equipped with an electrically switchable mirror element and an evacuated cavity (a “vacuum layer”).

[0004] Glazing in buildings or vehicles serves to allow occupants a view of the outside environment and to ensure that light enters the interior. However, glazing always presents a challenge for thermal comfort in the interior – in summer, the interior heats up from the outside through the glazing, while in winter, it cools down through the glazing, primarily due to heat radiation and conduction. This heat transfer necessitates the use of cooling devices such as air conditioning at high outside temperatures and heating devices at low outside temperatures. This, in turn, increases energy consumption.

[0005] In electric vehicles, the consequences of significant heat loss are particularly critical because the automatic climate control (heating and cooling functions) increases energy consumption, leading to a shorter range before the next necessary battery charge. Furthermore, the waste heat from a combustion engine cannot be used for heating, meaning the heating system must also be electrically powered.

[0006] To reduce heat transfer through the glazing, it is known to apply transparent, IR-reflective coatings. Solar control coatings are known, which include IR-reflective silver layers to reflect the IR components of solar radiation. Low-E coatings are also known, with reflective properties in the mid-IR range. These reflect heat radiation emanating from the heated pane in summer and heat radiation emanating from the interior in winter. By way of example, reference is made to WO2019110172A1, which discloses a laminated glass pane with a solar control coating (for example, on the interior surface of the outer pane) and an emissivity-reducing coating (on the interior surface of the inner pane). SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0007] However, a large portion of the energy input is not caused by IR radiation, but by radiation in the visible spectral range. The incidence of visible light through the glazing can be reduced, for example, by using tinted glazing, which statically lowers light transmission. Glazing systems are also known in which the light transmission can be dynamically adjusted. Such glazing systems are, in particular, equipped with a functional element with electrically controllable optical properties.

[0008] The optical properties of such functional elements can be modified by applying an electrical voltage. The voltage is applied via a control unit connected to two surface electrodes of the functional element, between which the active layer or active layer system of the functional element is located. Examples of such functional elements are SPD (suspended particle device) functional elements, known, for example, from EP0876608B1 and WO2011033313A1. Another example is PDLC (polymer dispersed liquid crystal) functional elements, known, for example, from DE102008026339A1. Electrochromic functional elements are also known, for example, from US20120026573A1, WO2010147494A1, EP1862849A1, and W02012007334A1.However, these functional elements have the disadvantage of being highly light-absorbing in their non-transparent state, especially when this non-transparent state is heavily tinted (as with SPD or electrochromic functional elements, or so-called "guest-host" functional elements based on liquid crystals). This high absorption increases the emissivity of the laminated glass, i.e., the heat radiation emitted by it, which negatively impacts thermal comfort in the interior.

[0009] WO2018195458A1 discloses a building glazing with an evacuated cavity and an electrically switchable functional element arranged on the interior side. The functional element has adjustable transmission and / or scattering, which allows the glazing to be darkened or opaque. The functional element is, for example, a PDLC element.

[0010] From the subsequently published international application WO2024223925A1, a composite disc with an electrically switchable mirror element is known, which can be switched electrically from a transparent to a reflective state. SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0011] However, the glazing described so far only reduces the portion of heat transfer that is due to thermal radiation.

[0012] To reduce heat conduction, insulating glass units and vacuum insulating glass units are known, particularly in the field of architecture. In conventional insulating glass units, a spacer creates a gap between two panes of glass, which is filled with an inert gas. Vacuum insulating glass units (VIGs) consist of two spaced-apart panes of glass, with the space between them evacuated. Such vacuum insulating glass units are known, for example, from EP1978199A1 and W09804802A1. EP3878827A1 discloses a vehicle window designed as a vacuum insulating glass unit.

[0013] The present invention is based on the objective of providing an improved composite disc with reduced heat transmission and better thermal insulation.

[0014] The problem is solved according to the invention by a composite disk according to independent claim 1. Advantageous embodiments are set forth in the dependent claims.

[0015] The composite pane according to the invention comprises an outer pane and an inner pane, which are bonded together over a surface. The composite pane has an electrically switchable mirror element, which is arranged between the outer pane and the inner pane. An evacuated cavity is also arranged between the outer pane and the electrically switchable mirror element.

[0016] The electrically switchable mirror element can be switched from a transparent to a reflective state. In the reflective state, the incoming light is (at least partially or mostly) reflected, thus preventing it from entering the interior and contributing to heating. If thermal shielding is not required, or if heating the interior is even desired, for example, at low outside temperatures, the mirror element can be switched to the non-reflective, transparent state. The user can therefore actively control heat transfer and thus react flexibly to external conditions.Unlike other functional elements with electrically controllable optical properties, which primarily affect light transmission by changing light absorption or light scattering (such as SPD, PDLC, or electrochromic functional elements), the mirror element in its non-transparent state exhibits no significant light absorption that would otherwise lead to increased emissivity (heat radiation) of the laminated pane. The mirror element also has a comparatively short switching time (transition time between states) and a long service life. Furthermore, the laminated pane features an evacuated cavity, which can also be referred to as a vacuum layer. This vacuum layer provides the laminated pane with thermal insulation properties similar to vacuum insulating glass and reduces heat transfer due to conduction.The vacuum layer is arranged on the outside of the electrically switchable mirror element, so that the mirror element is protected from excessive heating at high ambient temperatures, which could damage the reflective film. The vacuum layer thus not only reduces heat conduction between the interior and the external environment via the laminated glass, but also protects the electrically controllable mirror element from thermal overload. The vacuum layer also acts as an acoustic insulator, reducing the amount of disruptive external noise penetrating the interior and eliminating the need for costly acoustic thermoplastic films. These are significant advantages of the present invention.

[0017] The laminated glass pane is designed to separate an interior space (for example, the interior of a vehicle or a building) from the external environment within a window opening. For the purposes of this invention, the term "inner pane" refers to the pane facing the interior space. The term "outer pane" refers to the pane facing the external environment. Both the outer and inner panes have an outer and an interior surface, and a circumferential side edge surface extending between them. For the purposes of this invention, the term "outer surface" refers to the main surface intended to face the external environment when installed. For the purposes of this invention, the term "interior surface" refers to the main surface intended to face the interior space when installed.The inner surface of the outer pane and the outer surface of the inner pane face each other and are connected (planar connection). The outer surface of the outer pane and the inner surface of the inner pane face away from each other. The outer pane and the inner pane are preferably arranged substantially parallel to each other. The outer pane and the inner pane are connected to each other via a multi-layered connection structure, wherein the electrically switchable mirror element and the evacuated cavity are part of the connection structure or are embedded within it.

[0018] The outer and inner panes are preferably made of glass, particularly preferably of soda-lime glass, as is common for window panes. However, one or both panes can also be made of other types of glass, such as quartz glass, borosilicate glass, or aluminosilicate glass, or of rigid, clear plastics, such as polycarbonate or polymethyl methacrylate. The thicknesses of the outer and inner panes are preferably from 0.5 mm to 5 mm, and particularly preferably from 1 mm to 3 mm, and are independent of each other. The outer and inner panes can optionally be thermally or chemically tempered, partially tempered, or not tempered, independently of each other.

[0019] The composite pane according to the invention has an evacuated cavity (vacuum layer) which improves the thermal insulation properties of the composite pane. The vacuum layer preferably borders the outer pane. Part of the composite pane thus forms a type of vacuum insulating glazing, with the outer pane preferably being part of this vacuum insulating glazing.

[0020] In a preferred embodiment, the evacuated cavity is formed between the outer pane and another pane. This second pane is arranged between the outer pane and the electrically switchable mirror element. The second pane is separated from the outer pane by spacers. In other words, the laminated pane is equipped with another pane, which is arranged between the outer pane and the mirror element and connected to the outer pane by spacers, so that an evacuated cavity exists between the outer pane and the second pane. The outer pane and the second pane thus form the vacuum insulating glass unit.

[0021] The additional disc has a thickness of, for example, 0.3 mm to 5 mm, preferably 0.3 mm to 3 mm, particularly preferably 0.5 mm to 2 mm, and most preferably 0.5 mm to 1.5 mm. The additional disc preferably has a thinner disc than the outer and inner discs. SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0022] The second pane is preferably made of glass. Soda-lime glass can also be used. In particular, a very thin second pane (for example, with a thickness of 0.5 mm to 1 mm) can also be made of aluminosilicate glass, which is preferably chemically tempered. Alternatively, the second pane can also be made of a rigid, clear plastic, such as polycarbonate or polymethyl methacrylate.

[0023] The gap (cavity) between the outer pane and the second pane preferably has a thickness of 0.1 mm to 1 mm, particularly preferably 0.2 mm to 0.5 mm. This achieves good thermal insulation without significantly increasing the thickness of the composite pane. The thickness of the gap corresponds to the distance between the facing surfaces of the outer pane and the second pane.

[0024] According to the invention, the cavity is evacuated. This means that a negative pressure prevails in the cavity, i.e., a pressure that is lower than the ambient pressure. The pressure in the cavity is preferably at most 100 mbar, more preferably at most 10 mbar. The pressure can, for example, range from 0.01 mbar to 100 mbar, preferably from 0.1 mbar to 10 mbar.

[0025] The spacers ensure that the outer pane and the inner pane do not deform despite the negative pressure between them. The spacers preferably keep the distance between the outer pane and the inner pane constant, so that the outer pane and the inner pane are arranged parallel to each other.

[0026] The spacers preferably comprise a plurality of spacer columns. The spacer columns are distributed (preferably uniformly) over the surface of the outer pane and the inner pane. The number of spacer columns and their spacing depend on the thickness of the panes and the negative pressure in the space between them. The thinner the panes (and the lower the pressure in the space between them), the more prone they are to deformation, necessitating a greater number of spacer columns. SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0027] The spacer columns are preferably transparent so as not to significantly impair the view through the laminated glass. They are preferably made of glass or plastic.

[0028] The spacers particularly preferably also include a circumferential spacer in an edge region between the outer pane and the second pane. The circumferential spacer extends around the perimeter of this edge region between the outer pane and the second pane. The evacuated space (cavity) is bounded by the outer pane, the second pane, and the circumferential spacer. The spacer is made, for example, of glass, plastic, metal, or a metal alloy.

[0029] To maintain the vacuum (more precisely, the negative pressure) in the cavity, the vacuum insulating glass unit, formed from an outer pane and another pane, preferably has a gas-tight edge seal. The surrounding spacer (if present) can itself act as an edge seal, or the vacuum insulating glass unit can be equipped with an additional edge seal, for example made of glass, a metal or metal alloy (e.g., stainless steel, silver, or copper), or a gas-tight plastic.

[0030] The second pane (more precisely, its surface facing away from the outer pane) is connected to the inner pane (more precisely, to its surface facing the outer pane) via an intermediate layer. The intermediate layer is formed from at least one bonding layer. This intermediate layer preferably contains the electrically switchable mirror element according to the invention.

[0031] In principle, it is also conceivable that the laminated glass unit contains a vacuum insulating glass unit consisting of an outer and an inner pane connected by spacers and featuring an intermediate, evaluated cavity, with the vacuum insulating glass unit positioned between the outer and inner panes. The outer pane is connected to the outer pane via an outer intermediate layer (consisting of at least one bonding layer), and the inner pane is connected to the inner pane via an inner intermediate layer (consisting of at least one bonding layer). SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0032] The electrically switchable mirror element is positioned between the second pane (or the inner pane of a vacuum insulating glass unit) and the inner pane. The mirror element can be in contact with the second pane or the inner pane, or it can be spaced apart from both.

[0033] The electrically switchable mirror element is suitable and intended to reflect light incident on the laminated pane from the outside (i.e., via the outer pane, from the external environment).

[0034] In a first preferred embodiment of the invention, the electrically switchable mirror element is designed as a coating and arranged on the outer surface of the inner pane facing the outer pane or the aforementioned intermediate layer. The further pane is connected to the inner pane via at least one (preferably exactly one) bonding layer, more precisely to the outer surface of the inner pane (or the mirror element applied thereto). The at least one bonding layer forms the aforementioned intermediate layer.

[0035] In the first preferred embodiment, the composite disc comprises, in the specified order: the outer disc, the spacers forming the cavity, the further disc, the bonding layer and the inner disc with the electrically switchable mirror element as a coating on its outer surface.

[0036] In a second preferred embodiment of the invention, the electrically switchable mirror element is designed as a film. This film is embedded in the aforementioned intermediate layer. It is connected to the further pane via (at least, preferably exactly) a first connecting layer, more precisely to the interior surface of the further pane facing away from the outer pane, and via (at least, preferably exactly) a second connecting layer to the inner pane, more precisely to the outer surface of the inner pane. The at least one first and the at least one second SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0037] The connecting layer with the intervening mirror element forms the aforementioned intermediate layer.

[0038] In the second preferred embodiment, the composite disc comprises, in the specified order: the outer disc, the spacers forming the cavity, the further disc, the first bonding layer, the electrically switchable mirror element as a film, the second bonding layer and the inner disc.

[0039] It is also conceivable that the electrically switchable mirror element is designed as a coating and arranged on the inner surface of the second pane, facing the inner pane or the aforementioned intermediate layer. The second pane, more precisely its inner surface (or the mirror element applied to it), is connected to the inner pane, more precisely to the outer surface of the inner pane, via at least one (preferably exactly one) bonding layer. This bonding layer forms the aforementioned intermediate layer. However, since the second pane is typically thinner than the inner pane and provides less stability, this configuration is generally less preferred.

[0040] In this embodiment, the composite pane comprises, in the specified order: the outer pane, the spacers which form the cavity, the further pane with the electrically switchable mirror element as a coating on its inner surface, the bonding layer and the inner pane.

[0041] In particularly preferred embodiments, the composite pane consists structurally of only the specified elements. The outer pane, the inner pane and / or the further SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0042] The disc (or the bonding layer(s) or further layers of the intermediate layer) may also be equipped with standard coatings or imprints.

[0043] The bonding layers serve to adhesively connect the components of the composite disc between which they are arranged. The bonding layers are preferably each composed of one or more thermoplastic layers. These thermoplastic layers can alternatively be referred to as thermoplastic sheets.

[0044] The thermoplastic layers are preferably based on polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), or polyurethane (PU), or on mixtures, copolymers, or derivatives thereof, particularly preferably on PVB. This means that the layer contains the said polymer to a large extent (proportion greater than 50% by weight). In addition to the polymer, the layer may contain other additives, such as plasticizers, UV absorbers, or stabilizers. Each thermoplastic layer is preferably formed from a thermoplastic film. The thickness of each film is preferably from 0.2 mm to 1 mm. For example, PVB films with standard thicknesses of 0.38 mm or 0.76 mm can be used.

[0045] The bonding layers can alternatively be designed as adhesive layers. Optically clear adhesives (OCAs) are preferred. This is particularly advantageous with regard to the aesthetic appearance of the vehicle roof window. OCAs are well known to those skilled in the art. They are characterized in particular by their high optical quality. They are especially common where high optical quality is necessary so that the adhesive layer is virtually invisible, for example, in displays or touch panels. Optically clear adhesives are characterized in particular by high light transmission and the fact that distortion-free visibility is possible. The optically clear adhesive is preferably a two-component polyurethane adhesive, a one-component acrylate adhesive, a one-component silicone adhesive, or a one-component acrylate hybrid adhesive.

[0046] In principle, a combination is also conceivable, whereby at least one bonding layer consists of at least one thermoplastic layer and at least one other bonding layer is designed as an adhesive layer. SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0047] It is possible for the electrically switchable mirror element to be present across the entire surface of the laminated glass, extending to its side edges. Alternatively, it is also possible for the mirror element not to extend to the side edges. In this case, no mirror element is present in the edge region of the laminated glass, which may be acceptable (especially if this edge region is located within an opaque masking area of ​​the laminated glass). If the mirror element is designed as a film, it can optionally be arranged within a cutout of another thermoplastic layer (capsule layer), which surrounds it like a frame. The frame-like thermoplastic capsule layer should have a width of no more than 10 cm, preferably no more than 5 cm.

[0048] The electrically switchable mirror element has a transparent state and a reflective state. The user can electrically select which state the mirror element is in, in particular by applying an electrical voltage to the mirror element. In the transparent state, the mirror element has a lower reflectance and correspondingly a higher transmittance than in the reflective state. Conversely, in the reflective state, the mirror element has a higher reflectance and correspondingly a lower transmittance than in the transparent state.

[0049] In the transparent state, the reflectance of the mirror element is preferably less than 20% (particularly preferably less than 10%, most preferably less than 5%). In the specular state, the reflectance of the mirror element is preferably more than 50% (particularly preferably more than 70%, most preferably more than 80%). This refers to the integrated reflectance in the spectral range from 380 nm to 780 nm, measured at an angle of 8° (to the surface normal) with light source A and a 2° detector (the 2° indicates the angle at which the light ray strikes the retina in the eye). The stated reflectance refers specifically to the surface of the mirror element facing the outer disk (outer surface), although typical mirror elements exhibit at least an approximately identical reflectance on both surfaces.

[0050] In the transparent state, the transmittance of the mirror element is preferably more than 60% (particularly preferably more than 70%, most preferably more than 80%). In the reflective state, the transmittance of the mirror element is preferably less than 50% (particularly preferably less than 30%, most preferably less than 20%). This refers to the integrated transmittance in the spectral range from 380 nm to 780 nm, measured at an angle of 0° (to the surface normal, orthogonal transmission) with light type A and a 2° detector.

[0051] It is also conceivable that the mirror element has several different reflective states, which differ in their reflectance. Furthermore, it is conceivable that the reflectance is continuously adjustable. Crucially for the present invention, at least one transparent and at least one reflective state is present, preferably with the specified values ​​for transmittance and reflectance.

[0052] The composite pane preferably has an external reflectance of less than 20% (particularly preferably less than 10%) when the mirror element is in the transparent state, and an external reflectance of more than 50% (particularly preferably more than 70%) when the mirror element is in the specular state. The external reflectance is the reflectance at the outer surface of the outer pane against incident radiation. It is measured as the integrated reflectance in the spectral range from 380 nm to 780 nm at an angle of 8° (to the surface normal) using light type A and a 2° detector.

[0053] The electrically switchable mirror element has an active layer or sequence of layers that provides the reflective properties in the mirrored state and is transparent in the transparent state. This active layer or sequence of layers is arranged between a first and a second surface electrode. When the composite disc is used as intended, the surface electrodes are connected to an external voltage source, allowing an electrical voltage to be applied to the active layer or sequence of layers via the surface electrodes. The surface electrodes and the active layer are typically arranged substantially parallel to the surfaces of the outer and inner discs.

[0054] The surface electrodes are preferably transparent, which, for the purposes of the invention, means that they have a light transmission in the visible spectral range of at least 50%, preferably at least 70%, and particularly preferably at least 80%. The surface electrodes preferably contain at least one metal, a metal alloy, or a transparent conducting oxide (TCO). The surface electrodes SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT can, for example, be based on silver, gold, copper, nickel, chromium, tungsten, indium tin oxide (ITO), gallium-doped or aluminum-doped zinc oxide, and / or fluorine-doped or antimony-doped tin oxide, preferably on silver or ITO. The surface electrodes preferably have a thickness of 10 nm to 2 pm, particularly preferably 20 nm to 1 pm, and most preferably 30 nm to 500 nm.

[0055] The surface electrodes are typically contacted with electrical connection cables that extend from the side edge of the composite disc and are connected to an external control unit. The electrical connection between the connection cable and the surface electrode can be made via a busbar located on the surface electrode. Such busbars can be implemented, for example, by strips of electrically conductive foil (such as copper foil) or by an electrically conductive imprint (such as silver-containing enamel).

[0056] Several variations are possible regarding the design of the active layer or layer sequence. In one embodiment, the active layer contains liquid crystals or is even based on liquid crystals. In the stress-free state, the liquid crystals exhibit, for example, a helical structure, which is reflective, thus achieving the specular state. When an electrical voltage is applied, the helical structure unfolds (or twists), so that the liquid crystals no longer reflect (significantly), thus achieving the transparent state. Typically, two such active layers are present and stacked on top of each other, each reflecting in one polarization direction, with the two polarization directions of the two active layers being rotated by 90° relative to each other. In this way, reflection of light of all polarizations can be achieved.In a further embodiment, an active layer sequence is present within which the migration of hydrogen or hydrogen ions can be induced by the applied voltage. One of these layers is typically a metallic layer (for example, based on lithium or a magnesium-nickel alloy), which is reflective in the hydrogen-free metallic state, thus achieving the specular state. An electrical voltage causes hydrogen to migrate into this layer, so that the layer is converted into a hydrogenated, non-metallic, and non-reflective state, thus achieving the transparent state. SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT.

[0057] Electrically switchable mirror elements are known per se and can be purchased prefabricated, particularly as films. Prefabricated electrically switchable mirror elements based on liquid crystals in film form are commercially available (e.g., from Kent Optronics). Mirror elements in the form of a coating are also known in the field (see, e.g., AIST, Japan).

[0058] If the mirror element is designed as a film, it comprises at least one polymeric carrier film on which the layer system consisting of the surface electrodes and the active layer (or sequence of layers) arranged between them is applied. Typically, the mirror element is a multilayer film and has two polymeric carrier films, with the layer system consisting of the surface electrodes and the active layer (or sequence of layers) arranged between the carrier films. The multilayer film then comprises, in the following sequence: a first carrier film – the first surface electrode – the active layer or sequence of layers – the second surface electrode – a second carrier film. The carrier films are preferably made of thermoplastic material, for example, based on polyethylene terephthalate (PET), polypropylene, polyvinyl chloride, fluorinated ethylene propylene, polyvinyl fluoride, or ethylene tetrafluoroethylene, particularly preferably based on PET.The thickness of the carrier films is preferably from 10 pm to 200 pm. The surface electrodes are typically provided as coatings on these carrier films.

[0059] In an advantageous embodiment, the composite pane according to the invention is provided with an IR-reflective coating. This coating can also be referred to as a solar control coating. The solar control coating serves to reduce the transmission of infrared components of solar radiation through the composite pane. To this end, the coating exhibits IR-reflective properties, particularly in the near-infrared (IR) range, for example, in the wavelength range from 780 nm to 3000 nm. The solar control coating is suitable for reflecting infrared components of solar radiation, so that the interior is heated less by direct heat radiation and the layers of the composite pane located behind the solar control coating (in the direction of the incoming radiation) are heated less.The latter, in turn, has a beneficial effect on the low emissivity of the laminated glass, which heats up less and therefore emits less thermal radiation. Overall, the heat or energy input through the laminated glass is reduced, and thermal comfort in the interior is improved. SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT.

[0060] The solar control coating can be applied, for example, to the inner surface of the outer pane, to a surface of the other pane, or to the outer surface of the inner pane. The solar control coating is preferably positioned closer to the outer pane than the electrically switchable mirror element in order to protect the latter from IR radiation as well. The solar control coating can also be applied to a carrier film (for example, PET-based, preferably with a thickness of 10 pm to 200 pm) which is located in the intermediate layer between two bonding layers (in particular, between two thermoplastic layers).

[0061] The solar control coating is particularly preferably applied to the interior surface of the outer pane facing the inner pane. This is particularly advantageous with regard to reducing the heating of the layers of the laminated pane behind it, because the solar control coating is located very far to the outside.

[0062] A solar control coating is typically a stack of thin films with at least one electrically conductive and IR-reflective layer based on a metal, particularly silver. It usually also contains dielectric layers that optimize the coating's optical properties (e.g., anti-reflective layers or layers to modify the structure of the metallic layer) and / or protect the metallic layer from corrosion. These dielectric layers can be based on materials such as silicon nitride, zinc oxide, tin-zinc oxide, silicon-metal mixed nitrides like silicon-zirconium nitride, zirconium oxide, niobium oxide, hafnium oxide, tantalum oxide, tungsten oxide, or silicon carbide.

[0063] The solar control coating is preferably applied to the entire surface of the glass pane, with the exception of a circumferential edge area and, optionally, a local area intended to ensure the transmission of electromagnetic radiation through the window pane as a communication, sensor, or camera window, and which is therefore not coated with the solar control coating. The circumferential uncoated edge area has, for example, a width of up to 20 cm and is preferably arranged entirely within an opaque masking area of ​​the laminated glass. It prevents direct contact between the solar control coating and the surrounding SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0064] An atmosphere is required to protect the solar control coating inside the laminated glass from corrosion and damage. Preferably, at least 80% of the glass surface is coated with the solar control coating.

[0065] The interior surface of the inner pane, facing away from the outer pane, is preferably provided with an emissivity-reducing coating. Emissivity-reducing coatings are also known as heat-radiation-reflecting coatings, low-emissivity coatings, or LowE (low emissivity) coatings. Emissivity is the measure that indicates how much heat radiation the pane, in its installed position, emits into an interior space compared to an ideal heat radiator (a black body). Emissivity-reducing coatings serve to prevent heat radiation from entering the interior space (IR components of solar radiation and, in particular, the thermal radiation of the pane itself) and also from radiating heat out of the interior space. They exhibit reflective properties with respect to infrared radiation, especially heat radiation in the spectral range of 5 pm to 50 pm (see also standard DIN EN 12898:2019-06).This effectively improves thermal comfort in the interior. The emissivity-reducing coatings can at least partially reflect the heat radiation emitted from the entire pane towards the interior at high outside temperatures and in direct sunlight. At low outside temperatures, they can reflect the heat radiation emitted from the interior, thus reducing the effect of the cold pane as a heat sink. The emissivity-reducing coating further enhances thermal comfort in the interior.

[0066] The emissivity-reducing coating is typically a transparent stack of thin films. The emissivity-reducing coating preferably comprises at least one, and more preferably exactly one, electrically conductive layer, which provides the IR-reflective properties. The conductive layer is preferably based on a transparent conductive oxide (TCO), in particular indium tin oxide (ITO), alternatively indium zinc mixed oxide (IZO), gallium-doped tin oxide (GZO), fluorine-doped tin oxide (FTO, SnO₂:F), antimony-doped tin oxide (ATO, SnO₂:Sb), or niobium-doped titanium oxide (TiO₂:Nb). Unlike metals, TCOs are not susceptible to corrosion, so they can be used on the exposed inner surface of the inner disc. In addition to the conductive layer, the coating typically has dielectric layers. SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0067] (for example, based on silicon oxide or nitride), which serve in particular to optimize the optical properties (for example, light transmission) or as barrier layers to regulate oxygen diffusion during the deposition of the coating.

[0068] The emissivity-reducing coating is preferably applied over the entire surface of the inner pane on the interior side, optionally with the exception of a surrounding uncoated edge area.

[0069] The laminated glass is designed as a glazing element and therefore has a transparent viewing area. This viewing area allows a view through the laminated glass. The laminated glass can be completely transparent, so that the viewing area encompasses the entire laminated glass. The laminated glass preferably has a light transmission of at least 6% in the viewing area. Light transmission here refers to the total transmission, determined by the procedure for testing the light transmittance of motor vehicle windows specified in ECE-R 43, Annex 3, Section 9.1. These specifications naturally refer to the laminated glass with the electrically switchable mirror element in its transparent state.

[0070] The transparent viewing area allows you to see through the laminated glass. However, the laminated glass can be tinted or colored to, for example, reduce glare for people inside or the transmission of heat radiation.

[0071] The laminated glass can also have an opaque masking area through which no light can pass or see through. Such a masking area is particularly common in vehicle windows. It is typically formed by an opaque printed coating on at least one of the surfaces of the inner and / or outer pane, for example, on the interior surface of the outer pane. An enamel printing paste containing glass frits and a pigment (especially black pigment) is printed onto the surface, for example, using a screen printing process, and then fired on. The masking area typically comprises a circumferential edge of the laminated glass, framing a central viewing area. However, the masking area can also include additional areas, which may, for example, act as cross braces for the frame-like edge.The composite disc exhibits SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT.

[0072] The masking area preferably has a light transmission of at most 1%, particularly preferably at most 0.1%, and in particular essentially 0%.

[0073] Alternatively, a masking area can also be formed by making a thermoplastic layer of the intermediate layer opaque or by embedding an opaque film or plate in the intermediate layer.

[0074] The electrically switchable mirror element and the evacuated cavity (the vacuum layer) preferably completely cover the viewing area of ​​the laminated glass. The same applies to the solar control coating and the emissivity-reducing coating, if present. However, particularly with regard to the solar control coating, local areas serving as communication or data transmission windows may not be coated. Complete coverage (except for any communication or data transmission windows) is advantageous for reducing heat transfer through the laminated glass. Typically, the electrically switchable mirror element, the vacuum layer, and, if applicable, the solar control coating and the emissivity-reducing coating extend beyond the viewing area into the masking area.They can extend independently of each other to the side edge of the composite pane or end in the masking area, with their edges being spaced away from the side edge of the composite pane.

[0075] The composite disc according to the invention is, in a preferred embodiment, a vehicle roof disc. The vehicle can be any means of transport for traffic on land, water, or in the air, for example, a ship, aircraft, rail vehicle, or motor vehicle (such as a passenger car or truck). The vehicle roof disc is most preferably a roof disc of a passenger car or truck.

[0076] The laminated glass is particularly preferred as the roof window of an electric vehicle. Due to its low heat transfer, the laminated glass according to the invention improves thermal comfort in the vehicle interior, thus reducing the need for heating (at low outside temperatures) and cooling (at high outside temperatures) devices. This saves energy, which is particularly advantageous for electric vehicles with regard to the operating time of the on-board battery.

[0077] Laminated glass can be flat, cylindrical, or spherically curved. Spherically curved laminated glass is common in passenger car windows. Flat laminated glass is particularly prevalent in architecture, but also in the automotive sector, for example, as glazing for buses or commercial vehicles (such as agricultural or construction vehicles).

[0078] The outer pane, the inner pane, the bonding layers, and the additional pane can be clear, tinted, or colored independently of one another. In the case of vehicle roof windows, strong tints are common, whereby the light transmission through the laminated glass (more precisely: through the viewing area) is reduced to below 50%, particularly below 20%. This is preferably achieved by a correspondingly tinted outer pane, inner pane, bonding layer, and / or additional pane, and especially preferably by a correspondingly tinted outer pane, inner pane, and / or bonding layer. The strong tint reduces solar radiation, thereby preventing the interior from heating up as much and avoiding glare. In a preferred embodiment, the inner pane is tinted or colored.

[0079] Another advantage of tinted layers is that they can mitigate any potential disturbance to the user, an external observer, or road traffic caused by the highly reflective laminated glass when the mirror element is in its reflective state. To reduce external reflection, a layer located on the outside of the mirror element is tinted, for example, the outer pane and / or the bonding layer between the mirror element and the outer pane. Preferably, the outer pane is tinted and the bonding layer is clear, because the tinting leads to heating due to radiation absorption, which then cannot propagate into the interior because the outer pane is thermally shielded from the interior by the vacuum layer.To reduce reflections from the interior, a layer located on the interior side of the mirror element is tinted, for example, the inner pane and / or the bonding layer between the mirror element (made of film) and the inner pane. SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT.

[0080] The composite disc can be manufactured by stacking the individual layers in the intended sequence into a layer stack and then laminating them together. This can be achieved using well-known methods, such as autoclave processes, vacuum bag processes, vacuum ring processes, calender processes, vacuum laminators, or combinations thereof. The bonding of the outer and inner discs via the intermediate layer typically occurs under the influence of heat, vacuum, and / or pressure.

[0081] The invention further comprises the use of a composite pane according to the invention as glazing for a vehicle, a building, or an interior space, or as a component of such glazing, in particular as a roof window pane (vehicle roof pane) of means of transport for travel on land, in the air, or on water. The vehicle roof pane can, in principle, be used in any land, air, or water vehicle, preferably in motor vehicles or rail vehicles, particularly preferably in passenger cars or trucks, especially in electric vehicles (electric passenger cars).

[0082] SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0083] The invention is explained in more detail with reference to a drawing and exemplary embodiments. The drawing is a schematic representation and not to scale. The drawing does not limit the invention in any way. It shows:

[0084] Fig. 1 is a top view of an embodiment of the composite disk according to the invention, Fig. 2 is a cross-section along XX' through the composite disk from Figure 1 ,

[0085] Fig. 3 shows a cross-section along XX' through a further embodiment of the composite disk according to the invention.

[0086] Figures 1 and 2 each show a detail of an embodiment of the composite glass according to the invention. The composite glass is designed as a vehicle roof window. It comprises an outer pane 1 and an inner pane 2, which are bonded together over their entire surface. The outer pane 1 and the inner pane 2 are made of soda-lime glass. The outer pane 1 has a thickness of 2.1 mm, and the inner pane 2 has a thickness of 1.6 mm. In its installed position, the outer pane 1 faces the external environment, and the inner pane 2 faces the vehicle interior.

[0087] The laminated glass pane has an opaque masking area M, which is arranged around the perimeter and surrounds a central transparent viewing area D like a frame. A black cover print 8 is applied to the inner surface of the outer pane 1, facing the inner pane 2, within the masking area M. The viewing area D allows a view through the laminated glass pane, while the opaque masking area M is opaque.

[0088] The laminated glass unit also includes an additional pane 5, which is a thin glass pane made of chemically tempered aluminosilicate glass with a thickness of, for example, 0.7 mm. This additional pane 5 is positioned between the outer pane 1 and the inner pane 2 and is connected to the outer pane 1 via a circumferential spacer 4a and a plurality of spacer columns 4b evenly distributed across its surface, creating a cavity 4 between the outer pane 1 and the additional pane 5 with a thickness of, for example, 0.3 mm. This cavity 4 is evacuated – the outer pane 1 and the additional pane 5 effectively form a vacuum insulating glass unit. The spacer columns 4b are made of glass or a transparent plastic. The circumferential spacer 4a is made of SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT.

[0089] The plastic is used. In addition, the circumferential spacer 4a is equipped with an edge seal (not shown) which seals the cavity 4 gas-tight.

[0090] The second pane 5 is connected to the inner pane 2 via an intermediate layer. An electrically switchable mirror element 3 is embedded in this intermediate layer. The mirror element 3 is designed as a multilayer film and is inserted into a cutout in a thermoplastic capsule layer 6c, which surrounds the mirror element 3 like a frame. The mirror element 3 with the capsule layer 6c is connected to the outer pane 1 via a first connecting layer, which is designed as a single thermoplastic layer 3a (first thermoplastic layer 6a), and to the inner pane 2 via a second connecting layer, which is designed as a single thermoplastic layer 3b (second thermoplastic layer 6b). The thermoplastic layers 6a and 6b are each made of a PVB film with a thickness of 0.76 mm, and the capsule layer 6c is made of a PVB film with a thickness of 0.38 mm.

[0091] A solar control coating 10 is applied to the interior surface of the outer pane 1, facing the inner pane 2. The solar control coating 10 completely covers the viewing area D and extends from there into the masking area M. In the masking area M, the solar control coating 10 can be positioned below or above the masking print 8. The solar control coating comprises at least one silver layer and exhibits reflective properties in the near-infrared range, thus reducing the amount of infrared radiation that can pass through the laminated pane.

[0092] An emissivity-reducing coating 20 is applied to the interior surface of the inner pane 2, the side facing away from the outer pane 1. The emissivity-reducing coating 20 covers the entire surface. At high outside temperatures, the emissivity-reducing coating 20 reflects the thermal radiation emitted by the heated laminated pane into the interior, and at low outside temperatures, it reflects the thermal radiation emitted from the interior. The emissivity-reducing coating 20 thus further reduces heat transmission through the laminated pane due to IR and thermal radiation.

[0093] The electrically switchable mirror element 3 has a transparent state and a reflective state. At high ambient temperatures and strong sunlight, the user can switch the mirror element 3 from the transparent to the reflective state by applying a suitable electrical voltage. This prevents (or significantly reduces) solar radiation from entering the vehicle interior, which consequently heats up less. This effect is due to reduced radiative heat transfer. Furthermore, the vehicle occupants are no longer blinded by sunlight. The evacuated cavity 4 reduces heat conduction through the laminated glass, similar to vacuum insulating glass. The combined effect of the evacuated cavity 4 and the mirror element 3 effectively improves thermal comfort in the interior.Furthermore, the mirror element 3 is protected from thermal overload by the evacuated cavity 4. The solar control coating 10 and the emissivity-reducing coating 20 further reduce radiation-based heat transfer, with the solar control coating 10 acting particularly on IR components of direct solar radiation and the emissivity-reducing coating 20 on the thermal radiation emanating from the heated laminated glass or the heated interior.

[0094] Figure 3 shows a further embodiment of the composite pane according to the invention. The outer pane 1 with the cover print 8 and the solar control coating 10, the further pane 5, the spacer 4a and the spacer column 4b, via which the further pane 5 is connected to the outer pane 1, and the inner pane 2 with the emissivity-reducing coating 20 are designed in the same way as in the embodiment of Figures 1 and 2.

[0095] The laminated glass differs from the previous design by the integration of the electrically switchable mirror element 3. This is arranged as a coating directly on the outer surface of the inner glass 2, facing the outer glass 1. The further glass 5 is connected to the inner glass 2 by an intermediate layer, which consists of a single bonding layer. This bonding layer is a single thermoplastic layer 6, which is made of a PVB film with a thickness of 0.76 mm. SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT

[0096] Reference symbol list:

[0097] (1) Outer pane

[0098] (2) Inner disc

[0099] (3) Electrically switchable mirror element

[0100] (4) evacuated cavity

[0101] (4a) circumferential spacer

[0102] (4b) Spacer columns

[0103] (5) another disc

[0104] (6) thermoplastic layer

[0105] (6a) first thermoplastic layer

[0106] (6b) second thermoplastic layer

[0107] (6c) thermoplastic capsule layer

[0108] (8) Cover printing

[0109] (10) Sun protection coating

[0110] (20) emissivity-reducing coating

[0111] (D) Viewing area of ​​the laminated glass

[0112] (M) Masking area of ​​the composite disc

[0113] X - X' Intersection line

Claims

25 SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT Patent claims 1. Composite pane comprising an outer pane (1) and an inner pane (2) which are connected to each other over a surface, wherein the composite pane has an electrically switchable mirror element (3) which is arranged between the outer pane (1) and the inner pane (2), and wherein an evacuated cavity (4) is arranged between the outer pane (1) and the electrically switchable mirror element (3).

2. Composite disc according to claim 1, wherein the evacuated cavity (4) is formed between the outer disc (1) and a further disc (5) which is arranged between the outer disc (1) and the electrically switchable mirror element (3) and is separated from the outer disc (1) by spacers (4a, 4b).

3. Composite pane according to claim 2, wherein the further pane (5) is made of soda-lime glass or chemically tempered aluminosilicate glass and preferably has a thickness of 0.5 mm to 1.5 mm.

4. Composite disc according to claim 2 or 3, wherein the spacers (4a, 4b) - a circumferential spacer (4a) in an edge area between the outer pane (1) and the other pane (5) and - comprise a plurality of spacer columns (4b).

5. Composite disc according to one of claims 2 to 4, wherein the electrically switchable mirror element (3) is arranged as a coating on the surface of the inner disc (2) facing the outer disc (1) and wherein the further disc (5) is connected to the inner disc (2) via a bonding layer.

6. Composite disc according to one of claims 2 to 4, wherein the electrically switchable mirror element (3) is designed as a film which is connected to the further disc (5) via a first connecting layer and to the inner disc (2) via a second connecting layer. SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT 7. Composite disc according to claim 5 or 6, wherein the bonding layers are formed as thermoplastic layers (6; 6a, 6b), preferably based on polyvinyl butyral (PVB), ethylene vinyl acetate (EVA) or polyurethane (PU), or as adhesive layers, preferably based on an optically clear adhesive (OCA).

8. Composite disc according to one of claims 1 to 7, wherein the evacuated cavity (4) has a thickness of 0.1 mm to 1 mm, preferably 0.2 mm to 0.5 mm, and a pressure of at most 100 mbar, particularly preferably at most 10 mbar.

9. Composite disc according to one of claims 1 to 8, wherein the electrically switchable mirror element (3) has a transparent state and a reflective state and wherein the state of the mirror element (3) depends on an electrical voltage applied to the mirror element (3), and wherein the reflectance of the mirror element (3) in the spectral range from 380 nm to 780 nm is less than 20% in the transparent state and more than 50% in the reflective state.

10. Composite disc according to claim 9, wherein the electrically switchable mirror element (3) has an active layer or sequence of layers between two surface electrodes and wherein - the active layer contains liquid crystals whose configuration is influenced by the applied electrical voltage, thereby realizing the transparent and the reflective state of the mirror element (3), or - the active layer sequence contains a metallic layer and the applied electrical voltage induces a migration of hydrogen ions in the layer sequence, so that the metallic layer is in a metallic state in the mirrored state of the mirror element (3) and in a hydrogenated state in the transparent state of the mirror element (3).

11. Composite pane according to one of claims 1 to 10, which is provided with a solar control coating (10) comprising at least one layer based on a metal, in particular silver, preferably on the surface of the outer pane (1) facing the inner pane (2). SAINT-GOBAIN SEKURIT FRANCE 2024337-WO-PCT 12. Composite disc according to one of claims 1 to 11, wherein the surface of the inner disc (2) facing away from the outer disc (1) is provided with an emissivity-reducing coating (20) which has at least one layer based on a transparent conductive oxide.

13. Composite pane according to one of claims 1 to 12, wherein the outer pane (1) and the inner pane (2) are made of soda-lime glass and preferably have a thickness of 1 mm to 3 mm.

14. Composite pane according to one of claims 1 to 13, wherein a transparent or translucent viewing area (D) is surrounded by an opaque masking area (M) in a frame-like manner and wherein the electrically switchable mirror element (3), the evacuated cavity (4) and optionally the solar control coating (10) and the emissivity-reducing coating (20) completely cover the viewing area (D).

15. Composite disc according to one of claims 1 to 14, which is a vehicle roof disc, preferably a roof disc of an electric vehicle.

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