Opaque vehicle roof panel with aerogel layer

Abstract

The present invention relates to a vehicle roof panel, comprising an outer panel (1) and an inner panel (2) that are joined face to face via an intermediate layer (3), the vehicle roof panel being opaque and an aerogel layer (6) being embedded in the intermediate layer (3).

Description

[0001] Opaque vehicle roof window with aerogel layer

[0002] The invention relates to a vehicle roof window equipped with an aerogel layer, as well as to a vehicle equipped therewith.

[0003] Some cars are equipped with roof windows, often simply referred to as "glass roofs." The roof window allows sunlight to enter the vehicle from above, creating a pleasant atmosphere inside and a feeling of "openness." However, the decision for or against a glass roof depends largely on the user's personal preferences. For example, some users find the view of the surroundings through the roof and the sunlight passing through the glass roof distracting or otherwise disturbing.

[0004] As a result, vehicle manufacturers typically offer two versions of their vehicles: one with a glass roof and one without. This requires them to provide two different vehicle bodies, and in some cases, interior components, such as upper lighting, antennas, and wiring, must be adapted to the two vehicle versions.

[0005] To simplify vehicle manufacturing, it is in principle possible to provide a single vehicle body with a roof opening into which, depending on the model, a transparent or opaque roof window is inserted. The version with the opaque roof window thus effectively creates a classic vehicle "without a glass roof." The vehicle manufacturer only needs to produce a uniform body for both versions, thereby reducing production costs and eliminating the need for production lines. DE202020104733U1 proposes a non-transparent roof window with at least one frosted glass pane for this purpose.

[0006] Compared to a traditional sheet metal roof (metal roof) formed by the vehicle body, such an opaque vehicle roof window has disadvantages, particularly with regard to thermal comfort in the vehicle. For example, the energy input due to solar radiation is significantly higher than with a sheet metal roof. The total solar energy radiated is essentially the sum of the directly radiated energy and the indirectly radiated energy as thermal radiation after the heating of window components (emissivity). This is typically characterized as the TTS value. While an opaque vehicle roof window can essentially reduce the directly radiated energy to zero, the problem of emissivity remains.The components of the roof window can be heated up considerably by solar radiation, which can be even more pronounced if the window components are heavily tinted compared to a transparent glass roof. They, in turn, emit heat radiation into the vehicle interior. If the vehicle interior heats up too much, this must be counteracted with air conditioning, which is not conducive to energy-saving operation.

[0007] There is therefore a need for improved opaque vehicle roof windows that reduce the energy input into the vehicle interior.

[0008] Aerogels are highly porous solids known for their very low thermal conductivity and thermal insulation properties. WO2012154602A1 discloses an insulating glazing unit with an aerogel layer. US2010146880A1 discloses a building roof panel consisting of two glass panes and an aerogel layer in between. EP3381881A1 discloses a composite panel consisting of two glass panes and an intermediate thermally insulating layer, which can be formed as an aerogel layer.

[0009] The present invention is based on the object of providing an improved opaque vehicle roof window which has a low heat input and ensures a high thermal comfort in the vehicle interior.

[0010] The object is achieved according to the invention by a vehicle roof window according to independent claim 1. Advantageous embodiments emerge from the subclaims.

[0011] The vehicle roof window according to the invention is designed as a composite pane. It comprises an outer pane and an inner pane, which are bonded to one another via an intermediate layer. The roof window is opaque. According to the invention, an aerogel layer is embedded in the intermediate layer. The vehicle roof window according to the invention is opaque overall and can thus replace a conventional opaque sheet metal roof, which is realized by the vehicle body itself. The vehicle manufacturer only needs to provide a vehicle body with an opening (window opening) in the roof, whereby either a transparent vehicle roof window or the opaque vehicle roof window according to the invention can be inserted into said opening. The vehicle manufacturing process is thereby simplified and the vehicle manufacturer can, in particular, save on production lines.The aerogel layer provides the opaque vehicle roof window according to the invention with thermally insulating properties, which reduces the energy input into the vehicle interior due to solar radiation, particularly in summer. Likewise, heat loss through the vehicle roof window is reduced, particularly in winter when outside temperatures are low. This significantly improves thermal comfort in the vehicle interior, and the need for air conditioning or heating is reduced, which both saves energy and reduces noise pollution in the vehicle. The aerogel layer also has acoustically insulating properties, so that less outside noise enters the vehicle interior, eliminating the need for costly acoustically insulating thermoplastic layers.The aerogel layer is very lightweight, so that the total weight of the vehicle roof window is also comparatively low. These are major advantages of the present invention.

[0012] The vehicle roof window is intended to separate the interior (vehicle interior) from the outside environment in an opening (roof opening) in the roof of a vehicle or a vehicle body. In the sense of the invention, the inner window refers to the window facing the interior. The outer window refers to the window facing the outside environment. The outer window and the inner window each have an outside surface and an inside surface and a circumferential side edge surface running between them. In the sense of the invention, the outside surface refers to the main surface which is intended to face the outside environment in the installed position. In the sense of the invention, the inside surface refers to the main surface which is intended to face the interior in the installed position.The interior-facing surface of the outer pane and the exterior-facing surface of the inner pane face each other and are connected to each other via the intermediate layer. The outer pane and the inner pane are preferably glass panes, particularly preferably made of soda-lime glass, as is common for window panes. However, one or both of the panes can in principle also be made of other types of glass, for example quartz glass, borosilicate glass or aluminosilicate glass, or of rigid, clear plastics, for example polycarbonate or polymethyl methacrylate. The thicknesses of the outer pane and the inner pane are preferably from 0.5 mm to 5 mm, particularly preferably from 1 mm to 3 mm. The outer pane and the inner pane can optionally be thermally or chemically toughened, partially toughened or not toughened, independently of each other.

[0013] The aerogel layer is embedded between the outer pane and the inner pane in the vehicle roof pane or its intermediate layer. The aerogel layer is preferably connected to the outer pane and the inner pane via a connecting layer. The vehicle roof pane according to the invention then comprises, in the order given: the outer pane, a connecting layer, the aerogel layer, a connecting layer, and the inner pane.

[0014] In a preferred embodiment, the vehicle roof window structurally consists only of the specified elements. The outer pane, the inner pane, and / or the connecting layers can also be provided with standard coatings or imprints.

[0015] The vehicle roof window preferably does not include any large-area electrical or other structural heat-insulating units. This is advantageous in terms of a simple design and a low overall thickness. The vehicle roof window particularly preferably does not include any photovoltaic cells, insulating glazing, or vacuum insulating glass.

[0016] The connecting layers serve to adhesively bond the components of the vehicle roof window between which they are arranged. The connecting layers are preferably formed as thermoplastic layers. The thermoplastic layers can also be referred to as thermoplastic layers.

[0017] The thermoplastic layers are preferably based on polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), or polyurethane (PU), or on mixtures or copolymers or derivatives thereof, particularly preferably based on PVB. This means that the layer predominantly contains the said polymer (a proportion greater than 50 wt.%). In addition to the polymer, the layer may contain further additives, for example, plasticizers, UV absorbers, or stabilizers. Each thermoplastic layer is preferably formed from at least one thermoplastic film. The thickness of each film is preferably between 0.2 mm and 1 mm. For example, PVB films with standard thicknesses of 0.38 mm or 0.76 mm can be used.

[0018] Because the aerogel layer has acoustically dampening properties, the use of so-called acoustic thermoplastic films can be eliminated. Instead, single-layer films can be used, which is significantly more cost-effective.

[0019] The connecting layers can alternatively be formed as adhesive layers, for example. So-called optically clear adhesives (OCAs) are preferred. This is particularly advantageous with regard to the aesthetic appearance of the vehicle roof window. OCAs are known as such to those skilled in the art. They are characterized in particular by high optical quality. They are particularly 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 low-distortion visibility is possible. The optically clear adhesive is preferably a 2-component polyurethane adhesive, a 1-component acrylate adhesive, a 1-component silicone adhesive, or a 1-component acrylate hybrid adhesive.Since the vehicle roof window according to the invention is opaque, the optical properties of the adhesive are not critical, so optically clear adhesives may not necessarily be used. Essentially, any adhesive can be used.

[0020] In principle, a combination is also conceivable, with one of the connecting layers being designed as a thermoplastic layer and the other connecting layer as an adhesive layer. The vehicle roof window according to the invention is opaque, i.e., it does not allow any visibility through it. The light transmittance of the vehicle roof window is preferably less than 2%, in particular 0%. Light transmittance here refers to the total transmittance, determined by the method specified in ECE-R 43, Annex 3, Section 9.1 for testing the light transmittance of motor vehicle windows. This is achieved by the vehicle roof window having at least one component that is opaque. The said opaque component is present over the entire surface, i.e., it covers the vehicle roof window over its entire area.

[0021] In a first embodiment of the vehicle roof window, the said opaque component is at least one of the bonding layers. The first bonding layer and / or the second bonding layer is / are opaque. For example, an opaque-tinted thermoplastic layer or film can be used, or an adhesive layer with opaque-tinting additives.

[0022] In a second embodiment of the vehicle roof window, the said opaque component is at least one of the panes. The outer pane and / or the inner pane is / are opaque. For example, an opaque-tinted glass pane can be used. Alternatively, the glass pane in question can have an opaque coating.

[0023] In a third embodiment of the vehicle roof window, the opaque component is the aerogel layer or comprises the aerogel layer. A naturally opaque aerogel can be used, or a naturally transparent or translucent aerogel can be provided with opaque-tinting additives. However, since the aerogel layer typically has less favorable optical properties than the panes or the bonding layers, which can lead to a less uniform aesthetic appearance, an opaque aerogel layer is less preferred than an opaque pane or an opaque bonding layer.

[0024] It is possible for the aerogel layer to be present over the entire surface of the vehicle roof window, i.e., to extend to the side edges of the vehicle roof window. Alternatively, it is also possible for the aerogel layer to be arranged in a section of a thermoplastic layer that surrounds it in a frame-like manner. In this case, there is no aerogel layer in the edge region of the vehicle roof window and therefore no thermal shielding, although this can be acceptable. The frame-like thermoplastic layer should have a width of no more than 10 cm, preferably no more than 5 cm. If the opacity of the vehicle roof window is provided by the aerogel layer, in this case the frame-like thermoplastic layer should also be opaque (and preferably in the same color as the aerogel layer). The said opaque component then comprises the aerogel layer and the thermoplastic layer surrounding it in a frame-like manner.

[0025] Since the opaque component, in advantageous applications, is intended to match the exterior color of the vehicle roof window to the vehicle paintwork, it is advantageous if the opaque component is positioned as far outside as possible. This creates a particularly uniform color impression of the vehicle. In the case of an opaque window or an opaque bonding layer, it is therefore particularly preferred if the outer window or the first bonding layer is opaque.

[0026] Combinations of the above-described configurations are also possible. For example, at least one of the bonding layers and at least one of the panes, preferably the outer pane and the first bonding layer, at least one of the bonding layers (preferably the first bonding layer) and the aerogel layer, at least one of the panes (preferably the outer pane) and the aerogel layer, or at least one of the bonding layers, at least one of the panes (preferably the outer pane and the first bonding layer), and the aerogel layer can be opaque.

[0027] It is also conceivable for the opaque component to be provided in the form of a dedicated film, which is integrated into one of the connecting layers, for example, arranged between two thermoplastic layers. The film can, for example, be a film based on polyethylene terephthalate (PET) that is tinted or colored to create an opaque finish.

[0028] In a further development of the invention, the vehicle roof window comprises an additional colored layer on the interior side of the said opaque component, which adapts the color of the roof window to the color scheme of the vehicle interior. This additional colored layer can, but does not have to, be opaque. For example, it is possible for the outer pane and / or the first connecting layer to be opaque, matching the color of the vehicle paintwork, and for the inner pane and / or the second connecting layer to be colored in a color that matches the vehicle interior.

[0029] The thickness of the aerogel layer can be selected according to the requirements of the specific application. In particular, the thermal conductivity of the aerogel (which in turn depends on the material, density, and porosity), the heat absorption of the laminated pane (which in turn depends on the other components of the laminated pane, in particular the material, thickness, and tinting of the outer pane, the inner pane, and the connecting layers), and the desired heat input (i.e., the desired TTS value, the total incident solar energy) play a role. The aerogel layer preferably has a thickness in the range of 0.1 mm to 10 mm, more preferably 0.2 mm to 8 mm, and in particular 0.5 mm to 6 mm. This achieves good results in typical applications.

[0030] The aerogel layer may optionally have an edge seal, for example in the form of a polymeric tape or a polymeric film.

[0031] Contrary to what the name initially suggests, aerogels are not gels, but highly porous solids. The name derives from the fact that aerogels are typically made from gels, whereby the liquid component of the gel is replaced by a gas without collapsing the gel structure, for example through supercritical drying or freeze-drying. Structurally, aerogels consist of a branching of particle chains (dendritic structure) with very many interstices (pores), particularly in the form of open pores. The particle chains have contact points with one another, so that the aerogel can be thought of as a stable, sponge-like network. The particle chains themselves often result from the fusion of, for example, spherical particles. A very high volume fraction of aerogels consists of pores, particularly open pores. Therefore, aerogels have a very low density.The aerogel layer according to the invention is therefore lightweight, so that the weight of the laminated pane is not significantly increased even by comparatively thick aerogel layers. Aerogels can also exhibit high optical transparency, which can be particularly advantageous for applications in glazing. Aerogels can be produced, for example, using sol-gel processes. Intercalations can be present in the pores, for example, to influence the mechanical, thermal, or optical properties of the aerogel layer. The pores are typically air-filled, apart from any intercalations. The aerogel layer according to the invention can also be referred to as an aerogel layer or as a layer or layer made of an aerogel or based on an aerogel.

[0032] For the purposes of the invention, porosity refers to the proportion of the pore volume to the total volume of the aerogel. The aerogel layer according to the invention is preferably formed from or based on an aerogel having a porosity of 50% to 99.98%, particularly preferably 80% to 99%, and most preferably 85% to 98%. The porosity can be determined by gas sorption measurement, in particular using carbon dioxide (CO2) as the measurement gas at a temperature of 273 K.

[0033] The pore size of the aerogel is preferably between 1 nm and 50 nm, particularly preferably between 10 nm and 40 nm. This refers in particular to the diameter of the typically approximately spherical pores. The pore size can also be determined using the aforementioned gas sorption measurement.

[0034] The density of the aerogel is preferably 0.16 mg / cm 3 up to 500 mg / cm 3 , particularly preferably 10 mg / cm 3up to 300 mg / cm 3 This refers to the bulk density based on the volume including the pore spaces, whereby the air in the pores is not included in the mass.

[0035] The particles that make up the network of particle chains typically have a size of 1 nm to 10 nm.

[0036] Aerogels can be formed from various materials (material of the particle chains). The aerogel of the aerogel layer according to the invention is preferably made of silicate, a polymer, carbon, cellulose, or a metal oxide. In principle, all polymers and metal oxides are suitable. Examples are polyimide for a polymer, and aluminum oxide, titanium oxide, zirconium oxide (all transparent and white or bluish), iron oxide (opaque, red, or yellow), chromium oxide (opaque, green, or blue), and vanadium oxide (opaque, olive green) for metal oxides. Strictly speaking, silicate aerosols do not have the chemical composition of a silicate, but rather SiO(OH). y (OR) z, where R is an organic residue and the parameters y and z depend on the manufacturing process. Nevertheless, they are generally referred to as such, and the term silicate is used accordingly in the context of the present invention. In English, the term "silica aerogel" is also commonly used (i.e., SiCh aerogel). Silicate aerogels, polymer aerogels, and cellulose aerogels are particularly preferred for the aerogel layer according to the invention. These aerogels are well researched and are already commercially available in large numbers.

[0037] The aerogel layer according to the invention can be structurally designed differently and integrated into the vehicle roof window, in particular

[0038] - as a so-called blanket or mat; this is understood to mean a composite material made of an aerogel (in particular silicate aerogel) and a material which influences the mechanical properties; the said material is in particular a fibre material (for example glass fibres); blankets are flexible and can be provided, for example, on rolls; such a mat can be made, for example, of an aerogel felt (in particular silicate aerogel felt);

[0039] - as a film; films are flexible and can also be provided, for example, on rolls; they can, for example, be formed from or based on a polymer aerogel, which can optionally have inclusions; an aerogel film can comprise a carrier film (for example made of PET or polyimide) on which an aerogel layer is arranged;

[0040] - as a rigid layer (“plate”);

[0041] - in the form of granules (with particle sizes in the millimeter range, for example) or particles (with particle sizes in the micrometer range, for example).

[0042] In principle, the vehicle roof window can also have multiple aerogel layers. However, in view of a simple structure and a low overall thickness, it is preferred that the vehicle roof window has only one aerogel layer.

[0043] In an advantageous embodiment, the interior-facing surface of the inner pane facing away from the intermediate layer is provided with an emissivity-reducing coating. Emissivity-reducing coatings are also known as heat-reflecting coatings, low-emissivity coatings, or LowE coatings (low emissivity). Emissivity is the measure that indicates how much heat radiation the pane emits into an interior space in the installed position compared to an ideal heat radiator (a black body). Emissivity-reducing coatings prevent heat from radiating into the interior (IR components of solar radiation and, in particular, the thermal radiation of the pane itself) and also prevent heat from radiating out of the interior. They exhibit reflective properties against infrared radiation, particularly against thermal radiation in the spectral range of 5 pm - 50 pm (cf.This effectively improves thermal comfort in the interior. At high outside temperatures and in direct sunlight, the emissivity-reducing coatings can at least partially reflect the heat radiation emitted by the entire pane toward the interior. 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 increases thermal comfort in the interior.

[0044] The emissivity-reducing coating is typically a transparent stack of thin films. The emissivity-reducing coating preferably has at least one, particularly preferably precisely one, electrically conductive layer, which provides the IR-reflecting 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 interior-side surface of the inner pane.In addition to the conductive layer, the coating typically comprises dielectric layers (e.g. based on silicon oxide or nitride), which serve in particular to optimize the optical properties (e.g. light transmission) or serve as barrier layers to regulate oxygen diffusion during the deposition of the coating.

[0045] In an advantageous embodiment, the interior-side surface of the outer pane facing the intermediate layer is provided with a sun protection coating. Sun protection coatings are also known as IR-reflective coatings or Solar ConfroZ coatings. The sun protection coating has reflective properties in the near-infrared range and is suitable for reflecting infrared components of solar radiation, so that the underlying layers of the composite pane are heated to a lesser extent. This, in turn, has a beneficial effect on the low emissivity of the vehicle roof window, which heats up less and therefore emits less thermal radiation. The sun protection coating is typically a stack of thin films with at least one layer based on a metal, particularly silver.In addition, dielectric layers are usually present that optimize the optical properties of the coating (e.g., anti-reflective layers or layers for influencing the structure of the metallic layer) and / or protect the metallic layer from corrosion. The dielectric layers can be based, for example, on silicon nitride, zinc oxide, tin-zinc oxide, silicon-metal mixed nitrides such as silicon zirconium nitride, zirconium oxide, niobium oxide, hafnium oxide, tantalum oxide, tungsten oxide, or silicon carbide. Alternatively, the sunscreen coating can also be applied to a carrier film (e.g., made of PET) embedded in the intermediate layer, preferably in the first connecting layer, for example, arranged between two thermoplastic layers.

[0046] The vehicle roof window can be flat, cylindrical, or spherically curved. Spherically curved composite panes are particularly common for roof windows on passenger cars.

[0047] The vehicle roof window can be coated with any desired coating, paint finish, or decoration, depending on the specific application. For example, digital printing, screen printing, or any type of color coating can be applied to the interior surface of the outer pane, facing the interlayer (before or after any bending process). This also allows the outer pane to be made opaque and in the desired color.

[0048] The vehicle roof pane can be manufactured by stacking the individual layers in the intended sequence to form a layer stack and then laminating them together. Known processes can be used for this purpose, for example, autoclave processes, vacuum bag processes, vacuum ring processes, calender processes, vacuum laminators, or combinations thereof. The outer pane and inner pane are typically joined under the influence of heat, vacuum, and / or pressure. The invention also encompasses the use of a vehicle roof pane according to the invention in means of transport for land, air, or water traffic, in particular as a roof pane of a passenger car or truck.

[0049] The invention further encompasses a vehicle equipped with a vehicle roof window according to the invention. The vehicle roof window is installed in an opening in the vehicle body in the roof area. The vehicle can, in principle, be any land, air, or water vehicle. The vehicle is preferably a motor vehicle or rail vehicle, particularly preferably a passenger car or truck.

[0050] To ensure a uniform appearance of the vehicle, the vehicle roof window preferably has the same color as the vehicle body or the vehicle paintwork. The color of the composite window is typically determined essentially by the color of the opaque component, which therefore preferably has the same color as the vehicle paintwork. The color of the roof window and the vehicle body can be assessed as the external reflection color, measured with a standard light source D65 (standard illuminant D65) at an angle of 8° (angle of incidence and observation) with a 2° detector. For the purposes of the invention, the roof window and the vehicle body have the same color if the color difference AE in the Lab color space (CIELAB of the International Commission on Illumination CIE, cf. standard EN ISO 11664-4) is less than or equal to 3, preferably less than or equal to 2.

[0051] However, it may also be intentionally desired that the vehicle roof window according to the invention visually contrasts with the bodywork and therefore has a different color. The vehicle roof window does not have to be uniformly colored. It (or the opaque component) can also be multicolored. This allows, for example, patterns, symbols, or national flags to be displayed. 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:

[0052] Fig. 1 is a plan view of an embodiment of the vehicle roof window according to the invention and

[0053] Fig. 2 shows a cross-section along XX' through the vehicle roof window from Figure 1.

[0054] Figures 1 and 2 each show a detail of an embodiment of the vehicle roof window according to the invention. The vehicle roof window is opaque overall, thus preventing any visibility. Such a vehicle roof window can simplify the vehicle manufacturing process. The vehicle manufacturer only needs to produce a single type of vehicle body with a roof opening. For models with a "glass roof," a transparent roof window can be inserted into this roof opening. For models without a "glass roof," the opaque roof window according to the invention can be used. If this is the same color as the vehicle's paintwork, it blends unobtrusively into the vehicle's appearance.

[0055] The vehicle roof window is designed as a composite pane. It consists of an outer pane 1 and an inner pane 2, which are connected to each other via an intermediate layer 3. The outer pane 1 and the inner pane 2 are made of untinted soda-lime glass, with the outer pane 1 having a thickness of, for example, 2.1 mm and the inner pane 2 having a thickness of, for example, 1.6 mm. In the installed position, the outer pane 1 faces the exterior of the vehicle, while the inner pane 2 faces the vehicle interior.

[0056] To improve thermal comfort in the vehicle interior, an aerogel layer 6 is embedded in the intermediate layer 3. The aerogel layer 6 is connected to the outer pane 1 via a first connecting layer 3a and to the inner pane 2 via a second connecting layer 3b. The connecting layers 3a, 3b are thermoplastic layers, each made from a PVB-based film with a thickness of 0.76 mm. The first connecting layer 3a is opaque due to a strong tint or color and gives the vehicle roof window its opacity. The second connecting film 3b is clear and untinted. The aerogel layer 6 has a thickness of 2 mm, for example. It is designed, for example, as a flexible film made from a transparent or translucent polymer aerogel.

[0057] Compared to a traditional sheet metal roof as part of the vehicle body, a vehicle roof window is heated up considerably by solar radiation. It then emits thermal radiation, which reduces thermal comfort in the interior. This problem is addressed according to the invention with the aerogel layer 6. The aerogel layer 6 has thermally insulating properties, so that the energy input into the vehicle interior is reduced. Conversely, at low outside temperatures, heat loss through the roof window is reduced. The aerogel layer 6 also has acoustically insulating properties, so that outside noise is better shielded. The aerogel layer 6 is very lightweight, so the overall weight of the vehicle roof window is not significantly increased.

[0058] In order to further reduce the energy input into the vehicle interior, the vehicle roof window has two coatings: a sun protection coating 4 on the interior-side surface of the outer pane 1 facing the intermediate layer 3 and an emissivity-reducing coating 5 on the interior-side surface of the inner pane 2 facing away from the intermediate layer.

[0059] The sun protection coating 4 has IR-reflective properties in the near IR range and reflects infrared components of solar radiation. The sun protection coating 4 therefore reduces the heating of the components of the vehicle roof window located behind it (seen from the outside) - in particular also the heavily tinted first connecting layer 3a. Since the roof window is heated to a lesser extent, it can in turn emit a low level of thermal radiation. The sun protection coating 4 is a stack of thin layers, including several silver layers, which are arranged alternately with dielectric layers or layer sequences. The emissivity-reducing coating 5 has reflective properties in the mid-IR range and has a particular effect on thermal radiation. In summer, it reduces the irradiation of thermal radiation from the roof window into the vehicle interior and in winter, it reduces heat loss through the roof window.The emissivity-reducing coating 5 is also a stack of thin layers, including an ITO layer and dielectric layers. The embodiment shown here is merely an example. It is not absolutely necessary for the opacity of the vehicle roof window to be provided by the first bonding layer 3a. Alternatively, the outer pane 1, the aerogel layer 6, the second bonding layer 3b, or the inner pane 2 could also be opaque. It is also possible for several elements of the vehicle roof window to be opaque, for example the outer pane 1 and the first bonding layer 3a or the first bonding layer 3a and the aerogel layer 6.

[0060] Examples

[0061] The energy input through the vehicle roof window was determined through simulations. To characterize this, the so-called thermal transmittance coefficient, commonly referred to as the U-value, was determined. The lower the U-value, the lower the thermal transmittance.

[0062] There were:

[0063] Example 1 shows a vehicle roof window according to the invention with an opaque first connecting layer 3a and a 5 mm thick aerogel layer 6;

[0064] Example 2 shows a vehicle roof window according to the invention with an opaque first connecting layer 3a and a 3 mm thick aerogel layer 6;

[0065] Comparative example 1 a transparent vehicle roof window without aerogel layer 6, the intermediate layer was formed from only a single 0.76 mm thick PVB film;

[0066] Comparative example 2: a black sheet metal roof with a thickness of 20 mm.

[0067] The roof panels of Examples 1 and 2 and Comparative Example 2 were designed analogously, with the outer pane 1, the inner pane 2, the coatings 4, 5, the material of the possible aerogel layer 6, and the connecting layers 3a, 3b being of the same design. The simulated U-values ​​are shown in Table 1. Although the examples according to the invention do not quite achieve the low thermal transmittance of the conventional sheet metal roof (Comparative Example 2), a significant reduction in thermal transmittance can be achieved compared to a roof panel without the aerogel layer 6.

[0068] Table 1

[0069] List of reference symbols:

[0070] (1) Outer pane of the laminated pane

[0071] (2) Inner pane of the laminated pane (3) Intermediate layer

[0072] (3a) first connecting layer of the intermediate layer 3

[0073] (3b) second connecting layer of the intermediate layer 3

[0074] (4) Sun protection coating

[0075] (5) emissivity-reducing coating (LowE coating) (6) aerogel layer

[0076] X - X' intersection line

Claims

Patent claims 1. Vehicle roof window, comprising an outer pane (1) and an inner pane (2) which are connected to one another via an intermediate layer (3), wherein the vehicle roof window is opaque and wherein an aerogel layer (6) is embedded in the intermediate layer (3).

2. Vehicle roof window according to claim 1, which comprises in the specified order: - the outer pane (1), - a connecting layer (3a), - the aerogel layer (6), - a connecting layer (3b), - the inner pane (2).

3. Vehicle roof window according to claim 2, wherein the first connecting layer (3a) and / or the second connecting layer (3b) is opaque, preferably the first connecting layer (3a).

4. Vehicle roof window according to claim 1 or 2, wherein the outer pane (1) and / or the inner pane (2) is opaque, preferably the outer pane (1).

5. Vehicle roof window according to claim 1 or 2, wherein the aerogel layer (6) is opaque.

6. Vehicle roof window according to one of claims 1 to 5, wherein the aerogel layer (6) has a thickness of 0.1 mm to 10 mm, particularly preferably of 0.2 mm to 8 mm, most preferably of 0.5 mm to 6 mm.

7. Vehicle roof window according to one of claims 1 to 6, wherein the aerogel layer (6) is formed on the basis of a silicate aerogel, polymer aerogel or cellulose aerogel.

8. Vehicle roof window according to one of claims 1 to 7, wherein the aerogel layer (6) is formed on the basis of an aerogel which has a porosity of 50% to 99.98%, preferably of 80% to 99%.

9. Vehicle roof window according to claim 2 or one of claims 3 to 8, if dependent on claim 2, wherein the first connecting layer (3a) and the second connecting layer (3b) are formed as thermoplastic layers, preferably each made of at least one film based on polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA) or polyurethane (PU).

10. Vehicle roof window according to claim 2 or one of claims 3 to 8, if dependent on claim 2, wherein the first connecting layer (3a) and the second connecting layer (3b) are formed as adhesive layers, preferably made of an optically clear adhesive (OCA).

11. Vehicle roof window according to one of claims 1 to 10, 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.

12. Vehicle roof window according to one of claims 1 to 11, wherein the surface of the inner pane (2) facing away from the intermediate layer (3) is provided with an emissivity-reducing coating (6).

13. Vehicle roof window according to one of claims 1 to 12, wherein the surface of the outer pane (1) facing the intermediate layer (3) is provided with a sun protection coating (4).

14. Vehicle equipped with a vehicle roof window according to one of claims 1 to 13.

15. The vehicle of claim 14, wherein the vehicle roof window has the same color as the vehicle paint.

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