Composite pane for an illuminatable glazing element

Abstract

The invention relates to a composite pane (100) for an illuminated glazing element (101), said composite pane comprising: - an outer pane (1), - an inner pane (2) which has an outer-side surface (III) facing the outer pane (1) and an interior-side surface (IV) facing away from the outer pane (1), - an adhesive intermediate film (3.1) which is arranged between the inner pane (2) and the outer pane (1) and has an outer-side surface (i) facing the outer pane (1) and an interior-side surface (ii) facing the inner pane (2) and - a low-refractive layer (4) which is attached to one of the surfaces (i, ii) of the adhesive intermediate film (3.1), wherein the refractive index of the low-refractive layer (4) is lower, at least by a value of 0.1, than the refractive index of the inner pane (2), wherein the adhesive intermediate film (3.1) has a layer thickness of 5 µm to 100 µm.

Description

[0001] Composite pane for an illuminable glazing element

[0002] The invention relates to a composite pane for an illuminable glazing element and to an illuminable glazing element with such a composite pane.

[0003] Illuminated glazing elements are well known as such. They are equipped with a light source whose light is coupled into a light guide, usually a glass pane, and spreads through total internal reflection. The light is often recoupled from the light guide by light-diffusing elements, thus creating the illumination. The shape of the light-diffusing elements can be freely selected, allowing illuminated surfaces of any shape, for example, a pattern, to be created. Illuminated glazing elements of this type are known, for example, from WO2014 / 060409A1 or WO2014 / 167291A1.

[0004] In the automotive sector, such illuminated glazing elements are particularly interesting as roof panels, but also as windshields or windows in trains or buses. The glazing element is typically designed as a laminated pane, with the light coupled into the inner pane. However, such illuminated glazing elements can also be used for other vehicle windows, windows in buildings and architecture, or in furnishings. The light-diffusing structures create illuminated surfaces that can be used to display aesthetically pleasing shapes and patterns or to display information, for example, directional arrows, status indicators, warning notices, price lists, or similar.

[0005] There are various known ways to couple the light from the light source into the light guide formed as a glass pane. The light source (typically an LED) can be arranged at the side edge, so that the light is radiated via the side edge into the glass pane and thus coupled. However, such coupling is often impossible, particularly because the side edge of the glass pane is usually ground to increase mechanical strength, which causes the side edge to become cloudy. Furthermore, an arrangement at the edge of the pane is difficult to achieve, since a glass pane with a light source arranged in this way loses stability.

[0006] Alternatively, the light source can be arranged in a recess in the glass pane (for example, in a feedthrough), so that the light is radiated into the glass pane via the side edge surface of the recess and thus coupled into the glass pane. However, drilling the recess makes the production of such a glazing element considerably more complex and is associated with the risk of a comparatively high level of rejects due to glass breakage.

[0007] US2020241189A1 proposes coupling light through a main surface of the glass pane. For this purpose, a reflective structure is attached to the surface of the glass pane facing away from the light source. The reflective structure has sections inclined relative to one another. The light source irradiates the reflective structure through the glass pane, and the light is reflected at the inclined sections in such a way that it spreads through the glass pane as a result of total internal reflection.

[0008] WO2008059170A2 discloses an illuminable glazing element using a porous coating. The porous coating has a lower refractive index than the inner pane. The coating primarily serves to reduce light reflection in building glazing or to increase the efficiency of solar cells. It is also intended to improve the optical appearance of the glazing element. WO2020156737A1 relates to a pane with a PDLC element. The pane is designed as a composite pane, with a PDLC element arranged between the inner and outer panes. The PDLC element serves not only as an optically switchable functional element but can also be used as a light-scattering structure for light coupled into the pane.A barrier layer, either as a film or coating on a pane, can help ensure that light is not coupled out through the outer pane into an interior space, but rather through the inner pane. WO2023209206A1, published after the priority date, discloses a composite pane capable of guiding light. To prevent unwanted light coupling out, a low-refractive-index layer is applied to the surface of the optical waveguide facing the intermediate layer.

[0009] In all generic solutions for coupling light, a significant portion of the light emitted by the light source is lost, since it is technically almost impossible to couple the light 100%, or even if the light is already coupled into the light guide, a partially undesired coupling of the light is possible.

[0010] The present invention is based on the object of providing an improved composite pane for an illuminated glazing unit, in which the light from a light source, which is intended to be coupled into the composite pane, can be used more efficiently, whereby the composite pane should be inexpensive to produce and should have a high level of stability.

[0011] The object of the present invention is achieved by a composite pane according to claim 1. Preferred embodiments emerge from the subclaims.

[0012] The composite pane according to the invention for an illuminated glazing element comprises at least one outer pane, one inner pane, an adhesive intermediate film, and a low-refractive-index layer. The adhesive intermediate film is arranged between the outer pane and the inner pane and has an outer surface facing the outer pane and an inner surface facing the inner pane. The inner pane has an inner surface facing away from the adhesive intermediate film and an outer surface facing the adhesive intermediate film. The low-refractive-index layer is applied to one of the surfaces of the adhesive intermediate film; this means that the low-refractive-index layer can be applied to the outer surface of the adhesive intermediate film or to the inner surface of the adhesive intermediate film.

[0013] The inner pane is designed such that it can conduct light, in particular visible light (400 nm to 800 nm). The inner pane can therefore be used as a light guide. The low-refractive index layer has a refractive index for light which is at least 0.1 lower than the refractive index of the inner pane. The adhesive intermediate film preferably has a refractive index that differs by less than 0.1, particularly preferably less than 0.05, from the refractive index of the inner pane if the low-refractive index layer is applied to the outer surface of the adhesive intermediate film. In particular, in this case the adhesive intermediate film has a refractive index that lies between the refractive index of the low-refractive layer and that of the inner pane. This means that the adhesive intermediate film can also be used as a light-conducting layer.

[0014] The laminated pane is intended to separate an interior space from the exterior environment in a window opening of a vehicle or building. In this context, “inner pane” within the meaning of the invention refers to the pane facing the interior (vehicle interior). “Outer pane” refers to the pane facing the exterior environment. However, the invention is not limited to this. The interior-side surface of the inner pane is simultaneously the interior-side surface of the laminated pane. The outer pane has an exterior surface facing away from the adhesive intermediate film and an interior-side surface facing the adhesive intermediate film. The exterior surface of the outer pane is simultaneously the exterior surface of the laminated pane.

[0015] For the purposes of the invention, "light guide" refers to a light-conducting medium, preferably a glass pane or a plastic pane, which is designed such that light can be coupled into the light guide using the effect of total internal reflection and is also suitable for guiding coupled-in light. The principle of light guidance using total internal reflection is generally known to those skilled in the art and is described in more detail, for example, in WO2008 / 047442A1, JP2011086547A, or JP2015043321A. The light guide is thus designed such that the light from a light source can be coupled into the light guide, here the inner pane, and can propagate therein.

[0016] The interior surface and the exterior surface of the inner pane represent interfaces to the adjacent medium. The exterior surface of the inner pane is, for example, the interface to the bonding intermediate film or to the low-refractive-index layer. The interior surface of the inner pane is, for example, the interface to the surrounding atmosphere. Typically, the medium adjacent to the interior surface (for example, the interior atmosphere) has a different refractive index than the inner pane. If the adjacent medium has a different refractive index than the inner pane, this results in a critical angle of total internal reflection, which is determined as a T= arcsinf— ), where ni is the refractive index of the optically denser medium and n2 is the refractive index of the optically rarefying medium. In the case of the interface between the inner pane and air, the refractive index of the inner pane is m and the refractive index of the air is n2. If light hits the interface at an angle of incidence that is greater than the critical angle, the light is completely reflected (total internal reflection). As is common in ray optics, the angle of incidence is the angle that the light beam incident on the surface makes to the surface normal of the surface at the point of impact. The angle of reflection is determined analogously to the surface normal, as is the critical angle of total internal reflection. The adhesive intermediate film serves as a thermoplastic intermediate layer or as a component of the thermoplastic intermediate layer. The intermediate layer bonds the outer pane and the inner pane together.

[0017] The inventors have surprisingly discovered that light can be coupled in particularly efficiently if at least one layer adjacent to the inner pane or the bonding intermediate film has a refractive index that is at least 0.1 lower than that of the inner pane. Due to the lower refractive index of the low-refractive-index layer, the resulting critical angle is smaller, thereby increasing the range in which light can be coupled in under total internal reflection. Light coupled into the light guide is also partially coupled into the bonding intermediate film, unless the low-refractive-index layer is arranged between the inner pane and the bonding intermediate film.The light-conducting medium comprising the inner pane can therefore also contain the adjacent bonding intermediate layers, whereby the light is reflected back and forth between the low-refractive-index layer and the interior-side surface of the inner pane (light conduction by total reflection).

[0018] In a preferred embodiment of the invention, at least one light-scattering element is arranged between the inner pane and the low-refractive-index layer. Preferably, at least two light-scattering elements, particularly preferably at least three light-scattering elements, and in particular at least five light-scattering elements, are arranged between the inner pane and the low-refractive-index layer. In addition to or independently of the aforementioned light-scattering elements, one or more light-scattering elements can be applied or incorporated on the interior-side surface of the inner pane or in the interior-side surface of the inner pane.

[0019] In a further preferred embodiment of the invention, at least one light-scattering element is applied to the interior surface or the exterior surface of the inner pane, preferably only the exterior surface.

[0020] Depending on the design of the composite pane, the at least one light-diffusing element can be arranged at various points within the composite pane. Some possible embodiments of the composite pane are shown below, with the sequence of layers given here also representing the sequence of the layer structure of the composite pane: 1. At least one light-diffusing element - inner pane - low-refractive-index layer - bonding intermediate film - outer pane,

[0021] 2. At least one light-scattering element - inner pane - adhesive intermediate film

[0022] - low-refractive layer - outer pane,

[0023] 3. Inner pane - At least one light-scattering element - low-refractive-index layer - adhesive intermediate film - outer pane,

[0024] 4. Inner pane - At least one light-scattering element - adhesive intermediate film

[0025] - low-refractive layer - outer pane or

[0026] 5. Inner pane - adhesive intermediate film - At least one light-scattering element

[0027] - low-refractive layer - outer pane.

[0028] For the purposes of the invention, a “light-scattering element” refers to an element suitable for coupling light out of the inner pane or out of the light-conducting medium (e.g., also the adhesive intermediate film). Light that is coupled into the inner pane and, if applicable, into surrounding adhesive intermediate films spreads out until it either strikes the side edge surface of the inner pane / adhesive intermediate films or strikes a light-scattering element and is coupled out there. The light-scattering elements are preferably arranged such that the coupled-in light is largely coupled out of the composite pane on the interior side, at the at least one light-scattering element. If coupled-in light strikes a light-scattering element, total internal reflection is interrupted, and the light is instead coupled out of the light-conducting medium.

[0029] The at least one light-diffusing element can be formed, for example, as a print. The light-diffusing element is preferably printed on the interior surface of the inner pane or the exterior surface of the inner pane. The print on the inner pane is preferably formed as a light-diffusing enamel. This enamel can be applied, for example, using a screen printing process. It preferably contains glass frits, which are fired into the surface of the inner pane, creating a roughened and therefore light-diffusing surface.

[0030] In a further embodiment, the at least one light-scattering element is a print which is applied to the adhesive intermediate film and / or to at least one further adhesive intermediate film which is arranged between the low-refractive-index layer and the inner pane. The at least one further adhesive intermediate film preferably has a refractive index which differs by less than 0.1 from the refractive index of the inner pane. Particularly preferably, the at least one further adhesive intermediate film has the same refractive index as the adhesive intermediate film. The print on the adhesive intermediate films can be realized by printing one of the surfaces of the intermediate films with a light-scattering printing paste. The print (printing paste) preferably contains no pigment and is therefore transparent. Alternatively, the transparent print can also contain pigments such as TiO2 pigments.In a further embodiment of the invention, the printing paste is opaque, semi-transparent or colored by dyes and / or color pigments.

[0031] In a particularly advantageous embodiment, the light-diffusing element is transparent, so that it does not significantly restrict visibility through the laminated pane. However, opaque or semi-transparent light-diffusing elements with pigments, such as white structures, are also conceivable. The light-diffusing element can also create a colored tint, i.e., at least not completely block visibility through the laminated pane, but rather create one or more color nuances.

[0032] The light-diffusing element appears as a luminous surface of the composite pane. This can be used, for example, to illuminate an interior, and in particular to display symbols or patterns that serve to convey information or may be intended for purely aesthetic reasons. The light-diffusing elements allow any shape or pattern to be realized.

[0033] In a preferred embodiment, the at least one light-scattering element can be provided as a film. Likewise, if necessary, further light-scattering elements present can be provided as a film. The film is arranged, for example, between the inner pane and the adhesive intermediate film. Alternatively or additionally, the film can also be arranged between the adhesive intermediate film and further adhesive intermediate films. The low-refractive index layer is always arranged closer to the outer pane than the at least one light-scattering element. Light-scattering elements as films can also be arranged within adhesive intermediate films. The films can be arranged within the respective layer, for example, by means of impressions. In this case, the respective layer completely encloses the film. This arrangement of the films can produce particularly efficient outcoupling.Light-diffusing elements of the inner pane, which is made of glass or plastic, can also be created by roughening the relevant surface of the inner pane. This roughening can be done mechanically (e.g., by grinding techniques) or by laser processing. Laser processing, particularly in the case of a laminated pane, has the advantage that the light-diffusing structure can also be incorporated into the finished laminated composite pane, even if it is intended to be located inside the composite pane, since the laser radiation can also be focused onto a plane inside the composite pane. Laser processing also makes it possible to create the light-diffusing structure inside the inner pane rather than on an outer surface.

[0034] The bonding intermediate film is preferably arranged on the inner pane. If the low-refractive-index layer is applied to the outer surface of the bonding intermediate film, the bonding intermediate film is preferably applied to the inner pane, i.e., in direct spatial contact with the inner pane. This spatial contact can be partially interrupted by light-scattering elements arranged between the bonding intermediate film and the inner pane. The low-refractive-index layer can be arranged between the bonding intermediate film and the inner pane, so that the low-refractive-index layer is, for example, in spatial contact with the inner surface of the bonding intermediate film and with the outer surface of the inner pane.The spatial contact between the low-refractive-index layer and the inner pane can be partially interrupted by light-scattering elements arranged between the inner pane and the low-refractive-index layer.

[0035] In a further preferred embodiment of the invention, at least one further adhesive intermediate film, preferably exactly one further adhesive intermediate film, is arranged between the inner pane and the adhesive intermediate film. The further adhesive intermediate film preferably has a refractive index that differs by less than 0.1 from the refractive index of the inner pane; preferably, the further adhesive intermediate film has the same refractive index as the adhesive intermediate film. The further adhesive intermediate film is preferably free of plasticizers. As a result, the further adhesive intermediate film has greater dimensional stability and rigidity, so that light-scattering elements are retained in better quality after lamination and, if designed as a print, can be printed on more effectively. It preferably has a layer thickness of 5 μm to 200 μm, particularly preferably 10 μm to 100 μm, in particular 25 μm to 75 μm.

[0036] During lamination, the bonding intermediate film and at least one additional bonding intermediate film fuse together to form an intermediate layer that bonds the inner pane to the outer pane. Additional bonding intermediate films can also be arranged between the bonding intermediate film and the outer pane.

[0037] Further preferred embodiments of the composite pane are shown below, whereby the sequence of layers given here also represents the sequence of the layer structure of the composite pane:

[0038] 1. Inner pane - further bonding intermediate film - low-refractive layer - bonding intermediate film - outer pane,

[0039] 2. Inner pane - further bonding intermediate film - bonding intermediate film - low refractive index layer - outer pane,

[0040] 3. Inner pane - two further bonding intermediate films - low refractive index layer - bonding intermediate film - outer pane or

[0041] 4. Inner pane - two further bonded intermediate films - bonded intermediate films - low refractive index layer - outer pane.

[0042] Preferably, if the low-refractive-index layer borders on the outer pane or the inner pane, an adhesive intermediate film is arranged between the low-refractive-index layer and the outer pane or the inner pane in order to ensure sufficient adhesion.

[0043] In the following, further preferred embodiments of the composite pane with at least one light-scattering element and a further adhesive intermediate film are shown, whereby the sequence of the layers given here also represents the sequence of the layer structure of the composite pane:

[0044] 1. At least one light-scattering element - inner pane - further bonding intermediate film - low-refractive-index layer - bonding intermediate film - outer pane,

[0045] 2. At least one light-diffusing element - inner pane - further bonding intermediate film - bonding intermediate film - low-refractive-index layer - outer pane, 3. Inner pane - at least one light-diffusing element - further bonding intermediate film - low-refractive-index layer - bonding intermediate film - outer pane,

[0046] 4. Inner pane - At least one light-scattering element - further bonding intermediate film - bonding intermediate film - low-refractive-index layer - outer pane or

[0047] 5. Inner pane - further bonding intermediate film - bonding intermediate film - at least one light-scattering element - low-refractive-index layer - outer pane.

[0048] Preferably, if the low-refractive-index layer borders the outer pane or the inner pane, an adhesive intermediate film is arranged between the low-refractive-index layer and the outer pane or the inner pane in order to ensure sufficient adhesion.

[0049] The adhesive intermediate film and any additional adhesive intermediate films that may be present preferably contain polyvinyl butyral (PVB), ethylene-vinyl acetate copolymers (EVA), thermoplastic polyurethanes (TPU), polyacrylate compounds (e.g., polyacrylate or polymethylacrylate), and / or silicone. The adhesive intermediate film is preferably free of polyethylene terephthalate (PET). The adhesive intermediate film and any additional adhesive intermediate films that may be present are preferably optically clear adhesives (OCA). Particularly preferably, the adhesive intermediate film and any additional adhesive intermediate films that may be present are based on PVB, EVA, TPU, polyacrylate compounds (e.g., polyacrylate or polymethylacrylate), or silicone, and in particular, they consist thereof.If additional intermediate bonding films are used in addition to the intermediate bonding film, these can be different or identical to the intermediate bonding film. These materials are ideally suited as adhesive layers for bonding panes in a composite pane. Intermediate bonding films based on PVB preferably have a refractive index of 1.48.

[0050] If something is "based" on a polymeric material, it consists predominantly of this material, i.e., at least 50%, preferably at least 60%, and especially at least 70%. It may therefore also contain other materials such as stabilizers or plasticizers.

[0051] The adhesive intermediate film and any additional adhesive intermediate films present are preferably free of plasticizers. Typical plasticizers are aliphatic diesters of tri- or tetraethylene glycol, e.g. triethylene glycol bis-(2-ethylhexanoate). Suitable plasticizer-free PVB films are, for example, MovitalO films, available from Kuraray. The adhesive intermediate film particularly preferably has a plasticizer content of less than 5%, preferably less than 1%, and in particular is free of plasticizers, whereas, if present, the additional adhesive intermediate films preferably each have a plasticizer content of at least 15% by weight. Alternatively, the adhesive intermediate film has a plasticizer content of at least 15% by weight and, if present, at least one additional adhesive intermediate film has a plasticizer content of less than 5%, preferably less than 1%, and in particular is free of plasticizers.Due to the absence of plasticizers, the intermediate film exhibits better dimensional stability during lamination, allowing the patterns of the light-scattering elements to be retained with higher quality. Furthermore, the plasticizer-free adhesive intermediate film has a smoother surface with less roughness, allowing the low-refractive-index layer to be applied with a more homogeneous layer thickness. A further advantage is that no or fewer plasticizers can diffuse out, which can impair the quality of the laminated pane, especially if the laminated pane has one or more functional elements, especially unsealed ones.

[0052] According to the invention, the adhesive intermediate film has a layer thickness of 1 μm to 100 μm, preferably of 10 μm to 75 μm, in particular of 25 μm to 50 μm. The lower layer thickness enables the use of films with a lower plasticizer content. This makes the adhesive intermediate film better suited for depositing the low-refractive-index layer onto it. If the adhesive intermediate film is thicker, this can result in the composite pane having to be made thicker, since other layers with a tendentially higher plasticizer content must then also be correspondingly thicker. This can impair the stability of the composite pane. The lower thickness also saves material costs.If further adhesive intermediate films are present, each further adhesive intermediate film has a layer thickness of 1 μm to 1000 μm, particularly preferably from 1 μm to 100 μm, very particularly preferably from 10 μm to 75 μm, in particular from 25 μm to 50 μm. The thickness of the entire intermediate layer after lamination of the layer stack to form the composite pane is preferably from 0.1 mm to 2 mm, particularly preferably from 0.25 mm to 1 mm, typically 0.38 mm or 0.76 mm. In this context, intermediate layer means all layers and elements arranged between the inner pane and the outer pane, including all functional elements, films and other layers that may be present. The adhesive intermediate film preferably has a refractive index that deviates from the refractive index of the inner pane by less than 0.1, particularly preferably less than 0.08, very particularly preferably less than 0.05, in particular less than 0.03.If further adhesive intermediate films are arranged between the inner pane and the low-refractive-index layer, these preferably have a refractive index that deviates from the refractive index of the inner pane by less than 0.1, more preferably less than 0.08, most preferably less than 0.05, and in particular less than 0.03. The small differences in the refractive index lead to improved light coupling into the inner pane and the surrounding intermediate films. In the case of adjacent layers with small differences in refractive index, the coupled-in light is largely not totally reflected between the adjacent layers, but spreads out within the adjacent layers as if they represented a continuous medium.In other words, light coupled into the composite pane according to the invention propagates largely through all bonded intermediate films and the inner pane, which are arranged between the interior-facing surface of the inner pane and the low-refractive-index layer. Thus, the light is largely only totally reflected at the interfaces between the inner pane and the interior, the interface between the inner pane and the low-refractive-index layer, or the interface between the (further) bonded intermediate film and the low-refractive-index layer.

[0053] According to the invention, the low-refractive-index layer is applied to the interior surface of the bonding intermediate film or to the exterior surface of the bonding intermediate film. If the low-refractive-index layer is applied to the exterior surface of the bonding intermediate film, the bonding intermediate film is also intended to act as a light-conducting medium to guide a portion of the light coupled into the inner pane of the laminated pane. If the low-refractive-index layer is applied to the interior surface of the bonding intermediate film, the low-refractive-index layer can preferably also be in direct spatial contact with the exterior surface of the inner pane.The low-refractive-index layer is therefore arranged between the inner pane and the bonding intermediate film, without anything being arranged between the inner pane and the low-refractive-index layer, with the exception of any light-scattering elements that may be present. This means that the light coupled into the inner pane is largely only coupled into the inner pane due to the large differences in refractive index. In such a case, the bonding intermediate film preferably does not need to be light-conducting and can, for example, be tinted, which reduces material costs. Alternatively, and regardless of whether the low-refractive-index layer is arranged on the interior surface of the bonding intermediate film or the exterior surface of the bonding intermediate film, further bonding intermediate films can be arranged between the bonding intermediate film and the inner pane.

[0054] In a preferred embodiment of the invention, the low-refractive-index layer is applied to the interior-side surface of the adhesive intermediate film, and at least two further adhesive intermediate films, preferably exactly two further adhesive intermediate films, are arranged between the intermediate film and the inner pane. Preferably, one of the two further intermediate films is free of plasticizers; particularly preferably, the further intermediate film of the two adhesive intermediate films that is arranged closer to the inner pane is free of plasticizers. In particular, light-scattering elements are arranged between the two further adhesive intermediate films. This has the advantage that the light-scattering elements are arranged within the composite pane without any contact with the low-refractive-index layer or the inner pane, which increases the stability and quality of the composite pane.

[0055] The low-refractive-index layer preferably has a refractive index of at most 1.50, more preferably of at most 1.45, and especially of at most 1.40. The lower the refractive index, the smaller the critical angle above which total reflection is possible. In other words, less light is lost through the low-refractive-index layer than with layers with a higher refractive index; instead, total reflection occurs at the interface even at lower angles of incidence.

[0056] In a preferred embodiment of the invention, not just one low-refractive-index layer is applied to the bonding intermediate film, but at least two low-refractive-index layers, preferably at least three low-refractive-index layers, are applied to the bonding intermediate film. The multiple low-refractive-index layers are applied as a layer stack on the interior surface or the exterior surface of the bonding intermediate film. This improves the homogeneity of the low-refractive-index layer, which reduces light loss through the low-refractive-index layer.

[0057] The low-refractive-index layer can be an organic, cross-linked, or thermoplastic polymer, or alternatively, a mineral layer. In a preferred embodiment of the invention, the low-refractive-index layer is formed as a varnish, which can be obtained from a photocrosslinkable resin, optionally mixed with photoinitiators. Alternatively, the resin is thermally crosslinkable. It can, for example, be formed from a two-component mixture. A layer of crosslinkable resin is deposited on the bonding intermediate film.

[0058] In particular, the low-refractive-index layer comprises or consists of a cross-linked polymer matrix with a refractive index of at most 1.42, preferably at most 1.40, in particular at most 1.3, wherein the matrix is ​​preferably formed from polymers based on polyacrylate, particularly preferably based on fluorine-functionalized polyacrylate. The refractive index of the low-refractive-index layer can be reduced by means of fluorine functionalization. The use of polyacrylate as a material for the low-refractive-index layer is advantageous because acrylate compounds can be efficiently cross-linked by photopolymerization, thereby simplifying the production of the low-refractive-index layer. In particular, the polymer matrix is ​​formed from urethane acrylate or fluorourethane acrylate or fluorosilicone acrylate.Alternatively, the polymer matrix can also be based on silicone, polydimethylsiloxane, epoxy polymer, polyepoxides, polyurethane, polyvinyl acetate, or polyester. Preferably, the low-refractive-index layer does not contain free silicone or silicon compounds (sources of surface contamination). Any silicone or silicon compounds present are therefore an integral part of the polymer matrix and are not removed from the low-refractive-index layer, for example, in a deaeration process during lamination.

[0059] For the purposes of the invention, "polyacrylate" refers to a polymer containing repeating units of acrylic compounds, i.e., whose monomers belong to the acrylic group. The repeating unit can be substituted or unsubstituted within the permissible valence range. The polyacrylate can be a homopolymer or a copolymer, i.e., composed of only one type of monomer or of several different types of monomers. In particular, "polyacrylate" refers to polymers such as polymethylacrylate, polyethyleneacrylate, polypropylmethacrylate, polymethylmethacrylate, polyethylenemethacrylate, polyethylmethacrylate, or polypropylmethacrylate. Polyacrylate can also refer to mixtures of such polymers.

[0060] For the purposes of the invention, "epoxy polymer" means that the polymer contains epoxy compounds. The epoxy polymer preferably comprises one or more compounds from the group consisting of bisphenol A epoxy resins, halogenated phenol epoxy resins, phenol epoxy resins, cycloaliphatic epoxy resins, and bisphenol S epoxy resins, particularly preferably in a proportion of at least 1 wt.%, in particular at least 5 wt.%.

[0061] The low-refractive-index layer can in particular be a coating which is

[0062] • Flow coating,

[0063] • Dip coating,

[0064] • Screen printing,

[0065] • Digital printing (English: “digital printing” or

[0066] • Inkjet printing is applied to the bonding intermediate film. The application of the low-refractive-index layer can be carried out in particular by spin coating, film puller 1), curtain or slot die coating, Meyer bar printing or gravure printing. The low-refractive index layer is preferably applied as a UV-photocrosslinkable substrate and then polymerized using UV radiation. Alternatively, it is also possible to apply two components that react with each other spontaneously (exergonic reaction) or under the influence of heat (endergonic). This is a two-component formulation that crosslinks to form a polymer through a chemical reaction. Crosslinking using UV radiation is preferred because the crosslinking is faster and the process is more cost-effective / compact than with a chemical reaction. In particular, components that polymerize under the influence of UVA radiation (wavelength range from 315 nm to 380 nm) are used.

[0067] In a preferred embodiment, the low-refractive-index layer contains a polymer that can be produced by photopolymerization, particularly preferably photopolymerization initiated by UV radiation. The low-refractive-index layer is preferably based on a polyacrylate (e.g., a urethane acrylate resin) or a silicone compound.

[0068] The low-refractive-index layer preferably comprises (nano-)porosities and / or (nano-)particles with a refractive index of less than or equal to 1.3. The porosities and / or particles are preferably hollow and have a diameter of at most 300 nm or in particular at most 100 nm. More preferably, the low-refractive-index layer comprises hollow silicon dioxide nanoparticles. Preferably, the optical insulation coating does not contain free silicone or volatile silicon compounds (a source of surface contamination). The low-refractive-index layer preferably has at most 60 vol.%, more preferably at most 50 vol.%, most preferably at most 40 vol.%, in particular at most 30 vol.% of (nano-)porosities and / or (nano-)particles with a refractive index of less than or equal to 1.3.

[0069] In a particularly preferred embodiment of the invention, the low-refractive-index layer comprises a polymer matrix of polyacrylate, with silicon dioxide-based particles embedded in the polymer matrix. In particular, the low-refractive-index layer consists of a polymer matrix of polyacrylate, with silicon dioxide-based particles embedded in the polymer matrix. In this way, a refractive index of less than 1.4 can be efficiently achieved.

[0070] In a further embodiment of the invention, the low-refractive-index layer is formed on the basis of a mineral layer. The low-refractive-index layer preferably consists of a mineral layer. In particular, the low-refractive-index layer is a sol-gel layer based on porous silicon dioxide or a layer based on oxides, preferably based on silicon dioxide, which was deposited on the bonding intermediate film by physical vapor deposition (PVD) such as magnetron sputtering. The low-refractive-index layer, in particular if it consists predominantly of silicon dioxide, can have dopants, for example dopants of aluminum. If the low-refractive-index layer is formed on the basis of porous silicon dioxide, the pores of the silicon dioxide preferably have an average pore diameter of 10 nm to 200 nm, particularly preferably 30 nm to 200 nm.In addition to or independently of the preferred pore diameter, the porous silicon dioxide preferably has a porosity of 40% to 85%, most preferably 50% to 74%. The porosity indicates the pore volume relative to the total volume of the porous silicon dioxide. In these ranges, a particularly suitable and homogeneously distributed refractive index is achieved.

[0071] If the low-refractive-index layer is formed on the basis of a mineral layer, it consists predominantly of the mineral layer, in particular essentially of this material in addition to any impurities or doping.

[0072] The low-refractive-index layer comprises at least one individual layer, but can also comprise multiple layers, for example, 2, 3, or 4 individual layers. In particular, the low-refractive-index layer consists of exactly one layer. If the low-refractive-index layer comprises multiple individual layers, the individual layers can be formed differently. The layer thickness of the low-refractive-index layer is preferably at most 1 mm, particularly preferably less than 50 pm, in particular less than 400 nm. If the low-refractive-index layer comprises multiple layers, the specified layer thickness refers to the combined layer thickness of all individual layers of the low-refractive-index layer.

[0073] If the low-refractive-index layer is a mineral layer (e.g. based on SiC>2), it can be applied by physical or chemical vapor deposition, i.e., a PVD or CVD coating (PVD: physical vapor deposition, CVD: chemical vapor deposition), or, for example, using the sol-gel process. Such coatings can be produced with particularly high optical quality and with particularly low thickness. If more than one low-refractive-index layer is applied to the bonding intermediate film, the individual layer(s) present are applied consecutively, i.e., one after the other. The application of layers using the sol-gel process is known to those skilled in the art and can be found, for example, in WO2021209201 A1. The volume fraction of the pores of porous silicon dioxide can be limited and controlled by production using a sol-gel process.

[0074] A PVD coating can be a coating applied by cathode sputtering, particularly a coating applied by magnetic field-assisted cathode sputtering (magnetron sputtering). Preferably, the low-refractive-index layer, if a mineral layer (e.g., SiO2), is applied by magnetron sputtering. Magnetron sputtering can efficiently create a homogeneous layer just a few nanometers thick.

[0075] If the low-refractive-index layer is applied using chemical vapor deposition, this is preferably done using plasma-enhanced chemical vapor deposition (PECVD), particularly at atmospheric pressure (APCVD). The advantage of plasma-enhanced chemical vapor deposition is the speed of deposition combined with high layer homogeneity compared to other processes. Silicon oxide, in particular, can be applied homogeneously and efficiently to a substrate using this process.

[0076] The low-refractive-index layer preferably extends over at least 80%, particularly preferably at least 90%, of the main surface of the composite pane. In particular, the low-refractive-index layer extends over the entire main surface of the composite pane. In a very advantageous embodiment of the invention, the low-refractive-index layer extends over the entire main surface of the composite pane, minus a frame-shaped peripheral edge region of the composite pane. Thus, in a plan view of the composite pane, the low-refractive-index layer is framed by an area that is not provided with the low-refractive-index layer. The coating-free edge region protects the low-refractive-index layer from moisture that could penetrate via the edge surface of the composite pane.

[0077] Preferably, the adhesive intermediate film extends over the entire main surface of the composite pane. However, it is also possible for the adhesive intermediate film to extend only over an area of ​​at least 80%, preferably at least 90%, of the main surface of the composite pane. In particular, the adhesive intermediate film extends over the entire main surface of the composite pane less a peripheral edge region of the composite pane. If the adhesive intermediate film does not extend over the entire main surface of the composite pane, those partial areas of the composite pane over which the adhesive intermediate film does not extend are preferably covered with a supplementary intermediate film, so that the adhesive intermediate film and the supplementary intermediate film, considered together, extend over the entire main surface of the composite pane. The supplementary intermediate film and the adhesive intermediate film preferably have overlap areas of less than 10 cm.2 , especially preferably less than 1 cm 2In particular, the supplementary intermediate film and the adhesive intermediate film do not overlap at all. This avoids partial thickness differences in the composite pane. The supplementary intermediate film can be made of the same material as the adhesive intermediate film or of a different material, preferably the same material. The supplementary intermediate film preferably has the same or greater thickness than the adhesive intermediate film. The low-refractive index layer is preferably not applied to the supplementary intermediate film. The use of an adhesive intermediate film framed by a supplementary intermediate film enables simplified application of the low-refractive index layer to the intermediate film, since this can be coated over the entire surface and is still sufficiently protected against moisture ingress into the composite pane via the edge surfaces.This enables coating processes such as magnetic field-assisted cathode sputtering (magnetron sputtering).

[0078] In a particularly preferred embodiment of the invention, the adhesive intermediate film extends over the entire main surface of the composite pane, minus a circumferential edge region of the composite pane. In addition, a further adhesive intermediate film is arranged substantially congruent with the adhesive intermediate film between the outer pane and the adhesive intermediate film. A supplementary intermediate film is arranged around the adhesive intermediate film and the further adhesive intermediate film. The supplementary intermediate film is therefore arranged like a frame around the adhesive intermediate film and the further adhesive intermediate film. The supplementary intermediate film and the adhesive intermediate film are therefore arranged such that the adhesive intermediate film and the supplementary intermediate film, viewed together, extend over the entire main surface of the composite pane.The additional intermediate film preferably has the same or greater thickness than the combined thickness of the framed bonding intermediate film and the framed additional intermediate film. The low-refractive-index layer is preferably applied to the outer surface of the bonding intermediate film. This optimally protects the low-refractive-index layer from damaging influences that may enter via the edge surfaces of the laminated pane.

[0079] In a further preferred embodiment, a middle pane is arranged between the adhesive intermediate film and the outer pane, with a thermoplastic intermediate layer, for example an adhesive intermediate film, being arranged between the outer pane and the middle pane. The composite pane thus comprises three panes, with adhesive intermediate layers arranged between the panes, which bond the inner pane to the middle pane and bond the middle pane to the outer pane.Preferably, the inner pane and the adhesive intermediate film arranged between the inner pane and the middle pane do not extend over the entire surface of the middle pane, so that the areal extent of the outer pane and the middle pane is each individually larger than that of the inner pane and the adhesive intermediate film and all other layers or elements arranged between the inner pane and the middle pane. This enables simplified coupling of light into the inner pane via the circumferential side edge surface of the inner pane. The middle pane can be made of the same materials as the inner pane and / or the outer pane or can be made of different materials. The thickness of the middle pane can vary widely.The middle pane preferably has a thickness in the range from 0.8 mm to 5 mm, more preferably from 1.4 mm to 2.5 mm, for example a standard thickness of 1.6 mm or 2.1 mm. Refractive indices are generally given in the context of the present invention based on a wavelength of 550 nm. Methods for determining refractive indices are known to those skilled in the art. The refractive indices given in the context of the invention can be determined, for example, by means of ellipsometry, wherein commercially available ellipsometers can be used. If the refractive index relates to a coating which has several layers in a layer stack, the specification of the refractive index means the effective refractive index across all layers. The effective refractive index describes the average optical density of a medium in which the light wave propagates / onto which it impinges.The effective refractive index takes into account the different refractive indices of the individual layers in the stack. Unless otherwise stated, the specification of layer thicknesses refers to the geometric thickness of a layer.

[0080] For those skilled in the art, it is clear what is meant by the stated layer thickness and how it can be measured. With regard to the adhesive intermediate film according to the invention, the stated layer thickness preferably means that it has a substantially constant thickness over its entire length, although customary error tolerances must be taken into account. The layer thickness can therefore deviate from the average layer thickness by + / - 5%, preferably + / - 3%, particularly preferably + / - 1%, depending on the location.

[0081] Methods for measuring the thickness of layers (both films and coatings) are known to those skilled in the art. The coatings can be determined using common methods for determining the thickness of thin films, for example, spectroscopic reflectometry, confocal microscopy, white light interferometry, or ellipsometry. These methods enable non-destructive measurement, and corresponding measuring instruments are commercially available. Ellipsometers are commercially available, for example, from Sentech. White light interferometry, profilometry, for example, confocal profilometry, or ellipsometry are preferred. For thicker layers in the micrometer range, such as the bonding intermediate film, the layer thickness can be determined using, for example, micrometer or light microscope methods.

[0082] The inner pane preferably has a light transmittance of at least 70%, particularly preferably at least 80%, very particularly preferably at least 90% (according to ISO 9050:2003). The adhesive intermediate film, if the low-refractive-index layer is applied to the outer surface, preferably has a light transmittance of at least 70%, particularly preferably at least 80%, very particularly preferably at least 90% (according to ISO 9050:2003). If further adhesive intermediate films are arranged between the inner pane and the low-refractive-index layer, these preferably have a light transmittance of at least 70%, particularly preferably at least 80%, very particularly preferably at least 90% (according to ISO 9050:2003).

[0083] "Transparent" in the sense of the invention means a light transmission (according to ISO 9050:2003) of at least 70%, preferably at least 80%, and particularly preferably at least 90%. "Semi-transparent" (according to ISO 9050:2003) in the sense of the invention means a light transmission of at most 70%, preferably at most 50%, and particularly preferably at most 30%. "Opaque" in the sense of the invention means a light transmission (according to ISO 9050:2003) of less than 30%, preferably less than 20%, particularly preferably less than 5%, and in particular less than 0.1%.

[0084] The composite pane preferably has an opaque masking region through which it is preferably not possible to see through. This masking region is preferably arranged circumferentially in an edge region of the composite pane and surrounds a central transparent see-through region in a frame-like manner. This is particularly common for vehicle windows. The masking region is formed in particular by an opaque element, for example by an opal masking print or an opaque section of the intermediate layer. The masking region is particularly preferably formed by an opaque masking print on the interior-side surface of the outer pane. Such a masking print is typically formed by an enamel containing glass frits and a black pigment, which is screen-printed and then fired into the surface.

[0085] The outer pane and the inner pane are preferably made of transparent glass, in particular soda-lime glass, which is common for window panes. In principle, however, the panes can also be made of other types of glass (e.g. borosilicate glass, quartz glass, aluminosilicate glass) or transparent plastics (e.g. polymethyl methacrylate or polycarbonate). The thickness of the outer pane and the inner pane can vary widely. Preferably, panes with a thickness in the range of 0.8 mm to 5 mm, more preferably 1.4 mm to 2.5 mm, for example those with the standard thicknesses of 1.6 mm or 2.1 mm, are used. The outer pane and the inner panes can be untempered, partially tempered, or tempered, independently of one another. If at least one of the panes is to be tempered, this can be thermal or chemical tempering. In an advantageous embodiment of the invention, the outer pane is tinted.This is particularly useful if the composite pane is used as a vehicle roof pane.

[0086] The outer pane, the inner pane, and the composite pane can have any three-dimensional shape. Preferably, the inner pane and the outer pane have no shadow zones, allowing them to be efficiently coated by cathode sputtering. The inner pane and the outer pane, and thus also the composite pane, are preferably flat or slightly or strongly curved in one or more directions of the room. The other pane is preferably curved in the same shape as the inner pane in the projection area.

[0087] In a further preferred embodiment of the invention, an optically controllable functional element is arranged between the low-refractive-index layer and the outer pane. The functional element is particularly preferably a PDLC functional element (polymer dispersed liquid crystal) with an active layer which is essentially responsible for the optical properties. The active layer of a PDLC functional element contains liquid crystals which are embedded in a polymer matrix. If no voltage is applied to the surface electrodes, the liquid crystals are aligned in a disordered manner, which leads to a strong scattering of the light passing through the active layer. If a voltage is applied to the surface electrodes, the liquid crystals in the second region of the active layer and optionally further regions of the active layer align themselves in a common direction and the transmission of light through the active layer is increased.Alternatively, functional elements, and in particular PDLC functional elements, can be used that are transparent when no voltage is applied (zero volts) and scatter strongly when a voltage is applied.

[0088] Alternatively, the optically controllable functional element can also be an electrochromic functional element or an SPD (suspended particle device). The controllable functional elements mentioned and their mode of operation are known to those skilled in the art, so a detailed description is unnecessary here.

[0089] In a particularly preferred embodiment, the functional element is a PDLC functional element and at least one adhesive intermediate film, preferably the adhesive intermediate film, is a plasticizer-free film. In particular, at least one of the plasticizer-free adhesive intermediate films is in direct spatial contact with the PDLC functional element. This is particularly advantageous because the active layer reacts very sensitively to plasticizers, which can, for example, diffuse from the intermediate layer into the active layer via the edge surfaces of the active layer. It is therefore advantageous to keep the concentration of plasticizers low or to avoid them in the immediate vicinity. The functional element can also be arranged more securely within the intermediate layer because the plasticizer-free film offers better stability when applying the layer stack.

[0090] In a further preferred embodiment of the invention, at least one further adhesive intermediate film is arranged between the adhesive intermediate film and the outer pane. Particularly preferably, two further adhesive intermediate films are arranged between the adhesive intermediate film and the outer pane, and a functional element, preferably a PDLC functional element, is arranged between these two adhesive intermediate films. In particular, a third further adhesive intermediate film is also arranged between the adhesive intermediate film and the outer pane, which is arranged circumferentially around the functional element. In other words, the functional element, or more precisely the side surfaces of the functional element, is circumferentially surrounded by the third further intermediate film. The third further intermediate film is designed like a frame with a recess into which the functional element is inserted.The third intermediate film arranged between the bonding intermediate film and the outer pane can be formed from a thermoplastic film into which the recess has been cut. Alternatively, the third intermediate film can also be composed of several film sections around the functional element.

[0091] The invention also extends to an illuminable glazing element comprising the composite pane according to the invention and a light source. The light source is arranged such that the light from the light source can be coupled at least partially, preferably mostly, into the inner pane.

[0092] In an advantageous embodiment, the light source is arranged in a masking region of the composite pane, and the light is coupled in within the masking region. As a result, the light source is not visible, at least to an observer from the external environment. The inner pane can be designed such that the light from the light source enters the inner pane via an edge surface of the inner pane. It is also possible for the light source to be arranged in a recess in the inner pane (for example in a feedthrough), so that the light is radiated into the inner pane via the side edge surface of the recess and is thereby coupled in. Methods for coupling light via the edge surface of light guides or via a recess are generally known to those skilled in the art and are disclosed, for example, in WO2010049638A1, US20120104789A1, and WO2018149568A1.

[0093] In a preferred embodiment, the inner pane has a light coupling means in the form of a reflective structure with a reflective surface, preferably a microprismatic structure. The reflective structure is preferably formed on the outer surface of the inner pane or attached to the outer surface of the inner pane. The reflective surface has a plurality of sections inclined towards the outer surface and is configured such that the light radiated into the inner pane and passing through the inner pane is reflected by the reflective surface and at least partially coupled back into the inner pane and optionally also into the bonding intermediate film and / or further intermediate films.The light from the light source is reflected by the reflective surface into the inner pane and coupled into it at an angle suitable for the coupled light to propagate at least partially (at least a portion of the coupled light) within the inner pane by total internal reflection at the interior surface and the interface with the low-refractive-index layer, so that the light reflects back and forth between the interior surface of the inner pane and the low-refractive-index layer. The light from the light source preferably enters the inner pane via the interior surface of the inner pane and then strikes the reflective structure so that it can be coupled into the inner pane. More precisely:

[0094] - the light from the light source passes through the inner pane, strikes the outer surface and is reflected there, if the reflective structure is formed in the outer surface; the reflective surface of the reflective structure is then a partial area of ​​the outer surface and the light is reflected by this partial area;

[0095] - Alternatively, the light from the light source passes through the inner pane, exits the inner pane again via the outer surface and is reflected by the reflective surface of the reflective structure if the reflective structure is attached to the outer surface; preferably, the light exiting the inner pane passes through the reflective structure and is reflected by its surface facing away from the inner pane, which forms the reflective surface.

[0096] In an alternative embodiment, the bonding intermediate film, which in this case has the low-refractive-index layer on the outer surface, or a further bonding intermediate film arranged between the inner pane and the bonding intermediate film, comprises a light coupling means in the form of a reflective structure with a reflective surface, preferably a microprismatic structure. The reflective structure is applied to the outer surface of the bonding intermediate film or the further bonding intermediate film.The reflective surface has a plurality of sections inclined towards the outer surface and is configured such that the light radiated into the bonding intermediate film and / or the further intermediate film and passed through the bonding intermediate film and / or the further intermediate film is reflected by the reflective surface and at least partially coupled into the bonding intermediate film and / or the further intermediate film and the inner pane. The light from the light source is reflected by the reflective surface at a coupling angle into the bonding intermediate film or the further intermediate film and coupled into it, which is suitable for the coupled light to propagate at least partially (at least a portion of the coupled light) in the inner pane and the bonding intermediate film and / or the further intermediate film by total internal reflection.The light from the light source preferably enters the laminated pane via the interior surface of the inner pane, transmits through the inner pane, exits at the exterior surface of the inner pane, enters the further adhesive intermediate film or the adhesive intermediate film via the interior surface of the further adhesive intermediate film or the adhesive intermediate film and then strikes the reflective structure so that it can be coupled into the inner pane.Alternatively, the light preferably enters the composite pane via the interior-side surface of the inner pane, is transmitted through the inner pane, exits on the exterior surface of the inner pane, enters the additional bonding intermediate film via the interior-side surface of the further bonding intermediate film, is transmitted through the additional bonding intermediate film, exits on the exterior surface of the further bonding intermediate film, enters on the exterior surface of the bonding intermediate film, and then strikes the reflective structure so that it can be coupled into the composite pane. The reflective surface is preferably provided with a reflective coating. The reflective coating comprises at least one reflective layer based on a metal or a metal alloy. This increases the reflectance of the reflective surface.

[0097] The reflective structure is preferably a microprism film. The microprism film is attached, for example glued, to the outer surface of the inner pane, the outer surface of the bonding intermediate film, or the outer surface of the further bonding intermediate film, preferably the outer surface of the inner pane. The reflective surface of the reflective structure is preferably arranged facing away from the inner pane. The microprism film is transparent. The light from the light source transmits through the microprism film and strikes its reflective surface, where it is reflected and passes through the microprism film again, entering the inner pane, the bonding intermediate film, or the further bonding intermediate film via the outer surface.

[0098] A microprism film is a flexible, particularly foil-like, polymeric film that has a smooth surface facing the inner pane and, in particular, is arranged on it, and a structured surface facing away from the inner pane. The structured surface is in the form of a planar arrangement of a plurality of prisms with dimensions in the micrometer range, wherein the prism surfaces form the inclined sections of the reflective surface. The microprisms act, in particular, as reflection prisms and reflect the light striking them in a direction that depends on the angle of inclination of the prism surfaces and the angle of incidence of the light. Microprism films are commercially available and can be purchased or specially produced during the manufacture of the glazing element or composite pane according to the invention.The edge length of the individual microprisms is preferably from 10 pm to 250 pm, particularly preferably from 20 pm to 100 pm, for example about 30 pm.

[0099] The microprism film can be multilayered. Commonly used microprism films include a substrate layer, for example, based on polyethylene terephthalate (PET), on which the microprisms are formed from a UV-curing polyacrylate. The microprism film is transparent and preferably has a light transmittance of at least 70%, particularly preferably at least 80%, and most particularly preferably at least 90% (according to ISO 9050:2003) relative to the light source. It is advantageous if the difference between the refractive indices of the inner pane or the adhesive intermediate film or the further adhesive intermediate film and the microprism film is as small as possible in order to reduce reflection losses at the interface between the corresponding film or pane and the microprism film.Preferably, said difference in refractive indices is at most 0.02 (relative to a wavelength of 550 nm), particularly preferably at most 0.01. If the inner pane or the bonding intermediate film or the further bonding intermediate film and the microprism film differ in refractive index, the microprism film preferably has a higher refractive index than the film or pane to which it is applied, which is advantageous for high-yield light coupling.

[0100] Instead of a flexible microprism film, a rigid microprism plate can also be used, i.e. a rigid plastic plate with a flat arrangement of microprisms.

[0101] The reflective structure can, however, also be formed directly in the outer surface of the inner pane, the outer surface of the adhesive intermediate film or the outer surface of the further adhesive intermediate film, preferably the outer surface of the inner pane. For this purpose, a portion of the outer surface is designed as a reflective surface. If the structure is formed in the inner pane, this is comparatively easy to achieve, particularly if the inner pane is a polymer layer, for example a plastic pane or plate. The light from the light source is reflected directly by the outer surface and then thrown back again. If the reflective surface with the reflective coating is only partially reflective, then of course some of the light escapes via the outer surface of the inner pane or plate.the bonding intermediate film or the further bonding intermediate film and is not reflected.

[0102] According to the invention, the reflective surface of the reflective structure has sections that are inclined relative to the interior-side surface of the inner pane. This means that the sections are not arranged parallel to the interior-side surface, but at an angle greater than 0° to the interior-side surface. Said sections have an angle to the interior-side surface that lies between 0° and 90°, preferably from 28° to 60° or from 30° to 60°, very particularly preferably from 30° to 50°, in particular from 40° to 50°, for example approximately 45°. This refers to the absolute value of the respective angle. The sections can be inclined in different directions.

[0103] The sections are preferably also inclined relative to each other. This means that adjacent sections are inclined relative to each other, i.e., they are not parallel, but rather arranged at an angle between 0° and 180°.

[0104] Said sections of the reflective surface are preferably substantially flat. The inclination of the sections of the reflective surface relative to the interior surface of the light guide determines the angle at which the reflected light is reflected back into the pane or film onto which the structure is applied or incorporated.

[0105] In a further preferred embodiment of the invention, a light coupling means is arranged, preferably applied, on the interior-side surface of the inner pane. The beam path of the light source is directed onto the light coupling means, so that light from the light source can be at least partially coupled into the inner pane and, if applicable, adjacent adhesive intermediate films. The light coupling means couples the light arriving from the light source into the inner pane and, if applicable, adjacent adhesive intermediate films, preferably by scattering, reflection, refraction, or diffraction. The light source is preferably connected to the inner pane via the light coupling means. A collimator can be arranged between the light source and the light coupling means, i.e., in the beam path of the light source.

[0106] The light coupling means arranged on the interior-side surface of the inner pane preferably has a light transmittance (according to ISO 9050:2003) of at least 20%, preferably at least 50%, in particular of at least 70%.

[0107] In an advantageous embodiment, the light coupling means is introduced into the interior-side surface of the inner pane, preferably by laser structuring, mechanical structuring such as sandblasting, and / or etching, preferably chemical or physical etching. A flat, irregular surface structuring that results in diffuse light scattering upon illumination is particularly suitable. Alternatively, linear or grid-shaped (e.g., cross-grid-shaped) structures can be introduced. Alternatively, the light coupling means is printed onto the interior-side surface of the inner pane, for example, by inkjet or screen printing. The print advantageously contains particles that are suitable for scattering, refracting, diffracting, or reflecting light.

[0108] In a further alternative advantageous embodiment, the light coupling means contains a transparent body which is materially connected to the interior-side surface of the inner pane, for example by gluing. The transparent body preferably contains or consists of a structured plastic film or plastic plate, for example with light-scattering, light-refracting, light-diffracting or light-reflecting particles. Alternatively, the transparent body preferably contains or consists of a holographic film. The transparent body can also contain or consist of a flat arrangement of microprisms, for example of randomly or grid-like arranged pyramids or of linearly arranged steps (hereinafter also referred to as step prisms). Typically, the transparent body has a surface structure made up of such microprisms.Such microprisms can advantageously be manufactured by mechanical processing such as stamping or embossing, by chemical etching, by photolithography or other transfer techniques.

[0109] The light propagates between the interior surface of the inner pane and the low-refractive-index layer until it hits either the side edge surface of the inner pane or, if bonded intermediate films are arranged between the low-refractive-index layer and the inner pane, the side edge surface of the bonded intermediate film or the side edge surface of the further bonded intermediate film, where it is coupled out. Alternatively, the light strikes a light-scattering element, which interrupts total internal reflection through light scattering, causing the light to be coupled out of the light guide via the respective element.

[0110] The glazing element is provided with a light source suitable for coupling light into the laminated pane. During operation, the light source emits visible light, i.e. electromagnetic radiation in the visible spectral range, in particular in the range from 380 nm to 780 nm. The light source can have one or more emission bands that are arranged in the visible spectral range and cover or cover part of it. However, the light source can also have a broad emission band that covers the entire visible spectral range. The emission band(s) - and thus the color of the emitted light - can be freely selected according to the requirements of the specific application.The glazing element can have a single light source or several separate light sources, the light of which is coupled into the inner pane, the adhesive intermediate film and / or the further adhesive intermediate film at different points.

[0111] Said light sources with different emission wavelengths preferably comprise a light source with a red emission color (in particular with a (average) emission wavelength of approximately 630 nm), a light source with a green emission color (in particular with a (average) emission wavelength of approximately 550 nm), and a light source with a blue emission color (in particular with a (average) emission wavelength of approximately 473 nm). The light from these light sources (RGB) superimposes to form white light, so that white light is coupled into the light guide and, if appropriate, the bonding intermediate film and / or the further bonding intermediate film.

[0112] The light source preferably comprises at least one light-emitting diode (LED). The light source can be a single light-emitting diode, but is preferably an array of multiple light-emitting diodes. Said array is preferably installed in a common housing, for example, as a linear array in which the light-emitting diodes are arranged along a line. The electroluminescent material of the light-emitting diode can be, for example, an inorganic semiconductor or an organic semiconductor. In the latter case, it is also referred to as an organic light-emitting diode (OLED).

[0113] Optionally, a collimator can be arranged between the light source and the reflective structure, wherein the collimator is located in the beam path of the light source. The collimator is preferably arranged between the light source and the interior surface of the light guide, in particular between the light source and the inner pane, so that the light is radiated into the composite pane or into the light guide via the collimator. The collimator generates a light beam from the typically divergent light beam of the light source, preferably with an essentially parallel beam path, or at least with a less divergent, i.e., more concentrated beam path. The beam cone of the light source is thus narrowed by the collimator.This has the advantage that the entire light beam is irradiated into the composite pane at the same angle of incidence, particularly at an angle of incidence that, in conjunction with the reflective properties of the reflective structure, ensures that a large portion of the light is coupled into the inner pane and, if applicable, the bonding intermediate film and / or the additional bonding intermediate film, resulting in total internal reflection. This optimizes the light output.

[0114] In the simplest case, the collimator is a type of converging lens, with the light source preferably positioned at its focal point. The collimator can be made, for example, from glass or a transparent plastic, in particular polycarbonate (PC) or polymethyl methacrylate (PMMA). The collimator is preferably attached, for example glued, to the interior surface of the inner pane. If the light source is designed as an arrangement of several light-emitting diodes, a separate collimator can be provided for each light-emitting diode. However, a common collimator is preferably used for the entire LED arrangement. In the case of a linear LED arrangement, for example, a rod-like collimator can be used whose length corresponds at least to the length of the LED arrangement.

[0115] The composite pane according to the invention can be produced by a process comprising the following process steps:

[0116] (A) providing a layer stack comprising the outer pane, the inner pane, the at least one adhesive intermediate film arranged in the layer stack between the inner pane and the outer pane, and the low-refractive-index layer applied to the adhesive intermediate film, and

[0117] (B) the lamination of the layer stack to form the composite pane.

[0118] The composite pane can be manufactured using conventional lamination processes, such as autoclave processes, vacuum bag processes, vacuum ring processes, calender processes, vacuum laminators, or combinations thereof. The bonding of the outer and inner panes is typically achieved using heat, vacuum, and / or pressure.

[0119] The composite pane according to the invention can be used as a window pane of a vehicle. A particularly preferred use is a vehicle roof pane, which is used to illuminate the vehicle interior. The vehicle can in principle be any land vehicle, watercraft, or aircraft, and is preferably a passenger car, truck, or rail vehicle. The composite pane can also be used in buildings, for example as a window pane, glass facade, or glass door, either indoors or outdoors, in particular as a window pane of a building or an interior. The composite pane can also be used as a component of furniture, electrical devices, as a component of furnishings, or as a furnishing.

[0120] The invention is explained in more detail with reference to drawings and embodiments. The drawings are schematic representations and not to scale. The drawings do not limit the invention in any way. They show:

[0121] Fig. 1 shows a cross-section through the composite pane according to Fig. 3,

[0122] Fig. 2 shows a cross-section through the illuminable glazing element according to Fig. 3,

[0123] Fig. 3 is a plan view of an embodiment of an illuminable glazing element according to the invention comprising an embodiment of the composite pane according to the invention,

[0124] Fig. 4-20 further embodiments of the composite pane according to the invention in a cross-sectional view and

[0125] Fig. 21-27 further embodiments of the illuminable glazing element according to the invention in a cross-sectional view.

[0126] Figure 1 shows a first embodiment of the composite pane 100 according to the invention in a cross-sectional view. Figure 2 shows a cross-sectional view of a first embodiment of the illuminable glazing element 101 according to the invention, which comprises the composite pane 100 from Figure 1. Figure 3 shows a plan view of the interior-side surface IV of the composite pane 100 from Figure 1 and a plan view of the illuminable glazing element 101 from Figure 2, wherein the cross section for the cross-sectional views in Figures 1 and 2 is indicated by a section line XX' in Figure 3.

[0127] The composite pane 100 is intended, for example, as a roof pane of a vehicle, in particular a passenger car. For the sake of simplicity, it is shown flat, although such vehicle roof panes are typically curved. The composite pane 100 is structurally formed from an outer pane 1, an inner pane 2, and an intermediate layer 3, via which the outer pane 1 and the inner pane 2 are connected to one another. The outer pane 1 and the inner pane 2 are made, for example, of soda-lime glass. The outer pane 1 has, for example, a thickness of 2.1 mm. The inner pane 2 has, for example, a thickness of 2.05 mm. The intermediate layer 3 comprises an adhesive intermediate film 3.1, which is formed, for example, from a PVB base with a thickness of, for example, 0.09 mm. The entire intermediate layer 3 with all intermediate films (no individual films are shown here) has, for example, a thickness of 0.76 mm.The inner pane 2 is clear, and the outer pane 1 and the bonded intermediate film 3.1 are each tinted to reduce the light transmission of the laminated pane 100 (for example, to less than 15%), as is common with vehicle roof windows. Alternatively, the bonded intermediate film 3.1 can also be untinted, i.e., clear.

[0128] The outer pane 1 has an interior-side surface II facing the intermediate layer 3 and an exterior-side surface I facing away from the intermediate layer 3. The inner pane 2 has an exterior surface III facing the intermediate layer 3 and an interior-side surface IV facing away from the intermediate layer 3. The adhesive intermediate film 3.1 has an interior-side surface ii facing the inner pane 2 and an exterior surface i facing the outer pane 1. The interior-side surfaces II, IV, ii face the vehicle interior when installed in a vehicle, whereas the exterior surfaces I, III, i face the external environment when installed in a vehicle.

[0129] A low-refractive-index layer 4 is applied to the interior-side surface ii of the adhesive intermediate film 3.1. The low-refractive-index layer 4 extends over the entire interior-side surface ii of the adhesive intermediate film 3.1. However, it is also possible for it to extend only over a partial area of ​​the interior-side surface ii of the adhesive intermediate film 3.1, for example the area of ​​the composite pane 100 which is intended for viewing (not shown here). The low-refractive-index layer 4 is therefore arranged directly adjacent to the inner pane 2. The low-refractive-index layer 4 has, for example, a refractive index of less than 1.4, whereas the inner pane 2 has a refractive index of 1.52. The low-refractive-index layer 4 consists, for example, of a polymeric matrix based on acrylic compounds, wherein hollow particles based on silicon dioxide are embedded in the polymer matrix.

[0130] The composite pane 100 has a circumferential, opaque edge region (masking region) along a circumferential side edge, in which a black masking print 6 is applied to the interior-side surface II of the outer pane 1, preventing visibility through the composite pane 100. The composite pane 100 has a total of four side edges, which together form the circumferential side edge of the composite pane 100. The composite pane 100 has two light-coupling means 7, wherein the two light-coupling means 7 are each arranged adjacent to one of two opposite side edges of the composite pane 100. Each of the light-coupling means 7 is, for example, a microprismatic film, which is applied to the outer surface III of the inner pane 2, for example, using a transparent adhesive.The light coupling means 7 are each arranged completely in front of the black cover print 6, so that the light coupling means 7 are not visible from an external environment when viewed through the composite pane 100. Preferably, a silver-based reflective layer is additionally applied to the microprismatic film of the light coupling means 7.

[0131] The glazing element 101 also has two light sources 9, which are, for example, light-emitting diodes (LEDs) (Figure 2 and Figure 3). The light sources 9 emit, for example, light 10 with a green emission color and an average emission wavelength of 550 nm. The light sources 9 are directed onto a partial area of ​​the interior-side surface IV of the inner pane 2. A collimator (not shown here) can optionally be arranged between each of the light sources 9 and the inner pane 2. The collimator is a transparent optical component, for example made of polycarbonate, which acts as a type of converging lens and reduces the beam cone of the light source 9, ideally to a parallel beam path. The collimator is, for example, glued to the interior-side surface IV of the inner pane 2, in particular via a layer of optically clear adhesive (not shown).The collimator is merely optional; it primarily improves the light output. The light sources 9 can be arranged alternatively to the collimator or additionally, for example, in a housing (not shown) that is attached to the interior-side surface IV of the inner pane 2.

[0132] In a plan view of the interior-side surface IV of the inner pane 2, each of the light sources 9 is arranged in front of a light coupling means 7. It is understood that both light sources 9 are not arranged in front of the same light coupling means 7. The two light sources 9 are thus arranged adjacent to opposite side edges of the composite pane 100.

[0133] The light 10 emitted by the light sources 9 via the interior surface IV passes through the inner pane 2 and strikes the exterior surface III of the inner pane 2. The light coupling means 7 is arranged there and is irradiated by the light 10. The light 10 incident on the light coupling means 7 is reflected at a specific angle, the coupling angle α. Due to the beveled surfaces of the microprismatic film coated with the silver layer, a large portion of the light 10 emitted by the light source 9 is reflected at the coupling angle α. A remaining portion of the light 10 is not reflected at the coupling angle α.

[0134] The coupling angle α describes the change in the direction of light propagation (represented by dashed arrows). The coupling angle α is the angle between the light vector incident on the microprismatic film (light coupling means 7) and the light vector emanating from the microprismatic film. The coupling angle α is between 90° and 180° and is, for example, approximately 102°.

[0135] The surfaces III, IV of the inner pane 2 each represent an interface to the adjacent low-refractive index layer 4 and the vehicle interior, respectively. At a wavelength of the light sources 9 of 550 nm, the refractive index of the inner pane 2 is 1.52 (soda-lime glass), the refractive index of the low-refractive index layer 4, for example, is 1.40 and the refractive index of air is approximately 1.00. From this, a critical angle of total reflection can be calculated for both surfaces III, IV: this is approximately 67° on the outer surface III (interface to the low-refractive index layer 4) and approximately 41° on the interior surface IV (interface to the air). The critical angle of total reflection is measured to the surface normal.

[0136] The light 10 from the light sources 9 is radiated into the inner pane 2 via the interior-side surface IV and, after transmission through the inner pane 2 and exiting via the exterior surface III, strikes the light coupling means 7. There, the light 10 is reflected. The light 10 then passes through the inner pane 2 and mostly strikes the interior-side surface IV of the inner pane 2 at an angle of incidence of >67° (also measured to the surface normal). Since the angle of incidence is greater than the critical angle of total internal reflection (41°), the light 10 is totally reflected, passes through the inner pane 2 again and strikes the exterior surface III at an angle of incidence of >67°. Here, too, the angle of incidence is greater than the critical angle of total internal reflection, so that the light 10 is again totally reflected.In this way, the light 10 is reflected back and forth between the surfaces III, IV, so to speak, so that it spreads within the inner pane 2 until it strikes the light-scattering elements 5 or the side edge surface of the inner pane 2 and is coupled out there. The low-refractive-index layer 4 lowers the critical angle, allowing more light 10 to be coupled into the inner pane 2. In the embodiment shown in Figure 3, the light 10 from the light sources 9 strikes the interior-side surface IV at an angle of incidence of 0° (measured with the surface normal) before being coupled in. However, it is also possible to radiate the light 10 not perpendicularly, but at an angle of incidence other than 0°. Alternatively, the light sources 9 can be arranged in a recess in the inner pane 2 or on a section of the circumferential edge surface of the inner pane 2 (not shown here).In these cases, the light 10 from the light sources 9 is coupled directly into the inner pane 2 via the edge surface (either the outer peripheral surface or that of the recess in the inner pane 2). In these cases, no additional light coupling means 7 is necessary.

[0137] Reference is now made to Figures 4 to 26, which all show various embodiments of the composite pane 100 according to the invention (Figures 4 to 20) or of the glazing element 101 according to the invention (Figures 21 to 26). All embodiments have in common that the composite pane 100 is, for example, a vehicle roof pane and an electronic functional element 8 is arranged between the outer pane 1 and the inner pane 2. The functional element 8 is, for example, a PDLC functional element; however, it can also be an SPD functional element or an electrochromic functional element. An adhesive intermediate film 3.4 is arranged between the outer pane 1 and the functional element 8, which is referred to below as the fourth adhesive intermediate film 3.4 in order to be able to better distinguish it from the other adhesive intermediate films 3.1, 3.2, 3.3, 3.5, in particular from the adhesive intermediate film 3.1 according to the invention. The fourth adhesive intermediate film 3.4 bonds the functional element 8 to the interior-side surface II of the outer pane 1. As described for Figures 1 to 3, the composite pane 100 of the embodiments of Figures 4 to 26 also has a circumferential, opaque edge region (masking region) along a circumferential side edge, in which a black masking print 6 is applied to the interior-side surface II of the outer pane 1, which prevents visibility through the composite pane 100.

[0138] In all embodiments of Figures 4 to 26, the functional element 8 does not extend over the entire surface of the composite pane 100, in particular, it does not extend over a peripheral edge region of the composite pane 100. However, the edge region of the functional element 8 is overlapped with the peripheral black cover print 6, so that the edge region of the functional element 8 is not visible from the outside. An adhesive intermediate film 3.3 extends in a frame-like manner around the edge surface of the functional element 8, which is referred to below as the third adhesive intermediate film 3.3 in order to be able to distinguish it more easily from the other adhesive intermediate films 3.1, 3.2, 3.4, 3.5, in particular from the adhesive intermediate film 3.1 according to the invention.

[0139] The functional element 8 has a thickness of 0.4 mm, for example. The fourth adhesive intermediate film 3.4 and the third adhesive intermediate film 3.3 each have, or together have, for example, a thickness of 0.38 mm to 0.4 mm and are formed, for example, based on PVB. The fourth adhesive intermediate film 3.4 is, for example, tinted to reduce the light transmission of the laminated pane 100 (for example, to less than 15%), as is common with vehicle roof windows; however, it can also be untinted, i.e., clear. Alternatively, the third adhesive intermediate film 3.3 has, for example, the same thickness as the functional element 8 to avoid local thickness differences in the laminated pane 100. The outer pane 1 has, for example, a thickness of 2.1 mm. The inner pane 2 has, for example, a thickness of 2.05 mm. The outer pane 1 and the inner pane 2 are made, for example, of soda-lime glass.The low-refractive-index layer 4 of all embodiments has, for example, a refractive index of less than 1.4, whereas the inner pane 2 has a refractive index of 1.52. The low-refractive-index layer 4 consists, for example, of a polymeric matrix based on acrylic compounds, wherein hollow particles based on silicon dioxide are embedded in the polymer matrix. Alternatively, the low-refractive-index layer 4 can also be based on porous silicon dioxide. All embodiments of Figures 4 to 20 also have in common that the light-coupling means 7 or the plurality of light-coupling means 7 is / are a microprismatic film, which can optionally be provided with a reflective layer, preferably based on silver.The light coupling means 7 are each arranged completely in front of the black cover print 6, so that the light coupling means 7 are not visible from an external environment when viewed through the composite pane 100. The light coupling means 7 are intended to be irradiated with visible light 10 by a light source 9, so that the light 10 can be coupled into the composite pane 100 by reflection at the light coupling means 7. The mode of operation of the (multiple) light coupling means 7 is similar to that described for Figures 1 to 3.

[0140] In Figure 4, the low-refractive-index layer 4 is arranged between the inner pane 2 and the adhesive intermediate film 3.1. The low-refractive-index layer 4 is applied to the interior-side surface ii of the adhesive intermediate film 3.1, for example, by means of a liquid printing process (inkjet) or, in the case of a mineral layer, by cathode sputtering. The composite pane 100 has two light-coupling means 7, wherein the two light-coupling means 7 are each arranged adjacent to one of the side edges of the composite pane 100 and the side edges lie opposite one another. In a plan view of the interior-side surface IV of the composite pane 100, the light-coupling means 7 are arranged completely in front of the cover print 6, such that the light-coupling means 7 cannot be seen from an external environment.The light coupling means 7 are connected, for example, by means of a transparent adhesive to the outer surface III of the inner pane 2. A second adhesive intermediate film 3.2 is arranged between the adhesive intermediate film 3.1 and the functional element 8. The adhesive intermediate film 3.1 is, for example, a PVB-based film, preferably a plasticizer-free PVB-based film, with a layer thickness of, for example, 0.1 mm. The second adhesive intermediate film 3.2 is, for example, based on PVB and has a thickness of 0.38 mm. The second adhesive intermediate film 3.2 is, for example, tinted. Because the adhesive intermediate film 3.1 is plasticizer-free, the low-refractive-index layer 4 can be applied to the intermediate film 3.1 with greater homogeneity. The intermediate layer 3 of the composite pane 100 is formed from all the adhesive intermediate films 3.1, 3.2, 3.3, 3.4, the low-refractive layer 4 and the functional element 8.

[0141] Light-diffusing elements 5 are applied to the outer surface III of the inner pane 2, for example, as a roughening of the glass surface. The light-diffusing elements 5 can alternatively also be applied as an imprint on the outer surface III of the inner pane 2. It is also possible for the light-diffusing elements 5 to be applied as an imprint on the surface of the low-refractive-index layer 4 facing the inner pane 2. If the low-refractive-index layer 4 is not applied to the interior-side surface ii of the adhesive intermediate film 3.1, the light-diffusing elements 5 can also be applied to the interior-side surface ii of the adhesive intermediate film 3.1. The low-refractive-index layer 4 extends over the entire surface of the composite pane 100, but can alternatively also extend only over a partial area of ​​the surface of the composite pane 100 (not shown here).

[0142] The variants shown in Figures 5 and 6 essentially correspond to the variant from Figure 4, so that only the differences are discussed here and otherwise reference is made to the description of Figure 4. In Figure 5, the low-refractive-index layer 4 is not applied to the interior-side surface ii of the adhesive intermediate film 3.1, but to the exterior-side surface i of the adhesive intermediate film 3.1.

[0143] In Figure 6, the bonding intermediate film 3.1 is arranged directly adjacent to the functional element s, and the second bonding intermediate film 3.2 is arranged between the inner pane 2 and the bonding intermediate film 3.1. In this embodiment, the bonding intermediate film 3.1 is preferably tinted, whereas the second bonding intermediate film 3.2 is preferably clear, i.e., not tinted. If light is coupled into the inner pane 2 via the light coupling means 7, it propagates for the most part not only within the inner pane 2, but also within the second bonding intermediate film 3.2. Due to the small difference in the refractive index between PVB and soda-lime glass, a large proportion of the light coupled into the inner pane 2 is not reflected at the interface between the inner pane 2 and the second bonding intermediate film 3.2; instead, the light is transmitted through the second bonding intermediate film 3.2 and is totally reflected at the interface between the second bonding intermediate film 3.2 and the low-refractive-index layer 4. The second bonding intermediate film 3.2 and the inner pane 2 thus essentially form a continuous light-conducting medium in which the light is reflected back and forth between the interface with the low-refractive-index layer 4 and the interface with the vehicle interior until it is decoupled. The second bonding intermediate film 3.2 can alternatively also be a plasticizer-free PVB-based film, preferably having a layer thickness of 0.05 mm.

[0144] The variant shown in Figure 7 essentially corresponds to the variant in Figure 6, so only the differences will be discussed here, and otherwise reference is made to the description of Figure 6 or the description of Figure 4. In Figure 7, the light-scattering elements 5 are applied, for example, as a print, to the surface of the second adhesive intermediate film 3.2 facing the functional element 8. Alternatively, the light-scattering elements 5 can also be applied to the surface of the low-refractive-index layer 4 facing the inner pane 2.

[0145] The variant shown in Figure 8 essentially corresponds to the variant from Figure 4, so that only the differences will be discussed here and otherwise reference is made to the description of Figure 4. In Figure 8, the light-scattering elements 5 are applied to the outer surface i of the adhesive intermediate film 3.1. The low-refractive-index layer 4 is also applied to the outer surface i of the adhesive intermediate film 3.1, although the light-scattering elements 5 are arranged between the adhesive intermediate film 3.1 and the low-refractive-index layer 4. The low-refractive-index layer 4 is therefore applied to the light-scattering elements 5 in some areas, but for the most part to the adhesive intermediate film 3.1.

[0146] The variant shown in Figure 9 essentially corresponds to the variant from Figure 6, so that only the differences will be discussed here and otherwise reference is made to the description of Figure 6 or the description of Figure 4. In Figure 9, the low-refractive index layer 4 is not applied to the interior-side surface ii of the adhesive intermediate film 3.1, but rather to the exterior-side surface i. In addition, a fifth adhesive intermediate film 3.5, for example based on PVB, is arranged between the adhesive intermediate film 3.1 and the functional element 8. The fifth adhesive intermediate film 3.5 is, for example, tinted. The light coupled into the inner pane 2 propagates not only in the inner pane 2, but also to a large extent via the adhesive intermediate film 3.1 and the second adhesive intermediate film 3.2. The adhesive intermediate film 3.1 is clear in this embodiment, i.e. not tinted.The second bonding intermediate film 3.2, for example, is a plasticizer-free film based on PVB.

[0147] The variants shown in Figures 10 to 12 essentially correspond to the variant from Figure 9, so that only the differences will be discussed here and otherwise reference is made to the description of Figure 9 or the description of Figures 4 and Figure 6. In Figures 10 and 11, the low-refractive-index layer 4 is applied to the interior-side surface ii of the adhesive intermediate film 3.1. In Figures 10 and 12, the light-scattering elements 5 are applied, for example, as a print on the surface facing the functional element 8 (outside surface) of the second adhesive intermediate film 3.2. In the case of the variant from Figure 12, the light-scattering elements 5 can alternatively also be applied to the interior-side surface ii of the adhesive intermediate film 3.1.In Figure 11, the light-scattering elements 5 are applied, for example, as an imprint on the surface of the second adhesive intermediate film 3.2 facing the inner pane 2 (interior-side surface). Alternatively, the light-scattering elements 5 can also be applied to the outer surface III of the inner pane 2 or to the low-refractive-index layer 4 (here, on the surface of the low-refractive-index layer 4 facing the inner pane 2).

[0148] The variant shown in Figure 13 essentially corresponds to the variant from Figure 6, so that only the differences will be discussed here and otherwise reference is made to the description of Figure 6 or the description of Figure 4. The composite pane 100 in Figure 13 also has a fifth adhesive intermediate film 3.5, which is arranged directly adjacent to the inner pane 2 and between the second adhesive intermediate film 3.2 and the inner pane 2. The second adhesive intermediate film 3.2 is arranged between the fifth 3.5 and the first adhesive intermediate film 3.1. The low-refractive index layer 4 is applied to the interior-side surface ii of the adhesive intermediate film 3.1. The light-scattering elements 5 are applied, for example, as a print on the surface of the second adhesive intermediate film 3.2 facing the inner pane 2 (i.e., the interior-side surface).Alternatively, they can also be applied to the surface of the fifth bonding intermediate film 3.5 facing the functional element 8 (outer surface). The bonding intermediate film 3.1 is, for example, based on PVB and has a layer thickness of 0.38 mm and is tinted. The second bonding intermediate film 3.2 and the fifth bonding intermediate film 3.5 are, for example, clear, i.e., untinted, and based on PVB. The fifth bonding intermediate film 5 is, for example, a plasticizer-free intermediate film.

[0149] The variants shown in Figures 14 to 16 essentially correspond to the variant from Figure 5, so that only the differences will be discussed here and otherwise reference is made to the description of Figure 5 or the description of Figure 4. In the variants of Figures 14 to 16, the adhesive intermediate film 3.1 does not extend over the entire surface of the composite pane 100. In a frame-shaped circumferential area of ​​the composite pane 100, a fifth adhesive intermediate film 3.5 is arranged, which surrounds the adhesive intermediate film 3.1 in a frame-shaped manner. In the variant of Figure 16, the fifth adhesive intermediate film 3.5 also surrounds the second adhesive intermediate film 3.2. In this variant (Figure 16), the second adhesive intermediate film 3.2 is arranged congruently with the adhesive intermediate film 3.1 in a plan view of the composite pane 100. The fifth adhesive intermediate film 3.In this case, 5 has a layer thickness that essentially corresponds to the combined layer thickness of the bonding intermediate film 3.1, the second bonding intermediate film 3.2, and the low-refractive-index layer 4. For the variants of Figures 14 and 15, the fifth bonding intermediate film 3.5 has a layer thickness that essentially corresponds to the thickness of the bonding intermediate film 3.1.

[0150] In Figures 14 and 16, the low-refractive-index layer 4 is applied to the outer surface i of the bonding intermediate film 3.1. In Figure 15, the low-refractive-index layer 4 is applied to the inner surface ii of the bonding intermediate film 3.1. In all three variants, the low-refractive-index layer 4 therefore does not extend over the entire surface of the composite pane 100. Furthermore, the variants of Figures 14 to 16 have only one light coupling means 7 in an edge region of the composite pane 100, although optionally more than one light coupling means 7 can also be arranged in the composite pane 100 (not shown here). With this variant, the bonding intermediate film 3.1 can be easily coated with the low-refractive-index layer 4 without having to mask partial areas during the coating process (e.g., magnetron sputtering).Because the edge area is free of the low-refractive-index layer 4, it is better protected from external influences.

[0151] The variants shown in Figure 17 and Figure 20 essentially correspond to the variant in Figure 5, so that only the differences are discussed here and otherwise reference is made to the description of Figure 5 or the description of Figure 4. In Figure

[0152] 17 and Figure 20, the low-refractive-index layer 4 extends only over a partial area of ​​the surface of the composite pane 100. A peripheral edge area of ​​the composite pane 100 is free of the low-refractive-index layer 4. In addition, the variants of Figures 17 and 20 have only one light coupling means 7 in an edge area of ​​the composite pane 100, although optionally more than one light coupling means 7 can also be arranged in the composite pane 100 (not shown here). In Figure 20, the light coupling means 7 is applied to the outer surface i of the adhesive intermediate film 3.1. The adhesive intermediate film 3.1 is particularly preferably a plasticizer-free film based on PVB with a layer thickness of, for example, 0.05 mm, but can alternatively also be a plasticizer-containing film based on PVB with a layer thickness of, for example, 0.38 mm.

[0153] The variants shown in Figure 18 and Figure 19 essentially correspond to the variant in Figure 6, so that only the differences are discussed here and otherwise reference is made to the description of Figure 6 or the description of Figure 4. In Figure

[0154] 18 and Figure 19, the low-refractive-index layer 4 extends only over a partial area of ​​the surface of the composite pane 100. A peripheral edge area of ​​the composite pane 100 is free of the low-refractive-index layer 4. In addition, the variants of Figures 18 and 19 have only one light coupling means 7 in an edge area of ​​the composite pane 100, although more than one light coupling means 7 can optionally be arranged in the composite pane 100 (not shown here). In Figure 18, the light coupling means 7 is applied to the surface facing the functional element 8 (outside surface) of the second adhesive intermediate film 3.2. In Figure 19, the light coupling means 7 is applied to the interior-side surface ii of the adhesive intermediate film 3.1. The second adhesive intermediate film 3.2 is particularly preferably a plasticizer-free film based on PVB with a layer thickness of, for example, 0.05 mm, but can alternatively also be a plasticizer-containing film based on PVB with a layer thickness of, for example, 0.38 mm.

[0155] Figures 21 to 27 show various variants of a glazing element 101 according to the invention. The various embodiments of the glazing element 101 of Figures 21 to 27 comprise, in addition to an inventive embodiment of the composite pane 100, a light source 9 which couples light 10 into the composite pane 100 or is arranged to couple light 10 into the composite pane 100. The light source 9 in all variants comprises, for example, a light-emitting diode (LED), which, for example, emits light 10 with a wavelength of 550 nm.

[0156] The variants of the composite pane 100 shown in Figures 21 and 22 essentially correspond to the variant from Figure 4, so that only the differences will be discussed here and otherwise reference is made to the description of Figure 4. In contrast to the composite pane 100 in Figure 4, the composite pane 100 here does not have a light coupling means 7. In the glazing element 101 of the variants, a light source 9 is arranged in a recess in the inner pane 2. The recess is, for example, a hole in the inner pane 2. The recess is arranged in front of the black cover print 6 when viewed through the composite pane 100 from the vehicle interior. The light source 9 is arranged such that the light 10 emitted by the light source 9 strikes the edge surface of the inner pane 2 located in the recess and is subsequently coupled into the inner pane 2 using the effect of total internal reflection.In the variant of Figure 21, the low-refractive-index layer 4 does not extend over the entire surface of the composite pane 100. In particular, the peripheral edge region of the composite pane 100 is free of the low-refractive-index layer 4. In the variant of Figure 20, the low-refractive-index layer 4 is arranged on the outside surface i of the adhesive intermediate film 3.1 instead of on the inside surface ii of the adhesive intermediate film 3.1.

[0157] The variant of the composite pane 100 shown in Figure 23 essentially corresponds to the variant from Figure 22, so that only the differences will be discussed here, and otherwise reference is made to the description of Figure 22 or to the description of Figure 4. In this embodiment, the inner pane 2 has no recess. Instead, the light source 9 is arranged in a circumferential edge region of the inner pane 2. The light source 9 is arranged such that the light emitted by the light source 9 strikes a region of the edge surface of the inner pane 2 and is subsequently coupled into the inner pane 2 using the effect of total internal reflection.

[0158] The variant of the composite pane 100 shown in Figure 24 essentially corresponds to the variant from Figure 21, so that only the differences will be discussed here and otherwise reference is made to the description of Figure 21 or to the description of Figure 4. In this embodiment, the inner pane 2 has no recess. Instead, the light source 9 is arranged in a circumferential edge region of the inner pane 2. The light source 9 is arranged such that the light 10 emitted by the light source 9 strikes a region of the edge surface of the inner pane 2 and is subsequently coupled into the inner pane 2 using the effect of total internal reflection.

[0159] The variants of the composite pane 100 shown in Figures 25 and 26 essentially correspond to the variant from Figure 21, so that only the differences will be discussed here, and otherwise reference is made to the description of Figure 21 or the description of Figure 4. In these embodiments, the inner pane 2 has no recess. Instead, the light source 9 is arranged in an edge region of the inner pane 2 on the interior-side surface IV. The light source 9 is directed at a light coupling means 7, which is also arranged on the interior-side surface IV of the inner pane 2. The light coupling means 7 is designed, for example, as a housing coated with a microprismatic film. The beam path of the light source 9 is, for example, parallel to the direction of extension of the inner pane 2.The light 10 from the light source 9 strikes the light coupling means 7 and is reflected by the microprismatic film such that it is coupled into the inner pane 2. In Figure 26, the low-refractive-index layer 4 is applied to the outer surface i of the bonding intermediate film 3.1 and extends over the entire surface of the composite pane 100, but can optionally also extend over only a partial area of ​​the surface of the composite pane 100.

[0160] The light coupling means 7 can optionally also be attached directly to the light source 9. It is also possible for the light coupling means 7 to be arranged between the inner pane 2 and the light source 9, wherein the radiation direction of the light source 9 in this case is preferably aligned substantially perpendicular to the interior-side surface IV of the inner pane 2 (not shown here). In such a case, the light 10 is deflected by the light coupling means 7 (for example, by light refraction) such that it is coupled into the inner pane 2.

[0161] Figure 27 shows a further embodiment of the glazing element 101 according to the invention. The composite pane 100 is designed, for example, as a vehicle roof pane. The composite pane 100 comprises an outer pane 1 and an inner pane 2, with a middle pane 11 arranged between the outer pane 1 and the inner pane 2. An adhesive intermediate film 3.1 and a second adhesive intermediate film 3.2 are arranged between the inner pane 2 and the middle pane 11. The adhesive intermediate film 3.1 is directly adjacent to the inner pane 2 and has a low-refractive-index layer 4 on the outside surface i, i.e., the surface facing away from the inner pane 2. However, the low-refractive-index layer 4 can alternatively also be applied to the interior-side surface ii of the adhesive intermediate film 3.1.A black masking print 6 is arranged in a peripheral edge area of ​​the outer pane 1 and the interior-side surface II of the outer pane 1, preventing visibility. All bonding intermediate films 3.1, 3.2, 3.3 are made, for example, from PVB without plasticizer. Alternatively, the intermediate films 3.1, 3.2, 3.3 can also be made from EVA, TPU, or polyacrylate compounds, preferably without plasticizer.

[0162] On the outer surface III of the inner pane 2, a plurality of light-scattering elements 5, for example as prints or roughened areas, are arranged or formed. A third adhesive intermediate film 3.3 is arranged between the outer pane 1 and the middle pane 11, which adhesive intermediate film 3.3 bonds the outer pane 1 and the middle pane 11 together. The inner pane 2, the adhesive intermediate film 3.1, and the second adhesive intermediate film 3.2 extend only over a partial area of ​​the surface of the outer pane 1, for example, only the see-through area of ​​the composite pane 100. A light source 9 is arranged in a section of the circumferential edge surface of the inner pane 2 and is arranged such that the light 10 emitted by it is coupled into the inner pane 2.

[0163] Optionally, the light sources 9 of all glazing elements 101 of Figures 2, 3 and 21 to 27 can also be equipped with a collimator. Reference numerals

[0164] 1 outer pane

[0165] 2 inner pane

[0166] 3 Intermediate layer

[0167] 3.1 adhesive intermediate film

[0168] 3.2 second adhesive intermediate film

[0169] 3.3 third adhesive intermediate film

[0170] 3.4 fourth adhesive intermediate film

[0171] 3.5 fifth adhesive intermediate film

[0172] 4 low-refractive layer

[0173] 5 light-scattering element

[0174] 6 black cover print

[0175] 7 Light coupling agents

[0176] 8 Functional element

[0177] 9 Light source

[0178] 10 Light from the light source 9

[0179] 11 middle slice

[0180] 100 composite panes

[0181] 101 Illuminated glazing element

[0182] I outside surface of the outer pane 1

[0183] II Interior surface of the outer pane 1

[0184] III outer surface of the inner pane 2

[0185] IV Interior surface of the inner pane 2 i Outside surface of the bonding intermediate film 3.1 ii Outside surface of the bonding intermediate film 3.1

Claims

Patent claims 1. A composite pane (100) for an illuminated glazing element (101), comprising: an outer pane (1), an inner pane (2) which has an outer surface (III) facing the outer pane (1) and an inner surface (IV) facing away from the outer pane (1), an adhesive intermediate film (3.1) which is arranged between the inner pane (2) and the outer pane (1) and has an outer surface (i) facing the outer pane (1) and an inner surface (ii) facing the inner pane (2), and a low-refractive-index layer (4) which is applied to one of the surfaces (i, ii) of the adhesive intermediate film (3.1), wherein the refractive index of the low-refractive-index layer (4) is at least 0.1 lower than the refractive index of the inner pane (2), wherein the adhesive intermediate film (3.1) has a layer thickness of 5 μm to 100 μm.

2. Composite pane (100) according to claim 1, wherein at least one light-scattering element (5) is arranged between the inner pane (2) and the low-refractive-index layer (4).

3. Composite pane (100) according to claim 1 or 2, wherein at least one light-scattering element (5) is applied to the interior-side surface (IV) and / or the exterior-side surface (III) of the inner pane (2), preferably only the exterior-side surface (III).

4. Composite pane (100) according to one of claims 1 to 3, wherein at least one further adhesive intermediate film (3.2) is arranged between the adhesive intermediate film (3.1) and the inner pane (2).

5. Composite pane (100) according to one of claims 1 to 4, wherein the adhesive intermediate film (3.1) has a plasticizer content of less than 5%, preferably less than 1% and is in particular free of plasticizers.

6. Composite pane (100) according to one of claims 1 to 5, wherein the adhesive intermediate film (3.1) has a layer thickness of 10 pm to 75 pm, preferably of 25 pm to 50 pm.

7. Composite pane (100) according to one of claims 1 to 6, wherein the adhesive intermediate film (3.1) is formed on the basis of polyvinyl butyral, ethylene-vinyl acetate copolymers, polyacrylate compounds or thermoplastic polyurethanes.

8. Composite pane (100) according to one of claims 1 to 7, wherein the low-refractive-index layer (4) is applied to the interior-side surface (ii) of the adhesive intermediate film (3.1).

9. Composite pane (100) according to claim 8, wherein exactly two further adhesive intermediate films (3.2, 3.3) are arranged between the adhesive intermediate film (3.1) and the inner pane (2).

10. Composite pane (100) according to one of claims 1 to 7, wherein the low-refractive-index layer (4) is applied to the outer surface (i) of the adhesive intermediate film (3.1).

11. Composite pane (100) according to one of claims 1 to 10, wherein the low-refractive-index layer (4) has a refractive index of at most 1.50, preferably at most 1.45, particularly preferably at most 1.

40.

12. Composite pane (100) according to one of claims 1 to 11, wherein the low-refractive-index layer (4) contains a polymer matrix of polyacrylate and particles based on silicon dioxide are embedded in the polymer matrix.

13. Composite pane (100) according to one of claims 1 to 12, wherein the low-refractive-index layer (4) extends over the entire surface of the composite pane (100) with the exception of a frame-shaped peripheral edge region.

14. Illuminable glazing element (101), comprising: - a composite pane (100) according to one of claims 1 to 13 and - a light source (9), wherein the light source (9) is arranged such that its light (10) can be at least partially coupled into the inner pane (2).

15. Glazing element (101) according to claim 14, wherein the inner pane (2) has a light coupling means (7) in the form of a reflective structure on the outer surface (III) or in the outer surface (III) and the light source (9) is arranged such that the light (10) is reflected at the light coupling means (7) and can thereby be coupled into the inner pane (2).

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