EP4330039A1

EP4330039A1 - Composite pane with functional film and busbar

Info

Publication number: EP4330039A1
Application number: EP22724446.4A
Authority: EP
Inventors: Arthur PALMANTIER; Uwe Van Der Meulen; Nino TINGS; Simon BREUER
Original assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Current assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Priority date: 2021-04-29
Filing date: 2022-04-21
Publication date: 2024-03-06
Also published as: CN115551706A; WO2022228985A1; US20240217215A1

Abstract

The invention relates to a composite pane (1) with a functional film (4), at least comprising a peripheral edge (K) of the composite pane (1), a peripheral edge (U) of the functional film (4), at least one busbar (5), an outer pane (2) with a surface (I) on the exterior side and a surface (II) on the interior side, an inner pane (6) with a surface (III) on the exterior side and a surface (IV) on the interior side, and a thermoplastic intermediate layer (3) which connects the surface (II) of the outer pane (2) on the interior side to the surface (III) of the inner pane (6) on the exterior side, wherein - the functional film (4) is encased in the thermoplastic intermediate layer (3), - the peripheral edge (U) of the functional film (4) is set back in the direction of the surface center of the composite pane (1) relative to the peripheral edge (K) of the composite pane (1), and - the at least one busbar (5) is arranged between the surface (II) of the outer pane (2) on the interior side and the surface (III) of the inner pane (6) on the exterior side and runs between the peripheral edge (K) of the composite pane (1) and the peripheral edge (U) of the functional film (4) in the edge region (R) of the composite pane (1), the distance x between the busbar (5) and the peripheral edge (U) of the functional film (4) equaling between 5 mm and 50 mm along the at least one busbar (5).

Description

Laminated pane with functional film and bus bar

The invention relates to a laminated pane comprising a functional film and at least one bus bar and a method for producing such a laminated pane.

Modern automotive glazing is increasingly being equipped with additional functions such as heatable layers, functional elements with electrically switchable optical properties, and displays. Often several of these elements are to be integrated within one glazing.

Windshields in particular are often equipped with so-called head-up displays (HUDs). Images are projected onto the windshield with a projector, typically in the area of the dashboard, where they are reflected and perceived by the driver as a virtual image (from his perspective) behind the windshield. In this way, important information can be projected into the driver's field of vision, for example the current driving speed, navigation or warning information, which the driver can perceive without having to take his eyes off the road. Head-up displays can thus make a significant contribution to increasing road safety.

DE 10 2014 220 189 A1 discloses a HUD projection arrangement which is operated with p-polarized radiation in order to generate a HUD image. Since the angle of incidence is typically close to the Brewster angle and p-polarized radiation is therefore reflected only to a small extent by the glass surfaces, the windshield has a reflective structure that can reflect p-polarized radiation in the direction of the driver. A single metallic layer with a thickness of 5 nm to 9 nm, for example made of silver or aluminum, is proposed as the reflecting structure, which is applied to the outside of the inner pane facing away from the interior of the car.

US 2004/0135742 A1 also discloses a HUD projection arrangement which is operated with p-polarized radiation in order to generate an HUD image and has a reflective structure which can reflect p-polarized radiation in the direction of the driver. The multilayer polymer layers disclosed in US Pat. No. 5,882,774 A are proposed as the reflective structure. DE 698 20 012 T2 discloses a method for laminating laminated panes comprising a polymeric intermediate layer with an infrared-reflecting coating, wherein layer portions of the polymeric intermediate layer which carry the infrared-reflecting coating are removed in the edge region of the laminated pane. This prevents corrosion of the coating from the edges of the pane.

Both head-up displays and other display applications or functional elements with electrically switchable optical properties are often used in the form of functional foils. This has the advantage that the functional film can be easily introduced into the stack of layers when laminating a laminated pane and can be prefabricated independently of the manufacture of the laminated pane. Functional films are usually based on one or more polymer carrier films on or between which functional layers are applied. During lamination, these polymer carrier films are bonded to the panes of the composite pane via thermoplastic composite films. Care must be taken to ensure that the layer stack is completely deaerated and that air pockets between the carrier foils and the composite foils are also completely removed. Remaining air pockets lead to product defects. If, in addition to the functional film to be integrated, other elements are attached that require a busbar for electrical contact, complete venting is made even more difficult. In addition to the problems described, more and more air pockets can be observed in the vicinity of the bus bar.

Accordingly, there is a need for composite panes comprising functional foils and busbars that do not have these disadvantages of the prior art. The object of the present invention is to provide such an improved laminated pane and a method for its production.

The object of the present invention is achieved according to the invention by a laminated pane according to claim 1 . Preferred embodiments emerge from the dependent claims.

The laminated pane according to the invention comprises an outer pane and an inner pane. The outer pane has an outside surface I and an inside surface II, while the inner pane has an outside surface III and an inside surface IV. The interior-side surface II of The outer pane is connected to the outside surface III of the inner pane via a thermoplastic intermediate layer. A functional film is embedded in the thermoplastic intermediate layer of the laminated pane. The composite pane includes a peripheral edge. The functional film also includes a peripheral edge, the peripheral edge of the functional film being set back from the peripheral edge of the laminated pane in the direction of the center of the surface of the laminated pane. The functional film is embedded in the thermoplastic intermediate layer. Furthermore, the laminated pane according to the invention comprises at least one busbar. The bus bar is integrated in the laminated pane between the inside surface II of the outer pane and the outside surface III of the inner pane. The busbar runs in the edge area of the laminated pane between the peripheral edge of the laminated pane and the peripheral edge of the functional film. According to the invention, the distance between the at least one bus bar and the peripheral edge of the functional film is between 5 mm and 50 mm, measured along the bus bar. The shortest distance between the bus bar and the peripheral edge of the functional foil is considered in each case.

The laminated pane according to the invention enables the combination of a functional film with a bus bar, which is arranged in the edge region of the laminated pane next to the functional film, without air inclusions and associated defects in the laminated pane occurring. The inventors have found that the distance according to the invention of 5 mm to 50 mm between the functional film and the busbar is essential for good lamination of the laminated pane. If the distance is too small, the air located between the peripheral edge of the functional film and the bus bar does not have sufficient opportunity to escape. If the distance is too large, the gap between the peripheral edge of the functional film and bus bar cannot be filled evenly by the material of the thermoplastic composite film that melts in the lamination process, and defects also occur. In the area according to the invention, on the other hand, error-free ventilation can be achieved.

The distance between the at least one bus bar and the peripheral edge of the functional film is preferably 10 mm to 30 mm, particularly preferably 15 mm to 25 mm, measured along the bus bar as the shortest distance in each case. A particularly uniform lamination can be observed within these areas. The laminated pane is intended to separate the interior from the outside environment in a window opening, in particular the window opening of a vehicle. In the context of the invention, the inner pane refers to the pane of the laminated pane facing the interior (in particular the vehicle interior). The outer pane refers to the pane facing the outside environment. The laminated pane is preferably a vehicle windshield (particularly the windshield of a motor vehicle, for example a car or truck). However, the composite pane can also be a side pane or a roof pane of a vehicle.

The laminated pane has an upper edge and a lower edge as well as two side edges running in between. The top edge designates that edge which is intended to point upwards in the installation position. The lower edge designates that edge which is intended to point downwards in the installation position. The upper edge is often referred to as the roof edge and the lower edge as the engine edge.

The outer pane and the inner pane each have an outside and an inside surface and a circumferential side edge running in between. Within the meaning of the invention, the outside surface designates that main surface which is intended to face the external environment in the installed position. Within the meaning of the invention, the interior-side surface designates that main surface which is intended to face the interior in the installed position. The interior surface of the outer pane and the outside surface of the inner pane face each other and are connected to one another by the thermoplastic intermediate layer.

The most varied of single-layer or multi-layer films known to those skilled in the art can be used as functional films. The invention is particularly suitable for integrating functional films with a carrier film material that itself exhibits poor adhesion to glass. Because of the low adhesion to glass, such carrier films are embedded between thermoplastic composite films, with bubble-free ventilation of such layer stacks being difficult, even in the absence of a bus bar in the edge area of the composite pane. The functional film preferably comprises at least one based on polyethylene terephthalate (PET), polyethylene (PE), polymethyl methacrylate (PMMA), triacetyl cellulose (TAC) and/or polycarbonate and/or copolymers or mixtures carrier film based thereon, particularly preferably a carrier film based on polyethylene terephthalate (PET). These materials are used as carrier foil material for commercially available functional foils and exhibit the ventilation problems described. In the presence of a bus bar in the edge area, venting is made even more difficult. The invention provides a remedy here.

Known functional foils that are used in the automotive sector are, for example, HUD foils, display foils and functional foils with electrically switchable optical properties. The functional films with electrically switchable optical properties include, for example, PDLC films, SPD films, electrochromic films or an electroluminescent film. These functional films with optical properties that can be switched electrically are generally designed as multilayer films comprising one or more carrier films and an active layer arranged thereon or in between. PET is usually used as the carrier film material. The active layer changes its optical properties when an electrical voltage is applied.

In one possible embodiment, the functional film is a PDLC (polymer dispersed liquid crystal) film. The active layer of a PDLC functional film contains liquid crystals embedded in a polymer matrix. The active layer is arranged between two carrier foils, surface electrodes being located on the surfaces of the carrier foils facing the active layer. If no voltage is applied to the surface electrodes, the liquid crystals are aligned in a disorderly manner, which leads to strong scattering of the light passing through the active layer. If a voltage is applied to the surface electrodes, the liquid crystals align in a common direction and the transmission of light through the active layer is increased. Such a PDLC functional film is known, for example, from DE 102008026339 A1.

In further possible configurations, the functional film is an SPD, an electrochromic or an electroluminescent functional film.

An SPD film (suspended particle device) contains an active layer comprising suspended particles, the absorption of light by the active layer being variable by applying a voltage to the surface electrodes. The change in absorption is based on the alignment of the rod-like particles in the electric field when the electrical voltage. SPD functional films are known, for example, from EP 0876608 B1 and WO 2011033313 A1.

In the case of an electrochromic functional film, the active layer of the functional film is an electrochemically active layer. The transmission of visible light depends on the degree of incorporation of ions in the active layer, with the ions being provided, for example, by an ion storage layer between the active layer and a surface electrode. The transmission can be influenced by the voltage applied to the surface electrodes, which causes the ions to migrate. Suitable functional layers contain, for example, at least tungsten oxide or vanadium oxide. Electrochromic functional elements are known, for example, from WO 2012007334 A1, US 20120026573 A1, WO 2010147494 A1 and EP 1862849 A1.

In the case of electroluminescent functional films, the active layer contains electroluminescent materials, in particular organic electroluminescent materials, the luminescence of which is excited by the application of a voltage. Electroluminescent functional films are known, for example, from US 2004227462 A1 and WO 2010112789 A2. The electroluminescent functional film can be used as a simple light source or as a display with which any representation can be shown.

Further functional films preferred within the scope of the invention are display films comprising a diffusely reflecting layer or surface which diffusely reflects incident light. Diffuse reflection is conceptually to be understood as non-directional reflection. On the diffusely reflecting layer, for example, an image from a projector directed from inside a vehicle onto the inner pane of the vehicle glazing is displayed, with the display film showing a real image in the plane of the laminated pane. A real image differs from a virtual image, the virtual image being in a different plane than the projection plane and the real image being shown in the projection plane.

For example, the display film includes a diffusely reflective internal surface with a diffusely reflective coating. The diffuse reflective coating preferably comprises nanoparticles or microparticles such as silicon dioxide particles, polymeric particles or liquid crystals. Alternatively, metal or metal oxide particles can also be used. In particular, the nanoparticles or microparticles mentioned have a spherical shape and/or are transparent or translucent. In particular, in particular Display foils with a diffusely reflective coating comprising titanium oxide particles (TiO _x particles) or silver particles have proven to be advantageous. In the same way, display foils with organic, diffusely reflecting coatings containing cholesteric liquid crystals are very well suited to ensuring good image quality. In a particularly preferred embodiment, the display film includes cholesteric liquid crystals that are oriented in a matrix. A possible example of a display film is described in WO 2017/204103 A1, the film comprising randomly dispersed cholesteric liquid crystal droplets covered by a refractive index-matched layer. The cholesteric liquid crystal droplets essentially have the shape of a hemisphere, the radius of which depends on the contact angle between the film and the droplet. A wavelength selectivity of the display film is also possible, as described for example in WO 2016/175183 A1.

If one surface of the display film comprises a random nanostructure or microstructure, another surface of the display film is preferably smooth.

In a further preferred embodiment, the display film includes a structured plastic film, which includes a number of structured surfaces and the properties of the display film are determined by the incline of the contact surfaces between adjacent structured layers. Exemplary embodiments and methods for structuring the layers of the display film are described in WO 2012/104547 A1. Compared to particle-based display foils, structured display foils often achieve less haze and a better luminance factor (also known as "screen gain").

The display film preferably comprises a film containing polyethylene (PE), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), triacetyl cellulose (TAC) and/or polycarbonate as the carrier material.

Suitable display films are in principle commercially available, with triacetyl cellulose, polymethyl methacrylate or polycarbonate being used as common carrier materials. These materials show only very little adhesion to glass panes and for this reason are embedded between thermoplastic composite films, with the bubble-free ventilation of such layer stacks being difficult, even in the absence of a busbar in the edge region of the composite pane. The functional film is particularly preferably a reflective film that can be replaced as a HUD film. The reflective foil is metal-free and suitable for reflecting at least 5%, preferably 10% to 50%, particularly preferably 15% to 30%, in particular 20% to 25% of p-polarized light incident on the foil. This is particularly advantageous in terms of a good HUD image.

The reflective foil preferably has a thickness between 20 μm (microns) and 120 μm, particularly preferably between 30 μm and 90 μm, very particularly preferably between 50 μm and 75 μm.

The reflective film is preferably a film based on polyethylene terephthalate (PET), which is coated with a stack of copolymer layers based on PET and/or polyethylene naphthalate (PEN). The coating is preferably applied to the interior surface, i.e. the surface facing the vehicle interior. Suitable reflective films are described in US Pat. No. 5,882,774 A, for example.

Particularly in the case of the reflective foils described as HUD foils or the diffusely reflective display foils, there is a great need to integrate these functions into a composite pane at the same time as elements that require a voltage supply. Here, for example, heatable laminated panes should be mentioned, which at the same time have a HUD film or a diffusely reflecting display film.

The at least one busbar of the laminated pane according to the invention enables the voltage supply of an electrical element in the laminated pane, the distance of the busbar to the functional film according to the invention making it possible to combine the electrical element with the functional film in the first place.

The laminated pane preferably comprises at least two busbars. The busbars are preferably attached to two opposite sections of the peripheral edge of the laminated pane. In this way, voltage can be applied to opposite portions of an electrical element.

The at least one busbar is preferably mounted on an electrically conductive layer and is electrically conductively contacted with it. Particularly preferred are at least two busbars are electrically conductively contacted on the electrically conductive layer, with both busbars being arranged in the edge area of the laminated pane at a distance of 5 mm to 50 mm from the peripheral edge of the functional film. The shortest distance between the bus bar and the nearest edge of the functional film is considered.

The electrically conductive layer can be introduced into the laminated pane by means of various technologies known to those skilled in the art. The electrically conductive layer is preferably applied to a carrier film or directly to a pane of the laminated pane.

The electrically conductive layer is preferably applied flat to the interior surface of the outer pane or the outside surface of the inner pane. The electrically conductive layer is preferably a heating layer. The electrically conductive layer has at least two busbars, which are preferably arranged on opposite sections of the peripheral edge of the laminated pane. When an electrical voltage is applied between the at least two busbars, electrical current flows through the electrically conductive layer and is heated in the process.

If the functional film according to the invention is a reflective film in the form of an HUD film or a diffusely reflective display film, then the electrically conductive layer is preferably arranged on the surface of the outer pane on the interior side. This has the advantage that the electrically conductive layer does not affect the image projected onto the functional film.

Glazings with electrically conductive layers are known to those skilled in the art. In principle, any electrically conductive layers that can be electrically conductively contacted by a busbar can be used in connection with the invention.

The electrically conductive layer contains at least one metal, a metal alloy or a transparent conductive oxide, preferably a transparent conductive oxide, and has a thickness of 10 nm to 2 μm. The electrically conductive layer is preferably transparent. Here, transparent means permeable to electromagnetic radiation, preferably electromagnetic radiation with a wavelength of 300 nm to 1,300 nm and in particular to visible light. Suitable electrically conductive layers are, for example, from WO03/024155, US2007/0082219A1, US2007/0020465A1, WO2013/104438 or WO2013/104439, DE 202008 017611 U1, EP 0 847 965 B1 or WO2012/052315 A1. They typically contain one or more, for example two, three or four, electrically conductive, functional individual layers. The functional individual layers preferably contain at least one metal, for example silver, gold, copper, nickel and/or chromium, or a metal alloy. The functional individual layers particularly preferably contain at least 90% by weight of the metal, in particular at least 99.9% by weight of the metal. The functional individual layers can consist of the metal or the metal alloy. The functional individual layers particularly preferably contain silver or a silver-containing alloy. Such functional individual layers have a particularly advantageous electrical conductivity combined with high transmission in the visible spectral range. The thickness of a functional individual layer is preferably from 5 nm to 50 nm, particularly preferably from 8 nm to 25 nm. In this thickness range, an advantageously high transmission in the visible spectral range and a particularly advantageous electrical conductivity are achieved.

The busbars include an electrically conductive structure, preferably containing silver, and have a thickness of 5 μm to 40 μm, for example. The width of the bus bars is preferably 0.5 mm to 30 mm, particularly preferably 1 mm to 20 mm. The busbars are preferably attached at a distance of 0.5 mm to 20 cm from the nearest section of the peripheral edge of the laminated pane.

The busbars are intended to be connected to an external voltage source, with current flowing across the electrically conductive layer as a result of an electrical potential difference.

The attachment of the bus bars can be done in particular by laying, printing, soldering or gluing.

In a preferred embodiment, the busbars are in the form of a printed and burned-in conductive structure. The printed bus bars contain at least one metal, preferably silver. The electrical conductivity is preferably realized via metal particles contained in the busbar, particularly preferably via silver particles. The metal particles can be in an organic and/or inorganic matrix such as pastes or inks, preferably as a fired screen printing paste with glass frits. The layer thickness of the printed busbar is preferably from 5 μm to 40 μm, more preferably from 8 pm to 20 pm and most preferably from 10 pm to 15 pm. Printed busbars with these thicknesses are technically easy to implement and have an advantageous current-carrying capacity.

In a further preferred embodiment, the busbars are designed as strips of an electrically conductive foil. The busbars then contain, for example, at least aluminum, copper, tinned copper, gold, silver, zinc, tungsten and/or tin or alloys thereof. The strip preferably has a thickness of 10 μm to 500 μm, particularly preferably 30 μm to 300 μm. Busbars made of electrically conductive foils with these thicknesses are technically easy to implement and have an advantageous current-carrying capacity. The strip can be electrically conductively connected to the electrically conductive layer, for example via a soldering compound, via an electrically conductive adhesive or an electrically conductive adhesive tape, or by direct application. To improve the conductive connection, a silver-containing paste, for example, can be arranged between the electrically conductive layer and the busbar.

The thermoplastic intermediate layer preferably comprises at least a first thermoplastic composite film and a second thermoplastic composite film, between which the functional film is inserted. The first thermoplastic composite film and the second thermoplastic composite film are arranged above and below the functional film and enclose the functional film. The first thermoplastic composite film connects the functional film to the outer pane and the second composite film connects the functional film to the inner pane.

The first thermoplastic composite film and the second thermoplastic composite film can, independently of one another, contain at least polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), polyurethane (PU) or mixtures or copolymers or derivatives thereof, preferably polyvinyl butyral (PVB).

The first thermoplastic composite film and the second thermoplastic composite film can be formed independently of one another by a single film or by more than one film.

The first thermoplastic composite film and the second thermoplastic composite film can be between 20 pm (microns) and 2 mm thick. The first thermoplastic The thickness of the composite film and/or the second thermoplastic composite film can be, for example, between 0.2 mm and 2 mm, particularly preferably from 0.3 mm to 1 mm, for example 0.38 mm or 0.76 mm. The thickness of the first thermoplastic composite film and the thickness of the second thermoplastic composite film is preferably constant over the entire length, so the intermediate layers have a rectangular cross section. The composite films are therefore not wedge films. If the first thermoplastic composite film or the second thermoplastic composite film is a functional composite film with acoustically damping properties, it is preferably 0.51 mm or 0.84 mm thick.

In a particularly preferred embodiment, the functional film is a reflective film as a HUD film or a diffusely reflecting display film, the first thermoplastic composite film having a thickness of 200 μm to 1000 μm, preferably 300 μm to 850 μm, and the second thermoplastic composite film between 10 μm and 120 μm, preferably between 15 μm and 90 μm, particularly preferably between 20 μm and 75 μm thick. When using the laminated pane as a head-up display or diffuse display of a motor vehicle, a projector is generally attached in the area of the dashboard and an image is projected onto the interior surface of the inner pane. The second thermoplastic composite film is in the beam path between the projector and the functional film. If the second thermoplastic composite film is made as thin as possible, this is advantageous with regard to the image quality of the projected image.

Optionally, the first thermoplastic composite film or the second thermoplastic composite film or both the first thermoplastic composite film and the second thermoplastic composite film is a functional intermediate layer. A “functional intermediate layer” is a composite film that has at least one special function, in particular an acoustic function, a color function, a solar function or a combination of these functions.

In one embodiment only the first thermoplastic composite film or only the second thermoplastic composite film is a functional intermediate layer. However, it is also possible for both the first thermoplastic composite film and the second thermoplastic composite film to be functional intermediate layers, in which case they can have the same or preferably different functions. In a particularly preferred embodiment, the first thermoplastic composite film and/or the second thermoplastic composite film is a functional intermediate layer with acoustically damping properties. Such an acoustically damping composite film typically consists of at least three layers, with the middle layer having a higher plasticity or elasticity than the outer layers surrounding it, for example as a result of a higher proportion of plasticizers.

It has proven particularly advantageous if the first thermoplastic composite film, which connects the functional film to the outer pane, is designed as an acoustically damping composite film. This results in advantageous acoustic properties of the laminated pane.

Acoustically damping composite films are generally characterized by what is known as a mechanical impedance measurement (MIM, mechanical impedance measurement). This is a standardized procedure that can be found in ISO 16940, from which the damping can be calculated by measuring the natural frequencies. According to the standard, the acoustically damping composite film to be examined is laminated between two glass panes with a thickness of 2.1 mm in order to enable a corresponding comparison with different glass thicknesses. The person skilled in the art is thus able to select suitable intermediate layers using a well-known standardized measurement method.

The mechanical impedance measurement is carried out at the earliest one month after the production of the laminated glass. Furthermore, the acoustically damping composite film itself is laminated to form a composite glass with the two glass panes of 2.1 mm thickness at the earliest one month after its production. This ensures that a stable state has developed at the time of the measurement.

In a preferred embodiment of the invention, an acoustically damping composite film is used as the first composite film, in which the damping factor hi of the first mode and the damping factor r\2 of the second mode of a laminated glass pane with a surface of 25 mm x 300 mm consisting of two Glass panes with a thickness of 2.1 mm each, between which the acoustically damping composite film is laminated, with a mechanical impedance measurement (MIM) according to ISO 16940 at a temperature of 20°C hi > 0.20 and r\2 > 0.25 , preferably hi > 0.25 and r 2 > 0.30, particularly preferably hi > 0.25 and r 2 ≈ 0.35. The functional film preferably extends over at least 80% of the pane surface. In particular, the functional film is arranged over the entire surface between the first thermoplastic intermediate layer and the second thermoplastic intermediate layer, with the exception of a peripheral edge region which, as a communication window, is intended to ensure the transmission of electromagnetic radiation through the laminated pane, so that no functional film is preferably arranged there. In areas where busbars are provided, the distances between the functional film and busbar are designed according to the invention. In the remaining areas along the peripheral edge of the laminated pane, the functional film is preferably removed in a peripheral edge area. The peripheral edge area, in which preferably no functional film is arranged, has a width of up to 20 cm, for example, in particular a width of 20 mm. It also prevents the functional film from coming into direct contact with the surrounding atmosphere, so that the functional film inside the laminated pane is protected against corrosion and damage.

In one embodiment, the functional film extends over the entire pane surface with the exception of areas of the busbars in which the distances according to the invention apply.

The laminated pane according to the invention can additionally include a cover print, in particular made of a dark, preferably black, enamel. The masking print is in particular a peripheral, ie frame-like, masking print. The peripheral masking print primarily serves as UV protection for the assembly adhesive of the laminated pane. The cover print can be opaque and full-surface. The cover print can also be semi-transparent, at least in sections, for example as a dot grid, stripe grid or checkered grid. Alternatively, the covering print can also have a gradient, for example from an opaque covering to a semi-transparent covering. In a preferred embodiment, the covering print is designed in such a way that the side edges of the reflective film are covered by it when the laminated pane is viewed from above. If the composite pane has communication, sensor or camera windows, the masking print is preferably enlarged around the communication, sensor or camera windows in the direction of the center of the pane, so that the cut edges of the recess(es) also around the communication, sensor or Camera windows are covered by the masking print. The masking print is usually applied to the interior surface of the outer pane or to the interior surface of the inner pane.

The peripheral edge of the functional film is preferably covered by the opaque covering print of the laminated pane. Since the collector conductors of the composite pane lie between the peripheral edge of the functional film and the peripheral edge of the composite pane, these are also covered by the masking print. This leads to a visually appealing lamination of the bus bars and the edge of the functional film.

The outer pane and/or the inner pane can have anti-reflection coatings, non-stick coatings, anti-scratch coatings, photocatalytic coatings, sun protection coatings and/or low-E coatings.

The outer pane and the inner pane are preferably made of glass, in particular of soda-lime glass, which is common for window panes. In principle, however, the panes can also be made of other types of glass (for example borosilicate glass, quartz glass, aluminosilicate glass) or transparent plastics (for example polymethyl methacrylate or polycarbonate). The thickness of the outer pane and the inner pane can vary widely. Disks with a thickness in the range from 0.8 mm to 5 mm, preferably from 1.4 mm to 2.5 mm, are preferably used, for example those with the standard thicknesses of 1.6 mm or 2.1 mm. However, it is also possible for the outer pane and/or the inner pane to have a thickness of 0.55 mm or 0.7 mm.

The outer pane and the inner pane can be clear and colorless, but also tinted or tinted, independently of one another. In a preferred embodiment, the total transmission through the laminated glass is greater than 70%. The term total transmission refers to the procedure specified by ECE-R 43, Appendix 3, Section 9.1 for testing the light transmittance of motor vehicle windows.

The outer pane and the inner panes can be unprestressed, partially prestressed or prestressed independently of one another. If at least one of the panes is to have a prestress, this can be a thermal or chemical prestress. The laminated pane according to the invention is preferably curved in one or more spatial directions, as is customary for motor vehicle panes, with typical radii of curvature being in the range from about 10 cm to about 40 m. However, the composite pane according to the invention can also be flat, for example if it is intended as a pane for buses, trains or tractors.

In one possible embodiment, the first thermoplastic composite film and/or the second thermoplastic composite film is a functional intermediate layer with a color function. This means the intermediate layer is colored or tinted. The intermediate layer can be tinted or colored over its entire surface. Alternatively, the intermediate layer can also have a color gradient or a colored pattern. In the case of laminated panes that are intended as windshields, the coloring or tinting is designed in such a way that the laminated pane has a light transmission of more than 70% in the spectral range from 380 nm to 780 nm. In the case of composite panes that are intended as roof panes or rear side windows, the coloring or tinting can also be darker and the composite panes can thus have a light transmission of 70% or less in the spectral range from 380 nm to 780 nm.

The first thermoplastic composite film and/or the second thermoplastic composite film can also be a functional intermediate layer in which two or more functional properties are combined, for example acoustically damping properties with a color function and/or a solar function.

A particularly preferred configuration of the laminated pane according to the invention preferably comprises a functional film which is a reflective film as an HUD film or a diffusely reflective display film, preferably a reflective film as an HUD film. The laminated pane has at least two busbars which contact the electrically conductive layer in an electrically conductive manner and which are each attached along the peripheral edge of the laminated pane at the distances from the functional film according to the invention. The electrically conductive layer is applied to the surface of the outer pane on the interior side and is preferably provided as a heating layer. The busbars are positioned along opposite portions of the peripheral edge of the laminated pane.

Such a preferred embodiment of the composite pane according to the invention with a functional film as a HUD film can be equipped with a projector, with a Projection arrangement for a head-up display (HUD) is obtained. Such a projection arrangement is primarily used in motor vehicles, with the composite pane preferably being a windshield. As is usual with HUDs, the projector illuminates an area of the windshield where the radiation is reflected in the direction of the viewer (driver), creating a virtual image which the viewer perceives from behind the windshield as seen from his/her perspective. The area of the windscreen that can be irradiated by the projector is referred to as the HUD area. The beam direction of the projector can typically be varied using mirrors, particularly vertically, in order to adapt the projection to the viewer's height. The area in which the viewer's eyes must be located for a given mirror position is referred to as the eyebox window. This eyebox window can be shifted vertically by adjusting the mirrors, with the entire area accessible in this way (that is to say the superimposition of all possible eyebox windows) being referred to as the eyebox. A viewer located within the eyebox can perceive the virtual image. Of course, this means that the viewer's eyes must be inside the eyebox, not the entire body.

The technical terms used from the field of HUDs are generally known to the person skilled in the art. For a detailed description, reference is made to the dissertation "Simulation-based measurement technology for testing head-up displays" by Alexander Neumann at the Institute for Computer Science of the Technical University of Munich (Munich: University Library of the Technical University of Munich, 2012), in particular to Chapter 2 "The Head- up display".

The proportion of p-polarized radiation in the total radiation from the projector is preferably at least 70%. In an advantageous embodiment of a

Projection arrangement for a head-up display, the proportion of p-polarized radiation in the total radiation of the projector is at least 80%, the proportion of p-polarized radiation in the total radiation of the projector is particularly preferably 80% or 100%, very particularly preferably 100 %.

The specification of the direction of polarization refers to the plane of incidence of the radiation on the laminated pane. P-polarized radiation is radiation whose electric field oscillates in the plane of incidence. S-polarized radiation is radiation whose electric field oscillates perpendicular to the plane of incidence. the The plane of incidence is spanned by the incidence vector and the surface normal of the composite pane in the geometric center of the HUD area.

The radiation from the projector preferably strikes the laminated pane at an angle of incidence of 50° to 80°, in particular 60° to 70°, typically around 65°, as is usual with HUD projection arrangements. The angle of incidence is the angle between the incidence vector of the projector radiation and the surface normal at the geometric center of the HUD area. Since the angle of incidence of around 65°, which is typical for HUD projection arrangements, is relatively close to the Brewster angle for an air-glass transition (57.2°, soda-lime glass), the p-polarized radiation components of the radiation emitted by the projector are emitted by the pane surfaces hardly reflected. However, the reflective foil contained in the laminated pane is optimized for the reflection of p-polarized radiation. In this way, the image perceived by the viewer is not, or only to a very small extent, distorted by a ghost image. A wedge-shaped intermediate layer can thus be dispensed with.

In one embodiment of the projection arrangement, 10% to 50%, preferably 15% to 30%, particularly preferably 20% to 25% of the p-polarized light emitted by the projector and impinging on the reflective film of the composite pane are directed by the reflective film in the direction of the viewer reflects.

The invention also relates to a method for producing a laminated pane according to the invention, at least comprising the steps of a) providing an inner pane or an outer pane, b) attaching at least one busbar, c) applying a thermoplastic intermediate layer with a functional film and d) placing an outer pane or inner pane to finish of the layer stack and laminating to form a composite pane, the functional film being cut back before or during step c) and the peripheral edge of the functional film being at a distance of 5 mm to 50 mm from the at least one bus bar after cutting back.

Before or during step a), an electrically conductive layer is preferably applied to the inside surface of the outer pane or the outside surface of the inner pane and the at least one bus bar to the electrically conductive one Layer applied electrically conductive. The electrically conductive layer is applied using methods known to those skilled in the art. The electrically conductive layer is preferably applied to a pane surface by physical vapor deposition (PVD), particularly preferably by cathode sputtering (“sputtering”), very particularly preferably by magnetic field-assisted cathode sputtering (“magnetron sputtering”). The electrically conductive layer is applied before the laminated pane is laminated. Instead of applying the coating to a pane surface, it can in principle also be provided on a carrier film.

The thermoplastic intermediate layer with the functional film is applied in one or more steps in step c). The thermoplastic intermediate layer preferably comprises at least a first thermoplastic composite film and a second thermoplastic composite film, between which the functional film is inserted. The functional film can be inserted between the thermoplastic composite films before the intermediate layer is placed in step c). In this case, the thermoplastic intermediate layer with the functional film is applied as a trilayer in one step. Optionally, the thermoplastic composite films and the functional film can also be applied individually in step c), the intermediate layer with the embedded functional film being produced directly in step c).

The functional film can be cut back before or during step c) using methods customary in the art, such as laser cutting methods or also cutting to size using a knife blade.

A ventilation structure is preferably stamped into the at least one busbar during or after step b) and before step d). The venting structure further facilitates venting of the layer stack. The ventilation structure can be introduced into the at least one bus bar, for example, by means of a structured roller, a toothed rolling tool or similar tools.

The laminated pane according to the invention can be laminated in step d) by methods known per se. The outer pane, the inner pane and the functional film lying in between are laminated to one another via the thermoplastic composite films, for example by autoclave methods, vacuum bag methods, vacuum ring methods, calendering methods, vacuum laminators or combinations thereof. The connection of The outer pane and the inner pane usually take place under the action of heat, vacuum and/or pressure.

If the composite pane is to be curved, the outer pane and the inner pane are preferably subjected to a bending process before lamination. The outer pane and the inner pane are preferably bent congruently together (i.e. at the same time and using the same tool), because the shape of the panes is then optimally matched to one another for the lamination that takes place later. Typical temperatures for glass bending processes are 500°C to 700°C, for example.

The above-described statements on the method also apply correspondingly to the laminated pane according to the invention and vice versa.

The invention also includes the use of a composite pane designed according to the invention in a motor vehicle, preferably a passenger car, as a windshield that serves as a projection surface of a projection arrangement for a head-up display. A composite pane designed according to the invention can also be used as a side pane or as a roof pane in a motor vehicle, preferably a passenger car. In these cases, too, the laminated pane can serve as a projection surface of a projection arrangement for a head-up display. The preferred configurations described above apply correspondingly to the use.

The invention is explained in more detail below with reference to drawings and exemplary embodiments. The drawings are schematic representations and not to scale. The drawings do not limit the invention in any way.

Show it:

1 shows a plan view of a composite pane according to the invention as a head-up display with a HUD area,

2 shows a projection arrangement comprising the laminated pane of FIG. 1 in cross section along the section line AA' through the laminated pane of FIG. 1,

3 shows the laminated pane of FIG. 1 with a detailed layer structure of the thermoplastic intermediate layer 3,

4 shows an embodiment of the method according to the invention. FIG. 1 shows a composite pane 1 according to the invention as a windshield, in particular as a windshield of a passenger car, in a plan view. The laminated pane 1 is made up of an outer pane 2 and an inner pane 6 which are connected to one another via a thermoplastic intermediate layer 3 . A functional film 4 is embedded in the thermoplastic intermediate layer 3 . The functional film 4 is a reflective film as a HUD film. The laminated pane has a HUD area B, in which images can be projected onto the windshield by means of a projector. The peripheral edge K of the composite pane 1 is divided into a lower edge U, an upper edge O and two opposite side edges S, which connect the upper edge O and the lower edge U with one another. The lower edge U of the laminated pane 1 is arranged downwards towards the engine of the passenger car, its upper edge O upwards towards the roof. The side edges S run along the A pillars when the laminated pane 1 is installed in a motor vehicle. In the installed position, the outer pane 2 faces the outside environment, and the inner pane 6 faces the vehicle interior. A busbar 5 runs along the top edge O and along the bottom edge U. The busbars 5 make contact with an electrically conductive layer 7. The electrically conductive layer 7 is a heating layer. The reflective film 4 is inserted in the laminated pane 1 in such a way that the reflective film 4 reflects, for example, 20% to 25% of the p-polarized light incident on the film. The functional film 4 has a peripheral edge U, which is set back in the direction of the center of the surface of the composite pane 1 compared to the peripheral edge K of the composite pane 1 . The distance x between the peripheral edge U of the functional film 4 and the busbar 5, which is adjacent to the respective edge section of the edge U, is 20 mm along the entire busbar 5. The laminated pane 1 has no air pockets whatsoever, in particular no air pockets or defects in the area of the bus bar 5 can be detected.

FIG. 2 shows a projection arrangement for a HUD comprising the composite pane 1 of FIG. 1, the projection arrangement being shown as a cross section along the section line AA′ of the composite pane according to FIG. The projection arrangement also includes a projector 12 which is directed onto an area of the laminated pane 1 . In this area, which is usually referred to as HUD area B, images can be generated by the projector 12, which are perceived by a viewer 11 (vehicle driver) as virtual images on the side of the laminated pane 1 facing away from him when his eyes located within the so-called eyebox E. The radiation of Projector 12 is p-polarized, in particular essentially purely p-polarized. Since the projector 12 irradiates the windshield 1 at an angle of incidence of approximately 65°, which is close to Brewster's angle, the radiation from the projector is reflected only insignificantly on the external surfaces I, IV of the composite pane 1 . The reflective film as functional film 4, on the other hand, is optimized for the reflection of p-polarized radiation. It serves as a reflection surface for the radiation of the projector 12 for generating the HUD projection.

FIG. 3 shows the laminated pane of FIG. 1 with a detailed layer structure of the thermoplastic intermediate layer 3. The outer pane 2 and the inner pane 6 consist, for example, of soda-lime glass. The outer pane 2 has an outside surface I (also referred to as the outside of the outer pane), which faces the exterior in the installed position, and an interior surface II (also referred to as the inside of the outer pane), which faces the interior in the installed position. Likewise, the inner pane 6 has an outside surface III (also referred to as the inside of the inner pane), which faces the outside environment in the installed position, and an inside surface IV (also referred to as the outside of the inner pane), which faces the interior in the installed position. The outer pane 2 has a thickness of 2.1 mm, for example, and the inner pane 6 has a thickness of 1.6 mm. The electrically conductive layer 7 in the form of a heating layer is sputtered onto the interior-side surface II of the outer pane 2 . The busbars 5 make electrical contact with the electrically conductive layer 7 , with the laminated pane 1 being able to be heated by applying a voltage to the busbars 5 . The first thermoplastic composite film 3a is formed from a single layer of thermoplastic material, for example a PVB film with a thickness of 0.76 mm or a PVB film with acoustically damping properties with a thickness of 0.81 mm. The second thermoplastic composite film 3b is designed as a PVB film with a thickness of 0.38 mm. The functional film 4 is a reflective film that is arranged between the first thermoplastic composite film 3a and the second thermoplastic composite film 3b. The first thermoplastic composite film 3a and the second thermoplastic composite film 3b are fused to form the thermoplastic intermediate layer 3 and surround the functional film 4 embedded therein. The reflective film 4 is metal-free and suitable, at least 5%, for example 20% to 25%, of the film 4 to reflect incident p-polarized light. The reflective film 4 is 50 μm to 75 μm thick, for example, and is a PET-based film, for example, which is coated with a stack of copolymer layers based on PET and PEN. The reflective film 4 covers the entire surface between the first thermoplastic intermediate layer 3 and the second thermoplastic intermediate layer 5, with the exception of a peripheral edge region R. In the area of the busbar 5, the distance between busbar 5 and the closest section of the peripheral edge U of the functional film is

4 each 20mm. In the remaining peripheral edge area R, no reflective film 4 is arranged in an area with a width of 20 mm to the peripheral edge K of the laminated pane 1 . The laminated pane 1 has an opaque covering print (not shown), which conceals the peripheral edge U and the bus bars 5 .

FIG. 4 shows an embodiment of the method according to the invention at least comprising the steps:

I providing an inner pane 6 or an outer pane 2, an electrically conductive layer 7 being applied to the interior surface II of the outer pane 2 or the outside surface III of the inner pane 6,

II Attaching at least one busbar 5 to the electrically conductive layer 7, the at least one busbar 5 making electrically conductive contact with the electrically conductive layer 7,

III placing a first thermoplastic composite film 3a on the interior surface II of the outer pane 2 or placing a second thermoplastic composite film 3b on the outside surface III of the inner pane 6,

IV application of a functional foil 4, with the peripheral edge U of the functional foil 4 being at a distance of 5 mm to 50 mm from the nearest busbar 5,

V placing a second thermoplastic composite film 3b or placing a first thermoplastic composite film 3a,

VI Closing the stack of layers with an outer pane 2 or an inner pane 6 and laminating to form a composite pane 1.

Steps III to V can be carried out in one or more steps. The functional film 4 can be cut back before or during steps III to V. Reference list:

1 composite pane

2 outer pane

3 thermoplastic intermediate layer 3a first thermoplastic composite film 3b second thermoplastic composite film

4 functional film

5 busbars

6 inner pane

7 electrically conductive layer

10 projection arrangement

11 viewers, vehicle drivers

12 projector

K peripheral edge of the laminated pane 1 U peripheral edge of the functional film 4 x distance between peripheral edge U of the functional film 4 and bus bar 5 R peripheral edge area

B Composite Screen 1 HUD area E Eyebox

O Upper edge of composite pane 1

U Lower edge of composite pane 1

5 side edges of composite pane 1

(I) Outside surface of the outer pane 2 facing away from the intermediate layer 3

(II) Interior side surface of the outer pane 2 facing the intermediate layer 3

(III) outside surface of the inner pane 6 facing the intermediate layer 3

(IV) surface of the inner pane facing away from the intermediate layer 3 on the interior side

6

Claims

patent claims

1. Laminated pane (1) with a functional film (4) at least comprising a peripheral edge (K) of the laminated pane (1), a peripheral edge (U) of the functional film (4), at least one bus bar (5), an outer pane (2) with an outside surface (I) and an inside surface (II), an inner pane (6) with an outside surface (III) and an inside surface (IV) and a thermoplastic intermediate layer (3) covering the inside surface (II) of the outside pane (2) to the outside surface (III) of the inner pane (6), with the functional film (4) being embedded in the thermoplastic intermediate layer (3), the peripheral edge (U) of the functional film (4) opposite the peripheral edge (K ) of the composite pane (1) is set back in the direction of the center of the surface of the composite pane (1), the at least one bus bar (5) between the inside surface (II) of the outside pane (2) and the outside surface (I II) of the inner pane (6) and runs in the edge region (R) of the composite pane (1) between the peripheral edge (K) of the composite pane (1) and the peripheral edge (U) of the functional film (4) and along the at least one Busbar (5), the distance x between the busbar (5) and the peripheral edge (U) of the functional film (4) is between 5 mm and 50 mm.

2. Laminated pane (1) according to claim 1, wherein the distance between the busbar (5) and the peripheral edge (U) of the functional film (4) along the at least one busbar (5) is 10 mm to 30 mm, preferably 15 mm to 25 mm .

3. Laminated pane (1) according to claim 1 or 2, wherein the functional film (4) is based on at least one polyethylene terephthalate (PET), polyethylene (PE), polymethyl methacrylate (PMMA), triacetyl cellulose (TAC) and/or polycarbonate and/or copolymers or mixtures carrier film based thereon, preferably a carrier film based on polyethylene terephthalate (PET).

4. Composite pane (1) according to one of claims 1 to 3, wherein the functional film (4) is a reflective film which is metal-free and is suitable by at least 5%, preferably 10% to 50%, particularly preferably 15% to 30%, in particular 20% to 25%, of p-polarized light incident on the film to be reflected.

5. Laminated pane (1) according to claim 4, wherein the reflective film as the functional film (4) is between 20 μm (microns) and 120 μm, preferably between 30 μm and 90 μm, particularly preferably between 50 μm and 75 μm thick.

6. Laminated pane (1) according to claim 4 or 5, wherein the reflective film as the functional film (4) is a polyethylene terephthalate (PET)-based film that is coated with a copolymer layer stack based on PET and/or polyethylene naphthalate (PEN).

7. Laminated pane (1) according to any one of claims 1 to 6, wherein the at least one bus bar (5) is attached to an electrically conductive layer (7) and makes electrical contact with it.

8. Laminated pane (1) according to claim 7, wherein the electrically conductive layer (7) is applied flatly to the interior surface (II) of the outer pane (2) or the outside surface (III) of the inner pane (6).

9. Laminated pane (1) according to one of claims 1 to 8, wherein the thermoplastic intermediate layer (3) comprises at least a first thermoplastic composite film (3.1) and a second thermoplastic composite film (3.2), between which the functional film (4) is inserted.

10. Laminated pane according to claim 9, wherein the first thermoplastic composite film (3.1) has a thickness of 200 μm to 1000 μm, preferably 300 μm to 850 μm, and the second thermoplastic composite film (3.2) is between 10 μm and 120 μm, preferably between 15 μm and 90 μm, particularly preferably between 20 μm and 75 μm thick.

11. Laminated pane according to one of claims 1 to 10, wherein the first thermoplastic laminated film (3.1) is a film with acoustically damping properties, an intermediate layer absorbing infrared radiation, a colored intermediate layer or a combination of these.

12. A method for producing a composite pane (1) according to any one of claims 1 to 11, wherein a) an inner pane (6) or an outer pane (2) is provided, b) the at least one bus bar (5) is applied, c) a thermoplastic intermediate layer (3) with a functional film (4) is applied and d) the layer stack with a outer pane (2) or an inner pane (6) and laminated to form a composite pane (1), the functional film (4) being cut back before or during step c) and the peripheral edge (U) of the functional film (4) being cut back has a distance of 5 mm to 50 mm to the busbar (5).

13. The method according to claim 12, wherein before or during step a) an electrically conductive layer (7) is applied to the inside surface (II) of the outer pane (2) or the outside surface (III) of the inner pane (6) and the at least a busbar (5) is deposited on the electrically conductive layer (7) in an electrically conductive manner.

14. The method according to claim 12 or 13, wherein during or after step b) and before step d) in the at least one busbar (5) a ventilation structure is embossed.

15. Use of a composite pane (1) according to any one of claims 1 to 11 in one

Motor vehicle, preferably a passenger car, preferably as a windshield.