Heated composite window with acoustically damping properties

Description

[0001] The invention relates to a heated composite disc with acoustic damping properties, a method for its manufacture and its use.

[0002] Laminated glass panes are used in many places today, especially in vehicle manufacturing. The term "vehicle" includes, among other things, road vehicles, aircraft, ships, agricultural machinery, and work equipment.

[0003] Laminated glass panes are also used in other areas. These include, for example, building glazing or information displays, e.g. in museums or as advertising displays.

[0004] A laminated glass pane generally consists of two panes laminated onto an interlayer. The panes themselves may be curved and are usually of constant thickness. The interlayer typically comprises a thermoplastic material, preferably polyvinyl butyral (PVB), of a predetermined thickness, e.g., 0.76 mm.

[0005] Especially in vehicles, but also in buildings, good sound insulation contributes significantly to the quality of the object. It generally dampens the audible sound from the outside environment. In this way, for example, tire noise from one's own vehicle as well as from other vehicles is only perceived as reduced inside the vehicle. This acoustic damping is usually achieved in laminated glass through so-called acoustic interlayers. These acoustic interlayers have a functional layer that absorbs or reflects sound in a specific frequency range.

[0006] EP 1 800 855 A1 describes wedge-shaped multilayer intermediate layers comprising an acoustically damping layer arranged between two protective layers, wherein the wedge shape can be obtained by stretching the multilayer intermediate layers.

[0007] WO 2018 / 081570 A1, US 2016 / 0341960 A1, EP 2 017 237 A1 and WO 2020 / 007610 A1 disclose wedge-shaped multilayer interlayers comprising a layer of constant thickness and a layer with a wedge-shaped cross-section, wherein the layer of constant thickness comprises an acoustically damping layer arranged between two protective layers.

[0008] WO 2021 / 127206 A1 discloses a multilayer acoustic interlayer, wherein the two outer layers are wedge-shaped. The first outer layer also has a thickness at least 10% greater than the second outer layer. In this way, the optical properties can be improved when using the multilayer acoustic interlayer in a head-up display without reducing the noise-dampening effect.

[0009] Another major challenge while driving is heating the windshield to prevent icing or fogging, which impairs visibility. The windshield is typically heated by blowing warm air onto it through inlets. This type of heating is collectively referred to as... Heating, Ventilation and Air Conditioning (HVAC) method. Besides the enormous energy consumption, the inlets through which the hot air is transported and blown onto the disc require a significant amount of space. Furthermore, the outlet nozzles must be positioned in a specific geometric relationship to the disc, which in turn considerably restricts design and construction freedom.

[0010] Alternatively, the pane itself can have an electric heating function. For example, DE 10352464 A1 discloses a laminated glass pane in which electrically heated wires are embedded between two glass panes as a heating element. The specific heating power can be adjusted by the ohmic resistance of the wires. Due to design and safety considerations, the number and diameter of the wires must be kept as small as possible. The wires must be visually imperceptible or barely perceptible in daylight and at night under headlights.

[0011] WO 2013 / 035778 A1 discloses a laminated glass pane with an interlayer comprising an acoustic PVB film and heating wires, wherein the heating wires are arranged on a glass surface of the laminated glass pane and between the interlayer and the glass pane. Similar laminated glass panes are also disclosed in CN 111 775 669 A and CN 111 818 679 A.

[0012] Heating elements are typically embedded between the outer and inner panes within the thermoplastic interlayer. However, these heating elements can be visually noticeable, especially when they come into contact with other functional layers also positioned between the outer and inner panes. The resulting optical distortions reduce the optical quality of the laminated glass. These distortions are usually caused by differing refractive indices for visible light between the heating elements and the functional layers.

[0013] The object of the present invention is therefore to provide an improved heated composite disc which has high optical quality and is largely free from optical distortions.

[0014] The object of the present invention is achieved according to the invention by a composite disk according to claim 1. Advantageous embodiments of the invention are set forth in the dependent claims.

[0015] The composite glass pane according to the invention comprises an outer pane, an inner pane, an acoustic interlayer, and a heating element. The acoustic interlayer is arranged between the inner and outer panes. The acoustic interlayer comprises, in this order, a thicker layer, a functional layer, and a thinner layer. The heating element is arranged within the thicker layer. The thickness of the thicker layer is at least 10% greater than the thickness of the thinner layer. Therefore, the thickness of the thicker layer is at least 110% of the thickness of the thinner layer. Preferably, the thicker layer is arranged closer to the inner pane than to the outer pane. However, the thicker layer can also be arranged closer to the outer pane than to the inner pane. The acoustic interlayer preferably has a thickness typical for thermoplastic interlayers in composite glass panes.Typical layer thicknesses for thermoplastic interlayers are generally known to those skilled in the art. It is understood that the "heating element arranged within the thicker layer" means that the heating element is completely enclosed by the thicker layer. The heating element therefore has no contact with the functional layer, the inner pane, or the outer pane.

[0016] Due to the greater thickness of the thicker layer compared to the thinner layer, the heating element is better embedded within the thicker layer. This largely prevents contact between the heating element and the functional layer located between the thicker and thinner layers. Optical distortions caused by contact between the heating element and the functional layer are reduced, and the optical quality of the laminated glass is improved compared to similar laminated glass with a symmetrical acoustic interlayer. "Symmetrical acoustic interlayer" means that the thicknesses of the thicker and thinner layers are equal or differ by less than 10%.

[0017] A further advantage of the invention is that there is less damage to the laminated glass during lamination, since the heating element has no contact points with the inner or outer pane. Contact between the heating element and the panes creates additional stress during lamination, which in the worst case can lead to breakage of the laminated glass. Likewise, the degassing of the interlayer, i.e., the prevention of gas inclusions in the interlayer, is improved when the heating element is located entirely within the thicker layer.

[0018] The inner pane has an outer surface facing the acoustic interlayer and an inner surface facing away from the acoustic interlayer. The inner surface of the inner pane is also the inner surface of the laminated pane. The outer pane has an outer surface facing away from the acoustic interlayer, which is also the outer surface of the laminated pane. The outer pane also has an inner surface facing the acoustic interlayer. The laminated pane is designed to separate an external environment from an interior space, preferably a vehicle interior. The outer surface of the outer pane is designed to face the external environment, and the inner surface of the inner pane is designed to face the interior space.

[0019] In a preferred embodiment of the invention, the thickness of the acoustic interlayer is from 0.2 mm to 2 mm, preferably from 0.4 mm to 1 mm, and particularly preferably from 0.5 mm to 0.85 mm. The thickness of the acoustic interlayer refers to the sum of the thicknesses of the thicker layer, the thinner layer, the functional layer, and any optional additional layers. The effect of the invention is particularly pronounced within the described thickness range of the acoustic interlayer.

[0020] In a further preferred embodiment of the invention, the thickness of the thicker layer is from 0.1 mm to 1 mm, preferably from 0.15 mm to 0.5 mm, and particularly preferably from 0.2 mm to 0.4 mm. Within the described layer thickness range, particularly good embedding of the heating element in the thicker layer is possible.

[0021] In a further preferred embodiment of the invention, the thickness of the functional layer is from 0.01 mm to 0.5 mm, preferably from 0.05 mm to 0.2 mm, and particularly preferably from 0.08 mm to 0.15 mm. The acoustically damping properties of the functional layer are particularly advantageous in this thickness range with regard to material consumption and the required space.

[0022] Particularly preferably, the thickness of the thicker layer is at least 15%, and more preferably at least 25%, greater than the thickness of the thinner layer. The thickness of the thicker layer is therefore at least 115%, and preferably at least 125%, of the thickness of the thinner layer. Within this thickness range, optical distortions caused by the heating element and the functional layer can be further reduced.

[0023] The heating element can be an electrically conductive film, for example, a metallic film. Preferably, the heating element is designed as an electrically conductive film. The electrically conductive film contains or consists of metal, preferably silver, gold, copper, nickel and / or chromium, or a metal alloy. The heating element particularly preferably contains at least 90 wt.% of the metal, and more preferably at least 99.9 wt.% of the metal. The metal can also be applied to the electrically conductive film as a coating. In an advantageous embodiment, the metallic coating is an electrically conductive layer or a layered structure of several individual layers with a total thickness of less than or equal to 2 µm, and particularly preferably less than or equal to 1 µm.

[0024] The total thickness of all electrically conductive layers is preferably from 40 nm to 80 nm, and particularly preferably from 45 nm to 60 nm. Within this range for the total thickness of all electrically conductive layers, a sufficiently high specific heating power and simultaneously a sufficiently high transmission are advantageously achieved at typical distances h between two busbars for vehicle windows, especially windshields, and an operating voltage U in the range of 12 V to 15 V. Furthermore, the heating element exhibits particularly good reflective properties for the infrared range within this range for the total thickness of all electrically conductive layers. Too small a total thickness of all electrically conductive layers results in excessively high surface resistance and thus insufficient specific heating power as well as reduced reflective properties for the infrared range.Excessive total thickness of all electrically conductive layers reduces the transmission through the disc too much, so that the requirements for the transmission of vehicle discs are not met.

[0025] In a preferred embodiment of the invention, the heating element is formed in the form of thin metal wires, which preferably extend over a large proportion of the surface of the composite disk. The wires may also overlap. The diameter of the metal wires is preferably less than 1 mm, more preferably less than 0.5 mm, and most preferably less than 100 µm, particularly in the range of 10 µm to 30 µm. The metal wires preferably contain at least one metal, preferably silver, gold, copper, nickel, and / or chromium, or a metal alloy. Most preferably, the heating wires contain or consist of tungsten. The heating wires particularly preferably contain at least 90 wt.% of the metal, and more preferably at least 99.9 wt.% of the metal. The effect of optical distortion is particularly significantly reduced when using heating wires.Since the heating wires can come into contact with the functional layer in many different areas of the laminated glass, a halo effect can occur, which reduces the optical quality of the laminated glass. The solution according to the invention largely avoids this problem.

[0026] The functional layer exhibits greater plasticity or elasticity than the surrounding thicker and thinner layers. The functional layer thus has a soft core, with the stiffness of the layer structure increasing from the core of the functional layer towards the outer surfaces of the thicker and thinner layers. The functional layer with higher elasticity is primarily responsible for acoustic damping, while the thicker and thinner layers with lower elasticity contribute significantly to stabilizing the functional layer. The thicker and thinner layers also serve as a thermoplastic bonding material to firmly connect the outer and inner panes.

[0027] In a preferred embodiment of the invention, the thicker layer itself can also be formed from several layers, preferably two layers, such that these several layers fuse together during lamination to form the thicker layer. This is particularly preferred if the heating element is designed as an electrically conductive film. The electrically conductive film can thus be arranged between the at least two layers of the thicker layer before lamination, so that, according to the invention, the electrically conductive layer is located within the thicker layer after lamination.

[0028] In one embodiment, the individual layers of the acoustic intermediate layer, i.e., the thicker layer, the functional layer and the thinner layer, contain independently of one another at least thermoplastic polymers, preferably polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), polyvinyl acetate, polyurethane (PU), acrylates or mixtures or copolymers or derivatives thereof, particularly preferably polyvinyl butyral (PVB), especially polyvinyl butyral (PVB) and plasticizers.

[0029] In a preferred embodiment, the thicker layer, the functional layer, and / or the thinner layer contain polyvinyl butyral and plasticizers. The choice of plasticizer and the degree of acetalization of the polyvinyl butyral allow the elasticity of the polymer layers to be influenced in a manner known to those skilled in the art. Preferably, the functional layer contains a higher percentage of plasticizers than the thicker layer and / or the thinner layer.

[0030] The thicker layer, the functional layer, and / or the thinner layer can be clear and colorless, or tinted, opaque, or colored, independently of one another. The layers can be tinted or colored across their entire surface. Alternatively, the layers can also exhibit a color gradient or a colored pattern. For laminated glass intended as windshields, the tinting or coloring is such that the laminated glass has a light transmission greater than 70% in the spectral range of 380 nm to 780 nm. For laminated glass intended as roof windows or rear side windows, the tinting or coloring can be darker, resulting in a light transmission of 70% or less in the spectral range of 380 nm to 780 nm.It is understood that in embodiments of a windshield, the transmission outside the field of vision, particularly in the area adjacent to the roof edge, may also be less than 70%.

[0031] Plasticizers are chemical compounds that make plastics softer, more flexible, more pliable, and / or more elastic. They shift the thermoelastic range of plastics to lower temperatures, so that the plastics exhibit the desired more elastic properties within the operating temperature range. Preferred plasticizers are carboxylic acid esters, especially low-volatility carboxylic acid esters, fats, oils, soft resins, and camphor. Other preferred plasticizers are aliphatic diesters of triethylene glycols or tetraethylene glycols. 3G7, 3G8, or 4G7 are particularly preferred as plasticizers, where the first digit denotes the number of ethylene glycol units and the last digit the number of carbon atoms in the carboxylic acid moiety of the compound. Thus, 3G8 stands for triethylene glycol bis-(2-ethylhexanoate), i.e., a compound of the formula C 4 H 9 CH (CH 2 CH 3 ) CO (OCH 2 CH 2 ) 3 O 2 CCH (CH 2 CH 3 ) C 4 H 9 .

[0032] Preferably, the PVB-based functional layer contains at least 3 wt.%, more preferably at least 5 wt.%, particularly preferably at least 20 wt.%, even more preferably at least 30 wt.%, and particularly at least 35 wt.% of a plasticizer. The plasticizer contains or consists, for example, of triethylene glycol bis(2-ethylhexanoate).

[0033] If something is "based on" a polymeric material, it consists predominantly, i.e., at least 50%, preferably at least 60%, and particularly at least 70%, of this material. It may therefore also contain other materials such as stabilizers or plasticizers.

[0034] The acoustic interlayer preferably has a constant thickness. The thicker layer, the thinner layer, and the functional layer preferably also have constant thicknesses. However, the thicker layer, the functional layer, and / or the thinner layer can also be wedge-shaped. "Wedge-shaped" means that the layers have the form of a wedge in a cross-sectional view. The wedge-shaped layers therefore do not have a constant thickness, but rather a variable thickness with a thicker first end and a thinner second end. Wedge-shaped layers are particularly preferred when the composite panel is intended to be part of a projection arrangement (e.g., a head-up display). The wedge shape of the acoustic interlayer reduces double images caused by light reflection from the composite panel (visible light is meant here).

[0035] The thicker layer, the functional layer, and / or the thinner layer can be wedge-shaped extruded thermoplastic layers or wedge-shaped stretched thermoplastic layers. A wedge-shaped stretched layer can be obtained by wedge-shaped stretching. The wedge angle of the thicker layer, functional layer, and thinner layer is preferably 0.1 mrad to 1.0 mrad, and more preferably 0.3 mrad to 0.7 mrad, independently of one another.

[0036] In the case of wedge-shaped layers, according to the invention, the respective layer thickness, from which the difference in layer thickness according to the invention between the thicker layer and the thinner layer is calculated, is always based on the area with the thinnest layer thickness with respect to the thicker layer, and always on the area with the thickest layer thickness with respect to the thinner layer. In other words, if the thicker layer is wedge-shaped and the thinner layer is not wedge-shaped, then the thinner end of the thicker layer has a layer thickness at least 10% greater than that of the thinner layer. If, on the other hand, both the thicker layer and the thinner layer are wedge-shaped, then the thinner end of the thicker layer has a layer thickness at least 10% greater than that of the thinner layer.If only the thinner layer is wedge-shaped, then the thicker layer has a thickness that is at least 10% greater than the thicker end of the thinner layer.

[0037] In a particularly preferred embodiment, the heating element extends over at least 10%, preferably at least 30%, particularly preferably at least 80%, and especially at least 90% of the surface of the composite disc. Extending the heating element over a large proportion of the composite disc allows for efficient heating.

[0038] The heating element is preferably electrically connected to at least two external busbars provided for connection to a voltage source. The heating element is connected to the busbars in such a way that a current path for a heating current is formed between them. The busbars are preferably arranged at two opposite edge regions of the heating element. Heating the laminated glass via the heating element eliminates the need for the heating method typically used in vehicle windows, namely Heating, Ventilation and Air Conditioning (HVAC). This reduces the space required in a vehicle. Heating via HVAC requires supply lines that direct the air, usually heated in the engine compartment, to the laminated glass. These supply lines are typically installed in the dashboard of a vehicle and require considerable space.However, electrically heating the laminated glass with the heating element is also advantageous with regard to its use in electric vehicles. In electric vehicles, heating the windshield via the heating element results in energy savings compared to electrically heating air directed onto the laminated glass. Furthermore, it offers greater design flexibility, as the air outlets of HVAC systems must be positioned in a defined geometric arrangement relative to the glass surface to enable the fan function.

[0039] If the heating element of the composite disc according to the invention is designed as an electrically conductive film, it preferably has a surface resistance of less than or equal to 1 ohm / square, particularly preferably from 0.4 ohm / square to 0.9 ohm / square, and most preferably from 0.5 ohm / square to 0.85 ohm / square, for example, approximately 0.7 ohm / square. In this range of surface resistance, advantageously high specific heating powers P are achieved. Furthermore, if the heating element is designed as a coated transparent film, it exhibits particularly good reflective properties for the infrared range in this range of surface resistance.

[0040] In a particular embodiment of the invention, the heating element is connected in an edge region of the outer or inner pane to two busbars provided for connection to a voltage source, such that a current path for a heating current is formed between the busbars. In this context, the heating element preferably extends over 80% or more, and particularly preferably over 90% or more, of the surface of the composite pane. This arrangement allows the majority of the composite pane to be heated efficiently.

[0041] The conductive traces can be formed as a printed and baked-on conductive structure. The printed traces preferably contain at least one metal, a metal alloy, a metal compound, and / or carbon, particularly preferably a precious metal, and especially silver. The printing paste preferably contains metallic particles and / or carbon, and especially precious metal particles such as silver particles. The electrical conductivity is preferably achieved by the electrically conductive particles. The particles can be embedded in an organic and / or inorganic matrix such as pastes or inks, preferably as a printing paste with glass frits.

[0042] The layer thickness of the printed busbars is preferably from 5 µm to 40 µm, particularly preferably from 8 µm to 20 µm, and most preferably from 8 µm to 12 µm. Printed busbars with these thicknesses are technically easy to produce and exhibit advantageous current-carrying capacity.

[0043] The width of the busbars is preferably from 2 mm to 30 mm, particularly preferably from 4 mm to 20 mm, and especially from 10 mm to 20 mm. Thinner busbars result in excessively high electrical resistance and thus excessive heating of the busbar during operation. Furthermore, thinner busbars are difficult to manufacture using printing techniques such as screen printing. Thicker busbars require an undesirably high amount of material.

[0044] The resistivity ρa of the busbars is preferably from 0.8 µΩ·cm to 7.0 µΩ·cm and particularly preferably from 1.0 µΩ·cm to 2.5 µΩ·cm. Busbars with resistivity values ​​in this range are technically easy to implement and exhibit advantageous current-carrying capacity.

[0045] Alternatively, the busbar can also be designed as a strip of electrically conductive foil. The busbar then contains, for example, at least aluminum, copper, tin-plated copper, gold, silver, zinc, tungsten, and / or tin, or alloys thereof. The strip preferably has a thickness of 10 µm to 500 µm, and particularly preferably 30 µm to 300 µm. Busbars made of electrically conductive foils with these thicknesses are technically easy to produce and exhibit advantageous current-carrying capacity. The strip can be electrically connected to the conductive structure, for example, via solder, an electrically conductive adhesive, or by direct bonding.

[0046] In a particularly preferred embodiment, the two busbars are connected to a voltage source, so that a current path is formed between the two busbars through the heating element for a heating current.

[0047] The inner and outer panes are preferably made of glass, particularly soda-lime glass, as is common for window panes. However, the inner and outer panes can also be made of other types of glass, such as quartz glass, borosilicate glass, or aluminosilicate glass, or of rigid, clear plastics, such as polycarbonate or polymethyl methacrylate.

[0048] The inner pane and / or the outer pane may have anti-reflective coatings, non-stick coatings, anti-scratch coatings, photocatalytic coatings, electrically heated coatings, sun protection coatings and / or low-E coatings.

[0049] The thickness of the outer and inner panes can vary widely and thus be adapted to the specific requirements. Preferably, the inner and outer panes have thicknesses of 0.5 mm to 5 mm, and more preferably 1 mm to 3 mm. For example, the outer pane is 2.1 mm thick and the inner pane is 1.6 mm thick. However, the outer pane, or especially the inner pane, can also be made of thin glass with a thickness of, for example, 0.55 mm.

[0050] Preferably, the inner and outer panes do not have a wedge angle. However, it is also possible for the inner and / or outer panes to have a wedge-shaped cross-section. The wedge angle of the composite pane is composed of the wedge angles of the acoustic interlayer, the inner pane, and the outer pane.

[0051] The composite glass according to the invention can be a vehicle window. A vehicle window is designed to separate a vehicle interior from its external environment. A vehicle window is therefore a pane of glass that is installed in, or intended to be installed in, a window opening in the vehicle body. A composite glass according to the invention is, in particular, a windshield of a motor vehicle.

[0052] The inner and outer panes can be clear and colorless, or tinted, opaque, or colored, independently of each other. In a preferred embodiment, the total transmission through the laminated glass is greater than 70%, particularly when the laminated glass is a windshield. The term "total transmission" refers to the procedure for testing the light transmittance of motor vehicle windows as specified in ECE-R 43, Annex 3, Section 9.1. The inner and outer panes can be made of non-tempered, partially tempered, or tempered glass.

[0053] A composite pane according to the invention can additionally comprise a protective print, in particular made of a dark, preferably black, enamel. The protective print is in particular a peripheral, i.e., frame-like, protective print. The peripheral protective print primarily serves as UV protection for the adhesive used to mount the composite pane. The protective print can be opaque and cover the entire surface. The protective print can also be at least partially semi-transparent, for example, as a dot matrix, stripe matrix, or checkered matrix. Alternatively, the protective print can also have a gradient, for example, from an opaque covering to a semi-transparent covering. The protective print is usually applied to the interior surface of the outer pane or to the interior surface of the inner pane.

[0054] The composite disc according to the invention is preferably curved in one or more directions in space, as is common for automotive windshields, with typical radii of curvature ranging from about 10 cm to about 40 m. However, the composite disc can also be flat, for example, if it is intended as a windshield for buses, trains, or tractors.

[0055] The composite disc according to the invention can, for example, be used as part of a head-up display (HUD) or another projection arrangement for displaying information.

[0056] The invention also relates to a method for manufacturing a composite disc wherein (A) A stack of layers is provided, comprising the outer pane, the acoustic interlayer, the heating element, and the inner pane. (B) The heating element is arranged within the thicker layer, preferably by pressing it in. (C) The stack of layers is laminated to form the composite pane.

[0057] In a preferred embodiment of the method according to the invention, the thicker layer of the acoustic interlayer comprises a first layer and a second layer. In the second process step, the heating element is positioned between the first and second layers, so that, according to the invention, the heating element is located within the thicker layer. In the third process step, during lamination, the first and second layers fuse to form the thicker layer, and the thicker layer, the thinner layer, and the functional layer fuse to form the acoustic interlayer. The heating element is thus located within the thicker layer and is completely surrounded by it. This embodiment is particularly preferred when the heating element is designed as an electrically conductive film.

[0058] In the context of the invention, "pressing in" means that the heating element is pressed into the thicker layer by means of applied pressure, preferably while simultaneously heating the thicker layer.

[0059] Lamination of the layer stack can be carried out using conventional lamination processes. For example, so-called autoclave processes can be performed at an elevated pressure of approximately 10 to 15 bar and temperatures of 130 to 145 °C for about two hours. Alternatively, autoclave-free processes are also possible. Well-known vacuum bag or vacuum ring processes, for example, operate at approximately 200 mbar and 80 to 110 °C. The inner disc, acoustic interlayer, and outer disc can also be pressed together in a calender between at least one pair of rollers to form a composite disc. Systems of this type are known for the production of discs and typically have at least one heating tunnel upstream of a press. The temperature during the pressing process is, for example, between 40 to 150 °C. Combinations of calender and autoclave processes have proven particularly effective in practice. Alternatively, vacuum laminators can be used.These consist of one or more heated and evacuated chambers in which the inner and outer panes are laminated within, for example, about 60 minutes at reduced pressures of 0.01 mbar to 800 mbar and temperatures of 80 °C to 170 °C.

[0060] If the laminated glass is to be curved, the inner and outer panes are preferably subjected to a bending process before lamination. Ideally, the inner and outer panes are bent congruently together (i.e., simultaneously and using the same tool) because this ensures that the shape of the panes is optimally matched for the subsequent lamination. Typical temperatures for glass bending processes are, for example, 500°C to 700°C.

[0061] The laminated glass according to the invention can, for example, be the roof window, windshield, side window or rear window of a vehicle or other vehicle glazing, for example a partition in a vehicle, preferably in a rail vehicle, a car or a bus. Alternatively, the laminated glass can be architectural glazing, for example in an exterior facade of a building or a partition inside a building, or a component in furniture or appliances.

[0062] The invention is explained in more detail below with reference to exemplary embodiments, with reference to the accompanying figures. These show, in a simplified representation not to scale: Figure 1 shows a top view of an embodiment of a composite disc according to the invention, Figure 2 shows an enlarged cross-sectional view of the embodiment made of Figure 1Figure 3 shows an enlarged cross-sectional view of a composite disc of the generic type and Figures 4-5 show enlarged cross-sectional views of further embodiments of a composite disc according to the invention.

[0063] Figure 1 Figure 1 shows a top view of a composite disc 100 according to the invention, in particular for use as a windshield of a motor vehicle. Figure 2 shows an enlarged cross-sectional view of the composite disc 100 made of Figure 1 along the intersection line AA' as they Figure 1 as indicated.

[0064] The composite pane 100 has a heating element 4, which is arranged in the form of heating wires between the outer pane 1 and the inner pane 2. The heating element 4 extends over the entire surface of the composite pane 100, with the exception of a thin, circumferential edge region, for example 1 cm wide, which serves for the electrical insulation of the composite pane 100 from the external environment. Two busbars 5 are electrically connected to the heating element 4 at two opposite edge regions of the heating element 4. A first busbar of the two busbars 5 is arranged parallel to a left side edge of the composite pane 100. A second busbar of the two busbars 5 is arranged parallel to a right side edge of the composite pane 100. The spatial designations "left" and "right" refer here to the position of the busbars 5 when viewed from an interior-facing surface of the installed composite pane 100.It is also possible to arrange the busbars 5 parallel to the top and bottom edges of the composite disc 100 (not shown here). The busbars 5 are designed to be connected to a voltage source so that a heating current can flow between the busbars 5 and through the heating element 4. The composite disc 100 can thus be heated by the heating element 4 as needed, thereby removing frost and condensation.

[0065] The laminated glass pane 100 also features a cover print 6, for example, a dark enamel. The cover print 6 is arranged in a frame-like manner around the perimeter of the laminated glass pane 100. The peripheral cover print 6 serves, for example, as UV protection for the mounting adhesive of the laminated glass pane 100. The cover print 6 can be applied to the inner pane 2 or the outer pane 1 (not shown here).

[0066] Figure 2shows an enlarged cross-sectional view of the composite disc 100 in an upper edge area as defined by the section line AA' in Figure 1The composite pane 100 comprises an outer pane 1 and an inner pane 2. An acoustic interlayer 3 is arranged between the outer pane 1 and the inner pane 2. The outer pane 1 has an outer surface I facing away from the acoustic interlayer 3 and an inner surface II facing the acoustic interlayer 3. The inner pane 2 has an outer surface III facing the acoustic interlayer 3 and an inner surface IV facing away from the acoustic interlayer 3. The outer surface I of the outer pane 1 is also the outer surface of the composite pane 100, which, in its installed position, is intended to face an external environment. The inner surface IV of the inner pane 2 is also the inner surface of the composite pane 100, which, in its installed position, is intended to face an interior space.

[0067] The outer pane 1 and the inner pane 2 are made of transparent soda-lime glass, for example. The outer pane has a thickness of 2.1 mm, for example. The inner pane 2 has a thickness of 1.6 mm, for example.

[0068] The cover print 6 is applied to the inner surface II of the outer pane 1. The acoustic intermediate layer 3 comprises, in this order, a thicker layer 3.1, a functional layer 3.2, and a thinner layer 3.3. The thicker layer 3.1 is arranged on the outer surface III of the inner pane 2. Correspondingly, the thinner layer 3.3 is arranged on the inner surface II of the outer pane 1. The heating element 4, in the form of heating wires, is embedded within the thicker layer 3.1 by means of pressure and heat. The thicker layer 3.1 and the thinner layer 3.3 are, for example, made of thermoplastic material. Preferably, the thicker layer 3.1 and the thinner layer 3.3 are based on PVB. The functional layer 3.2 is, for example, made of thermoplastic material and preferably contains PVB. The functional layer 3.For example, layer 2 has a higher proportion of plasticizers than the thicker and thinner layers 3.1 and 3.3.

[0069] The thicker layer 3.1, for example, has a layer thickness a of 0.353 mm. The thinner layer 3.3, for example, has a layer thickness c of 0.307 mm. The layer thickness b of the functional layer 3.2 is, for example, 0.1 mm. The layer thickness of the entire acoustic intermediate layer 3 is, for example, 0.76 mm. According to the invention, the layer thickness a of the thicker layer 3.1 is greater than the layer thickness c of the thinner layer 3.3. The layer thickness a of the thicker layer 3.1 is approximately 15% greater than the layer thickness c of the thinner layer 3.3. The greater layer thickness a of the thicker layer 3.1 allows the heating element 4 to be better embedded in the thicker layer 3.1. The heating element 4 has no, or at least substantially no, contact with the functional layer 3.2. This results in a better optical quality of the composite disc 100. The heating element 4 is better embedded in the thicker layer 3.1 less visually noticeable.

[0070] The Figure 3 shows a generic composite disc 100, which is essentially the variant from the Figures 1 and 2 This corresponds to the fact that only the differences will be discussed here, and otherwise the description of the Figures 1 and 2 is referred to. Unlike the one in Figure 2In the composite disc 100 shown, the thicker and thinner layers 3.1 and 3.3 have the same thickness, for example, 0.33 mm. This means that layer thickness a = layer thickness c. The total thickness of the acoustic intermediate layer 3 is 0.76 mm. Due to the smaller layer thickness a of the thicker layer 3.1 compared to the layer thickness a of the composite disc 100 according to the invention, the heating wires 4 are less effectively embedded in layer 3.1. This reduced embedding of the heating element 4 in the thicker layer 3.1 leads to contact between the heating element 4 and the functional layer 3.2. This results in irregularities in the functional layer 4, which become visible as optical distortion. For the heating wires of the heating element 4, this means they are more visible, as a halo effect is visible at the edge of the heating wires. This impairs the optical quality of the laminated glass 100.

[0071] The in Figures 4 and 5 The variants shown according to the invention essentially correspond to the variant from the Figures 1 and 2 , so that only the differences will be discussed here, and otherwise the description of the Figures 1 and 2 is referred.

[0072] Unlike in Figure 2 The thicker layer 3.1 is shown in Figure 4 The layer does not have a uniform thickness a, but is wedge-shaped. It is evident that the thicker layer 3.1 has a wedge-shaped cross-section with a thicker first end and a thinner second end. In the Figure 4In the embodiment shown, the thickness at the thinner second end of the thicker layer 3.1 is, for example, 0.353 mm. The wedge angle of the thicker layer 3.1 is, for example, 0.55 mrad. The thinner layer 3.3 has, for example, a layer thickness c of 0.307 mm. The thickness a of the thicker layer 3.1 is approximately 15% greater at the thinner second end than the layer thickness c of the thinner layer 3.3. This at least largely prevents contact between the heating element 4 and the functional layer 3.2.

[0073] In the Figure 5In the variant shown, the thicker layer 3.1, the functional layer 3.2, and the thinner layer 3.3 do not have uniform layer thicknesses a, b, c, but are wedge-shaped. Thus, in the cross-sectional view shown, the thicker layer 3.1, the functional layer 3.2, and the thinner layer 3.3 each have a first thicker end and a second thinner end. The second thinner end of the thicker layer 3.1 is, for example, 0.353 mm thick, and the wedge angle of the thicker layer 3.1 is, for example, 0.4 mrad. The second thinner end of the thinner layer 3.3 is, for example, 0.307 mm thick, and the wedge angle of the thinner layer 3.3 is, for example, 0.1 mrad. The second thinner end of the functional layer 3.2 is, for example, 0.09 mm thick, and the wedge angle of the functional layer 3.2 is, for example, 0.1 mrad. This prevents contact between the heating element 4 and the functional layer 3.2, at least to a large extent. Examples

[0074] In the examples according to the invention and the generic comparative examples, the layer thicknesses of the thicker layer 3.1, the functional layer 3.2, and the thinner layer 3.3 were varied. In each example, a composite disk 100 is shown, wherein the examples according to the invention correspond to the structure consisting of Figure 2 are modeled after and the comparison examples reflect the structure from Figure 3 . Table 1. Layer thickness in mm layer Example 1 Example 2 Example 3 Comparative example 1 Comparative example 2 Comparative example 3 inner pane 1,6 1,6 1,6 1,6 1,6 1,6 Thicker layer 0,214 0,353 0,396 0,200 0,330 0,370 Functional layer 0,10 0,10 0,10 0,10 0,10 0,10 Thinner layer 0,186 0,307 0,344 0,200 0,330 0,370 outer pane 2,1 2,1 2,1 2,1 2,1 2,1 Visual defects? No No No Yes Yes Yes

[0075] "Optical defects" refer to increased optical distortions or halo effects that occur due to the contact of the heating element 4 with the functional layer 3.2. The greater layer thickness a of the thicker layer 3.1, compared to the layer thickness c of the thinner layer 3.3, demonstrably prevents, at least to a large extent, optical defects that occur in connection with the heating element 4 and the functional layer 3.2. Reference symbol list

[0076] 1 Outer pane 2 Inner pane 3 Acoustic intermediate layer 3.1 Thicker layer 3.2 Functional layer 3.3 Thinner layer 4 Heating element 5 Busbar 6 Cover print 100 Composite disc I. Outer surface of the outer pane 1 II. Inner surface of the outer pane 1 III. Outer surface of the inner pane 2 IV. Inner surface of the inner pane 2 a) Thickness of the thicker layer 3.1 b) Thickness of the functional layer 3.2 c) Thickness of the thinner layer 3.3 A-A's intersection line

Claims

1. Laminated pane (100) comprising: - an outer pane (1), - an inner pane (2), - an acoustic intermediate layer (3) arranged between the inner pane (2) and the outer pane (1), and - a heating element (4), wherein the acoustic intermediate layer (3) comprises, in this order, a thicker layer (3.1), a functional layer (3.2) and a thinner layer (3.3), and the heating element (4) is arranged within the thicker layer (3.1) and completely enclosed by the thicker layer (3.1), wherein the layer thickness (a) of the thicker layer (3.1) is at least 10% greater than the layer thickness (c) of the thinner layer (3.3), wherein, in the case of wedge-shaped layers, the relevant layer thickness from which the layer thickness difference between the thicker layer (3.1) and the thinner layer (3.3) is calculated is related to the region which has the thinnest layer thickness with regard to the thicker layer (3.1) and to the region which has the thickest layer thickness with regard to the thinner layer (3.3).

2. Laminated pane (100) according to claim 1, wherein the acoustic intermediate layer (3) has a constant layer thickness, and the layer thickness of the acoustic intermediate layer (3) is from 0.2 mm to 2 mm, preferably 0.4 mm to 1 mm, particularly preferably 0.5 mm to 0.85 mm.

3. Laminated pane (100) according to claim 1 or 2, wherein the thicker layer (3.1) has a constant layer thickness, and the layer thickness (a) of the thicker layer (3.1) is from 0.1 mm to 1 mm, preferably 0.15 mm to 0.5 mm, particularly preferably 0.2 mm to 0.4 mm.

4. Laminated pane (100) according to any of claims 1 to 3, wherein the functional layer (3.2) has a constant layer thickness, and the layer thickness (b) of the functional layer (3.2) is from 0.01 mm to 0.5 mm, preferably 0.05 mm to 0.2 mm, particularly preferably 0.08 mm to 0.15 mm.

5. Laminated pane (100) according to any of claims 1 to 4, wherein the layer thickness (a) of the thicker layer (3.1) is at least 15%, preferably at least 25% greater than the layer thickness (c) of the thinner layer (3.3).

6. Laminated pane (100) according to any of claims 1 to 5, wherein the heating element (4) is designed as an electrically conductive foil.

7. Laminated pane (100) according to any of claims 1 to 5, wherein the heating element (4) is designed in the form of wires.

8. Laminated pane (100) according to any of claims 1 to 7, wherein the thicker layer (3.1) and / or the thinner layer (3.3) contains or consists of polyvinyl butyral, ethylene vinyl acetate, polyvinyl acetate and / or polyurethanes.

9. Laminated pane (100) according to any of claims 1 to 8, wherein the functional layer (3.2) has a higher proportion of plasticizers than the thicker and the thinner layer (3.1, 3.3).

10. Laminated pane (100) according to any of claims 1 or 4 to 9, wherein the thicker layer (3.1) and / or the thinner layer (3.3) are wedge-shaped.

11. Laminated pane (100) according to any of claims 1 to 10, wherein the heating element (4) extends over at least 80% of the surface of the laminated pane (100).

12. Laminated pane (100) according to any of claims 1 to 11, wherein the heating element (4) is electrically conductively connected to at least two busbars (5) in two opposite edge regions.

13. Laminated pane (100) according to claim 12, wherein the two bus bars (5) are connected to a voltage source such that a current path through the heating element (4) for a heating current is formed between the two bus bars (5).

14. Method for producing a laminated pane (100) according to any of claims 1 to 13, wherein (A) a layer stack comprising the outer pane (1), the acoustic intermediate layer (3), the heating element (4), and the inner pane (2) is provided, (B) the heating element (4) is arranged within the thicker layer (3.1), preferably by means of pressing, and is completely enclosed by the thicker layer (3.1), and (C) the layer stack is laminated to form the laminated pane (100).

15. Use of a laminated pane (100) according to any of claims 1 to 13 in means of transportation for traffic on land, in the air, or in water, preferably in motor vehicles, for example as a windshield, rear window, side windows, and / or glass roof, particularly preferably as a roof pane or as a functional and / or decorative individual piece and as a built-in part in furniture, devices, and buildings.