Composite glass pane with embedded functional film

Abstract

The invention relates to a composite glass pane comprising an outer glass pane (1) and an inner glass pane (2), which are connected to one another by a thermoplastic intermediate layer, wherein the composite glass pane has an opaque masking region (M) and a transparent see-through region (D), and wherein the intermediate layer comprises - a functional film (3) having at least one layer based on polyethylene terephthalate (PET), which is arranged at least partially in the masking region (M), - an outer thermoplastic layer or layer sequence, by which the functional film (3) is connected to the outer glass pane (1), and - a transparent inner thermoplastic layer or layer sequence, by which the functional film (3) is connected to the inner glass pane (2), and wherein the outer thermoplastic layer or layer sequence has at least one first outer connecting layer (4), which consists of at least one transparent connecting film (4a) and at least one opaque connecting film (4b), wherein the transparent connecting film (4a) is arranged in the see-through region (D) and the opaque connecting film (4b) forms at least a portion of the masking region (M).

Description

[0001] This invention relates to a composite glass plate with an embedded functional membrane, its manufacturing method, and its uses.

[0002] Composite glass panels are commonly used, particularly in the transportation sector, as so-called composite safety glass, especially as windshields, but increasingly also as sunroofs, side windows, or rear windows. Composite glass panels consist of an outer glass panel and an inner glass panel, which are connected to each other by a thermoplastic interlayer. This interlayer is typically formed by at least one connecting film, mostly a PVB film.

[0003] It is known to provide additional advantageous properties to composite glass panels through functional films. Functional films are typically formed based on PET or at least contain PET sheets. Since PET itself has no adhesive effect on the vitreous glass panel, it is inserted between two connecting films in the intermediate layer to embed the functional film into the composite glass panel. For example, a common type is a functional film comprising a PET carrier film and a conductive coating applied thereon, the conductive coating typically containing at least one silver layer. Such functional films provide infrared reflectivity to the composite glass panel, thereby reducing heat input into vehicles. Alternatively, they can also act as reflective surfaces, for example, to reflect radiation pointed at them by projectors, thereby enabling the display of images for the driver. Composite glass panels with PET-based functional films are known, for example, from US6280847B1, DE19534420A1, and WO0160604A1. Alternatively, purely dielectric functional films can also be used, comprising multiple polymer layers in which layers with higher and lower refractive indices are alternately arranged. In this case, at least some layers are typically also formed based on PET. Reflective properties can also be achieved through interference effects with such functional films, such as the reflection of IR radiation or visible radiation from projectors. Composite glass plates with this functional membrane are known, for example, from WO03099553A1.

[0004] One problem arising from the use of these PET-based functional films is that they exhibit different shrinkage properties compared to typical bonding films (such as PVB films). This leads to what is known as… Orange peel effect ( orange skin effect )- Deflection, caused by deformation at the interface between the functional film and the adjacent connecting film, resulting in optical distortion that is particularly noticeable and disruptive in reflection.

[0005] In the field of transportation, composite glass panels typically have a surrounding, opaque outer masking region that surrounds a transparent central viewing area. This opaque masking region primarily serves to protect the adhesive used to bond the composite glass panel to the vehicle body from UV radiation. If the composite glass panel is equipped with electrical functions (such as heating), the necessary electrical connections can also be masked within the masking region. This masking region is typically formed by a black overprint on the surface of the outer glass panel facing the intermediate layer. It has been shown that the orange peel effect is particularly noticeable in this masking region, possibly especially due to the high contrast against the opaque background.

[0006] According to DE202019103729U1, a composite glass plate is known, in which an opaque layer in the middle layer forms a masking area.

[0007] US2020254731A1 discloses a composite glass sheet in which an opaque region of the interlayer forms a masking region. For this purpose, an opaque film segment is inserted into a notch in the transparent interlayer. This is done by avoiding black overprinting, particularly to avoid optical distortions near the masking region, which can occur, for example, during glass bending processes due to the different thermal absorption properties of the masking and transparent regions. In some embodiments, the interlayer is composed of multiple sheets and includes a PET-based functional film between two PVB-based connecting layers, wherein which elements of the multilayer interlayer in the masking region are replaced by the opaque film segment is not disclosed.

[0008] A composite glass plate is known from US2020290319A1, wherein a masking region is formed by additionally inserting a thin, opaque polymer film into an intermediate layer. Here, the intermediate layer is also composed of multiple sheets in some embodiments and includes a PET-based functional film between two PVB-based connecting layers.

[0009] The object of this invention is to provide a composite glass plate having a PET-based functional film, wherein the orange peel effect is less noticeable and intrusive. Furthermore, an advantageous method for manufacturing such a composite glass plate is intended.

[0010] The composite glass panel according to the invention comprises an outer glass panel and an inner glass panel, which are connected to each other by a thermoplastic interlayer. The composite glass panel is provided for separating an interior environment from an exterior environment in window openings (particularly window openings of vehicles, but also window openings of buildings or rooms). In the context of this invention, the inner glass panel refers to the glass panel of the composite glass panel facing the interior space. The outer glass panel refers to the glass panel facing the exterior environment. The composite glass panel is preferably a vehicle glass panel, such as window glass for motor vehicles, rail vehicles, ships, or aircraft. It is particularly preferred as a windshield, side window, rear window, or sunroof glass for passenger cars or trucks, and very particularly preferred as a windshield.

[0011] The outer and inner glass panels each have an outer and an inner space surface (main surface) and a surrounding side edge extending between them. In the context of this invention, the outer surface refers to the main surface that faces the external environment in the mounting position. In the context of this invention, the inner space side surface refers to the main surface that faces the inner space in the mounting position. The inner space side surface of the outer glass panel and the outer surface of the inner glass panel face each other and are connected to each other by a thermoplastic interlayer.

[0012] The composite glass panel according to the invention has an opaque masking region and a transparent viewing region. In the context of this invention, the masking region refers to the area of ​​the composite glass panel through which no light can pass. The light transmittance of the masking region is preferably substantially 0%. In the context of this invention, the viewing region refers to the area of ​​the composite glass panel through which light can pass, and thus has a certain degree of transparency or at least translucency. The light transmittance of the viewing region is preferably at least 10%, particularly preferably at least 20%, and very particularly preferably at least 50%. The light transmittance is very particularly preferably at least 70%, especially when the composite glass panel is used as a windshield for a vehicle, for which the total transmittance must be greater than 70% (determined by the test method for light transmittance of motor vehicle glass panels as defined in ECE-R 43, Annex 3, §9.1).

[0013] In a typical implementation, the masking region surrounds the viewing area in a frame-like manner. That is, the masking region is arranged to encircle the viewing area. In this case, the masking region typically forms at least partially the edge region of the composite glass panel. This means that the masking region is adjacent to at least a segment of the side edge of the composite glass panel. The masking region typically forms the entire surrounding edge region of the composite glass panel.

[0014] According to the present invention, the intermediate layer has a multilayer structure. It includes a functional film having at least one layer based on polyethylene terephthalate (PET). The functional film is disposed between an outer thermoplastic layer or layer sequence and an inner thermoplastic layer or layer sequence. It itself generally does not have adhesive properties to the outer and inner glass plates. The thermoplastic layer or layer sequence ensures that the glass plates are bonded into a composite glass plate, and the thermoplastic layer or layer sequence has adhesive properties to both the outer and inner glass plates. The functional film is bonded to the outer glass plate via the outer thermoplastic layer or layer sequence and to the inner glass plate via the inner thermoplastic layer or layer sequence.

[0015] According to the invention, the functional film is at least partially disposed in the masking region of the composite glass plate. It can be disposed completely or only partially in the masking region. In the latter case, the functional film has at least one area disposed in the masking region and at least one additional area disposed in the transparent region. In this case, the functional film can completely cover the transparent region or only partially cover the transparent region.

[0016] According to the invention, the inner thermoplastic layer or layer sequence is transparent. It preferably has a single inner connecting layer, but may also include multiple inner connecting layers arranged planarly stacked on top of each other. Each inner connecting layer (or the single inner connecting layer) is preferably formed by a single transparent thermoplastic connecting film. Alternatively, a polymer coating may be used on the inner glass plate and / or the functional film, particularly when the thermoplastic layer involved is to be formed very thin.

[0017] According to the present invention, the outer thermoplastic layer or layer sequence has at least one first outer connecting layer. The first outer connecting layer has transparent and opaque regions. For this purpose, it consists of two different connecting films, namely a transparent connecting film and an opaque connecting film. The opaque connecting film contains a colorant (pigment or dye) at a concentration sufficient to achieve opacity. The transparent and opaque connecting films are arranged side by side (relative to the perspective direction through the composite glass plate), so that they are arranged in a plane of the composite glass plate, wherein the opaque connecting film is arranged in the opaque region and forms the opaque region, while the transparent connecting film is arranged in the transparent region and forms the transparent region. In the opaque region, the first outer connecting layer specifically has only the opaque connecting film and no transparent connecting film. In other words, the opaque region of the first outer connecting layer is formed only by the opaque connecting film, and the transparent region of the first outer connecting layer is formed only by the transparent connecting film. The two films are assembled flush at their side edges, so that they are arranged in a plane and together form a layer (i.e., the first outer connecting layer). Here, the transparent connecting film forms the transparent region of the first outer connecting layer and is arranged in the perspective region of the composite glass plate. The opaque connecting film forms an opaque region of the first outer connecting layer and also forms at least a portion of the masking region of the composite glass plate. This means that the opaque connecting film of the first outer connecting layer is the opaque element that causes a region of the composite glass plate (i.e., the masking region or at least a portion of the masking region) to be opaque and not allow light to pass through. The opaque connecting film is thus arranged in the masking region of the composite glass plate and prevents light to pass through it (or at least through a portion of it), thereby making it an opaque masking region.

[0018] In other words, the first outer connecting layer includes a transparent viewing area formed by at least one transparent connecting film and an opaque masking area formed by at least one opaque connecting film. The opaque masking area of ​​the first outer connecting layer at least partially forms the masking area of ​​the composite glass plate.

[0019] The first connecting layer can be a single thermoplastic layer with opaque areas. However, multiple thermoplastic layers with opaque areas can also be used, either in direct contact with each other or separated by at least one transparent connecting film, although this is not preferred because it complicates the structure and manufacturing of the composite glass panel. The opaque areas of different layers can be arranged to overlap, thus forming a masking area together, or they can be staggered, thus forming separate masking areas (more precisely, different segments of the masking area).

[0020] In the context of this invention, an opaque film is understood to be a film having a transmittance of less than 5%, particularly 0%, in the visible spectral range. A transparent film is understood to be a film having a transmittance of greater than 10%, preferably greater than 50%, and particularly preferably greater than 80%.

[0021] It is possible that the opaque connecting film of the first outer connecting layer forms the entire masking area of ​​the composite glass plate. However, it is also possible that only a portion of the masking area is formed by the opaque connecting film of the first outer connecting layer, while the remainder of the masking area is formed by another opaque element, particularly a cover print (preferably on the inner space side surface of the outer glass plate). In this case, the functional film is preferably not arranged in the portion of the masking area formed by the cover print, but only in the portion of the masking area formed by the opaque connecting film of the first outer connecting layer, and optionally in the transparent area. This may occur, for example, when the functional film overlaps only a segment of the surrounding peripheral masking area, for example, along the lower edge of the composite glass plate. Then, for example, the masking area along the lower edge can be formed by the opaque connecting film, and the masking area along the upper and side edges can be formed by a conventional cover print.

[0022] In conventional composite glass panels, the opaque masking areas are formed by an opaque, typically black, overprint, usually applied at least to the inner space side surface of the outer glass panel. This overprint typically consists of enamel applied by screen printing and then fired, the enamel comprising glass frit and colorants (particularly pigments). In contrast, the masking areas of the composite glass panel according to the invention are formed by an opaque connecting film, which forms an area of ​​the first outer connecting layer. The inventors have surprisingly discovered that the orange peel effect induced by the functional film is less noticeable against the background of the opaque connecting film than against the background of the opaque overprint. This significantly improves the appearance of the composite glass panel because the observer perceives the orange peel effect less intrusively. This is a major advantage of the invention. The inventors estimate that the roughness of common overprints enhances the orange peel effect or its visibility, which can be avoided by replacing it with an opaque connecting film.

[0023] The basic idea of ​​this invention is to replace the conventional overprinting in the entire or at least part of the masking area with an opaque connecting film of the first outer connecting layer. If the entire masking area is formed by the opaque connecting film, the composite glass panel preferably has no overprinting on either the outer or inner glass panel. If only a partial masking area is formed by the opaque connecting film, the remaining portion of the masking area is preferably formed by overprinting, which is preferably disposed at least on the inner space side surface of the outer glass panel, and optionally additionally on the inner space side surface of the inner glass panel. Of course, the opaque connecting film and the overprinting can overlap in the partial masking area, particularly where the portions of the masking area formed by the overprinting and those formed by the opaque connecting film are adjacent to each other. However, the overprinting does not completely overlap with the opaque connecting film, so at least a portion of the masking area is formed solely by the opaque connecting film and there is no overprinting in that portion; that is, no opaque overprinting is provided on the outer and inner glass panels. Such overprinting is particularly widely used in the field of transportation equipment. Overprinting typically comprises pigments and glass frit. The glass frit can be melted, allowing the overprint to permanently bond (fuse) to the glass surface. The pigment provides opacity to the masked areas. The overprint is preferably printed on the outer glass plate, particularly by screen printing. The pigment is typically a black pigment, such as carbon black, aniline black, bone black, iron oxide black, spinel black, and / or graphite. The thickness of the overprint is preferably 5 μm to 50 μm, particularly preferably 8 μm to 25 μm.

[0024] The outer and inner thermoplastic layer sequences preferably have a thickness of 0.005 mm to 1.6 mm, respectively. The outer and inner thermoplastic layers or layer sequences may have the same thickness, which is preferably 0.3 mm to 1.0 mm, for example 0.3 mm to 0.6 mm or 0.7 mm to 1.0 mm.

[0025] In an advantageous embodiment, the outer thermoplastic layer or layer sequence is formed to be thicker than the inner thermoplastic layer or layer sequence. This has the advantage of further improving the reflective optics of the composite glass plate and thus its appearance. Through the thin inner thermoplastic layer or layer sequence, the PET-based functional film is very firmly bonded to the inner glass plate, thereby allowing for less severe shrinkage, resulting in less pronounced orange peel effect. In particular, when the composite glass plate is part of a projection device and is illuminated by an imaging unit (e.g., a projector) via the inner glass plate, a thin inner thermoplastic layer or layer sequence is also advantageous for the quality of the displayed image. The thickness of the inner thermoplastic layer or layer sequence is preferably 0.005 mm to 0.55 mm, particularly preferably 0.03 mm to 0.5 mm, and very particularly preferably 0.035 mm to 0.4 mm. It is preferably formed from a single transparent connecting film. The thickness of the outer thermoplastic layer or layer sequence is preferably 0.3 mm to 2 mm, particularly preferably 0.6 mm to 1.6 mm, and very particularly preferably 0.7 mm to 1.0 mm. The stability of the composite glass plate and the shielding against interfering noise are improved by using a thicker outer thermoplastic layer or layer sequence.

[0026] The outer and inner thermoplastic layers or layer sequences are preferably formed based on polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), or polyurethane (PU), with PVB being particularly preferred. This means that the film mainly comprises the aforementioned materials (in greater than 50% by weight) and may optionally contain other components, such as plasticizers, stabilizers, UV or IR absorbers. Each layer of the thermoplastic layer or layer sequence is preferably formed from a film (connecting film) of the corresponding material. Each film forms a thermoplastic layer, except for the first outer thermoplastic layer, which consists of two different films (a transparent and an opaque connecting film). The thickness of each thermoplastic film is preferably from 0.03 mm to 1 mm. For example, films with standard thicknesses of 0.38 mm or 0.76 mm, particularly PVB films, can be used. Polymer coatings can also be used instead of films, especially if the thermoplastic layers involved are to be formed very thinly.

[0027] In a preferred embodiment, the outer thermoplastic layer sequence includes at least one additional outer connecting layer besides the first outer connecting layer, particularly exactly one additional outer connecting layer, referred to as the second outer connecting layer. The second outer connecting layer is preferably transparent. It is preferably formed by a single transparent thermoplastic connecting film or by a thin polymer coating. The first and second outer connecting layers are arranged in a planar stacked arrangement to form the thermoplastic layer sequence. The second outer connecting layer is arranged closer to the functional film than the first outer connecting layer, i.e., having a smaller distance to the functional film than the first outer connecting layer. Therefore, the layers are arranged in the following order: outer glass plate - first outer connecting layer - second outer connecting layer - functional film. The first and second outer connecting layers are preferably in direct contact with each other. The outer thermoplastic layer sequence preferably does not include any other layers besides the first and second outer connecting layers, so that the first outer connecting layer is in direct contact with the outer glass plate and the second outer connecting layer is in direct contact with the functional film. In a particularly preferred embodiment, the composite glass plate consists only of the following layers in the given order: outer glass plate - first outer connecting layer - second outer connecting layer - functional film - inner connecting layer - inner glass plate. This embodiment has particular advantages due to manufacturing: the integrally formed second outer connecting layer, functional film, and inner connecting layer can be joined into an easily manipulated multilayer film, which is inserted between the glass plates during the manufacture of the composite glass plate, thereby simultaneously positioning the three layers. The thicknesses of the first outer connecting layer, the second outer connecting layer, and the inner connecting layer are preferably from 0.005 mm to 0.55 mm, particularly preferably from 0.03 mm to 0.5 mm, and very particularly preferably from 0.035 mm to 0.4 mm. In principle, the outer and / or inner thermoplastic layer sequence may also include additional connecting layers, particularly additional transparent connecting layers. In the case of the outer thermoplastic layer sequence, these additional connecting layers can be arranged between the outer glass plate and the first outer connecting layer, and between the first outer connecting layer and the functional film.

[0028] In another embodiment, in addition to the first outer connecting layer, the outer thermoplastic layer sequence also includes at least one additional outer connecting layer, specifically exactly one additional outer connecting layer, referred to as the second outer connecting layer. The second outer connecting layer is preferably transparent. It is preferably formed by a single transparent thermoplastic connecting film or by a thin polymer coating. The first and second outer connecting layers are arranged in a planar stacked arrangement to form the thermoplastic layer sequence. The first outer connecting layer is arranged closer to the functional film than the second outer connecting layer, i.e., it has a smaller distance to the functional film than the second outer connecting layer. Therefore, these layers are arranged in the following order: outer glass plate - second outer connecting layer - first outer connecting layer - functional film. The first and second outer connecting layers are preferably in direct contact with each other. The outer thermoplastic layer sequence preferably does not include any other layers besides the first and second outer connecting layers, so that the first outer connecting layer is in direct contact with the functional film and the second outer connecting layer is in direct contact with the outer glass plate. In a particularly preferred embodiment, the composite glass plate consists only of the following layers in the given order: outer glass plate - second outer connecting layer - first outer connecting layer - functional film - inner connecting layer - inner glass plate. The thicknesses of the first outer connecting layer, the second outer connecting layer, and the inner connecting layer are each preferably from 0.005 mm to 0.55 mm, particularly preferably from 0.03 mm to 0.5 mm, and very particularly preferably from 0.035 mm to 0.4 mm. In this embodiment, the functional film and the inner connecting layer, which are each integrally formed, can be joined to form an easily manipulated multilayer film, which is inserted between the glass plates during the manufacture of the composite glass plate, thereby positioning the two layers simultaneously. In principle, the outer and / or inner thermoplastic layer sequence may also include additional connecting layers, particularly additional transparent connecting layers. In the case of the outer thermoplastic layer sequence, these additional connecting layers can be arranged between the outer glass plate and the first outer connecting layer.

[0029] In another embodiment, only a single outer thermoplastic layer, namely the first outer connecting layer, exists. The functional film is connected to the outer glass plate only through the first outer connecting layer. There are no other layers between the functional film and the outer glass plate, particularly no transparent connecting layer. Therefore, these layers are arranged in the following order: outer glass plate - first outer connecting layer - functional film. The first outer connecting layer is in direct contact with the outer glass plate and the functional film. In a particularly preferred embodiment, the composite glass plate consists only of the following layers in the given order: outer glass plate - first outer connecting layer - functional film - inner connecting layer - inner glass plate. The thickness of the first outer connecting layer is preferably 0.3 mm to 2 mm, particularly preferably 0.6 mm to 1.6 mm, and very particularly preferably 0.7 mm to 1.0 mm. The thickness of the inner connecting layer is preferably 0.005 mm to 0.55 mm, particularly preferably 0.03 mm to 0.5 mm, and very particularly preferably 0.035 mm to 0.4 mm. In this embodiment, the functional film and the inner connecting layer, which are formed integrally, can also be joined to form an easily manipulated multilayer film, which is inserted between the glass plates during the manufacture of the composite glass plate, thereby positioning the two layers simultaneously. In principle, the inner thermoplastic layer sequence can also include additional connecting layers, particularly additional transparent connecting layers.

[0030] The functional film has at least one layer based on or made of PET. The proportion of PET in said layer is preferably greater than 90% by weight, particularly preferably greater than 95% by weight. The layer is preferably composed substantially of PET. In the context of this invention, the functional film may also be referred to as PET-based or PET-containing. It provides and is suitable for equipping a region of a composite glass plate or composite glass plate with additional functionality. In a preferred embodiment, this is a function of reflecting electromagnetic radiation, particularly in the infrared and / or visible spectral range. Therefore, the functional film is preferably a film that reflects IR and / or reflects visible light. The thickness of the functional film is preferably from 20 μm to 200 μm, particularly preferably from 25 μm to 75 μm.

[0031] In a first advantageous embodiment, the functional film comprises a carrier film based on or made of PET and a conductive coating applied thereon. The conductive coating comprises at least one layer based on a metal, particularly silver. This coating has IR reflective properties. It can be used as a sun-protective coating to reduce the transmission of the infrared portion of incident sunlight through the composite glass panel. This reduces heating of the internal space behind the composite glass panel and thus improves thermal comfort. It also typically has (partial) reflective properties in the visible light range, thus acting as a reflective surface of the display system when the functional film is illuminated by an imaging unit (e.g., a projector). The coating is preferably formed transparently, especially when the functional film is also arranged in the transparent area of ​​the composite glass panel. The transmittance of the transparent area is not reduced to a critical level by the conductive coating. Typically, only a thin metal layer (e.g., at most 20 μm thick) and a dielectric layer are used for transparent coatings, particularly for anti-reflection of the metal layer. If the functional film is only arranged in the masking area, the coating does not need to be transparent. In this case, a thicker silver layer can also be used in a mirror-like manner, acting, for example, as a reflective surface of the display system.

[0032] In a second advantageous embodiment, the functional film is a pure dielectric polymer film comprising alternating layers with different refractive indices. The film has no metal coating. It is a pure dielectric layer sequence consisting of alternating polymer layers with higher and lower refractive indices. At least one of these two layer types is based on PET. The other layer type can also be based on PET, wherein the different refractive indices are achieved through suitable additives, based on PET copolymers or based on another polymer, such as PMMA. Optical interference effects are achieved through the alternation of layers with different refractive indices, which can be appropriately configured (particularly by selecting layer thickness and refractive index) for the corresponding application to achieve reflective properties within the desired spectral range. Therefore, IR reflective properties can also be achieved with this film to reduce the transmission of the infrared portion of solar radiation. Reflective properties in the visible spectral range can also be achieved, allowing the functional film to be used as a reflective surface in a display system.

[0033] The functional film can extend to the side edges of the composite glass panel—or extend around it—such that the functional film covers the entire surface of the composite glass panel and the connecting films adjacent to the functional film on both sides do not contact each other, or only to a portion of the surrounding side edges, where the functional film only covers a portion of the composite glass panel. Alternatively, however, the functional film can also only cover a portion of the composite glass panel and not extend to the side edges. Then the connecting films adjacent to the functional film on both sides contact each other around the entire side edge of the functional element, and the functional film is completely encapsulated in the intermediate layer and not exposed to the surrounding atmosphere. The latter is particularly advantageous when the functional film has a metallic coating, thus providing corrosion protection.

[0034] The outer and inner glass panes are preferably vitreous glass panes, particularly preferably made of soda-lime glass, as is commonly used for window glass. However, one or both glass panes may also be made of other types of glass, such as quartz glass, borosilicate glass, or aluminosilicate glass, or of rigid, colorless, transparent plastic, such as polycarbonate or polymethyl methacrylate. The glass panes may be colorless and transparent, colored, or tinted. The thickness of the outer and inner glass panes is preferably 0.5 mm to 5 mm, particularly preferably 1 mm to 3 mm, independently of each other.

[0035] In a preferred embodiment, the outer surface of the outer glass panel has no coating or markings—it appears as if it were completely exposed and uncoated. The remaining surfaces of the glass panel may have coatings commonly used in the art, particularly clear coatings. For example, this is suitable for… - The sun-protective coating (mostly silver-containing) on ​​the inner surface of the outer glass panel reflects the infrared portion of solar radiation. - A so-called low-E coating on the inner space side surface of the inner glass plate, which reflects the thermal radiation of the composite glass plate, for example, using a layer based on a transparent conductive oxide (TCO) such as ITO. - Anti-reflective coating, for example, on the inner space side surface of the inner glass panel.

[0036] The composite glass panel is preferably curved in one or more spatial directions, as is common, particularly for motor vehicle glass panels. In this case, the typical radius of curvature is from about 10 cm to about 40 m. Here, the inner spatial side surface of the inner glass panel is typically concave, while the outer side surface of the outer glass panel is convex.

[0037] Furthermore, the present invention includes a projection device. The projection device comprises a composite glass panel and an imaging unit according to the invention. The imaging unit irradiates a functional film via an inner glass panel with electromagnetic radiation in the visible spectrum to produce a display image that can be perceived by a user located in the interior space. The imaging unit is thus arranged on the interior space side of the composite glass panel and irradiates the composite glass panel via the interior space side surface of the inner glass panel. The radiation from the imaging unit is (partially) reflected on the functional film. The irradiation area of ​​the functional film may be located in the transparent area and / or the masking area of ​​the composite glass panel. In the transparent area, a so-called head-up display (HUD) can be implemented, which projects information into the driver's field of vision without requiring them to take their eyes off the roadway. In the masking area, the display can also be useful or desirable for aesthetic reasons. Thus, for example, a display that has traditionally been placed in the dashboard of a vehicle can be integrated into the composite glass panel. In the case of the projection device, the composite glass panel is preferably the windshield of the vehicle.

[0038] The imaging unit can be, for example, a projector or an electronic display (“display”), such as an LCD, LED, or TFT display. A projector may be preferred – thereby optionally generating a good and high-intensity display image in the visible or masked area. Alternatively, a display as an imaging unit may be advantageously used, especially for displaying images in the masked area.

[0039] The area of ​​the composite glass plate illuminated by the imaging unit to generate the displayed image is referred to as the display area in the context of this invention.

[0040] In a preferred embodiment, the imaging unit illuminates a functional film in the masked region. The orange peel effect can be particularly perceptible in reflections. In conventional masked regions formed by covering printed material, the orange peel effect is especially noticeable and will cause interference with the displayed image, particularly optical distortion. It is avoided or at least reduced by the masked region formed according to the invention, thereby improving the optical quality of the displayed image.

[0041] In a particularly advantageous embodiment, the radiation of the imaging unit has a p-polarized component. The p-polarized radiation component is preferably greater than 50% of the radiation of the imaging unit, particularly preferably greater than 70%, and very particularly preferably greater than 90%. In a particularly advantageous embodiment, the radiation of the imaging unit is essentially purely p-polarized – that is, the p-polarized radiation component is 100% or only slightly deviated from it. The description of polarization direction here relates to the plane of incidence of the radiation on the composite glass plate. P-polarized radiation refers to radiation whose electric field oscillates within the plane of incidence. S-polarized radiation refers to radiation whose electric field oscillates perpendicular to the plane of incidence. The plane of incidence is generated by the incident vector and the surface normal of the composite glass plate at the geometric center of the irradiated area. Polarization, i.e., particularly the p- and s-polarized radiation components, is determined at a point in the display area, preferably at the geometric center of the display area. If the composite glass plate is curved, which is often the case, especially in the case of vehicle glass plates, this has an effect on the plane of incidence of the radiation of the imaging unit. Therefore, slightly deviated polarization components may appear in other areas, which is unavoidable for physical reasons.

[0042] The radiation from the imaging unit preferably strikes the composite glass plate at an incident angle of 45° to 70°, particularly 60° to 70°. In an advantageous embodiment, the incident angle deviates from the Brewster angle by a maximum of 10°. Then, the p-polarized radiation is only slightly reflected on the surface of the composite glass plate. Thus, the functional film is the only significant reflecting surface of the imaging unit's radiation. If the radiation is also significantly reflected on the outer surface of the composite glass plate (air-glass transition), multiple images will appear, which will be at least intrusive, if not completely unacceptable, to the user. The incident angle is the angle between the incident vector of the imaging unit's radiation and the normal to the inner space side surface at the geometric center of the display area (i.e., the surface normal on the outer surface of the inner space side of the composite glass plate). In the case of soda-lime glass, commonly used for window glass, the Brewster angle of the air-glass transition is 56.5° (for soda-lime glass with a refractive index of 1.51 at 550 nm). Ideally, the incident angle should be as close as possible to this Brewster angle. However, an incident angle of 65° can also be used, for example, which is commonly used in HUD projection devices and can be implemented without any problems in vehicles, deviating from the Brewster angle by only a tiny degree, so that the reflection of p-polarized radiation increases only negligibly.

[0043] The present invention further includes a method for manufacturing a composite glass plate having an opaque masking region and a transparent viewing region, wherein... (a) An outer glass plate, an outer thermoplastic layer or layer sequence, a functional film having at least one layer based on polyethylene terephthalate (PET), a transparent inner thermoplastic layer or layer sequence, and an inner glass plate are arranged in a planar stacked manner to each other in the given order, wherein the outer thermoplastic layer or layer sequence has at least one first outer connecting layer, which consists of at least one transparent connecting film and at least one opaque connecting film, wherein the opaque connecting film at least partially overlaps with the functional film; (b) The layers are then stacked and laminated into a composite glass plate, wherein an opaque connecting film forms at least a portion of the opaque masking region of the composite glass plate, and a transparent connecting film is disposed in the transparent viewing region of the composite glass plate. During lamination, the intermediate layer is formed of an outer thermoplastic layer or layer sequence, a functional film, and an inner thermoplastic layer or layer sequence, which connects the outer and inner glass plates to each other. The functional film is disposed at least partially in the masking region of the composite glass plate by at least partially overlapping the opaque connecting film with the functional film in step (a) of the method.

[0044] The above-described embodiments and preferred embodiments of the composite glass plate are also applicable to the method described above.

[0045] The thermoplastic layers are preferably arranged by positioning the respective thermoplastic connecting films at their respective locations. However, alternatively, one or both of the adjacent layers may also be equipped with a thin polymer coating.

[0046] In an advantageous embodiment, in method step (a), the transparent connecting layer and the functional membrane are first arranged planarly stacked and permanently and stably bonded together to form a multilayer film (more precisely, a "double layer"), for example, by adhesive or lamination (especially under the influence of temperature). The advantage of a multilayer film is that it can be operated like a single connecting film – the two layers are positioned together in the stack in one step, rather than having to be arranged individually and sequentially in an equal manner. The transparent connecting layer is particularly integrally formed from the transparent connecting membrane, thus allowing for relatively easy fabrication of multilayer stacks.

[0047] Subsequently, the outer glass plate, one or more additional layers of the outer thermoplastic film, the first outer connecting layer, one or more additional layers of the outer thermoplastic film, the intermediate film, and the inner glass plate are arranged in a planar stack in the given order, wherein the multilayer film of the inner glass plate faces the inner connecting layer, so that it forms the inner thermoplastic layer of the composite glass plate after lamination. However, in principle, additional connecting layers, particularly transparent connecting layers, can be inserted between the functional film and the inner glass plate, and then they, together with the inner connecting layer, form the inner thermoplastic layer sequence.

[0048] In a particularly advantageous embodiment, in method step (a), a transparent inner connecting layer, a functional film, and a transparent second outer connecting layer are first arranged planarly and permanently bonded together in a given order to form a multilayer film (more precisely, a three-layer film, "triple"), for example, by adhesive or lamination (especially under temperature conditions). The functional film is firmly embedded in the multilayer film and, due to the outer connecting layer, has adhesive properties to the glass plate and other connecting layers. The advantage of the multilayer film is that it can be operated like a single connecting film—the three layers are positioned together in a stack in one step, rather than having to be arranged individually and sequentially in an equal manner. The transparent connecting layers are formed integrally from individual transparent connecting films, thus allowing for relatively easy fabrication of the multilayer stack. The fabrication of the multilayer stack involving the first outer connecting layer in the multi-piece formation is more complex.

[0049] Subsequently, the outer glass plate, the first outer connecting layer, the multilayer film, and the inner glass plate are arranged in a planar stack in the given order, wherein the inner connecting layer of the multilayer film faces the inner glass plate, thus forming the inner thermoplastic layer of the composite glass plate after lamination. The second outer connecting layer of the multilayer film faces the first outer connecting layer, thus forming the outer thermoplastic layer sequence together with the first outer connecting layer after lamination. The manufactured composite glass plate then consists of the following layers in the given order: outer glass plate - first outer connecting layer - second outer connecting layer - functional film - inner connecting layer - inner glass plate. However, in principle, additional connecting layers, particularly transparent connecting layers, can be inserted. If such an additional transparent connecting layer is arranged between the multilayer film and the inner glass plate, it forms the inner thermoplastic layer sequence together with the inner connecting layer (the inner connecting layer thus becoming part of the inner thermoplastic layer sequence). If such an additional transparent connecting layer is arranged between the multilayer film and the first outer connecting layer or between the first outer connecting layer and the outer glass plate, it becomes part of the outer layer sequence.

[0050] The multilayer film is preferably provided in a large-area form, for example as a roll material significantly larger than the area of ​​a typical composite glass sheet. Suitable pieces are then cut from it during the manufacture of the composite glass sheet, as is common in the case of simple connecting films. For this reason, the first outer connecting layer formed in multiple pieces should not be part of a multilayer film in which the arrangement of opaque areas depends on the respective composite glass sheet. Therefore, providing it in large areas as a roll material is not feasible, and the multilayer film can be made from at most multiple pre-cut single layers, which generally does not offer any technological advantage.

[0051] In step (b) of the method, the obtained layers are stacked and laminated into a composite glass plate. This can be done using methods known per se, such as autoclave method, vacuum bag method, vacuum ring method, calendering method, vacuum laminator, or combinations thereof. Here, the bonding of the glass plates is typically achieved through an interlayer under the influence of heat, vacuum, and / or pressure.

[0052] To bend a composite glass sheet, the outer and inner glass sheets are subjected to a bending process before lamination to give them a cylindrical or spherical bent shape. For bending, the glass sheets are softened by heating, making them malleable, and then shaped using methods known per se, such as gravity bending, pressure bending, and / or suction bending. Typical temperatures for glass bending processes are, for example, 500°C to 700°C.

[0053] The present invention further includes the use of the composite glass panel according to the invention in buildings, such as in entrance areas or window areas, or in vehicles of land, air or water transportation, preferably as vehicle glass panels, preferably as windshields, rear windows, side windows or sunroofs of motor vehicles, and particularly as windshields of motor vehicles.

[0054] The invention will be explained in more detail with reference to the accompanying drawings and embodiments. The drawings are schematic illustrations and not drawn to scale. The drawings do not limit the invention in any way. Wherein: Figure 1 A plan view of a general-purpose composite glass plate is shown. Figure 2 shows a cross-section along X-X' through a general composite glass plate according to the prior art. Figure 3 A cross-section along X-X' through one embodiment of the composite glass plate according to the invention is shown. Figure 4 A cross-section along X-X' through another embodiment of the composite glass plate according to the invention is shown. Figure 5 A cross-section along X-X' through another embodiment of the composite glass plate according to the invention is shown.

[0055] Figure 1 A plan view of a general-purpose composite glass panel with an opaque masking region M and a transparent viewing region D is shown. This composite glass panel is, for example, a windshield of a motor vehicle. The masking region M is arranged in the surrounding edge region of the composite glass panel and surrounds the viewing region D. Such masking regions are common in vehicle glass panels—they are used to protect the adhesives used to bond the composite glass panel to the vehicle body from UV radiation. Furthermore, the side edges of possible electrical connections or embedded functional films can be hidden within the masking region M.

[0056] Figure 2 shows a cross-section along section line X-X' of a conventional universal composite glass panel. For simplicity, the composite glass panel is presented as planar, although vehicle glass is typically curved, which is also preferred within the scope of this invention. The composite glass panel comprises an outer glass panel 1 and an inner glass panel 2, which are connected to each other by a thermoplastic interlayer. The outer glass panel 1 and the inner glass panel 2 are made of soda-lime glass. For example, the outer glass panel 1 has a thickness of 2.1 mm, and the inner glass panel 2 has a thickness of 1.6 mm.

[0057] The intermediate layer has a multilayer sheet structure. It contains a functional film 3, which is, for example, composed of a series of polymer dielectric layers, wherein these layers alternately have high and low refractive indices. At least some of these layers are composed of PET. Due to interference, the functional film 3 has reflective properties, such as for IR radiation or visible light. The functional film 3 has, for example, a thickness of 50 μm, covers the entire composite glass plate and extends circumferentially to the side edges of the composite glass plate. It can be used to reduce the transmission of the infrared portion of solar radiation and thereby improve thermal comfort in vehicles. It can additionally or alternatively serve as a reflective surface of a display system, wherein it is illuminated by an imaging unit (e.g., a projector) arranged on the interior space side and reflects the radiation back into the interior space, thereby producing a display image that can be perceived by the driver. This display image can be perceived in the transparent area D (e.g., a head-up display) or in the masked area M.

[0058] The intermediate layer further comprises a transparent outer connecting layer 4' and a transparent inner connecting layer 5. The functional membrane 3 is connected to the outer glass plate 1 via the outer connecting layer 4' and to the inner glass plate 2 via the inner connecting layer 5. The connecting layers 4' and 5 are formed of commercially available PVB film, which also contains a plasticizer. The thickness of the outer connecting layer 4' is 0.76 mm, and the thickness of the inner connecting layer 5 is 0.38 mm.

[0059] The opaque masking area M is formed by a black overlay print 7 on the inner space side surface of the outer glass plate facing the intermediate layer. The overlay print 7 is typically formed of black enamel. It is printed using a screen printing method with printing ink containing black pigment and glass frit, and then fired into the surface of the glass plate.

[0060] The PET-based functional film 3 can induce a so-called orange peel effect, which is particularly visible in reflections and causes optical distortion. It has been shown that this orange peel effect is particularly noticeable in front of the printed material 7.

[0061] In comparison, Figure 3 A cross-section along section line X-X' of one embodiment of the composite glass plate according to the invention is shown. The outer glass plate 1, inner glass plate 2, functional film 3, and inner connecting layer 5 are formed exactly the same as in the conventional embodiment of FIG. 2. However, here, the functional film 3 is connected to the outer glass plate 1 by a sequence of thermoplastic layers including a first outer connecting layer 4 and a second outer connecting layer 6. The second outer connecting layer 6 is formed of a transparent PVB film with a thickness of 0.38 mm. The first outer connecting layer 4 consists of a transparent film 4a and an opaque film 4b, each based on PVB and with a thickness of 0.38 mm. The opaque film 4b prevents visibility through the composite glass plate and thus forms a masking area M. There is no overlay printing as in the case of the conventional composite glass plate of FIG. 2.

[0062] The inventors have determined that the orange peel effect is significantly less noticeable against the background of the opaque film 4b than against the background of the overlaid print 7. The optical distortion is less noticeable and can be seen with the naked eye, and can be used for qualitative comparisons (e.g., for reflections from lamps on composite glass plates). This is a major advantage of the invention.

[0063] The first outer connecting layer 4 faces the outer glass plate 1, and the second outer connecting layer 6 faces the functional film 3. This has the advantage that the second outer connecting layer 6, the functional film 3, and the inner connecting layer 5—each integrally formed—can be joined into a pre-laminated multilayer film before the composite glass plate is manufactured, which is much easier to handle than having to arrange each individual layer in the stack between the glass plates 1 and 2. Conversely, multilayer films involving the multi-piece formation of the first outer connecting layer 4 are more complex to manufacture, mainly because such multilayer films are typically supplied in large quantities as rolls from which the individual pieces required for the composite glass plate are cut.

[0064] Figure 4 A cross-section along section line X-X' of another embodiment of the composite glass plate according to the invention is shown. It has the same characteristics as... Figure 3 The components are identical to those in the implementation scheme, and they are formed exactly the same; however, the two outer connecting layers 4 and 6 are arranged in reverse order. The first outer connecting layer 4 faces the functional membrane 3, and the second outer connecting layer 6 faces the outer glass plate 1.

[0065] Figure 5 A cross-section along section line X-X' of another embodiment of the composite glass plate according to the invention is shown. The outer glass plate 1, the inner glass plate 2, and the inner connecting layer 5 are... Figure 3 and 4 It is formed exactly the same way. Instead of the outer thermoplastic layer sequence, there is a single outer thermoplastic layer, namely the first outer connecting layer 4 with a thickness of 0.76 mm. It is composed of a transparent film 4a in the transparent region D and an opaque film 4b in the masking region M.

[0066] In this case, the functional film 3 is a PET carrier film with a thickness of approximately 50 μm, on which a conductive coating with a silver layer is applied. Because the silver layer is susceptible to corrosion, the functional film 3 does not extend to the side edges of the composite glass plate. Instead, in the surrounding edge region of the composite glass plate, the inner connecting layer 5 and the first outer connecting layer 4 are directly fused together, such that the functional film is encapsulated in an intermediate layer. This functional film 3 is, for example, sold by Eastman under the product name XIR.

[0067] The embodiments shown are to be understood illustratively only and are not intended to limit the invention. In particular, as Figure 5 The functional membrane 3 in the middle can also be with Figure 3 and 4The combination of external thermoplastic layer sequences, and as Figure 3 and 4 The functional membrane 3 in the middle can also be with Figure 5 A single external thermoplastic layer combination. Example

[0068] The orange peel effect is assessed by qualitatively evaluating the reflection of the ceiling light onto the composite glass panel. In an embodiment of the invention, the masking area of ​​the composite glass panel is formed by an opaque film; in a comparative example, it is formed in a conventional manner on the surface of the outer glass panel facing the intermediate layer by a black overlay print (fired enamel with a vitreous glass frit). The inner glass panel faces the ceiling light, and the degree to which the reflected image exhibits ripples due to the orange peel effect is evaluated.

[0069] The following observations were made: - Example: The outline of the reflection from the ceiling light is straight, and the overall reflection is "smooth".

[0070] - Comparative example: The outline of the reflection from the ceiling light shows a distinct wavy shape.

[0071] The inventors attributed this observation to the fact that the orange peel effect in the comparative example was caused or exacerbated by the roughness of the printed material, which could be prevented by using an opaque film.

[0072] List of reference numerals in the attached diagram: (1) Outer glass panel (2) Inner glass plate (3) Functional films based on PET (4) First outer connection layer (4a) The transparent film of the first outer connecting layer 4 (4b) The opaque film of the first outer connecting layer 4 (4') Traditional transparent outer connection layer (5) Inner connection layer (6) Second outer connection layer (7) Covering printed materials XX' section line

Claims

1. A composite glass panel, comprising an outer glass panel (1) and an inner glass panel (2), which are connected to each other by a thermoplastic interlayer. The composite glass panel described therein has an opaque masking area (M) and a transparent viewing area (D). And the intermediate layer includes - A functional film (3) having at least one layer based on polyethylene terephthalate (PET), which is at least partially disposed in the masking region (M), - An outer thermoplastic layer or layer sequence, through which the functional membrane (3) is connected to the outer glass plate (1), and - A transparent inner thermoplastic layer or layer sequence through which the functional membrane (3) is connected to the inner glass plate (2). Furthermore, the outer thermoplastic layer or layer sequence has at least one first outer connecting layer (4), which consists of at least one transparent connecting film (4a) and at least one opaque connecting film (4b), wherein the transparent connecting film (4a) is arranged in the transparent region (D) and the opaque connecting film (4b) forms at least a portion of the masking region (M), and in this portion, the outer glass plate (1) and the inner glass plate (2) do not have opaque overlay printing (7), wherein the opaque connecting film (4b) at least partially overlaps with the functional film (3). The outer thermoplastic layer or layer sequence is formed to be thicker than the inner thermoplastic layer or layer sequence.

2. The composite glass plate according to claim 1, having an outer thermoplastic layer sequence, wherein the outer thermoplastic layer sequence comprises a first outer connecting layer (4) and at least one transparent second outer connecting layer (6) arranged planarly stacked on each other, wherein the second outer connecting layer (6) is arranged closer to the functional film (3) than the first outer connecting layer (4).

3. The composite glass plate according to claim 1, having an outer thermoplastic layer sequence, wherein the outer thermoplastic layer sequence comprises a first outer connecting layer (4) and at least one transparent second outer connecting layer (6) arranged planarly stacked on each other, wherein the first outer connecting layer (4) is arranged closer to the functional film (3) than the second outer connecting layer (6).

4. The composite glass plate according to claim 1, having a single outer thermoplastic layer, wherein the outer thermoplastic layer is a first outer connecting layer (4).

5. The composite glass plate according to any one of claims 1 to 4, wherein the functional film (3) is a pure dielectric polymer film comprising alternating layers with different refractive indices.

6. The composite glass plate according to any one of claims 1 to 4, wherein the functional film (3) is formed as a PET-based carrier film having a conductive coating applied thereon, comprising at least one metal-based layer.

7. The composite glass plate according to claim 6, wherein the metal is silver.

8. The composite glass plate according to any one of claims 1 to 4, wherein the outer thermoplastic layer or layer sequence and the inner thermoplastic layer or layer sequence are formed based on polyvinyl butyral (PVB), ethylene vinyl acetate (EVA) or polyurethane (PU).

9. The composite glass plate according to any one of claims 1 to 4, wherein the entire masking area (M) is formed by an opaque connecting film (4b), and in this portion, the outer glass plate (1) and the inner glass plate (2) do not have an opaque overlay print (7).

10. A projection device comprising a composite glass plate according to any one of claims 1 to 9 and an imaging unit, the imaging unit irradiating a functional film (3) via an inner glass plate (2) to generate a display image.

11. The projection device according to claim 10, wherein the imaging unit illuminates the functional film (3) via the inner glass plate (2) to generate a display image in the masked area (M).

12. The projection device according to claim 11, wherein the radiation of the imaging unit is p-polarized.

13. A method for manufacturing a composite glass plate having an opaque masking area (M) and a transparent viewing area (D), wherein - The outer glass plate (1), the outer thermoplastic layer or layer sequence, at least one functional film (3) based on polyethylene terephthalate (PET), the transparent inner thermoplastic layer or layer sequence, and the inner glass plate (2) are arranged in a planar stacked manner in the given order. The outer thermoplastic layer or layer sequence has at least one first outer connecting layer (4), which is composed of at least one transparent connecting film (4a) and at least one opaque connecting film (4b). The opaque connecting membrane (4b) at least partially overlaps with the functional membrane (3). - The layers are stacked and laminated into a composite glass plate, wherein an opaque connecting film (4b) forms at least a portion of the masking area (M) of the composite glass plate, in which the outer glass plate (1) and the inner glass plate (2) do not have an opaque overlay print (7), and a transparent connecting film (4a) is arranged in the transparent area (D) of the composite glass plate. The outer thermoplastic layer or layer sequence is formed to be thicker than the inner thermoplastic layer or layer sequence.

14. The method of claim 13, wherein - The transparent inner connecting layer (5) and the functional membrane (3) are arranged and connected in a planar stacked manner to form a multilayer membrane in the given order. - The outer glass plate (1), the first outer connecting layer (4), the multilayer film and the inner glass plate (2) are arranged in a planar stacked manner in the given order. The inner connecting layer (5) of the multilayer film faces the inner glass plate (2), thereby forming an inner thermoplastic layer or a component of an inner thermoplastic layer sequence.

15. The method of claim 13, wherein - The transparent inner connecting layer (5), the functional membrane (3), and the transparent second outer connecting layer (6) are arranged and connected in a planar stacked manner to form a multilayer membrane in the given order. - The outer glass plate (1), the first outer connecting layer (4), the multilayer film and the inner glass plate (2) are arranged in a planar stacked manner in the given order. The inner connecting layer (5) of the multilayer film faces the inner glass plate (2), thereby forming an inner thermoplastic layer or a component of an inner thermoplastic layer sequence. And the second outer connecting layer (6) of the multilayer film faces the first outer connecting layer (4), so that the first outer connecting layer (4) and the second outer connecting layer (6) form an outer thermoplastic layer sequence or a component thereof.

16. Use of the composite glass panel according to any one of claims 1 to 9 in a building.

17. Use of the composite glass panel according to any one of claims 1 to 9 as a vehicle glass panel in a land, air or water transport vehicle.

18. The use according to claim 17, wherein the vehicle glass panel is a windshield of a motor vehicle.

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