Windscreen having improved collision safety and vehicle comprising same
Patent Information
- Application Number
- EP2023715832
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-04-06
- Filing Date
- 2023-03-29
- Publication Date
- 2025-02-12
AI Technical Summary
Thin laminated glass windshields in vehicles face increased risk of breakage during accidents, compromising airbag deployment and overall accident safety due to reduced mechanical strength, which is exacerbated by weight-saving efforts in automotive construction.
A windshield design featuring a thermoplastic intermediate layer with a combination of polymer films, where a stiffer second polymer film is strategically applied in specific areas to enhance mechanical stability and provide necessary counterforce for airbag deployment, while maintaining the advantages of a more flexible first polymer film in other areas.
The design significantly improves accident safety by ensuring optimal airbag deployment and maintaining mechanical stability, even if the windshield breaks, by providing sufficient counterforce and reducing the risk of glass breakage during accidents.
Smart Images
Figure 1.1
Abstract
Description
[0001] WINDSHIELD WITH IMPROVED CRASH SAFETY AND THIS COMPREHENSIVE VEHICLE
[0002] The invention relates to a windshield with improved crash safety, a method for its production and a vehicle comprising a windshield with improved crash safety.
[0003] Laminated glazing, which comprises at least two panes and at least one polymer film bonded between the panes, has been in widespread use for decades in various technical fields, particularly in building glazing and vehicle construction. The selection of materials and the dimensioning of components depend on the requirements of the specific application, particularly with regard to the desired mechanical strength of the finished glazing, taking into account the constraints imposed by the frame and any attachments.
[0004] US 3,437,552 A discloses laminated panes comprising two glass panes and an intermediate polyvinyl butyral (PVB) layer.
[0005] US 6,708,595 B1 discloses a bulletproof laminated glass pane for motor vehicles, which comprises a stacking sequence of several panes and several adhesive intermediate layers in between.
[0006] Particularly in the automotive industry, there is a trend toward the use of thinner and therefore lighter glass in laminated glass panes as part of efforts to reduce weight and thus achieve fuel and energy savings. Nevertheless, these panes must meet defined mechanical requirements laid down in relevant industry standards. This increases safety requirements for vehicle occupants as well as for other road users and pedestrians. In the event of a frontal car accident, the airbag integrated into the steering wheel deploys and protects the driver's head from injuries upon impact. The deployed airbag has a contact area with the windshield, with the airbag pressing against the windshield from the interior surface of the inner pane.This causes the windshield to bend, with the greatest bending tensile stresses occurring on the outer surface of the inner pane and the outer surface of the outer pane. As part of the weight savings sought in automotive engineering, windshields should also be made as light as possible, which is why reduced glass thicknesses are generally used. The reduced glass thickness is associated with lower mechanical strength in the area of the windshield where the airbag comes into contact with the glass. Thin glass increases the risk of glass breakage in the area of the airbag, which leads to suboptimal airbag deployment. The airbag requires sufficient counterforce in the area of the windshield to ensure it expands correctly, which is not the case in the event of glass breakage. This problem also arises if the accident itself has already caused damage to the windshield.
[0007] From DE 10 2019 108 385 A1, EP 0836108 A2, EP 3187917 A2, EP 1804111 A1 and EP 0844507 A1, glazings comprising systems for projecting information are known.
[0008] JP 2008133141 A1 discloses a laminated glazing comprising an interlayer having a first region and a second region. The first region extends along the bottom edge and / or both sides of the glazing, wherein the tensile stiffness of the interlayer is higher in the first region than in the second region.
[0009] The invention is therefore based on the object of providing an improved windshield which enables correct deployment of the airbag even if one or both panes of the windshield break, thus offering greater accident safety.
[0010] This object is achieved according to the invention by a windshield according to claim 1. Advantageous embodiments of the invention emerge from the subclaims.
[0011] The windshield according to the invention comprises at least a first pane and a second pane, which are connected to one another by means of a thermoplastic intermediate layer. The first pane has an outside surface I and an inside surface II. The second pane has an outside surface III and an inside surface IV. When the windshield is installed in a motor vehicle, the outside surfaces of the panes face the vehicle's surroundings, while the inside surfaces each designate the surfaces of the panes facing the vehicle interior. The inside surface II of the first pane is connected to the outside surface III of the second pane via the thermoplastic intermediate layer, wherein the intermediate layer comprises at least a first polymer film with a first stiffness and a second polymer film with a second stiffness.The windshield comprises at least a first surface area in which the thermoplastic intermediate layer comprises at least a first polymer film. The windshield comprises a second surface area in which the thermoplastic intermediate layer contains the second polymer film. The first surface area does not contain a second polymer film. The second stiffness of the second polymer film is higher than the first stiffness of the first polymer film, such that the thermoplastic intermediate layer has improved stiffness in the second surface area. The second surface area comprises at least the contact surface between the deployed driver airbag of a motor vehicle and the windshield based on the installed state of the windshield in a motor vehicle.The greater rigidity of the second polymer film in the second surface area of the windshield ensures greater mechanical stability even in the event of a windshield breakage and provides sufficient counterforce to the airbag as it deploys against the windshield. This ensures flawless deployment of the airbag. The second surface area or areas take up or cover less than 60% of the total surface area of the windshield. If there are multiple second surface areas, the individual areas of the second surface areas are added together. This is advantageous in order to be able to provide a stiffer second polymer film at the required location on the windshield, which improves accident safety while retaining the advantageous properties of the first polymer film in other areas. The greater the rigidity of a polymer film, the less flexible the film, which results in reduced tear resistance and reduced flowability during lamination.The second polymer film with increased stiffness therefore has these disadvantages, whereas the first polymer film shows good tear resistance and flowability when heated. If the second polymer film is applied over the entire surface of the composite pane, a deterioration in the composite quality of the windshield is to be expected. However, if the first polymer film is used over the entire surface and without an additional second polymer film, the desired improved counterforce when unfolding the airbag cannot be achieved. Furthermore, the first polymer film ensures not only a secure connection of the panes but also more advantageous acoustic properties. The surface area of the windshield in which no second polymer film is applied is referred to as the first surface area. The area of the first surface area is calculated from the total surface area of the windshield minus the area of the second surface area.The second polymer film is not applied outside the second surface area. The first polymer film is applied at least in the first surface area, but can also extend into the second surface area. The windshield according to the invention can achieve improved road safety while maintaining the windshield's mechanical stability. According to the invention, the second surface area comprises at least the contact surface between the deployed driver airbag of a motor vehicle and the windshield, based on the installed state of the windshield in a motor vehicle. Windshields are manufactured individually for a specific motor vehicle model.Using this model, the subsequent installation position can be determined even when the windshield is not in the installed state, which means that the contact area of the deployed driver airbag with the windshield can also be determined using the windshield itself.
[0012] The inventors have determined that the stiffer second polymer film only slightly improves the stiffness of the glass laminate before the panes break, and that in an undamaged state, the stiffness of the glass panes themselves is the main factor determining the stiffness of the windshield. After the glass breaks due to an accident or the deployment of an airbag, the stiffness of the glass laminate is greatly reduced, which is also evident in the significant sinking of the windshield as the cracks spread. When the panes break, delamination and stretching of the thermoplastic interlayer comprising the second polymer film occurs in the area of the glass break. The second polymer film with higher stiffness has lower extensibility, meaning the maximum stretch before the film tears is reduced compared to the first polymer film.By incorporating the stiffer second polymer film, the stiffness of the damaged area is significantly higher than with standard windshields that only comprise a first polymer film. As a result, the windshield according to the invention provides a greater counterforce for optimal airbag deployment.
[0013] The windshield is designed to separate the interior of a vehicle from the outside. A windshield is a window pane that is inserted into a window opening in the vehicle body or is intended to be inserted therein. The windshield is set into the opening provided for this purpose between the hood, the roof of the vehicle and the A-pillars of the vehicle body. The edge of the windshield closest to the vehicle's engine compartment when installed is called the engine edge, while the edge opposite the engine edge is called the roof edge and is oriented adjacent to the vehicle roof. The two edges of the windshield that run adjacent to the A-pillars are called the side edges of the windshield and connect the engine edge and the roof edge.The first pane represents the outer pane of the windshield, which faces the outside environment of the vehicle, while the second pane of the windshield forms the inner pane, which is oriented towards the vehicle interior. It is understood that the first pane, the second pane, and the thermoplastic intermediate layer have essentially the same external dimensions. The surface of the respective pane which, in the installed position, faces the outside environment of the vehicle is referred to as the outside surface. The surface of the respective pane which, in the installed position, faces the interior of the vehicle is referred to as the interior surface. The interior-side surface of the outer pane is connected to the outside surface of the inner pane via the thermoplastic intermediate layer.Typically, the outside surface of the outer pane is referred to as “Side I”, the inside surface of the outer pane as “Side II”, the outside surface of the inner pane as “Side III” and the inside surface of the inner pane as “Side IV”.
[0014] The windshield according to the invention has at least one second surface region in which the second polymer film is introduced. There may also be a plurality of second surface regions. No second polymer film is introduced outside the second surface regions. The size of the second surface region can vary, but according to the invention comprises at least the contact surface between the deployed driver airbag of the motor vehicle and the windshield based on the installed state of the windshield in a motor vehicle. The second polymer film and the first polymer film together form the thermoplastic intermediate layer. The first polymer film and the second polymer film can each have a single-layer or multi-layer structure. In one possible embodiment, the first polymer film is embodied as a film laminate and / or the second polymer film is embodied as a film laminate, for example as a film laminate with three layers.Preferably, the first polymer film and the second polymer film are designed as single-layer films.
[0015] According to the invention, the thermoplastic intermediate layer comprises at least a first polymer film with a first stiffness and a second polymer film with a second stiffness. The thermoplastic intermediate layer may further comprise one or more additional films. These may, for example, be films with electrically switchable functions or colored regions.
[0016] The at least one first polymer film and the at least one second polymer film can be applied congruently and / or adjacently to one another in the windshield. Whether the first and second polymer films are congruently or adjacently configured is preferably determined depending on the size of the second surface area.
[0017] The driver's side of a motor vehicle can be located either on the right or left side of the vehicle, as viewed from the vehicle cabin. Accordingly, the at least one second surface area is located on the right and / or left side of the windshield, as viewed from the vehicle cabin in the direction of travel. Preferably, at least one second surface area, which includes the contact surface between the deployed driver airbag and the windshield, lies within the so-called field of vision B of the windshield.
[0018] Windshields have a central field of vision, the optical quality of which is subject to stringent requirements. This central field of vision must exhibit high light transmission (typically greater than 70%). This central field of vision is specifically the field of vision referred to by experts as field of vision B, field of vision B, or zone B. Field of vision B and its technical requirements are defined in Regulation No. 43 of the Economic Commission for Europe of the United Nations (UN / ECE) (ECE-R43, "Uniform provisions concerning the approval of safety glazing materials and their installation on vehicles"). Field of vision B is defined in Annex 18.
[0019] Particularly preferably, the windshield also has a second surface area in the contact area of the passenger airbag with the windshield. This second surface area can be configured either separately or continuously with the second surface area, which comprises the contact area between the driver airbag and the windshield. In the area of the passenger airbag, the second surface area preferably extends from the motor edge to a maximum height of 50% of the height of the windshield, with the height of the windshield resulting from the distance between the motor edge and the roof edge of the windshield.
[0020] In a preferred embodiment, the windshield has only a first surface area and a second surface area, which together cover the entire surface of the windshield. In a further preferred embodiment, the windshield has a continuous first surface area surrounding a plurality of second surface areas. In addition to the second surface area, which covers the contact surface of the deployed driver airbag with the windshield, further second surface areas can be provided, for example, in the area of the contact surface of the deployed passenger airbag with the windshield.
[0021] In principle, it is desirable to cover larger areas with the second polymer film in order to achieve the greatest possible load-bearing capacity of the windshield. However, this is generally not exclusively advantageous due to the lower tear resistance of the second polymer film and for cost reasons.
[0022] Preferably, the second surface area or the second surface areas together occupy less than 50%, preferably 20% to 40%, of the total surface area of the windshield. In the case of multiple second surface areas, the individual areas of the second surface areas are added together. Tests have shown that the aforementioned preferred surface proportions of the second surface area are sufficient to cover the contact surface between the airbag and the windshield. The remaining first surface area is sufficiently large to ensure a good connection of the windshield panes. This allows for improved road safety while maintaining the mechanical stability of the windshield.
[0023] Preferably, the second surface area is surrounded by the first surface area, wherein the first surface area comprises at least one first polymer film. The second surface area is only locally limited to the areas in which this is necessary for accident safety, and in the vicinity of this surface area and the rest of the windshield, optimal connection of the panes is ensured via the at least one first polymer film. Particularly preferably, the first surface area comprises precisely one first polymer film. In particular, the thermoplastic intermediate layer in the first surface area consists of a first polymer film, wherein no further polymer films are applied between the first polymer film and the first pane or between the first polymer film and the second pane.
[0024] In a preferred embodiment, the first polymer film has a cutout in the second surface area, and at least one second polymer film is inserted into this cutout. This is advantageous in order to be able to insert the second polymer film only locally in the areas in which the second polymer film is required. The first polymer film surrounds the second polymer film and, if applicable, other films that may be present in the second surface area, like a passepartout. The cutout in the first polymer film is advantageous in order to achieve the smallest possible thickness deviation between the first surface area and the second surface area and to be able to insert the second polymer film as flush as possible. If the first polymer film is cut out, local thickening of the thermoplastic intermediate layer in the area of the second polymer film can be avoided by inserting the second polymer film precisely into the cutout.Preferably, the cutout of the first polymer film has a rounded geometry; particularly preferably, an elliptical or circular cutout is selected. A rounded geometry is advantageous to avoid faulty lamination and possible air inclusions in corner areas.
[0025] The thermoplastic intermediate layer preferably consists of one or more first polymer films in the first surface area, preferably of exactly one first polymer film. This is advantageous for simplified production and, if a cutout is present in the second surface area, for simplified insertion of this cutout.
[0026] The thermoplastic intermediate layer can be constructed in a single layer or in multiple layers in the second surface region and comprises at least a second polymer film. A single-layer structure in which the thermoplastic intermediate layer in the second surface region consists of a second polymer film is advantageous in order to enable simplified production and simple assembly of the layer stack of the thermoplastic intermediate layer. Furthermore, the thicknesses of the first polymer film and the second polymer film can be selected to be similar or identical so that stresses in the glass caused by local differences in thickness are avoided. In a further preferred embodiment, the thermoplastic intermediate layer in the second surface region consists of a second polymer film and a first polymer film, which are arranged congruently with one another and are inserted into a section of the first polymer film present in the first surface region.This is preferred in order to improve the adhesion and lamination of the thermoplastic intermediate layer in the second surface region. The thicknesses of the second polymer film and the first polymer film within the second surface region are preferably selected such that their sum has the smallest possible deviation from the thickness of the first polymer film located in the first surface region. In a particularly preferred embodiment, a layer stack consisting of this sequence of a first polymer film, a second polymer film and a first polymer film is provided in the second surface region, arranged one on top of the other, from which layer the thermoplastic intermediate layer in this region consists. The first polymer films arranged adjacent to the second polymer film in the second surface region improve the bond of the second polymer film located between them to the glass panes.Even in this configuration, the thickness deviation of the thermoplastic intermediate layer between the first surface area and the second surface area should be as small as possible. Whether the second surface area contains only a second polymer film or whether it should be coated on one or both sides with an adhesion-enhancing first polymer film depends on the material selected for the second polymer film and its adhesion to glass panes.
[0027] To minimize stresses in the windshield glass, the thickness of the thermoplastic intermediate layer in the first surface area is selected such that it deviates by less than 10%, preferably by less than 5%, particularly preferably by less than 2%, from the thickness of the thermoplastic intermediate layer in the second surface area. In particular, the thickness of the thermoplastic intermediate layer in the first surface area is equal to the thickness of the thermoplastic intermediate layer in the second surface area. To determine the thickness of the thermoplastic intermediate layer, the thicknesses of all first and / or second polymer films arranged one above the other in this area between the interior surface of the outer pane and the exterior surface of the inner pane are added together.
[0028] The first polymer film and the second polymer film each comprise one or more individual layers. The thickness of the first polymer film is preferably between 300 μm and 1000 μm, particularly preferably between 350 μm and 850 μm. The thickness of the second polymer film is preferably between 25 μm and 850 μm, with the selected thickness of the second polymer film depending on whether there are first polymer films with overlapping surfaces in the second surface region.
[0029] In a first preferred embodiment, the at least one second surface region takes up less than 60%, preferably less than 50%, of the total surface area of the windshield and is surrounded by a continuous first surface region. A first polymer film is introduced into the first surface region, which first polymer film has a cutout in the region of the second surface region, into which a single second polymer film is inserted. The first polymer film and the second polymer film both have a thickness of 300 μm to 850 μm, preferably 700 μm to 800 μm, wherein the thicknesses of the first polymer film and the second polymer film particularly preferably differ from one another by less than 10%.
[0030] In a second preferred embodiment, the at least one second surface area takes up less than 60%, preferably less than 50%, of the total area of the windshield and is surrounded by a continuous first surface area. A first polymer film is introduced into the first surface area and has a cutout in the area of the second surface area. The cutout of the first polymer film in the first surface area defines the second surface area. A layer stack comprising a second polymer film and a first polymer film is inserted in the second surface area. The first polymer film in the first surface area has a thickness of 600 pm to 850 pm, while the first polymer film in the second surface area has a thickness of 300 pm to 825 pm and the second polymer film in the second surface area has a thickness of 25 pm to 400 pm.Particularly preferably, the total thickness of the thermoplastic intermediate layer in the first surface region, corresponding to the thickness of the first polymer film introduced there, deviates by less than 10% from the thickness of the thermoplastic intermediate layer in the second surface region, defined by the sum of the thicknesses of the first polymer film and the second polymer film introduced there. For example, the first polymer film in the first surface region has a thickness of 760 μm, while a first polymer film with a thickness of 380 μm and a second polymer film with a thickness of 380 μm are introduced in the second surface region.
[0031] In a third preferred embodiment, the at least one second surface area takes up less than 60%, preferably less than 50%, of the total area of the windshield and is surrounded by a continuous first surface area. A first polymer film is introduced into the first surface area and has a cutout in the area of the second surface area. The cutout of the first polymer film in the first surface area defines the second surface area. A layer stack comprising, in this order, a first polymer film, a second polymer film and a first polymer film is inserted in the second surface area. The first polymer film in the first surface area has a thickness of 600 μm to 850 μm, while the first polymer films in the second surface area each have a thickness of 200 μm to 400 μm and the second polymer film in the second surface area has a thickness of 25 μm to 200 μm.Particularly preferably, the total thickness of the thermoplastic intermediate layer in the first surface region, corresponding to the thickness of the first polymer film introduced there, deviates by less than 10% from the thickness of the thermoplastic intermediate layer in the second surface region, defined by the sum of the thicknesses of the first polymer films and the second polymer film introduced there. For example, the first polymer film in the first surface region has a thickness of 760 μm, while in the second surface region, two first polymer films each with a thickness of 380 μm and a second polymer film with a thickness of 50 μm are introduced.In principle, thicker or thinner polymer films can also be used, and even slight differences in thickness between the thermoplastic intermediate layer in the first surface area and the thermoplastic intermediate layer in the second surface area may be acceptable; however, the above-mentioned thickness ranges and thickness matches are technologically advantageous.
[0032] The at least one first polymer film preferably comprises polyvinyl butyral (PVB), polyurethane (PU), ionomers, and / or ethylene vinyl acetate (EVA). These materials have proven particularly suitable for securely bonding the panes to one another.
[0033] The at least one second polymer film preferably comprises polyvinyl butyral (PVB), polyethylene terephthalate (PET), polyurethane (PU), ionomers and / or ethylene vinyl acetate (EVA).
[0034] Preferably, the at least one first polymer film is a film having a modulus of elasticity of less than 20 MPa, while the second polymer film is a film having a modulus of elasticity of greater than 100 MPa, each measured according to standard ASTM D882.
[0035] In a preferred embodiment, the first polymer film is a PVB film with a modulus of elasticity of less than 20 MPa, while the second polymer film is a PVB film or a PET film with a modulus of elasticity of greater than 100 MPa, each measured according to ASTM D882.
[0036] In principle, however, polymer films with a different chemical composition can be used for both the first surface area and the second surface area, provided that they meet the other requirements with regard to transparency and durability and the above-mentioned relationship between the stiffnesses or elastic moduli of the first and second polymer films is maintained.
[0037] The first pane and the second pane are preferably made of glass, particularly preferably soda-lime glass, as is common for window panes. However, the 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. The first pane and the second pane can independently consist of non-tempered, semi-tempered, or tempered glass. If the first pane and / or the second pane are to be tempered, this can be thermally or chemically tempered.
[0038] The first and the second pane preferably each have a thickness of 0.8 mm to 2.5 mm, particularly preferably 1.2 mm to 2.2 mm. The thickness of the first pane is typically from 1.0 mm to 2.5 mm. The thickness of the second pane is preferably between 0.8 mm and 2.1 mm. The thickness of the first pane is preferably greater than the thickness of the second pane. For example, the first pane can be 2.1 mm and the second pane 1.1 mm thick, or the first pane can be 1.8 mm and the second pane 1.4 mm thick, or the first pane can be 1.6 mm and the second pane 1.1 mm thick, or the first pane can be 1.6 mm and the second pane 0.7 mm thick, or the first pane can be 1.4 mm and the second pane 1.1 mm thick.
[0039] The first pane, the second pane, and the thermoplastic interlayer can be clear and colorless, but also tinted or colored. The tint of the outer pane, inner pane, and thermoplastic interlayer is selected depending on the intended application of the laminated pane. For windshields, high transmission in the visible range of the light spectrum is desired, and dark tints of the components are avoided. The total transmission through the windshield, when used as a windshield of a motor vehicle, is greater than 70%, based on illuminant A. The term "total transmission" refers to the procedure for testing the light transmittance of motor vehicle windows specified in ECE-R 43, Annex 3, Section 9.1.
[0040] The windshield according to the invention is preferably curved in one or more directions of space, as is common for motor vehicle windshields, with typical radii of curvature ranging from approximately 10 cm to approximately 40 m. However, the windshield can also be flat, for example, if it is intended for buses, trains, or tractors.
[0041] The first pane, the second pane, and / or the thermoplastic intermediate layer may have further suitable, known coatings, for example anti-reflective coatings, non-stick coatings, anti-scratch coatings, photocatalytic coatings, sun protection coatings, or low-E coatings. Automotive glazing, in particular windshields, rear windows, and roof windows, usually has a peripheral masking print made of an opaque enamel, which serves in particular to protect the adhesive used to install the pane from UV radiation and to visually conceal it. Preferably, at least the first pane used as the outer pane has such a masking print; particularly preferably, both the first pane and the second pane (inner pane and outer pane) are printed, so that visibility from both sides is prevented.The opaque masking print is applied, for example, in the form of a screen print, so that this screen print defines the viewing area of the pane or forms its outer edge. Any electrical conductors located in the edge area of the pane, as well as any coating-free edge area in coated panes, are preferably concealed by this masking print and thus visually concealed. The opaque screen print can be applied at any level of the laminated glass pane.
[0042] The invention further comprises a method for producing a windshield according to the invention, which comprises the following method steps: a) providing a first pane or a second pane, b) placing a thermoplastic intermediate layer comprising a first polymer film and a second polymer film on the first pane or the second pane, c) completing the layer stack with the second pane or first pane, d) laminating the layer stack comprising at least the first pane, the thermoplastic intermediate layer and the second pane to form the windshield.
[0043] The thermoplastic intermediate layer can be applied in step b) by applying the first polymer film and the second polymer film simultaneously or sequentially. The first polymer film and the second polymer film are cut before or after the first polymer film and the second polymer film are applied in step b), but in any case before step c). The first polymer film and / or the second polymer film can also be implemented in the form of multiple films, for example, two or more thermoplastic films. The features mentioned in the description of the windshield also apply to the process, and vice versa.If coatings, such as solar control coatings or heatable coatings, are to be applied to the surfaces of the first pane and the second pane facing the thermoplastic interlayer, the panes are preferably bonded to form a laminated glass after the coating has been applied. If the windshield includes coatings that are to be electrically contacted, the electrical contacting of the electrically conductive layers takes place via bus bars or other suitable electrical conductors before the laminated pane is laminated.
[0044] Any existing prints, such as opaque cover prints, are preferably applied using the screen printing process.
[0045] The first pane and the second pane are bonded to the windshield via the thermoplastic intermediate layer, preferably by lamination under the influence of heat, vacuum, and / or pressure. Known methods for producing a composite pane can be used. During lamination, the heated, flowable thermoplastic material flows, creating a stable composite.
[0046] For example, so-called autoclave processes can be carried out at an increased pressure of approximately 10 to 15 bar and temperatures of 130°C to 145°C for approximately 2 hours. Conventional vacuum bag or vacuum ring processes, for example, operate at approximately 200 mbar and temperatures of 80°C to 110°C. The first sheet, the thermoplastic intermediate layer, and the second sheet can also be pressed into a sheet in a calender between at least one pair of rollers. Systems of this type are known for the production of sheets and usually have at least one heating tunnel upstream of a pressing unit. The temperature during the pressing process can range, for example, from 40°C to 150°C. Combinations of calender and autoclave processes have proven particularly successful in practice. Alternatively, vacuum laminators can be used.These consist of one or more heatable and evacuatable chambers in which the 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.
[0047] The invention further comprises a motor vehicle comprising at least a body, at least one driver airbag and a windshield according to the invention, wherein the windshield is inserted into an opening in the body. The windshield has an upper edge, a lower edge opposite the upper edge and two opposite side edges. The upper edge refers to the edge which is intended to point upwards in the direction of the vehicle roof in the installed position. The upper edge is generally referred to as the roof edge or front roof edge. The lower edge refers to the edge which is intended to point downwards in the direction of the vehicle's hood in the installed position. The lower edge is generally referred to as the engine edge. The side edges of the windshield lie opposite one another and connect the lower edge to the upper edge.The side edges of the windshield border the body sections commonly referred to as A-pillars. In the case of continuous panoramic glazing, where the windshield encompasses part of the roof, the roof edge may be offset rearward into the roof area. The motor vehicle is preferably a passenger car.
[0048] The features disclosed with respect to the windshield according to the invention apply equally to the motor vehicle comprising this windshield.
[0049] All standards mentioned refer to the version valid on the date of filing.
[0050] The various embodiments of the invention can be implemented individually or in any combination. In particular, the features mentioned above and those to be explained below can be used not only in the specified combinations, but also in other combinations or on their own, without departing from the scope of the invention. Unless embodiments and / or their features are explicitly mentioned only as alternatives or are mutually exclusive.
[0051] The invention is described in more detail below with reference to the figures. It should be noted that various aspects are described, each of which can be used individually or in combination. This means that any aspect can be used with different embodiments of the invention, unless explicitly presented as a mere alternative.
[0052] The drawings are simplified, schematic representations and not to scale. The drawings do not limit the invention in any way.
[0053] They show:
[0054] Fig. 1 is a plan view of an embodiment of a windshield according to the invention and Fig. 2a-2d are sections of a cross section through the embodiment of a windshield according to the invention shown in Fig. 1.
[0055] Figure 1 shows a plan view of an embodiment of a windshield 10 according to the invention, while Figures 2a-d show a cross section through the windshield 10 shown in Figure
[0056] 1 shown embodiment along the section line C'-C according to Figure 1 as well as views of the cross section in the enlarged area Z.
[0057] The windshield 10 shown in Figures 1 and 2a-d comprises a first pane 1 and a second pane 2, which are connected to one another via a thermoplastic intermediate layer 3. The first pane 1 has an outside surface I and an interior surface II. The second pane has an outside surface III and an interior surface IV. In the installed state of the windshield, the outside surfaces I, III point towards the surroundings, while the interior surfaces II, IV are oriented towards the vehicle interior in the installed state. The interior surface II of the first pane 1 is connected to the outside surface III of the second pane via the thermoplastic intermediate layer 3.
[0058] 2. The thermoplastic intermediate layer 3 comprises at least a first polymer film 3.1 and a second polymer film 3.2. The windshield 10 has a roof edge D, an engine edge M opposite the roof edge, and two opposite side edges S that connect the engine edge M and the roof edge D to one another.
[0059] As can be seen from Figures 1 and 2a-d, the second polymer film 3.2 is arranged only in a second surface area B of the windshield 10, which, when the windshield 10 is installed in a motor vehicle, comprises the contact surface between the deployed vehicle airbag and the windshield 10. The remaining surface area of the windshield 10 is referred to as the first surface area A. In the first surface area A of the windshield 10, the thermoplastic intermediate layer 3 is formed by the first polymer film 3.1. The first pane 1 is, for example, a glass pane made of soda-lime glass with a thickness of 2.1 mm. The second pane 2 consists, for example, of soda-lime glass and has a thickness of 1.6 mm. The first polymer film 3.1 within the first surface area A consists, for example, of a PVB used standardly for such purposes and is 0.76 mm thick. The first polymer film 3.1 is a PVB film with a modulus of elasticity of less than 20 MPa, measured according to ASTM D882. Within the second surface region B, the thermoplastic intermediate layer 3 contains at least a second polymer film and can be single-layer or multi-layered, with Figures 2a-d showing preferred embodiments. The detailed structure in the second surface region B is shown in Figures 2b-d. Furthermore, the explanations in connection with Figures 1 and 2a apply accordingly.
[0060] According to Figure 2b, the thermoplastic intermediate layer 3 in the second surface area B consists of a single second polymer film 3.2. The second polymer film 3.2 is, for example, a 0.76 mm thick ionomer film with increased stiffness, such as is commercially available under the trade name SentryGlas®. The second polymer film 3.2 is an ionomer film with a modulus of elasticity greater than 300 MPa, measured according to ASTM D882. However, a stiffer PVB film, which is commercially available under the name Saflex®, DG41, can also be used as the second polymer film. In this case, the second polymer film 3.2 is a PVB film with a modulus of elasticity greater than 100 MPa, measured according to ASTM D882. Likewise, polymer films commercially available under the trade names trosifol® or Evalam® can be used as the second polymer film.1 in the first surface area A and the second polymer film 3.2 in the second surface area B have the same thickness.
[0061] In Figure 2c, the thermoplastic intermediate layer 3 in the second surface area B consists of a first polymer film 3.1 with a thickness of 0.38 mm and a second polymer film 3.2, also with a thickness of 0.38 mm. The first polymer film 3.1 is a PVB film with a modulus of elasticity of less than 20 MPa, while the second polymer film 3.2 is a PVB film with a modulus of elasticity of greater than 100 MPa, each measured according to ASTM D882.
[0062] According to Figure 2d, the thermoplastic intermediate layer 3 in the second surface area B consists of, in this order, a first polymer film 3.1 with a thickness of 0.38 mm, a second polymer film 3.2 with a thickness of 50 μm, and a first polymer film 3.1 also with a thickness of 0.38 mm. The first polymer films 3.1 are PVB films with a modulus of elasticity of less than 20 MPa, while the second polymer film 3.2 is a PET film with a modulus of elasticity of greater than 100 MPa, each measured according to the ASTM D882 standard. Initial tests by the inventors have shown that all embodiments increase accident safety due to less deformation of the windshield 10 in the second surface area B, even if one of the panes 1, 2 breaks. The improved rigidity of the windshield 10 after the pane breakage provides a greater counterforce to the deploying airbag, ensuring optimal deployment of the airbag.
[0063] List of reference symbols
[0064] 10 Windshield
[0065] 1 first slice
[0066] 2 second slice
[0067] 3 thermoplastic intermediate layer
[0068] 3.1 first polymer film
[0069] 3.2 second polymer film
[0070] A first surface area
[0071] B second surface area
[0072] X neckline
[0073] D roof edge
[0074] M engine edge
[0075] S side edges
[0076] I outer surface of the first pane 1
[0077] 11 Interior surface of the first pane 1
[0078] III outer surface of the second pane 2
[0079] IV Interior surface of the second pane 2
[0080] Z enlarged area displayed
[0081] CC' cutting line
Claims
Claims Windshield (10) with an engine edge (M), a roof edge (D) and two side edges (S) extending between them, comprising at least a first pane (1) with an outer surface (I) and an inner surface (II) and a second pane (2) with an outer surface (III) and an inner surface (IV), wherein the inner surface (II) of the first pane (1) and the outer surface (III) of the second pane (2) are connected to each other via a thermoplastic intermediate layer (3), and wherein - the thermoplastic intermediate layer (3) comprises at least a first polymer film (3.1) with a first stiffness and at least a second polymer film (3.2) with a second stiffness, - the second stiffness is higher than the first stiffness, - the windscreen (10) includes at least a second surface area (B) in which the thermoplastic intermediate layer (3) contains at least the second polymer film (3.2), - the windscreen (10) comprises at least one first surface area (A) in which the thermoplastic intermediate layer (3) does not comprise a second polymer film (3.2) and at least one first polymer film (3.1), - the second surface area (B) in the installed state of the windshield (10) in a motor vehicle includes at least the contact area between the deployed driver airbag of the motor vehicle and the windshield (10) and - the at least one second surface area (B) occupies less than 60% of the total area of the windshield (10). Windshield (10) according to claim 1, wherein the at least one second surface area (B) occupies less than 50%, preferably 20% to 40%, of the total area of the windshield (10). Windshield (10) according to claim 1 or 2, wherein the second surface area (B) is surrounded by a first surface area (A) and the first surface area (A) comprises exactly one first polymer film (3.1). Windscreen (10) according to claim 3, wherein the first polymer film (3.1) has a cutout (X) in at least a second surface area (B) and at least one second polymer film (3.2) is inserted into this cutout (X). Windscreen (10) according to claim 3 or 4, wherein the thermoplastic intermediate layer (3) in the first surface area (A) consists of one or more first polymer films (3.1). Windscreen (10) according to any one of claims 3 to 5, wherein the thickness of the thermoplastic intermediate layer (3) in the first surface area (A) differs by less than 10%, preferably by less than 5%, particularly preferably by less than 2%, from the thickness of the thermoplastic intermediate layer (3) in the second surface area (B). Windscreen (10) according to one of claims 1 to 6, wherein the thermoplastic intermediate layer (3) in the second surface area (B) consists of a second polymer film (3.2) or of a second polymer film (3.2) and a first polymer film (3.1) or consisting of, in this order, a first polymer film (3.1), a second polymer film (3.2), and a first polymer film (3.1). Windscreen (10) according to any one of claims 1 to 7, wherein the first polymer film (3.1) comprises polyvinyl butyral (PVB), polyurethane (PU), ionomers, and / or ethylene vinyl acetate (EVA), and the second polymer film (3.2) comprises polyvinyl butyral (PVB), polyethylene terephthalate (PET), polyurethane (PU), ionomers, and / or ethylene vinyl acetate (EVA). Windscreen (10) according to one of claims 1 to 8, wherein the first polymer film (3.1) is a PVB film with a modulus of elasticity of less than 20 MPa and the second polymer film (3.2) is a PVB film with a modulus of elasticity greater than 100 MPa or a PET film with a modulus of elasticity greater than 100 MPa, each measured according to standard ASTM D882.Windshield (10) according to any one of claims 1 to 9, wherein the first pane (1) and the second pane (2) comprise glass and each have a thickness of 0.8 mm to 2.5 mm, preferably 1.2 mm to 2.2 mm. Method for manufacturing a windshield (10) according to any one of claims 1 to 10, wherein at least. a) a first pane (1) or a second pane (2) is provided, b) a thermoplastic intermediate layer (3) comprising a first polymer film (3.1) and a second polymer film (3.2) is applied to the first pane (1) or the second pane (2), c) the layer stack is completed with the second pane (2) or the first pane (1), and d) the layer stack consisting of at least the first pane (1), thermoplastic intermediate layer (3), and second pane (2) is laminated to form a windshield (10). A method according to claim 11, wherein the first polymer film (3.1) and the second polymer film (3.2) are applied simultaneously or sequentially in step b). A motor vehicle comprising at least a body, at least one driver airbag, and a windshield (10) according to any one of claims 1 to 10, wherein the windshield (10) is inserted into an opening in the body.