Windshield with improved impact protection

Abstract

Windscreen (10) having a motor edge (M), a roof edge (D) and two side edges (S) extending therebetween, comprising at least an outer glass pane (1) made of glass having an outer side surface (I) and an inner space side surface (II) and an inner glass pane (2) made of glass having an outer side surface (III) and an inner space side surface (IV), wherein the inner space side surface (II) of the outer glass pane (1) and the outer side surface (III) of the inner glass pane (2) are connected to each other by a thermoplastic intermediate layer (3), and wherein - the windscreen (10) comprises at least one first sub-area (X) in which a transparent cover print (4) comprising enamel is applied on the outer glass pane (1) and / or the inner glass pane (2), - the first sub-area (X) is arranged along the motor edge (M) and extends from the motor edge (M) in the direction of the roof edge (D) of the windscreen (10), and - the windscreen (10) has in the first sub-area (X) at least partially a transmittance of at least 70% in the visible range of the spectrum.

Description

[0001] This invention relates to a windshield with improved impact protection, its manufacturing method, and its use.

[0002] Composite glass panels, comprising at least two glass panels and at least one polymer film bonded between the glass panels, have been widely used for decades in various technical fields, particularly in building glazing and the transportation manufacturing industry. The choice of materials and the dimensions of components depend on the requirements of the specific application, especially regarding the mechanical load-bearing capacity required for the finished glazing, taking into account the boundary conditions set by the frame and possible mounting components.

[0003] US 3,437552 A discloses a composite glass plate comprising two glass plates and a polyvinyl butyral (PVB) layer therebetween.

[0004] US 6,708,595 B1 discloses an armored composite vitreous glass plate for motor vehicles, comprising a stacked sequence of multiple glass plates and multiple adhesive intermediate layers therebetween.

[0005] DE 4013300 A1 discloses a windshield with a filter strip, wherein the filter strip attenuates light and heat radiation and includes a transparent coating of baked ink containing a colloidal distribution of a precious metal.

[0006] Particularly in the automotive industry, there is a trend towards using thinner and therefore lighter glass in composite glass panels in an effort to reduce weight and thus save fuel and electricity. These assembled glasses must still meet given mechanical requirements defined in relevant industry standards. This increases safety requirements not only for vehicle occupants but also for other road users such as pedestrians. In a head-on collision between a pedestrian and a car, the pedestrian is likely to hit the car's hood, with their head striking the windshield. This can cause serious to fatal injuries, especially if their head penetrates the windshield and hits other objects such as the dashboard.

[0007] Therefore, the object of the present invention is to provide an improved windshield that, on the one hand, provides greater accident safety for pedestrians, and on the other hand, ensures compliance with relevant standards for windshields in terms of stone impact resistance and transparency.

[0008] According to the invention, the objective is achieved by a windshield according to the invention.

[0009] The windshield according to the invention comprises at least an outer glass panel and an inner glass panel, which are connected to each other by means of a thermoplastic interlayer. Both glass panels are made of glass. The surrounding edges of the windshield have four parts, referred to as the engine edge, roof edge, and side edges based on the windshield's mounting position in a motor vehicle, wherein two opposing side edges are connected to the engine edge and roof edge. The outer glass panel has an outer surface I and an inner space side surface II. The inner glass panel has an outer surface III and an inner space side surface IV. In the installed state of the windshield in a motor vehicle, the outer surfaces of the glass panels face the vehicle environment, while the inner space side surfaces refer to the surfaces of the glass panels facing the vehicle's interior space. The inner space side surface II of the outer glass panel is connected to the outer surface III of the inner glass panel via the thermoplastic interlayer. The windshield has at least one first sub-region that extends adjacent to the windshield engine edge towards the roof edge. In the first sub-region, the outer glass panel and / or the inner glass panel have a transparent overlay printing comprising enamel. Here, the windshield has at least 70% transmittance in the first sub-region across the visible spectrum. The printed overlay protrudes at least partially into the A-field of view of the windshield according to ECE-R 43, Annex 3, § 9.1, a method for testing the transmittance of glass panels for motor vehicles. In the A-field of view, the windshield requires at least 70% transmittance across the visible spectrum.

[0010] The transparent overlay printing differs from the opaque overlay printing commonly used in the automotive industry in its transparent design. This means that, in the perspective direction through the windshield, objects can be identified within the area of ​​the transparent overlay printing through the glass. The windshield is therefore largely transparent with visible spectrum radiation in the first sub-region where the transparent overlay printing is applied.

[0011] The inventors have discovered that when an object impacts a windshield, the windshield exhibits improved fracture characteristics in a first sub-region. Here, the first sub-region is the area adjacent to the engine edge, where a pedestrian's head is more likely to land in an accident. It is known that enamel applied to glass reduces its strength. The inventors have utilized this generally undesirable effect to influence the fracture characteristics of the windshield. In this case, targeted weakening of the outer and / or inner glass panes of the windshield during a body impact causes early fracture. After one or two glass panes fracture, a significant amount of energy is absorbed through the extension of the thermoplastic interlayer and at least partial delamination in the fractured glass pane region. The thermoplastic interlayer is stretchable and therefore yields, resulting in a less abrupt head deceleration and a relatively small rate of deceleration. Sudden head deceleration, as seen in late-stage glass fracture, should be avoided. Windshields without a transparent overlay printing, not according to the invention, exhibit late-stage glass fracture upon head impact, where most of the impact's kinetic energy is dissipated through the bending of the glass, leading to a high rate of head deceleration. To quantify head impact, for example using… Head Injury Criteria (HIC) It assesses the severity of an impact by assessing the head's deceleration rate. A high deceleration rate is generally associated with a high HIC value, which in turn is associated with severe head injuries to pedestrians. Here, a low HIC value means a low risk of severe head injury. Defects in the form of low-strength areas in the glass are selectively introduced into the transparent overlay printing area. Typically, when tensile stress is applied to a defective area of ​​the glass, glass breakage usually begins there. Due to manufacturing reasons, a small number of statistically distributed defects can be found in vitreous glass sheets. However, due to the statistical distribution of such natural defects, their impact on breakage behavior cannot be predicted. In contrast to random defects in the glass, defects introduced by the transparent overlay printing in the first sub-region of the windshield according to the invention can be selectively placed in the first sub-region of the windshield as areas intended to cause early breakage. Thus, the windshield according to the invention also provides greater safety for pedestrians in traffic accidents involving pedestrians, because in a frontal collision, the severity of the head impact is reduced due to the early breakage of the windshield.

[0012] In the first sub-region, the windshield must have at least 70% transmittance over the visible range of the spectrum. Specifically, in the windshield's primary field of view (also known as Zone A), the transmittance over the visible range must be at least 70% to comply with legal requirements for windshields (ECE-R 43, Annex 3, § 9.1 Method for testing the transmittance of glass panes for motor vehicles). A 70% transmittance is required in the area of ​​the first sub-region that protrudes into the windshield's primary field of view; lower transmittance is sufficient in other areas.

[0013] The transmittance of the windshield in the first sub-region is influenced by, for example, the transparency of the enamel itself in the transparent overlay and by the application of the enamel to the entire surface or a portion thereof. In principle, the larger the area of ​​the enamel region of the transparent overlay, the greater the transparency of the enamel itself should be. To produce a transparent overlay with a low-transparency enamel, the enamel is used in a small area, so that the transparent overlay has the desired transparency as a whole. In this way, a transparent overlay can be obtained that does not interfere with the visual appearance when viewed through a glass plate. The enamel of the transparent overlay is preferably colorless and particularly preferably transparent or translucent, and the enamel particularly has a visible light transmittance of at least 20%, preferably at least 40%, and especially at least 50%.

[0014] A windshield provides a means of separating the interior space of a vehicle from the external environment. In other words, a windshield is a window glass fitted into or provided within a window opening in the vehicle body. The windshield is embedded in this body opening between the hood, the roof, and the A-pillars of the vehicle body. The edge of the windshield closest to the vehicle's engine area in its installed state is called the engine edge, and the edge opposite the engine edge is called the roof edge, oriented adjacent to the vehicle roof. The two edges of the windshield extending adjacent to the A-pillars (also called A-pillars) are called the side edges of the windshield, connecting the engine edge and the roof edge to each other. A first glass panel is the outer glass panel of the windshield, facing the external environment of the vehicle, while a second glass panel of the windshield forms the inner glass panel, oriented towards the interior space of the vehicle. Needless to say, the first glass panel, the second glass panel, and the thermoplastic interlayer have substantially the same external dimensions. The surface of each glass panel facing the external environment of the vehicle in its installed position is called the outer surface. The surface of each glass panel facing the interior space of the vehicle at its installation location is called the interior space side surface. The interior space side surface of the outer glass panel is connected to the outer surface of the inner glass panel via a thermoplastic interlayer. The outer surface of the outer glass panel is generally referred to as "Side I", the interior space side surface of the outer glass panel is referred to as "Side II", the outer surface of the inner glass panel is referred to as "Side III", and the interior space side surface of the inner glass panel is referred to as "Side IV".

[0015] The windshield according to the invention has a first surface area, referred to as a first sub-region. The first sub-region includes at least one area proportion of the windshield, but may also include the entire glass panel surface of the windshield. If the first sub-region includes an area smaller than the entire glass panel surface of the windshield, the surface area not included in the first sub-region is referred to as a second sub-region of the windshield. In this case, the second sub-region includes the area where no transparent overprint is applied. Multiple first and / or second sub-regions may also exist, wherein the first sub-regions include the transparent overprint, while the second sub-regions do not. In a preferred embodiment, the windshield has only one first sub-region and one second sub-region, which together cover the entire surface of the windshield.

[0016] The thermoplastic interlayer may include one or more additional films. These may be films with electro-switching capabilities or colored regions, for example. The thermoplastic interlayer may be constructed as a single layer or multiple layers. In one possible embodiment, the thermoplastic interlayer is implemented as a film laminate, for example, as a film laminate having three layers.

[0017] The first sub-region preferably occupies 10% to 100% of the total windshield area, more preferably 20% to 90%, and particularly preferably 30% to 70%. Experiments have shown that the aforementioned preferred area proportion of the first sub-region is sufficient to... In head impact experiments Achieve good security.

[0018] The first sub-region preferably extends at least partially from the engine edge of the windshield towards the roof edge of the windshield by an amount corresponding to 10% to 90%, preferably 20% to 70%, of the windshield height. The windshield height is determined here by measuring the shortest distance from the roof edge at a relevant location on the engine edge. Then, the amount by which the first sub-region extends in the direction of the roof edge is determined at the same location on the engine edge as the shortest distance between the engine edge and the upper edge of the first sub-region offset towards the roof edge, thus obtaining the height of the first sub-region along the engine edge at that location. This height of the first sub-region is related to the windshield height, each measured at the same location along the windshield, thus obtaining the relative amount by which the first sub-region extends from the engine edge towards the roof edge. The height to which the first sub-region extends is determined based on the vehicle geometry, wherein preferably, the area where a pedestrian's head is highly likely to hit in the event of an accident is located in the first sub-region. The first sub-region is positioned adjacent to the engine edge and extends at least partially from there to the aforementioned windshield height. Here, it is indicated in part that the first sub-region protrudes into the windshield along the engine edge towards the roof edge in at least one portion up to the mentioned height, but may have a smaller height in other portions. The upper edge of the first sub-region, that is, the edge portion of the first sub-region having the maximum distance from the engine edge of the windshield, preferably extends linearly or curvedly between the side edges of the windshield.

[0019] In a particularly preferred embodiment, the size of the first sub-region is chosen such that, in the installed state, the size of the first sub-region corresponds to at least 90% of the projected area of ​​the vehicle's dashboard on the windshield. Particularly preferably, the size of the first sub-region corresponds at least to the projected area of ​​the dashboard on the windshield. A common accident scenario involving pedestrians is that the pedestrian's head lands on the windshield in the area of ​​the dashboard. If the windshield is breached in this area, the pedestrian's head directly impacts the dashboard located behind it, thereby increasing the likelihood of serious injury. In this regard, it is advantageous to designate the area of ​​the windshield covered by the projection of the dashboard onto the glass in the installed state as the first sub-region, whereby the windshield breaks at an earlier stage. Therefore, the invention is preferably implemented as a motor vehicle including a windshield according to the invention, wherein the first sub-region of the windshield corresponds to at least 90%, preferably at least 100%, of the projected area of ​​the vehicle's dashboard on the windshield.

[0020] A transparent overlay is applied to the outer and / or inner glass panes. This selectively weakens one or both panes of the windshield, leading to early breakage. Early breakage of the windshield reduces the severity of the impact. After the glass breaks, a significant amount of energy is absorbed due to the extension of the thermoplastic interlayer and the partial delamination of the broken glass fragments. Due to the extension of the thermoplastic interlayer, the person's head is exposed to a relatively small rate of deceleration. In this case, the very sudden head deceleration that would occur in the case of late-breakage glass is avoided. The transparent overlay is preferably placed on the inner space side surface of the outer and / or inner glass panes. The windshield does not break directly from an impact on the outer surface, but rather from tensile stress generated within the glass, particularly on the inner space side surfaces of the outer and inner glass panes. This is especially true for semi-rigid objects such as the human head. Here, the windshield first breaks at the point of greatest tensile stress. If an impact occurs on the outer surface of the outer glass pane, the greatest tensile stress is generated on the inner space side surfaces of both the outer and inner glass panes. If the transparent overlay print is placed on one of these surfaces, the desired early cracking occurs there. Particularly preferably, the transparent overlay print is placed at least on the inner space side surface of the inner glass plate. On this surface, the highest tensile stress occurs, and it is also an easily accessible and printable glass plate surface.

[0021] The transparent overprint can be applied to the entire surface or a portion of the surface within a first sub-region. The transparent overprint is preferably applied to a portion of the surface, i.e., including a printed area and at least one unprinted area. The printed area is referred to herein as the printed area, while the at least one unprinted area is the non-printed area. If only one non-printed area exists, it extends as a continuous area between and surrounds the printed areas. Multiple non-printed areas may also exist, separated from each other by one or more printed areas. Applying a transparent overprint with both printed and non-printed areas to a portion of the surface is beneficial for improving the transparency of the glass and for better control of the breakage pattern. It has been proven that applying a transparent overprint to a portion of the surface is sufficient to induce the desired early breakage of the glass. Preferably, the printed areas are formed in a dotted, elliptical, cross-shaped, or rectangular pattern. In this way, the printed areas can be distributed in a particularly inconspicuous manner, thereby only slightly affecting the transparency of the windshield. Rounded corners or circular or elliptical printed areas have proven advantageous for ensuring the most accurate printing possible.

[0022] The printed area of ​​the transparent overlay preferably occupies 1% to 60% of the total area of ​​the second sub-region, particularly preferably 5% to 50%, and especially 10% to 40%. This proportion has been proven sufficient to... In head impact experimentsTo achieve the desired early breakage of the outer glass panel, the printed area is preferably formed with a regular or irregular pattern, through which the breakage pattern can be controlled according to the geometry of the windshield.

[0023] The printed areas preferably form regular or irregular patterns, wherein adjacent printed areas occupy an average spacing of 1 cm to 50 cm, preferably 2 cm to 30 cm, particularly preferably 3 cm to 15 cm, for example 5 cm to 10 cm. If no one or more other printed areas have a smaller spacing, then a printed area is adjacent to one or more other printed areas. In other words, adjacent printed areas are the closest printed areas to each other and are separated from each other by non-printed areas. This has proven advantageous, so that a head hitting the windshield in each case falls near a printed area in the first sub-region. The printed areas preferably form regular dot patterns, wherein adjacent dots have a spacing of 1 cm to 50 cm, preferably 2 cm to 30 cm, particularly preferably 3 cm to 15 cm, for example 5 cm to 10 cm. If no one or more other dots have a smaller spacing, then a dot is adjacent to one or more other dots. In other words, adjacent dots are the closest dots to each other and are separated from each other by non-printed areas. These dots are printed areas and are surrounded by continuous non-printed areas. This regular pattern is easy to apply, for example by screen printing, and is advantageous in ensuring reliable glass breakage at all locations within the first sub-region. Screen printing has proven to be particularly advantageous for applying the pattern according to the invention.

[0024] The diameter of the printed area is preferably between 0.1 mm and 10 mm. This allows for reliable glass breakage, while simultaneously keeping the printed area small to save costs and avoid adverse optical effects. Printed areas with diameters of 0.2 mm to 5.0 mm, particularly 0.2 mm to 3.0 mm, such as 0.3 mm to 1.0 mm, have proven to be particularly preferred. Printed areas of this size are visually inconspicuous to vehicle drivers and, in the inventors' experiments, resulted in the desired early breakage of the glass.

[0025] In one possible implementation, the area ratio of the printed area within the first sub-region decreases from the engine edge towards the roof edge. Therefore, the area ratio of the printed area per unit area adjacent to the upper edge of the first sub-region is smaller than that adjacent to the engine edge. In this way, a gradual transition can be achieved between the first sub-region and its adjacent unprinted second sub-region.

[0026] The transparent overlay printing is preferably a printed enamel containing SiO2, particularly preferably SiO2, Bi2O3, and ZnO. Enamels containing these components are known and are produced, for example, by baking a printing paste onto a glass surface. Printing pastes suitable for automotive and building glazing are commercially available and typically contain solvents and pigments in addition to the aforementioned components. The solvents evaporate during baking and are no longer present in the resulting enamel. From an aesthetic point of view, the pigments contained in commercially available printing pastes are used to color the glass sheet. Furthermore, black-colored printing pastes are used in the automotive field for opaque overlay printing in the edge areas along the surrounding edges, in the case of windshields and rear windows. These known printing pastes, with their basic composition, are suitable for manufacturing transparent overlay printings according to the invention; however, it is preferable to omit all pigments for the application according to the invention.

[0027] Within the printing area, the overprint applied to the first sub-region causes a reduction in the strength of the glass in contact with the overprint. When the printing paste is baked, pores are formed in the resulting enamel, which transfer defect sites corresponding to their respective pores to the underlying glass, resulting in the desired reduction in strength. Particularly advantageous fracture behavior can be determined when the printed enamel has pores with a size of 0.5 μm to 5 μm, particularly preferably 2.0 μm to 4.0 μm. Methods for determining the pore size are known to those skilled in the art. For example, electron microscopy can be used to determine the pore size. The FIB method (FIB is...) is preferred. Gather (Pyroion beam). Currently, with the help of Dual-beam FIB nanotomography This technique determines the aperture size. It enables the reconstruction and analysis of three-dimensional material volumes with very high resolution.

[0028] The portion of the first sub-region that has the maximum distance from the engine edge along the first sub-region is called the upper edge of the first sub-region. Here, the edge of the first sub-region is the line surrounding the first sub-region with the printed material. The upper edge of the first sub-region preferably extends between the side edges of the windshield, wherein the upper edge may, but does not necessarily, terminate at the side edges of the windshield. This means that the upper edge may intersect with the respective side edges at one or both side edges of the windshield.

[0029] In principle, the first sub-region can have any arbitrary shape and preferably has a rectangular or rounded rectangular or semi-circular or semi-elliptical shape, each adjacent to the engine edge of the windshield. Other shapes are also suitable depending on the geometry of the windshield.

[0030] In a preferred embodiment, the upper edge of the first sub-region extends linearly between the side edges and terminates at the side edge of the windshield. For a linear upper edge, a horizontal orientation has proven advantageous in achieving the desired strength reduction uniformly across all areas along the engine edge in the vehicle. In another preferred embodiment, the upper edge of the first sub-region has a curved orientation. This upper edge may terminate in the area of ​​the side edge, or it may extend toward a corner area and terminate directly in the corner area or at the portion of the engine edge adjacent to the corner area. This produces a semi-circular or semi-elliptical geometry for the first sub-region.

[0031] The thermoplastic interlayer preferably comprises polyvinyl butyral (PVB), polyurethane (PU), ionomer, and / or ethylene vinyl acetate (EVA), with PVB being particularly preferred. These materials have proven to be especially suitable for reliable bonding of glass sheets to each other.

[0032] The thickness of the thermoplastic interlayer is preferably 300 μm to 1000 μm, particularly preferably 500 μm to 900 μm, and especially 650 μm to 850 μm.

[0033] The outer and inner glass panes are made of glass, preferably soda-lime glass, as is common for window glass. However, the glass panes can also be made of other types of glass, such as quartz glass, borosilicate glass, or aluminosilicate glass.

[0034] The outer and inner glass panels can be independently constructed from non-prestressed, partially prestressed, or prestressed glass. If the outer and / or inner glass panels are required to be prestressed, this can be thermal prestressed or chemically prestressed.

[0035] The thicknesses of the outer and inner glass panels are preferably 0.8 mm to 2.5 mm, particularly preferably 1.2 mm to 2.2 mm. The thickness of the outer glass panel is typically 1.0 mm to 2.5 mm. The thickness of the inner glass panel is preferably 0.8 mm to 2.1 mm. The thickness of the outer glass panel is preferably greater than that of the inner glass panel. For example, the outer glass panel can be 2.1 mm thick and the inner glass panel 1.1 mm thick, or the outer glass panel can be 1.8 mm thick and the inner glass panel 1.4 mm thick, or the outer glass panel can be 1.6 mm thick and the inner glass panel 1.1 mm thick, or the outer glass panel can be 1.6 mm thick and the inner glass panel 0.7 mm thick, or the outer glass panel can be 1.4 mm thick and the inner glass panel 1.1 mm thick.

[0036] The inner glass pane, outer glass pane, and thermoplastic interlayer can be transparent and colorless, but can also be tinted or colored. The hue of the outer glass pane, inner glass pane, and thermoplastic interlayer is selected depending on the desired application of the composite glass pane. Windshields are desired to have high transmittance in the visible light range of the spectrum, and dark hues of the components are avoided. In one embodiment of a windshield for a motor vehicle, the total transmittance through the windshield is greater than 70%, based on light source type A. The term total transmittance refers to the method for testing the light transmittance of a motor vehicle glass pane as determined by ECE-R 43, Annex 3, § 9.1.

[0037] The windshield according to the invention is preferably curved in one or more spatial directions, as is common for windshields of motor vehicles, wherein a typical radius of curvature is from about 10 cm to about 40 m. However, the windshield can also be flat, for example, when intended for use as a glass panel of a bus, train, or tractor.

[0038] The inner glass plate, outer glass plate and / or thermoplastic interlayer may have additional suitable coatings known per se, such as anti-reflective coatings, non-stick coatings, scratch-resistant coatings, photocatalytic coatings, or sun-protective coatings or low-E coatings.

[0039] Automotive glass, particularly windshields, rear windows, and sunroofs, often features a surrounding perimeter covering printed with opaque enamel. This covering is specifically designed to protect the adhesives used to mount the glass panels from UV radiation and to visually conceal it. Preferably, at least the outer glass panel has this opaque perimeter covering; more preferably, both the outer and inner glass panels are printed to prevent visibility from the sides. The opaque covering is applied, for example, by screen printing, which defines the field of view of the glass panel or forms its outer edge. Electrical conductors that may be located in the edge areas of the glass panel, and, in the case of coated glass panels, optionally uncoated edge areas, are preferably shielded by this covering and thus optically masked. The opaque screen print can be placed in any plane of the windshield.

[0040] The present invention also includes a method for manufacturing a windshield according to the invention, comprising the following method steps: a) Provide an outer glass panel or an inner glass panel. b) Place a thermoplastic interlayer on the outer or inner glass plate. c) Stacking with an inner or outer glass plate enclosing layer having a transparent overlay of printed material, and d) Laminating layers consisting of at least an outer glass pane, a thermoplastic interlayer, and an inner glass pane into a windshield. A transparent overlay printed material is placed on the outer glass plate and / or the inner glass plate.

[0041] Preferably, the transparent overlay print is applied to the outer and / or inner glass plates prior to step a). Particularly preferably, the transparent overlay print is applied by screen printing and baked prior to step a). Screen printing is known to those skilled in the art. In the case of a transparent overlay print applied by screen printing, a reduction in intensity in particularly advantageous printing areas can be observed.

[0042] Thermoplastic interlayers can also be applied in the form of multiple films, such as two or more thermoplastic films.

[0043] If a coating, such as a sun-protective coating or a heat-resistant coating, is to be applied to the surfaces of the first and second glass plates facing the thermoplastic interlayer, it is preferable to join the glass plates into a composite glass after the coating is applied. If the windshield includes a coating that requires electrical contact, the conductive layer is made into electrical contact via a busbar or other suitable electrical conductor before the composite glass plates are laminated.

[0044] The opaque overlay printing that may be applied to the edge area of ​​the windshield is preferably applied by screen printing. If the opaque overlay printing and the transparent overlay printing are to be applied to the same glass surface, they are preferably applied sequentially.

[0045] The outer and inner glass panels are joined to form a windshield via a thermoplastic interlayer, preferably by lamination under heat, vacuum, and / or pressure. Methods known per se for manufacturing composite glass panels can be used. During lamination, heated, flowable thermoplastic material flows to form a stable composite.

[0046] The so-called autoclave method can, for example, be carried out for about 2 hours at a pressure of about 10 to 15 bar and a temperature of 130°C to 145°C. Vacuum bag or vacuum ring methods, known per se, operate, for example, at about 200 mbar and 80°C to 110°C. The outer glass sheet, thermoplastic intermediate layer, and inner glass sheet can also be pressed into a glass sheet in a calender between at least one pair of rollers. This type of equipment is known for manufacturing glass sheets and typically has at least one heating passage before the press. The temperature during the pressing process is, for example, 40°C to 150°C. In practice, the combination of the calender method and the autoclave method has proven particularly useful. Alternatively, a vacuum laminator can be used. These consist of one or more heated and vacuum-ejectable chambers in which the glass sheet is laminated, for example, over about 60 minutes, at a pressure of 0.01 mbar to 800 mbar and a temperature of 80°C to 170°C.

[0047] The invention also includes the use of the windshield according to the invention in motor vehicles, particularly preferably in passenger cars. The invention can also be used in continuous panoramic glass panels, wherein the windshield also includes a sub-region of the roof.

[0048] All standards mentioned refer to the version that was in effect on the application date.

[0049] Various embodiments of the present invention can be implemented individually or in any combination. In particular, without departing from the scope of the invention, the features mentioned above and explained below can be used not only in the given combinations, but also in other combinations or individually. Unless the exemplary embodiments and / or their features are explicitly mentioned as alternatives or mutually exclusive.

[0050] The invention will now be presented in more detail with reference to the accompanying drawings. It should be noted that different aspects are described, which can be used individually or in combination. That is, each aspect can be used with different embodiments of the invention, unless explicitly stated as a purely alternative.

[0051] The accompanying drawings are simplified schematic illustrations and are not drawn to scale. The drawings do not limit the invention in any way.

[0052] in: Figure 1a Figure b shows a plan view of one embodiment of the windshield according to the present invention. Figure 2 A segment of a cross-section through the windshield of the embodiment shown in FIG1 according to the invention is shown, and Figure 3 A sample with a transparent overprint consisting of three dot-printed areas is shown. This sample was used to study the flexural fracture strength of glass with an enamel print.

[0053] Figure 1a Figure b shows a plan view of one embodiment of the windshield 10 according to the present invention, while Figure 2 A segment of the cross section along section line C'-C of Figure 1 is shown, passing through the embodiment shown in Figure 1. Figure 1b It shows Figure 1a An enlarged view of region Z of the windshield according to the present invention.

[0054] Figure 1aThe windshield 10 shown in Figures 1, 2, and 3 includes an outer glass panel 1 and an inner glass panel 2, which are connected to each other by a thermoplastic interlayer 3. The outer glass panel 1 has an outer surface I and an inner space side surface II. The inner glass panel 2 has an outer surface III and an inner space side surface IV. In the installed state of the windshield 10, the outer surfaces I and III point towards the environment, while the inner space side surfaces II and IV are oriented towards the interior space of the vehicle. The inner space side surface II of the outer glass panel 1 is connected to the outer surface III of the inner glass panel 2 via the thermoplastic interlayer 3. The windshield 10 has a roof edge D, an engine edge M opposite to the roof edge, and two opposing side edges S connecting the engine edge M and the roof edge D. The windshield 10 has a first sub-region X and a second sub-region Y, wherein the first sub-region X is adjacent to the engine edge M.

[0055] As from Figure 1a and 2 As can be seen, the transparent overlay printing 4 is arranged in the first sub-region X of the windshield 10. The remaining surface area of ​​the windshield 10 is referred to as the second sub-region Y, and is completely devoid of this transparent overlay printing 4. The outer glass panel 1 is, for example, a vitreous glass panel made of soda-lime glass with a thickness of 2.1 mm. The inner glass panel 2 is, for example, made of soda-lime glass and has a thickness of 1.6 mm.

[0056] The first sub-region X has an upper edge 5, which is offset from the engine edge M towards the roof edge D. The upper edge 5 of the first sub-region X extends between the side edges K, wherein a transparent overlay print 4 is applied between the upper edge 5 of the first sub-region X and the engine edge M. Currently, the transparent overlay print 4 is arranged on the inner space side surface IV of the inner glass panel 2. It has been confirmed that this is effective for... In head impact experiments Achieving early breakage of the windshield 10 is particularly advantageous. If, as Figure 2 As shown, in addition to this, a transparent overlay print 4 can be arranged on the inner space side surface II of the outer glass plate 1 to achieve further improved results. The transparent overlay print 4 on the inner glass plate 2 and the outer glass plate 1 has dot-printed areas 4.1, which are surrounded by continuous non-printed areas 4.2.

[0057] The inventors have conducted experiments that experimentally confirm the targeted weakening of the vitreous glass plate in the area of ​​the transparent overprint according to the invention. For this purpose, the inventors conducted experiments using float glass plates with a thickness of 1.6 mm and dimensions of 1100 mm × 500 mm. A series of such samples were printed with an overprint 4 consisting of three enamel dots as the printing area 4.1, wherein the size of the dots was varied. Here, the overprint 4 was placed on the so-called fire side of the float glass plate. Glass manufactured using the float glass process has different surface properties and stresses on opposite surfaces of the float glass plate. Here, there is a distinction between the so-called bath side (which refers to the glass surface in contact with the tin bath) and the so-called fire side (which refers to the remaining opposite glass surface) of the float glass plate. Figure 3 The image shows the location of the dotted printing area 4.1 on the fire side of the sample. Figure 3 The sample shown is a glass plate 6 made of float glass. The sample was printed using a screen printing paste, which produces enamel in the printed area after the printed paste is baked.

[0058] The samples were subjected to flexural fracture strength tests according to DIN EN 1288-5, with the flexural fracture strength studied using the Weibull distribution. Table 1 shows the average characteristic Weibull strength determined here for samples 1 to 5 with a variable-sized printed area on the fire side of the sample, compared with the flexural fracture strength of two untreated control samples on the fire side (control sample V1) and bath side (control sample V2). The control samples differed from samples 1 to 5 only in that they did not have a transparent overprint. Table 1 also shows the number of samples studied for each and the shape parameter m of the Weibull distribution. Weibull distributions with a shape parameter m greater than 1 were used to study fatigue and wear damage, and also reflect the current fracture scenario of the glass plate.

[0059] Table 1 As can be seen in Table 1, a significant reduction in flexural fracture strength was observed in all samples compared to the control samples. This improvement can also be expected when a pedestrian impacts the first sub-region X, which has the printed area 4. The printed areas with a diameter of 0.5 mm have proven particularly advantageous in order to make them as visually inconspicuous as possible while ensuring high transmittance of the glass plate.

[0060] List of reference numerals 10 Windshield 1. Outer glass panel 2. Inner glass plate 3. Thermoplastic interlayer 4. Transparent overlay printing 4.1 Printing Area 4.2 Non-printing areas 5. The upper edge of the first subregion X 6. Glass plate, sample X First Subregion Y Second Subregion D. Roof edge M engine edge S side edge Z zooms in to show the segment CC' section line I. Outer surface of outer glass plate 1 II. Internal space side surface of outer glass panel 1 III. Outer surface of inner glass plate 2 IV. Inner glass plate 2 internal space side surface

Claims

1. A windshield (10) having an engine edge (M), a roof edge (D), and two side edges (S) extending therebetween, comprising at least an outer glass panel (1) made of glass having an outer surface (I) and an inner space side surface (II) and an inner glass panel (2) made of glass having an outer surface (III) and an inner space side surface (IV), wherein the inner space side surface (II) of the outer glass panel (1) and the outer surface (III) of the inner glass panel (2) are connected to each other by a thermoplastic interlayer (3), and wherein - The windshield (10) includes at least one first sub-region (X), in which a transparent overlay print (4) comprising enamel is applied to the outer glass panel (1) and / or the inner glass panel (2). - The first sub-region (X) is arranged along the engine edge (M) and extends from the engine edge (M) toward the roof edge (D) of the windshield (10). - A first sub-region (X) with a transparent overlay print protrudes at least partially into the field of view A of the windshield (10) according to ECE-R 43, and - The windshield (10) has a transmittance of at least 70% in the visible range of the spectrum in at least the area of ​​the first sub-region (X) that protrudes into the main field of view of the windshield. The transparent overlay printing (4) comprises a printed enamel containing SiO2, which is produced by baking a printing paste onto a glass surface and has a porous structure with pore sizes ranging from 0.5 μm to 5 μm. The first sub-region (X) occupies 10% to 100% of the total area of ​​the windshield (10).

2. The windshield (10) according to claim 1, wherein the first sub-region (X) occupies 20% to 90% of the total area of ​​the windshield (10).

3. The windshield (10) according to claim 2, wherein the first sub-region (X) occupies 30% to 70% of the total area of ​​the windshield (10).

4. The windshield (10) according to any one of claims 1 to 3, wherein the first sub-region (X) extends at least partially from the engine edge (M) of the windshield toward the roof edge (D) of the windshield (10) by an amount corresponding to 10% to 90% of the height of the windshield (10).

5. The windshield (10) according to claim 4, wherein the first sub-region (X) extends at least partially from the engine edge (M) of the windshield toward the roof edge (D) of the windshield (10) by an amount corresponding to 20% to 70% of the height of the windshield (10).

6. The windshield (10) according to any one of claims 1 to 3, wherein the transparent overlay print (4) is colorless.

7. The windshield (10) according to claim 6, wherein the transparent overlay print (4) is transparent or translucent.

8. The windshield (10) according to claim 6, wherein the transparent overlay print (4) has a visible light transmittance of at least 20%.

9. The windshield (10) according to claim 8, wherein the transparent overlay print (4) has a visible light transmittance of at least 40%.

10. The windshield (10) according to claim 8, wherein the transparent overlay print (4) has a visible light transmittance of at least 50%.

11. The windshield (10) according to any one of claims 1 to 3, wherein the transparent overlay print (4) is disposed on the inner space side surface (II) of the outer glass panel (1) and / or on the inner space side surface (IV) of the inner glass panel (2).

12. The windshield (10) according to any one of claims 1 to 3, wherein the transparent overlay print (4) comprises a printed area (4.1) and at least one non-printed area (4.2).

13. The windshield (10) according to claim 12, wherein the printed area (4.1) is formed in a circular, elliptical, cross-shaped or rectangular shape and is surrounded by the at least one non-printed area (4.2).

14. The windshield (10) according to claim 12, wherein the printed area (4.1) occupies 1% to 60% of the total area of ​​the first sub-region (X) and forms a regular or irregular pattern.

15. The windshield (10) according to claim 12, wherein the printed areas (4.1) form regular or irregular patterns and adjacent printed areas (4.1) occupy an average spacing of 1 cm to 50 cm.

16. The windshield (10) according to claim 15, wherein the adjacent printed areas (4.1) occupy an average spacing of 2 cm to 30 cm.

17. The windshield (10) according to claim 15, wherein the printed area (4.1) forms a regular dot pattern, wherein adjacent dots are spaced 1 cm to 50 cm apart.

18. The windshield (10) according to claim 17, wherein adjacent points are spaced 2 cm to 30 cm apart.

19. The windshield (10) according to any one of claims 1 to 3, wherein the transparent overlay printing (4) comprises a printed enamel containing SiO2, Bi2O3 and ZnO.

20. The windshield (10) according to any one of claims 1 to 3, wherein, The printed enamel has a porous structure with pore sizes ranging from 2.0 μm to 4.0 μm.

21. The windshield (10) according to any one of claims 1 to 3, wherein the thermoplastic interlayer (3) comprises polyvinyl butyral (PVB), polyurethane (PU), ionomer and / or ethylene vinyl acetate (EVA).

22. The windshield (10) according to any one of claims 1 to 3, wherein the first glass plate (1) and the second glass plate (2) each have a thickness of 0.8 mm to 2.5 mm.

23. The windshield (10) according to claim 22, wherein the first glass plate (1) and the second glass plate (2) each have a thickness of 1.2 mm to 2.2 mm.

24. A method for manufacturing a windshield (10) according to any one of claims 1 to 23, wherein at least a) Provide an outer glass panel (1) or an inner glass panel (2), b) Place the thermoplastic interlayer (3) on the outer glass plate (1) or the inner glass plate (2), c) Stacking with inner glass plate (2) or outer glass plate (1) as a sealing layer, and d) The layers consisting of at least an outer glass panel (1), a thermoplastic intermediate layer (3), and an inner glass panel (2) are stacked and laminated to form a windshield (10). The transparent overprinted article (4) is placed on the outer glass plate (1) and / or the inner glass plate (2).

25. The method according to claim 24, wherein the transparent overlay print (4) is applied to the inner space side surface (II) of the outer glass plate (1) and / or to the inner space side surface (IV) of the inner glass plate (2) prior to step a).

26. The method of claim 25, wherein the transparent overlay print (4) is applied by screen printing and the transparent overlay print (4) is baked prior to step a).

27. Use of the windshield (10) according to any one of claims 1 to 23 in a motor vehicle.

28. Use of the windshield (10) according to any one of claims 1 to 23 in a passenger vehicle.

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