Composite pane consisting of a polymer pane and a glass pane

Description

[0001] The invention relates to a composite pane made of a polymer pane and a glass pane, a method for its production and the use of a thin glass pane in such a composite pane.

[0002] The automotive industry is currently striving to reduce vehicle weight, which is particularly associated with reduced fuel consumption. One factor that contributes significantly to vehicle weight and therefore offers significant savings potential is glazing. Conventional vehicle glazing is made of glass panes, usually as toughened safety glass (TSG) or laminated safety glass (LSG). Toughened safety glass is a single pane of glass that is tempered to influence the stability and size of the fragments when the pane breaks. Laminated safety glass is a composite pane made of two, usually non-tempered, glass panes bonded together via a thermoplastic interlayer.

[0003] One approach to reducing the weight of vehicle glazing is the use of plastic panes instead of glass. However, plastic panes have several disadvantages compared to glass, particularly significantly lower scratch resistance, so replacing significant parts of vehicle glazing with plastic panes has not yet been feasible.

[0004] To increase scratch resistance, DE4415878A1 proposes bonding the plastic pane to a thin glass pane using a silicone adhesive.

[0005] Further prior art can be found in US3525658A, DE102012210906A1, DE202010008729U1, US4201828A, EP2705951A1, WO2017 / 196171A1, DE 102012009788A1 and EP 0669205 A1.

[0006] The present invention is based on the object of providing a further improved vehicle window which is lightweight and at the same time highly stable and scratch-resistant, as well as a method for its production.

[0007] The object of the present invention is achieved by a composite pane for vehicles according to claim 1. Preferred embodiments are evident from the subclaims.

[0008] The composite pane for vehicles according to the invention comprises a polymer pane (plastic pane) and a glass pane bonded to the polymer pane.

[0009] The laminated glass pane according to the invention is intended to separate the interior from the exterior in a window opening of a vehicle. The pane of the laminated glass facing the interior is referred to as the inner pane. The pane facing the exterior is referred to as the outer pane.

[0010] The great advantage of the invention lies in the combination of a polymer pane with a very thin glass pane. The polymer pane, which generally makes up the largest part of the thickness of the composite pane, makes the composite pane lightweight. The pane can therefore advantageously contribute to reducing the overall weight of the vehicle. The glass pane is very thin and therefore only leads to a slight increase in the weight of the pane. Nevertheless, the glass pane achieves a high level of stability and, in particular, scratch resistance of the pane. The glass pane also improves the acoustic properties of the pane, thus reducing the noise penetrating the pane, which is often described as a disadvantage of plastic panes compared to glass panes.

[0011] The glass pane is chemically tempered. Tempering can give the glass pane exceptional fracture stability and scratch resistance. For a very thin glass pane, as envisaged in the invention, chemical tempering is more suitable than thermal tempering. Since thermal tempering is based on a temperature difference between a surface zone and a core zone, thermal tempering requires a minimum thickness of the glass pane. Sufficient stresses can typically be achieved with commercially available thermal tempering devices for glass thicknesses of approximately 2.5 mm and above. For thinner glass thicknesses, the generally required tempering values ​​cannot usually be achieved (see, for example, ECE Regulation 43).In chemical tempering, the chemical composition of the glass is changed at the surface through ion exchange, with the ion exchange being limited to a surface zone by diffusion. Chemical tempering is therefore particularly suitable for thin panes.

[0012] Chemical tempering is also commonly referred to as chemical annealing, chemical hardening, or chemical strengthening. Chemically toughened glass panes for the automotive sector are known, for example, from DE1946358 and GB1339980.

[0013] The stability of the glass pane can be improved by suitable values ​​and local distributions of the stresses, which in the case of chemical toughening are generated by the incorporation of ions during chemical toughening.

[0014] In an advantageous embodiment, the glass pane has a surface compressive stress of greater than 100 MPa, preferably greater than 250 MPa and particularly preferably greater than 350 MPa.

[0015] The compressive stress depth of the glass pane is preferably at least one-tenth of the thickness of the glass pane, preferably at least one-sixth of the thickness of the glass pane, for example approximately one-fifth of the thickness of the glass pane. This is advantageous with regard to the breaking strength of the pane. With sufficient pane thickness, the compressive stress depth of the glass pane is preferably greater than 50 µm, particularly preferably greater than 100 µm. For the purposes of the invention, compressive stress depth refers to the depth, measured from the surface of the pane, to which the pane withstands compressive stresses of a magnitude greater than 0 MPa.

[0016] The glass pane has a thickness of less than or equal to 1 mm. Panes of this thickness are lightweight yet offer high stability and scratch resistance. The glass pane particularly preferably has a thickness of 0.1 mm to 1 mm, even more preferably 0.2 to 0.8 mm, and especially 0.4 to 0.7 mm. This achieves particularly good results in terms of low weight, high stability, and scratch resistance.

[0017] The polymeric pane has a thickness of 1.5 mm to 10 mm, particularly preferably 2 mm to 5 mm, and most preferably 2.5 mm to 4 mm, especially 3 mm to 4 mm. With a polymeric pane of this thickness, the pane according to the invention has sufficiently high stability to be used as a vehicle window.

[0018] The polymeric pane contains at least polycarbonate (PC), polymethyl methacrylate (PMMA) or copolymers or mixtures or derivatives thereof, particularly preferably polycarbonate or derivatives thereof.

[0019] The polymeric pane and the glass pane are bonded together via a thermoplastic intermediate layer. The thermoplastic intermediate layer can, for example, contain at least polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), polyurethane (PU), or mixtures or copolymers or derivatives thereof. In a preferred embodiment, the intermediate layer contains polyurethane or derivatives thereof. Surprisingly, these materials have been found to be particularly suitable for the intermediate layer for laminating the composite pane. Compared to other thermoplastic materials, particularly PVB, which is widely used for composite panes, they cause little diffusion between the polymeric pane and the intermediate layer during the lamination process. Such diffusion can lead, in particular, to impaired optical properties and impaired adhesion properties, which should be avoided for window panes.

[0020] The thickness of the thermoplastic intermediate layer is preferably 0.2 mm to 1 mm, particularly preferably 0.3 mm to 0.9 mm, for example 0.38 mm, 0.76 mm, or 0.86 mm. The thermoplastic intermediate layer is formed by a single or multiple thermoplastic films.

[0021] In a particularly advantageous embodiment, the thermoplastic intermediate layer has a noise-reducing effect. This advantageously further reduces the transmission of noise into the vehicle interior. Vehicle occupants are thus less disturbed by ambient noise and driving noise. This effect can be achieved by a multi-layer, for example, three-layer intermediate layer, with the inner layer exhibiting greater plasticity or elasticity than the surrounding outer layers, for example, due to a higher proportion of plasticizers.

[0022] In a preferred embodiment of the invention, the glass pane is the outer pane of the composite pane. Since damaging influences, particularly from the external environment, impact vehicle windows, this arrangement is particularly advantageous for increasing the stability of the pane.

[0023] In the invention, the opposite surfaces of the glass pane and the polymer pane form the outer surfaces of the composite pane. The composite pane consists of the polymer pane, the glass pane, and the thermoplastic interlayer between the panes. These components can also be coated. One example of such a coating is a scratch-resistant coating on the outer surface of the polymer pane.

[0024] In an alternative embodiment, which is not part of the invention, the surface of the polymeric pane facing away from the (first) glass pane according to the invention is bonded to a second glass pane. Both surfaces of the polymeric pane are thus each bonded to a glass pane according to the invention. In this way, both surfaces of the polymeric pane are protected from damage. The second glass pane preferably has a thickness of less than or equal to 1 mm, particularly preferably from 0.1 mm to 1 mm, very particularly preferably from 0.2 to 0.8 mm and in particular from 0.4 mm to 0.7 mm. The second glass pane is preferably also chemically tempered.

[0025] The glass pane can, in principle, have any chemical composition known to the person skilled in the art. For example, the glass pane can contain or consist of soda-lime glass or borosilicate glass. The glass pane must, of course, be suitable for chemical tempering and, in particular, contain a suitable proportion of alkali elements, preferably sodium. The glass pane preferably contains between 1% and 20% by weight of sodium oxide (Na2O). The glass pane can, for example, contain from 40 wt% to 90 wt% silicon oxide (SiO 2 ), from 0.5 wt% to 10 wt% aluminum oxide (Al 2 O 3 ), from 1 wt% to 20 wt% sodium oxide (Na 2 O), from 0.1 wt% to 15 wt% potassium oxide (K 2 O), from 0 wt% to 10 wt% magnesium oxide (MgO), from 0 wt% to 10 wt% calcium oxide (CaO), and from 0 wt% to 15 wt% boron oxide (B 2 O 3 ). The glass pane can also contain other components and impurities.

[0026] However, it has surprisingly been found that certain chemical compositions of the first pane are particularly suitable for chemical tempering. This is reflected in a high speed of the diffusion process, which leads to an advantageously short time expenditure for the tempering process, and large temper depths (compressive stress depths), which result in stable and fracture-resistant glasses. These compositions are preferred within the meaning of the invention.

[0027] The glass pane advantageously contains an aluminosilicate glass. The first pane preferably contains from 50 wt% to 85 wt% silicon oxide (SiO 2 ), from 3 wt% to 10 wt% aluminum oxide (Al 2 O 3 ), from 8 wt% to 18 wt% sodium oxide (Na 2 O), from 5 wt% to 15 wt% potassium oxide (K 2 O), from 4 wt% to 14 wt% magnesium oxide (MgO), from 0 wt% to 10 wt% calcium oxide (CaO), and from 0 wt% to 15 wt% boron oxide (B 2 O 3 ). The glass pane may also contain other components and impurities.

[0028] The glass pane particularly preferably contains at least from 55 wt% to 72 wt% silicon oxide (SiO 2 ), from 5 wt% to 10 wt% aluminum oxide (Al 2 O 3 ), from 10 wt% to 15 wt% sodium oxide (Na 2 O), from 7 wt% to 12 wt% potassium oxide (K 2 O), and from 6 wt% to 11 wt% magnesium oxide (MgO). The glass pane may also contain other components and impurities.

[0029] The glass pane most preferably contains at least 57 wt% to 65 wt% silicon oxide (SiO 2 ), 7 wt% to 9 wt% aluminum oxide (Al 2 O 3 ), 12 wt% to 14 wt% sodium oxide (Na 2 O), 8.5 wt% to 10.5 wt% potassium oxide (K 2 O), and 7.5 wt% to 9.5 wt% magnesium oxide (MgO). The glass pane may also contain other components and impurities.

[0030] The glass pane, the polymer pane and / or the interlayer can be clear and colorless, but can also be tinted or colored.

[0031] The composite pane according to the invention can be flat. Flat vehicle panes are particularly common in large-area glazing on buses, trains, or tractors. However, the composite pane according to the invention can also be slightly or strongly curved in one or more spatial directions. Curved panes are common, for example, in glazing in the automotive sector, with typical radii of curvature ranging from approximately 10 cm to approximately 40 m.

[0032] The composite pane can have a functional coating, for example, an IR-reflecting or absorbing coating, a UV-reflecting or absorbing coating, a color-imparting coating, a low-emissivity coating (so-called low-E coating), a heatable coating, a coating with an antenna function, a coating with a splinter-binding effect (splinter-binding coating), or a coating for shielding against electromagnetic radiation, for example, radar radiation. In a preferred embodiment, the coating according to the invention is an electrically conductive coating. This makes it possible, in particular, to realize a low-emissivity coating, an IR-reflecting coating, or a heatable coating.

[0033] The functional coating is preferably applied to a surface of the polymeric disc or to a carrier film within the intermediate layer. The carrier film preferably contains at least polyethylene terephthalate (PET), polyethylene (PE), or mixtures or copolymers or derivatives thereof and preferably has a thickness of 5 µm to 500 µm, particularly preferably 10 µm to 200 µm. This is particularly advantageous for handling, stability, and the optical properties of the carrier film.

[0034] In an advantageous development of the invention, the surface of the polymer pane facing away from the glass pane is provided with a protective coating. This further increases the scratch resistance of the pane. Preferably, thermally curing or UV-curing coating systems based on polysiloxanes, polyacrylates, polymethacrylates, and / or polyurethanes are used. The protective coating preferably has a layer thickness of 1 µm to 50 µm, particularly preferably 2 µm to 25 µm.

[0035] The invention further comprises a method for producing a composite pane according to the invention, wherein a polymeric pane is produced, a glass pane is provided and the polymeric pane is bonded to the glass pane.

[0036] The polymer disc is preferably manufactured by injection molding.

[0037] The glass pane is preferably chemically toughened.

[0038] The glass pane is preferably manufactured as flat glass and cut to the desired size and shape. If the composite pane to be manufactured has a curvature in only one direction, the flat pane can be bent directly when bonding it to the polymer pane due to its small thickness.

[0039] However, especially in the automotive sector, bending in multiple directions typically occurs. In this case, the glass pane preferably receives its final three-dimensional shape before chemical tempering. For this purpose, the glass pane is subjected to a bending process at elevated temperatures, for example, between 500°C and 700°C.

[0040] After bending, the sheet is slowly cooled. Cooling too quickly creates thermal stresses in the sheet, which can lead to deformation during subsequent chemical tempering. The cooling rate is preferably between 0.05 °C / sec and 0.5 °C / sec, particularly preferably between 0.1 and 0.3 °C / sec, until cooling to a temperature of 400 °C. Such slow cooling prevents thermal stresses in the glass, which can lead in particular to optical defects and negatively affect the subsequent chemical tempering. Cooling can then continue, even at higher cooling rates, because the risk of generating thermal stresses is low below 400 °C.

[0041] Chemical tempering preferably takes place at a temperature of 300°C to 600°C, particularly preferably 400°C to 500°C. The glass pane is treated with a molten salt, for example, by immersing it in the molten salt. During the treatment, sodium ions in the glass are exchanged for larger ions, especially larger alkali ions, creating the desired surface compressive stresses. The molten salt is preferably the melt of a potassium salt, particularly preferably potassium nitrate (KNO 3 ) or potassium sulfate (KSO 4 ), most preferably potassium nitrate (KNO 3 ).

[0042] Ion exchange is determined by the diffusion of alkali ions. The desired values ​​for surface compressive stresses and compressive stress depths can therefore be adjusted, particularly by adjusting the temperature and duration of the tempering process. Typical durations range from 2 to 48 hours.

[0043] After treatment with the molten salt, the disc is cooled to room temperature. The disc is then cleaned, preferably with sulfuric acid (H 2 SO 4 ).

[0044] The polymer pane and the glass pane are bonded together by lamination via a thermoplastic interlayer. The production of the laminated glass by lamination is carried out using conventional methods, such as autoclave processes, vacuum bag processes, vacuum ring processes, calender processes, vacuum laminators, or combinations thereof. The bonding of the glass pane and the polymer pane is usually achieved under the influence of heat, vacuum, and / or pressure.

[0045] The composite pane according to the invention is preferably used in means of transport for land, air or water traffic, in particular in trains, ships and motor vehicles, for example as a windshield, roof window, rear window or side window.

[0046] The invention further comprises the use of a chemically toughened glass pane with a thickness of less than or equal to 1 mm in a composite pane to increase the stability and scratch resistance of a polymer pane, preferably a vehicle pane, particularly preferably a windshield, side window, rear window or roof window.

[0047] The invention is explained in more detail below with reference to a drawing and exemplary embodiments. The drawing is a schematic representation and not to scale. The drawing does not limit the invention in any way.

[0048] They show: Fig. 1 shows a cross section through an embodiment of the composite pane according to the invention, Fig. 2 shows a cross section through a further embodiment of the composite pane which is not part of the invention, Fig. 3 shows a schematic diagram of the fracture stability of chemically toughened and non-toughened glass as a function of the scratch depth and Fig. 4 shows a flow diagram of an embodiment of the method according to the invention.

[0049] Fig. 1 shows a composite pane according to the invention, which consists of a polymer pane 1 and a glass pane 2, which are bonded together via an intermediate layer 3. The composite pane is intended, for example, as a side window of a motor vehicle, with the polymer pane 1 being the inner pane in the installed position and the glass pane 2 being the outer pane. Thus, the polymer pane 1 faces the interior of the motor vehicle, and the glass pane 2 faces the exterior.

[0050] The polymer pane 1 is made of polycarbonate (PC) and has a thickness of 3 mm. The polymer pane 1 gives the composite pane an advantageously low weight. The glass pane 2 has a thickness of, for example, 0.5 mm. The thin glass pane 2 only slightly increases the weight of the composite pane but significantly improves its stability and scratch resistance, as well as its acoustic properties.

[0051] The intermediate layer 3 is made of polyurethane (PU) with a thickness of approximately 0.8 mm. When laminating the polyurethane intermediate layer and the polycarbonate pane, surprisingly, diffusion between the intermediate layer 3 and the polymer pane 1 is reduced compared to many other common thermoplastic materials, such as PVB.

[0052] To achieve improved stability, the glass pane 2 is chemically toughened. The compressive stress depth is greater than 50 µm, for example, approximately 100 µm, and the surface compressive stress is, for example, 250 MPa. However, significantly higher values, such as approximately 400 MPa, are also feasible and may be desired in individual cases. Due to the small thickness of the glass pane 2, such a toughening process would not be achievable by thermal methods.

[0053] The chemical composition of glass pane 2 is shown in Table 1, with the missing portion being caused by impurities and contaminants. This composition is particularly suitable for chemical tempering. Table 1 ingredient % by weight SiO2 60,7 Al 2 O 3 7,7 Na2O 13,1 K2O 9,6 MgO 8,4

[0054] Fig. 2shows a further embodiment of the composite pane, which is not part of the invention. The polymer pane 1 is connected to a first glass pane 2 via a first intermediate layer 3 and to a second glass pane 4 via a second intermediate layer 5. The glass panes 2, 4, which have a thickness of 0.2 mm, for example, protect the polymer pane 1 on both sides from scratching and improve the acoustic properties and stability of the pane.

[0055] Fig. 3shows a comparison between the fracture strength of chemically toughened and non-toughened glass in the form of a schematic diagram. The diagram schematically represents the progression of values ​​measured in comparative tests. During the measurements, scratches were created on chemically toughened and non-toughened glass panes using sandpaper of different grits. This results in the abscissa axis of the diagram (scratch depth), with the abscissa axes of both diagrams being to scale. The force required to break the glass pane was then measured.

[0056] It is clear that the fracture stability of non-tempered glass suffers significantly even with shallow scratches. In contrast, shallow and medium-depth scratches have a negligible impact on the fracture stability of chemically toughened glass, whose fracture stability is only slightly reduced with deeper scratches.

[0057] The diagram clearly illustrates an advantage of using chemically toughened glass in the composite pane according to the invention with regard to fracture stability. This result was unexpected and surprising to those skilled in the art.

[0058] Fig. 4shows a flow diagram of an embodiment of the method according to the invention for producing a laminated glass according to the invention. A polymeric pane 1 made of polycarbonate is produced by injection molding. A glass pane 2 is provided as flat float glass with the chemical composition from Table 1. The glass pane 2 is first brought into its final three-dimensional shape by a bending process. After bending, the glass pane 2 is slowly cooled to avoid thermal stresses. A suitable cooling rate is, for example, 0.1 °C / sec. The glass pane 2 is then treated with a melt of potassium nitrate at a temperature of 460 °C for a period of several hours, for example 4 hours, and is chemically toughened in the process. The treatment causes a diffusion-driven exchange of sodium ions for larger potassium ions across the surfaces of the glass. This generates surface compressive stresses.The glass pane 2 is then cooled and then washed with sulfuric acid to remove residues of potassium nitrate.

[0059] The polymer pane 1 and the glass pane 2, along with a thermoplastic PU film positioned between them, are arranged as a stack. The pane composite is then laminated, for example, using a vacuum bag process, with the thermoplastic film forming an intermediate layer 3. List of reference symbols:

[0060] (1)polymer pane (2)glass pane (3)intermediate layer (4)second glass pane (5)second intermediary layer

Claims

1. Composite pane for vehicles, consisting of - a polymeric pane (1) having a thickness of 1.5 mm to 10 mm - a glass pane (2) having a thickness less than or equal to 1 mm bonded in a planar manner to the polymeric pane (1), - a thermoplastic intermediate layer, wherein the polymeric pane (1) and the glass pane (2) are bonded via the thermoplastic intermediate layer (3), wherein the surfaces of the glass pane (2) and of the polymeric pane (1) facing away from each other form the outer surfaces of the composite pane, wherein the components of the composite pane can be provided with coatings, wherein the polymeric pane (1) contains at least polycarbonate (PC) and / or polymethyl methacrylate (PMMA) and wherein the glass pane (2) is a chemically tempered glass pane.

2. Composite pane according to claim 1, wherein the glass pane (2) has a thickness of 0.1 mm to 1 mm, preferably of 0.2 to 0.8 mm, particularly preferably of 0.4 mm to 0.7 mm.

3. Composite pane according to one of claims 1 through 2, wherein the polymeric pane (1) has a thickness of 2 mm to 5 mm, preferably of 2.5 mm to 4 mm, particularly preferably of 3 mm to 4 mm.

4. Composite pane according to one of claims 1 through 3, wherein the thermoplastic intermediate layer (3) has a thickness of 0.2 mm to 1 mm.

5. Composite pane according to claim 4, wherein the thermoplastic intermediate layer (3) contains at least polyurethane or derivatives thereof.

6. Composite pane according to claim 4 or 5, wherein the thermoplastic intermediate layer (3) has a noise reducing effect.

7. Composite pane according to one of claims 1 through 6, wherein the glass pane (2) has a surface compressive stress greater than 100 MPa, preferably greater than 250 MPa, and particularly preferably greater than 350 MPa.

8. Composite pane according to one of claims 1 through 7, wherein the compressive stress depth of the glass pane (2) is at least one tenth, preferably at least one sixth, of the thickness of the glass pane (2).

9. Composite pane according to one of claims 1 through 8, wherein the glass pane (2) contains from 55 wt.-% to 72 wt.-% silicon oxide (SiO2), from 5 wt.-% to 10 wt.-% aluminum oxide (Al2O3), from 10 wt.-% to 15 wt.-% sodium oxide (Na2O), from 7 wt.-% to 12 wt.-% potassium oxide (K2O), and from 6 wt.-% to 11 wt.-% magnesium oxide (MgO).

10. Method for producing a composite pane according to one of claims 1 through 9, wherein - a polymeric pane (1) is produced, - a glass pane (2) is chemically tempered, and - the polymeric pane (1) is bonded to the glass pane (2) in a planar manner.

11. Method according to claim 10, wherein the glass pane (2) a) is bent at a temperature of 500°C to 700°C and the subsequent cooling rate to a temperature of 400 °C is from 0.05 °C / sec to 0.5 °C / sec and b) is chemically tempered.

12. Method according to claim 10 or 11, wherein the glass pane (2) is chemically tempered in a salt melt, preferably a potassium nitrate (KNO3) melt, at a temperature of 300°C to 600°C for a period of 2 hours to 48 hours.

13. Use of a chemically tempered glass pane (2) in a composite pane according to one of claims 1 through 9 to increase the stability and scratch resistance of a polymeric pane, preferably a vehicle pane, particularly preferably a windshield, side window, rear window, or roof panel.