LAMINATED GLAZING AND THE PRODUCTION PROCESS FOR LAMINATED GLAZING

Description

[0001] The invention relates to a composite disc and a method for manufacturing the composite disc.

[0002] Laminated glass, especially that used as a motor vehicle windshield, consists of two panes and at least one thermoplastic film sandwiched between them. Typically, at least one pane is made of flat glass, which in industrial mass production is often manufactured using the float glass process.

[0003] In the float glass process, molten glass is poured from one side onto a bath of liquid tin (float bath). For example, the temperature at the inlet of the tin bath is approximately 1000 °C. The lighter molten glass floats on the tin and spreads evenly across its surface. Due to the surface tension of the tin, the glass forms a very smooth surface. At a cooler end of the tin bath, the solidified glass is continuously drawn out in ribbon form and then cooled. After sufficient cooling, glass sheets of the desired size are cut from the ribbon.

[0004] The distribution of the molten glass on the tin bath determines an equilibrium thickness of the glass, which, however, is too great for many applications. To reduce the sheet thickness, the already solidified glass is pulled from the tin bath by actively driven (top) rollers, thus stretching the glass ribbon. The thickness of the glass can be adjusted by changing the speed of the rollers; a higher speed is used to produce thinner glass, and a lower speed for thicker glass.

[0005] As is known to those skilled in the art, glass produced using the float glass process exhibits a certain unevenness or waviness on its surfaces due to being drawn out of the tin bath. Accordingly, both glass surfaces have elongated protrusions and depressions arranged in parallel, each extending in the direction of the glass ribbon's pull from the tin bath. These elongated protrusions and depressions correspond to wave crests and troughs, arranged alternately perpendicular to the direction of pull. These elongated structures of the glass are also known to those skilled in the art as "float lines." The thinner the glass, the greater the tensile force must be on the glass ribbon, which in turn results in more pronounced float lines.In the industrial mass production of flat glass, rectangular glass sheets are typically cut to length with their longer dimension in the direction of the strip, so that the float lines extend parallel to the longer dimension of the glass sheets.

[0006] The industrial production of thin glass using the fusion-draw process is also well-known. In this process, the molten glass is typically drawn downwards from the melting furnace through a nozzle by means of rollers. Similar to the float glass process, the fusion-draw process creates elongated ridges and depressions on the glass surface, corresponding to wave crests and troughs, which are arranged alternately perpendicular to the drawing direction, resulting in a slight waviness on the glass surface. Those skilled in the art know these elongated structures of thin glass produced using the fusion-draw process as "draw lines."

[0007] Thermoplastic films produced by extrusion processes are also typically characterized by undesirable waviness resulting from the manufacturing process. This manifests as variations in thickness (elongated ridges and depressions) perpendicular to the extrusion direction. This undesirable waviness must be distinguished from intentionally created roughness, which is typically embossed into the thermoplastic films to facilitate venting of the layer stack during the production of the laminated sheet. The undesirable waviness and the intentionally created roughness differ significantly in the spacing of adjacent elongated ridges or depressions. The deliberately created roughness is described, for example, in EP 3 029 000 A1, EP 3 029 001 A1, EP 3 029 002 A1, EP 3 029 003 A1, EP 2 881 376 A1, EP 2 674 295 A1, WO 2016 / 030284 A1, WO 95 / 19885 A1 and WO 2008 / 003789 A1.

[0008] In practical applications, float or drawing lines can adversely affect the optical properties of the flat glass, as the waviness of the glass creates a lens effect with locally varying refractive power. This effect is particularly pronounced when the float or drawing lines overlap unfavorably with the manufacturing-related waviness of the thermoplastic film. For example, when tilting one's head from side to side or from top to bottom through a windshield in a vehicle, the locally varying refractive power can cause objects to appear distorted when viewed through it.

[0009] The invention is based on the objective of providing a composite disc with improved optical properties and a method for manufacturing such a composite disc.

[0010] These and other problems are solved according to the invention by a laminated glass pane with the features of claim 1. Advantageous embodiments of the invention are described in the dependent claims. The present invention relates to a laminated glass pane, in particular a laminated glass pane, comprising a first pane, a second pane, and at least one thermoplastic film arranged between the two panes. At least one of the two panes is in the form of flat glass and, due to its manufacturing process, has on at least one pane surface, in particular on both pane surfaces, a plurality of elongated protrusions (wave crests) and elongated depressions (wave troughs) extending along a first (pane) direction and arranged alternately in a second (pane) direction perpendicular to the first (pane) direction.The first direction generally corresponds to a drawing direction during the production of a glass ribbon from which the pane is formed, for example, the drawing direction from the float bath (tin bath) of a pane produced using the float process (the raised areas and depressions correspond to the float lines) or the drawing direction from the melting strip of thin glass produced using the fusion-draw process (the raised areas and depressions correspond to the draw lines). The elongated raised areas and elongated indentations of the pane are typically parallel to each other and arranged in an alternating sequence.

[0011] The thermoplastic film of the composite disc according to the invention is produced by an extrusion process in which plasticized material in the form of a film is conveyed from an extruder. Due to the manufacturing process, the thermoplastic film also exhibits a certain degree of waviness or unevenness on its surface. At least one film surface, and in particular both film surfaces, of the thermoplastic film has a plurality of elongated ridges (crests) and elongated depressions (troughs) that extend along a first (film) direction and are arranged alternately in a second (film) direction perpendicular to the first (film) direction. The first direction corresponds to the extrusion direction of the thermoplastic film. The elongated ridges and depressions of the thermoplastic film are typically arranged parallel to each other and in an alternating sequence.

[0012] The elongated ridges (wave crests) and depressions (wave troughs) of the thermoplastic film, as described in the invention, represent and are caused by the manufacturing-related, and actually undesirable, surface waviness. According to the invention, the distance between adjacent ridges or depressions is greater than or equal to 50 mm. This is to be distinguished from a desired surface roughness, which is often deliberately embossed into the film surface in the form of elongated ridges and depressions to facilitate venting during the lamination of the composite panel, where the distance between adjacent ridges or depressions is typically less than 1 mm.

[0013] Essential to the present invention is that the elongated protrusions (and elongated depressions) of at least one sheet of flat glass are arranged at an angle other than 90° to the extrusion direction of the thermoplastic film, i.e., at an angle other than 90° to the elongated protrusions (and elongated depressions) of the thermoplastic film. Advantageously, the elongated protrusions are arranged at an angle of 0° to 45°, particularly preferably 0°, to the extrusion direction of the thermoplastic film.

[0014] As the inventors first recognized, flat glass panes conform to the shape of the thermoplastic film during lamination and thus acquire a certain waviness due to the waviness of the thermoplastic film. This effect is particularly pronounced in very thin flat glass panes with thicknesses of less than 2.1 mm. The inventors discovered that the claimed relative arrangement of at least one pane with manufacturing-related waviness and the thermoplastic film can achieve an advantageous effect on the local lens effect of the pane. Without being bound to any specific theory, it is stated that the waviness imposed on the pane by the thermoplastic film can compensate for or homogenize the manufacturing-related waviness of the pane, thereby reducing relatively large differences in local optical refractive power.The optical properties of the disc are thereby significantly improved, in particular, distortions of objects seen through it are reduced. For this purpose, the elongated protrusions of at least one disc are advantageously arranged at an angle of 0° to 45° to the extrusion direction of the thermoplastic film. It is currently assumed that the best effect in terms of reducing large differences in local optical refractive power can be achieved when the elongated protrusions of a disc are arranged at an angle of 0° to the extrusion direction of the thermoplastic film.

[0015] The intended effect occurs particularly well with very thin discs, and according to the invention, it is preferred that at least one disc with manufacturing-related elongated protrusions and depressions has a disc thickness of less than 2.1 mm. The inventors were able to demonstrate that with such thin discs, a particularly strong effect can be achieved with regard to reducing large differences in local optical refractive power, since, on the one hand, the float or draw lines are more pronounced in thinner discs, and on the other hand, thin discs undergo greater changes during lamination due to the corrugation of the thermoplastic film. It is particularly advantageous for at least one disc with manufacturing-related corrugation to have a disc thickness in the range of 0.5 mm to 1.1 mm. Such thin discs are advantageously produced using the fusion-draw process.The inventors were able to show that the inventive effect (improvement of optical properties) occurs particularly strongly for this disk thickness.

[0016] In an advantageous embodiment of the invention, one disc with manufacturing-related waviness has a thickness of less than 2.1 mm, and the other disc (which may also exhibit manufacturing-related waviness) has a thickness in the range of 1.4 mm to 2.6 mm. If both discs are relatively thin, it is advantageous to achieve the intended effect according to the invention to a significant degree for both discs. Alternatively, if one disc is thicker, it is advantageous to achieve the intended effect according to the invention to a significant degree only for the thinner disc, with the thicker disc contributing to an improvement in the stability of the composite disc.

[0017] In a further advantageous embodiment of the invention, one disc with manufacturing-related waviness has a thickness of less than 2.1 mm, and the other disc (which may also exhibit manufacturing-related waviness) has a thickness of at least 2.1 mm, particularly in the range of 2.1 mm to 2.6 mm. In this configuration, the advantageous effect of the invention occurs to a significant degree in the thinner disc, while the thicker disc results in a considerable improvement in the stability of the composite disc.

[0018] According to the present invention, the first and / or the second pane can be provided with elongated protrusions and depressions (wave structure) due to the manufacturing process, with the above embodiments regarding the relative arrangement of the elongated protrusions or depressions of the pane and the thermoplastic film applying separately to each pane. In particular, with two relatively thin panes (pane thickness less than 2.1 mm), a particularly good improvement in the optical properties of the laminated pane can be achieved according to the invention.

[0019] The thermoplastic film contains at least one thermoplastic polymer, preferably ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), or polyurethane (PU), or mixtures, copolymers, or derivatives thereof, particularly preferably PVB. The thickness of the thermoplastic film is, for example, 0.2 mm to 2 mm, and particularly in the range of 0.3 mm to 1 mm.

[0020] The first and / or second pane exhibiting manufacturing-related waviness is a flat glass, in particular float glass produced using the float glass process or thin glass produced using the fusion-draw process. It could be, for example, quartz glass, borosilicate glass, aluminosilicate glass, or soda-lime glass. Very thin glasses with thicknesses in the range of, for example, 0.5 mm to 1.1 mm are produced particularly using the fusion-draw process.

[0021] When installed, laminated windshields typically have two vertically extending edges, which abut, for example, the nearest body pillars (such as the A-pillars), and two horizontally extending edges, which are located, for example, on the roof and engine compartment sides. The elongated ridges and indentations resulting from the manufacturing process on at least one individual pane, and especially on both individual panes, typically run vertically. In the industrial mass production of laminated windshields, the thermoplastic film required for lamination is typically rolled up along the extrusion direction and unwound accordingly.According to one embodiment of the invention, the thermoplastic film is cut to length and laminated with the two individual panes such that the elongated protrusions of the thermoplastic film are arranged parallel to the manufacturing-related elongated protrusions of the composite pane and therefore extend in the vertical direction of the windshield.

[0022] The invention further relates to a method for manufacturing a composite disk designed as described above, according to the invention. It comprises the following steps: Providing the first pane, providing the second pane, wherein at least one pane is in the form of a flat glass and has elongated protrusions and elongated depressions on at least one surface, laminating the two panes with a thermoplastic film arranged between the two panes, wherein the thermoplastic film has elongated protrusions and elongated depressions on at least one surface, wherein the two panes and the thermoplastic film are arranged such that the elongated protrusions of the at least one pane and the elongated protrusions of the thermoplastic film are aligned at an angle other than 90°.

[0023] Furthermore, the invention extends to the use of the composite disc according to the invention in means of transport for traffic on land, in the air or on water, in particular in motor vehicles and in particular as a windshield in a motor vehicle.

[0024] The above-mentioned embodiments and features of the invention can be provided individually or in any combination.

[0025] The invention will now be explained in more detail using exemplary embodiments, with reference to the accompanying figures. These show: Fig. 1 a schematic representation of a thermoplastic film partially unwound from a roll; Fig. 2 a cross-sectional view of the thermoplastic film according to the diagram in Fig. 1 section line AA shown; Fig. 3 a schematic representation of the arrangement of individual discs for cutting the thermoplastic film to length Fig. 1Fig. 4 is an exploded view of the composite pane according to a preferred embodiment of the invention; Fig. 5 is a composite pane, in particular a windshield of a motor vehicle, according to a preferred embodiment of the invention; Fig. 6 is a diagram illustrating the local optical refractive power of a conventional composite pane (left) and a composite pane according to the invention (right); Fig. 7 is a flowchart of a method for manufacturing the composite pane according to the invention in a preferred embodiment of the invention.

[0026] First, be Figure 1Figure 5 shows a schematic representation of a thermoplastic film 4 partially unwound from a roll 5. The thermoplastic film 4 preferably consists of PVB. Alternatively, the thermoplastic film can consist of another suitable material such as polyamide or polyethylene. The thermoplastic film 4 is produced by extrusion, the extrusion direction of the thermoplastic film 4 corresponding to the winding or unwinding direction of the roll 5. Fig. 1 The extrusion or unwinding direction is marked with the arrow R1.

[0027] Figure 2 shows a cross-sectional view of the thermoplastic film 4 according to the in Fig. 1The section line AA is shown. At least one surface 6 of the thermoplastic film 4 is recognizably wavy and exhibits a plurality of elongated projections 7 (hereinafter referred to as film projections 7) and elongated depressions 8 (hereinafter referred to as film depressions 8) in a parallel arrangement. The film projections 7 and film depressions 8 each extend in the extrusion direction R1. Transverse to the extrusion direction, the film projections 7 and film depressions 8 are arranged alternately. The film projections 7 and film depressions 8 are wavy, so that the surface 6 of the thermoplastic film exhibits a waviness. It should be noted that Figure 2The schematic representation shows that typically the opposite surface 6' is also similarly wavy and provided with foil elevations 7 and foil depressions 8.

[0028] Figure 3 Figure 1 shows a schematic representation illustrating a preferred arrangement of (individual) discs 2, 3 relative to the thermoplastic film 4 for the production of a composite disc 1 according to the invention. Accordingly, the thermoplastic film 4 is cut to length such that the disc edges, which extend in the transverse direction of the vehicle in the installed state, are arranged transversely to the extrusion direction R1.

[0029] Fig. 4Figure 1 shows an exploded view of the composite disk 1 according to a preferred embodiment of the invention. The composite disk 1 comprises a first disk 2 and a second disk 3, as well as a thermoplastic film 4 between the two disks 2, 3, which is cut from a roll 5. Due to the manufacturing process, each disk 2, 3 has a plurality of elongated projections 11 (hereinafter referred to as disk projections 11) and elongated depressions 12 (hereinafter referred to as disk depressions 12) in a parallel arrangement, projecting from a surface 13. The disk projections 11 and disk depressions 12 each extend along a direction that is Fig. 4The disk projections 11 and disk depressions 12 are designated by the arrow R2. Perpendicular to the direction R2, the disk projections 11 and disk depressions 12 are arranged alternately. The disk projections 11 and disk depressions 12 are corrugated, so that the surface 13 of each of the two disks 2, 3 exhibits corrugation. Typically, both opposing surfaces 13, 13' of each disk 2, 3 are corrugated and exhibit disk projections 11 and disk depressions 12.

[0030] As in Figure 4 As illustrated, in the laminated state, the disc protrusions 11 and disc depressions 12 of the first disc 2 are arranged parallel to the disc protrusions 11 and disc depressions 12 of the second disc 3. Furthermore, the disc protrusions 11 and disc depressions 12 of both discs 2 and 3 are arranged parallel to the extrusion direction R1 and parallel to the film protrusions 7 and film depressions 8, respectively.

[0031] Furthermore, the first pane 2 is thinner than 2.1 mm. The thickness of the second pane 3 is in the range of 0.5 mm or 1.1 mm. Alternatively, the thickness of the second pane 3 can be greater than 2.1 mm, and in particular in the range of 2.1 mm to 2.6 mm. The first pane 2 and the second pane 3 are made of glass and are manufactured, for example, using the float glass process or the fusion-draw process. It is also conceivable that only the first pane 2 consists of glass and has pane projections 11 and pane depressions 12, and that the second pane 3 is made of a polymer.

[0032] Fig. 5 Figure 1 shows a further embodiment of the composite disc 1 according to the invention, in particular for use as a windshield of a motor vehicle. As shown in Figure 1, the composite disc 1 is further developed in this context, particularly for use as a windshield of a motor vehicle. Fig. 5As illustrated, the laminated glass unit 1 comprises a first glass unit 2, a second glass unit 3, and a thermoplastic film 4. The laminated glass unit 1 has four edges: an upper edge 9 and a lower edge 10, which extend in the transverse direction (of the vehicle) when installed, and two lateral edges 14, which extend in the vertical direction (of the vehicle) when installed. The film protrusions 7 and film indentations 8 each extend along a shortest connecting line between the upper edge 9 and the lower edge 10 (i.e., extrusion direction R1). The first and / or second glass unit 2, 3 is designed as flat glass and has protrusions 11 and indentations 12, which also extend along a shortest connecting line between the upper edge 9 and the lower edge 10 (i.e., tensile direction R2).

[0033] Fig. 6Figure 1 shows a diagram indicating the local optical refractive power D of a conventional laminated glass pane (left) and a laminated glass pane 1 according to the invention (right). The first pane 2 is a 0.5 mm thick aluminosilicate glass produced using the fusion-draw process, and the second pane 3 is a 2.1 mm thick soda-lime glass produced using the float glass process.

[0034] In the two left-hand illustrations, which correspond to the conventional case, the extrusion direction R1 of the thermoplastic film 4 is at an angle of 90° to the direction R2 of the disc protrusions 11 and disc recesses 12 of the two discs 2, 3. In the two right-hand illustrations, which correspond to the invention, the extrusion direction R1 of the thermoplastic film 4 is at an angle of 0° to the direction R2 of the disc protrusions 11 and disc recesses 12 of the two discs 2, 3, i.e., the extrusion direction R1 and the direction R2 are parallel to each other.

[0035] The diagram illustrates the optical refractive power D [mdpt] in the transmission through the composite lenses using different shades of gray. The two upper images represent the horizontal optics (i.e., change in optical refractive power in the horizontal direction) (Case A). The two lower images represent the vertical optics (i.e., change in optical refractive power in the vertical direction) (Case B).

[0036] As can be clearly seen in the two upper illustrations (Case A), the composite pane according to the invention (right illustration) achieves a significant reduction in the changes in optical refractive power D, especially in the interior. Compared to the conventional case, the optical refractive power D of the composite pane is considerably more homogeneous, thus improving transparency. Regarding vertical optics (Case B, lower illustrations), a slight deterioration appears to occur with the invention (increase in the changes in optical refractive power D); however, this is hardly noticeable in practice, since changes in optical refractive power D in the vertical direction are typically far less disruptive than changes in optical refractive power in the horizontal direction. Therefore, the composite pane according to the invention achieves a significant improvement in optical properties for transparency.

[0037] Fig. 7shows a flowchart of a method for manufacturing the composite disc according to a preferred embodiment of the invention.

[0038] The method comprises providing (S1) the first disc 2, providing (S2) the second disc 3, and laminating (S3) the two discs 2, 3 with a thermoplastic film 4 arranged between the two discs, wherein the two discs 2, 3 and the thermoplastic film 4 are arranged such that the manufacturing-related disc protrusions 11 and disc depressions 12 of the first disc 2 and / or second disc 3 are aligned at an angle other than 90°, in particular at an angle of 0° to 45°, preferably 0°, to the extrusion direction of the thermoplastic film 4.

[0039] From the foregoing, it follows that the invention provides a composite lens with significantly reduced local variations in optical refractive power and thus improved transparency. Conventional methods for manufacturing composite lenses can be easily modified to achieve cost-effective production of the composite lens. Reference symbol list

[0040] 1 Laminated glass pane 2 First pane 3 Second pane 4 Thermoplastic film 5 Roll 6.6' Film surface 7 Film elevation 8 Film depression 9 Upper pane edge 10 Lower pane edge 11 Pane elevation 12 Pane depression 13.13' Pane surface 14 Side pane edge

Claims

1. Composite pane (1) that comprises a first pane (2), a second pane (3), and at least one thermoplastic film (4) arranged between the two panes (2, 3), wherein - at least one pane (2, 3) is in the form of a flat glass and at least one pane surface (13, 13') has a plurality of elongated elevations (11) and elongated depressions (12) that extend along a first pane direction and are alternatingly arranged in a second pane direction perpendicular to the first pane direction, - the thermoplastic film (4) is produced by extrusion and at least one film surface (6, 6') has a plurality of elongated elevations (7) and elongated depressions (8) that extend along a first film direction and are alternatingly arranged in a second film direction perpendicular to the first film direction, wherein the distance between adjacent elevations (7) and the distance between adjacent depressions (8) of the thermoplastic film (4) are greater than or equal to 50 mm, and wherein the elongated elevations (11) of the at least one pane (2, 3) are arranged at an angle different from 90° relative to the elongated elevations (7) of the thermoplastic film (4).

2. Composite pane (1) according to claim 1, wherein the elongated elevations (11) of the at least one pane (2, 3) are arranged at an angle from 0° to 45°, preferably 0°, relative to the elongated elevations (7) of the thermoplastic film (4).

3. Composite pane (1) according to one of claims 1 through 2, wherein at least one pane (2, 3) with elongated elevations (11) and elongated depressions (12) has a pane thickness of less than 2.1 mm hat.

4. Composite pane according to claim 3, wherein at least one pane (2, 3) with elongated elevations (11) and elongated depressions (12) has a pane thickness in the range from 0.5 mm to 1.1 mm.

5. Composite pane according to claim 3, wherein one pane (2) has elongated elevations (11) and elongated depressions (12) and has a pane thickness of less than 2.1 mm, and the other pane (3) has a pane thickness in the range from 1.4 mm to 2.6 mm.

6. Composite pane according to claim 3, wherein one pane (2) has elongated elevations (11) and elongated depressions (12) and has a pane thickness of less than 2.1 mm, and the other pane (3) has a pane thickness of at least 2.1 mm, in particular in the range from 2.1 mm to 2.6 mm.

7. Composite pane according to one of claims 1 through 6, wherein the first pane (2) and second pane (3) have in each case elongated elevations (11) and elongated depressions (12).

8. Composite pane according to claim 7, wherein the elongated elevations (11) and elongated depressions (12) of the first pane (2) are arranged parallel relative to the elongated elevations (11) and elongated depressions (12) of the second pane (3).

9. Composite pane according to one of claims 1 through 8, wherein at least one pane (2, 3) with elongated elevations (11) and elongated depressions (12) is produced in the float glass method or the fusion draw method.

10. Composite pane according to one of claims 1 through 9, wherein the thermoplastic film (4) is made of polyvinyl butyral (PVB).

11. Composite pane according to one of claims 1 through 10, which has two pane edges (9, 10) extending in the transverse direction in the installed state and two pane edges (14) extending in the vertical direction in the installed state, wherein the elongated elevations (11) and elongated depressions (12) of the first pane (2) and / or the second pane (3) extend along a line, preferably the shortest line that connects the two pane edges (9, 10) extending in the transverse direction to one another.

12. Method for producing a composite pane (10) according to one of claims 1 through 11, which comprises the following steps: - Providing the first pane (2), - Providing the second pane (3), - Laminating the two panes (2, 3) with at least one thermoplastic film (4) arranged between the two panes (2, 3), characterized in that the two panes (2, 3) and the thermoplastic film (4) are arranged such that the elongated elevations (11) at least of one pane (2, 3) are arranged at an angle different from 90° relative to the elongated elevations (7) of the thermoplastic film (4).

13. Use of the composite pane (1) according to one of claims 1 through 11 in means of transportation for travel on land, in the air, or on water, in particular in motor vehicles and in particular as a windshield in a motor vehicle.