COMPOSITE PANE WITH IMPROVED COLOR EFFECT

Abstract

A composite pane includes an outer pane and an inner pane that are joined to one another via a thermoplastic intermediate layer, wherein the composite pane has at least one functional film that contains at least one metal layer, and the thermoplastic intermediate layer is formed with at least one thermoplastic film that contains refractive-index-reducing agents and these refractive-index-reducing agents reduce the refractive index of the thermoplastic film by at least 0.05 in the optically visible range between 380 nm and 780 nm.

Claims

1. A composite pane comprising an outer pane and an inner pane that are joined to one another via a thermoplastic intermediate layer, and at least one functional film that contains at least one metal layer, and the thermoplastic intermediate layer is formed with at least one thermoplastic film that contains refractive-index-reducing agents and said refractive-index-reducing agents reduce the refractive index of the thermoplastic film by at least 0.05 in the optically visible range between 380 nm and 780 nm.

2. The composite pane according to claim 1, wherein the functional film includes at least one silver layer, aluminum layer, copper layer, palladium layer, platinum layer, or gold layer as the metal layer.

3. The composite pane according to claim 1, wherein the functional film has two to four metal layers.

4. The composite pane according to claim 1, wherein the functional film includes at least two dielectric layers sandwiching the metal layer.

5. The composite pane according to claim 1, wherein the refractive index of the thermoplastic film is reduced between 0.05 and 0.15 in the optically visible range by the refractive-index-reducing agents contained therein.

6. The composite pane according to claim 1, wherein the refractive-index-reducing agents are nanoparticles having a refractive index n<1.4 in the optically visible range.

7. The composite pane according to claim 1, wherein the refractive-index-reducing agents are, contain, or comprise metal fluoride nanoparticles, or hollow SiO.sub.2 nanoparticles.

8. The composite pane according to claim 1, wherein the thermoplastic film contains at least 1 wt.-% refractive-index-reducing agents based on the a total weight in a volume of the thermoplastic film.

9. The composite pane according to claim 1, wherein the refractive-index-reducing agents are nanoparticles with an average diameter of 5 nm to 200 nm.

10. The composite pane according to claim 1, wherein the thermoplastic film is a polyvinyl butyral (PVB) film, an ethylene vinyl acetate (EVA) film, or a polyurethane (PU) film.

11. The composite pane according to claim 1, wherein the thermoplastic film has a thickness of at least 0.1 mm to a maximum of 2 mm.

12. The composite pane according to claim 1, wherein the thermoplastic intermediate layer is formed from two or more thermoplastic films having a refractive index different from one another.

13. A method for producing a composite pane according to claim 1 comprising the outer pane and the inner pane that are joined to one another via the thermoplastic intermediate layer, and the at least one functional film that contains the at least one metal layer, and the thermoplastic intermediate layer is formed with the at least one thermoplastic film that contains refractive-index-reducing agents, and the refractive-index-reducing agents reduce the refractive index of the thermoplastic film by at least 0.05 in the visible range, comprising the steps: S1: providing the at least one thermoplastic film containing refractive-index-reducing agents; S2: providing the functional film on the outer pane, the inner pane, the thermoplastic film, and/or a carrier film; S3: forming a stack sequence from the outer pane, the inner pane and the thermoplastic film, optionally the carrier film with a functional film, and S4: bonding the stack sequence under the action of pressure, heat, and/or vacuum.

14. The method according to claim 13, wherein in step S1, the thermoplastic film contains metal fluoride nanoparticles, or hollow SiO.sub.2 nanoparticles as refractive-index-reducing agents.

15. The method according to claim 13, wherein in step S1, two or more thermoplastic films having a different refractive index are used.

16. The composite pane according to claim 3, wherein the functional film has 2, 3, or 4 silver layers.

17. The composite pane according to claim 6, wherein the refractive-index-reducing agents are nanoparticles having a refractive index n<1.3 in the optically visible range.

18. The composite pane according to claim 7, wherein the metal fluoride nanoparticles are MgF.sub.2 or CaF.sub.2 nanoparticles.

19. The composite pane according to claim 8, wherein the refractive-index-reducing agents are nanoparticles.

20. The composite pane according to claim 10, wherein the thermoplastic film is a polyvinyl butyral (PVB) film.

Description

[0083] The figures depict:

[0084] FIG. 1 a schematic cross-section through a layer structure for a composite pane according to the invention using the example of an HUD-compatible composite pane laminate (HUD composite pane/HUD laminate);

[0085] FIG. 2 a diagram of the refractive index n and wavelength for PVB films having a differently reduced refractive index

[0086] FIG. 3 the color values a*b* of the composite panes of Table 1 with the thermoplastic films PVB1, PVB 2, and PVB 3 in a color diagram.

[0087] FIG. 1 depicts a schematic cross-section through a layer structure 10 for a composite pane 100 according to the invention using the example of an HUD laminate, as examined with the optical simulation program. The values for the comparative optically simulated measurements, once for a composite pane 100 with a clear standard PVB film 4A (prior art) and once with a clear PVB film 4B with a refractive index n reduced according to the invention are shown in Table 3. The layer structure 10 for the composite pane 100 comprises an outer pane 1, an inner pane 2, and an intermediate layer 3. The inner pane 2 and the outer pane 1 are, in the example used as the basis of the optical simulation (Table 3), 2.1-mm-thick clear glass panes, available, for example, under the tradename Planiclear. The intermediate layer 3 comprises a thermoplastic film 4 (4A prior art/4B with refractive index n reduced according to the invention) in the comparative examples of Table 3 in each case a PVB film 4A (PVB1 standard/prior art) and PVB film 4B (PVB2/with reduced refractive index) with a thickness of 0.76 mm. On the outer side III of the inner pane 2 facing the thermoplastic film 4 (4A/4B), a multilayer functional film 5 with a transparent silver layer 6 is arranged in the intermediate layer 3. The functional film 5 of the example composite panes 100 comprises a silver layer 6 with a thickness of 12.5 nm and further dielectric layers (5a, 5b, 5c, 5d, 5e, 5f). The layer structure for the optical simulations of Table 3 is shown in detail in Table 4. The functional film 5 can be applied to the inner pane, for example, by conventional methods, such as sputtering. It has been shown that the composite panes 100 according to the invention present, with virtually identical transmittance values TL(A), a significant, positive effect in the color effect in reflection. The reflection color of the composite pane 100 is shifted into the green range by the PVB film 4B according to the invention (Table 3, PVB2) with the reduced refractive index n. Also, the HUD p-pol reflection color becomes more color-neutral with the PVB film 4B (PVB2) with a reduced refractive index n. This means that with the composite pane 100 manufactured according to the invention with the PVB film 4B with the reduced refractive index n, a disruptive color shift in an HUD projection can be reduced or avoided in comparison with the prior art (use of the standard PVB film 4A). The closer the color values a* and b* come to zero, the more color-neutral the color effect in reflection. In addition, surprisingly, in the comparison of the two HUD composite pane laminates 100 using the PVB2 4B with the reduced refractive index, a polarization ratio (p-polarization) increased by 0.007 was found.

TABLE-US-00006 TABLE 4 Structure of a composite pane 100 using the example of an HUD composite pane with a silver layer compared to a PVB1 (4A) and a PVB2 (4B) as a thermoplastic film 4 (4A/4B) HUD Composite pane Layer thickness Outer pane 1 Clear glass pane 2.1 mm Planiclear PLC Thermoplastic film 4 Standard PVB1 4A 0.76 mm (prior art) or PVB2 with reduced refractive index 4B (according to the invention) Si.sub.3N.sub.4 50 nm Functional film 5 SiZrNx 10 nm ZnO 10 nm NiCr 0.3 nm Ag [metal layer 6] 12.5 nm ZnO 10.0 nm SiZrNx 10.0 nm Si.sub.3N.sub.4 10.0 nm Inner pane 2 Clear glass pane 2.1 mm Planiclear PLC

[0088] FIG. 2 depicts a diagram of the refractive index n and wavelength for four PVB films with a differently reduced refractive index. The simulations that yielded the values shown in Table 1 to 3 were performed with PVB1 (standard/reference/refractive index at 500 nm approx. 1.48), PVB 2 (refractive index at 500 nm approx. 1.43; 0.05), and PVB 3 (refractive index at 500 nm approx. 1.35; 0.13). With PVB 4, an additional PVB film with a refractive index at 500 nm, of approx. 1.39 is graphically depicted.

[0089] FIG. 3 depicts the color values a* and b* determined with the optical simulation program for the composite panes 100 of Table 1 with the different thermoplastic films PVB1 (standard/reference), PVB 2 (refractive index 0.05), and PVB 3 (refractive index at 500 nm n 0.13) in a color coordinate diagram.

[0090] It can be seen that with the increasing reduction of the refractive index, the external reflection is less blue at 8 and less red at 60. The tendencies toward color neutrality with the reduction of the refractive index of the PVB film 4 represented by the arrows X (value of reflection at 8) and Y (value of reflection at 60) make possible the assumption that a further drop in the refractive index n of the PVB film used could further strengthen this effect of the improved color effect in reflection of the composite pane 100.

[0091] The composite pane according to the invention surprisingly exhibits good optical and aesthetic properties, whereby, in particular, undesirable color tones in reflection of the composite pane can be minimized or even avoided.

[0092] This is possible according to the invention without the other properties of the composite pane being negatively affected.

[0093] According to the invention, composite panes with an improved color impression in reflection are thus provided. Advantageously, the improved color effect and the aesthetic visual effect improved thereby can be achieved without other properties of the composite pane being negatively affected.

LIST OF REFERENCE CHARACTERS

[0094] 100 composite pane [0095] 10 layer structure [0096] 1 outer pane [0097] 2 inner pane [0098] 3 intermediate layer [0099] 4 thermoplastic film [0100] 4A standard PVB film (prior art) [0101] 4B PVB film 4B (PVB2/with refractive index reduced according to the invention). [0102] 5 functional film [0103] 5a, 5b, 5c, 5d, 5e, 5f dielectric layers [0104] 6 metal layer [0105] I outer surface of the outer pane 1 [0106] II inner surface of the outer pane 1 [0107] III outer surface of the inner pane 2 [0108] IV inner surface of the inner pane 2 [0109] X tendency values of reflection at 8 with decreasing refractive index of the PVB [0110] Y tendency values of reflection at 60 with decreasing refractive index of the PVB