VEHICLE PANE WITH REDUCED EMISSIVITY AND LIGHT REFLECTION

Abstract

A vehicle pane with reduced emissivity and light reflection, includes a substrate having an exposed interior-side surface, an emissivity-reducing coating containing at least one layer based on a transparent conductive oxide (TCO) on the interior-side surface, and an anti-reflection coating based on nanoporous silicon oxide on the emissivity-reducing coating.

Claims

1. A vehicle pane with reduced emissivity and light reflection, comprising: a substrate having an exposed interior-side surface, an emissivity-reducing coating containing at least one layer based on a transparent conductive oxide on the interior-side surface, and an anti-reflection coating based on nanoporous silicon oxide on the emissivity-reducing coating.

2. The vehicle pane according to claim 1, wherein the anti-reflection coating is a sol-gel coating, in which closed and/or open nanopores are formed.

3. The vehicle pane according to claim 1, wherein the anti-reflection coating has pores with a size from 1 nm to 500 nm.

4. The vehicle pane according to claim 1, wherein the anti-reflection coating has a refractive index from 1.2 to 1.4 and a thickness from 50 nm to 150 nm.

5. The vehicle pane according to claim 1, wherein the layer based on a transparent conductive oxide (TCO) is based on fluorine-doped tin oxide (FTO) or antimony-doped tin oxide (ATO) and has a thickness from 100 nm to 600 nm.

6. The vehicle pane according to claim 1, wherein the emissivity-reducing coating comprises the following layers, starting from the substrate: a blocking layer against alkali diffusion with a refractive index of at least 1.9, a lower anti-reflection layer with a refractive index of at most 1.8, the layer on a transparent conductive oxide, which is indium tin oxide (ITO), and a barrier layer to regulate oxygen diffusion with a refractive index of at least 1.9.

7. The vehicle pane according to claim 1, wherein the emissivity-reducing coating comprises the following layers, starting from the substrate: a blocking layer against alkali diffusion with a refractive index of at least 1.9, a lower anti-reflection layer with a refractive index of at most 1.8, the layer based on a transparent conductive oxide, which is indium tin oxide, a barrier layer to regulate oxygen diffusion with a refractive index of at least 1.9, and an upper anti-reflection layer with a refractive index of at most 1.8.

8. The vehicle pane according to claim 6, wherein the blocking layer contains a metal, a nitride, or a carbide, the lower anti-reflection layer contains an oxide, the barrier layer contains a metal, a nitride, or a carbide, the upper anti-reflection layer, if present, contains an oxide.

9. The vehicle pane according to claim 6, wherein the blocking layer has a thickness from 10 nm to 50 nm, the lower anti-reflection layer has a thickness from 5 nm to 100 nm, the layer based on a transparent conductive oxide has a thickness from 50 nm to 150 nm, the barrier layer has a thickness from 5 nm to 20 nm, the upper anti-reflection layer, if present, has a thickness from 10 nm to 100 nm.

10. A method for producing a vehicle pane with reduced emissivity and light reflection, comprising: applying an emissivity-reducing coating which comprises at least one layer based on a transparent conductive oxide (TCO), to an exposed interior-side surface of a substrate; and (b) deposited an anti-reflection coating based on nanoporous silicon oxide on the emissivity-reducing coating.

11. The method according to claim 10, wherein the anti-reflection coating is applied in in a sol-gel process, by providing a precursor sol that contains silicon oxide precursors in a solvent, mixing the precursor sol with a pore former, applying the solution obtained to the interior-side surface of a substrate, and condensing the precursor sol.

12. The method according to claim 11, wherein the pore former is removed after condensation of the precursor sol.

13. The method according to claim 12, wherein the pore former is implemented as polymeric nanoparticles, and wherein the removal of the pore former is achieved by a heat treatment at a temperature of at least 400° C.

14. The method according to claim 12, wherein the pore former is implemented as polymeric nanoparticles, and wherein the removal of the pore former is achieved by dissolving with a solvent.

15. A method comprising providing a transportation vehicle for traffic on land, in the air, or on water, with a vehicle pane according to claim 1.

16. The vehicle pane according to claim 3, wherein the pores have a size from 20 nm to 80 nm.

17. The vehicle pane according to claim 4, wherein the anti-reflection coating has a refractive index from 1.25 to 1.35.

18. The vehicle pane according to claim 5, wherein the emissivity-reducing coating consists only of the layer based on a transparent conductive oxide (TCO).

19. The method according to claim 8, wherein the blocking layer contains silicon nitride or silicon carbide, the lower anti-reflection layer contains silicon oxide, the barrier layer contains silicon nitride or silicon carbide, and the upper anti-reflection layer, if present, contains silicon oxide.

20. The method according to claim 9, wherein the blocking layer has a thickness from 20 nm to 40 nm, the lower anti-reflection layer has a thickness from 10 nm to 50 nm, the layer based on a transparent conductive oxide has a thickness from 60 nm to 100 nm, the barrier layer has a thickness from 7 nm to 12 nm, and the upper anti-reflection layer, if present, has a thickness from 30 nm to 70 nm.

Description

[0088] They depict:

[0089] FIG. 1 a cross-section through an embodiment of the pane according to the invention,

[0090] FIG. 2 a cross-section through the substrate with the emissivity-reducing coating and the anti-reflection coating of one embodiment of the pane according to the invention,

[0091] FIG. 3 a cross-section through the substrate with the emissivity-reducing coating and der anti-reflection coating of another embodiment of the pane according to the invention,

[0092] FIG. 4 a cross-section through another embodiment of the pane according to the invention,

[0093] FIG. 1 depicts a cross-section through an embodiment of the pane according to the invention with reduced emissivity and light reflection. The pane is implemented as a laminated pane composed of a substrate 1 and an outer pane 2 that are joined to one another via a thermoplastic intermediate layer 3. The substrate 1 functions as the inner pane of the laminated pane. The laminated pane is, for example, the roof panel of a motor vehicle. The outer pane 2 has an exterior-side surface I and an interior-side surface II. Likewise, the substrate 1 has an exterior-side surface III and an interior-side surface IV. The exterior-side surface I of the outer pane 2 and the interior-side surface IV of the substrate 1 are the exposed surfaces of the laminated pane, wherein, in the installed position, the surface I faces the external environment and the surface IV faces the interior of the vehicle. The substrate 1 and the outer pane 2 are, for example, panes of tinted soda lime glass with a thickness of 2.1 mm in each case. The intermediate layer 3, is, for example, made of a 0.76-mm-thick, tinted film of polyvinyl butyral (PVB).

[0094] An emissivity-reducing coating 10 (low-E coating) is applied on the exposed, interior-side surface IV of the substrate 1. The coating 10 improves the thermal comfort in the interior of the vehicle, by reflecting thermal radiation of the pane as well as portions of the solar radiation when outside temperatures are high and reducing the cooling of the interior when outside temperatures are low. An anti-reflection coating 20 is applied on the emissivity-reducing coating 10. It reduces the light reflection of the surface IV with the emissivity-reducing coating 10 such that, for example, an electronic display in the region of the dashboard is less strongly reflected on the roof panel.

[0095] FIG. 2 depicts an embodiment of the coatings 10, 20 according to the invention on the substrate 1. The emissivity-reducing coating 10 is a sequence of thin layers, which, starting from the substrate 1, consists of the following individual layers: a blocking layer 10.1 against alkali diffusion, a lower anti-reflection layer 10.2, a layer 10.3 based on ITO, a barrier layer 10.4 for regulating oxygen diffusion, and an upper anti-reflection layer 10.5. The individual layers of the coating 10 were deposited by magnetron-enhanced cathodic sputtering.

[0096] The anti-reflection layer 20 is a single layer layer of nanoporous silicon oxide (SiO.sub.2) that was deposited on the emissivity-reducing coating 10 using the sol-gel method. The pore size and density were adjusted by means of pore formers such that the refractive index of the anti-reflection coating is approx. 1.3.

[0097] The materials and layer thicknesses are summarised in Table 1, by way of example.

TABLE-US-00001 TABLE 1 Reference Layer Characters Material Thickness Anti-reflection coating 20  Nanoporous SiO.sub.2 100 nm Upper anti-reflection layer 10.5 10 SiO.sub.2:Al 38 nm Barrier layer 10.4 Si.sub.3N.sub.4:Al 8 nm Electrically conductive 10.3 ITO 68 nm layer Lower anti-reflection layer 10.2 SiO.sub.2:Al 20 nm Blocking layer 10.1 Si.sub.3N.sub.4:Al 25 nm Substrate 1 Soda lime glass, 2.1 mm tinted Intermediate layer 3 PVB 0.76 mm Outer panes 2 Soda lime glass, 2.1 mm tinted

[0098] FIG. 3 depicts another embodiment of the coatings 10, 20 according to the invention on the substrate 1. The emissivity-reducing coating 10 is a single layer 10.3 based on fluorine-doped tin oxide (SnO.sub.2:F), which was applied pyrolytically during the production of the substrate 1 using the float process. Here, the anti-reflection layer 20 is also a single layer of nanoporous silicon oxide (SiO.sub.2), deposited on the emissivity-reducing coating 10 using the sol-gel method. The pore size and density were adjusted by means of pore formers such that the refractive index of the anti-reflection coating is approx. 1.3.

[0099] The materials and layer thicknesses are summarised in Table 2, by way of example.

TABLE-US-00002 TABLE 2 Reference Layer Character Material Thickness Anti-reflection coating 20  Nanoporous SiO.sub.2 140 nm Electrically conductive 10.3 10 SnO.sub.2:F 380 nm layer Substrate 1 Soda lime glass, 3.85 mm tinted

[0100] In the embodiment of Table 1, the pane is implemented as a laminated pane; in the embodiment of Table 2, as a thermally prestressed single glass pane. This is to be understood as merely exemplary. Likewise, it is possible to use the emissivity-reducing coating 10 implemented as a thin layer stack (Table 1) on a single glass pane and the pyrolytic emissivity-reducing coating 10 (Table 2) on a laminated pane.

[0101] FIG. 4 depicts a cross-section through an embodiment of the pane according to the invention with reduced emissivity and light reflection. Substrate 1, outer pane 2, intermediate layer 3, emissivity-reducing coating 10, and anti-reflection coating 20 are implemented as in FIG. 1. In addition, an IR reflective coating 30 is applied on the interior-side surface II of the outer pane. The coating 30 serves as a sun protection coating. It is a thin layer stack comprising multiple silver layers and numerous dielectric layers. Such IR reflecting coatings based on silver are known per se. They reflect solar radiation, in particular in the near IR range, and thereby further improve thermal comfort by reducing the heating of the laminated pane and the transmittance of IR radiation.

EXAMPLES

[0102] Table 3 shows materials and layer thicknesses of two Examples 1 and 2 of the type according to FIG. 2 as well as a Comparative Example 1. The refractive index of the anti-reflection layer 20 is 1.3 in each case. The substrate 1 is a tinted, thermally prestressed soda lime glass pane (light transmittance of 10% at a theoretical thickness of 4 mm), which forms the pane according to the invention as single pane safety glass (ESG).

[0103] The two Examples 1 and 2 according to the invention differ slightly in the layer thicknesses of the individual layers of the emissivity-reducing coating 10. In particular, by adjusting the thickness of the dielectric layers, the optical properties of the pane can be influenced, for example, the reflection colour. The Comparative Example 1 has the same the emissivity-reducing coating 10 as Example 1, but has no anti-reflection coating 20.

TABLE-US-00003 TABLE 3 Thickness Comparative Layer Material Example 1 Example 2 Example 1 20 Nanoporous 100 nm 100 nm — SiO.sub.2 10.5 SiO.sub.2 40 nm 40 nm 40 nm 10.4 Si.sub.3N.sub.4 9 nm 9 nm 9 nm 10.3 ITO 72 nm 72 nm 72 nm 10.2 SiO.sub.2 20 nm 10 nm 20 nm 10.1 Si.sub.3N.sub.4 30 nm 25 nm 30 nm 1 Glass, tinted 3.85 mm 3.85 mm 3.85 mm

[0104] Table 4 shows materials and layer thicknesses of an Example 3 of the type according to FIG. 3 as well as a Comparative Example 2. The refractive index of the anti-reflection layer 20 is 1.3 in each case. The substrate 1 was a tinted soda lime glass pane (light transmittance of 10% at a theoretical thickness of 4 mm). The Comparative Example 2 has the same emissivity-reducing coating 10 as Example 3, but has no anti-reflection coating 20.

TABLE-US-00004 TABLE 4 Thickness Comparative Layer Material Example 3 Example 2 20 Nanoporous 140 nm — SiO.sub.2 10.3 SnO.sub.2:F 380 nm 380 nm 1 Glass, tinted 3.85 mm 3.85 mm

[0105] Table 5 summarises the integral reflection values of the example panes. The values of the reflectance R.sub.L shown were determined by simulation with the software CODE. The reflection values characterise the interior-side light reflection under irradiation with light source A and an observation angle of 8° (R.sub.L(A) 8°) and 60° (R.sub.L(A) 60°), respectively. The integral reflection values R.sub.L(A) 8° and R.sub.L(A) 60° are obtained by integrating the reflection spectrum in the visible spectral range from 380 nm to 780 nm.

TABLE-US-00005 TABLE 5 Compar- Compar- ative ative Example 1 Example 2 Example 1 Example 3 Example 2 R.sub.L(A) 8° 0.6% 1.5% 3.9% 1.8% 7.9% R.sub.L(A) 60° 2.2% 2.0% 9.5% 2.0% 12.6%

[0106] It can be seen that the light reflection is significantly reduced by the anti-reflection coating 20 according to the invention. In particular, the value R.sub.L(A) 60° enables a conclusion about the extent to which reflections on the roof panel are perceived as disturbing by the occupants of the back seat. It was also shown that the anti-reflection coating 20 adheres well to the emissivity-reducing coating 10 and has sufficient long-term stability for use in a motor vehicle.

[0107] Table 6 shows materials and layer thicknesses of another Example 4 according to the invention. The embodiment of Example 4 is similar to that of Examples 1 and 2. The emissivity-reducing coating 10 has, in contrast thereto, no upper anti-reflection layer 10.5, but consists only of the blocking layer 10.1 against alkali diffusion, the lower anti-reflection layer 10.2, the layer 10.3 based on ITO, and the barrier layer 10.4 for regulating oxygen diffusion. Here, again, the individual layers of the coating 10 were deposited by magnetron-enhanced cathodic sputtering. The anti-reflection layer 20 is, again, a single layer of nanoporous silicon oxide (SiO.sub.2) that was deposited on the emissivity-reducing coating 10 using the sol-gel method. The pore size and density were adjusted by means of pore formers such that the refractive index of the anti-reflection coating is approx. 1.3.

[0108] Table 6 also shows the materials and layer thicknesses of another Comparative Example 3. Comparative Example 3 does not have a nanoporous anti-reflection coating 20 according to the invention. Compared to Examples 1 and 2 and Comparative Example 1, the thickness of the upper anti-reflection layer 10.5 is significantly increased such that the person skilled in the art could assume from it that the upper anti-reflection layer 10.5 at least partially fulfils the function of the anti-reflection coating 20. Alternatively, Comparative Example 3 can be used for comparison with Example 4, with the emissivity-reducing coating 10 designed identically and the anti-reflection coating 20 according to the invention of Example 4 being replaced by an alternative anti-reflection coating, which was deposited by magnetron-enhanced cathodic sputtering.

TABLE-US-00006 TABLE 6 Thickness Comparative Layer Material Example 4 Example 3 20 Nanoporous 100 nm SiO.sub.2 10.5 SiO.sub.2 — 140 nm 10.4 Si.sub.3N.sub.4 9 nm 9 nm 10.3 ITO 72 nm 72 nm 10.2 SiO.sub.2 20 nm 20 nm 10.1 Si.sub.3N.sub.4 30 nm 30 nm 1 Glass, tinted 3.85 mm 3.85 mm

[0109] Table 7 summarises the integral reflection values of Example 4 and Comparative Example 3 (analogous to Table 5).

TABLE-US-00007 TABLE 7 Comparative Example 4 Example 3 R.sub.L(A) 8° 0.1% 4.2% R.sub.L(A) 60° 3.5% 7.3%

[0110] It can be seen that with Example 4, reflection values are achieved that are in a range similar to those of Examples 1-3. It is also possible to dispense with the upper anti-reflection layer 10.5 of the emissivity-reducing coating 10—its function is taken over, as it were, by the anti-reflection coating 20.

[0111] Likewise, it can be seen that with Comparative Example 3, significantly higher reflection values are achieved than with the examples. This is true in particular for the observation angle of 60°. The angle-dependence of the reflection behaviour is thus greater without the nanoporous anti-reflection coating 20. In addition, the deposition of such a thick SiO.sub.2 layer by cathodic sputtering is costly and time-consuming.

LIST OF REFERENCE CHARACTERS

[0112] (1) substrate [0113] (2) outer pane [0114] (3) thermoplastic intermediate layer [0115] (10) emissivity-reducing coating [0116] (10.1) blocking layer against alkali diffusion [0117] (10.2) lower anti-reflection layer [0118] (10.3) layer based on a transparent conductive oxide (TCO) [0119] (10.4) barrier layer to regulate oxygen diffusion [0120] (10.5) upper anti-reflection layer [0121] (20) anti-reflection coating [0122] (30) sun protection coating [0123] (I) exterior-side surface of the outer pane 2 [0124] (II) interior-side surface of the outer pane 2 [0125] (III) exterior-side surface of the substrate 1 [0126] (IV) interior-side surface of the substrate 1