Pane with thermal radiation reflecting coating

Abstract

The present invention relates to a pane with thermal radiation reflecting coating, comprising at least one substrate (1) and at least one thermal radiation reflecting coating (2) at least on the interior-side surface of the substrate (1), wherein the pane has transmittance in the visible spectral range of less than 5%, and the coating (2), proceeding from the substrate (1), comprises at least: one adhesive layer (3) that contains at least one material with a refractive index of less than 1.8, one functional layer (4) that contains at least one transparent, electrically conductive oxide, one optically high-refractive-index layer (5) that contains at least one material with a refractive index greater than or equal to 1.8, and one optically low-refractive-index layer (6) that contains at least one material with a refractive index of less than 1.8.

Claims

1. An article comprising a pane comprising a thermal radiation reflecting coating that separates an interior of the article from an external environment, wherein the article is selected from the group consisting of a building, an apparatus for land transportation, an apparatus for air transportation, and an apparatus for water transportation, wherein the pane comprising at least one substrate and at least one thermal radiation reflecting coating situated at least on an interior-side surface of the substrate, wherein the pane has a transmittance in the visible spectral range of less than 5%; and wherein the coating, in order proceeding from the substrate, comprises at least one adhesive layer comprising at least one material with a refractive index of less than 1.8, one functional layer comprising at least one transparent, electrically conductive oxide, one optically high-refractive-index layer comprising at least one material with a refractive index greater than or equal to 1.8, and one optically low-refractive-index layer comprising at least one material with a refractive index of less than 1.8.

2. The article of claim 1, wherein the pane is a composite pane, and wherein the substrate is bonded to a cover pane via at least one thermoplastic intermediate layer.

3. The article of claim 1, wherein the pane has transmittance in the visible spectral range of less than 4%.

4. The article of claim 1, wherein the adhesive layer of the pane comprises at least one oxide.

5. The article of claim 1, wherein the adhesive layer of the pane has a thickness from 10 nm to 150 nm.

6. The article of claim 1, wherein the functional layer of the pane comprises at least fluorine-doped tin oxide, antimony-doped tin oxide, indium tin oxide, or a mixture thereof.

7. The article of claim 1, wherein the functional layer of the pane has a thickness from 50 nm to 150 nm.

8. The article of claim 1, wherein the optically high-refractive-index layer of the pane comprises at least one oxide or nitride.

9. The article of claim 1, wherein the optically high-refractive-index layer of the pane has a thickness of at least 1 nm and of less than 20 nm.

10. The article of claim 1, wherein the optically low-refractive-index layer of the pane comprises at least one oxide.

11. The article of claim 1, wherein the optically low-refractive-index layer of the pane has a thickness from 40 nm to 130 nm.

12. The article of claim 1, wherein a cover layer comprising at least one oxide is arranged above the optically low-refractive-index layer of the pane.

13. The article of claim 1, wherein a ratio of an interior-side transmittance level T.sub.L in the visible spectral range to an interior-side reflection level R.sub.L in the visible spectral range, T.sub.L/R.sub.L, of the pane is greater than or equal to 0.6.

14. The article of claim 1, which is a rear window, side window, and/or roof panel of a train, ship, or motor vehicle.

15. A method for producing the article of claim 1, the method comprising applying at least (a) the adhesive layer, (b) the functional layer, (c) the optically high-refractive-index layer, and (d) the optically low-refractive-index layer in succession on the interior-side surface of the substrate, to form the pane; and inserting the pane in an opening of the article.

Description

(1) The invention is explained in detail in the following with reference to drawings and exemplary embodiments. The drawings are schematic representations and not true to scale. The drawings in no way restrict the invention.

(2) They depict:

(3) FIG. 1 a cross-section through an embodiment of the pane according to the invention with thermal radiation reflecting coating,

(4) FIG. 2 a cross-section through another embodiment of the pane according to the invention with thermal radiation reflecting coating,

(5) FIG. 3 a cross-section through another embodiment of the pane according to the invention with thermal radiation reflecting coating,

(6) FIG. 4 a diagram of the ratio T.sub.L/R.sub.L as a function of the thickness of the adhesive layer,

(7) FIG. 5 a diagram of the ratio T.sub.L/R.sub.L as a function of the thickness of the functional layer,

(8) FIG. 6 a diagram of the ratio T.sub.L/R.sub.L as a function of the thickness of the optically high-refractive-index layer,

(9) FIG. 7 a diagram of the ratio T.sub.L/R.sub.L as a function of the thickness of the optically low-refractive-index layer, and

(10) FIG. 8 a detailed flow chart of an embodiment of the method according to the invention.

(11) FIG. 1 depicts a cross-section through an embodiment of the pane according to the invention with the substrate 1 and the thermal radiation reflecting coating 2. The substrate 1 contains, for example, tinted soda lime glass and has a thickness of 6 mm. The coating 2 comprises an adhesive layer 3, a functional layer 4, an optically high-refractive-index layer 5, and an optically low-refractive-index layer 6. The layers are arranged in the order indicated with increasing distance from the substrate 1.

(12) The adhesive layer 3 is made, for example, from aluminum-doped silicon oxide and has a thickness of 30 nm. The functional layer 4 is made, for example, from indium tin oxide (ITO) and has a thickness of 130 nm. The optically high-refractive-index layer 5 is made, for example, from aluminum-doped silicon nitride and has a thickness of 5 nm. The optically low-refractive-index layer 6 is made, for example, from aluminum-doped silicon oxide and has a thickness of 70 nm auf.

(13) The individual layers of the coating 2 were deposited using magnetically enhanced cathodic sputtering. The target for the deposition of the adhesive layer 3 and the optically low-refractive-index layer 6 contained 92 wt.-% silicon and 8 wt.-% aluminum. The deposition was done under addition of oxygen as reaction gas during the cathodic sputtering. The target for the deposition of the functional layer 4 contained 90 wt.-% indium oxide and 10 wt.-% tin oxide. The deposition was done under an argon protective gas atmosphere with an oxygen fraction of less than 1%. The target for the deposition of the optically high-refractive-index layer 5 contained 92 wt.-% silicon and 8 wt.-% aluminum. The deposition was done under addition of nitrogen as reaction gas during the cathodic sputtering.

(14) FIG. 2 depicts a cross-section through another embodiment of the pane according to the invention with the substrate 1 and the thermal radiation reflecting coating 2. The coating 2 is configured as in FIG. 1 with the adhesive layer 3, the functional layer 4, the optically high-refractive-index layer 5, and the optically low-refractive-index layer 6. A cover layer 7 is arranged above the coating 2. The cover layer contains TiO.sub.2 and has a thickness of 10 nm. By means of the cover layer, the coating 2 is advantageously protected against mechanical damage, in particular against scratches.

(15) FIG. 3 depicts a cross-section through a pane according to the invention with thermal radiation reflecting coating 2 as a composite pane. The substrate 1 is bonded to a cover pane 8 via a thermoplastic intermediate layer 9. The composite pane is intended as a roof panel for a motor vehicle. The composite pane is curved as is customary for panes in the automotive sector. In the installed position of the composite pane, the cover pane 8 faces the outside environment and the substrate 1 faces the vehicle interior. The interior-side surface of the substrate 1, which faces away from the cover pane 8 and the thermoplastic intermediate layer 9, is provided with the coating 2 according to the invention. The substrate 1 and the cover pane 8 are made of soda lime glass and have, in each case, a thickness of 2.1 mm. The thermoplastic intermediate layer 9 contains tinted polyvinyl butyral (PVB) and has a thickness of 0.76 mm.

(16) The substrate 1, the cover pane 8, and the thermoplastic intermediate layer 9 are tinted. The substrate 1 and the cover pane 9 have, for example, in each case, transmittance in the visible spectral range of 27%; the thermoplastic intermediate layer 8 has, for example, transmittance of 23%. The composite pane has, without the coating 2, interior-side transmittance T.sub.L in the visible spectral range of 2.3% and interior-side reflection R.sub.L of 4.4% auf. The ratio T.sub.L/R.sub.L is 0.5, without the coating 2. The thermal radiation reflecting coating 2 according to the invention surprisingly improves not only the thermal comfort in the interior of the motor vehicle, but also acts as an antireflection coating. The interior-side reflection R.sub.L is reduced to 2.0% by the coating 2. The ratio T.sub.L/R.sub.L is increased to 1.1 by the coating 2. As a result of the coating 2, individuals in the motor vehicle interior are able to better perceive the external environment and are less bothered by reflections.

(17) FIG. 4, FIG. 5, FIG. 6, and FIG. 7 show results of simulations of the ratio T.sub.L/R.sub.L of the transmittance level T.sub.L in the visible spectral range to the reflection level R.sub.L in the visible spectral range. The greater the ratio T.sub.L/R.sub.L, the less pronounced the bothersome interior-side reflections and the more pleasant the optical impression of the pane. FIG. 4 presents the ratio T.sub.L/R.sub.L as a function of the thickness of the adhesive layer 3. FIG. 5 presents the ratio T.sub.L/R.sub.L as a function of the thickness of the functional layer 4. FIG. 6 presents the ratio T.sub.L/R.sub.L as a function of the thickness of the optically high-refractive-index layer 5. FIG. 7 presents the ratio T.sub.L/R.sub.L as a function of the thickness of the optically low-refractive-index layer 6.

(18) The simulations assume the basic layer structure, whose layer sequence is presented with materials and layer thicknesses in Table 1. In each case, one of the layer thicknesses was varied; the remaining layer thicknesses corresponded to the values in Table 1. The aggregate of substrate 1, thermoplastic intermediate layer 8, and cover glass 9 had, without the coating 2, transmittance T.sub.L of roughly 4.2%.

(19) By way of comparison, the figures present the ratio T.sub.L/R.sub.L without the coating 2. The values are indicated in each case for two different angles of observation . The angle is the angle between the direction of observation (connecting line between observer and pane) and the surface normal of the pane.

(20) TABLE-US-00001 TABLE 1 Reference Character Material Thickness 6 2 SiO.sub.2:Al 70 nm 5 Si.sub.3N.sub.4:Al 10 nm 4 ITO 130 nm 3 SiO.sub.2:Al 30 nm 1 Glass 2.1 mm 8 PVB 0.76 mm 9 Glass 3.15 mm

(21) The absolute values for the ratio T.sub.L/R.sub.L depend on the transmittance through the pane. A lower transmittance with unchanged reflection results in a lower ratio T.sub.L/R.sub.L. This means that the same coating 2 on a pane with lower transmittance yields a lower ratio T.sub.L/R.sub.L than on a pane with higher transmittance. The qualitative dependence of the ratio T.sub.L/R.sub.L is, however, independent of the transmittance of the pane and can be found in the figures.

(22) From FIG. 4, it is discernible that the ratio T.sub.L/R.sub.L has no clear dependence on the thickness of the adhesive layer 3. The thickness of the adhesive layer 3 thus hardly influences the antireflecting properties of the coating 2. The thickness of the adhesive layer 3 can, consequently, be selected on the basis of the adhesion-promoting properties and the barrier action against diffusing ions. It has been demonstrated that particularly good results are obtained with an adhesive layer with a thickness from 10 nm to 150 nm, preferably from 15 nm to 50 nm.

(23) From FIG. 5, it is discernible that the thickness of the functional layer 4 has a clear influence on the antireflecting properties of the coating 2 and, thus, on the ratio T.sub.L/R.sub.L. The maximum for the ratio T.sub.L/R.sub.L is obtained at a thickness of roughly 100 nm. In order to improve the thermal radiation reflecting action, a thicker functional layer 4 can, however, be desirable. It has been demonstrated that for thicknesses of the functional layer 4 from 50 nm to 150 nm, preferably from 60 nm to 140 nm, particularly preferably from 70 nm to 130 nm, a good compromise between the ratio T.sub.L/R.sub.L and the thermal radiation reflecting action is achieved.

(24) From FIG. 6, it is discernible that the thickness of the optically high-refractive-index layer 5 has a clear influence on the antireflecting properties of the coating 2 and, thus, on the ratio T.sub.L/R.sub.L. The ratio T.sub.L/R.sub.L becomes larger the thinner the optically high-refractive-index layer 5 is implemented. With a thickness of less than 20 nm, the ratio T.sub.L/R.sub.L is larger than with the pane without coating 2. Particularly good results are obtained for a thickness of the optically high-refractive-index layer 5 of less than 12 nm, preferably of less than 10 nm, particularly preferably of less than 8 nm. However, for the optically high-refractive-index layer 5 to be able to effectively protect the functional layer 4 against corrosion and oxidation, it should have a thickness of at least 1 nm, preferably at least 2 nm.

(25) From FIG. 7, it is discernible that the thickness of the optically low-refractive-index layer 6 has a clear influence on the antireflecting properties of the coating 2 and, thus, on the ratio T.sub.L/R.sub.L. With a thickness of roughly 40 nm to 130 nm, the ratio T.sub.L/R.sub.L is greater than with the pane without coating 2. Particularly good results are obtained for a thickness of the optically low-refractive-index layer 6 from 50 nm to 120 nm, preferably from 60 nm to 110 nm, particularly preferably from 70 nm to 100 nm.

(26) By means of the coating 2 according to the invention, not only a thermal radiation reflecting action is obtained, but also an antireflecting action. When the coating 2 is applied on the pane with low light transmittance, it reduces bothersome and irritating interior-side reflections. The antireflecting action is even more pronounced with oblique light incidence. These results were unexpected and surprising for the person skilled in the art.

(27) FIG. 8 depicts a flowchart of an exemplary embodiment of the method according to the invention for producing a pane with thermal radiation reflecting coating 2.

LIST OF REFERENCE CHARACTERS

(28) (1) substrate (2) thermal radiation reflecting coating (3) adhesive layer (4) functional layer (5) optically high-refractive-index layer (6) optically low-refractive-index layer (7) cover layer (8) cover pane (9) thermoplastic intermediate layer