DECORATIVE GLASS PANEL

Abstract

The invention relates to an almost opaque decorative glass panel comprising a substrate made of a vitreous material bearing a multilayer stack including at least one light-absorbing functional layer and transparent dielectric coatings such that the light-absorbing functional layer is enclosed between dielectric coatings. The light-absorbing functional layer has a geometric thickness comprised between 25 and 140 nm, and an extinction coefficient k of at least 1.8. The multilayer stack in addition comprises at least one attenuating layer placed between the substrate and the light-absorbing functional layer, having a thickness comprised between 1 and 50 nm, having a refractive index n higher than 1 and an extinction coefficient k of at least 0.5. Furthermore, a transparent dielectric coating the optical thickness of which is comprised between 30 and 160 nm, and the refractive index n of which is higher than 1.5, is placed adjacent to the attenuating layer on the side opposite the light-absorbing functional layer. The invention provides a decorative panel offering a pleasant aesthetic effect.

Claims

1. An almost opaque decorative glass panel, comprising a substrate made of vitreous material bearing a multilayer stack including at least one light-absorbent functional layer and transparent dielectric coatings such that the light-absorbent functional layer is enclosed between dielectric coatings, wherein: the light-absorbent functional layer has a geometric thickness between 15 and 140 nm, an attenuation coefficient k of at least 1.8 and a product of the attenuation coefficient k by the layer thickness in nanometers of at least 91; the multilayer stack in addition comprises at least one attenuating layer having a thickness between 1 and 50 nm and having a refractive index n higher than 1 and an attenuation coefficient k of at least 0.5; a transparent dielectric coating the optical thickness of which is between 30 and 160 nm and the refractive index n of which is higher than 1.5, unless it makes contact with air, is placed adjacent the attenuating layer on the side opposite the light-absorbent functional layer.

2. The decorative panel according to claim 1, wherein the light-absorbent functional layer is a layer of metallic character.

3. The decorative panel according to claim 1, wherein the attenuating layer is a layer of metallic character.

4. The decorative panel according to claim 1, wherein the attenuating layer is separated from the light-absorbent functional layer by a transparent dielectric coating.

5. The decorative substrate according to claim 1, wherein the geometric thickness of the light-absorbent functional layer is at most 88 nm.

6. The decorative panel according to claim 1, wherein the geometric thickness of the light-absorbent functional layer is 28 nm or more.

7. The decorative panel according to claim 1, wherein the geometric thickness of the attenuating layer is 30 nm or less.

8. The decorative panel according to claim 1, wherein the product of the attenuation coefficient k by the refractive index n and by the geometric thickness, expressed in nm, of the attenuating layer is higher than 35.

9. The decorative panel according to claim 1, wherein the optical thickness of said dielectric coating placed adjacent the attenuating layer on the side opposite the light-absorbent functional layer is between 50 and 140 nm.

10. The decorative panel according to claim 1, wherein: the geometric thickness of the light-absorbent functional layer is between 25 and 70 nm; the geometric thickness of the attenuating layer is between 1 and 15 nm; and the optical thickness of said dielectric coating placed adjacent the attenuating layer on the side opposite the light-absorbent functional layer is between 40 and 160 nm.

11. The decorative panel according to claim 1, wherein the light-absorbent functional layer and/or the attenuating layer is/are formed from an alloy based on Ni, Cr, Zr or NiCr.

12. The decorative panel according to claim 11, wherein the light-absorbent functional layer and/or said attenuating layer is/are based on an alloy from the group NiCr, NiCrW, NbZr and CrZr.

13. The decorative panel according to claim 1, wherein at least the transparent dielectric coatings external with respect to the stack in its entirety are based on aluminum nitride or silicon nitride.

14. The decorative panel according to claim 1, wherein a second attenuating layer, having a thickness between 1 and 50 nm, having a refractive index n higher than 1 and an attenuation coefficient k of at least 0.5, and an additional transparent dielectric coating the optical thickness of which is between 30 and 160 nm and the refractive index n of which is higher than 1.5, unless it makes contact with air, are added on the other side of the light-absorbent functional layer with respect to the first attenuating layer, so that this additional transparent dielectric coating is on the other side of the second attenuating layer with respect to the light-absorbent functional layer.

15. A glass panel, comprising a substrate made of vitreous material bearing a multilayer stack including at least one light-absorbent functional layer and one attenuating layer, which layers are flanked by transparent dielectric coatings, wherein the glass panel has a light transmission of 2% or less, a light reflection, observed from the side of the attenuating layer, of 6.5% or less, and a neutral hue in reflection observed from the same side.

16. The glass panel according to claim 15, wherein the light-absorbent functional layer and the attenuating layer are formed from an alloy based on Ni, Cr, Zr or W.

17. The glass panel according to claim 16, wherein the light-absorbent functional layer and the attenuating layer are based on an alloy from the group NiCr, NiCrW and CrZr.

18. The glass panel according to claim 15, wherein the transparent dielectric coatings are based on aluminum nitride or silicon nitride.

19. The glass panel according to claim 15, wherein the a* and b* colour coordinates observed in reflection on the attenuating-layer side are both lower than 4 in absolute value.

20. The glass panel according to claim 15, wherein the light reflection observed from at least one of the sides of the panel is 5.2% or less.

21. A laminated panel, comprising a decorative panel according to claim 1, with which another glass sheet is associated by way of an adhesive thermoplastic.

22. A laminated panel, comprising a glass panel according to claim 14, with which another glass sheet is associated by way of an adhesive thermoplastic.

Description

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0059] The invention will now be described, merely by way of illustration, using the following exemplary embodiments.

Comparative examples C1 to C4:

[0060] In table I below, the four first examples not according to the invention included only a single metal layer and either two transparent dielectric coatings or just one (the case for example C3). The corresponding optical properties are indicated in table I. The light transmission (T.sub.L) in % and light reflection (R.sub.L) in % were measured with CIE-standard illuminant D65, 2. The CIE, L*, a*, b* color coordinates were measured with illuminant D65, 10. The light reflection R.sub.LG and the L*.sub.RG, a*.sub.RG, b*.sub.RG color coordinates were observed in reflection from the side of the substrate.

[0061] The multilayer stacks indicated in the table were deposited on an ordinary clear soda-lime glass sheet of 4 mm thickness by low-pressure magnetron cathode sputtering in a magnetron. The light-absorbent NiCrW metal layer was deposited in a neutral argon atmosphere using a metal target of an NiCrW alloy composed of 50% by weight NiCr (nickel chromium in a proportion of 80/20, respectively) and 50% by weight tungsten. The Si.sub.3N.sub.4 nitride dielectric layers were deposited using a metallic silicon target doped with 4% aluminum, in a reactive argon and nitrogen atmosphere. The designation Si.sub.3N.sub.4 does not mean that the material was perfectly stoichiometric and it may have been slightly substoichiometric in nitrogen or slightly oxidized. The same went for the other nitrides. The same likewise went for the oxides (SiO.sub.2, TiO.sub.2), which were possibly also slightly substoichiometric in oxygen or slightly nitrified.

[0062] In the tables, the layers are shown from left to right in the order that they were deposited on the glass substrate. The indicated thicknesses are geometric thicknesses in nm.

TABLE-US-00003 TABLE I (comparative examples): Ex. Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.L L* a* b* C1 62.5 4.5 6.3 41 5 27.16 0.7 0.1 C2 60 3 50 64 12 41.96 4.7 0.3 C3 50 50 1.7 45 73 0.2 4.8 C4 56.7 50 50 2.2 25.5 57.7 3.1 0.8

[0063] Examples C1 and C2 have a much too high light transmission for the intended application and were therefore unsuitable. Example C1 of course allows a low light reflection with a neutral hue to be obtained. However, apart from the fact that the light transmission was much too high, the second dielectric coating was also much too thin to obtain a durable product. The mechanical and chemical protection afforded was insufficient.

[0064] Examples C3 and C4 had a very low light transmission suitable for the intended application, but they had much too high a light reflection and were therefore unsuitable.

EXAMPLES 1 TO 24 ACCORDING TO THE INVENTION AND COMPARATIVE EXAMPLES C5 TO C8

[0065] In table II below, examples according to the invention are collated in the same format as the comparative examples in table I. Two comparative examples C5 to C8 are also shown. The layers were deposited under the same conditions and using the same technique, i.e. low-pressure magnetron cathode sputtering in a magnetron. The composition of the NiCrW layers was the same as in the comparative examples. The Al, Cu, Cr and Ti metallic layers were also deposited in a neutral argon atmosphere, using a metallic target made of the corresponding material. The TiN, CrN, TaN and ZrN nitride layers were deposited using a metallic target of the corresponding material, in a reactive argon and nitrogen atmosphere. The TiO.sub.2 oxide layers were deposited using a ceramic TiOx target, in a reactive argon and oxygen atmosphere. The SiO.sub.2 layers were deposited using a silicon target doped with 4% aluminum, in an oxidizing reactive argon and oxygen atmosphere. The SiON layer was deposited in a reactive argon and nitrogen atmosphere containing a little oxygen. The AZO layer was deposited using a ceramic aluminum-doped zinc-oxide target, in a neutral atmosphere. These multilayer stacks were also deposited on an ordinary clear soda-lime glass sheet of 4 mm thickness.

[0066] The mean attenuation coefficients k and refractive indices n, which were calculated as indicated above over the whole of the visible spectrum extending from 350 nm to 750 nm, are given in table III below.

[0067] The light transmission (T.sub.L in % and the light reflection (R.sub.Lin % were measured with CIE-standard illuminant D65, 2. The CIE L*, a* and b* colour color coordinates were measured with illuminant D65, 10. The light reflection R.sub.LG and the L*.sub.RG, a*.sub.RG, b*.sub.RG color coordinates were observed in reflection from the side of the substrate. The light reflection R.sub.LC and the L*.sub.RC, a*.sub.Rc, b*.sub.Rc color coordinates were observed in reflection from the side of the multilayer stack.

TABLE-US-00004 TABLE II (examples according to the invention and comparative examples C5 to C8): Ex. Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 1 56.3 7.2 50 50 50 0.5 4.3 24.7 0.1 0.3 2 43.9 9.3 47.5 36.9 30 1 6 29.8 3 3 3 33.7 7.6 49.2 39.1 30 1 6 29.8 3 3 4 51.6 5 52.2 44 32.5 1 6 29.8 3 3 5 60 5.3 53.4 44.3 36.6 1 6 29.8 2.8 3 6 56.4 7.1 50.2 63.8 50 0.2 4.3 24.7 0 0.3 Ex. Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 Al Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 7 58.8 8.7 52.3 34 50 0.2 4.4 25 0.1 0.1 Ex. Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 Ti Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 8 56.6 6.9 42 94.1 50 0.2 4.3 24.7 0 0.3 Ex. Si.sub.3N.sub.4 Ti Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 9 49.7 14.5 60.9 64.8 50 0.2 4.4 25 0.1 0.1 Ex. Si.sub.3N.sub.4 Al Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG C5 47.9 3.4 81.9 66.8 50 0.4 10.6 38.9 4.2 1.7 Ex. Si.sub.3N.sub.4 TiN Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 10 45 29.1 37.4 64.6 50 0.2 4.9 26.4 0.4 0.2 Ex. Si.sub.3N.sub.4 ZrN Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 11 39.8 25 0 75.5 50 0.3 6 29.7 0 0.5 Ex. TiO.sub.2 NiCrW Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 12 43.6 10.4 57.8 61.5 50 0.2 4.9 26.6 0.3 0.2 Ex. NiCrW Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG C6 5.1 49.4 59.7 50 0.4 6.7 31.2 5.9 0.5 Ex. SiON NiCrW Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 13 69.3 4.1 51.4 67.5 50 0.2 5 26.9 2.6 0.2 Ex. Si.sub.3N.sub.4 NiCrW TiO.sub.2 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 14 56.9 5.8 37.4 68.4 50 0.2 4.6 25.5 0.3 0.1 Ex. TiO.sub.2 NiCrW TiO.sub.2 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 15 42.2 9.9 40.5 64.4 50 0.2 4.7 25.8 0.1 0.2 Ex. Si.sub.3N.sub.4 NiCrW SiO.sub.2 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 16 54.3 8.2 80.1 55.6 50 0.2 4.3 24.7 0 0.4 Ex. Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG/ L*.sub.RG/ a*.sub.RG/ b*.sub.RG/ R.sub.LC L*.sub.RC a*.sub.RC b*.sub.RC 17 30 56.6 47.6 8.3 44.6 0.2 31.9/4 63/23.8 0.3/0 10.5/0.1 Ex. Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 CrN Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 18 55.3 5.9 49.6 131.5 50 0.2 4.3 24.6 0 0.5 Ex. Si.sub.3N.sub.4 W Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 19 55.9 9 39.5 64.6 50 0.2 4.3 24.8 0 0.3 Ex. Si.sub.3N.sub.4 Cu Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG C7 40.8 9.5 78.5 69.1 50 0.3 13.5 43.5 11.8 5 Ex. Si.sub.3N.sub.4 Cr Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 20 50.1 10.1 68.4 65.5 50 0.2 4.5 25.4 0 0.2 Ex. Si.sub.3N.sub.4 CrN Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*R.sub.G 21 46.7 15.9 27.4 65.9 50 0.2 4.3 24.7 0 0.2 Ex. Si.sub.3N.sub.4 AZO Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG C8 55.7 161 126 70.7 50 0.2 8.9 35.6 0.8 0.3 Ex. Si.sub.3N.sub.4 TaN Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 22 51 7.9 9.9 77.4 50 0.2 5.3 27.6 1 0.5 Ex. TiO.sub.2 NiCrW Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 23 46.3 10.4 57.8 61.5 50 0.2 4.9 26.6 0.3 0.2 Ex. SiON NiCrW Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG 24 69.3 4.1 51.4 67.5 50 0.2 5 26.9 2.6 0.2

[0068] Except for example 17, the attenuating layer is always in the third column of the table and the light-absorbent functional layer always in the fifth column of the table. In example 17, these two layers were inverted: the attenuating layer is in the fifth column and the light-absorbent functional layer is in the third column.

[0069] It will be noted that, in the examples according to the invention, a truly very low light transmission was obtained, the panel being almost opaque, and that the light reflection observed from the side of the substrate was also very low. Specifically, taking into account the reflection of light from the external surface of the glass sheet, which was about 4%, this meant that the light reflection of the multilayer stack was at most 2% and indeed lower than 1% in most of the examples. In addition, the hue in reflection on the substrate side was relatively neutral, thereby giving the panel a very aesthetic absorbent black appearance.

[0070] In variants of example 1, the thickness of the light-absorbent functional layer, in the fifth column of the table, was changed to 40 nm and to 65 nm, instead of 50 nm, thereby giving a light transmission (T.sub.L) of 1% and 0.2%, respectively, all other properties remaining the same.

[0071] In the comparative examples C5 and C7, the attenuating layers, which were made of aluminum and of copper, respectively, had refractive indices lower than 1 (namely 0.9). It may be seen that the substrate-side light reflection was higher than 10%, this being unsatisfactory. In addition, the hue was riot neutral and had an unacceptable red appearance.

[0072] In the comparative example C6, there was no dielectric coating between the substrate and the attenuating layer, having a refractive index higher than 1.5. It may be seen that the substrate-side light reflection was high and that the value of a* was also high. This was unsatisfactory because the aesthetic appearance that resulted was unsuitable.

[0073] In the comparative example C8, the attenuating layer was made of AZO the attenuation coefficient k of which was only 0.2 and therefore lower than 0.5. Despite an increase in the thickness of the dielectric interlayer between the light-absorbent functional layer and the attenuating layer, the substrate-side light reflection was higher than 6.5%. Therefore, a low light reflection was riot obtained. In fact, AZO, despite having a very low absorption, is too transparent to be a suitable material for the attenuating layer: it rather forms a transparent dielectric layer that may be used as such, just like other transparent dielectric layers.

[0074] In contrast, it may be seen that with an attenuating layer formed by ZrN that has an attenuation coefficient k that is higher than 0.5 but nonetheless relatively low (1.1), a substrate-side light reflection of only 5.3 was obtained.

[0075] The attenuation coefficients and the refractive indices of the various materials such as used in the examples are given by way of indication in the following table:

TABLE-US-00005 TABLE III Material n (350-750 nm) k (350-750 nm) NiCrW 3.5 3.6 SiN 2.0 0.0 Al 0.9 6.1 Ti 1.9 2.6 Cu 0.9 3.2 TiN 2.1 1.4 AZO 2.7 0.2 Cr 1.8 3.6 CrN 3.1 1.8 TaN 5.2 1.1 w 3.5 2.7 ZrN 3.2 0.5 TiO2 2.6 0.0 SiO2 1.5 0.0

[0076] In example 17, the respective positions with respect to the substrate of the light-absorbent functional layer and the attenuating layer were inverted. It may be seen in this example that it was the stack-side light reflection that was very low with a neutral hue of black appearance. This panel according to example 17 was intended to be seen from the stack side and not from the substrate side as in examples 1-16. The stack is, for example, intended to be positioned in P1 (position 1 starting from the observer), or in P3 if it is placed in a laminated panel or in a double panel with a central space.

EXAMPLE 25 ACCORDING TO THE INVENTION

[0077] Example 25 related to a decorative panel intended to be observable from both sides and therefore either from the substrate side or from the multilayer-stack side. In this case, a second attenuating layer is placed on the other side of the light-absorbent functional layer with respect to the first attenuating layer. The structure of the stack is given in table IV:

TABLE-US-00006 TABLE IV Ex. Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 NiCrW Si.sub.3N.sub.4 25 56.7 7.2 50.8 43.4 44.8 8.4 48.3

[0078] The light-absorbent functional layer is in the fifth column and the attenuating layers are in the third and seventh columns.

[0079] The optical properties that resulted are given in table V.

TABLE-US-00007 TABLE V Ex. T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG R.sub.LC L*.sub.RC a*.sub.RC b*.sub.RC 25 0.2 4.3 24.8 0 0.3 4 23.7 0 0

[0080] It may be seen that for example 25 according to the invention, a very low light reflection and a neutral hue were obtained both on the stack side and on the substrate side.

[0081] Needless to say, the invention is not limited to the implementation examples mentioned in the present description.

EXAMPLES 26 AND 27 ACCORDING TO THE INVENTION

[0082] As table VI shows, in example 26 the dielectric coatings were made of SnO.sub.2, and the attenuating layers of NiCr; and in example 27, the dielectric coatings were made of Zn.sub.2SnO.sub.4 and the attenuating layers of NiCr.

TABLE-US-00008 TABLE VI Ex. SnO.sub.2 NiCr SnO.sub.2 NiCr SnO.sub.2 26 56.7 7.2 50.8 43.4 44.8 Ex. Zn.sub.2SnO.sub.4 NiCr ZSO.sub.5 NiCr Zn.sub.2SnO.sub.4 27 57.8 7.4 56.8 50.0 50.0

[0083] As may be seen in table VII below, with examples 26 and 27 according to the invention a truly very low light transmission was also obtained, the panel being almost opaque, and the light reflection observed from the side of the substrate was also very low. Specifically, taking into account the reflection of light from the external surface of the glass sheet, which is about 4%, this means that the light reflection of the multilayer stack was lower than 1%. In addition, the hue in reflection on the substrate side was relatively neutral, thereby giving the panel a very aesthetic absorbent black appearance.

TABLE-US-00009 TABLE VII Ex. T.sub.L R.sub.LG L*.sub.RG a*.sub.RG b*.sub.RG R.sub.LC L*.sub.RC a*.sub.RC b*.sub.RC 26 0.7 4.8 26.1 0.3 0.3 10.1 39.0 13.3 27.8 27 0.6 4.5 25.3 0.1 0.1 15.8 46.6 15.3 1.1