GLAZING INCLUDING A STACK OF THIN LAYERS

Abstract

A material includes a transparent substrate coated with a stack of thin layers including a silver-based functional metal layer and two dielectric coatings, wherein a lower dielectric coating located below a silver-based functional layer includes a high-index layer based on metal oxide, an antidiffusion layer based on silicon and/or on aluminum, at least one oxide-based layer located above the antidiffusion layer and exhibiting a different composition from the antidiffusion layer, such as a smoothing layer and/or a wetting layer.

Claims

1. A material comprising a transparent substrate coated with a stack of thin layers comprising a silver-based functional metal layer and two dielectric coatings, each dielectric coating comprising at least one dielectric layer, so that the functional metal layer is positioned between two dielectric coatings, wherein a lower dielectric coating located below a silver-based functional layer comprises: a high-index layer based on metal oxide, exhibiting a refractive index of greater than 2.3 and a thickness of greater than 5 nm, an antidiffusion layer based on silicon and/or on aluminum chosen from an oxide, a nitride and an oxynitride layer, located above the high-index layer, exhibiting a thickness of between 1 and 10 nm, at least one oxide-based layer located above the antidiffusion layer and exhibiting a different composition from the antidiffusion layer.

2. The material as claimed in claim 1, wherein an upper dielectric coating is located above the silver-based functional layer and comprises at least two thin layers, each with a thickness of greater than 5 nm, the refractive index difference of which is greater than 0.30.

3. The material as claimed in claim 1, wherein the lower dielectric coating additionally comprises a high-index layer exhibiting a thickness of less than 5 nm located above the antidiffusion layer and below the silver-based functional layer.

4. The material as claimed in claim 1, wherein the antidiffusion layer is located above and in contact with the high-index layer exhibiting a thickness of greater than 5 nm.

5. The material as claimed in claim 1, wherein a sum of thicknesses of the oxide-based layers located above the antidiffusion layer in the lower dielectric coating is greater than 5.0 nm.

6. The material as claimed in claim 1, wherein at least one oxide-based layer located above the antidiffusion layer and exhibiting a different composition from the lower dielectric coating is a wetting layer based on zinc oxide.

7. The material as claimed in claim 1, wherein the dielectric coating located below the silver-based functional layer comprises, as oxide-based layers: a smoothing layer based on mixed oxide, located above the antidiffusion layer and exhibiting a different composition, the smoothing layer being either in contact with the antidiffusion layer or separated from the antidiffusion layer by a layer exhibiting a thickness of less than 5 nm, and a wetting layer based on zinc oxide, located above the smoothing layer.

8. The material as claimed in claim 1, wherein the high-index layers based on metal oxide are chosen from titanium oxide or niobium oxide layers or layers of an alloy obtained from titanium and niobium.

9. The material as claimed in claim 1, wherein the antidiffusion layer is chosen from the layers: of silicon oxide, of aluminum oxide and of aluminum silicon oxide, of silicon nitride, of aluminum nitride, of aluminum silicon nitride, of zirconium silicon nitrides, of silicon oxynitrides, of aluminum oxynitrides and of aluminum silicon oxynitrides.

10. The material as claimed in claim 7, wherein the smoothing layer is a layer of mixed oxide comprising one or more metals chosen from tin Sn, zinc Zn, gallium Ga and indium In.

11. The material as claimed in claim 2, wherein the upper dielectric coating comprises at least one high-index layer based on metal oxide exhibiting a refractive index of greater than 2.3 and a thickness of greater than 5 nm.

12. The material as claimed in claim 2, wherein the upper dielectric coating comprises at least one dielectric layer exhibiting a refractive index of less than 2.2 and a thickness of greater than 5 nm located above the high-index layer.

13. The material as claimed in claim 2, wherein the upper dielectric coating comprises at least one layer having a low refractive index exhibiting a refractive index of less than or equal to 1.7 and a thickness of greater than 5 nm.

14. The material as claimed in claim 2, wherein the upper dielectric coating comprises at least the sequence of thin layers deposited in the following order above the functional layer: at least one layer having a high refractive index, made of material with a refractive index of greater than or equal to 2.20, a physical thickness of the layer having a high refractive index or a sum of the physical thicknesses of the layers having a high refractive index being between 10 and 40 nm, at least one layer having a low refractive index, made of material with a refractive index of less than or equal to 1.70, a physical thickness of the layer having a low refractive index or a sum of the physical thicknesses of the layers having a low refractive index being between 40 and 120 nm.

15. The material as claimed in claim 1, wherein the substrate is made of glass or of a polymeric organic substance.

16. A process for obtaining a material comprising a transparent substrate coated with a stack of thin layers as claimed in claim 1, comprising depositing the thin layers by cathode sputtering, optionally magnetic-field-assisted cathode sputtering, wherein a high-temperature heat treatment of the bending, tempering or annealing type is carried out on said substrate.

17. The material as claimed in claim 6, wherein the wetting layer based on zinc oxide is located directly in contact with the silver-based metal layer.

18. The material as claimed in claim 15, wherein the glass is soda lime glass.

Description

EXAMPLES

[0240] Several types of stacks of thin layers defined below are deposited on substrates made of clear soda-lime glass with a thickness of 3.9 mm, in a known way, on a cathode sputtering line (magnetron process) in which the substrate will progress forward under different targets.

[0241] For these examples, the conditions for deposition of the layers deposited by sputtering (magnetron cathode sputtering) are summarized in table 1 below.

TABLE-US-00001 TABLE 1 Deposition Targets employed pressure Gas Index Si.sub.3N.sub.4 Si:Al (92:8% by wt) 2-15 * 10.sup.3 mbar Ar 47% - N.sub.2 53% 2.00 ZrO.sub.2 ZrO.sub.2 8 * 10.sup.3 mbar Ar 90% - O.sub.2 10% 2.1 SiZrAlN Si:Al:Zr (70:8:22 at. %) 2 * 10.sup.3 mbar Ar 55% - N.sub.2 45% 2.22 SnZnO.sub.x Sn:Zn (60:40% by wt) 1.5 * 10.sup.3 mbar Ar 39% - O.sub.2 61% 2.09 ZnO ZnAlO (98:2% by wt) 1.5 * 10.sup.3 mbar Ar 91% - O.sub.2 9% 2.04 Ag Ag 8 * 10.sup.3 mbar 100% Ar NiCr Ni:Cr (80:20 at. %) 2 * 10.sup.3 mbar 100% Ar SiO.sub.2 Si:Al (92:8% by wt) 2-5 * 10.sup.3 mbar Ar 70% - O.sub.2 30% 1.55 TiO.sub.2 TiO.sub.x 1.5 * 10.sup.3 mbar Ar 88% - O.sub.2 12% 2.32 at.: atomic; wt: weight; Index: at 550 nm.

[0242] Table 1 shows, for each material tested, the physical thicknesses of the layers of the stack, expressed in nm (unless otherwise indicated). The first line corresponds to the layer furthest from the substrate, in contact with the open air.

[0243] The materials provided with the stack are subjected to a heat treatment of tempering type which consists in particular in heating at 620 C. for 10 minutes.

I. Evaluation of the Matchable Nature

[0244] The matchable nature according to the invention is characterized by the absence of variation, before and after heat treatment: [0245] in the scattering, which is reflected by the absence of haze or of defects, [0246] in the colors.

[0247] For each material described in tables 2 and 3, observations which make it possible to evaluate the haze, the defects and the colorimetric variations have been listed.

[0248] These evaluations give accounts of variations due to the high-temperature heat treatment.

1. Evaluation of the Scattering by Measurement of the Haze

[0249] The phenomena of scattering of the light are expressed visually by the appearance of a light halo, known as haze, visible generally under intense light.

[0250] The haze was assessed visually by a panel of several people who observe the presence or absence of a white veil or light halo appearing after heat treatment. The panel assigned, for each glazing, an assessment indicator chosen from:

: presence of a pronounced white veil expressing strong scattering,
0: slight white veil expressing weak scattering,
+: absence of white veil expressing the absence of scattering.

[0251] The haze corresponds to the amount of the transmitted light which is scattered at angles of more than 2.5. This haze can also be evaluated by measurement of the mean visible diffuse reflection with the Perkin-Elmer L900 spectrometer. The measurement consists in taking the mean of the scattered part of the reflection over the visible region, the specular reflection being excluded from the measurement and the base line taken on a non-haze reference sample being subtracted. It is expressed as percentage with respect to a total reflection measured on a reference mirror.

2. Evaluation of the Presence of Defects in the Silver Layer

[0252] The analysis by optical microscopy or by scanning electron microscopy makes it possible to demonstrate the presence of defects after heat treatment.

[0253] The following assessments are reported after microscopic observation:

: Presence of numerous defects in the silver layer,
0: Presence of a few defects in the silver layer,
+: Absence of defects,
X: No information available.

[0254] Finally, the type of defect is described in the following way: [0255] D: defect of dome type, [0256] H: defect of hole type, [0257] 0: No defect visible, [0258] X: No information available.

3. Evaluation of Colorimetric Variations

[0259] The colorimetric variations in transmission and in reflection before and after heat treatment were evaluated visually by a panel of several people. The panel assigned, for each glazing, an assessment indicator chosen from:

: variations in color visible to the eye, rendering the material nonmatchable,
0: slight variations in color, not rendering the material nonmatchable,
+: no variation in color visible to the eye, material matchable.

TABLE-US-00002 TABLE 2 Glazing Cp. Cp. 0 Cp. 1 Cp. 2 Cp. 2 Cp. 2 Cp. 2 Cp. 3 Cp. 3 3 Protective layer ZrO.sub.2 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Upper DC Dielectric layer Si.sub.3N.sub.4 37 37 37 37 20 SnZnO 17 Low-index layer SiO.sub.2 62 60 60 62 High-index layer TiO.sub.x 20 20 20 20 Dielectric layer ZnO 7 7 5 5 5 5 5 5 7 Blocking layer NiCr 0.5 0.5 1 1 1 1 1 1 0.5 Functional layer Ag 9.2 9.2 9 9 9 9 9 9 9.2 Lower DC Wetting layer ZnO 6 6 5 5 5 5 6 Smoothing layer SnZnO 23 23 10 10 10 10 18 Intermediate layer TiO.sub.x Antidiffusion layer SiZrN Si.sub.3N.sub.4 High-index layer TiO.sub.x 2 2 10 10 10 10 10 10 10 Dielectric layer Si.sub.3N.sub.4 6 6 5 5 5 5 5 5 6 Substrate (mm) Glass 3.9 3.9 3.9 3.9 3.9 3.9 3.9 3.9 3.9 Observations Colorimetry + + + + + + Scattering + + 0 0 0 0 Visual defects 0 0 0 0 0 X Type of defect D X H D D D H X H

TABLE-US-00003 TABLE 3 Glazing Inv. Inv. 1 1 Inv. 1 Inv. 2 Inv. 2 Inv. 2 Inv. 4 Inv. 4 Inv. 5 Inv. 5 Inv. 6 Inv. 6 Inv. 7 Protective layer Upper DC Dielectric layer Si.sub.3N.sub.4 37 Low-index layer SnZnO 37 37 SiO.sub.2 60 60 60 60 60 60 60 60 High-index layer TiO.sub.x 20 20 20 20 20 20 20 20 20 20 20 Dielectric layer ZnO 5 5 5 5 5 5 5 5 5 5 5 5 5 Blocking layer NiCr 1 1 1 1 1 1 1 1 1 1 1 1 1 Functional layer Ag 9 9 9 9 9 9 9 9 9 9 9 9 9 Lower DC Wetting layer ZnO 5 5 5 5 5 5 5 5 5 5 5 Smoothing layer SnZnO 10 10 10 10 10 10 10 10 10 10 10 Intermediate layer TiO.sub.x 2-3 2-3 2-3 2-3 2-3 2-3 2-3 Antidiffusion layer SiZrN 3 3 3 Si.sub.3N.sub.4 3 3 3 3 3 3 3 3 3 3 High-index layer TiO.sub.x 10 10 10 10 10 10 10 10 10 10 10 10 10 Dielectric layer Si.sub.3N.sub.4 5 5 5 5 5 5 5 5 5 5 5 5 5 Substrate (mm) Glass 3.8 3.8 3.8 3.8 3.8 3.8 3.8 3.8 3.8 3.8 3.8 3.8 3.8 Observations Colorimetry + + + + + + + + + + + + + Scattering 0 0 0 + + + 0 + 0 + 0 + + Visual defects 0 0 0 + + + 0 0 0 0 0 + + Type of defect D X D X X 0 X X X X X X X

[0260] These examples show that scattering visible to the eye is not observed: [0261] in the absence of a high-index layer or of a sequence of high- and low-index layers in the upper dielectric coating and in the absence of a high-index layer with a thickness of greater than 5 nm in the lower dielectric coating (Cp. 0), [0262] in the presence of a sequence of high- and low-index layers in the upper dielectric coating, without a high-index layer with a thickness of greater than 5 nm in the lower dielectric coating (Cp. 1).

[0263] For this, a basis may be taken on Cp. 0 and Cp. 1 in comparison with Cp. 3.

[0264] Significant variations in optical and colorimetric properties are observed that when: [0265] the lower dielectric coating comprises a high-index layer of more than 10 nm and [0266] the upper dielectric coating with a nonhomogeneous refractive index comprises layers with different refractive indices.

[0267] The dielectric coatings with nonhomogeneous refractive indices can be respectively composed of a sequence of layers with different indices, preferably based on oxide, such as: [0268] of a high-index TiO.sub.2 layer and of a low-index SiO.sub.2 layer, [0269] of a high-index layer and of a SnZnO.sub.x layer, [0270] of a ZnO layer and of a SiO.sub.2 layer, [0271] of a ZnO layer and of a TiO.sub.2 layer.

[0272] For this, it is possible to compare: [0273] example Cp. 2 (little scattering and no variation in color) with example Cp. 3 (scattering and variation in color), [0274] example Cp. 2 (little scattering and no variation in color) with example Cp. 3 (scattering and variation in color), [0275] example Cp. 2 (little scattering and no variation in color) with example Cp. 3 (scattering and variation in color).

[0276] The solution of the invention, which consists in adding an antidiffusion layer, for example based on silicon and/or aluminum nitride, located above the high-index layer and below the oxide layer, makes it possible to reduce the haze (improvement in the scattering from to 0) and the colorimetric variations subsequent to a high-temperature heat treatment (improvement in the colorimetry from to +). A few defects in the silver layer remain observable.

[0277] The even more advantageous solution, which consists in adding both an antidiffusion layer and a high-index intermediate layer exhibiting a thickness of less than 5 nm, located above the antidiffusion layer and below the silver-based functional layer, makes it possible to improve, in addition, the quality of the silver layer (improvement in the scattering from to + and decrease in the defects).

[0278] For this, it is possible to compare: [0279] example Cp. 3 with examples Inv. 1 and Inv. 2, [0280] example Cp. 3 with examples Inv. 1 and Inv. 2, [0281] example Cp. 3 with examples Inv. 1 and Inv. 2.

[0282] Some examples are combined in table 4 in order to make the advantages of the invention easier to understand.

TABLE-US-00004 TABLE 4 Glazing Cp. 3 Inv. 1 Inv. 2 Cp. 3 Inv. 1 Inv. 2 Cp. 3 Inv. 1 Inv. 2 Protective layer ZrO.sub.2 2.5 2.5 2.5 Upper DC Dielectric layer Si.sub.3N.sub.4 SnZnO Low-index layer SiO.sub.2 60 60 60 60 60 60 62 60 60 High-index layer TiO.sub.x 20 20 20 20 20 20 20 20 20 Dielectric layer ZnO 5 5 5 5 5 5 7 5 5 Blocking layer NiCr 1 1 1 1 1 1 0.5 1 1 Functional layer Ag 9 9 9 9 9 9 9.2 9 9 Lower DC Wetting layer ZnO 5 5 5 6 5 5 Smoothing layer SnZnO 10 10 10 18 10 10 Intermediate layer TiO.sub.x 2-3 2-3 2-3 Antidiffusion layer SiZrN 3 3 3 Si.sub.3N.sub.4 3 3 3 High-index layer TiO.sub.x 10 10 10 10 10 10 10 10 10 Dielectric layer Si.sub.3N.sub.4 5 5 5 5 5 5 6 5 5 Substrate (mm) Glass 3.9 3.8 3.8 3.9 3.8 3.8 3.9 3.8 3.8 Observations Colorimetry + + + + + + Scattering 0 + 0 + 0 + Visual defects 0 + X 0 + 0 + Type of defect H D X X X X H D 0

II. Study of the Interdiffusion Phenomenon

[0283] The profiles of the element titanium in the comparative material Cp. 3 and in the material according to the invention Inv. 1 were determined in order to show the phenomenon of interdiffusion between the high-index layer and the oxide layer, such as the smoothing layer. The graphs illustrating these concentration profiles are obtained by SIMS (Secondary Ion Mass Spectrometry) and represent, on the abscissa, a measurement of depth D corresponding to the ion stripping and, on the ordinate, the concentration corresponding to the element titanium analyzed, in arbitrary units.

[0284] FIG. 1 represents, for the comparative material Cp. 3, the profile of the element titanium before (curve with continuous line) and after (curve with dotted line) heat treatment of tempering type. The migration of the titanium from the high-index layer toward the smoothing layer, corresponding to an offsetting toward the left of the curve obtained after heat treatment with respect to the curve obtained before heat treatment, is clearly observed.

[0285] FIG. 2 represents, for a material according to the invention Inv. 1, the profile of the element titanium before (curve with continuous line) and after (curve with dotted line) heat treatment of tempering type. Clear migration of the titanium into the smoothing layer is not observed. The two curves are not significantly offset. The antidiffusion layer based on zirconium silicon nitride clearly prevents the migration of titanium from the high-index layer toward the smoothing layer.

III. Optical Performance Levels

[0286] The following characteristics were measured and combined in the table below: [0287] LT indicates the light transmission in the visible region in %, measured according to the illuminant D65 at 2 Observer, [0288] ET corresponds to the energy transmission, [0289] ER corresponds to the energy reflection, [0290] g corresponds to the solar factor, [0291] L*T, a*T and b*T indicate the colors in transmission L*, a* and b* in the L*a*b* system, measured according to the illuminant D65 at 2, observer on the side of the stack and measured thus perpendicularly to the glazing, [0292] LR indicates the light reflection in the visible region in %, measured according to the illuminant D65 at 2 Observer on the side of the stack or on the side of the substrate corresponding to the side opposite that of the stack, [0293] L*R, a*R and b*R indicate the colors in reflection L*, a* and b* in the L*a*b* system, measured according to the illuminant D65 at 2, observer on the side of the stack or on the side of the substrate and measured thus perpendicularly to the glazing, [0294] E represents the variation between the values L*, a* and b* which are obtained for a coated substrate, before and after having been subjected to a heat treatment. The variation is calculated in the following way: E=(a*.sup.2+b*.sup.2+L*2).sup.1/2.

[0295] These characteristics are measured for a material provided with the stack first at the outlet of the magnetron line and then after heat treatment of tempering type.

TABLE-US-00005 Transmission LT ET L*T a*L b*L EL g Cp. 0 BT 86.8 68.1 94.6 1.2 1.1 0.5 0.70 AT 88.2 68.9 94.8 0.6 1.9 0.70 Cp. 0 BT 88 69.7 95.2 1.5 2.1 1.2 AT 90.3 71.6 96.1 0.9 1.6 Cp. 3 BT 85.4 69.2 94.1 1.8 2.6 1.0 AT 85.8 70.2 94.2 1.1 0.7 Cp. 3 BT 84 93.4 1.3 1.1 2.2 AT 85.6 94.1 0.8 0.9 Inv. 1 BT 82.6 92.8 1.4 1.4 1.0 AT 83.7 93.3 1.8 2.2 Inv. 2 BT 86.8 68.1 94.7 2.6 3.7 1.2 0.705 AT 89.4 69.3 95.8 3 4.1 0.698 BT: Before heat treatment, AT: After heat treatment.

TABLE-US-00006 Reflection stack side Reflection glass side LR ER LR a*R b*R ER LR ER LR a*R b*R ER Cp. 0 BT 4.8 19.2 26.2 0.9 9.2 2.1 6.6 16.5 30.8 1.0 7.3 2.1 AT 5.5 19.8 29.3 2.6 10.1 7.7 17.2 33.3 3.6 8.1 Cp. 0 BT 5.1 18.6 27.1 0.6 8.2 2.1 6.4 16.4 30.5 0.1 8.6 1.4 AT 5.4 20.1 27.7 1.4 8.5 6.2 17.6 29.9 1.4 8.5 Cp. BT 6.5 16.4 30.7 2.7 11.1 6.4 8.3 15.9 34.5 2.5 4.3 4.9 3 AT 7.7 17 32.7 0.3 0.4 9.3 16.2 36.5 0.5 4.1 Cp. BT 8.7 35.4 1 3.6 8.5 10.2 38.2 1.1 1.1 4.8 3 AT 10.1 37.9 0.4 4.4 10.9 39.5 0.3 5.5 Inv. BT 8.7 35.4 0.8 4.6 2.6 10.1 37.9 1.0 0.7 0.8 1 AT 10.1 38 1 4.4 10.4 38.5 0.4 0.7 Inv. BT 4.4 18.6 24.9 8.2 16.8 0.9 5.5 15.3 28.1 5.9 15.2 2.6 2 AT 4.6 19.7 25.6 8.6 16.4 5.2 16 27.4 5.9 12.7

[0296] These examples show that: [0297] few colorimetric variations are not observed in the absence of a sequence of high- and low-index layers in the upper dielectric coating and in the absence of a high-index layer with a thickness of greater than 5 nm in the lower dielectric coating (Cp. 0), [0298] significant variations are not observed in the presence of a sequence of high- and low-index layers in the upper dielectric coating and in the presence of a high-index layer with a thickness of greater than 5 nm in the lower dielectric coating (Cp. 3).

[0299] These colorimetric variations are greatly reduced by virtue of the antidiffusion layer based on silicon nitride, in particular a E in reflection: [0300] stack side, which decreases from more than 6 (Cp. 3) to 2.6 (Inv. 1) or 0.9 (Inv. 2), [0301] glass side, which decreases from approximately 5 (Cp. 3) to 0.8 (Inv. 1) or 2.6 (Inv. 2).

[0302] The example according to the invention 1 exhibits a high light transmission and slight colorimetric variations.

[0303] The example according to the invention 2, comprising both the antidiffusion layer and the intermediate layer, exhibits an even higher light transmission, slight colorimetric variations and a very high solar factor.