SOLAR-CONTROL GLAZING

Abstract

The present invention relates to solar-control glazings intended to be fitted in buildings, but also in motor vehicles. They comprise a glass substrate carrying a transparent multilayer stack comprising an alternation of n silver-based functional layers that reflect infrared radiation and of n+1 dielectric coatings, with n1, such that each functional layer is surrounded by dielectric coating. At least one of the dielectric coatings comprises a substantially metallic solar radiation absorbing layer based on Pd, enclosed between and in contact with two dielectric oxide layers of at least one element selected from Zn, Sn, Al, In, Nb, Ti and Zr.

Claims

1. A transparent solar-control glazing comprising a glass substrate and a transparent multilayer stack on at least one face of the glass substrate, the transparent multilayer stack comprising an alternation of n silver-based functional layers that reflect infrared radiation and of n+1 dielectric coatings, with n1, such that each functional layer is surrounded by dielectric coatings, wherein at least one of the dielectric coatings comprises a substantially metallic solar radiation absorbing layer based on Pd, enclosed between and in contact with two dielectric oxide layers of at least one element selected from the group consisting of Zn, Sn, Al, In, Nb, Ti and Zr, said dielectric oxide layers having a thickness of at least 8 nm.

2. The transparent solar-control glazing of claim 1, wherein the solar radiation absorbing layer consists essentially of palladium.

3. The transparent solar-control glazing of claim 1, wherein the solar radiation absorbing layer has a thickness between 0.3 and 10 nm.

4. The transparent solar-control glazing of claim 1, wherein the dielectric oxide layers surrounding and contacting the solar radiation absorbing layer are deposited from a ceramic target.

5. The transparent solar-control glazing of claim 1, wherein the dielectric oxide layers surrounding and contacting the solar radiation absorbing layer have a thickness between 8 and 80 nm.

6. The transparent solar-control glazing of claim 1, wherein the multilayer stack comprises at least two silver-based functional layers that reflect infrared radiation.

7. The transparent solar-control glazing of claim 1, wherein the solar radiation absorbing layer is placed between two silver-based functional layers that reflect infrared radiation.

8. The transparent solar-control glazing of claim 1, further comprising a barrier layer above and in contact with a silver-based functional layer, said barrier layer being a metallic sacrificial layer or an oxide layer deposited from a ceramic target.

9. The transparent solar-control glazing of claim 1, further comprising a wetting layer under and in contact with a silver-based functional layer.

10. The transparent solar-control glazing of claim 1, having a light transmission LT between 20% and 70%.

11. A laminated glazing, comprising the transparent solar-control glazing of claim 1.

12. An insulating multiple glazing, comprising the transparent solar-control glazing of claim 1.

13. The insulating multiple glazing of claim 12, wherein a solar factor SF, measured according to standard EN410, is between 12% and 40% for a 6/15/4 double glazing made of clear glass.

14. The insulating multiple glazing of claim 13, wherein a selectivity, expressed in the form of the light transmission LT relative to the solar factor SF, is at least 1.4.

Description

5. DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0062] The invention will now be described in more detail in a non-restrictive manner by means of the following preferred exemplary embodiments. Examples of multilayer stacks deposited on a glass substrate to form glazings according to the invention, but also comparative examples (C), are given in tables 1 to 3 below. The layers are in order, from left to right, starting from the glass.

[0063] The various layers are applied via a cathodic sputtering technique under usual conditions for this type of technique. The metallic layers are deposited in an inert atmosphere of argon. The oxide layers denoted ceram are deposited, from a ceramic target under an inert atmosphere of argon. The other oxides are deposited from a metallic target under a reactive atmosphere of oxygen and argon.

[0064] Comparative example 1 shows a coating stack of the prior art type wherein the solar radiation absorbing layer is metallic and arranged in the immediate vicinity of the functional layer. This comparative example shows that palladium is a good candidate as temperable absorber because it maintains its absorption properties after heat treatment (ratio ABS well above 0.5). However in this particular case the sheet resistance after heat treatment, and so the emissivity, is greatly increased (ratio R/=2.0), which unacceptably degrades the energetic performance of the glazing. This is due to the diffusion of palladium into the silver layer, degrading its quality. Note that emissivity values may be calculated from sheet resistance measurements for coating stacks including a single silver layer, with the following formula: E=R/*1.1/100.

[0065] Comparative examples 2 to 8 disclose various other materials for the absorbing layer. All these comparative examples show a huge loss of their absorption properties after heat treatment (ratio ABS below 0.5). Comparative example 7, in addition, shows a very much degraded sheet resistance.

[0066] On the other hand examples 1 to 5, shows that palladium maintains its absorption properties after heat treatment and that the sheet resistance may at least be maintained or even improved, when palladium is not in close proximity with the silver layer, but surrounded by oxide layers. In addition, when comparing example 2 to example 1 and example 4 to example 3, it can be seen that using oxide layers deposited from ceramic targets as oxide layers surrounding palladium further decrease the sheet resistance after heat treatment.

[0067] The coating stacks described in table 2 are an attempt to provide a range of solar control glazings with luminous transmissions in double-glazing of around 40, 50 and 60%, using palladium between oxide layers. These double-glazings include a first pane made of a 6 mm thick mid-iron glass coated with the defined coating stack which has been heat-treated, a second pane made of a 4 mm thick clear glass, and a 15 mm thick spacing between the two panes filled with 90% argon. Light transmission, solar factor and selectivity values are given.

[0068] Small samples of these coating stacks deposited on a 4 mm-thick glass where heat treated in a static lab furnace at 670 C. during increasing durations from 6 to 9 minutes, while 6 minutes is considered as standard duration for a 4 mm-thick glass sheet. Table 2 shows the haze level from 0 (perfect) to 5 (bad). Whilst a haze level of less than 3 is acceptable, a haze level of 3 or 3,5 is borderline and a haze level of 4 or more is unacceptable. These results show that the haze level of stacks including the succession oxide/Pd/oxide are generally low even with longer heat treatments, showing their thermal stability.

[0069] The overall chemical and mechanical durability of these coating stacks is good, i.e. similar to other known solar-control stacks of this type.

[0070] Table 3 shows the advantages of using oxide layers deposited from ceramic targets as oxide layers surrounding palladium. These double-glazings include a first pane made of a 6 mm thick mid-iron glass coated with the defined coating stack which has been heat-treated, a second pane made of a 4 mm thick mid-iron glass, and a 15 mm thick spacing between the two panes filled with 90% argon. Light transmission, solar factor, selectivity and haze values are given.

[0071] When comparing example 10 with example 9, it can be seen that using oxide layers deposited from ceramic targets as oxide layers surrounding palladium provides better selectivity and decreased emissivity. When comparing example 11 with example 12, it can be seen that using oxide layers deposited from ceramic targets as oxide layers surrounding palladium provides a better haze value.

[0072] As already said, the present invention has the additional advantage that multilayer solar-control stacks can be deposited in a single atmosphere, using ceramic oxide targets. The following examples of coating stacks can be deposited in a full argon atmosphere (same nomenclature as for Tables 1-3).

TABLE-US-00001 ZSO5 ceram Pd ZSO5 ceram ZnO ceram Ag AZO ZSO5 ceram TiO.sub.2 ceram ZSO5 ZnO Ag AZO ZSO5 Pd ZSO ZnO Ag AZO ZSO5 TZO ceram ceram ceram ceram ceram ceram ZSO5 AZO Ag Ti ZSO5 Pd ZSO AZO Ag Ti ZSO5 Ti C ceram ceram ceram ceram

TABLE-US-00002 TABLE 1 ABS ABS ratio R/ ratio BB AB ABS BB R/nAB R/ C1 ZSO5 ZnO Ag Pd Ti ZSO5 TiO.sub.2 300 100 110 20 50 300 50 34.7 32.4 0.9 4.0 8.0 2.0 C2 ZSO5 Cr ZSO5 ZnO Ag Ti ZSO5 TiO.sub.2 ceram ceram ceram ceram 150 20 150 100 110 50 300 50 50.1 5.9 0.1 5.3 3.2 0.6 C3 ZSO5 NiCr ZSO5 ZnO Ag AZO ZSO5 SiN 200 13.7 mg/m.sup.2 150 50 100 50 150 150 12.4 5.53 0.4 5.2 3.4 0.6 C4 ZSO5 NiCr ZSO5 ZnO Ag AZO ZSO5 SiN ceram ceram 200 10.8 mg/m.sup.2 150 50 100 50 150 150 14.8 5.6 0.4 4.1 2.8 0.7 C5 ZSO5 NiCrW ZSO5 ZnO Ag AZO ZSO5 SiN ceram ceram 200 15 150 50 100 50 150 150 15.2 5.86 0.4 4.0 2.7 0.7 C6 ZSO5 ZnO Ag Ti ZSO5 NiV ZSO5 TiO.sub.2 ceram ceram 205 50 100 50 150 18.5 mg/m.sup.2 150 50 39.6 5.8 0.1 6.4 6.4 1.0 C7 ZSO5 ZnO Ag Ti ZSO5 Cu ZSO5 TiO.sub.2 205 50 100 50 150 75 mg/m.sup.2 150 50 80.8 20.7 0.3 4.5 32.7 7.2 C8 ZSO5 ZnO Ag Ti ZSO5 NiVCu ZSO5 TiO.sub.2 205 50 100 50 150 NiV: 18.5 mg/m.sup.2 150 50 35.8 7.8 0.2 7.3 6.4 0.9 1 ZSO5 ZnO Ag Ti ZSO5 Pd ZSO5 TiO.sub.2 205 50 100 50 150 25 150 50 36.3 27.7 0.8 5.5 5.1 0.9 2 ZSO5 ZnO Ag Ti ZSO5 Pd ZSO5 TiO.sub.2 ceram ceram 205 50 100 50 150 25 150 50 39.6 25.8 0.7 6.4 4.5 0.7 3 ZSO5 Pd ZSO5 ZnO Ag AZO ZSO5 SiN 200 30 150 50 100 50 150 150 30.0 30.4 1.0 5.1 3.4 0.7 4 ZSO5 Pd ZSO5 ZnO Ag AZO ZSO5 SiN ceram ceram 200 30 150 50 100 50 150 150 30.6 30.4 1.0 4.4 2.6 0.6 5 ZSO5 Pd ZSO5 ZnO Ag Ti ZSO5 TiO.sub.2 ceram ceram 150 20 150 100 110 50 300 50 45.5 30.6 0.7 4.5 2.8 0.6

TABLE-US-00003 TABLE 2 ZSO5 ZSO5 ZSO5 ZnO Ag Ti ZSO5 ceram Pd ceram ZSO5 ZnO Ag Ti 6 205 50 127 50 36 150 10.1 150 400 50 146 50 7 230 50 134 50 305 150 19.2 150 156 50 174 50 8 230 50 151 50 322 150 25.9 150 165 50 187 50 haze after 6 7 8 ZSO5 TiN C LT SF S min min min 6 327 ~35 ~60 62.0 35.2 1.76 2 3 3 7 323 ~35 ~60 49.0 27.5 1.78 2 2.5 2 8 333 ~35 ~60 40.1 22.4 1.79 2 3 3.5

TABLE-US-00004 TABLE 3 ZSO5 ZSO5 ZSO5 ZnO Ag Ti ZSO5 ceram Pd ceram ZSO5 ZnO Ag Ti ZSO5 TiN C LT SF S E haze 9 230 50 154 55 425 25.9 360 50 190 55 307 ~35 ~60 36.8 21.4 1.72 0.017 10 230 50 151 50 250 150 25.9 150 165 50 187 50 315 ~35 ~60 38.0 21.3 1.79 0.011 11 230 50 151 55 405 25.9 335 50 187 55 310 ~35 ~60 4 12 230 50 151 50 322 150 25.9 150 165 50 187 50 333 ~35 ~60 2

TABLE-US-00005 Tables legend ABS BB luminous absorption before bake, i.e. before heat-treatment, expressed in % ABS AB luminous absorption after bake, i.e. after heat-treatment, expressed in % ratio ABS =ABS AB/ABS BB R/ BB sheet resistance before bake, i.e. before heat-treatment, expressed in / R/ AB sheet resistance after bake, i.e. after heat-treatment, expressed in / ratio R/ =R/ AB/R/ BB LT light transmission SF solar factor, expressed in % S selectivity, expressed in % ZSO5 Mixed zinc-tin oxide (zinc stannate Zn.sub.2SnO.sub.4) formed from a cathode of a zinc-tin alloy containing 52 Wt % zinc and 48 Wt % tin, under an oxidising atmosphere ZSO5 ceram Mixed zinc-tin oxide (zinc stannate Zn.sub.2SnO.sub.4) formed from a ceramic cathode of a 52/48 zinc-tin oxide, under an inert atmosphere of argon ZnO Oxide of zinc deposited from a metallic target of zinc under an oxidising atmosphere ZnO ceram Oxide of zinc deposited from a ceramic target of zinc oxide in an inert atmosphere of argon NiCr Alloy of 80/20 nickel/chromium NiCrW Alloy of 80/20 nickel/chromium (50 Wt %) and of W (50 Wt %) AZO Mixed oxide of zinc and aluminium, deposited from a ceramic target of zinc oxide doped with 2 Wt % aluminium, under an inert atmosphere of argon SiN Silicon nitride without representing a chemical formula, it being understood that the products obtained are not necessarily rigorously stoichiometric. The SiN layers may contain up to a maximum of about 10% by weight of aluminium originating from the target. NiV Alloy resulting of the sputtering of a 93/7 nickel/vanadium target in an argon atmosphere NiVCu Alloy resulting of the co-sputtering of a 93/7 nickel/vanadium target and of a copper target in an argon atmosphere, to get into the layer a proportion of 90 Wt % NiV and 10 Wt % Cu TZO Mixed oxide comprising 50% TiO.sub.2 and 50% ZrO.sub.2 absorbing materials in the stacks are in bold poor results are in bold and underlined except specified otherwise, all thicknesses are expressed in * value expressed in inch/minute, when power = 0.2 kW, pressure = 3.7 mTorr, under 100% Ar