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 at least one element selected from the group consisting of Co, Ru, Rh, Re, Os, Ir, Pt, enclosed between and in contact with two dielectric oxide layers.

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 comprising at least one element selected from the group consisting of Co, Ru, Rh, Re, Os, Ir, Pt, enclosed between and in contact with two dielectric oxide layers, 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 comprises ruthenium.

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

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

5. The transparent solar-control glazing of claim 1, wherein the dielectric oxide layers surrounding and contacting the solar radiation absorbing layer are layers of an oxide of at least one element selected from the group consisting of Zn, Sn, Si, Al, In, Nb, Ti and Zr.

6. 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.

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

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

9. 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.

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

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

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

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

14. The insulating multiple glazing of claim 13, 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.

15. The insulating multiple glazing of claim 14, 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 example 2 again shows that palladium maintains its absorption properties after heat treatment and in addition shows that the sheet resistance may at least be maintained or even improved when palladium is not in close proximity with the silver layer.

[0066] Comparative examples 3 to 9 and example 1 compare various other materials for the absorbing layer. All the comparative examples 3 to 9 show a huge loss of their absorption properties after heat treatment (ratio ABS below 0.5). Comparative example 8, in addition, shows a very much degraded sheet resistance. On the other hand example 1, with ruthenium, maintains enough absorption and offers a well-decreased sheet resistance after heat treatment.

[0067] In view of table 1 results, palladium and ruthenium both seem good candidates as material for a heat-treatable absorbing layer. However we have found that palladium enclosed between and in contact with two oxide layers may show lower selectivity and higher haze after heat treatment than ruthenium, and some durability issues (see Tables 2 and 3 hereunder).

[0068] 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 and ruthenium. 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. It has to be noted that the coating stack of example 4 was not fully tuned and therefore shows a worse selectivity, which can be solved by decreasing the thickness of the second dielectric coating. Except for example 4 which was not fully tuned, the ruthenium-based stacks show a better selectivity than the palladium-based stacks.

[0069] 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 the ruthenium-based stacks is particularly low even with longer heat treatments, showing their remarkable thermal stability.

[0070] The overall chemical and mechanical durability of these coating stacks is good, i.e. similar to other known solar-control stacks of this type, except for the palladium-based stacks which show a weakness at the AWRT test (see Table 3). The Automatic Wet Rub Test (AWRT) is a test used to evaluate the resistance of the coating to erosion. A piston covered with a cotton cloth (reference: CODE 40700004 supplied by ADSOL) is brought into contact with the layer to be evaluated and moved back and forth over its surface. The piston carries a weight in order to have a force of 33N acting on a 17 mm diameter finger. The cotton must be kept wet with deionized water throughout the test. The rubbing of the cotton over the coated surface damages (removes) the coating after a certain number of cycles. The test is realised for 250 cycles. The sample is observed under an artificial sky to determine whether discolouring and/or scratching is visible on the sample. The AWRT score is given on a scale from 1 to 10, 10 being the best score, indicating a highly resistant coating.

[0071] 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 Ru ZSO5 ceram ZnO ceram Ag AZO ZSO5 ceram TiO.sub.2 ceram ZSO5 ZnO Ag AZO ZSO5 Ru ZSO ZnO Ag AZO ZSO5 TZO ceram ceram ceram ceram ceram ceram ZSO5 AZO Ag Ti ZSO5 Ru ZSO AZO Ag Ti ZSO5 Ti C ceram ceram ceram ceram

TABLE-US-00002 TABLE 1 ABS ABS ratio R/ R/ ratio BB AB ABS BB AB 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 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 C3 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 C4 ZSO5 NiCr ZSO5 ZnO Ag AZO ZSO5 SiN 200 13.7 150 50 100 50 150 150 12.4 5.53 0.4 5.2 3.4 0.6 mg/m.sup.2 C5 ZSO5 NiCr ZSO5 ZnO Ag AZO ZSO5 SiN ceram ceram 200 10.8 150 50 100 50 150 150 14.8 5.6 0.4 4.1 2.8 0.7 mg/m.sup.2 C6 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 C7 ZSO5 ZnO Ag Ti ZSO5 NiV ZSO5 TiO.sub.2 ceram ceram 205 50 100 50 150 18.5 150 50 39.6 5.8 0.1 6.4 6.4 1.0 mg/m.sup.2 C8 ZSO5 ZnO Ag Ti ZSO5 Cu ZSO5 TiO.sub.2 205 50 100 50 150 75 150 50 80.8 20.7 0.3 4.5 32.7 7.2 mg/m.sup.2 C9 ZSO5 ZnO Ag Ti ZSO5 NiVCu ZSO5 TiO.sub.2 205 50 100 50 150 NiV:18.5 150 50 35.8 7.8 0.2 7.3 6.4 0.9 mg/m.sup.2 Cu:2 mg/m.sup.2 1 ZSO5 ZnO Ag Ti ZSO5 Ru ZSO5 TiO.sub.2 205 50 100 50 150 90 150 50 39.8 23.06 0.6 5.1 3.5 0.7

TABLE-US-00003 TABLE 2 ZSO5 ZSO5 ZSO5 ZnO Ag Ti ZSO5 ceram Pd ceram ZSO5 ZnO Ag C10 205 50 127 50 36 150 10.1 150 400 50 146 C11 230 50 134 50 305 150 19.2 150 156 50 174 C12 230 50 151 50 322 150 25.9 150 165 50 187 haze after 6 7 8 9 Ti ZSO5 TiN C LT SF S min min min min C10 50 327 ~35 ~60 62.0 35.2 1.76 2 3 3 4 C11 50 323 ~35 ~60 49.0 27.5 1.78 2 2.5 2 3 C12 50 333 ~35 ~60 40.1 22.4 1.79 2 3 3.5 4 ZSO5 ZSO5 ZSO5 ZnO Ag Ti ZSO5 ceram Ru ceram ZSO5 ZnO 2 230 50 134 50 315 150 180* 150 140 50 3 230 50 134 50 315 150 130* 150 140 50 4 230 50 134 50 385 150 90* 150 190 50 Ag Ti ZSO5 TiN C 2 155 50 315 ~35 ~60 61.7 33.7 1.83 2 2 2 3 3 174 50 315 ~35 ~60 53.0 28.4 1.87 2 2 2 3 4 174 50 349 ~35 ~60 41.5 24.0 1.73 2 2 2 3

TABLE-US-00004 TABLE 3 ZSO5 ZSO5 ZSO5 ZnO Ag Ti ZSO5 ceram Pd ceram ZSO5 ZnO Ag Ti ZSO5 TiN C AWRT C13 230 50 156 50 337 150 27.3 150 160 50 170 50 366 ~35 ~60 2 ZSO5 ZSO5 ZSO5 ZnO Ag Ti ZSO5 ceram Ru ceram ZSO5 ZnO Ag Ti ZSO5 TiN C 5 230 50 134 50 355 150 90* 150 160 50 174 50 315 ~35 ~60 9

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, expressed in % SF solar factor, expressed in % S selectivity 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 Mixed zinc-tin oxide (zinc stannate Zn.sub.2SnO.sub.4) ceram formed from a ceramic cathode o{square root over (f)} 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 Oxide of zinc deposited from a ceramic target of zinc oxide in an inert ceram 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 NiV-Cu 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, deposited from a ceramic target, under an inert atmosphere of argon 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