Substrate having a multilayer with thermal properties and an absorbing layer

Abstract

The invention relates to a substrate (10) coated on one face (11) with a multilayer of thin films (14) with reflective properties in the infrared and/or in the solar radiation band comprising a single functional metal layer (140), in particular of silver or of a metal alloy containing silver, and two dielectric coatings (120, 160), said coatings each comprising at least one dielectric layer (122, 164), said functional layer (140) being disposed between the two dielectric coatings (120, 160), said multilayer furthermore comprising a single absorbing layer (19), characterized in that said absorbing layer (19) is a metal layer having a physical thickness in the range between 0.5 nm and 1.5 nm, or even between 0.6 nm and 1.2 nm and is situated directly on said face (11) and directly under a dielectric layer of nitride not comprising any oxygen.

Claims

1. A coated substrate consisting of a substrate coated on one face with a multilayer, said multilayer comprising, in the following order from the face of the substrate: an absorbing layer, which is a metal layer having a physical thickness in the range between 0.5 nm and 1.5 nm and which is situated directly on said face; a first dielectric coating comprising at least one dielectric layer, wherein the first dielectric layer comprises a dielectric layer of a nitride not comprising any oxygen that is in direct contact with the absorbing layer; optionally a barrier undercoating comprising nickel or titanium and having a physical thickness e such that 0.2 nm?e?2.5 nm; a single functional metal layer having reflective properties in an infrared and/or in a solar radiation band; optionally a barrier overcoating comprising nickel or titanium and having a physical thickness e such that 0.2 nm?e?2.5 nm; and a second dielectric coating comprising at least one dielectric layer, wherein: the multilayer comprises no more than one absorbing layer excluding the optional barrier overcoating and the optional barrier undercoating; if the barrier undercoating is present, the functional layer is deposited directly onto the barrier undercoating; and if the barrier overcoating is present, the functional layer is deposited directly under the barrier undercoating.

2. The substrate of claim 1, wherein the metal absorbing layer is a layer of titanium.

3. The substrate of claim 1, wherein the first dielectric coating comprises a high index layer of a material having a refractive index in the range between 2.3 and 2.7.

4. The substrate of claim 3, wherein the high index layer has a physical thickness in the range between 5 and 15 nm.

5. The substrate of claim 1, wherein a physical thickness of the dielectric layer of nitride is in the range between 10 and 20 nm.

6. The substrate of claim 1, wherein the barrier undercoating is present and/or the barrier overcoating is present.

7. The substrate of claim 1, wherein a final layer of an overlying dielectric coating layer furthest from the substrate is an oxide based on titanium oxide (TiO.sub.x) or a mixed oxide of zinc and tin (SnZnO.sub.x).

8. A multiple glazing unit, comprising at least two substrates which are held together by a chassis structure, said glazing unit forming a separation between an external space and an internal space, wherein: at least one gas separation layer is disposed between the two substrates; and at least one of the two substrates is a substrate of claim 1.

9. The multiple glazing unit of claim 8, wherein the glazing unit exhibits a selectivity S, which corresponds to a ratio of a light transmission T.sub.L in visible over a solar factor FS, >1.45 while at the same time having a light transmission T.sub.L>55%, or wherein the glazing unit exhibits a selectivity S?1.5 while at the same time having a light transmission T.sub.L?57%.

10. The substrate of claim 1, wherein the single functional metal layer is a metal layer comprising silver or a metal alloy containing silver.

11. The substrate of claim 1, wherein the metal layer has a physical thickness in the range between 0.6 nm and 1.2 nm.

12. The substrate of claim 3, wherein the high index layer comprises an oxide.

13. The substrate of claim 5, wherein the dielectric layer of nitride comprises silicon nitride Si.sub.3N.sub.4.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The details and advantageous features of the invention will become apparent from the following non-limiting examples, illustrated with the aid of the appended figures illustrating:

(2) in FIG. 1, a functional monolayer stack of the prior art, the functional layer having a barrier undercoating and a barrier overcoating;

(3) in FIG. 2, a functional monolayer stack according to the invention, the functional layer being deposited directly onto a barrier undercoating and directly under a barrier overcoating; and

(4) in FIG. 3, a double glazing solution incorporating a functional monolayer stack.

(5) In these figures, the proportions between the thicknesses of the various layers or of the various elements are not rigorously adhered to in order to facilitate their reading.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 illustrates a structure of a functional monolayer stack of the prior art deposited onto a glass substrate 10, being transparent, in which the single functional layer 140, in particular based on silver or of a metal alloy containing silver, is disposed between two dielectric coatings, the underlying dielectric coating 120 being situated underneath the functional layer 140 in the direction of the substrate 10 and the overlying dielectric coating 160 being disposed on top of the functional layer 140 in the opposite direction to the substrate 10.

(7) These two dielectric coatings 120, 160 each comprise at least two dielectric layers 122, 124, 126, 128; 162, 164, 166.

(8) Potentially, on the one hand, the functional layer 140 may be deposited directly onto a barrier undercoating 130 disposed between the underlying dielectric coating 120 and the functional layer 140 and, on the other hand, the functional layer 140 may be deposited directly under a barrier overcoating 150 disposed between the functional layer 140 and the overlying dielectric coating 160.

(9) The barrier under- and/or overlayers, although deposited in the form of a metal and presented as being metallic layers, are in practice oxidized layers since their primary function is to become oxidized during the deposition of the multilayer in order to protect the functional layer.

(10) This dielectric coating 160 may be finished off by an optional protection layer 168, in particular a layer based on oxide, notably under-stoichiometric in oxygen.

(11) When a functional monolayer stack is used in a multiple glazing unit 100 with a double glazing unit structure, as illustrated in FIG. 3, this glazing unit comprises two substrates 10, 30 which are held together by a chassis structure 90 and which are separated from one another by a gas separation layer 15.

(12) The glazing unit thus forms a separation between an external space ES and an internal space IS.

(13) The multilayer can be positioned on face 2 (on the sheet furthest toward the outside of the building considering the incident direction of the sunlight entering into the building and on its face turned toward the gas layer).

(14) FIG. 3 illustrates this positioning (the incident direction of the sunlight entering into the building being illustrated by the double arrow) on face 2 with a multilayer of thin films 14 positioned on an internal face 11 of the substrate 10 in contact with the gas separation layer 15, the other face 9 of the substrate 10 being in contact with the external space ES.

(15) However, it may also be envisioned, in this double glazing structure, for one of the substrates to have a laminar structure; however, there is no confusion possible because, in such a structure, there is no gas separation layer.

(16) Four examples have been implemented, numbered 1 to 4.

(17) Example 1 has been implemented following the teaching of the international patent application No. WO 2010/072974: the two dielectric coatings 120, 160 each comprise an absorbing layer 123, 165 which is disposed within the dielectric coating between two dielectric layers 122, 124; 164, 166, the absorbing material of the absorbing layers 123, 165 being disposed symmetrically on either side of the functional metal layer 140.

(18) The two dielectric layers 122, 124; 164, 166 which sandwich each absorbing layer are layers based on silicon nitride and a high index layer 126 is disposed on top of the layer 124, said high index layer 126 being in contact with an underlying wetting layer 128.

(19) The high index layer is an oxide-based layer; it has a refractive index in the range between 2.3 and 2.7, and which is here equal to 2.46 precisely.

(20) In this multilayer, the wetting layer 128 of zinc oxide doped with aluminum ZnO:Al (deposited from a metal target composed of zinc doped with 2% by weight of aluminum) allows the silver to crystallize which improves its conductivity.

(21) The overlying dielectric coating 160 comprises a dielectric layer 162 of zinc oxide doped with aluminum ZnO:Al (deposited from a metal target composed of zinc doped with 2% by weight of aluminum) and a protection layer 168 based on an oxide.

(22) The layers of silicon nitride 122, 124; 164, 166 are silicon nitride Si.sub.3N.sub.4 and are deposited from a metal target doped 8% by weight of aluminum.

(23) The absorbing layers 123, 165 are metal being titanium.

(24) For all the examples hereinafter, the deposition conditions for the layers are:

(25) TABLE-US-00001 Layer Target used Deposition pressure Gas Si.sub.3N.sub.4 Si:Al at 92:8% wt 1.5 .Math. 10.sup.?3 mbar Ar/(Ar + N2) at 45% TiO.sub.2 TiO.sub.x 2 .Math. 10.sup.?3 mbar Ar/(Ar + O2) at 90% Ti Ti 7 .Math. 10.sup.?3 mbar Ar at 100% ZnO Zn:Al at 98:2% wt 2 .Math. 10.sup.?3 mbar Ar/(Ar + O2) at 52% NiCr NiCr at 80:20 wt 2 .Math. 10.sup.?3 mbar Ar at 100% Ag Ag 2 .Math. 10.sup.?3 mbar Ar at 100%

(26) The deposited layers may thus be classified into four categories: ilayers of dielectric material, having a ratio n/k over the whole visible wavelength range greater than 5: Si.sub.3N.sub.4, TiO.sub.2, ZnO iilayers of absorbing material, having a ratio 0<n/k<5 over the whole visible wavelength range and a bulk electrical resistivity which is greater than 10.sup.?5 ?.Math.cm: Ti iiifunctional metal layers of a material with reflective properties in the infrared and/or in the solar radiation band: Ag. ivbarrier over- and underlayers designed to protect the functional layer against a modification of its nature during the deposition of the multilayer; their influence on the optical and energy properties is in general ignored.

(27) It has been observed that silver also has a ratio 0<n/k<5 over the whole visible wavelength range, but its bulk electrical resistivity is less than 10.sup.?5 ?.Math.cm.

(28) In all the examples hereinafter, the multilayer of thin films is deposited on a substrate made of clear soda-lime glass of the Planilux brand, distributed by the company SAINT-GOBAIN, with a thickness of 4 mm.

(29) For these substrates, R indicates: the resistance per square of the multilayer, in ohms per square; T.sub.L indicates: the light transmission in the visible in %, measured according to the illuminant D65 at 2?; a.sub.T* and b.sub.T* indicate: the colors in transmission a* and b* in the LAB system measured according to the illuminant D65 at 2?; R.sub.c indicates: the light reflection in the visible in %, measured according to the illuminant D65 at 2?, on the side of the substrate coated with the multilayer of thin films; a.sub.c* and b.sub.c* indicate: the colors in reflection a* and b* in the LAB system measured according to the illuminant D65 at 2?, on the side of the coated substrate; R.sub.g indicates: the light reflection in the visible in %, measured according to the illuminant D65 at 2?, on the side of the uncoated substrate; a.sub.g* and b.sub.g* indicate: the colors in reflection a* and b* in the LAB system measured according to the illuminant D65 at 2?, on the side of the uncoated substrate.

(30) Furthermore, for these examples, when the substrate carrying the multilayer is integrated into a double glazing unit, the latter has the structure: 4-16-4 (Ar90%), in other words two glass substrates, each having a thickness of 4 mm, are separated by a layer of gas composed of 90% argon and 10% air with a thickness of 16 mm.

(31) All these examples have, in this configuration of double glazing unit, allowed a coefficient U, or coefficient K, calculated according the standard EN 673, of the order of 1.0 W.Math.m.sup.?2.Math.? K.sup.?1 to be obtained (this is the heat transfer coefficient through the glazing unit; it denotes the quantity of heat passing through the substrate, in the stationary regime, per unit surface area and for a unit difference in temperature between the face of the glazing unit in contact with the external space and the face of the glazing unit in contact with the internal space).

(32) For these double-glazing units, FS indicates: the solar factor, in other words the ratio, in percent, of the total solar energy entering into the room through the glazing unit over the total incident solar energy; S indicates: the selectivity corresponding to the ratio of the light transmission T.sub.L in the visible over the solar factor FS such that: S=T.sub.Lvis/FS; T.sub.L indicates: the light transmission in the visible in %, measured according to the illuminant D65 at 2?; a.sub.T* and b.sub.T* indicate: the colors in transmission a* and b* in the LAB system measured according to the illuminant D65 at 2?; R.sub.e indicates: the external light reflection in the visible in %, measured according to the illuminant D65 at 2?, in the external space side ES; a.sub.e* and b.sub.e* indicate: the colors in external reflection a* and b* in the LAB system measured according to the illuminant D65 at 2?, in the external space side ES; R.sub.i indicates: the light reflection in the visible in %, measured according to the illuminant D65 at 2?, in the internal space side IS; a.sub.i* and b.sub.i* indicate: the colors in internal reflection a* and b* in the LAB system measured according to the illuminant D65 at 2?, in the internal space side IS.

(33) One example No. 1 has been implemented according to the multilayer structure illustrated in FIG. 1, with two absorbing layers 123 and 165 and an optional protection layer 168, but without an undercoating barrier 130.

(34) Table 1 hereinafter illustrates the geometrical or physical thicknesses (and not the optical thicknesses) in nanometers of each of the layers in example 1:

(35) TABLE-US-00002 TABLE 1 Layer Material Ex. 1 168 TiO.sub.2 1 166 Si.sub.3N.sub.4:Al 25.1 165 Ti 2.1 164 Si.sub.3N.sub.4:Al 25.1 162 ZnO:Al 9 150 NiCr 0.2 140 Ag 18.1 128 ZnO:Al 5 126 TiO.sub.2 12 124 Si.sub.3N.sub.4:Al 13.8 123 Ti 2.1 122 Si.sub.3N.sub.4:Al 13.8

(36) Table 2 hereinafter summarizes the main optical and energy characteristics of this example 1, respectively when only the substrate 10 alone is considered and when it is configured as a double glazing unit, on face 2, F2, as in FIG. 3.

(37) TABLE-US-00003 TABLE 2 R T.sub.L a.sub.T* b.sub.T* R.sub.c a.sub.c* b.sub.c* R.sub.g a.sub.g* b.sub.g* 10 1.9 40.89 ?3.49 4.74 16.41 ?0.33 ?25.8 18.94 4.06 ?5.81 FS s T.sub.L R.sub.e R.sub.i F2 27.26 1.37 37.38 20.35 21.86

(38) Thus, as can be seen in this table 2, the external light reflection R.sub.e of the glazing unit is of the order of 20% since the reflection on the glass side of the substrate is less than 19% and the color in external reflection is relatively neutral.

(39) The relatively low solar factor could allow a high selectivity to be attained, but as the light transmission in the visible T.sub.L is too low, in the end, the selectivity is relatively low.

(40) It is then desirable to obtain a higher light transmission, with a relatively low solar factor, in order to increase the selectivity while at the same time conserving an external reflection R.sub.e at a low value of around 20%, or even less as a double glazing unit, which is equivalent to an external reflection of the substrate alone, on the glass side, at a value less than or equal to 19%.

(41) An example 2 has subsequently been implemented on the basis of the multilayer illustrated in FIG. 2, by following the teaching of the invention and by thus disposing in the multilayer a single absorbing metal layer, here of titanium Ti, the layer 19, directly in contact with the substrate, then directly under a dielectric layer 122 based on a nitride not comprising any oxygen.

(42) Here, the dielectric layer 122 comprises silicon nitride but cannot be silicon oxynitride because such a material comprises oxygen.

(43) Table 3 hereinafter illustrates the geometrical thicknesses in nanometers of each of the layers in example 2:

(44) TABLE-US-00004 TABLE 3 Layer Material Ex. 2 168 TiO.sub.2 1 164 Si.sub.3N.sub.4:Al 44 162 ZnO:Al 9 150 NiCr 0.2 140 Ag 18.1 128 ZnO:Al 5 126 TiO.sub.2 12 122 Si.sub.3N.sub.4:Al 18.6 19 Ti 0.8

(45) This example 2 is thus substantially identical to example 1 with as main difference: the two absorbing layers 123 and 165 of 2.1 nanometers each in example 1 have been replaced by the single absorbing layer 19 with a thickness of 0.8 nm.

(46) Table 4 hereinafter summarizes the main optical and energy characteristics of this example 2, respectively when only the substrate 10 alone is considered and when the latter is configured as a double glazing unit F2, on face 2, as in FIG. 3. This table presents the same structure as table 2.

(47) TABLE-US-00005 TABLE 4 R T.sub.L a.sub.T* b.sub.T* R.sub.c a.sub.c* b.sub.c* R.sub.g a.sub.g* b.sub.g* 10 1.9 62.78 ?3.39 6.31 22.03 4.74 ?13.8 18.29 2.59 ?5.89 FS (%) s T.sub.L R.sub.e R.sub.i F2 38.35 1.5 57.66 21.2 26.5

(48) As can be seen in this table 4, the external light reflection R.sub.e is very satisfactory when the multilayer is positioned on face 2: it is around 21%.

(49) Similarly, the color seen from the outside has little difference from that of example 1 and remains neutral.

(50) Table 5 hereinafter illustrates the ranges of preferred physical thicknesses in nanometers, based on example 2:

(51) TABLE-US-00006 TABLE 5 Most-preferred Layer Material Preferred ranges ranges 168 TiO.sub.2 0.5-2 0.5-2 164 Si.sub.3N.sub.4:Al 35-50 35-50 162 ZnO:Al 5-10 5-10 150 NiCr 0.2-2.5 0.2-2.5 140 Ag 15-20 15-20 128 ZnO:Al 4-8 4-8 124 TiO.sub.2 5-15 5-15 122 Si.sub.3N.sub.4:Al 10-20 10-20 19 Ti 0.5-1.5 0.6-1.2

(52) Table 6 hereinafter summarizes the main optical and energy characteristics which may be respectively targeted with these preferred ranges and most-preferred ranges, respectively when only the substrate 10 is considered and when the latter is configured as a double glazing unit F2, on face 2, as in FIG. 3.

(53) TABLE-US-00007 TABLE 6 T.sub.L R.sub.g 10 preferred >60 <19 10 most preferred >62 <19 T.sub.L FS (%) s F2 preferred >55 <40 >1.45 F2 most preferred ?57 ?39 ?1.5

(54) As can be seen in this table 6, the light reflection of the substrate alone, coated with the multilayer, on the glass side, R.sub.g, is very satisfactory: it is less than 19%.

(55) The light transmission of the substrate coated with the multilayer is high; that of the double glazing unit is consequently also high.

(56) Although the solar factor is not very low, the selectivity is high.

(57) Furthermore, the color seen from the outside has little difference from that of example 1 and remains neutral.

(58) Two other examples, examples 3 and 4, have been implemented based on example 2 in order to illustrate what happens when the absorbing layer 19 is in contact with a layer of oxide, respectively for example 3 when the dielectric layer 122 is replaced by a layer of ZnO:Al, with an identical index (and with an identical optical thickness) and for example 4 when the dielectric layer 122 is eliminated and when the high index layer 126 is thickened (in order for the dielectric coating 120 underlying the functional layer to keep the same optical thickness).

(59) Examples 3 and 4 are thus identical to example 2 except in that: for example 3, the dielectric layer 122 of example 2 is replaced by a dielectric layer of the same material as the layers 128 and 162, in this case of ZnO:Al, this layer having a physical thickness of 18.6 nm; for example 4, the dielectric layer 122 in example 2 is eliminated and the high index layer 126, of TiO.sub.2, is thickened in order to reach a total physical thickness of 27.1 nm.

(60) Tables 7 and 8 hereinafter summarize the main optical and energy characteristics of these examples 3 and 4, respectively, when only the substrate 10 alone is considered and when the latter is configured as a double glazing unit F2, on face 2, as in FIG. 3. These tables each present the same structure as table 4.

(61) TABLE-US-00008 TABLE 7 example 3 R T.sub.L a.sub.T* b.sub.T* R.sub.c a.sub.c* b.sub.c* R.sub.g a.sub.g* b.sub.g* 10 1.9 61.5 ?2.7 5.0 24.2 3.1 ?11.1 22.1 0.8 ?3.4 FS (%) S T.sub.L R.sub.e R.sub.i F2 37.8 1.5 56.5 25.3 28.4

(62) As can be seen in this table 7, the light transmission of the coated substrate is degraded by the contact Ti/ZnO since it decreases by more than 1% with respect to that of example 2.

(63) Moreover, the light reflection on the glass side R.sub.g of the coated substrate is also degraded since it increases by almost 4%.

(64) Thus, if this example 3 is used in a double glazing unit, with the multilayer positioned on face 2, the selectivity is indeed conserved, but the light transmission T.sub.L is less than for example 2 (decrease of 1.5%) and the external light reflection R.sub.e increases (by 3.7%).

(65) Although the color of the double glazing unit seen from the outside is little different from that of example 2 and remains acceptable, the lower light transmission and the higher external reflection are not acceptable with regard to the objective sought.

(66) TABLE-US-00009 TABLE 8 example 4 R T.sub.L a.sub.T* b.sub.T* R.sub.c a.sub.c* b.sub.c* R.sub.g a.sub.g* b.sub.g* 10 1.9 64.8 ?4.2 8.9 19.1 7.6 ?19.3 14.4 6.1 ?10.5 FS (%) S T.sub.L R.sub.e R.sub.i F2 38.5 1.5 58.5 15.8 24.0

(67) As can be seen in this table 8, the light transmission of the coated substrate is improved by the contact Ti/TiO.sub.2 since it increases by 2% with respect to that of example 2.

(68) Moreover, the light reflection on the glass side R.sub.g of the substrate coated is also improved since it decreases by almost 4%.

(69) However, the color in transmission of the coated substrate is degraded, in particular due to the high value of b*.sub.t.

(70) Furthermore the color in reflection of the coated substrate on the uncoated side is degraded due to the high values (in absolute values) of a*.sub.g and b*.sub.g.

(71) The color in reflection of the coated substrate on the coated side is also degraded due to the high values (in absolute values) of a*.sub.c and b*.sub.c.

(72) Although the higher light transmission and the lower external reflection of example 4 with respect to example 2 would be acceptable with regard to the objective sought, the color of the double glazing unit seen from the outside is unacceptable.

(73) With the invention, it is possible to combine a high selectivity, a low emissivity and a low external light reflection with a multilayer comprising a single functional metal layer of silver or containing silver, while at the same time conserving a suitable esthetic appearance (the T.sub.L is greater than 60% and the colors are neutral in reflection).

(74) The use of only one absorbing layer simplifies the fabrication and reduces the cost with respect to the use of two absorbing layers; all the more so as the thickness of this single absorbing layer is less than the sum of the thicknesses of the two absorbing layers needed in the prior art.

(75) Furthermore, the mechanical resistance of the multilayer according to the invention is very high. Furthermore, the general resistance to chemical attack of this multilayer is overall very good.

(76) Furthermore, although this is not illustrated, it may be envisioned for a substrate 30 to comprise, on at least one face 29 in contact with the gas separation layer 15 and which does not comprise a multilayer of thin films with reflective properties in the infrared and/or in the solar radiation band, an antireflective coating which is facing said gas separation layer 15 with the multilayer of thin films 14 with reflective properties in the infrared and/or in the solar radiation band.

(77) The goal of this insertion of an antireflective coating in a double glazing unit structure is to allow a high light transmission and a high solar factor to be obtained.

(78) The present invention is described hereinabove by way of example. It is understood that those skilled in the art are able to construct many variants of the invention without however straying from the framework of the patent such as defined by the claims.