MATERIAL COMPRISING A SUBSTRATE PROVIDED WITH A STACK OF THIN LAYERS HAVING THERMAL PROPERTIES

Abstract

A material includes a transparent substrate coated with a stack of thin layers successively including an alternation of three silver-based functional metal layers and of four dielectric coatings so that each functional metal layer is positioned between two dielectric coatings. Absorbent material is present between the first functional layer and the second functional layer, in a total thickness Abs2 such that 1.0≤Abs2≤5.0 nm and/or absorbent material is present between the second functional layer and the third functional layer, in a total thickness Abs3 such that 1.0≤Abs3≤5.0 nm. Additionally, absorbent material is present between the face of the substrate and the first functional layer in a total thickness such that 0.0<Abs1≤0.5 nm and absorbent material is present above the third functional layer, in a total thickness Abs4 such that 0.0<Abs4≤0.5 nm.

Claims

1. A material comprising a transparent substrate coated on one face with a stack of thin layers successively comprising, starting from said face, an alternation: of three silver-based functional metal layers denoted, starting from the substrate, first functional layer Ag1, second functional layer Ag2 and third functional layer Ag3, with physical thicknesses respectively Ea1, Ea2 and Ea3, and of four dielectric coatings denoted, starting from said face of the substrate, M1, M2, M3 and M4, with optical thicknesses respectively Eo1, Eo2, Eo3 and Eo4, each dielectric coating comprising a dielectric layer or a dielectric assembly of layers, so that each functional metal layer is positioned between two dielectric coatings, wherein: absorbent material is present between said first functional layer Ag1 and said second functional layer Ag2, in a total thickness Abs2 such that 1.0≤Abs2≤5.0 nm and/or absorbent material is present between said second functional layer Ag2 and said third functional layer Ag3, in a total thickness Abs3 such that 1.0≤Abs≤5.0 nm; and absorbent material is present between said face of the substrate and said first functional layer Ag1 in a total thickness Abs1 such that 0.0<Abs1≤0.5 nm and absorbent material is present above said third functional layer Ag3, in a total thickness Abs4 such that 0.0<Abs4≤0.5 nm.

2. The material as claimed in claim 1, wherein the physical thicknesses Ea1 and the Ea2 respectively of said first and said second functional layers Ag1, Ag2 are each between 7.0 and 12.0 nm and the physical thickness Ea3 of said third functional layer Ag3 is between 13.0 and 16.0 nm.

3. The material as claimed in claim 1, wherein said absorbent material present between said first functional layer Ag1 and said second functional layer Ag2 is present in contact with said functional layer Ag2, with at least half of said total thickness Abs2 located in contact with said functional layer Ag2.

4. The material as claimed in claim 1, wherein said absorbent material present between said second functional layer Ag2 and said third functional layer Ag3 is present in contact with said functional layer Ag2, with at least half of said total thickness Abs3 located in contact with said functional layer Ag2.

5. The material as claimed claim 1, wherein said first dielectric coating M1 comprises a high-index layer, having a refractive index at 550 nm which is at least 2.15, and having an optical thickness Eo.sub.12 between 10.0 and 40.0 nm.

6. The material as claimed in claim 1, wherein said first dielectric coating M1 has an optical thickness Eo1 between 130.0 and 160.0 nm.

7. The material as claimed in claim 1, wherein said second dielectric coating M2 has an optical thickness Eo2 between 80.0 and 100.0 nm.

8. The material as claimed in claim 1, wherein said third dielectric coating M3 has an optical thickness Eo3 between 140.0 and 180.0 nm.

9. The material as claimed in claim 1, wherein said fourth dielectric coating M4 has an optical thickness Eo4 between 50.0 and 90.0 nm.

10. The material as claimed claim 1, wherein a ratio of the optical thickness Eo2 of said second dielectric coating M2 to the optical thickness Eo1 of said first dielectric coating M1 is equal to or greater than 0.4 and less than or equal to 0.9.

11. The material as claimed in claim 1, wherein a ratio of the optical thickness Eo1 of said first dielectric coating M1 to the optical thickness Eo4 of said fourth dielectric coating M4 is greater than 1.5.

12. The material as claimed in claim 1, wherein a ratio of the optical thickness Eo3 of said third dielectric coating M3 to the optical thickness Eo1 of said first dielectric coating M1 is between 0.9 and 1.1.

13. A glazing comprising: the material as claimed in claim 1.

14. The glazing as claimed in claim 13, wherein the glazing is a double glazing having a light transmission T.sub.L of 40.0%≤T.sub.L≤55.0%, an external reflection R.sub.e of at least 27.0% and an internal reflection R.sub.i of 20.0% or less.

15. The glazing as claimed in claim 13, wherein the glazing is a laminated or multiple glazing.

16. The glazing as claimed in claim 13, wherein the glazing is a triple glazing.

17. The material as claimed in claim 1, wherein said absorbent material present between said first functional layer Ag1 and said second functional layer Ag2 is present in contact with said functional layer Ag2, with all of said total thickness Abs2 located in contact with said functional layer Ag2.

18. The material as claimed in claim 1, wherein said absorbent material present between said second functional layer Ag2 and said third functional layer Ag3 is present in contact with said functional layer Ag2, with all of said total thickness Abs3 located in contact with said functional layer Ag2.

19. The material as claimed in claim 1, wherein only said first dielectric coating M1 comprises a high-index layer, having a refractive index at 550 nm which is at least 2.15, and having an optical thickness Eo.sub.12 between 10.0 and 40.0 nm.

20. The material as claimed in claim 1, wherein a ratio of the optical thickness Eo1 of said first dielectric coating M1 to the optical thickness Eo4 of said fourth dielectric coating M4 is greater than 2.0.

Description

[0168] The details and advantageous characteristics of the invention emerge from the following nonlimiting examples, illustrated by means of the appended FIG. 1. In this FIGURE, the proportions between the various components are not respected in order to make the FIGURE easier to read.

[0169] FIG. 1 illustrates a stack structure according to the invention comprising only three functional metal layers 40, 80, 120, this structure being deposited on a transparent glass substrate 10. Each functional layer 40, 80, 120 is positioned between two dielectric coatings 20, 60, 100, 140 so that: [0170] the first functional layer 40 (or “Ag1”) is positioned between a first dielectric coating 20 (or “M1”) and a second dielectric coating 60 (or “M2”), [0171] the second functional layer 80 (or “Ag2”) is positioned between the second dielectric coating 60 (or “M2”) and a third dielectric coating 100 (or “M3”) and [0172] the third functional layer 120 (or “Ag3”) is positioned between the third dielectric coating 100 (or “M3”) and a fourth, or final, dielectric coating 140 (or “M4”).

[0173] These dielectric coatings 20, 60, 100, 140 each comprise at least one dielectric layer 22, 23, 24, 27, 28; 62, 64, 68; 102, 104, 107, 108; 142, 144.

[0174] The stack may also comprise: [0175] blocking underlayers 30, 70 located in contact with a functional layer, [0176] blocking overlayers 50, 90 and 130 located in contact with a functional layer, [0177] a protective layer 160, for example made of TiZr or of titanium zirconium oxide.

EXAMPLES

[0178] Stacks of thin layers defined below are deposited on substrates made of clear soda-lime glass with a thickness of 6 mm.

[0179] In the examples: [0180] the functional layers 40, 80 and 120 are silver (“Ag”) layers, [0181] the blocking layers 30, 50, 70, 90 and 130 are metal layers made of an alloy of nickel and of chromium (“NiCr”), [0182] the dielectric layers 22, 23, 24, 27, 28; 62, 64, 68; 102, 104, 107, 108; 142, 144 are: [0183] for the layers 22, 24, 64, 104 and 144, made of aluminum-doped silicon nitride, Si.sub.3N.sub.4 (“SiN”), [0184] for the layer 23, made of aluminum-doped silicon zirconium nitride (“SiZrN”), [0185] for the layers 28, 62, 68, 102, 108 and 142, made of aluminum-doped zinc oxide (“ZnO”) [0186] for the layers 27, and 107, made of zinc tin oxide (“SnZnO”) [0187] the absorbent layers 26, 66, 106 and 146 consist of the same material as the blocking layers; they are metal absorbent layers made of an alloy of nickel and chromium (for NiCr, k=3.0 at 550 nm).

[0188] The conditions for deposition of the layers, which were deposited by sputtering (“magnetron cathode” sputtering), are summarized in table 1.

TABLE-US-00001 TABLE 1 n at Target employed Deposition pressure Gas 550 nm SiN Si:Al at 92:8 (wt %) 3.2 × 10.sup.−3 mbar Ar/(Ar + N.sub.2) at 55% 2.03 SiZrN Si (73 at. %); Zr (27 at. %) 3-4 × 10.sup.−3 mbar Ar/(Ar + N.sub.2) at 55% 2.38 ZnO Zn:Al at 98:2 (wt %) 1.8 × 10.sup.−3 mbar Ar/(Ar + O.sub.2) at 63% 1.95 SnZnO Sn—Zn at 50:50 (wt %) 3.1 × 10.sup.−3 mbar Ar/(Ar + O.sub.2) at 66% 2.18 NiCr Ni (80 at. %); Cr (20 at. %) 2-3 × 10.sup.−3 mbar Ar at 100% 2.50 NbN Nb 2 × 10.sup.−3 mbar Ar/(Ar + N.sub.2) at 60% 3.80 NiCrN Ni (80 at. %); Cr (20 at. %) 3.5 × 10.sup.−3 mbar Ar/(Ar + N.sub.2) at 34% 3.0  Ag Ag 3 × 10.sup.−3 mbar Ar at 100% — At. = atomic

[0189] Table 2 lists the materials and the physical thicknesses in nanometers (unless otherwise indicated) of each layer and the corresponding optical thickness (in nanometers) of each dielectric coating as a function of their position with regard to the substrate bearing the stack (final row at the bottom of the table) for a series of examples 1 to 8.

TABLE-US-00002 TABLE 2 Layer no. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 in FIG. 1 ref comp inv inv comp inv inv comp Eo4 of M4 with 140 76 76 76   76   76 76   80   80 Ep (NiCr) 146 1 Ep (Si.sub.3N.sub.4) 144 33.2 33.2 33.2  33.2  33.2 33.2  30.6  32.0 Ep (ZnO) 142 5.0 5.0 5.0 5.0 5.0 5.0 10.0  8.0 Ep OB3 (NiCr) 130 0.2 0.2 0.2 0.2 0.2 0.2 0.3 0.6 Ep (Ag3) 120 14.3 14.3 14.3  14.3  14.3 14.3  15.2  18.0 Eo3 of M3 with: 100 150 150 150    150    150 150    156    173 Ep (ZnO) 108 5.0 5.0 5.0 5.0 5.0 5.0 4.0 8.0 Ep (SnZnO) 107 5.0 5.0 5.0 5.0 5.0 5.0 4.0 8.0 Ep (NiCr) 106 1   1   Ep (Si.sub.3N.sub.4) 104 60.0 60.0 60.0  60.0  60.0 60.0  60.8  62.0 Ep (ZnO) 102 5.0 5.0 5.0 5.0 5.0 5.0 10.0  8.0 Ep OB2 (NiCr) 90 0.2 0.2 0.2 0.2 0.2 0.2 0.5 0.5 Ep Ag2 80 10.0 10.0 10.0  10.0  10.0 10.0  10.3  18.0 Ep UB2 (NiCr) 70 0.5 0.5 0.5 0.5 0.5 0.5 1.5 0.1 Eo2 of M2 with: 60 77 77 77   77   77 77   90   122 Ep (ZnO) 68 5.0 5.0 5.0 5.0 5.0 5.0 4.0 8.0 Ep (NiCr) 66 1   1   Ep (Si.sub.3N.sub.4) 64 28.6 28.6 28.6  28.6  28.6 28.6  37.3  45.0 Ep (ZnO) 62 5.0 5.0 5.0 5.0 5.0 5.0 4.0 8.0 Ep OB1 (NiCr) 50 0.2 0.2 0.2 0.2 0.2 0.2 0.2 1.4 Ep Ag1 40 10.0 10.0 10.0  10.0  10.0 10.0  10.0  10.0 Ep UB1 (NiCr) 30 0.3 0.3 0.3 0.3 0.3 0.3 0.1 0.7 Eo1 of M1 with: 20 154 154 154    154    154 154    152    95 Ep (ZnO) 28 5.0 5.0 5.0 5.0 5.0 5.0 4.0 8.0 Ep (SnZnO) 27 8.7 8.7 8.7 8.7 8.7 8.7 4.7 Ep (NiCr) 26 1 Ep (Si.sub.3N.sub.4) 24 25.0 25.0 25.0  25.0  25.0 25.0  30.0  Ep (SiZrN) 23 15.6 15.6 15.6  15.6  15.6 15.6  6.3 Ep (Si.sub.3N.sub.4) 22 19.3 19.3 19.3  19.3  19.3 19.3  30.0  40 Glass substrate (mm) 6 6 6 6   6   6 6   6   6 *Ep: Physical thickness (nm); Eo: Optical thickness (nm).

[0190] Example 1 is the reference example (“ref”); i.e. the example which is used as a basis for explaining the invention. Examples 3, 4, 6 and 7 are examples according to the invention (“inv”). The comparative examples 2, 5 and 8 are examples outside of the invention (“comp”).

[0191] Examples 1 to 8 are examples having three silver-based functional metal layers.

[0192] Table 3 lists the main optical characteristics measured when the stacks form part of a double glazing of 6/16/4 structure: (external) 6-mm glass/16-mm interlayer space filled with 90% argon/4-mm glass (internal), the stack being positioned on face 2 (face 1 of the glazing being the outermost face of the glazing, as usual).

[0193] For these double glazings, [0194] T.sub.L indicates: the light transmission in the visible region in %, measured according to the illuminant D65 at 2° observer; [0195] a*.sub.T and b*.sub.T indicate the colors at normal incidence (0°) in transmission a* and b* in the L*a*b* system, measured according to the illuminant D65 at 2° observer and measured perpendicularly to the glazing; [0196] R.sub.e indicates: the light reflection in the visible region in %, measured according to the illuminant D65 at 2° observer on the side of the outermost face, face 1; [0197] a*R.sub.e and b*R.sub.e indicate the colors at normal incidence (0°) in reflection a* and b* in the L*a*b* system, measured according to the illuminant D65 at 2° observer on the side of the outermost face and thus measured perpendicularly to the glazing, [0198] R.sub.i indicates: the light reflection in the visible region in %, measured according to the illuminant D65 at 2° observer on the side of the interior face, face 4; [0199] a*.sub.Ri and b*.sub.Ri indicate the colors at normal incidence (0°) in reflection a* and b* in the L*a*b* system, measured according to the illuminant D65 at 2° observer on the side of the interior face and thus measured perpendicularly to the glazing; [0200] a*(60°) and b*(60°) indicate the colors a* and b* in reflection in the L*a*b* system, measured at 60° incidence with respect to the normal according to the illuminant D65 at 2° observer on the glass side, on the opposite side to the stack, for the (monolithic) substrate alone.

[0201] The target values indicated below are the values which are preferred simultaneously for the invention, in a very successful version of the invention.

TABLE-US-00003 TABLE 3 Target Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 value (ref) (comp) (inv) (inv) (comp) (inv) (inv) (comp) Solar 0.26 0.22 0.23 0.23 0.24 0.21 0.26 0.21 factors “g” Selectivity ≥1.8 1.88 1.92 1.93 1.85 1.86 1.88 1.83 2.24 “s” T.sub.L(%) 50 49 43 45 42 45 39 48 47 a*.sub.T <0 −3.6 −1.3 −8.2 −3.5 −3.8 −7.6 −4.9 −8.0 b*.sub.T   {−5.0; 1.0} −0.4 1.5 −1.6 −2.7 −0.8 −4.4 −0.1 1.0 R.sub.e(%) ≥28 32 31 30 35 28 33 29 16 a*.sub.Re {−5.0; 0} −3.6 −10.8 −2.5 −4.2 −4.0 −1.0 −2.1 −5.0 b*.sub.Re {−8.0; 0} −2.0 −4.6 −4.2 −4.1 −3.5 −1.6 −5.2 −9.0 R.sub.i(%) ≤20 26 26 20 20 28 19 20 18 a*.sub.Ri {−7.0; 0} −8.5 −24.3 −6.4 −7.0 −8.8 −3.4 −3.6 −11.0 b*.sub.Ri {−8.0; 0} −0.5 12.9 −12.6 −2.5 −0.4 −6.0 −6.2 −10.0 a*(60°) 0.6 6.4 7.1 0.2 −1.1 5.6 −4.7 −4.5 b*(60°) 10.5 −17.5 −8.3 −9.4 −10.1 −7.3 −7.7 −3.0

[0202] According to the invention, it is possible to produce a glazing comprising a stack having three functional metal layers which has a low light transmission T.sub.L of the order of 50% (between 40% and 55%, including these values), with a high external reflection R.sub.e of the order of at least 27% (between 27% and 35%, including these values) and a low internal reflection R.sub.i of the order of 20% or less (between 5% and 20%, including these values), with a selectivity S≥1.8 for a double glazing with the stack of thin layers on face 2. Examples 3, 4, 6 and 7 all have all these features, owing in particular to the specific layers made of absorbent material which are underlined in the table: [0203] for example 3 owing to the fact that the absorbent material is present between the second functional layer 80 and the third functional layer 120, these are the layers 90 and 106, in a total thickness of 1.2 nm and to the fact that the absorbent material is present between the face of the substrate and the first functional layer 40, this is the layer 30, in a total thickness of only 0.3 nm and absorbent material is present above the third functional layer 120, this is the layer 130, in a total thickness of only 0.2 nm; [0204] for example 4 owing to the fact that the absorbent material is present between the first functional layer 40 and the second functional layer 80, these are the layers 50, 66 and 70, in a total thickness of 1.7 nm and to the fact that absorbent material is present between the face of the substrate and the first functional layer 40, this is the layer 30, in a total thickness of only 0.3 nm and absorbent material is present above the third functional layer 120, this is the layer 130, in a total thickness of only 0.2 nm; [0205] for example 6 owing to the fact that the absorbent material is present between said first functional layer 40 and said second functional layer 80, these are the layers 50, 66 and 70, in a total thickness of 1.7 nm and absorbent material is present between the second functional layer 80 and the third functional layer 120, these are the layers 90 and 106, in a total thickness of 1.2 nm and to the fact that absorbent material is present between the face of the substrate and the first functional layer 40, this is the layer 30, in a total thickness of only 0.3 nm and absorbent material is present above the third functional layer 120, this is the layer 130, in a total thickness of only 0.2 nm; [0206] for example 7 owing to the fact that the absorbent material is present between said first functional layer 40 and said second functional layer 80, these are the layers 50 and 70, in a total thickness of 1.7 nm and to the fact that absorbent material is present between the face of the substrate and the first functional layer 40, this is the layer 30, in a total thickness of only 0.3 nm and absorbent material is present above the third functional layer 120, this is the layer 130, in a total thickness of only 0.2 nm.

[0207] For these examples according to the invention, it should be noted that the absorbent material is present in a relatively large thickness between the first and the second functional layers and/or between the second and the third functional layers whereas it is present in a relatively small thickness below the first functional layer and above the third functional layer; it is this particular distribution of the absorbent material which makes it possible to obtain a glazing simultaneously having a low light transmission of the order of 50%, a high external reflection R.sub.e of the order of at least 27% and a low internal reflection R.sub.i of the order of 20% or less.

[0208] Examples 1, 2, 5 and 8 do not make it possible to produce a glazing which has a low light transmission T.sub.L of the order of 50% (between 40% and 55%, including these values), with a high external reflection R.sub.e of the order of at least 27% (between 27% and 35%, including these values) and a low internal reflection R.sub.i of the order of 20% or less (between 5% and 20%, including these values), with a selectivity S≥1.8: [0209] for example 1 owing to the fact that there is not enough absorbent material in the stack; [0210] for example 2 owing to the fact that the absorbent material, that of the layer 146, is positioned completely over the stack, as final layer; [0211] for example 5 owing to the fact that the absorbent material, that of the layer 26, is positioned in the first dielectric coating 20; [0212] for example 8 owing to the fact that there is too much absorbent material between the substrate and the first functional metal layer 40 (the layer 30 of 0.7 nm) and too much absorbent material above the third functional metal layer 120 (the layer 130 of 0.6 nm).

[0213] Examples 3, 4, 6 and 7 according to the invention all have a pleasant and very weak coloration in transmission, preferably in the range of the blues or blue-greens, but of very low strength.

[0214] Table 4 lists the materials and the physical thicknesses in nanometers (unless otherwise indicated) of each layer and the corresponding optical thickness (in nanometers) of each dielectric coating as a function of their position with regard to the substrate bearing the stack (final row at the bottom of the table) for a series of examples 10 to 20.

TABLE-US-00004 TABLE 4 Layer no. Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 in FIG. 1 ref comp comp inv inv inv Eo4 of M4 with 140 80.3 80.3 80.3 80.3 80.3 80.3 Ep (Si.sub.3N.sub.4) 144 30.6 30.6 30.6 30.6 30.6 30.6 Ep (ZnO) 142 10.0 10.0 10.0 10.0 10.0 10.0 Ep OB3 (NiCr) 130 0.3 0.3 1.3  0.3  0.3  0.3 Ep (Ag3) 120 15.2 15.2 15.2 15.2 15.2 15.2 Eo3 of M3 with: 100 156.1 156.1 156.1 156.1  156.1  156.1  Ep (ZnO) 108 4.0 4.0 4.0  4.0  4.0  4.0 Ep (SnZnO) 107 4.0 4.0 4.0  4.0  4.0  4.0 Ep (NiCr) 106 Ep (Si.sub.3N.sub.4) 104 61 61 61 61   61   61   Ep (ZnO) 102 10.0 10.0 10.0 10.0 10.0 10.0 Ep OB2 (NiCr) 90 0.25 0.25 0.25  0.25  1.25  0.25 Ep Ag2 80 10.5 10.5 10.5 10.5 10.5 10.5 Ep UB2 (NiCr) 70 0.5 0.5 0.5  1.5  0.5  0.5 Eo2 of M2 with: 60 89.5 89.5 89.5 89.5 89.5 89.5 Ep (ZnO) 68 4.0 4.0 4.0  4.0  4.0  4.0 Ep (NiCr) 66  1.0 Ep (Si.sub.3N.sub.4) 64 37.0 37.0 37.0 37.0 37.0 37.0 Ep (ZnO) 62 4.0 4.0 4.0  4.0  4.0  4.0 Ep OB1 (NiCr) 50 0.15 0.15 0.15  0.15  0.15  0.15 Ep Ag1 40 10.0 10.0 10.0 10.0 10.0 10.0 Ep UB1 (NiCr) 30 0.15 1.15 0.15  0.15  0.15  0.15 Eo1 of M1 with: 20 151.7 151.7 151.7 151.7  151.7  151.7  Ep (ZnO) 28 4.0 4.0 4.0  4.0  4.0  4.0 Ep (SnZnO) 27 4.7 4.7 4.7  4.7  4.7  4.7 Ep (Si.sub.3N.sub.4) 24 30.0 30.0 30.0 30.0 30.0 30.0 Ep (SiZrN) 23 6.0 6.0 6.0  6.0  6.0  6.0 Ep (Si.sub.3N.sub.4) 22 30.0 30.0 30.0 30.0 30.0 30.0 Glass substrate (mm) 6 6 6 6 6  6  6  Layer no. Ex. 10 Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 20 in FIG. 1 ref inv inv inv comp inv Eo4 of M4 with 140 80.3 80.3 80.3 80.3 80.3 80.3 Ep (Si.sub.3N.sub.4) 144 30.6 30.6 30.6 30.6 30.6 30.6 Ep (ZnO) 142 10.0 10.0 10.0 10.0 10.0 10.0 Ep OB3 (NiCr) 130 0.3  0.3  0.3  0.3 0.3  0.3 Ep (Ag3) 120 15.2 15.2 15.2 15.2 15.2 15.2 Eo3 of M3 with: 100 156.1 156.1  156.1  156.1  156.1 156.1  Ep (ZnO) 108 4.0  4.0  4.0  4.0 4.0  4.0 Ep (SnZnO) 107 4.0  4.0  4.0  4.0 4.0  4.0 Ep (NiCr) 106  0.5 Ep (Si.sub.3N.sub.4) 104 61 61   61   61   61 61   Ep (ZnO) 102 10.0 10.0 10.0 10.0 10.0 10.0 Ep OB2 (NiCr) 90 0.25  0.25  0.25  0.25 0.25  0.75 Ep Ag2 80 10.5 10.5 10.5 10.5 10.5 10.5 Ep UB2 (NiCr) 70 0.5  1.0  1.0  1.0 0.8  1.0 Eo2 of M2 with: 60 89.5 89.5 89.5 89.5 89.5 89.5 Ep (ZnO) 68 4.0  4.0  4.0  4.0 4.0  4.0 Ep (NiCr) 66  0.5 Ep (Si.sub.3N.sub.4) 64 37.0 37.0 37.0 37.0 37.0 37.0 Ep (ZnO) 62 4.0  4.0  4.0  4.0 4.0  4.0 Ep OB1 (NiCr) 50 0.15  0.15  0.15  0.15 0.15  0.15 Ep Ag1 40 10.0 10.0 10.0 10.0 10.0 10.0 Ep UB1 (NiCr) 30 0.15  0.15  0.15  0.15 0.15  0.15 Eo1 of M1 with: 20 151.7 151.7  151.7  151.7  151.7 151.7  Ep (ZnO) 28 4.0  4.0  4.0  4.0 4.0  4.0 Ep (SnZnO) 27 4.7  4.7  4.7  4.7 4.7  4.7 Ep (Si.sub.3N.sub.4) 24 30.0 30.0 30.0 30.0 30.0 30.0 Ep (SiZrN) 23 6.0  6.0  6.0  6.0 6.0  6.0 Ep (Si.sub.3N.sub.4) 22 30.0 30.0 30.0 30.0 30.0 30.0 Glass substrate (mm) 6 6 6  6  6  6 6  *Ep: Physical thickness (nm); Eo: Optical thickness (nm).

[0215] Table 5 lists the main optical characteristics measured, like for table 3, when the stacks form part of a double glazing of 6/16/4 structure: (external) 6-mm glass/16-mm interlayer space filled with 90% argon/4-mm glass (internal), the stack being positioned on face 2 (face 1 of the glazing being the outermost face of the glazing, as usual).

TABLE-US-00005 TABLE 5 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 20 ref comp comp inv inv inv inv inv inv comp inv g 29.1 26.5 26.7 26.1 26.0 25.8 25.9 26.0 27.5 28.1 26 s 1.87 1.86 1.93 1.84 1.83 1.85 1.85 1.89 1.86 1.86 1.83 T.sub.L(%) 54.3 49.2 51.6 48.0 47.5 47.7 47.8 49.2 51.1 52.3 47.7 a*.sub.T −4.4 −4.5 −6.2 −4.9 −4.9 −4.8 −4.9 −6.6 −4.7 −4.6 −4.9 b*.sub.T 3.4 3.8 5.6 −0.1 −1.2 0.3 0.1 1.6 1.6 2.3 −0.6 R.sub.e(%) 26.8 26.3 25.0 29.2 29.4 29.7 29.6 26.9 28.2 27.7 29.5 a*.sub.Re −2.5 −3.5 −1.1 −2.1 −1.9 −2.3 −2.2 0.2 −2.3 −2.3 −2.0 b*.sub.Re −8.7 −8.5 −15.1 −5.2 −3.7 −5.7 −5.5 −9.1 −7.0 −7.7 −4.5 R.sub.i(%) 22.0 23.8 21.2 19.7 18.8 20.0 19.8 19.0 20.0 21.1 19.1 a*.sub.Ri −6.5 −6.9 −12.4 −3.6 −3.1 −3.8 −3.7 −5.8 −5.0 −5.6 −3.3 b*.sub.Ri −7.9 −7.7 −7.8 −6.2 −7.6 −6.0 −6.1 −11.9 −7.2 −7.5 −6.9 a*(60°) −5.9 −7.5 1.0 −4.7 −4.3 −5.9 −4.8 −1.4 −5.2 −5.4 −4.4 b*(60°) −9.6 −9.3 −14.2 −7.7 −6.5 −9.7 −8.0 −8.5 −8.7 −9.1 −7.1

[0216] According to the invention, it is possible to produce a glazing comprising a stack having three functional metal layers which has a low light transmission T.sub.L of the order of 50% (between 40% and 55%, including these values), with a high external reflection R.sub.e of the order of at least 27% (between 27% and 35%, including these values) and a low internal reflection R.sub.i of the order of 20% or less (between 5% and 20%, including these values), with a selectivity S≥1.8 for a double glazing with the stack of thin layers on face 2. Examples 13 to 18 and 20 all have all these features, owing in particular to the specific layers made of absorbent material which are underlined in the table: [0217] for example 13 owing to the fact that absorbent material is present between the first functional layer 40 and the second functional layer 80, these are the layers 50 and 70, in a total thickness of 1.65 nm and to the fact that absorbent material is present between the face of the substrate and the first functional layer 40, this is the layer 30, in a total thickness of only 0.15 nm and absorbent material is present above the third functional layer 120, this is the layer 130, in a total thickness of only 0.3 nm; [0218] for example 14 owing to the fact that de the absorbent material is present between the second functional layer 80 and the third functional layer 120, this is the layer 90, in a total thickness of 1.25 nm and to the fact that absorbent material is present between the face of the substrate and the first functional layer 40, this is the layer 30, in a total thickness of only 0.15 nm and absorbent material is present above the third functional layer 120, this is the layer 130, in a total thickness of only 0.3 nm; [0219] for example 15 owing to the fact that absorbent material is present between the first functional layer 40 and the second functional layer 80, these are the layers 50, 66 and 70, in a total thickness of 1.65 nm and to the fact that absorbent material is present between the face of the substrate and the first functional layer 40, this is the layer 30, in a total thickness of only 0.15 nm and absorbent material is present above the third functional layer 120, this is the layer 130, in a total thickness of only 0.3 nm; [0220] for example 16 owing to the fact that absorbent material is present between the first functional layer 40 and the second functional layer 80, these are the layers 50, 66 and 70, in a total thickness of 1.65 nm and to the fact that absorbent material is present between the face of the substrate and the first functional layer 40, this is the layer 30, in a total thickness of only 0.15 nm and absorbent material is present above the third functional layer 120, this is the layer 130, in a total thickness of only 0.3 nm; [0221] for example 17 owing to the fact that absorbent material is present between the first functional layer 40 and the second functional layer 80, these are the layers 50 and 70, in a total thickness of 1.15 nm and to the fact that absorbent material is present between the face of the substrate and the first functional layer 40, this is the layer 30, in a total thickness of only 0.15 nm and absorbent material is present above the third functional layer 120, this is the layer 130, in a total thickness of only 0.3 nm; this example 17 further comprising an absorbent layer 106 in the third dielectric coating; [0222] for example 18 owing to the fact that absorbent material is present between the first functional layer 40 and the second functional layer 80, these are the layers 50 and 70, in a total thickness of 1.15 nm and to the fact that absorbent material is present between the face of the substrate and the first functional layer 40, this is the layer 30, in a total thickness of only 0.15 nm and absorbent material is present above the third functional layer 120, this is the layer 130, in a total thickness of only 0.3 nm; and [0223] for example 20 owing to the fact that absorbent material is present between the first functional layer 40 and the second functional layer 80, these are the layers 50, 66 and 70, in a total thickness of 1.15 nm and to the fact that absorbent material is present between the face of the substrate and the first functional layer 40, this is the layer 30, in a total thickness of only 0.15 nm and absorbent material is present above the third functional layer 120, this is the layer 130, in a total thickness of only 0.3 nm.

[0224] Examples 10 to 12 and 19 do not make it possible to produce a glazing which has a low light transmission T.sub.L of the order of 50% (between 40% and 55%, including these values), with a high external reflection R.sub.e of the order of at least 27% (between 27% and 35%, including these values) and a low internal reflection R.sub.i of the order of 20% or less (between 5% and 20%, including these values), with a selectivity S≥1.8: [0225] for example 10 owing to the fact that there is not enough absorbent material in the stack; [0226] for example 11 owing to the fact that the absorbent material, that of the layer 30, is positioned below the first functional metal layer 20; [0227] for example 12 owing to the fact that the absorbent material, that of the layer 130, is positioned above the third functional metal layer 120; [0228] for example 19 owing to the fact that there is not enough absorbent material between the first functional metal layer 40 and the second functional metal layer 80.

[0229] Two additional examples were carried out on the basis of example 15, replacing the layer 64, made of absorbent material, of 1 nm of NiCr with: [0230] a layer 64, made of absorbent material, of 1 nm of NbN (example 21; k=2.9 at 550 nm) and [0231] a layer 64, made of absorbent material, of 1 nm of NiCrN (example 22; k=3.3 at 550 nm).

[0232] These examples made it possible to produce a glazing of the same type as that of tables 3 and 5 having: [0233] a low light transmission T.sub.L of 50.2% (example 21) and of 46.1% (example 22), [0234] a high external reflection R.sub.e of 27.8% (example 21) and of 29.2% (example 22), [0235] a low internal reflection R.sub.i of 19.2% (example 21) and of 17.2% (example 22), [0236] a high solar factor “g” of 27.4% (example 21) and of 25.5% (example 22), and [0237] a high selectivity “s” of 1.83 (example 21) and of 1.81 (example 22).

[0238] Another series of examples was carried out with distributions of thicknesses of the functional layers which are different.

[0239] Table 6 lists the materials and the physical thicknesses in nanometers (unless otherwise indicated) of each layer and the corresponding optical thickness (in nanometers) of each dielectric coating as a function of their position with regard to the substrate bearing the stack (final row at the bottom of the table) for a series of examples 21 to 26.

TABLE-US-00006 TABLE 6 Layer no. Ex. 21 Ex. 22 Ex. 23 Ex. 24 Ex. 25 Ex. 26 in FIG. 1 inv comp comp inv comp comp Eo4 of M4 with 140 79.0 79.0 95.0 79.0 79.0 90.0 Ep (Si.sub.3N.sub.4) 144 34.3 34.3 42.3 34.4 34.4 39.9 Ep (ZnO) 142 5.0 5.0 5.0 5.0 5.0 5.0 Ep OB3 (NiCr) 130 0.2 1.5 1.5 0.3 1.5 1.5 Ep (Ag3) 120 16.0 16.0 16.0 15.0 15.0 15.0 Eo3 of M3 with: 100 153 153 163 145 145 157 Ep (ZnO) 108 5.0 5.0 5.0 5.0 5.0 5.0 Ep (SnZnO) 107 5.0 5.0 5.0 5.0 5.0 5.0 Ep (Si.sub.3N.sub.4) 104 61.5 61.5 66.6 57.3 57.3 63.5 Ep (ZnO) 102 5.0 5.0 5.0 5.0 5.0 5.0 Ep OB2 (NiCr) 90 0.2 0.2 0.2 0.2 0.2 0.2 Ep Ag2 80 12.0 12.0 12.0 8.0 8.0 8.0 Ep UB2 (NiCr) 70 1.5 0.2 0.2 1.5 0.2 0.2 Eo2 of M2 with: 60 94 94 82 87 87 77 Ep (ZnO) 68 5.0 5.0 5.0 5.0 5.0 5.0 Ep (Si.sub.3N.sub.4) 64 36.8 36.8 31.2 33.3 33.3 28.3 Ep (ZnO) 62 5.0 5.0 5.0 5.0 5.0 5.0 Ep OB1 (NiCr) 50 0.2 0.2 0.2 0.2 0.2 0.2 Ep Ag1 40 8.0 8.0 8.0 10.0 10.0 10.0 Ep UB1 (NiCr) 30 0.3 0.3 0.3 0.3 0.3 0.3 Eo1 of M1 with: 20 148 148 220 151 151 253 Ep (ZnO) 28 5.0 5.0 5.0 5.0 5.0 5.0 Ep (SnZnO) 27 9.0 9.0 9.0 9.0 9.0 9.0 Ep (Si.sub.3N.sub.4) 24 25.0 25.0 50.0 32.8 32.8 47.1 Ep (SiZrN) 23 15.6 15.6 15.6 15.6 15.6 15.6 Ep (Si.sub.3N.sub.4) 22 19.3 19.3 30.0 13.3 13.3 50.0 Glass substrate (mm) 6 6 6 6 6 6 6 *Ep: Physical thickness (nm); Eo: Optical thickness (nm).

[0240] Table 7 lists the main optical characteristics measured, like for tables 3 and 5, when the stacks form part of a double glazing of 6/16/4 structure: (external) 6-mm glass/16-mm interlayer space filled with 90% argon/4-mm glass (internal), the stack being positioned on face 2 (face 1 of the glazing being the outermost face of the glazing, as usual).

TABLE-US-00007 TABLE 7 More Preferred preferred Ex. 21 Ex. 22 Ex. 23 Ex. 24 Ex. 25 Ex. 26 values values inv comp comp inv comp comp g 25.2 25.8 24.4 25.7 26.8 26.6 s 1.9 2.0 2.1 1.8 2.0 1.9 T.sub.L(%) ≥55.0 47.1 51.9 50.4 46.9 52.5 51.6 ≤40.0 a*.sub.T <0 −6.0 −9.5 −8.1 −5.7 −8.0 −5.7 b*.sub.T .sup. {−5.0; 1.0} −3.2 4.0 1.8 −0.2 8.3 0.7 R.sub.e(%) ≥27.0 28.1 22.6 27.0 28.3 22.9 26.1 a*.sub.Re {−5.0; 0} −2.2 3.6 −2.0 −1.8 1.6 −3.7 b*.sub.Re {−8.0; 0} −0.3 −13.5 −1.1 −6.9 −20.4 −2.0 R.sub.i(%) ≤20.0 20.0 22.6 22 17.6 20.3 21 a*.sub.Ri {−7.0; 0} −0.2 −12.7 −4.7 −0.1 −12.8 −6.1 b*.sub.Ri {−8.0; 0} −1.4 −6.8 −8.0 −8 −11.0 −5.0 a*(60°) 2.3 13.3 5.0 −0.5 7.9 −2.6 b*(60°) −6.0 −12.2 −3.3 −10.0 −18.3 −2.8

[0241] Example 21 according to the invention differs from the preceding examples by a different distribution of the thickness of the functional metal layers: the first functional metal layer is thinner than before, the second functional metal layer is thicker than the first and the third functional metal layer is thicker than the second.

[0242] Example 24 according to the invention differs from the preceding examples by a different distribution of the thickness of the functional metal layers: the second functional metal layer is the thinnest, the first functional metal layer is thicker than the second and the third functional metal layer is thicker than the first.

[0243] For these examples 21 and 24, the relatively large thickness of the layers of absorbent material in the second and third dielectric coatings compared to the relatively thin thickness of the layers of absorbent material in the first and fourth dielectric coatings makes it possible to attain the preferred optical characteristics for the invention (recalled in the second column) and even the more preferred values (in the 3.sup.rd column).

[0244] Examples 22 and 23 have the same distribution for the thickness of the functional metal layers as example 21 but do not attain the preferred optical characteristics for the invention since the thickness of the layers of absorbent material in the first and fourth dielectric coatings is too high compared to the thickness of the layers of absorbent material in the second and third dielectric coatings.

[0245] Likewise, examples 25 and 26 have the same distribution for the thickness of the functional metal layers as example 24 but do not attain the preferred optical characteristics for the invention since the thickness of the layers of absorbent material in the first and fourth dielectric coatings is too high compared to the thickness of the layers of absorbent material in the second and third dielectric coatings.