Substrate provided with a stack having thermal properties

Abstract

A transparent substrate includes a stack of thin layers successively including, starting from the substrate, an alternation of three metallic functional layers, in particular of functional layers based on silver or on silver-comprising metal alloy, and of four antireflective coatings, each antireflective coating including at least one dielectric layer, so that each metallic functional layer is positioned between two antireflective coatings, wherein: the thicknesses of the metallic functional layers, starting from the substrate, increase as a function of the distance from the substrate, the second metallic functional layer is directly in contact with a blocking layer, referred to as second blocking layer, chosen from a blocking underlayer and a blocking overlayer, respectively referred to as second blocking underlayer and second blocking overlayer, the second blocking underlayer and/or the second blocking overlayer exhibits a thickness of greater than 1 nm.

Claims

1. A transparent substrate comprising a stack of thin layers successively comprising, starting from the substrate, an alternation of three metallic functional layers, and of four antireflective coatings, each antireflective coating comprising at least one dielectric layer, so that each metallic functional layer is positioned between two antireflective coatings, the three metallic functional layers including starting from the substrate a first metallic functional layer, a second metallic functional layer and a third metallic functional layer, wherein: the thicknesses of the metallic functional layers, starting from the substrate, increase as a function of the distance from the substrate, and wherein, the second metallic functional layer is directly in contact with at least one second blocking layer, chosen from a second blocking underlayer and a second blocking overlayer, the second blocking underlayer and/or the second blocking overlayer exhibits a thickness of greater than 1 nm, said stack including the at least second blocking layer being devoid of a blocking layer directly in contact with the first and/or the third metallic functional layer, and the at least one second blocking layer is chosen from metallic layers based on a metal or on a metal alloy, metal nitride layers and metal oxynitride layers, or wherein, the second metallic functional layer is directly in contact with the at least one second blocking layer, chosen from the second blocking underlayer and the second blocking overlayer, the second blocking underlayer and/or the second blocking overlayer exhibits a thickness of greater than 1 nm, and the stack further comprises at least one blocking layer chosen from a first blocking layer located in contact with the first metallic functional layer and a third blocking layer located in contact with the third metallic functional layer, the first, second and/or third blocking layers respectively exhibit thicknesses CB1, CB2, CB3 satisfying the following equation: CB1+CB3<1.1 CB2, with at least the thickness CB2 nonzero, wherein the first, second and third blocking layers are chosen from metallic layers based on a metal or on a metal alloy, metal nitride layers and metal oxynitride layers.

2. The substrate as claimed in claim 1, wherein each metallic functional layer is in contact with at least one blocking layer.

3. The substrate as claimed in claim 1, wherein each metallic functional layer is in contact with a blocking overlayer.

4. The substrate as claimed in claim 1, wherein the first, the second and the third blocking layer satisfy the following characteristics: a ratio of the thickness of the second blocking layer CB2 to the thickness of the first blocking layer CB1 is greater than 1.10, a ratio of the thickness of the second blocking layer CB2 to the thickness of the third blocking layer CB3 is greater than 1.10.

5. The substrate as claimed in claim 4, wherein the ratio of the thickness of the second blocking layer CB2 to the thickness of the first blocking layer CB1 is from 1.10 to 10, and the ratio of the thickness of the second blocking layer CB2 to the thickness of the third blocking layer CB3 is from 2.00 to 10.

6. The substrate as claimed in claim 5, wherein the ratio of the thickness of the second blocking layer CB2 to the thickness of the first blocking layer CB1 is from 1.10 to 2, and the ratio of the thickness of the second blocking layer CB2 to the thickness of the third blocking layer CB3 is from 2.90 to 3.2.

7. The substrate as claimed in claim 1, wherein the first, second and third blocking layers are chosen from Ti, TiN, Nb, NbN, Ni, NiN, Cr, CrN, NiCr or NiCrN layers.

8. The substrate as claimed in claim 1, wherein the thickness of the second blocking layer CB2 is of from 1.5 to 3.5 nm.

9. The substrate as claimed in claim 1, wherein a total thickness of the first, second and third blocking layers is from 3 to 7 nm.

10. The substrate as claimed in claim 9, wherein the total thickness of the first, second and third blocking layers is from 3.5 to 5 nm.

11. The substrate as claimed in claim 1, wherein the first, the second and the third metallic functional layer satisfy the following characteristics: a ratio of the thickness of the second metallic layer to the thickness of the first metallic functional layer is from 1.50 to 2.20, a ratio of the thickness of the third metallic layer to the thickness of the second metallic functional layer is from 1.10 to 1.60.

12. The substrate as claimed in claim 11, wherein the ratio of the thickness of the second metallic layer to the thickness of the first metallic functional layer is from 1.80 to 2.20, and the ratio of the thickness of the third metallic layer to the thickness of the second metallic functional layer is from 1.10 to 1.55.

13. The substrate as claimed in claim 1, wherein the antireflective coatings corresponding to a first, to a second and to a third antireflective coating defined starting from the substrate exhibit a ratio of a thickness of a coating to the thickness of the preceding one which is from 0.90 to 1.20.

14. The substrate as claimed in claim 1, wherein the antireflective coatings comprise at least one dielectric layer based on oxide or on nitride of one or more elements chosen from silicon, aluminum, tin or zinc.

15. The substrate as claimed in claim 1, wherein each of the antireflective coatings comprises at least one dielectric layer having a barrier function based on silicon compounds chosen from silicon oxides SiO.sub.2, silicon nitrides Si.sub.3N.sub.4 and oxynitrides SiO.sub.xN.sub.y, optionally doped using at least one other element.

16. The substrate as claimed in claim 1, wherein each of the antireflective coatings comprises at least one dielectric layer having a stabilizing function based on zinc oxide; optionally doped using at least one other element.

17. The substrate as claimed in claim 1, comprising a stack, defined starting from the transparent substrate, comprising: a first antireflective coating comprising at least one dielectric layer having a barrier function and at least one dielectric layer having a stabilizing function, a first functional layer, a first blocking layer, a second antireflective coating comprising at least one lower dielectric layer having a stabilizing function, a dielectric layer having a barrier function and at least one upper dielectric layer having a stabilizing function, a second functional layer, a second blocking layer, a third antireflective coating comprising at least one lower dielectric layer having a stabilizing function, a dielectric layer having a barrier function and at least one upper dielectric layer having a stabilizing function, a third functional layer, a third blocking layer, a fourth antireflective coating comprising at least one dielectric layer having a stabilizing function and at least one dielectric layer having a barrier function.

18. A glazing comprising a transparent substrate as claimed in claim 1, wherein the glazing is in the form of a laminated glazing, of an asymmetrical glazing or of a multiple glazing of the double glazing type.

19. The substrate as claimed in claim 1, wherein the metallic layers, the metal nitride layers and the metal oxynitride layers include one or more elements chosen from titanium, nickel, chromium and niobium.

Description

(1) The advantageous characteristics and details of the invention emerge from the following nonlimiting examples, illustrated using the appended figures:

(2) FIG. 1 illustrates an example of the structure of a stack having three metallic functional layers according to the invention,

(3) FIG. 2 illustrates the colorimetric change as a function of the variation in the thickness of the blocking overlayers in transmittance (2.a), in external reflection (2.b) and in internal reflection (2.c),

(4) FIG. 3 illustrates the colorimetric change as a function of the variation in the thickness of the blocking underlayers in transmittance (3.a), in external reflection (3.b) and in internal reflection (3.c).

(5) The proportions between the various components are not observed in order to make the figures easier to read.

(6) FIG. 1 illustrates a stack structure having three metallic functional layers 40, 80, 120, this structure being deposited on a transparent glass substrate 10. Each functional layer 40, 80, 120 is positioned between two antireflective coatings 20, 60, 100, 140 so that: the first functional layer 40 starting from the substrate is positioned between the antireflective coatings 20, 60, the second functional layer 80 is positioned between the antireflective coatings 60, 100 and the third functional layer 120 is positioned between the antireflective coatings 100, 140.

(7) These antireflective coatings 20, 60, 100, 140 each comprise at least one dielectric antireflective layer 24, 28; 62, 64, 68; 102, 104, 106, 108; 142, 144.

(8) Each functional layer 40, 80, 120 can be deposited on a blocking or underblocking coating positioned between the antireflective coating underlying the functional layer and the functional layer.

(9) Each functional layer 40, 80, 120, 160 can be deposited directly under a blocking or overblocking coating 50, 90, 130 positioned between the functional layer and the antireflective coating overlying this layer.

EXAMPLES

(10) I. Preparation of the Substrates: Stacks, Deposition Conditions and Heat Treatments

(11) Stacks, defined below, of thin layers are deposited on substrates made of clear soda-lime glass with a thickness of 6 mm, distributed by Saint-Gobain.

(12) For these examples, the conditions for deposition of the layers, which were deposited by sputtering (“magnetron cathode” sputtering), are summarized in table 1.

(13) TABLE-US-00001 TABLE 1 Target Deposition Index employed pressure Gas 550 nm Si.sub.3N.sub.4 Si:Al at 92.8% 3.2 × 10.sup.−3 mbar Ar/(Ar + N.sub.2) 2.03 by weight at 55% ZnO Zn:Al at 98.2% 1.8 × 10.sup.−3 mbar Ar/(Ar + O.sub.2) 1.95 by weight at 63% SnZnO Sn (15% at.):Zn 3-5 × 10.sup.−3 mbar Ar/(Ar + O.sub.2) 2.03 (85% at.) at 75% NiCr Ni (80% at.):Cr 2-3 × 10.sup.−3 mbar Ar at 100% — (20% at.) Ag Ag 3 × 10.sup.−3 mbar Ar at 100% — at. = atomic

(14) Table 2 lists the materials and the physical thicknesses in nanometers (unless otherwise indicated) for each layer or coating making up the stacks as a function of their positions with respect to the substrate carrying the stack (final line at the bottom of the table). The “Ref.” numbers correspond to the references of FIG. 1.

(15) The substrates C.1, C.2, C.3, C.4 and Inv.AT were subjected to a heat tempering under the following conditions: heat treatment for 5 to 10 minutes at a temperature of between 600 and 750° C.

(16) The substrate Inv.BT was not subjected to a heat treatment.

(17) TABLE-US-00002 TABLE 2 Inv. Inv. Ref. C. 1 C. 2 C. 3 C. 4 AT BT Antireflective 140 26 26 31 28 26 24 coating AR4 Si.sub.3N.sub.4 144 20 20 25 22 20 18 ZnO 142 6 6 6 6 6 6 NiCr blocking 130 0.2 0.6 1 0.9 0.8 0.4 layer OB3 Functional 120 22.3 19.7 20.3 19.5 20.7 22 layer Ag3 Antireflective 100 62 61 67 75 62 61 coating AR3 ZnO 108 6 6 6 6 6 6 SnZnO 106 15 15 15 15 15 15 Si.sub.3N.sub.4 104 35 34 40 48 35 34 ZnO 102 6 6 6 6 6 6 NiCr blocking 90 0.3 0.4 0.4 0.8 2.5 2.8 layer OB2 Functional 80 17.1 18.1 18.3 17.6 16.3 14.8 layer Ag2 Antireflective 60 62 61 65 60 63 59 coating AR2 ZnO 68 6 6 6 6 6 6 Si.sub.3N.sub.4 64 50 49 53 48 51 47 ZnO 62 6 6 6 6 6 6 NiCr blocking 50 0.2 1.2 1.4 2 1.6 0.4 layer OB1 Functional 40 11.5 10.5 8.5 8 8.5 9.6 layer Ag1 Antireflective 20 30 36 50 52 56 32 coating AR1 ZnO 28 6 6 6 6 6 6 Si.sub.3N.sub.4 24 24 30 44 46 50 26 Glass 10 6 6 6 6 6 6 substrate (mm)

(18) Each antireflective coating 20, 60, 100 underlying a functional layer 40, 80, 120 comprises a final stabilizing layer 28, 68, 108 based on crystalline zinc oxide which is in contact with the functional layer 40, 80, 120 deposited immediately above.

(19) Each antireflective coating 20, 60, 100, 140 comprises a dielectric layer having a barrier function 24, 64, 104, 144 based on silicon nitride doped with aluminum, referred to here as Si.sub.3N.sub.4 for reasons of simplicity, although the true nature of the layer is in fact Si.sub.3N.sub.4:Al, as explained above.

(20) These layers based on silicon nitride are important in order to obtain the barrier effect to oxygen.

(21) The following table 3 summarizes the characteristics related to the thicknesses of the functional layers, of the antireflective coatings and of the blocking layers.

(22) TABLE-US-00003 TABLE 3 Inv. Inv. C. 1 C. 2 C. 3 C. 4 1AT 1BT Ratio thicknesses functional layers Ag2/Ag1 1.49 1.72 2.15 2.20 1.92 1.54 Ag3/Ag2 1.30 1.09 1.11 1.11 1.27 1.49 Ag3/Ag1 1.94 1.88 2.39 2.44 2.44 2.29 Σ thicknesses of the functional layers (Ag1 + Ag2 + Ag3) 50.90 48.30 47.10 45.10 45.5 46.4 Ratio thicknesses antireflective coatings AR2/AR1 2.07 1.69 1.30 1.15 1.13 1.84 AR3/AR2 1.00 1.00 1.03 1.25 0.98 1.03 AR4/AR3 0.42 0.43 0.46 0.37 0.42 0.39 Ratio thicknesses blocking layers OB2/OB1 1.50 0.33 0.29 0.40 1.56 7.00 OB2/OB3 1.50 0.67 0.40 0.89 3.13 7.00 OB1/OB3 1.00 2.00 1.40 2.22 2.00 1.00 Σ thicknesses OB1 + 0.70 2.20 2.80 3.70 4.90 3.60 OB2 + OB3 A = OB1 + OB3 0.40 1.80 2.40 2.90 2.40 0.80 B = 1.10 * OB2 0.33 0.44 0.44 0.88 2.75 3.08 A < B No No No No Yes Yes
II. “Solar Control” and Colorimetry Performances

(23) Table 4 lists the main optical characteristics measured for the substrates incorporated in a double glazing having the structure: 6-mm glass/16-mm inserted space filled with 90% argon/4-mm glass, the stack being positioned on face 2 (face 1 of the glazing being the outermost face of the glazing, as normal).

(24) For these double glazings: LT indicates: the light transmittance in the visible region in %, measured according to the illuminant D65 at 10° Observer; a*T and b*T indicate the a* and b* colors in transmittance in the LAB system measured according to the illuminant D65 at 10° Observer and measured perpendicularly to the glazing; LRext indicates: the light reflection in the visible region in %, measured according to the illuminant D65 at 10° Observer on the side of the outermost face, face 1; a*Rext and b*Rext indicate the a* and b* colors in reflection in the LAB system measured according to the illuminant D65 at 10° Observer on the side of the outermost face and thus measured perpendicularly to the glazing; LRint indicates: the light reflection in the visible region in %, measured according to the illuminant D65 at 10° Observer on the side of the innermost face, face 4; a*Rint and b*Rint indicate the a* and b* colors in reflection in the LAB system measured according to the illuminant D65 at 10° Observer on the side of the innermost face and thus measured perpendicularly to the glazing.

(25) TABLE-US-00004 TABLE 4 Inv. Inv. C. 1 C. 2 C. 3 C. 4 1AT 1BT Energy factors g 23.00 22.80 22.90 22.60 22.70 22.30 s 2.18 2.16 2.21 2.20 2.22 2.22 Color in transmittance LT % 50.2 49.2 50.6 49.7 50.5 49.7 a*T −4.2 −4.8 −5.6 −5.4 −8.4 −7.2 b*T 4.1 −0.3 1.9 2.4 0.2 0.6 Color in reflection LRext % 23.7 19.6 17.8 17.1 17.1 18.1 a*Rext −5.1 −4.2 −6.5 −5.8 −6.3 −6.5 b*Rext −9.4 −7.4 −8.6 −9.6 −8.9 −8.6 LRint % 30.5 26.3 23.7 23.2 20.3 20.6 a*Rint −10.3 −17.4 −19.7 −17.1 −7.7 −7.1 b*Rint −2.5 −1.7 −3.7 −3.6 −7.1 −7.1

(26) According to the invention, it is possible to produce a glazing comprising a stack having three metallic functional layers which exhibits a low light reflection, a highly advantageous selectivity (LT/g ratio) of the order of 2.2, and also an excellent compromise for the colors in internal and external reflection and in transmittance, insofar as all the a* and b* values are between −9 and 1.

(27) The advantageous properties relating to the internal reflection make it possible, when it is dark outside illuminated premises equipped with glazings of the invention, to see these colored glazings in a pleasant manner and to prevent mirror effects.

(28) The glazings according to the invention thus offer good solar protection within a range of light transmittances which is particularly suitable for equipping buildings experiencing high exposure to sunlight.

(29) The combination of the increasing metallic functional layers and the use of one or more thick blocking layers around the second metallic functional layer contribute to these better results being obtained: low light reflection and lower solar factor, in order to be able to obtain a high selectivity with a color in reflection, both from the outside and from the inside, which is neutral, in the blue-green range.

(30) III. Influence of the Presence and of the Thickness of the Blocking Layers Concentrated Around the Second Functional Layer

(31) FIGS. 2.a, 2.b and 2.c illustrate the trend of the colorimetric change according to the variation in the thickness of the blocking overlayers respectively in transmittance, in external reflection and in internal reflection.

(32) FIGS. 3.a, 3.b and 3.c illustrate the trend of the colorimetric change according to the variation in the thickness of the blocking underlayers respectively in transmittance, in external reflection and in internal reflection.

(33) The arrows represent the direction of the increasing increase in the thicknesses of the blocking overlayers and underlayers.

(34) Starting from a reference substrate comprising three blocking overlayers (OB1, OB2, OB3) respectively located above each of the three functional layers, the following were varied: the thickness OB1 of the first blocking overlayer located above the first functional layer (keeping unchanged all the other thicknesses of the stack, including OB2 and OB3), the thickness OB2 of the second blocking overlayer located above the second functional layer (keeping unchanged all the other thicknesses of the stack, including OB1 and OB3), the thickness OB3 of the third blocking layer located above the third functional layer (keeping unchanged all the other thicknesses of the stack, including OB1 and OB2).

(35) Starting from a reference substrate comprising three blocking underlayers (UK, UB2, UB3) respectively located below each of the three functional layers, the following were varied: the thickness UB1 of the first blocking underlayer located above the first functional layer (keeping unchanged all the other thicknesses of the stack, including UB2 and UB3), the thickness UB2 of the second blocking underlayer located above the second functional layer (keeping unchanged all the other thicknesses of the stack, including UB1 and UB3), the thickness UB3 of the third blocking underlayer located above the third functional layer (keeping unchanged all the other thicknesses of the stack, including UB1 and UB2).

(36) The comparative examples C.1 to C.4 exhibit a* values in internal reflection which are too low and in particular less than −10 (see table 4).

(37) In point of fact, the analysis of the colorimetric curves and more particularly of the curves 2.c and 3.c shows that only the increase in thickness of the second blocking layer located above or above the second functional layer makes it possible to increase the a* values.

(38) Consequently, the concentration of the blocking layers in contact with the second functional layer makes it possible to obtain internal reflection properties which are advantageous in terms of colorimetry.

(39) Furthermore, surprisingly, a lower internal light reflection LR is also obtained.

(40) Finally, satisfactory colors in internal reflection are obtained without harming the color in transmittance and in external reflection, which is entirely unforeseeable. Specifically, the a* and b* values are all of between −9 and 1.

(41) In point of fact, FIGS. 2.a, 2.b and 3.a, 3.b, which illustrate the trend of the colorimetric change according to the variation in the thickness of the blocking underlayers and overlayers in transmittance and in external reflection, give absolutely no suggestion of the excellent compromise obtained according to the invention in terms of color in transmittance, in internal reflection and in external reflection, of light reflection and of solar control performance.