GLAZING COMPRISING A FUNCTIONAL COATING

Abstract

A material includes a transparent substrate coated with a stack of thin layers including at least one functional coating including at least one silver-based metal functional layer, and at least one niobium-based metal or nitride functional layer.

Claims

1. A material comprising a transparent substrate coated with a stack of thin layers comprising at least one functional coating comprising: at least one silver-based metal functional layer exhibiting a thickness of between 2 and 15 nm, optionally at least one blocking layer chosen from metal layers, metal nitride layers, metal oxide layers and metal oxynitride layers of one or more elements chosen from titanium, nickel, chromium and tantalum, one or more niobium-based metal or nitride functional layers located: in contact with at least a portion of the silver-based functional layer or separated from at least a portion of the silver-based functional layer by one or more blocking layers, a sum of thicknesses of the one or more blocking layers is less than 5 nm, a sum of thicknesses of the one or more niobium-based functional layers, located directly in contact with or separated by a thickness of less than 5 nm from at least a portion of the silver-based functional layer, is between 4 and 20 nm.

2. The material as claimed in claim 1, wherein the functional coating comprises at least one niobium-based functional layer located above at least a portion of the silver-based functional layer and exhibiting a thickness of between 2 and 10 nm.

3. The material as claimed in claim 1, wherein the functional coating comprises at least one niobium layer located below at least a portion of the silver-based functional layer and exhibiting a thickness of between 1 and 10 nm.

4. The material as claimed in claim 1, wherein the functional coating comprises a blocking layer located below and/or above a silver-based metal functional layer.

5. The material as claimed in claim 1, wherein the thickness of one of the one or more blocking layers is at least 0.2 nm and at most 5.0 nm.

6. The material as claimed in claim 1, wherein the functional coating exhibits a thickness of between 5 and 20 nm.

7. The material as claimed in claim 1, wherein the stack of thin layers comprises at least one functional coating and at least two dielectric coatings comprising at least one dielectric layer, so that each functional coating is positioned between two dielectric coatings.

8. The material as claimed in claim 1, wherein the stack of thin layers comprises only one functional coating.

9. The material as claimed in claim 1, wherein the stack of thin layers comprises at least one dielectric coating comprising at least one dielectric layer consisting of a nitride or of an oxynitride of aluminum and/or of silicon or of a mixed zinc tin oxide.

10. The material as claimed in claim 1, wherein the stack of thin layers comprises at least one dielectric coating located below the functional coating, the at least one dielectric coating comprising only one layer consisting of a nitride or of an oxynitride of aluminum and/or of silicon, with a thickness of between 30 and 70 nm.

11. The material as claimed in claim 1, wherein the stack of thin layers comprises at least one dielectric coating located above the functional coating, the at least one dielectric coating comprising: at least one layer consisting of a nitride or of an oxynitride of aluminum and/or of silicon, with a thickness of between 30 and 60 nm, optionally at least one protective layer with a thickness of between 2 and 10 nm.

12. The material as claimed in claim 1, wherein the transparent substrate is: made of glass, or made of polymer.

13. A process for the preparation of a material comprising a transparent substrate coated with a stack of thin layers deposited by cathode sputtering, optionally magnetic-field-assisted cathode sputtering, the process comprising the sequence of following stages: depositing on the transparent substrate at least one functional coating comprising at least one silver-based functional layer exhibiting a thickness of between 2 and 10 nm and at least one niobium-based functional layer exhibiting a thickness of between 2 and 10 nm, located below and/or above and in contact with at least a portion of the silver-based functional layer; depositing a coating based on dielectric materials is deposited above the functional layer, subjecting the substrate thus coated is to a heat treatment.

14. A glazing comprising at least one material as claimed in claim 1.

15. The glazing as claimed in claim 14, wherein the glazing is in the form of a monolithic, laminated or multiple glazing.

16. The material as claimed in claim 1, wherein the optional at least one blocking layer is selected from the group consisting of Ti, TiN, TiO.sub.x, Ta, TaN, Ni, NiN, Cr, CrN, NiCr or NiCrN.

17. The material as claimed in claim 1, wherein each silver-based metal layer is positioned in contact and between the one or more niobium-based metal or nitride functional layers and/or the one or more blocking layers.

18. The material as claimed in claim 9, wherein a thickness of the at least one dielectric layer is between 20 and 70 nm.

19. The material as claimed in claim 10, wherein the layer consisting of a nitride or of an oxynitride of aluminum and/or of silicon is a layer consisting of silicon nitride, optionally additionally comprising aluminum.

20. The material as claimed in claim 11, wherein the layer consisting of a nitride or of an oxynitride of aluminum and/or of silicon is a layer consisting of silicon nitride, optionally additionally comprising aluminum.

21. The material as claimed in claim 12, wherein the glass is soda-lime-silica glass, and the polymer is polyethylene, polyethylene terephthalate or polyethylene naphthalate.

Description

EXAMPLES

[0165] Stacks of thin layers defined below are deposited on substrates made of clear soda-lime glass.

[0166] The stacks are deposited, in a known way, on a cathode sputtering line (magnetron process) in which the substrate progresses forward under different targets.

[0167] For these examples, the conditions for deposition of the layers deposited by sputtering (magnetron cathode sputtering) are summarized in the table below.

TABLE-US-00001 TABLE 1 Targets Deposition In- employed pressure Gas dex* Si.sub.3N.sub.4 Si:Al (92:8% by wt) 2-10*10.sup.3 mbar Ar: 30-80% - N.sub.2: 2.00 20-70% NiCr Ni:Cr (80:20 at. %) 1-5*10.sup.3 mbar 100% Ar Ag Ag 2-3*10.sup.3 mbar 100% Ar Nb Nb 5-10*10.sup.3 mbar 100% Ar TiO.sub.2 TiO.sub.x 1.5*10.sup.3 mbar 88% Ar - 12% O.sub.2 2.32 at.: atomic; wt: weight; *at 550 nm.

[0168] Table 2 lists the materials and the physical thicknesses in nm of each layer or coating which forms the stacks of MA and MB type as a function of their position with regard to the substrate carrying the stack (final line at the bottom of the table). The thicknesses given correspond to the thicknesses before tempering.

TABLE-US-00002 TABLE 2 MA MB Dielectric coating TiO.sub.x 9 nm 9 nm Si.sub.3N.sub.4 37 nm 37 nm Functional coating cf. Tab. 3 cf. Tab. 3 Dielectric coating Si.sub.3N.sub.4 55 nm 55 nm Substrate: Glass 4 mm 4 mm

[0169] The materials of examples MA1 to MA3 and MB1 to MB4 respectively comprise the stacks of MA and MB type are two different series of tests. The stacks of these series which differ in the nature of the functional coating. The functional coatings comprise a sequence of the several layers defined in table 3. The first layer mentioned corresponds to the layer of the functional coating closest to the substrate. The thicknesses given in this table are physical thicknesses in nanometers.

TABLE-US-00003 TABLE 3 Tot. Thick. Functional coating (nm) Ag Nb FC Nb/Ag MA1 Nb (2.3)/Ag (6)/Nb (4.2) 6 6.5 12.5 1.08 MA2 Nb (2.3)/Ag (5)/Nb (4.5) 5 6.8 11.8 1.36 MA3 Nb (2.3)/Ag (4.5)/Nb (4.7) 4.5 7 11.5 1.56 MB1 Nb (2.3)/Ag (5)/Nb (4.5) 5 6.8 11.8 1.36 MB2 Nb (1.5)/NiCr (0.7)/Ag (5)/NiCr 5 5.3 11.7 1.06 (0.7)/Nb (3.8) MB3 Nb (1.4)/NiCr (0.9)/Ag (5)/NiCr 5 5 11.8 1 (0.9)/Nb (3.6) MB4 NiCr (2.3)/Ag (5)/NiCr (4.5) 5 0 11.8 0

I. Solar Control and Colorimetry Performance Qualities

[0170] The main optical characteristics measured when the materials MA1 to MA3 are fitted in a single glazing, the stack being positioned on face 2, the face 1 of the glazing being the outermost face of the glazing, as usual, are listed in table 4.

[0171] For these glazings: [0172] LT indicates the light transmission in the visible region in %, measured according to the illuminant D65 at 2 Observer; [0173] LRe 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, the face 1; [0174] a*Re and b*Re indicate the colors 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 measured thus perpendicularly to the glazing; [0175] LRi 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, the face 2; [0176] a*Ri and b*Ri indicate the colors 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 measured thus perpendicularly to the glazing; [0177] Abs. indicates the absorbance in the visible region in % corresponds to (100LT %LRi %) measured according to the illuminant D65 at 2 Observer.

[0178] These characteristics are measured for the glazing provided with the stack first at the outlet of the magnetron line and then after a heat treatment of tempering type consisting in particular of an annealing at 650 C. for 10 minutes.

[0179] The relative variations in each characteristic attributable to the heat treatment are also specified in table 4. For example, the variation in the light transmission was calculated in the following way: LT=(LT % after HTLT % before HT)/(LT % before HT)100 with HT meaning heat treatment.

TABLE-US-00004 TABLE 4 Int. reflection Ext. reflection HT LRi a * Ri b * Ri LRe a * Re b * Re Abs. LT LT LRi LRe Abs MA1 Before 3.8 26.1 19.4 15.2 2.3 16.4 43.3 53.0 4 5 8 1 After 4 24.7 14.4 16.4 1.7 13.9 43.9 50.8 MA2 Before 3.9 26 16.9 15.4 2.3 15.8 43.3 52.8 3 5 8 4 After 4.1 24.9 13.1 16.7 1.7 12.7 44.9 51.0 MA3 Before 4.8 22.1 5.7 15 2.8 15.1 43.3 51.9 2 4 7 1 After 5 20.3 1 16 2.1 11.8 43.9 51.1

[0180] Table 5 is concerned with the performance qualities of the materials and shows the relative variations in emissivity attributable to the heat treatment. The variation in emissivity was calculated in the following way: =( after HT before HT)/( before HT)100.

TABLE-US-00005 TABLE 5 Performance qualities HT g s Ug MA1 Before 46.8 1.13 22.5 3.9 5 After 48.1 1.10 21.3 3.9 MA2 Before 47.4 1.11 28.5 4.1 1 After 46.7 1.09 28.1 4.1 MA3 Before 47.2 1.10 32.2 4.3 0 After 47.4 1.08 32.3 4.3 g: solar factor in %; s: selectivity; : emissivity in %; Ug: heat transfer coefficient.

[0181] According to the invention, the functional coating according to the invention makes it possible to obtain a relatively high value for the light transmission of the substrate, while retaining a significant insulating effect, despite the very low thickness of the silver-based metal functional layer, after a heat treatment.

[0182] The examples show that the materials according to the invention exhibit a very good compromise between the light transmission LT, the solar factor and the emissivity. It is clearly apparent that its very good initial properties are completely undamaged when the glazing is subjected to the heat treatment.

[0183] The solution of the invention makes it possible to obtain a stability of the characteristics of the glazing before and after the heat treatment. The materials thus exhibit a noteworthy stability of the optical and colorimetric characteristics before and after the heat treatment.

[0184] The materials according to the invention exhibit in particular an emissivity coefficient which is sufficiently low, in particular of less than 35%, indeed even of less than 25%. Furthermore, after the heat treatment, the materials according to invention exhibit an emissivity which is preferably substantially improved or at the very least substantially unchanged.

II. Tests of Resistance to Aging and to Abrasion

[0185] Tests according to the standard EN 1096 for evaluating the resistance of the stack of thin layers to weathering and to abrasion were carried out and in particular: [0186] the test of resistance to acid attacks (Annex C of the standard), known as SO.sub.2 test, [0187] the test of resistance to neutral salt spray (Annex D of the standard), known as NSS test, [0188] the test of resistance to neutral condensation (Annex B of the standard), known as high humidity (HH) test, [0189] the test of resistance to abrasion, also known as Taber test.

[0190] An Erichsen brush test was also carried out.

[0191] An analysis by optical microscopy after some tests was carried out. It makes it possible to demonstrate the presence of defects. The following assessments were reported after microscopic observation:

: presence of many pits,
0: presence of a few pits,
+: virtually no pits.

[0192] The following devices were used: [0193] Minolta No. ISO 1325, [0194] SO.sub.2 chamber No. ISO 1038, [0195] Perkin-Elmer No. ISO 1043, Mirror W1 No. 1066, [0196] Neutral salt spray (NSS) chamber No. ISO 981, [0197] High humidity (HH) chamber, [0198] Light booth No. ISO 732, [0199] Microscope No. ISO 185.

[0200] The size of the samples is 1010 cm. Unless otherwise indicated, the measurements were carried out after heat treatment as defined above.

II.1. TESTS ON THE MATERIALS OF MA TYPE

[0201] a. SO.sub.2 Test

TABLE-US-00006 TABLE 6 E layer Cycles BT AT BT AT MA1 0 23.67 22.73 15 0.33 1.77 24.10 22.86 25 3.49 2.67 24.64 22.71 MA3 0 33.01 33.82 15 0.69 0.24 33.34 33.83 25 3.21 1.09 33.41 33.77 45 1.87 0.94 33.51 33.91 BT: Before HT, AT: After HT.

TABLE-US-00007 TABLE 7 Light booth Optical microscope Cycles BT AT BT AT MA1 25 NOK OK + MA3 25 OK OK + + 45 OK OK + +
The materials MA1 after heat treatment and MA3 before and after heat treatment are satisfactory. The example MA1 before heat treatment (BT) is not satisfactory after 25 cycles. The emissivity increases, the visual appearance in the light booth and the photographs with the optical microscope are not acceptable.
b. High Humidity (HH) Test

[0202] In order to evaluate the chemical resistance of the stack, an accelerated aging test, referred to as test of resistance to high humidity, was carried out. This test consists in placing a material in a drying oven heated at 120 C. for 480 minutes exhibiting a relative humidity of 100%. The visual observation of the material according to the invention after heat treatment makes it possible to note the absence of haze. The materials MA1 after heat treatment and MA3 before and after heat treatment are not damaged after having been subjected to the HH test for 56 days. Only the material MA1 before heat treatment BT is damaged when it is observed in the light booth.

c. Test of Resistance to Neutral Salt Spray (NSS)

[0203] The materials MA1 to MA3 are not damaged after having been subjected to the NSS test for 56 days. MA1 before heat treatment BT is damaged when it is observed in the light booth. Only a few sites of corrosion are observed on MA1 after heat treatment.

d. Test of Resistance to Abrasion

[0204] The test of resistance to abrasion was carried out with a load of 500 g for 500 cycles. The LT and the Haze are given in %.

TABLE-US-00008 TABLE 8 Initial 500 cycles HT LT Haze LT Haze LT Haze MA3 Before 49.5 0.07 54.4 5.64 4.9 5.57 MA3 After 49.7 0.04 51 4.1 1.3 4.06

[0205] The material MA3 is satisfactory. The results are acceptable with variations in light transmission of less than 5% for the abrasion test before and after heat treatment.

e. Erichsen Brush Test (EBT)

[0206] The materials MA1 to MA3 were subjected to the Erichsen brush test (EBT), for 1000 cycles, before (EBT) and after tempering (HTEBT). This test consists in rubbing the stack using a brush having hairs made of polymer material, the stack been covered with water. A glazing is regarded as satisfying the test if no mark is visible to the naked eye. The materials MA1 to MA3 satisfy the test before and after heat treatment.

II.2. TESTS ON MATERIALS OF MB TYPE

[0207]

TABLE-US-00009 TABLE 9 SO.sub.2 Ei Ee MB1 initial 4.19 0.31 26.7 35 cy. 26.7 MB2 initial 0.91 0.11 26.7 35 cy. 26.8 MB3 initial 1.04 0.11 26.9 35 cy. 26.9 MB4 initial 15.68 3.86 25.7 15 cy. 35.6
a. SO.sub.2 Test

TABLE-US-00010 TABLE 10 SO.sub.2 Light booth Microscope MB1 35 cy. OK 0 MB2 35 cy. OK 0 MB3 35 cy. OK 0 MB4 15 cy. NOK

[0208] The examples MB1 to MB3 are satisfactory, in contrast to the comparative example MB4, which is not satisfactory. The example MB4 does not comprise a niobium-comprising layer but only blocking layers. This is because the Ei of the example MB4 is much too high (>5). Furthermore, the emissivity has also excessively increased (more than 2 points).

b. NSS Test

TABLE-US-00011 TABLE 11 NSS (days) Ei Ee MB1 initial 0.87 0.19 26.3 42 26.3 MB2 initial 2.81 0.15 26.7 42 26.8 MB3 initial 1.66 0.23 26.8 42 27 MB4 initial 13.18 5.06 26.3 14 34.1

TABLE-US-00012 TABLE 12 Light booth Microscope MB1 Ok + MB2 Ok + MB3 Ok + MB4 NOk

[0209] The examples MB1 to MB3 are satisfactory, in contrast to the comparative example MB4, which is not satisfactory. This is because the E of the example MB4 is much too high (>5). Furthermore, the emissivity has also excessively increased (more than 2 points).

c. High Humidity (HH) Test

TABLE-US-00013 TABLE 10 HH (days) Ei Ee MB1 initial 1.29 0.10 26.3 42 26.3 MB2 initial 1.71 0.19 26 42 26 MB3 initial 3.30 0.09 26.9 42 26.4 MB4 initial 0.42 0.25 26.8 42 28.8

TABLE-US-00014 TABLE 11 Light booth Microscope MB1 OK + MB2 OK + MB3 OK + MB4 OK +

[0210] The examples MB1 to MB3 are satisfactory, in contrast to the comparative example MB4, which is not satisfactory. This is because the emissivity of the example MB4 has excessively increased (2 points).

d. Test of Resistance to Abrasion

TABLE-US-00015 TABLE 13 Resistance to abrasion after heat treatment Initial 500 cycles (500 cycles) LT Haze LT Haze LT Haze MB1 51.3 0.3 60.8 3.61 9.50 3.31 MB2 51.9 0.41 57.5 3.92 5.60 3.51 MB3 52.2 0.44 59.0 3.74 6.80 3.30 MB4 59.4 0.35 76.8 3.10 17.40 2.75

[0211] The examples MB2 and MB3 with a blocking layer exhibit the best results with in particular a much lower variation in light transmission.

II.3. CONCLUSION

[0212] The functional coatings comprising a silver layer bounded by two niobium-based layers with optionally one or more blocking layers are preferred.

[0213] The presence of a thin blocking layer above and/or below the silver layer gives good results in terms of abrasion resistance.

[0214] The best results are obtained when the thickness of the silver-based functional layers in a functional coating is, by increasing order of preference, less than 6 nm, from 3 to 6 nm, from 4 to 5.5 nm. For this, the results obtained with the materials MA1 and MA3 may be compared.