FR2708262A1 - Transparent solar protection glazing. - Google Patents

Abstract

The invention relates to a transparent solar protection glazing comprising a coating deposited on a substrate. The coating comprises: (i) a non-absorbent layer (14); (ii) a layer (16) of material whose spectral absorption index k (lambda) in the visible range is greater than the refractive index n (lambda) and, of which k (lambda), the length of wave (lambda) of 550 nm, is greater than 1.67 times n (lambda); (iii) a layer (18) of absorbent material of which k (lambda), in the visible range, is between 0.3 and 1.0 times n (lambda), and whose thickness is such that, if applied as a single layer on 6mm thick soda lime glass, the light transmittance TL is reduced by at least 30%; and (iv) a non-absorbent diaper (20). The glazing according to the invention provides effective solar protection while providing high light transmission and tint purity.

Description

Transparent solar protection glazing The present invention is

  relates to transparent windows of

sunscreen.

  Reflective and transparent solar protection glazing has become a useful product for architects on the exterior facades of buildings. Such glazings have aesthetic qualities of reflection of the immediate environment and, being available in several colors, they provide a design opportunity. Such glazings also have technical advantages in providing the occupants of a building protection against solar radiation by reflection and / or absorption and eliminating the annoying effects of intense sunlight, which provides effective protection against glare , improves visual comfort

and reduces eyestrain.

  From a technical point of view, it is desired that the glazing does not let too large a proportion of total incident solar radiation pass in order not to overheat the interior of the building during periods of sunshine. The transmission of total incident solar radiation can be expressed in terms of "solar factor". As used herein, the term "solar factor" means the sum of the total energy directly transmitted and the energy that is absorbed and re-radiated on the far side of the energy source, such as a proportion of the radiation. total incident energy on the coated glass. It is also desired that the glazing also transmits a reasonable proportion of visible light to allow a natural illumination of the building interior and to allow the occupants to see outside. The transmission of visible light can be expressed in terms of "transmittance" as a proportion of the incident light reaching the substrate carrying the coating. It is therefore desirable to increase the selectivity of the coating, that is to say to increase the ratio of the transmission factor on the solar factor. There are several documents that describe glazing with a coating providing protection against solar radiation. For example, US Pat. No. 4,902,081 (Viracon) discloses a low-emissivity, low-shading coefficient glazing with low reflection in which a

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  substrate is coated with a first layer of metal oxide, a second layer of silver, a third layer consisting of a metal such as titanium, a fourth layer of metal oxide and a fifth layer. outer layer of titanium nitride. It has been found that glazing constructed in accordance with the teaching of US 4,902,081 has a gray color of low purity when viewed in reflection. Although one skilled in the art may consider that the deposition of additional layers modifies the properties of known glazings, such

  approach would significantly increase the cost and difficulty of manufacturing.

  From an aesthetic point of view, it is preferred to improve the color purity of the glazings when viewed in reflection, in particular in such a way that the entire glazed facade of a building has a uniform appearance when viewed. from the outside. It has been found that the purity of color is particularly difficult to obtain simultaneously with a relatively high ratio of the factor of transmission on the solar factor,

  especially with blue glazing.

  Therefore, one of the objects of the present invention is to provide a glazing having a high transmittance, a low solar factor and a high purity of reflected color. Another of the other preferred objects of the present invention is to provide such a glazing unit which uses little components

  expensive and that can be manufactured in a simple way.

  The present invention relates to a transparent solar protection glazing characterized in that it comprises a substrate carrying a coating consisting of: (i) a first layer comprising a non-absorbent material; (ii) a second layer selected from materials for which the spectral absorption index k (x), for wavelengths (X) between 380 and 780 nm, is greater than the refractive index n (X) and, whose spectral absoption index k (X) at the wavelength (X) of 550 nm is greater than 1.67 times the refractive index n (X); (iii) a third layer comprising an absorbing material for which the spectral absorption index k (X) for wavelengths (X) of between 380 and 780 nm is between 0.3 and 1.0 times the refractive index n (X) of the material, said third layer having a thickness such that, when applied as a single layer to a 6 mm thick soda-lime glass substrate, its TL light transmission factor is reduced by at least 30%; and

  (iv) a fourth layer comprising a non-absorbent material.

  The glazing according to the invention makes it possible to obtain the objectives

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  Simultaneous high selectivity with high reflection color purity for low manufacturing cost and simple multilayer coating structure. Achieving high color purity is surprising because a layer of absorbent material applied to a multiple coating according to US 4,902,081 gives a gray color when viewed from the uncoated side of the substrate. The reason for this difference is not fully understood, but it seems possible that the benefit of the present invention derives from the interface between the absorbent material of the third layer and the material of the second layer. However, it has been found that the advantages of the invention are not obtained if the order of the second and third layers is inverted, from the same uncoated side, as well as if these layers are not surrounded by the first and fourth layers. of non-absorbent material. The substrate may be in the form of a film, such as a plastic film, but it is preferably in the form of a sheet of vitreous material, such as glass or other transparent rigid sheet material. It is particularly advantageous to use tempered or thermally hardened glass, although laminated glass can also be used. Given the proportion of incident solar radiation that is absorbed by the glazing, especially in environments where it is exposed to intense or long-lasting solar radiation, the glazing undergoes a heating that implies that the use of

  Untempered glass as a substrate should preferably be avoided.

  However, the high selectivity of the glazing according to the invention limits the energy absorption of the glazing for a given light transmission, which attenuates

the need to soak the glass.

  The different layers of the coated glazing act together in a beneficial manner to achieve the object of the invention. The precise properties obtained may vary according to the choice of materials constituting each

  layer and according to their thickness.

  By the term "non-absorbent material" used herein, there are materials which have a "refractive index" n (X) which is greater than, and preferably substantially greater than, the value of "the index of spectral absorption "k (X) over the entire visible spectrum (380 to 780 nm). Definitions of the refractive index and spectral absorption index can be found in the International Vocabulary of Illumination, published by

  International Commission on Illumination (CIE), 1987, pages 127, 138 and 139.

  In particular, it has been found advantageous to choose a material whose refractive index n (X) is greater than 10 times the spectral absorption index k (X) on the

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  range of wavelengths between 380 and 780 nm. The non-absorbent material of the first and fourth layers may be independently selected from zinc sulfide, silicon carbide, lithium, sodium and thorium fluorides, zinc selenide, silicon and aluminum nitrides, and the like. aluminum oxynitride, titanates of barium and strontium, oxides of aluminum, beryllium, bismuth, magnesium, silicon (SiO and SiO2), tin, titanium, yttrium and zinc , and their mixtures. The non-absorbent material of the first and fourth layers is preferably selected from Si3N4, AlN, ZnO, SnO2 and TiO2. The following table shows the refractive index n (X) and the spectral absorption index k (X,) of a number of

  suitable non-absorbent materials in the range of 380 to 780 nm.

Table I

  Material n (X) k (X) ZnO 2.3 - 2.02 0.08 - 0.001 Si3N4 2.08- 2.01 0 * SiO2 1.56 - 1.54 0 *

A1203 1.79 - 1.76 0 *

AION 1.81 - 1.78 0 *

MgO 1.77-1.73 0 *

Y203 1.98- 1.93 0 *

  SiC 2.78 - 2.6 0 * ZnS 2.4 - 2.3 0 * TiO2 2.64 - 2.31 0 * SnO2 1.94- 1.85 0 * BiO2 2.92 - 2.48 0.1 - 0 *

Note: 0 * means less than 10-3.

  It is particularly preferred that the material of the first and fourth layers be the same material, at least for ease of manufacture, and ideally this material is zinc oxide and / or stannic oxide, while the oxide is Titanium is advantageous if greater resistance to abrasion is required. These layers of non-absorbent materials act respectively as a base for the other layers of the coating and as a protection against the environment. It is usual for the layers of non-absorbent material to have a larger refractive index than that of the substrate. It should be noted that in the layers of non-absorbent material containing oxide or metal nitride, it is not essential that the metal and oxygen or nitrogen be

  present in stoichiometric proportions.

  The second layer is the layer initially responsible for the

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  selectivity of the coating. In particular, these materials have a spectral absorption index k (X) greater than the refractive index n (X) over the range of the visible spectrum, and at least 1.67 times greater at the wavelength. 550 nm. Such suitable materials include metals selected from aluminum, copper, gold, nickel, iridium, platinum, palladium, rhodium, zinc and silver, and mixtures thereof, particularly money. Lithium, sodium and potassium also have the necessary characteristics, but being reactive, they require to be used in doped form or in the form of alloy. The following table shows the refractive index n (X) and the spectral absorption index k (X) of a number of suitable materials in the range 380 nm / 550 nm / 780 nm.

Table II

Material n (X) k (X)

AI 0.36 / 0.76 / 1.9 3.78 / 5.32 / 7.12

  Neither 1.61 / 1.77 / 2.45 2.25 / 3.25 / 4.35 Pt 1.65 / 2.15 / 2.8 2.7 / 3.7 / 5 Ag 0.2 / 0.12 / 0.145 1.75 / 3.4 /5.2 Cu 1.18 / 0.9 / 0.25 2.21 / 2.6 / 5. 1 to 1.68 / 0.35 / 0.18 1.92 / 2.7 / 5.1 Pd 1.25 / 1.64 / 2 2.81 / 3.84 / 5 Zn 0.16 / 0.33 / 0. 2.9 / 4.4 /6.2 When a blue reflected color is required, it is preferred to use silver for the dual purpose of economy and ease of deposit. In the

  following description, this layer is referenced for simplicity as

layer of money.

  The absorbent material of the third layer is a material for which the spectral absorption index k (X) is between 0.3 and 1.0 times the refractive index of the material. In particular, the material of the third layer may be chosen from tungsten, stainless steel (SS) (containing for example at least 12% chromium), nitrides of titanium, chromium or aluminum / titanium alloys, "nitride" of stainless steel (SSN), and mixtures thereof. The following table shows the refractive index n (X) and the spectral absorption index k (X) of a number of suitable absorbing materials.

in the range 380 nm / 780 nm.

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Table III

Material n (X) k (X)

SS 3.46 - 4.2 2.32 - 4.06

TiN 2.62- 2.8 1.46- 2.1

SSN # 2.69 - 4 2.15 - 3.52

W 3.45 - 3.67 2.49 - 2.68

  Note: #SSN = stainless steel nitride obtained by cathode sputtering using a stainless steel cathode in a nitrogen atmosphere. Titanium nitride and "nitride" of stainless steel are particularly preferred. The nitride layer may also comprise elemental or oxidized metal and in particular the metal and nitrogen must not be present in stoichiometric proportions. The absorbent material forms an absorbent layer and its interface with the second layer is responsible for reducing the light transmittance of the coated glass vis-à-vis solar radiation. The layer of absorbent material also plays an important role in obtaining the desired color because of the advantageous effect deriving from its

  combination with the first, second and fourth layers.

  An intermediate layer comprising a sacrificial metal may be interposed between said second and third layers, said intermediate layer having a thickness of less than 10 nm. The sacrificial metal acts to protect the silver layer, in particular against the damage that may result from the coating of the silver layer by the layer of absorbent material that would lead to a loss of performance of the glazing. In addition, a thin layer of sacrificial metal may also be disposed between the first and second layers. The sacrificial metal is preferably selected from aluminum, bismuth, chromium, a chromium-nickel alloy, tin, titanium, zinc and mixtures thereof. Ideally, the nitride of the third layer comprises a nitride of the same metal as the sacrificial metal of the intermediate layer. The presence of an intermediate layer can modify the emissivity characteristics of the glazing without any noticeable change in the reflected color, since its thickness is relatively small. Advantageously, the thickness of the intermediate layer is not greater than 6 nm, preferably not greater than 3 nm. Whether the intermediate layer becomes totally transparent in the finished product, or that it remains totally or partially metallic, or that it is in the form of a nitride, it will preferably also be

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  as thin as possible so as not to alter the reflected color that the coating would have without an intermediate layer, unless it satisfies the conditions of the

  third layer, because in this case it is part of the third layer.

  A thin layer of sacrificial metal may also be disposed between said third and fourth layers to protect the absorbent layer from alteration that may result from the overlap of this layer

by the fourth layer.

  The thickness of the different layers deposited on the glazing is important for optimal performance. It is preferred that the optical thickness (measured in transmission) of the first layer be between 10 and 280 nm [the optical thickness is the product of the actual (i.e. geometric) thickness by the index of refraction]. Preferably, the optical thickness of the first layer is at least 100 nm, while the total optical thickness of the first and fourth layers (of non-absorbing material) is between 180 and 270 nm, with the optical thickness of the first layer greater than that of the fourth layer, for example 1.1 to 1.7 times larger. As a rule, a preferred optical thickness for the first layer (non-absorbent material) is 110 to 160 nm and that for the fourth layer (material

  non-absorbent) is 70 to 120 nm.

  The geometric thickness of the second layer is preferably

  between 3 and 18 nm, preferably between 5 and 15 nm.

  The geometric thickness of the third layer must be sufficient for the layer to act as an absorber in the finished product. It has been found that the third layer must be able, when applied as a single coating, to reduce the light transmittance of a soda-lime glass substrate 6 mm thick by at least 30 mm. %, i.e. TL is, for example, reduced from 90% to less than 60%. The thickness of the third layer is preferably such that, when applied as a single layer to a 6 mm thick soda-lime glass substrate, the light transmittance is reduced to 65% or less. that is, TL is, for example, reduced from 90% to more than 25%. Preferably, the light transmission factor TL is reduced by at least 35% and by 60% at the most, ie TL

  is reduced by 90% to between 55% and 30%.

  Preferably, the third layer of the shredder is preferably such that, when applied as a single layer to a 6 mm thick soda-lime glass substrate, the light transmittance is reduced to 54. , 5% at most, that is to say that TL is for example reduced

from 90% to more than 35.5%.

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  The following table gives the transmission (transmission factor

  luminous) TL obtained by different coatings on a substrate of soda glass

calcium of 6 mm.

Table IV

  Transmission Material Coating Thickness (Ti%) (nm) Nil 90 0 TiN 60 12 TiN 25 46

SS * 60 2

SS * 35.1 5

SS * 25 7.5

SSN 60 2

SSN 25 9.5

  * Note that stainless steel (SS) must be in non-oxidized form to achieve these results. If a layer of stainless steel becomes oxidized, for example during the deposition of a subsequent layer of oxide, the thickness of the stainless steel in non-oxidized form will be as given by these figures, in order to obtain the transmission established. Stainless steel oxide

  is not suitable for the first layer or the third layer.

  It is therefore preferable to use a thickness of between 12 and 25 nm when the material of the third layer is titanium nitride, to use a thickness of between 3 and 6 nm when the material of the third layer is stainless steel and to use a thickness of between 3 and 8 nm when the material of the third layer is "nitride" of stainless steel Increasing the thickness of this layer will reduce the total energy transmission and at the same time decrease the light transmission. The thickness of the absorbent layer will also have an effect on the

reflected color.

  When an intermediate layer of sacrificial metal is present, to obtain the best results, this layer will preferably have a thickness between 0 and 10 nm, for example not more than 6 nm, and preferably not more than 3 nm, to maintain a low emissivity of the layer

  of silver without substantially altering the reflected color.

  Usually, other coating layers are not present. Therefore, the first layer is deposited directly on the substrate and the fourth layer is an exposed layer. In a variant, the order of the layers is reversed, and the fourth layer is deposited directly on the substrate and the

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  first layer is an exposed layer. In this case (reversed order), the advantages of the invention, especially the purity of color, are obtained by

  observing the glazing from its coated surface.

  Glazing according to the invention can be manufactured by generally known methods, in particular successive vacuum deposition. A proven technique for depositing such layers is sputtering. This is conducted at very low pressure, specifically of the order of 0.3 Pa, to give a layer of coating material on the surface of the glazing. The process can be carried out under inert conditions, for example in the presence of argon, but it can alternatively be carried out as a reactive sputtering in the presence of a reactive gas. Therefore, in the manufacture of glazing according to the invention, when the first and fourth layers (of non-absorbent material) are in the form of oxides, these layers can be applied in the presence of oxygen. When the first and fourth layers (of non-absorbent material) are in the form of nitrides, these layers can be applied in the presence of nitrogen. The second layer should be applied in the presence of an inert gas such as argon. Especially in the case of rare, a mixture of argon and nitrogen, or even nitrogen alone can be used. The reaction between silver and nitrogen is not sufficient to form a nitride literally, but is sufficient to modify the mechanical properties of this layer. If a metal nitride is used for the third layer, it may be applied in the presence of nitrogen, which may, for reasons of convenience, be the

  same atmosphere as that used for the deposition of the second layer (silver).

  The particular advantages of the glazings according to the invention are such, under the preferred conditions, that the light transmission factor (TL) is greater than 30%, preferably between 30% and 65% measured on a glazing unit 6 mm thick or a factor equivalent for another thickness. In addition, the ratio of the light transmittance (TL) to the solar factor (FS) is at least 1.0, for example between 1.2 and 1.3. It is particularly advantageous for the glazings according to the present invention, that they have a blue tint in reflection from the face opposite to the coated face, the said color having a dominant wavelength of between 440 and 490 nm, preferably between 470 and 485 nm, ideally about 477 nm. The reflectivity of visible light from this face is preferably between 13% and 33%. In addition, the purity of the reflected blue color is greater than 15%, preferably greater than 30%, and is advantageously between 40% and 40%. The purity of a color is defined on a linear scale where a defined source of white light has a purity of zero and the pure color has a

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  100% purity. By the term "purity of color" as used herein is meant the excitation purity measured with illuminant C as defined in the International Lighting Vocabulary, published by the International Commission on Illumination. (CIE), 1987, pages 87 and 89. With solar glass according to the prior art, it has not been possible, for the same processes and manufacturing costs, to obtain reflected color purities as well. higher than those obtained with glazing according to the present invention. According to another preferred embodiment of the invention, a green reflected color is produced, having a dominant wavelength in the range 490nm to

520 rnm.

  Glazing according to the invention can be installed as single glazing or multiple glazing. In both cases, the advantages of the invention are best when the coated surface of the glazing is the inner face of the outer panel glazing. In this way the coated face is not exposed to ambient climatic conditions which could in the opposite case quickly reduce its life by soil, physical damage and / or oxidation. The glazings according to the invention can usefully be used in laminated structures, where the coated face is the internal face of the outer sheet. The invention will now be described in more detail, simply by way of example, with reference to the accompanying drawings in which: Figure 1 is a schematic section through a first glazing unit according to the invention; and FIG. 2 is a schematic section through a second glazing

according to the invention.

  Referring to Figure 1, a glazing unit 10 comprises a tempered glass substrate 12, 6 mm thick. The glass substrate has an outer surface 11 to be exposed to ambient climate conditions. A first coating layer 14 of zinc oxide, 65 nm

  thickness, is deposited directly on the inner face 13 of the glass substrate.

  This layer is deposited by reactive sputtering of zinc

  metal in an oxygen atmosphere at a pressure of 0.3 Pa.

  Directly on the zinc oxide layer 14, a layer 16 of silver with a thickness of 12 nm is deposited. This layer is deposited by cathodic sputtering of metallic silver in an argon atmosphere at a pressure of 0.3 Pa. Directly on the silver layer 16, a layer 18 of titanium nitride 20 nm thick is deposited. . This layer is deposited by reactive cathodic sputtering of metallic titanium in a nitrogen atmosphere at a pressure of 0.3 Pa. Directly on the layer of titanium nitride 18, an outer layer 20 of zinc oxide is finally deposited. 34 nm thick. This layer is deposited by reactive cathodic sputtering of

  zinc metal in an atmosphere of oxygen at a pressure of 0.3 Pa.

  The glazing described above has an intense blue color in reflection from the uncoated side. It is incorporated into a double-glazed structure with a 6 mm thick clear glass sheet and a 12 mm intermediate space. The coated face is positioned on the inner face of the outer sheet of the double glazing. The characteristics of the glazing as such (Example 1), and the double glazing (Example 2) are as follows:

Table Va

  Example 1 Example 2 Light Transmission Factor (TL) 45. 7% 40.7% Solar factor (FS) (CIE standard) 40.7% 30.0% X reflection peak (X dom.) 477 nm 477 nm Color purity 32.5% 30.0% Visible reflection (RL) 20.8% 22.5% Results in Example 1 can be compared as follows with the results obtained with a structure according to US 4,902,081 cited above.

(example C).

Table Vb

  Example 1 Example C * First layer 65 nm ZnO 40 nm ZnO Second layer 12 nm Ag 10 nm Ag Third layer 20 nm TiN 3 nm Ti Fourth layer 34 nm ZnO 35 nm ZnO Fifth layer - 24 nm TiN Transmission factor (TL) 45.7 % 25.5% X Reflection peak (X dom.) 477 nm 570 nm Color purity 32.5% 4.5% Visible reflection (RL) 20.8% 20.3% * - Comparative example It should be noted that the glazing according to US 4 902 081 has a low purity of color. The reflected color is greyish yellow

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  Examples 3 to 11 According to the procedure established with regard to Examples 1 and 2, other glazings according to the invention are prepared and, in the form of single sheets, they are found to have the following characteristics in reflection since the uncoated side.

Table VI

  Ex. ZnO Ag TiN ZnO TL RL X dom. purity (nm) (nm) (nm) (nm) (%) (%) (nm) (%)

3 10 5 14 30 47.2 17.9 480 25

4 55 8 36+ 30 47.2 18.9 476 34

56 8 28 37 54.8 18.1 477 34.4

6 60 11 18 40 46.5 21.5 477 31

7 60 5 24 50 44.6 17.7 477 30

8 60 * 8 14 45 * 56.6 15.6 476 36.5

9 80 6 14 40 55.9 13.4 476 48

100 5 18 20 39.5 14.9 477 33

11 10 6 14 40 48.9 23.9 483 25

  * - SnO2 is used instead of ZnO in Example 8.

  + - A single layer of TiN 36 nm thick on a glass substrate

6 mm would reduce TL from 90% to 33%.

  In Examples 4 and 5, the solar factor (FS) is also measured and the sheets are incorporated in double glazing with an uncoated glass sheet having a structure as previously described. The

The results are as follows.

  Table VII Ex. Single Sheet Double Glazing FS TL RL Purity FS (%) (%) (% /) (% o) (/%)

4 42.6 42 20.7 30.8 31.4

5 47.4 49 20.6 30.0 36.6

  Figure 2 shows a glazing similar to that shown in Figure 1, except that an intermediate layer 17 of titanium is interposed between the second layer 16 and the third layer 18. The thickness of the intermediate layer is 2 nm. The intermediate layer 17 is deposited by cathodic sputtering of titanium in an argon atmosphere at 0.3 Pa. The titanium metal layer 17 acts as a sacrificial metal interlayer to protect the silver layer 16, in particular the reaction with

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  oxygen which can diffuse through this layer, forming titanium oxide and avoiding a superficial alteration of the silver layer 16 which

  would lead to a loss of performance of the glazing.

  Examples 12 to 18 According to the procedure established with regard to Examples 1 and 2, other glazings according to the invention are prepared from a single glass substrate of 4 mm thickness, the layer (i) being applied to the substrate and the layer (iv) being an exposed layer. Products have been found to have the characteristics

  following in reflection from the uncoated side.

  Table Villa Layers: (i) (ii) (iii) (iv) Example No. (nm) (nm) (nm) 12 AIN Ag TiN AIN

61 10 14 41.5

Si3N4 Ag TiN Si3N4

61 11 12.5+ 39

14 ZnO Ag SSN # ZnO

9 7+ 50

ZnO Ag SS * ZnO

60 9 5.5+ 50

16 AIN AI TiN AIN

5 12+ 45

17 ZnO Ni TiN ZnO

7 12+ 55

18 ZnO Ni SSN # ZnO

7 5 55

Table VIIlb

  Properties: TL FS Xd purity RL Example No. (%) (%) (nm) (%) (%)

12 56.9 47.9 477 39 17.4

13 56.6 47.0 474 33 13.6

14 53.3 47.4 475 32 17.1

52.3 47.2 475 30 16.6

16 54.3 46.3 476 38 18.9

17 52.7 49.3 477 23 17.8

18 52.3 51.2 475 31 16.6

  Notes on Table VIII: * SS = 316 stainless steel (18/10) having the following composition: 18% Cr, 10% Ni, 2-3% Mo and at most: 0.08% C, 2% Mn , 0.045% P, 0.030% S and 1% Si. Note that stainless steel (SS) must be in non-oxidized form to obtain these results. Stainless steel oxide is not suitable for the first and third layers. If a layer of stainless steel is oxidized, for example during the deposition of a subsequent layer of oxide, the thickness of unoxidized stainless steel should be as given by these figures to obtain the established transmission. The thickness given in Table Villa for Example 15 (5.5 nm) is the unoxidized thickness, i.e. actually found in the final product. In order to obtain the structure according to this example, it is necessary to deposit a thin zinc barrier, as a sacrificial metal, on the stainless steel layer. When the zinc oxide is deposited, the sacrificial zinc oxidizes to form ZnO, which mixes with the deposited ZnO at the same time, thus protecting the stainless steel from oxidation. The thickness of the steel

  Stainless as such is determined in the product.

  #SSN = stainless steel nitride obtained by cathode sputtering using a stainless steel cathode in an atmosphere

  nitrogen. The exact composition of the resulting nitride is not known.

  + a single layer of TiN 12 nm thick on a glass substrate 6 mm thick would reduce TL by 90% to 60%, a single layer of TiN 12.5 nm thick on a glass substrate 6 mm thick would reduce TL by 90% to 58%, a single layer of 7 nm thick SSN on a 6 mm thick glass substrate would reduce TL by 90% to 35%, a single layer of SS 5.5 nm thick on a 6 mm glass substrate

  thick would reduce TL from 90% to 32%.

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Claims (14)

  1. Transparent solar protection glazing characterized in that it comprises a substrate having a coating consisting of: (i) a first layer comprising a non-absorbent material; (ii) a second layer selected from materials for which the spectral absorption index k (X), for wavelengths (X) between 380 and 780 nm, is greater than the refractive index n ( X) and, whose spectral absoption index k (X), at the wavelength (X) of 550 nm, is greater than 1.67 times the refractive index n (X); (iii) a third layer comprising an absorbing material for which the spectral absorption index k (X), for wavelengths (X) between 380 and 780 nm, is between 0.3 and 1, 0 times the refractive index n (X) of the material, said third layer having a thickness such that, when applied as a single layer on a 6 mm thick soda-lime glass substrate, its light transmission factor TL is reduced by at least 30%; and   (iv) a fourth layer comprising a non-absorbent material.   Transparent solar protection glazing according to claim 1, characterized in that the non-absorbent material of the first and fourth layers has a refractive index greater than 10 times the absorption index.   spectral range of the material at wavelengths between 380 and 780 nm.   3. Transparent solar protection glazing according to one of the   1 or 2, characterized in that the non-absorbent material of   first and fourth layers are independently selected from silicon and aluminum nitrides, aluminum oxynitride, aluminum, bismuth, silicon (SiO and SiO2), tin, titanium and zinc oxides , and their mixtures,   preferably selected from Si3N4, AlN, ZnO, SnO2 and TiO2.   4. Transparent solar protection glazing according to rune   Claims 1 to 3, characterized in that the material of the second layer is money.   5. Transparent solar protection glazing according to one of the   Claims 1 to 4, characterized in that the material of the third layer is   selected from stainless steel, nitrides of titanium, chromium, and alloys   aluminum / titanium, the "nitrides" of stainless steel and their mixtures.   6. Transparent solar protection glazing according to one of the   Claims 1 to 5, characterized in that the optical thickness of the first layer is at least 100 nm.   7. Transparent solar protection glazing according to one of the   Claims 1 to 6, characterized in that the optical thickness of the first and   fourth layer is between 180 and 270 nm.   8. Transparent solar protection glazing according to one of the   Claims 1 to 7, characterized in that the optical thickness of the first   layer is greater than that of the fourth layer.   9. Transparent solar protection glazing according to one of the   Claims 1 to 8, characterized in that the thinner of the third layer is   such that, when applied as a single layer to a 6 mm thick soda-lime glass substrate, its light transmittance TL is reduced by at most 65%, preferably at least 35%, and 60% at the most. 10. Transparent solar protection glazing according to one of the   Claims 1 to 9, characterized in that the first layer is deposited   directly on the substrate and the fourth layer is an exposed layer.   11. Transparent solar protection glazing according to one of the   Claims 1 to 10, characterized in that it has a transmission factor   (TL) between 30% and 65%, measured on 6 mm glazing of épaissseur.   12. Transparent solar protection glazing according to one of the   Claims 1 to 11, characterized in that the ratio of the   light transmission (T [) on solar factor (FS) is at least 1.0.   13. Transparent solar protection glazing according to one of the   Claims 1 to 12, characterized in that it has a blue color in   reflection from the face opposite to the coated face, said blue color having a wavelength of maximum intensity of between 440 and 490 nm,   preferably between 470 and 485 nm.   14. Transparent solar protection glazing according to one of the   Claims 1 to 13, characterized in that it has a purity of color   reflected greater than 15%, preferably greater than 30%.