Solar-protection glazing having an improved light transmission coefficient

Translation of description of equivalent WO 2009112759 A2

p0001GLAZED sunscreen HAVING IMPROVED LIGHT TRANSMISSION FACTOR

p0002The invention relates to glazing provided with thin-film layers of which at least one is functional, that is to say, it acts on the solar radiation. The present invention relates more particularly to glass layer (s) including those intended for the thermal and / or solar protection.

p0003layer is defined as "functional" in the sense of the present application, the layer or layers of the stack, which gives the most stack of thermal properties, as opposed to other layers, usually of dielectric material and having based chemical or mechanical protection of said functional layers, or other function for example optical, adhesion, etc ..

p0004Sunscreen glazing according to the invention are particularly suitable for equipping buildings by limiting, thanks to the thin layers, the amount of energy transmitted by solar radiation, they avoid overheating inside the premises summer and thus helps to reduce energy consumption necessary for their air conditioning.

p0005Also provided this type of glazing covered once said thin layers, to obtain a front facing panel, so called classic lighter, and which, in combination with window glazing, d provide exterior surfaces are entirely glazed.

p0006sunscreen functional layers glazing are subject to a number of constraints: first, employees layers must be sufficiently filter vis-à-vis solar radiation, particularly vis-à-vis the part of the non-visible solar radiation and between about 780 nm and 2500 nm, commonly called solar infrared (IR solar). In addition, these thermal performance must preserve the optical appearance, aesthetics glass: it is in particular desirable to modulate the level of light transmission (T_L) Of the substrate. In another important aspect, the functional layers must also be sufficiently durable and particularly resistant to physical stresses such as scratches and chemical stresses; they must be especially resistant to moisture. This is especially important if, in the glazing once fitted, they are on one of the external faces of the glazing (as opposed to "interior" faces turned toward the intermediate gas-filled double glazing for example ) or whether the glazing is single glazing, that is to say comprising a single glass sheet.

p0007Another constraint is also required during the preparation of glazing: when those -ci consist at least partly of glass substrates, they must often undergo one or more heat treatments may be a bending operation if one wants their impart a curve (window) but is usually a tempering or annealing, especially in the construction sector where they are to be more resistant and less dangerous in the event of shocks. The fact that the layers are deposited on the glass before heat treatment often causes deterioration and a significant change to their properties, particularly optical. Conversely, deposit the films after heat treatment of the glass is complex and expensive.

p0008An example of solar-protection glazing for buildings is given in patents EP-O 511 901 and EP-O 678 483: it is functional layers in terms of filtering solar radiation that are nickel-chromium alloy optionally nitrided stainless steel or tantalum, and are arranged between two dielectric layers of metal oxide such as SnO₂, TiO₂ or Ta₂O₅. These glazings are good anti-solar glazing, having satisfactory mechanical and chemical durabilities, but are not truly "bendable" or "hardenable" in the sense previously described, because the oxide layers surrounding the functional layer can prevent oxidation during bending or tempering, said oxidation being accompanied by a significant change in light transmission, as well as the general appearance of the glazing in its entirety.

p0009More recently, it has been proposed in the patent application EP 1218307, a sun piling whose functional layer comprises a metal selected from Nb, Ta, Zr, optionally nitrided, the functional layer being surmounted protective layers based on nitrided or aluminum oxynitride or silicon. The stack according to this application gives the glazing a solar-protection function to block solar IR of incident solar radiation. Furthermore, this stack has proven resistant to quenching and durable enough mechanically and chemically for use on face 2 of single glazing. The major drawback of the stack described in EP 1218307, however, is that the functional layer is relatively thick, so as to obtain the sunscreen effect sought, and it has thereby a T_L very low, around 10% or even less.

p0010The object of the invention is thus to significantly increase the light transmission T_L such a sunscreen glazing, without such an increase would lead to a significant reduction in thermal insulating properties of the glazing, which can lead to excessive heat transfer between the inside and outside of the building or the passenger protected by said glazing.

p0011Known in the field of glazing likely to respond to such a request. These windows are made up of one or more functional thin layers of metallic silver Ag. Such glasses are described for example in Patent Application EP 718250. The integration windows of one or more layers of silver allows so well known to greatly reduce heat transfer through the glazing, because of the low emissive nature of the Ag layers, that is to say thanks to their ability to reflect a large part of the thermal IR, located between 3 and 50 microns. It is then possible to obtain, according to well known techniques and in particular by the addition of interference layers of dielectric index material and of suitable thickness, glazings having high light transmission but the heat transfer coefficient remains very low.

p0012Solar control layers based on thin silver layers and appear very efficient for thermal insulation but their mechanical and chemical durability is very limited, especially in contact with a humid atmosphere and does not allow in particular their use for single glazing. Furthermore this solution is relatively expensive to implement for double glazing.

p0013The invention therefore consists in the development of new stacks of thin layers acting on solar radiation, to manufacture improved solar protection glazings. The improvement is particularly referred restore a better balance between durability, thermal, optical and solar-protection function, particularly light transmission, and ability to withstand heat treatments without damage when stacking the carrier substrate of the glass type. More specifically, the object of the present invention is therefore to provide a glazing provided with thin layers conferring good anti-solar properties, light transmission greater than or equal to 10 or even 20%, but still allowing maintain an acceptable heat transfer coefficient in particular through an emissivity coefficient α, as defined in prEN 410, low enough, said glazing provided with said layer can also be heat treated, in the sense explained above.

p0014According to the invention, such a simple or multiple glazing could be obtained having especially: - a light transmission greater than or equal to 10% or even above 20% or even 30% or even 40%,

p0015- An emissivity less than or equal to 50%, preferably less than 40% or even 30% or even 20%,

p0016- Resistance to a heat treatment such as a bending or tempering, including the preservation of the above properties and a chemical resistance, in the sense previously described,

p0017- Good chemical and mechanical durability.

p0018The object of the invention therefore consists firstly in a transparent glass substrate, comprising at least a glass sheet provided with a stack of thin layers acting on solar radiation, having a light transmission greater than or equal to 10%, or even 20% or equal upper and a emissivity less than or equal to 50% or even less than 40% or even less than 30% or 20% after a heat treatment such as a bending or tempering, said stack comprising : - a functional layer based on Niobium Nb, with a thickness between about 5 nm and about 35 nm,

p0019- At least one layer of another material, chosen from the group consisting of Ti, Mo, B, Al or an alloy comprising at least one of these elements, arranged with respect to the glass substrate over the layer functional, said layer having a thickness between about 1 nm and about 5 nm.

p0020According to one possible embodiment, the transparent glass substrate comprises at least a glass sheet provided with a stack of thin layers acting on solar radiation, having a light transmission greater than or equal to 20% and an emissivity less than or equal to 50% after a thermal processing such as bending or tempering, said stack comprising:

p0021- A functional layer of niobium Nb, with a thickness between about 5 nm and about 25 nm, - at least one layer of another material, chosen from the group consisting of Ti, Mo, B, Al or an alloy comprising at least one of these elements, arranged with respect to the glass substrate above the functional layer, said layer having a thickness between about 1 nm and about 5 nm. Preferably, a layer of said material selected from the group consisting of Ti, Mo, B, Al is arranged above the functional layer and another layer of said material is disposed beneath the functional layer.

p0022Typically, the function layer tional based Niobium Nb has a thickness of between about 8 nm and about 20 nm, for example between 8 and 15 nm. Typically, the layer of material selected from the group consisting of Ti,

p0023Mo, B, Al has a thickness between about 1 nm and about 3 nm. Preferably, said material is Ti.

p0024According to the invention, all of the functional layer and the layer or layers (s) of said material is surrounded by at least one additional layer based on aluminum nitride, aluminum oxynitride, nitride of silicon, or silicon oxynitride, or a mixture of at least two of these compounds, the thickness of the said further layers being adjusted to optimize the light transmission of the glazing.

p0025For example, said one or more additional layers are based on silicon nitride and are disposed respectively above and below said set.

p0026According to one possible embodiment, the silicon nitride layer disposed above said assembly is thicker than the layer disposed below the set of at least a factor of 1, 2, especially at least a factor of 1, 5 to 1, 8. Of course, in the context of the present invention, all particular combinations between two or more values ​​and / or previous intervals, are contemplated, even if they are not specifically disclosed, for reasons of clarity. The invention also relates to a monolithic glazing or double glazing incorporating the substrate as described above, the thin-film stack being disposed on face 2 of monolithic glazing or double glazing or face 3 of the double glazing, numbering the faces of or outside substrates inwardly of the building or the passenger compartment it equips. According to one embodiment, the monolithic glazing or double glazing is configured to have a light transmission T_L greater than 10%, or 20%, or even greater than 30% or even above 40%. Monolithic glazing or double glazing may also be configured to have an emissivity less than 40% or even less than 30% or even less than 20%. Finally, the present invention relates to type on wall spandrel panel incorporating at least one substrate as described above or a side window, a rear window or an automobile roof or other vehicle consisting of or incorporating said substrate.

p0027According to the invention, the functional layers according to the invention provide a light transmission value of the relatively high substrate while maintaining a sunscreen effect notable, despite the relatively small thickness of the functional layer: measures done indeed show a good compromise between the level of light transmission T_L and the heat transfer coefficient U of the layered substrate, as measured by its α emissivity. In this specification the α Emissivity is the normal emissivity as defined in the standard prEN410.

p0028The use of a very thin layer of a metal of group Ti, Mo, B, Al, particularly Ti, according to the invention allows to ensure the hardenability of the stack of layers without joint degradation of the functional properties of those -this. In particular, the change in optical properties including light transmission, induced by heat treatment of the toughening type, is low. Similarly, the emissivity of the functional layer remains low thanks to the contribution of this additional thin metal layer. In one possible embodiment of the invention, the metal thin layer of the group Ti, Mo, B, Al is deposited at least on top of the functional layer of Nb. Preferably said layer is deposited above and below the layer of Nb. The terms "above" and "below", reference is made herein to the respective position of said layers compared to the glass substrate supporting stacking said layers.

p0029According to one embodiment of the invention, it is preferable to also file an overlayer based on silicon or aluminum nitride (NHIS₄ and abbreviated AIN) or silicon oxynitride or aluminum (SiON and AINO abbreviated, without prejudice to the respective amounts of Si, O and N). The adjustment of the thickness of such layers is performed so as to obtain an antireflection effect for optimizing the light transmission of the coated glass. Such layers may also, to a lesser extent, a role in protecting the functional layers of the invention. Within the scope of the invention, it is also possible according to the invention to dope these layers with elements Zr type B, etc., so as to change the color in transmission and / or reflection of the glazing, according techniques well known in the art.

p0030Preferably, the stack of layers according to the invention comprises between the substrate and the functional layer, at least one sublayer made of transparent dielectric material, especially chosen, as for the overcoat layer, silicon nitride or oxynitride and / or nitride or aluminum oxynitride, or silicon oxide in SiO2. Its presence may especially allow to adjust more flexibly the optical appearance conferred by the multilayer substrate holder thereof. In addition, in case of heat treatment, it may be an additional barrier, especially vis-à-vis oxygen and alkali metals from the glass substrate, species capable of migrating to the heat and degrade the stack.

p0031A very preferred embodiment of the invention may for example be to use both a topcoat and a sublayer based on silicon nitride.

p0032The thickness of the overcoat layer is preferably between 5 and 70, especially between 40 and 60 nm. The thickness of the optional sub-layer is preferably between 5 and 120 nm. When there is a single sublayer of the Si₃NOT₄It is for example between 30 and 50 nm.

p0033The undercoat and / or overcoat layer may in fact be part of a superposition of layers of dielectric material. One or the other can thus be associated with other different refractive index layers. Thus, the multilayer stack may include between the substrate and the functional layer (or above the functional layer) alternating three high index layers / low index / high index layer "high index" (at least 1, 8-2) or one of them being the sublayer of the type of invention SISN₄, AlN, and the layer "low index" (less than 1, 7 for example) which can be SiO 2 silicon oxide.

p0034In particular, a very preferred embodiment of the invention consists of a single or multiple glazing comprising a substrate on which is deposited a stack including a functional layer based on niobium surmounted both sides by a layer of Ti, all the layers Ti / Nb / Ti being itself surmounted by an overlayer based on silicon nitride and also by a sub-layer based on silicon nitride.

p0035The invention as well for simple object or "monolithic" glazing, that is to say consisting of a single substrate, the multiple glazing insulating double glazing type. Preferably, whether monolithic glazing or double glazing, the stacks of layers are arranged on face 2

p0036(Conventionally, are numbered faces of glasses / substrates an outside glazing inwardly of the passenger compartment / room which is team), and provide a protective effect against the solar radiation. Within the scope of the invention, the multilayer coatings can be deposited on face 3 of the double glazing.

p0037The invention also relates to the layered substrate at least partially clouded by a coating of paint or enamel to make lighters where the opacifying coating is in direct contact with the stack of layers. The multilayer stack can thus be perfectly identical for glazing vision and spandrel.

p0038If the application specifically targeted by the invention is glazing for buildings, it is clear that other applications are possible, especially in vehicle glazing (except the windshield where it requires a very high light transmission), such as side windows, sunroof, rear window.

p0039The invention and its advantages are described in more detail hereinafter by means of nonlimiting examples below, according to the invention and comparative. In all the examples and the description, the thicknesses are geometrical.

p0040All substrates are clear glass 6mm thickness Planilux type sold by Saint-Gobain Vitrage.

p0041All layers are deposited in a known manner by sputtering assisted by magnetic field (magnetron). The metal layers

p0042(Nb, Ti) are deposited from inerting metal targets (100%

p0043Ar), layers of silicon nitride Si₃NOT₄ from the silicon target (doped with 8% aluminum by weight) proper in a reactive atmosphere containing nitrogen (40% Ar and 60% N₂). If the layers₃NOT₄ therefore contain some aluminum.

p0044EXAMPLE 1 (according to EP 1218307)

p0045This example shows a Nb functional layer and undercoat and overcoat Si₃NOT₄ in the following sequence: glass / Si₃NOT₄ (10 nm) / Nb (35 nm) / Si₃NOT₄ (30 nm)

p0046After deposition of the layers, the substrate subjected to the following thermal treatment: heating to 620⁰C for 10 minutes and then tempering.

p0047EXAMPLE 2 (Comparative) In this example, use the same functional layer and other layers the same as in Example 1, deposited on the same substrate, but with changes in the thicknesses of the sublayers and overcoat Si₃NOT₄: Glass / Si₃NOT₄ (40 nm) / Nb (10 nm) / Si₃NOT₄ (60 nm) The coated substrate of the stack is then subjected to the same heat treatment as described in Example 1.

p0048Example 3 (Invention)

p0049This example uses the same sequence of layers as in Example 2, deposited on the same substrate, but a very thin layer of metal is Titanium deposited above the functional layer. The stack thus comprises the following sequence of layers: glass / Si₃NOT₄ (40 nm) / Nb (10 nm) / Ti (about 1 nm) / Si₃NOT₄ (60 nm) The coated substrate of the stack is then subjected to the same heat treatment as described in Example 1 or 2.

p0050Example 4 (comparative)

p0051This example uses the same sequence of layers as in Example 2, deposited on the same substrate, but a very thin layer of titanium metal is deposited beneath the functional layer. The stack thus comprises the following sequence of layers: glass / Si₃NOT₄ (40 nm) / Ti (about 1 nm) / Nb (10 nm) / Si₃NOT₄ (60 nm) The coated substrate of the stack is then subjected to the same heat treatment as described in Example 1 or 2.

p0052Example 5 (Invention)

p0053This example uses the same sequence of layers as in Example 2, deposited on the same substrate, but a very thin layer of titanium metal is deposited above and below the functional layer. The stack thus comprises the following sequence of layers: glass / Si₃NOT₄ (40 nm) / Ti (≈1 nm) / Nb (10 nm) / Ti (≈1 nm) / Si₃NOT₄ (60 nm) The coated substrate of the stack is then subjected to the same heat treatment as described in Example 1 or 2.

p0054EXAMPLE 5b (Invention)

p0055This example uses the same sequence of layers as in Example 5, deposited on the same substrate. The stack thus comprises the following sequence of layers: glass / Si₃NOT₄ (40 nm) / Ti (≈1 nm) / Nb (19 nm) / Ti (≈1 nm) / Si₃NOT₄ (50 nm) The coated substrate of the stack is then subjected to the same heat treatment as described in Example 1 or 2. EXAMPLE 6 (comparative)

p0056This example uses the same sequence of layers as in Example 2, deposited on the same substrate, but a very thin layer of NiCr is deposited above and below the functional layer. The stack thus comprises the following sequence of layers: glass / Si₃NOT₄ (40 nm) / NiCr (≈1 nm) / Nb (10 nm) / NiCr (≈1 nm) / Si₃NOT₄ (60 nm)

p0057The coated substrate of the stack is then subjected to the same heat treatment as described in Example 1 or 2.

p0058Table 1 below for Examples 1-6 previous measured data of optical transmission T_L (% Light transmission under illuminant D₆s) and the emissivity value α, calculated according to the standards and prEN410 NFEN 673. The data are shown twice: before heat treatment and after heat treatment. It was also reported in Table 1 the relative increase Δα, in percentage, of the emissivity value α after quenching.

p0059<img id="imgf000013_0001" he="152" wi="134" file="imgf000013_0001.tif" img-format="tif" img-content="table" orientation="portrait" inline="no" />

p0060Table 1

p0061The data reported in Table 1 show that Examples 3, 5 and 5b of the invention can provide a much higher light transmission than sunscreen glazing of the prior art, as maintaining acceptable energy performance after heat treatment and quenching. Comparison of emissivity values ​​obtained after quenching for Example 4 with the values ​​obtained for examples 3, 5 and 5b show that the best compromise is obtained when a Ti metal layer is deposited at least above the layer No. functional. The results for Example 2, not in accordance with the present invention (the stack being free of layer (s) metal (s) of Ti), are worse after quenching: these stacks are clearly not bendable / toughenable within the meaning of the invention. The heat treatment degrades so too much thermal insulation properties: emissivity values ​​of these glazings thus appear much too high. The results obtained according to Example 6, wherein the metal layer deposited on the functional layer is NiCr this time are similar to those obtained for Example 2, that is to say in the absence of layer.

p0062EXAMPLE 7 (Invention)

p0063For this example, a multiple glazing has been built from the substrate of Example 5 (after quenching).

p0064The multiple glazing is assembled according to conventional techniques in a configuration 6/12/6^claιr (100% air), that is to say such that it is composed of two sheets of clear glass 6mm thick, separated by an air gap of 12 mm. The stack of layers is arranged face 2 of the double glazing. Double glazing has a light transmission of 36% but a value of the relatively low emissivity of about 37%, enabling the reflection of a major portion of the thermal infrared radiation. The energy insulation performance is therefore very satisfactory, U heat transfer coefficient has been measured to be 2.30 W. m^"2. K^"1. For comparison, the U-value is equal to 2.90 W m^"2. K^"1 for a simple double glazing without layers. Also for comparison, the low-emissivity transparent glazing of the prior art, incorporating as a functional layer hardly tempered silver layer, have a coefficient of the order of 1, 8 W. m^"2. K^"1But are much durable, both in terms of chemical and mechanical resistance.

p0065EXAMPLE 8 (Invention)

p0066In this example, we sought a multiple glazing from a substrate having the layers of the stack have thicknesses adapted to maximize this time the energy performance of the glazing. The stack thus comprises the following sequence of layers: glass / Si₃NOT₄ (40 nm) / Ti (≈1 nm) / Nb (20 nm) / Ti (≈1 nm) / Si₃NOT₄ (54 nm) The coated substrate of the stack is then subjected to the same heat treatment as described above. was then made a multiple glazing from this substrate. Similar to Example 7, the multiple glazing is assembled in a configuration 6/12/6^claιr (100% air). The stack of layers is arranged face 2 of the double glazing.

p0067Double glazing and has a light transmission of about 20%, lower than that of Example 5, but a value of the emissivity much lower, about 18%, for a strong reflection of thermal radiation and greatly improved energy insulation performance, the heat transfer coefficient U this time having been measured to be 1, 98 Wm^"2.K^"1. Finally, sun protection glazing according to the invention are highly advantageous for equipping buildings, without excluding applications in the automotive and other vehicles: the side windows, rear, sunroof, which may also submit enamel coatings. With a stack of fixed layers, in particular according to the values ​​of T_L and popular thermal insulation, one can thus make sunscreen glazing for improved vision and can be bent / toughened / annealed and having a very good mechanical and chemical durability.

p0068Without departing from the scope of the invention, one can also make lighters enamelled layers, rather than coated, which is industrially very interesting, linking taking place during the quenching process, while the coating requires an additional manufacturing step.