Glazing with variable optical and/or energetic characteristics

The present invention relates to glazing with variable optical / energy properties. It relates more precisely to glazing whose certain characteristics can be modified for example under the effect of an electrical supply, for example light scattering or the transmission in certain wavelengths of electromagnetic radiation, in particular in infrared and / or in the visible, or under the effect of a particular radiation.

There is indeed an increasingly increased demand for so-called “intelligent” glazing, that is to say glazing the properties of which can be modulated at will, in particular in order to take account of different evolutionary parameters. Thus, it can prove to be very advantageous to be able to control the solar contribution through glazing mounted outside in buildings or vehicles of the automobile or train type, in order to avoid excessive heating of the parts or cockpits in strong sunshine. Likewise, it may be useful to be able to control the degree of vision through glazing, for example in the case of glazing used as internal partitions between two rooms, in a building, or between two compartments, in a means of transport of the type train or plane. Many other applications also exist for such glazing: mention may be made, for example, of vehicle mirrors, which, by darkening when necessary, can prevent the driver from being dazzled, or road or urban traffic signs, only showing messages or designs intermittently to better draw attention.

The interest that such glazing can arouse justifies that many systems have already been studied.

Thus, known systems making it possible to modulate the light transmission or absorption of glazing are in particular the so-called viologen systems, such as those described in patent US-5,239,406 or in patent EP-A-0 612 826. These allow to obtain a variable absorption essentially in the visible range.

For the same purpose, there are also so-called electrochromic systems whose operating principle is briefly recalled: these, in known manner, comprise a layer of electrochromic material capable of reversibly and simultaneously inserting cations and electrons and whose oxidation states corresponding to the inserted and uninserted states are of distinct coloring, one of the states having a higher light transmission than the other. The insertion or deactivation reaction is controlled by an adequate power supply using a current generator or a voltage generator. The electrochromic material, usually based on tungsten oxide, must thus be brought into contact with an electron source such as a transparent electroconductive layer and with a source of cations such as an ion conducting electrolyte.

Furthermore, it is known that to ensure at least a hundred switching operations, there must be associated with the layer of electrochromic material a counter-electrode capable also of reversibly inserting cations, symmetrically with respect to the layer of material. electrochromic, so that, macroscopically, the electrolyte appears as a simple medium for cations.

The counter-electrode must consist of either a neutral layer in coloring, or at least transparent or little colored when the electrochromic layer is in the discolored state. Since tungsten oxide is a cathodic electrochromic material, that is to say that its colored state corresponds to the most reduced state, an anodic electrochromic material such as nickel oxide or iridium oxide is generally used for the counter electrode. It has also been proposed to use an optically neutral material in the oxidation states concerned, such as for example cerium oxide or organic materials such as electronic conductive polymers (polyaniline, etc.) or prussian blue.

The description of such systems can be found for example in European patents EP-0 338 876, EP-0 408 427, EP-0 575 207 and EP-0 628 849.

Currently, these systems can be divided into two categories, depending on the type of electrolyte they use:<ul id="ul0001" list-style="dash" compact="compact"><li>either the electrolyte is in the form of a polymer or a gel, for example a proton-conducting polymer such as those described in European patents EP-0 253 713 and EP-0 670 346, or a polymer with conduction of lithium ions such as those described in patents EP-0 382 623, EP-0 518 754 or EP-0 532 408,</li><li>or the electrolyte is a mineral layer, ionic conductor but electronically insulating, we then speak of “all solid” electrochromic systems. For the description of an “all solid” electrochromic system, reference may be made to the French patent application filed on March 27, 1996 under the filing number FR-96/03799.</li></ul>

These systems with reversible insertion material (s) are particularly interesting in that they make it possible to modulate the absorption in a wider wavelength range than the viologen systems: they can absorb in a variable way not only in the visible, but also, in particular, in the infrared, which can give them an effective optical and / or thermal role.

The viologenic or electrochromic systems, deposited or associated with transparent substrates constitute glazing whose absorption and light transmission (as well as energy transmission) can vary within given ranges, ranges determined in particular by the choice of electrochromic materials used and / or by the choice of their thickness.

Another type of “intelligent” glazing is constituted by what is designated by the term of optical valve: it is a film comprising a generally crosslinked polymer matrix in which are dispersed micro-droplets containing particles which have the property of being placed in a preferred direction under the action of an electric or magnetic field.

Depending in particular on the potential applied to the terminals of the conductive layers placed on either side of the film, and on the concentration and the nature of the orientable particles, the film has variable optical properties.

Thus, it is known from patent WO-93/09460 an optical valve based on a film comprising a crosslinkable polyorganosilane matrix and orientable mineral or organic particles, more particularly light absorbing particles such as polyiodide particles. When the film is turned on, the particles intercept light much less than when it is turned off.

Glazing with a similar operating principle is also known as liquid crystal glazing. It is based on the use of a film placed between two conductive layers and based on a polymeric material in which are dispersed droplets of liquid crystals, in particular nematic with positive dielectric anisotropy. The liquid crystals, when the film is tensioned, orient themselves along a privileged axis, which allows vision. When switched off, in the absence of alignment of the crystals, the film becomes diffusing and prevents vision.

Examples of such films are described in particular in European patents EP-0 238 164, and American patents US-4 435 047, US-4 806 922, US-4 732 456. This type of film, once laminated and incorporated between two glass substrates, is sold by SAINT-GOBAIN VITRAGE under the trade name "Priva-lite".

One can in fact use all the liquid crystal devices known under the terms of "NCAP" (Nematic Curvilinearly Aligned Phases) or "PDLC" (Polymer Dispersed Liquid Crystal).

It is also possible to use, for example, gels based on cholesteric liquid crystals containing a small amount of crosslinked polymer, such as those described in patent WO-92/19695.

There are also so-called photochromic glazing, whose absorption property in the visible and possibly in at least part of the infrared, is adjustable under the effect of energy radiation, generally located in the ultraviolet. There are mainly two families: the first uses as active elements silver salts, in particular silver halides for example in a glass matrix, halides which by absorption in the ultraviolet are reversibly put in the form of metallic aggregates . The second family uses as active elements organic dyes generally dispersed in a polymer matrix, in particular compounds derived from spiroxazines and spiropyranes. By absorption in the ultraviolet, these compounds are reversibly isomerized.

However, all of these glazings have intrinsic limits, limits which relate in particular on the one hand to their thermal resistance and on the other hand to their optical appearance.

In fact, these glazings comprise a plurality of electrically and / or electrochemically active components, the durability of which may depend on the temperature to which they are subjected. In the particular case of glazing with variable light transmission such as electrochromic glazing, when these are in the colored state, they are highly energy absorbing. However, when they are used as exterior glazing, and even more so if they are mounted inclined relative to the vertical (which is the case for automotive glazing such as auto roofs or building roof glazing), they can , in the colored state, if they are subjected to a strong sunshine long enough, heat up to high temperatures reaching 80 ° C. However, such temperatures can cause a shortening of the life of the glazing by irreversible progressive degradation of one or other of their electrochemical components.

The same type of problem can also arise for glazing with variable light diffusion, such as liquid crystal glazing, firstly because above a certain temperature called the lightening point, the polymer-liquid crystal composite, put in diffusing state, can spontaneously return to transparent state. Then, if a dichroic dye has been added to the composite in order to be able to jointly modulate the diffusion and the light transmission of the glazing, this type of dye exhibits a certain instability with respect to ultraviolet rays, instability increasing with temperature.

Photochromic glazing also has a drawback linked to its heating. Indeed, the two families of photochromic glazing mentioned above are tinted under the effect of ultraviolet, “unstable” state, the return to the “stable”, discolored state being obtained by a process which is thermally activated. Under the effect of ultraviolet rays, these glazing colors, become absorbent, and therefore heat up. In case of strong sunshine, the heating becomes excessive and tends to cause the glazing to return to its stable, discolored state: the "accessible" contrast decreases.

Furthermore, the optical appearance of these glazings may not be fully satisfactory depending on the intended applications. Thus, when an entire facade of a building is fitted with electrochromic glazing, it can be estimated that they offer a somewhat dark overall appearance when they are all in the colored state. It could also be interesting to be able to better adjust the reflection aspect of an electrochromic glazing fitted to a car according to the color of the exterior bodywork. Likewise, liquid crystal glazing offers, in the diffusing state, a milky white appearance, (in the absence of dye) identical whatever the side where the observer is. However, it could prove advantageous to succeed in eliminating this symmetry of appearance for aesthetic reasons.

The object of the invention is therefore to overcome these drawbacks, in particular by proposing new glazings with variable optical and / or energy properties, in particular electrocontrollable or photochromic, which have greater thermal durability and / or which can be more modulated. optical appearance.

The subject of the invention is a glazing unit comprising at least one active system with variable optical and / or energetic properties, in particular electrocontrollable of the system type with variable light transmission / absorption or of the system type with variable light diffusion, or of the photochromic type. This glazing further comprises at least one means of thermal protection with respect to the electrocontrollable system and / or for adjusting the optical appearance imparted by the electrocontrollable system to the glazing. This means is advantageously in the form of at least one coating with reflection properties in the infrared and / or in the visible and / or in the ultra-violet:

Depending on its configuration in the glazing, this reflective coating can in fact assume two functions alternately or cumulatively.

When the coating is placed in the glazing so that, once the glazing is installed, it is between a heat source and the active (electrochemical) system, it acts as a thermal shield, reflecting all or part of the energy emitted by the heat source. It thus avoids excessive heating of the active system of the electrochemical type. The most interesting application concerns glazings mounted outdoors fitted to buildings or vehicles and intended to be exposed to long periods of sunshine. It particularly targets electrochromic glazing which, in the colored state and in the absence of a thermal "filter", can heat up strongly by energy absorption, heating which is harmful for the life of the glazing and even for safety problems. , the surface temperature of the glazing unit being able, without thermal filter, to reach 80 ° C.

It also targets active glazings of the photochromic type, which, as mentioned above, tend to lose their properties in the event of excessive heating.

Two very advantageous consequences follow from this:<ul id="ul0002" list-style="none" compact="compact"><li>□ on the one hand, the invention makes it possible to extend the life of “intelligent” glazing which was already intended for outdoor applications. This is commercially and technically very interesting, both in the building sector where manufacturers must guarantee the lifespan of the materials used of at least 5 or 10 years, as in the automotive sector where safety standards prevail severe, in terms of optical quality in particular,</li><li>□ on the other hand, the invention makes it possible to envisage, for outdoor applications, “intelligent” glazing hitherto used essentially indoors for reasons of too low thermal durability, and / or instability vis-à-vis of certain radiations which is for example the case of certain liquid crystal glazings using dichroic dyes which are relatively unstable with respect to ultraviolet radiation.</li></ul>

The reflective coating according to the invention can also be given a very advantageous optical role, by selecting it so that it modulates the optical appearance and therefore the aesthetics of the glazing. One can think, without limitation, of two very advantageous types of “optical modulation”.

For glazing with variable light transmission / absorption of the electrochromic type, it was seen above that the type of electrochemical system chosen made it possible to fix the terminals between which the light transmission or absorption of the glazing would be able to vary. It is the same for the choice of the aspect in colorimetry of the glazing. Thus the choice of an electrochromic system using as tungsten oxide cathodic electrochromic material will lead to a glazing whose color will be in blues.

Combining with such a system a reflective coating, the optical properties of which can be precisely adjusted, in particular by choosing its composition and thickness, makes it possible to adapt the optical appearance of the glazing in different ways: by appropriately selecting the reflective coating, the range of light transmission of the glazing can be lowered in a controlled manner, without significantly reducing its contrast (contrast being defined as the ratio of light transmission to the completely discolored state and to the completely colored state). In addition, the reflective coating can have a colorimetric impact on the glazing, by modifying the color of the latter on one or other of its faces.

These remarks also apply to active glazings of the photochromic type: the reflective coating limits their heating therefore preserves their properties, and can also modulate their optical properties.

Furthermore, the reflective coating can also be very attractive from an aesthetic point of view when incorporated into a glazing with variable light diffusion of the liquid crystal type. With this type of glazing, we generally have an absolutely "symmetrical" appearance whatever the side where the observer is located, transparent appearance in the non-diffusing state and appearance often in milky white in the diffusing state, this is the case of glazing currently sold under the name of "Priva-lite" by SAINT-GOBAIN VITRAGE. Now, for particular applications, we now wish to achieve a different optical appearance depending on the side where the observer is located. The reflective coating according to the invention makes it possible to achieve this result, since a glazing provided with both the variable light diffusion system and the reflective coating has, in particular in the diffusing state, a face which will retain the diffusing appearance , white and milky, mentioned above, but also an opposite face which, for its part, will have a reflective aspect that can be modulated in color and intensity thanks to this coating. This type of glazing made optically “asymmetrical” advantageously finds application, for example, as glazing for the automobile such as a car roof; from the outside, the observer sees a particularly aesthetic reflective glazing, while on the interior side of the passenger compartment, the desired diffusing effect is maintained.

Another role can be given to the reflective coating: by choosing its type and thickness appropriately, it can be used as the electrically conductive layer of the electrically controllable system.

Many reflective coatings can be advantageously used in the context of the invention. They can be mono-layers or consist of a stack of at least two layers. In general, it is a reflective layer which is associated with at least one layer of dielectric material intended to protect it from chemical or mechanical attack and / or to adjust its optical properties. A coating is usually used in the form of at least one reflective layer disposed between two layers (or layer overlays) of dielectric material of the oxide or nitride type of metal or silicon.

We can choose the reflective layer based on at least one of the metals belonging to the following group: silver Ag, gold Au, copper Cu, aluminum Al, chromium Cr, nickel Ni, iron Fe, tantalum Ta, zirconium Zr, zinc Zn, tin Sn, indium In, rhodium Rh, cadmium Cd or even silicon Si (these metals or metal alloys can also be nitrided).

It can also be a reflective layer based on at least one metallic nitride such as titanium nitride TiN, zirconium nitride ZrN, hafnium nitride HfN.

Reflective layers meeting this definition and particularly preferred in the context of the invention are silver-based layers, in particular incorporated in a stack of the type:<ul id="ul0003" list-style="none" compact="compact"><li>dielectric / silver / dielectric or</li><li>dielectric / silver / dielectric / silver / dielectric,</li></ul> optionally with between the silver layer and at least one of the adjacent dielectric layers thin layers based on partially or fully oxidized metal intended to act as nucleation layers and / or barrier layers against oxidation in particular .

For more details, reference is advantageously made, in particular, to patents EP-506 507, EP-611 213, EP-636 587, EP-638 528, EP-645 352, EP-678 484, EP-709 349, EP -718,250.

Another preferred reflective layer glazing according to the invention meeting this definition is a layer based on Ni-Cr alloy or based on Ni-Cr-Fe alloy of the steel type, optionally nitrided alloys, or based on tantalum . This layer is placed between two layers of oxide or nitride of the Ta type.₂O₅, SnO₂, TiO₂, TiN, as described in particular in patent EP-511,901.

It can also be a TiN-based layer, associated with at least one other oxide layer of the TiO type.₂ or SiO_xVS_y, as described in particular in patents EP-638,527 and EP-650,938.

A description of a silicon-based reflective layer associated with a second oxide layer is also found in patent FR-2 391 173.

As another type of reflective layer, there are also layers based on metal oxide (s) possibly doped, in particular based on titanium oxide, such as the coating of glazing sold under the name "Antelio By Saint-Gobain Vitrage, or based on tin oxide doped with fluorine SnO₂: F or indium oxide doped with ITO tin. For more details, reference may be made, in particular, to patent FR-2 310 977 for the description of the method of obtaining a layer of titanium oxide, or to patents EP-544 577, EP-573 325, EP-648,196 corresponding to PCT application WO 94-25 410 for the description of layer stacks incorporating a layer of SnO₂: F. It may further be noted that if a reflective layer based on titanium oxide is chosen which is at least partially crystallized in anatase or anatase / rutile form, this type of layer also exhibits both photocatalytic and hydrophilicity which give it anti-fogging and / or anti-fouling properties which are particularly advantageous if it is deposited on one of the external faces of the glazing. Advantageously, reference may be made to patent FR 95/10 839 filed on September 15, 1995 for more details.

In fact, once the choice of material for the reflective layer has been made, it is then necessary to optimize its thickness as a function of the desired effect, in particular as a function of the degree of "filtering", of the solar radiation which is required. or the change in optical appearance which is sought.

The invention applies to different types of active glazing, of the electrochemical type or of the photochromic type. As we have seen, these may be glazings with variable light transmission / absorption, in particular with a viologen or electrochromic system, in particular of the type described in the aforementioned patents EP-0 338 876, EP-0 408 427 , EP-0 575 203, EP-0 628 849. It is preferably in the form of a stack of functional layers successively comprising an electrically conductive layer, preferably transparent, an electrochromic layer called cathodic capable of reversibly inserting cations such as H⁺, Li⁺, N / A⁺, Ag⁺, an electrolyte layer, possibly a counter electrode in the form of a second electrochromic layer called anodic also capable of reversibly inserting cations and finally a second electrically conductive layer.

With regard to the nature of the electroconductive layers of the device, there are two possible variants: recourse can be had to materials based on doped metal oxide such as tin oxide doped with fluorine SnO₂: F or indium oxide doped with ITO tin. It is also possible to use layers of metal or of a metallic alloy, for example from Au gold, Ag silver or Al aluminum. The device generally having two electroconductive layers, they can be either both metallic or both based on doped oxide, one based on metal and the other based on doped oxide.

To constitute the layer of cathodic electrochromic material, it is possible to choose a material or a mixture of materials chosen from the group comprising tungsten oxide WO₃, molybdenum oxide MoO₃, vanadium oxide V₂O₅, niobium oxide Nb₂O₅, titanium oxide TiO₂, a “cermet” material (combination of metallic and ceramic material, in particular in the form of metallic particles in a ceramic matrix) such as WO₃/ Au or WO₃/ Ag, a mixture of tungsten and rhenium oxides WO₃/ ReO₃. These materials are particularly suitable in the case of reversible insertion of lithium ions. In the case where the device operates by reversible insertion of protons, the same materials can be used, but hydrated this time.

To constitute the layer of anodic electrochromic material, one can choose a material which corresponds to the formula M_xAT_yU_z, with M a transition metal, A the ion used for reversible insertion, for example an alkali or a proton, and U a chalcogen such as oxygen or sulfur.

It can be, in particular in the case of an insertion of H proton ions⁺, a compound or a mixture of compounds belonging to the group comprising LiNiO_x, IrO_xH_y, IrO_xH_yNOT_z, NiO_x, NiO_xH_yNOT_z, RhO_x, CoO_x, MnO_x. In the case of a reversible insertion of lithium Li ions⁺, we rather choose a compound or a mixture of compounds belonging to the group comprising LiNiO_x, LiMn₂O₄, IrO_x, Li_xIrO_y, NiO_x, CeO_x, TiO_x, CeO_x-TiO_x, RhO_x, CoO_x, CrO_x, MnO_x.

As regards the choice of the electrolyte material, there are in fact of two types as it was mentioned previously.

It may be a layer of aqueous liquid, such as water with sulfuric or phosphoric acid in the case of a reversible insertion of protons, a layer of anhydrous liquid such as propylene carbonate containing a lithium salt in the case of a reversible insertion of lithium ions. It can also be a layer of gel or of polymer, in particular proton-conducting polymers of the solid solution type of polyoxyethylene and POE-H phosphoric acid.₃PO₄ (in this case, the polymer also constitutes an electronic insulator) or also based on a polymer obtained by copolymerization of three precursors comprising two types of grafted trialkoxysilanes and a plasticizer having at least one urea group. As a polymer conducting lithium ions, an ionomer obtained by partial neutralization of polyacrylic acid, or a polymer based on branched polyethylene imine and a lithium salt, can be chosen. For more details on the nature and synthesis of such polymeric products, advantageously refer to the patents cited in the preamble to the present application.

However, it can also be an electrolyte in the form of a solid material, in particular based on metal oxide. According to a variant of the invention, the system is chosen such that it only contains layers of solid material. In the context of the invention, the term “solid material” means any material having the mechanical strength of a solid, in particular any essentially mineral or organic material or any hybrid material, that is to say partially mineral and partially organic, like the materials that can be obtained by sol-gel deposition from organomineral precursors. We then have a so-called “all solid” system configuration which has an advantage in terms of ease of manufacture. In fact, when the system contains an electrolyte in the form of a polymer which does not have the mechanical strength of a solid, for example, this forces in fact to manufacture, in parallel, two "half-cells" each consisting of carrier substrate coated with a first electroconductive layer and then with a second electrochemically active layer, these two half-cells then being assembled by inserting the electrolyte therebetween. With an “all solid” configuration, manufacturing is simplified, since all the layers of the system can be deposited, one after the other, on a single carrier substrate. The electrochromic system / carrier substrate assembly is thus reduced, since it is then possible to be satisfied with a single carrier substrate instead of usually two.

In addition, whether the electrolyte is "solid" or not, it may comprise a layer of an ion-conducting material capable of reversibly inserting the ions but the oxidation state of which is kept essentially constant. It may especially be a material with electrochromic properties, as described in the aforementioned patent FR-96/03799.

The variable light transmission / absorption system of the element according to the invention can therefore be placed either between two rigid substrates, or on a single rigid substrate more particularly in the case of an “all solid” system. The rigid support substrates are preferably made of glass, acrylic polymer, polycarbonate or certain polyurethanes.

Whatever the configuration adopted, provision may also be made to laminate the carrier substrate or at least one of the carrier substrates of the electrochromic system by means of a sheet of assembly polymer of the PVB (polyvinyl butyral), EVA ( ethylene vinyl acetate), PU (polyurethane).

At least one of the carrier substrates can also be associated with another rigid substrate by means of an intermediate gas layer. The glazing then becomes a multiple glazing with reinforced thermal insulation properties, in particular double glazing. This laminated structure can be mounted in insulating double glazing, with for example the sequence glass 1 / reflective coating / sheet of assembly polymer / glass 2 / electrochromic system / glass 3 / interlayer gas slide / glass 4. (This multiple glazing configuration can also be adopted when the electrically controllable system is of the liquid crystal type).

Preferably, the reflective coating is arranged on the face of one of the carrier substrates opposite to that facing the side of the active system (electrochromic) or on one of the faces of one of the other constituent substrates of the glazing. It is thus possible to have glazing presenting the sequence:

glass 1 / reflective coating / assembly polymer sheet / glass 2 / electrochromic system / glass 3. This reflective coating may alternatively be on the face of the glass 2 facing the assembly polymer sheet, or on the exterior face glass 1 if it has sufficient mechanical and chemical durability. This laminated structure can be mounted in insulating double glazing, with, for example, the sequence glass 1 / reflective coating / sheet of assembly polymer / glass 2 / electrochromic system / glass 3 / interlayer gas slide / glass 4.

The glazing according to the invention can also be chosen with variable light diffusion, in particular by incorporating the so-called optical valve or liquid crystal systems which have been previously described. In the case of liquid crystal systems, the nature of the polymer matrix and of the crystals is judiciously chosen so that the ordinary index of the liquid crystals n_o be equal to the index of the polymer n_p.

Whether optical valves or liquid crystal systems, both systems come in the form of a polymer-based composite film. In order to ensure its electrical supply, it is usually placed between two electroconductive layers, in particular transparent layers and of the type of those used for the electrochromic systems previously described.

It should also be noted that the liquid crystal droplets of the polymer-liquid crystal composite may also contain a dye or a mixture of dyes, in particular in the form of dichroic dyes which are dyes having an absorption anisotropy orientable by the liquid crystals.

In addition, the film with its two conductive layers is usually provided on at least one of its faces, and preferably each of them, with a carrier substrate. This is generally transparent. It can be chosen rigid or semi-rigid, for example being made of glass, acrylic polymer of the polymethylmethacrylate PMMA type or of PC polycarbonate. It can also be flexible, in particular made of polyethylene terephthalate PET or based on certain flexible polycarbonates. It is thus possible to have a structure of the PET / ITO / polymer-liquid crystal / ITO / PET composite type, which is in the form of a flexible sheet which is easy to handle. This assembly (composite + electroconductive layers + at least one carrier substrate) can then be laminated to at least one transparent rigid substrate of the glass type using at least one layer of organic assembly polymer of the polyvinyl butyral PVB, ethylene vinyl acetate type. EVA or certain PU polyurethanes.

According to a preferred configuration of this type of glazing with variable light diffusion, the reflective coating according to the invention is arranged on the face of one of the carrier substrates facing the side of the liquid crystal system. However, it can also be arranged on the opposite face, or on one of the faces of one of the other constituent substrates of the glazing. The glazing can thus present the sequence:    glass (1) / reflective coating / assembly polymer sheet / flexible polymer sheet / liquid crystal system / flexible polymer sheet / assembly polymer sheet / glass (2). As in the case of electrochromic glazing, the reflective coating may alternatively be located, in particular, on the outer face of the glass 1.

Whether it is an electrocontrollable system of the electrochromic type or of the liquid crystal type, a double glazing configuration can be chosen such that the substrate (s) carrying the electrocontrollable system is (are) separated from the substrate provided with the reflective coating according to the invention by an interlayer of gas. There is then a glazing of the type: glass 1 / reflective coating / interlayer gas slide / electrically controllable system associated with at least one glass 2.

Whatever the type of electrically controllable glazing envisaged, one may want to give it an additional property of reducing its light and / or energy transmission, with a view to proposing glazing having enhanced anti-solar properties or even improved visual comfort, anti-glare effect or a given colorimetric appearance. In this case, at least one of the glazing substrates can be chosen to absorb light and / or energy, in particular in the form of a substrate tinted in the mass in a more or less pronounced manner. If the reflective coating is used as protection of the electrically controllable system against solar radiation, it is of course preferable to configure the glazing so that the mass-tinted substrate is separated from the substrate in contact with the coating reflecting by at least the electrocontrollable system, for example with a sequence of the type:    clear glass 1 / reflective coating / ... / electrocontrollable system of the liquid crystal type / ... / tinted glass 3, the dotted lines representing at least one material of the rigid substrate, assembly polymer sheet or interlayer gas plate type.

By mounting the glazing in a building or a vehicle so that it is the clear glass which is turned towards the outside, the electrically controllable system in contact with an absorbent glass is prevented from heating up:<ul id="ul0004" list-style="none" compact="compact"><li>□ When the electrocontrollable system is of variable absorption, as is the case with an electrochromic system, it is in fact likely to heat up in strong sunlight by a phenomenon of energy absorption, when it is in the state colored, hence the interest of the reflective coating according to the invention (the same remark applies to photochromes),</li><li>□ When the electrocontrollable system is of the liquid crystal type or when it is a variable absorption system of the electrochromic type which is in the discolored state, it is better to avoid it being in contact with a tinted glass subjected to direct sunlight, to prevent it from heating up on contact, even if it is not itself absorbent.</li></ul>

Glazing tinted in the mass, especially adapted to the building, are for example marketed under the name "Parsol" by the company SAINT-GOBAIN VITRAGE. Other types of glass with reduced energy transmission are also of interest in the context of the present invention:

These are in particular bronze-colored glasses, as described in patents US-4,190,542 and US-4,101,705, or glasses whose composition has been adjusted rather for an automotive glazing application. This is for example glass called TSA⁺ or TSA⁺⁺, including the levels of Fe type coloring oxides₂O₃, FeO and CoO are adjusted in order to have a selectivity defined by the T ratio_L/ T_E at least 1.30, or even 1.40 to 1.50, and a shade in the greens. Advantageously, reference will be made to European patent application EP-A-0 616 883 for more details. The content of the abovementioned coloring oxides in the glass compositions according to the teaching of this patent is summarized below (weight proportions) .

According to a first series: <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Fe₂O₃</entry><entry namest="col2" nameend="col2" align="left">0.55 to 0.62%</entry></row><row><entry namest="col1" nameend="col1" align="left">FeO</entry><entry namest="col2" nameend="col2" align="left">0.1 to 0.16%</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">CoO</entry><entry namest="col2" nameend="col2" align="left">0 at 12 ppm, in particular &lt;12 ppm with in particular the Fe ratio²+ / Fe of the order of 0.19 to 0.25.</entry></row></tbody></tgroup></table></tables>

According to a second series: <tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Fe₂O₃</entry><entry namest="col2" nameend="col2" align="left">0.75 to 0.90%</entry></row><row><entry namest="col1" nameend="col1" align="left">FeO</entry><entry namest="col2" nameend="col2" align="left">0.15 to 0.22%</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">CoO</entry><entry namest="col2" nameend="col2" align="left">0 at 17 ppm, in particular &lt;10 ppm with in particular the Fe ratio²⁺/ Fe of the order of 0.20.</entry></row></tbody></tgroup></table></tables>

They may also be bulk tinted glasses, in particular blue-green glasses such as those described in patent application EP-A-0 644 164, the composition of which is recalled below: <tables id="tabl0003" num="0003"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">SiO₂</entry><entry namest="col2" nameend="col2" align="left">64 at 75%</entry></row><row><entry namest="col1" nameend="col1" align="left">Al₂O₃</entry><entry namest="col2" nameend="col2" align="left">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">B₂O₃</entry><entry namest="col2" nameend="col2" align="left">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">CaO</entry><entry namest="col2" nameend="col2" align="left">2 at 15%</entry></row><row><entry namest="col1" nameend="col1" align="left">MgO</entry><entry namest="col2" nameend="col2" align="left">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">N / A₂O</entry><entry namest="col2" nameend="col2" align="left">9 at 18%</entry></row><row><entry namest="col1" nameend="col1" align="left">K₂O</entry><entry namest="col2" nameend="col2" align="left">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">Fe₂O₃</entry><entry namest="col2" nameend="col2" align="left">0.75 to 1.4%</entry></row><row><entry namest="col1" nameend="col1" align="left">(total iron expressed in this form)</entry><entry namest="col2" nameend="col2" /></row><row><entry namest="col1" nameend="col1" align="left">FeO</entry><entry namest="col2" nameend="col2" align="left">0.25 to 0.32%</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">SO₃</entry><entry namest="col2" nameend="col2" align="left">0.10 to 0.35%</entry></row></tbody></tgroup></table></tables>

They may also be glasses such as those described in the PCT application filed under the number PCT / FR95 / 00828 on June 22, 1995 corresponding to the application FR-A-2 721 599, the composition of which, always in weight percentages, is recalled below: <tables id="tabl0004" num="0004"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">SiO₂</entry><entry namest="col2" nameend="col2" align="left">69 at 75%</entry></row><row><entry namest="col1" nameend="col1" align="left">Al₂O₃</entry><entry namest="col2" nameend="col2" align="left">0 at 3%</entry></row><row><entry namest="col1" nameend="col1" align="left">B₂O₃</entry><entry namest="col2" nameend="col2" align="left">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">CaO</entry><entry namest="col2" nameend="col2" align="left">2 at 10%</entry></row><row><entry namest="col1" nameend="col1" align="left">MgO</entry><entry namest="col2" nameend="col2" align="left">0 at 2%</entry></row><row><entry namest="col1" nameend="col1" align="left">N / A₂O</entry><entry namest="col2" nameend="col2" align="left">9 at 17%</entry></row><row><entry namest="col1" nameend="col1" align="left">K₂O</entry><entry namest="col2" nameend="col2" align="left">0 at 8 %</entry></row><row><entry namest="col1" nameend="col1" align="left">Fe₂O₃ (total iron)</entry><entry namest="col2" nameend="col2" align="left">0.2 to 4%</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Se, CoO, Cr₂O₃, NiO, CuO</entry><entry namest="col2" nameend="col2" align="left">0 0.45%</entry></row></tbody></tgroup></table></tables>    the content of coloring agents other than iron being at least 0.0002% when the content of Fe₂O₃ is equal to or less than 1.5%, this composition being capable of also containing fluorine, oxides of zinc, zirconium, cerium, titanium and less than 4% of barium oxide, the sum of the percentages of the oxides alkaline earth remaining 10% or less.

Still according to the teaching of this patent, it is preferred that the coloring agents other than iron are introduced into the composition of the glasses alone or in combination, according to weight contents which, preferably, remain below the following limits:<ul id="ul0005" list-style="none" compact="compact"><li>Se &lt;0.008%</li><li>CoO &lt;0.04%</li><li>Cr₂O₃ &lt; 0,1 %</li><li>NiO &lt;0.07%</li><li>CuO &lt;0.3%.</li></ul>

It can also be glasses such as those described in PCT application / FR96 / 00394 filed March 14, 1996 and corresponding to the French patent application filed March 16, 1995 under number 95/03858, glasses comprising, expressed in weight percentages, 0.85 to 2% total iron expressed as Fe₂O₃, the FeO content by weight being between 0.21 and 0.40%.

According to this patent, the compositions are, according to a first series, the following: <tables id="tabl0005" num="0005"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">SiO₂</entry><entry namest="col2" nameend="col2" align="left">64 at 75%</entry></row><row><entry namest="col1" nameend="col1" align="left">Al₂O₃</entry><entry namest="col2" nameend="col2" align="left">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">B₂O₃</entry><entry namest="col2" nameend="col2" align="left">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">CaO</entry><entry namest="col2" nameend="col2" align="left">2 at 15%</entry></row><row><entry namest="col1" nameend="col1" align="left">MgO</entry><entry namest="col2" nameend="col2" align="left">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">N / A₂O</entry><entry namest="col2" nameend="col2" align="left">9 at 18%</entry></row><row><entry namest="col1" nameend="col1" align="left">K₂O</entry><entry namest="col2" nameend="col2" align="left">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">Fe₂O₃ (total iron expressed in this form)</entry><entry namest="col2" nameend="col2" align="left">0.85 to 2%</entry></row><row><entry namest="col1" nameend="col1" align="left">FeO</entry><entry namest="col2" nameend="col2" align="left">0.21 to 0.40%</entry></row><row><entry namest="col1" nameend="col1" align="left">CoO, Cr₂O₃, Se, TiO₂, MnO, NiO, CuO</entry><entry namest="col2" nameend="col2" align="left">0 0.04%</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">SO₃</entry><entry namest="col2" nameend="col2" align="left">0.08 to 0.35%</entry></row></tbody></tgroup></table></tables>    and according to a second series, the following: <tables id="tabl0006" num="0006"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">SiO₂</entry><entry namest="col2" nameend="col2" align="left">68 at 75%</entry></row><row><entry namest="col1" nameend="col1" align="left">Al₂O₃</entry><entry namest="col2" nameend="col2" align="left">0 at 3%</entry></row><row><entry namest="col1" nameend="col1" align="left">B₂O₃</entry><entry namest="col2" nameend="col2" align="left">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">CaO</entry><entry namest="col2" nameend="col2" align="left">2 at 10%</entry></row><row><entry namest="col1" nameend="col1" align="left">MgO</entry><entry namest="col2" nameend="col2" align="left">0 at 2%</entry></row><row><entry namest="col1" nameend="col1" align="left">N / A₂O</entry><entry namest="col2" nameend="col2" align="left">9 at 18%</entry></row><row><entry namest="col1" nameend="col1" align="left">K₂O</entry><entry namest="col2" nameend="col2" align="left">0 at 8 %</entry></row><row><entry namest="col1" nameend="col1" align="left">Fe₂O₃(total iron expressed in this form)</entry><entry namest="col2" nameend="col2" align="left">0.95 to 2%</entry></row><row><entry namest="col1" nameend="col1" align="left">CoO, Cr₂O₃, Se, TiO₂, MnO, NiO, CuO</entry><entry namest="col2" nameend="col2" align="left">0 0.04%</entry></row><row><entry namest="col1" nameend="col1" align="left">FeO</entry><entry namest="col2" nameend="col2" align="left">0.29 to 0.40%</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">SO₃</entry><entry namest="col2" nameend="col2" align="left">0.08 to 0.35%</entry></row></tbody></tgroup></table></tables>

It can also be a tinted glass in accordance with the teaching of patent EP-0 452 207, the composition of which is generally as follows, in weight proportions: <tables id="tabl0007" num="0007"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">SiO₂</entry><entry namest="col2" nameend="col2" align="right">64 at 75%</entry></row><row><entry namest="col1" nameend="col1" align="left">Al₂O₃</entry><entry namest="col2" nameend="col2" align="right">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">B₂O₃</entry><entry namest="col2" nameend="col2" align="right">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">CaO</entry><entry namest="col2" nameend="col2" align="right">5 at 15%</entry></row><row><entry namest="col1" nameend="col1" align="left">MgO</entry><entry namest="col2" nameend="col2" align="right">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">N / A₂O</entry><entry namest="col2" nameend="col2" align="right">10 at 18%</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">K₂O</entry><entry namest="col2" nameend="col2" align="right">0 at 5 %</entry></row></tbody></tgroup></table></tables> the sum of the alkaline earth oxides being between 6 and 16% and those of the alkaline oxides between 10 and 20% and comprising as coloring agents: <tables id="tabl0008" num="0008"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Fe₂O₃ (total iron)</entry><entry namest="col2" nameend="col2" align="right">1.4 to 4%</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">CoO</entry><entry namest="col2" nameend="col2" align="right">0 0.05%</entry></row></tbody></tgroup></table></tables> with CoO&gt; around 0.02% when Fe₂O₃ &lt;about 2%, and possibly selenium and chromium oxide, the sum CoO + Se + Cr₂O₃ up to 0.24%, this glass having a global light transmission factor under illuminant A (TL_AT) equal to or less than about 20% and an overall energy transmission factor (T_E) less than or equal to about 12% for a thickness of 3.85 mm.

Mention may also be made of tinted glasses, the composition of which corresponds to that defined in patent WO 93/07095, in the following manner, always in weight proportions: <tables id="tabl0009" num="0009"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">SiO₂</entry><entry namest="col2" nameend="col2" align="right">64 at 75%</entry></row><row><entry namest="col1" nameend="col1" align="left">Al₂O₃</entry><entry namest="col2" nameend="col2" align="right">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">B₂O₃</entry><entry namest="col2" nameend="col2" align="right">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">CaO</entry><entry namest="col2" nameend="col2" align="right">5 at 15%</entry></row><row><entry namest="col1" nameend="col1" align="left">MgO</entry><entry namest="col2" nameend="col2" align="right">0 at 5 %</entry></row><row><entry namest="col1" nameend="col1" align="left">N / A₂O</entry><entry namest="col2" nameend="col2" align="right">10 at 18%</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">K₂O</entry><entry namest="col2" nameend="col2" align="right">0 at 5 %</entry></row></tbody></tgroup></table></tables> and, as coloring agents: <tables id="tabl0010" num="0010"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Fe₂O₃ (total iron)</entry><entry namest="col2" nameend="col2" align="right">0.45 to 2.5%</entry></row><row><entry namest="col1" nameend="col1" align="left">CoO</entry><entry namest="col2" nameend="col2" align="right">0.001 to 0.02%</entry></row><row><entry namest="col1" nameend="col1" align="left">Se</entry><entry namest="col2" nameend="col2" align="right">0 0.0025%</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Cr₂O₃</entry><entry namest="col2" nameend="col2" align="right">0 0.1%</entry></row></tbody></tgroup></table></tables> such a glass having an overall energy transmission factor (T_E) lower than the light transmission factor under illuminant A (TL_AT), factor T_E being between 10 and 48% and the TL factor_AT between 20 and 60% for a thickness of 3.85 millimeters.

All these types of tinted glass compositions can therefore be advantageously chosen so that the glazings have energy transmission values ​​between 6 and 70%, in particular between 20 and 60% and light transmission values ​​between 10 and 85 %.

The subject of the invention is also the use of the glazings previously described as glazing for the building, in particular as exterior glazing, glazing for interior partitions or glazed doors, and as glazing fitted to means of transport, in particular automotive glazing such as car roofs, railway glazing or aircraft glazing, in particular as windshields or anti-solar windscreen strips.

These glazings can have a “monolithic” structure, that is to say with a single rigid substrate, or a plurality of rigid substrates, have a laminated and / or multiple glazing structure, or even a so-called asymmetric glazing structure with outer plastic layer, in particular based on polyurethane with energy absorption properties, structure notably described in patents EP-191 666, EP-190953, EP-241 337, EP-344045, EP-402 212, EP-430 769 and EP-673,757.

It is also possible to use the glazings of the invention as mirrors, by adjusting the nature and the thickness of the reflective coating, and more particularly as one-way mirrors which can also be described as “spy mirrors”: if we replace the tain of the mirror by a variable light diffusion system of the liquid crystal type, not only an observer in a room can observe the interior of an adjacent room without a person who is in this room adjacent to it notices, but in addition the observer can, if he wishes, prevent a person entering the room where he is to realize that it is a two-way mirror, by making diffusing glazing.

Other details and advantageous characteristics of the invention emerge from the description given below with reference to the appended drawings which represent:<ul id="ul0006" list-style="none" compact="compact"><li>□ <b>figure 1</b> : electrochromic glazing with a laminated sectional structure,</li><li>□ <b>figure 2</b> : electrochromic glazing according to FIG. 1 mounted in double glazing,</li><li>□ <b>figure 3</b> : electrochromic glazing mounted in double glazing according to another configuration.</li><li>□ <b>figure 4</b> : sectional liquid crystal glazing.</li><li>□ <b>figure 5</b> : liquid crystal glazing mounted in double glazing.</li></ul>

These figures are extremely schematic and do not respect the proportions between the different elements represented, this in order to facilitate reading. Are not shown, in particular, all the electrical connections which are known per se.

The rigid substrates used for all of the following examples are 4 mm thick soda-lime silica glass substrates. (their thickness can in fact be chosen in particular in the range of 3 to 6 mm).

Subsequently, the so-called “clear” glass substrates are glasses sold by SAINT-GOBAIN VITRAGE under the name Planilux. The so-called “tinted” glass substrates are glasses having, at about 4 mm thickness, values ​​of T_L 35% and T_E 18.7% under illuminant D₆₅. Their chemical composition is defined by that of Example 2 of the aforementioned patent WO 93/07095, which comprises, in weight ratio, the following oxides acting on the coloring:<tables id="tabl0011" num="0011"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Fe₂O₃ (total iron)</entry><entry namest="col2" nameend="col2" align="right">1,65 %</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Co</entry><entry namest="col2" nameend="col2" align="right">0,0110 %</entry></row></tbody></tgroup></table></tables>

Examples 1 to 4 relate to Figures 1 to 3 and relate to electrochromic glazing.

<u>EXAMPLE 1</u>

FIG. 1 represents an electrochromic glazing with a laminated structure with three glasses, in a configuration suitable for example for use as a car roof: two clear glasses 2,3 are represented, between which is placed an electrochromic system 4 consisting of stacking of the following functional layers (stacking in accordance with the teaching of European patent EP-0 628 849):<ul id="ul0007" list-style="none" compact="compact"><li>□ a first electrically conductive layer of SnO₂: F of 300 nm,</li><li>□ a first layer of anodic electrochromic material in hydrated iridium oxide of 55 nm, (it could be replaced by a layer of hydrated nickel oxide),</li><li>□ a layer of hydrated tantalum oxide Ta₂O₅.H_x 70 nm protective function,</li><li>□ an electrolyte layer in solid solution of polyoxyethylene with POE-H phosphoric acid₃PO₄ 100 micrometers,</li><li>□ a second layer of cathodic electrochromic material based on tungsten oxide of 350 nm,</li><li>□ a second layer of SnO₂: F of 300 nm.</li></ul>

The glass 2 + electrochromic system 4 + glass 3 assembly is then laminated to a third clear glass 1 by means of a sheet 5 of organic assembly polymer of the PVB type with a thickness of 0.5 to 1 mm, especially 0.75mm. On the face of the glass 1 turned towards the side of the PVB sheet 5 is disposed a reflective coating 6 consisting of the following stack of thin layers, starting from the glass 1:<ul id="ul0008" list-style="none" compact="compact"><li>□ a layer of SnO₂ 41 nm,</li><li>□ a first layer of 18 nm silver,</li><li>□ a layer of SnO₂ 74 nm,</li><li>□ a second layer of silver of 12 nm,</li><li>□ a layer of SnO₂ 33 nm.</li></ul>

In addition, on each side of each of the silver layers, there is a thin metallic layer based on Ni-Cr, of approximately 0.5 to 1.5 nm.

This type of stack is, in known manner, obtained by a sputtering technique assisted by a magnetic field, the Ni-Cr layers making it possible to protect the silver layers from oxidation during the deposition of the SnO layers.₂ by reactive spraying in the presence of oxygen, by oxidizing partially or completely in their place.

For other types of equivalent stacks of the type (dielectric / silver)_not, with n ≥ 1, advantageously refer to the patents cited in the preamble. (Thus, it is possible to use dielectric materials other than tin oxide, for example TiO₂, ZnO, Nb, Ta₂O₅, Yes₃NOT₄, ... or a superposition of dielectric materials like SnO₂/ Nb₂O₅, Nb₂O₅/ ZnO, SnO₂/Your₂O₅, ... Similarly, the barrier layers of Ni-Cr are optional, and can be substituted, for example, by metal layers of the Ti, Ta, Nb, Zn, Sn, ... type.

Such glazing is preferably mounted so that the glass 1 faces outward. Thus, the electrochromic system 4 is protected from solar radiation both by the sheet 4 of PVB, which, preferably, contains agents filtering ultraviolet, and especially by the reflective coating 5 according to the invention. This coating, which uses two reflective layers, is particularly effective in its role of solar filter. This is all the more important when this glazing is used as a car roof, that is to say in a horizontal position which is a configuration which particularly demands the electrochromic system in terms of temperature resistance, or even in position inclined to the vertical, if you want to use it as canopy glazing, velux type roof window, ...

<u>EXAMPLE 2</u>

It corresponds to the configuration of electrochromic glazing shown in Figure 2: we find the glasses 1, 2, 3 of Figure 1 as well as the same sheet of PVB 5, the same reflective coating 6 and the same electrochromic system 4. This set tri-glass was mounted in double glazing using a fourth clear glass 7 by means of an argon blade 8 12 mm thick, using assembly means known from field of double glazing and not shown.

On the face of the glass 7 facing the argon blade 8, is disposed a coating 9 with low-emissivity properties, of the type of those which are fitted to the glazing sold under the name of Planitherm by SAINT-GOBAIN VITRAGE, ie l '' next stack:<ul id="ul0009" list-style="none" compact="compact"><li>□ a 40 nm layer of tin oxide,</li><li>□ a 9 nm silver layer,</li><li>□ a 40 nm layer of tin oxide,</li></ul>    with, as for the stack 6 previously described, the presence of two thin layers of Ni-Cr of 0.5 to 1.5 nm intended to protect the silver from oxidation. This type of double glazing can be used in particular as exterior glazing fitted to building facades (as described in patent EP-0 575 207), or in canopies, verandas or roof windows.

Two advantages stem from this type of structure: from an aesthetic point of view, when all the glazing on the facade is put in the colored state, the presence of the reflective coating 6 gives the facade, on the outside, an aesthetic reflective appearance , and which we may prefer to the relatively dark and absorbent appearance that these glazings seen from the outside would have without the reflective coating in question.

From the point of view of thermal protection, the assembly according to Figures 1 and 2 effectively protects the electrochromic glazing against excessive heating.

The second coating of the low-emissivity type 9 based on a silver layer (which could alternatively be in SnO₂: F for example) does not contribute to the protective effect vis-à-vis the electrochromic system. It is optional, but its presence makes it possible to improve the thermal insulation properties specific to a double glazing structure, in particular by reducing its coefficient K (the coefficient K represents the heat flow which crosses 1 m² of wall for a temperature difference of 1 degree between the inside and the outside of the room).

Table 1 below groups together for examples 1 and 2, with reference to the illuminant D₆₅, the following spectrophotometric values ​​in the minimum colored state EC and in the maximum discolored state ED: the light transmission T_L, the energy transmission T_E, the energy absorption AE, in percentages, the coefficient K in Wm^-2. ° K^-1, the solar factor FS defined by the ratio between the total energy entering the room through the glazing and the incident solar energy, without unit.

Also shown in the table is an example 2bis, corresponding to the configuration of example 2 but devoid of the low-emissivity coating 9, and an example 2ter which, for comparison, also corresponds to the configuration of example 2 but devoid of of the reflective coating 6 according to the invention.<tables id="tabl0012" num="0012"><img file="EP0825478A1_D0001.tif" /></tables>

From this table, it can be seen that the removal of the low-emissive stack 9 in Example 2bis compared with Example 2 allows the minimum value of T to be increased by 3%._L glazing without affecting its energy absorption, but somewhat to the detriment of the K coefficient and the solar factor FS. The choice of one or other of the configurations will depend on the intended application, the climate ...

It may also be noted, from the comparison of examples 2 and 2b, that the presence of the reflective coating of example 2 does not penalize the contrast and that very slightly the light transmission of the glazing, but that, on the other hand, it makes it possible to reduce very significantly its energy absorption.

Furthermore, for each of the configurations of Examples 1 and 2, the maximum surface temperature of the glazing was measured in comparison with identical glazing but lacking the protective coating 6, when these are subjected, in a horizontal position, to sunshine corresponding to an energy of 850 W / m², it can be seen that the maximum temperature of the glazing units according to Examples 1 and 2, in the colored state, is at most 69 ° C., while it is 83 ° C. in the absence of coating 5. This difference 14 ° C is far from negligible, because it increases the life of electrochromic glazing.

Note also that if we choose an electrochromic system 4 "all solid", we can have a double glazing structure "lighter" than that shown in Figure 2, in particular of the glass type 1 / electrochromic system / gas slide / glass 2, the reflective coating can then be placed on the outside of the glass 1, if it has the required durability, for example if it is based on TiO₂, similar to the coating with which the glazing sold under the name of Antélio by SAINT-GOBAIN VITRAGE is fitted.

<u>EXAMPLE 3</u>

It corresponds to the configuration of FIG. 3 which represents an electrochromic double glazing having the same components (but devoid of the low-emissive stack 9) as that of FIG. 2, assembled differently.

Here, the glass 1, that is to say the one intended to be turned towards the outside once the glazing has been mounted, only carries the reflective coating 6 and is not laminated. There is therefore the electrochromic system 4 between the glasses 7 and 3, the glass 3 being laminated to the glass 2 by means of the PVB sheet 5. The set of glasses 2, 3 and 7 is then mounted in double glazing by an argon blade 8 with the glass 1 carrying the reflective coating 6 on its face facing the argon blade.

Many other variants of electrochromic glazing according to the invention are possible, as already mentioned above. Thus we can have the configuration of Example 3, but by removing the glass 2 and the PVB sheet 5, that is to say by avoiding leafing through the glass 3.

If an “all solid” electrochromic system 4 is adopted, for example having the following stack:<ul id="ul0010" list-style="dash" compact="compact"><li>an electrically conductive layer of SnO_{2 :} F of 300 nm,</li><li>a layer of cathodic electrochromic material in tungsten oxide of 380 nm,</li><li>a two-layer electrolyte decomposing into a layer of hydrated tantalum oxide Ta₂O₅. nH₂18 nm O and a layer of hydrated tungsten oxide WO₃.nH₂O of 200 nm,</li><li>a layer of anodic electrochromic material based on hydrated iridium oxide H_xIrO_y 45 nm, (it can be replaced by hydrated nickel oxide),</li><li>a 200 nm ITO electrically conductive layer,</li></ul>    we can have a double glazing structure with only two glasses, of the glass type 1 / reflective coating 6 / gas slide 8 / electrochromic system 4 / glass 2.

The following examples 4 and 6 relate to a liquid crystal glazing.

<u>EXAMPLE 4</u>

This example relates to a liquid crystal glazing as shown in Figure 4:

It comprises two clear glasses 10, 11, between which are arranged two sheets of PVB of 0.75 mm 12, 13, surrounding two sheets of polyethylene terephthalate PET 14, 15 of 175 micrometers thick between which is the liquid crystal system 16 of 25 micrometers thick. In fact, the production is done in two stages, first the production of the PET / ITO / polymer composite - liquid crystal / ITO / PET film, which film is then laminated to glasses 10 and 11 using the sheets. 12 and 13.

In addition, between the glass 11 and the PVB sheet 13, there is a reflective coating 17 similar to the reflective coating 5 with two silver layers, but with different thicknesses of silver layers, the stack 17 is as follows , (in accordance with the teaching of European patent EP-638 528):<ul id="ul0011" list-style="none" compact="compact"><li>□ a layer of SnO₂ 34.4 nm,</li><li>□ a first layer of silver of 12 nm,</li><li>□ a layer of SnO₂ 98 nm,</li><li>□ a second layer of 18 nm silver,</li><li>□ a layer of SnO₂ 35 nm,</li></ul>

In addition, on each side of each of the silver layers, there is a thin metallic layer of Nb of approximately 1.5 nm.

The liquid crystal system 16 comprises two transparent conductive layers of lTO with resistivity of 100 ohms per square deposited on each of the PET sheets, between which there is a polymer-liquid crystal composite consisting of a polymer, in which have been previously dispersed nematic liquid crystal micro-drops, which constitutes the liquid crystal emulsion. The liquid crystal system used is of the type described in patents WO-90/03593, US-5 206 747 and EP-0 409 442 and marketed by SAINT-GOBAIN VITRAGE under the name Priva-lite. It operates at 110V / 50Hz: supplied with electricity, it is transparent. It becomes diffusing when the power supply is cut off. Note that if dichroic dyes are introduced into the liquid crystal droplets, the coating 17 serves, at least partially, as an ultraviolet filter protecting them. This ultraviolet effect can be enhanced by using a glass, on the outside, with an anti-ultraviolet filter effect.

<u>EXAMPLE 5</u>

This example 5 also relates to a liquid crystal glazing of the type represented in FIG. 4, with the same system 14, 15, 16 with PET / ITO liquid crystal / polymer composite - liquid crystal / PET / ITO, and the same reflective coating 17 By cons here, the glass 11 is only 2 mm thick, and the second glass 10 is a tinted glass in the mass as defined above 4 mm thick. In addition, the PVB sheets 12, 13 are replaced by 0.65 mm sheets made of polyurethane.

Tables 3 and 4 below group, for Examples 4 and 5 respectively, the following photometric values ​​always according to the illuminant D₆₅ and with reference to ISO 9050: T_L light transmission in%, lambda dom (T) the dominant wavelength in transmission in nm, pe (T) the color purity in transmission in%, T_E the energy transmission in%, the light reflection "side" substrate 11 R_L, as well as its dominant wavelength and its lambda dom purity (R_L) and pe (R_L), the light reflection "side" substrate 10 R '_L, as well as its dominant wavelength and its lambda dom purity (R '_L) and pe (R '_L). Also given are the solar factors FS already explained, as well as the energy absorption values ​​AE and blur FI, defined by the light scattering rate in%. All these data are indicated in the “ON” state, that is to say in the transparent state when the glazing is supplied with electricity, and in the “OFF” state, that is to say when the glazing is no longer supplied with electricity and it is diffusing.<tables id="tabl0013" num="0013"><img file="EP0825478A1_D0002.tif" /></tables>

By way of comparison, the spectrophotometric values ​​of a glazing unit of configuration identical to that of the glazing unit of Example 4, but lacking the reflective coating 17 according to the invention, were measured: such glazing has a value of R_L identical to that of R '_L and equal to 18.4% in the "ON" state and 16.5% in the "OFF" state. Likewise, the dominant wavelengths of the references R_L and R '_L are identical and equal to 491 nm, whether the glazing is in the "OFF" state or in the "ON" state. Purity values ​​associated with R reflections_L and R '_L are also identical, and equal to 5.2% whether the glazing is in the "OFF" state or in the "ON" state. Its solar factor FS is 67 in the "ON" state and 65 in the "OFF" state. Its light transmission is 73.5% in the “ON” state and 70.8% in the “OFF” state, associated with a dominant wavelength always equal to 569 nm and a purity always equal to 4 , 3-4.4%.<tables id="tabl0014" num="0014"><img file="EP0825478A1_D0003.tif" /></tables>

From these data can be drawn the following conclusions: one can "adjust" the level of T_L and of T_E in particular by the choice of substrates, glassmakers, clear or tinted. The reflective coating 17 forms a thermal screen, if necessary, vis-à-vis the liquid crystal system. Above all, it makes it possible here to obtain the aspects in reflection on the exterior (glass 11) and interior (glass 10) sides which are different, with for example almost 10% difference between the values ​​of R_L and R '_L, and a purity of coloring in external reflection more than twice as high as in internal reflection: we have a clear reflective effect, with a strong color in blues or blue-green when we look at the glazing from the outside, effect which is much less noticeable when you look at the glazing from the inside. We have been able to verify that, in the absence of a reflective coating, the glazing has absolutely identical interior and exterior reflection aspects, the appearance of the glazing in the "ON" state being white and milky on each side.

Finally, from Table 4, it can be seen that the use of tinted glass makes it possible to reduce the internal reflection value R '_L.

It is therefore possible with this type of glazing to modulate its light diffusion, so that a room or a passenger compartment is sheltered from outside view. But in addition, the outside observer will see the reflective glazing in a pleasant shade, whether it is in a diffusing state or not, an aesthetic exterior appearance which is quite sought after at present.

The invention thus makes it possible to adjust the appearance in external reflection of a liquid crystal glazing colorimetrically, with particular interest when this type of glazing is fitted to vehicles: it is then possible to adjust the appearance of the glazing seen from the exterior depending on the color of the body for example.

<u>EXAMPLE 6</u>

This example corresponds to FIG. 5, which represents a liquid crystal glazing of the type of that of FIG. 4, this time mounted in double glazing: we find the laminated structure glass 10 / PVB 12 / PET 14 / liquid crystal system 16 / PET 15 / PVB 13 / glass 11, structure which is laminated to a third clear glass 18 by means of an argon blade 19 and carrying, on the side of its face facing the argon blade, the coating reflective 17. It is the glass 18 which is intended to be the glass facing outwards once the glazing has been mounted.

Furthermore, the glazings described in all of these examples can be functionalized, for example by presenting on the external face (s), an anti-fouling coating, for example made of TiO₂ at least partially crystallized, as mentioned above, or a hydrophobic anti-rain coating based on fluorinated silane polymer.