Glazing panel

[0001] The invention relates to the field of glazing units comprising a glass substrate provided on at least one of its surfaces with a packet of thin layers.

[0002] In view of environmental protection and the concern for saving energy, flats are now equipped with multiple glazing units, double or even triple, often containing low-emissivity layers designed to limit heat transfer from outside the apartment. However, these glazing units with a very low heat transfer coefficient are exposed to the appearance of condensed water on the outer surface in the form of fog or frost. In the atmosphere created during the night, the heat exchange by radiation with the atmosphere causes a decrease in temperature, which is no longer sufficiently compensated by the heat supply coming from the interior of the apartment. When the outside surface temperature of the glazing unit passes below the dew point, water condenses on said surface limiting morning visibility through the glazing unit, sometimes during a few hours.

[0003] It is known that to solve this problem, a low emissivity layer, e.g. a transparent electrically conductive oxide (TCO) layer, is placed on the surface 1 of the glazing unit (outer surface) to reduce radiation exchange with the atmosphere. Application WO 2007/115796 recommends, for example, the use of a packet comprising a TCO layer, a blocking layer and finally a photocatalytic layer.

[0004] This solution - if it allows the actual solution of a large part of the problems of water condensation - is not without its drawbacks. If the thickness of the layers is not optimal, this solution significantly reduces the total solar energy transmission coefficient of the glazing unit. The coefficient of total solar energy transmittance corresponds to the part of solar energy passed through the glazing unit towards the interior of the apartment by direct penetration through the glazing unit and by re-emission of radiation absorbed by the glazing unit towards the interior. Thus, it is important - especially in winter or in countries with a cold climate - the possibility of maximizing solar heat input through the glazing unit to reduce heating costs.

[0005] The object of the invention is to overcome these drawbacks by proposing a glazing unit that can reduce or even eliminate the appearance of condensation on the external surface (fog or frost), at the same time as little as possible by adversely altering the solar total transmittance factor, and so heat transfers towards the interior of the apartment.

[0006] In view of the above, the invention relates to a glazing unit comprising a glass substrate provided, on one of its surfaces, intended to form the surface 1 of said glazing unit in the position of use, with a thin layer packet comprising - starting from said substrate - a layer of transparent electrically conductive oxide, an intermediate layer with a refractive index ranging from 1.40 to 1.55 and an optical thickness Y, and a photocatalytic layer whose optical thickness X is a maximum of 50 nm, said optical thicknesses X and Y expressed in nanometers are such that:

Iio.e ^ <y <I35._e-°’^O18X.

[0007] By "surface 1" of the glazing unit is meant - as is customary in the art - the outer surface of the glazing unit that is intended to be placed in contact with the outside of the apartment. The surfaces of the glazing unit are marked with numbers starting from the outside, so that surface 2 is the surface opposite to surface 1, in other words the second surface of the same glass pane. In a multilayer glazing unit containing two or more glass panes, surface 3 is the surface of the second glass pane of the glazing unit facing surface 2, surface 4 is the surface opposite the surface 3 etc.

[0008] Refractive indexes are measured, for example, by ellipsometry at 550 nm. The optical thickness of a layer refers to the product with the physical (also called geometric) thickness of the layer and its refractive index.

[0009] The glazing unit according to the invention is preferably a multiple glazing unit, especially a double or triple glazing, and even containing more layers, for example quadruple. These glazing units actually have a low heat transfer coefficient and are most susceptible to condensation. A double glazing unit usually consists of two glass panes opposite each other and introduced with a gas filling, for example air, argon, xenon or also krypton. On the periphery of the glazing unit - between the glass panes 3, a spacer is usually placed in the form of a metal profile, e.g. made of aluminum, connected to the glass panes by means of glue, the rim of the glazing unit being sealed with a putty, e.g. silicone, polysulphide or polyurethane to prevent any penetration into the moisture gas filling. To limit moisture, a molecular sieve is often placed in the spacer. The triple glazing unit is formed in the same way, except that the number of glass panes is three.

[0010] When the glazing assembly according to the invention is a triple glazing assembly, at least one other surface selected from surfaces 2 to 5 is preferably covered with a low emissivity package. In particular, they can be thin layer packages containing at least one silver layer, with the silver layer or each silver layer being placed between the dielectric layers. Low emissivity is usually understood to mean a maximum of 0.1, especially 0.05. Preferably, this packet covers two other surfaces, especially surfaces 2 and 5. Possible but less preferred - are also other configurations: surfaces 2 and 3, 2 and 4, 3 and 4, 4 and 5, surfaces 2, 3 and 4 , surfaces 2, 3 and 5, surfaces 2, 4 and 5, surfaces 2, 3, 4 and 5. Other types of packages can be placed on the surfaces of the glazing unit, for example anti-glare packages, on surfaces 2, 3, 4, 5 or 6 .

[0011] When the glazing assembly according to the invention is a double glazing assembly, the surface 2 is preferably covered with a low emissivity package, especially of the type just described. Alternatively, surface 2 can be covered with a package that allows control of sunlight, which is not, however, advantageous because such a package leads to a reduction of the total solar energy transmission coefficient.

[0012] The glazing assembly according to the invention can be used like any type of glazing assembly. It can be included in the facade, roof, porch. It can be set vertically or inclined.

[0013] The glass substrate is preferably transparent and colorless (thus it is transparent or extra transparent glass). It may be tinted, for example, blue, green, gray, brown, but this embodiment is not preferred because it has a negative effect on the total solar energy transmittance factor. The glass is preferably of the silico-soda-lime type, but it can also be borosilicate or aluminum borosilicate type glass. The substrate thickness is usually in the range from 0.5 mm to 19 mm, preferably from 0.7 to 9 mm, especially from 2 to 8 mm, in fact from 4 to 6 mm. The same applies, where applicable, to other glass panes of a multilayer glazing unit.

[0014] The glass substrate is preferably of the float type, that is, it could be obtained by the method of pouring molten glass onto a molten tin bath (float bath). In this case, the packet can be deposited on both the "tin" surface and the "atmosphere" surface of the substrate. By "atmosphere" and "tin" are meant surfaces of the substrate that have been in contact with the atmosphere in the float bath and in contact with molten tin, respectively. The tin surface contains a small amount of tin surface that has been dispersed in the glass structure.

[0015] At least one glass pane, including the glass pane provided with the package, which is the heart of the invention, can be toughened or hardened to give it better mechanical strength. As will be described below, thermal quenching can also be used to improve the emissivity or photocatalytic properties of the layers. In order to improve the acoustic properties or burglary resistance of the glazing assembly according to the invention, at least one glass pane of the glazing assembly can be combined with another pane by means of an additional polymer pane, such as poly (vinyl butyral) (PVB) or polyurethane (PU).

[0016] The transparent electrically conductive oxide layer is preferably a fluorine doped tin oxide layer (SnO2: F) or a mixed tin and indium oxide (ITO) layer. Other layers are possible, among them thin layers based on mixed indium and zinc oxides (called "IZO"), based on gallium or aluminum doped zinc oxide, based on niobium doped titanium oxide, based on cadmium or zinc, based on tin oxide antimony doped. For aluminum doped zinc oxide, the degree of doping (i.e., the weight of alumina relative to the total weight) is preferably less than 3%. In the case of gallium, the degree of doping may be higher, usually in the range of 5 to 6%. In the case of ITO, the atomic percentage of Sn is preferably in the range of 5 to 70%, especially 10 to 60%. In the case of a fluorine-doped tin oxide layer, the fluorine atomic percentage is preferably a maximum of 5%, usually 1 to 2%.

[0017] These layers have the good climatic resistance necessary when the packet is placed on the surface 1 of the glazing unit, which is not the case with other low-emission layers, such as silver layers. The latter must necessarily be placed on the inner surface of the multilayer glazing unit.

[0018] ITO is particularly preferred, especially when compared to SnO2: F. Due to the higher conductivity, its thickness may be smaller to achieve the same level of emissivity, which allows you to minimize the loss of the factor of total solar energy transmittance. These layers - deposited easily by means of a sputtering method, especially aided by a magnetic field, called the "magnetron process" - are characterized by less roughness, and thus less soiling. During the manufacture, handling and cleaning of the glazing units, the more rough layers tend to retain various deposits which are particularly difficult to remove.

[0019] One of the advantages of fluorine doped tin oxide is, however, its ease of deposition by chemical vapor deposition (CVD), which - unlike the sputtering method - does not require further heat treatment and can be carried out on a flat glass production line by float.

[0020] The thickness of the TCO layer is set - depending on the type of layer - so as to achieve the required emissivity, which depends on the desired anti-condensation parameters. The emissivity of the TCO layer is preferably less than or equal to 0.4, especially 0.3. In the case of ITO layers, the geometric thickness will usually be at least 40 nm, even 50 nm, indeed 70 nm, and often a maximum of 150 nm or 200 nm. For fluorine doped tin oxide layers, the geometric thickness will usually be at least 120 nm, in fact 200 nm, and often a maximum of 500 nm.

[0021] When the glazing assembly is intended to be placed in an upright position, the emissivity is preferably maximum 0.4, in fact 0.3. In the case of fluorine doped tin oxide, this usually requires geometrical thicknesses of at least 120 nm, in fact 200 nm. In the case of ITO, the geometric thickness will usually be at least 40 nm, in fact 50 nm, and often a maximum of 150 nm.

[0022] When the glazing assembly is intended to be positioned in an inclined position, for example in applications such as roofs, the emissivity is preferably a maximum of 0.3, even 0.2, in fact 0.18. The geometrical thicknesses of fluorine doped tin oxide will preferably be at least 300 nm and the ITO geometrical thicknesses at least 60 nm, in fact 70 or 100 nm, and often a maximum of 200 nm.

[0023] By "emissivity" is meant the normal emissivity at 283 K within the meaning of EN 12898.

[0024] The refractive index of the layer of transparent electrically conductive oxide is preferably in the range of 1.7 to 2.5.

[0025] In order to optimize the operation of the invention, the refractive index of the intermediate layer is preferably a maximum of 1.50, in fact 1.48.

[0026] The intermediate layer is preferably based on silica and even formed of silica. It is understood that the silica may be doped or may not be stoichiometric. As examples, silica can be doped with aluminum or boron atoms to facilitate its deposition by sputtering methods. In the case of chemical vapor deposition (CVD), silica may be doped with boron or phosphorus atoms that accelerate deposition. Silica may also be doped with carbon or nitrogen atoms in contents small enough that the refractive index of the layer remains within the said ranges. This intermediate layer also has the advantage of protecting the TCO layer, providing it with better climate resistance as well as better hardening strength. In the case of TCO based on fluorine doped tin oxide, the intermediate layer also has the advantage of smoothing the surface, with reduced abrasion.

[0027] The photocatalytic layer is preferably based on titanium oxide, especially a titanium oxide layer, in particular the refractive index of which is in the range from 2.0 to 2.5. The titanium oxide is preferably at least partially crystallized in the form of anatase, which is the most active phase from the point of view of photocatalysis. Mixtures of the anatase and rutile phases are also very active. The titanium dioxide can optionally be doped with a metal ion, for example a transition metal ion or nitrogen, carbon, fluorine atoms ... Titanium dioxide can also be substoichiometric or superstoichiometric. While titanium oxide is definitely preferred, other photocatalytic oxides can also be used, including SrTiO3, ZnO, SiC, GaP, CdS, CdSe, MoS3, SnO2, ZnO, WO3, Fe2O3, Bi2O3, Nb2O5, KTaO3, BiVO4, Bi2WO6.

[0028] In the glazing assembly according to the invention, the entire surface of the photocatalytic layer, especially based on titanium oxide, is preferably in contact with the outer part so that its self-cleaning function can be fully utilized. However, it may be interesting to cover the photocatalytic layer, especially of titanium dioxide, with a thin hydrophilic layer, especially on the basis of silica, in order to improve the hydrophilicity over time.

[0029] The optical thickness X of the photocatalytic layer, especially based on titanium oxide, is preferably maximum 40 nm, especially 30 nm. Its geometric thickness is preferably maximum 20 nm, in fact 15 nm or moreover 10 nm, and is preferably greater than or equal to 5 nm. Very thin layers - although less active in terms of photocatalytic - have good self-cleaning properties, protecting against dirt deposition and fogging. Even for very thin layers, photocatalytic titanium oxide actually has the characteristic that when it is exposed to sunlight, it becomes extremely hydrophilic with water contact angles less than 5 °, indeed 1 °, which allows easier water drainage, while removing impurities deposited on the surface of the layer. In addition, thicker layers have a greater reflection of light, which reduces the total solar energy transmission coefficient.

[0030] According to a possible embodiment, no layer is placed between the transparent electrically conductive layer and the intermediate layer and / or between the intermediate layer and the photocatalytic layer. Alternatively, a protective layer may be placed between the TCO layer, especially when it is ITO, and the intermediate layer. This layer, whose thickness is preferably maximum 10 nm, especially 5 nm, in particular 2 nm, allows the protection of TCO, in particular ITO, during the deposition of the intermediate layer, especially when the deposition is carried out by sputtering and during any subsequent heat treatments. The refractive index of the protective layer is preferably greater than or equal to the refractive index of the TCO layer. Silicon nitride is particularly preferred.

[0031] It is also possible to place - between the substrate and the layer of transparent electrically conductive oxide - a neutralizing layer or a layer of neutralizing layers. In the case of only one layer, its refractive index is preferably comprised between the refractive index of the substrate and the refractive index of said layer of transparent electrically conductive oxide. Such layers or layer packages allow you to change the image of objects in the reflection of the glazing unit, especially its reflection color. Blue tones with b * negative color coordinates are preferred. As non-limiting examples, it is possible to use a layer of mixed silicon oxide and tin (SiSnOx), glycine or silicon oxynitride, aluminum oxide, mixed titanium oxide and silicon. You can also use a layer package containing two layers with a high and low coefficient, for example the TiO2 / SiO2, Si3N4 / SiO2 or TCO / SiO2 package (in the last case, the TCO may be the same as the TCO already used in the package or another). The geometrical thickness of this layer or these layers is preferably in the range from 15 to 70 nm. When the transparent conductive oxide layer is of fluorine doped tin oxide, the neutralizing sublayer is preferably made of silicon oxycarbide or mixed silicon oxide and tin. When the layer of transparent electrically conductive oxide is ITO, a neutralizing layer of silicon oxynitride or a Si3N4 / SiO2 package is preferably placed under this layer.

[0032] In particular, when the transparent electrically conductive oxide layer is ITO, it is preferable to place - between the substrate and the neutralizing layer or neutralizing packet - an adhesive layer. This layer, which preferably has a refractive index close to the refractive index of the glass substrate, makes it possible to improve the hardening durability, making it easier to attach the neutralizing layer. The adhesive layer is preferably made of silica. Its geometrical thickness is preferably in the range from 20 to 200 nm, in particular from 30 to 150 nm.

[0033] Various preferred embodiments described above can of course be combined with each other. Of course, all possible combinations are not precisely described in this text. Some examples of particularly advantageous packages are given below.

1. Glass / SiOC / SnO2: F / SiO2 / TiO2

2. Glass / SiSnOx / SnO2: F / SiO2 / TiO2

3. Szkło / (SiO2) / SiOxNy / ITO / Si3N4 / SiO2 / TiO2

4. Szkło / SiO2 / Si3N4 / SiO2 / ITO / Si3N4 / SiO2 / TiO2

5. Glass / Si3N4 / SiO2 / ITO / Si3N4 / SiO2 / TiO2 [0034] In these packages, the geometric thickness of the TiO2 layer is preferably maximum 15 nm, in fact 10 nm. As explained earlier in this specification, the thickness of the TCO layer is selected independently, depending on the emissivity required.

[0035] Packets 1 and 2 use a fluorine doped tin oxide TCO layer. These packages are preferably obtained by chemical vapor deposition, usually directly on the float glass production line.

[0036] Packets 3 to 5 that use ITO are preferably obtained by magnetron sputtering. Examples 3 and 4 contain a silica adhesive layer on the glass (optional for example 3), followed by a neutralizing layer of silicon nitride or a neutralizing packet consisting of a silicon nitride layer topped with a silica layer, a TCO layer, a silicon nitride protective layer, intermediate silica and finally a photocatalytic layer of titanium dioxide. Example 5 is in accordance with example 4, but without silica adhesive layer. The formulas do not prejudge the actual stoichiometry of the layers and possible doping.

[0037] The glazing assembly according to the invention is preferably obtained by a multistage process. The packet layers are deposited on a glass substrate, which usually has the form of a large 3.2 * 6m glass pane² or directly on the glass strip during or just after the float process, then the substrate is cut to the final dimensions of the glazing unit. After forming the edge of the edges, a multilayer glazing unit is then produced by joining the substrate with other glass panes, they themselves are optionally provided with functional coatings, e.g. of the low-emission type.

[0038] Different layers of the package can be deposited on the glass substrate by any type of thin layer deposition method. For example, these can be sol-gel methods, pyrolysis (solid or liquid), chemical vapor deposition (CVD), especially plasma-assisted (APCVD), optionally at atmospheric pressure (APPECVD), evaporation.

[0039] According to a preferred embodiment, the packet layers are obtained by chemical vapor deposition, directly on the float glass line. The case where the TCO layer is a fluorine doped tin oxide layer is preferred. Deposition is accomplished by spraying precursors through nozzles onto a hot glass ribbon. Different layers can be deposited in different places of the line: in the flotation tank, between the flotation tank and the cooling tunnel or in the cooling tunnel. The precursors are usually organometallic or halide-type molecules. Examples include fluorine doped tin oxide, tin tetrachloride, monobutyl tin trichloride (MTBCL), trifluoroacetic acid, and hydrofluoric acid. Silicon oxide can be obtained with silane, tetraethoxysilane (TEOS) or in addition hexamethyldisiloxane (HDMSO), optionally using an accelerating agent such as triethyl phosphate. Titanium oxide can be obtained from titanium tetrachloride or titanium isopropoxide. The CVD method, which uses hot glass deposition, has the advantage that a TCO layer and a well crystallized photocatalytic layer are directly obtained.

[0040] According to another preferred embodiment, the packet layers are obtained by sputtering, in particular aided by a magnetic field (magnetron process). The case where the TCO layer is ITO is preferred. In this method, the plasma is generated under high vacuum near the target containing the deposition chemical elements. Active plasma particles, by bombarding the shield, pull out the elements mentioned above, which are deposited on the substrate forming the desired thin layer. This method is called "reactive" when the layer is formed of material resulting from a chemical reaction between elements removed from the target and the gas contained in the plasma. The great advantage of this method lies in the possibility of depositing on the same line a very complex layer package, successively moving the substrate under different discs, and usually in one and the same device.

[0041] However, the magnetron process has a disadvantage when the substrate is not heated during deposition: the obtained TCO and titanium oxide layers are hardly crystallized so that their respective emissivity and photocatalytic activity are not optimal. Therefore, heat treatment turns out to be necessary.

[0042] This heat treatment - the purpose of which is to improve the crystallization of the TCO and photocatalytic layers - is preferably selected from treatments by quenching, annealing, and rapid annealing. Improvement of crystallization can be quantified by increasing the degree of crystallization (percentage mass or volume proportion of crystallized substance) and / or the size of the crystal grains (or the size of the diffractive coherent domains measured by X-ray diffraction or Raman spectroscopy). This improvement in crystallization can also be checked indirectly by improving the properties of the layer. In the case of the TCO layer, the emissivity is reduced, preferably by at least 5% in relative terms, by at least substantially 10% or 15%, as well as its absorption of light and energy. In the case of titanium dioxide layers, the improvement in crystallization results in an increase in photocatalytic activity. Activity is usually assessed by monitoring the degradation of reference impurities, such as stearic acid or methylene blue.

[0043] The treatment by quenching or annealing is usually carried out in an oven suitable for quenching or stress relieving. The entire substrate is brought to a high temperature, at least 300 ° C in the case of stress relief annealing and at least 500 ° C, in fact 600 ° C in the case of quenching.

[0044] Rapid annealing is preferably carried out by means of a flame, plasma torch or laser radiation. This type of method generates relative movement between the substrate and the device (flame, laser, plasma torch). Usually the device is mobile and the coated substrate moves relative to the device so that its surface is processed. These methods make it possible to provide the treated coating with a high energy density within a very short time, thereby limiting heat transfer towards the substrate, and thus heating of said substrate. The substrate temperature during processing is usually a maximum of 100 ° C, even 50 °, in fact 30 ° C. Each point of the thin layer is treated by rapid annealing over a period of time usually less than one second, substantially 0.5 seconds or equal to 1 second, significantly 0.5 seconds.

[0045] Heat treatment by rapid annealing is preferably carried out by means of laser radiation emitting in the infrared or visible range. The radiation wavelength is preferably in the range from 530 to 1200 nm or from 600 to 1000 nm, especially from 700 to 1000 nm, in particular from 800 to 1000 nm. Preferably, laser diodes emitting, for example at wavelengths of 808 nm, 880 nm, 915 or in addition 940 nm or 980 nm are used. Thanks to diode systems, very high powers can be obtained, enabling surface powers to be obtained at the level of the coating treated above 20kW / cm², actually 30kW / cm².

[0046] The laser radiation preferably originates from at least one laser beam forming a line (hereinafter referred to as the "laser line") which simultaneously illuminates the entire width or part of the width of the substrate. This method is advantageous because it avoids the use of expensive handling systems, usually bulky, and special cleaning. The laser beam in the form of lines can be obtained in particular by means of high-power laser diode systems connected to an optical focusing system. The thickness of the line is preferably between 0.01 and 1 mm. The line length is usually between 5 mm and 1 m. The line profile can in particular be a Gaussian curve or blank. A laser line that simultaneously illuminates the entire width or part of the width of the substrate can consist of a single line (which then illuminates the entire width of the substrate) or multiple lines, possibly separated. When multiple lines are used, it is preferred that they are arranged in such a way that the entire surface of the packet is processed. The line or each line is preferably used perpendicular to the direction of movement of the substrate or applied diagonally. Different lines can treat the substrate simultaneously or in a time-shifted manner. It is important that the entire surface to be treated should be treated. The substrate can therefore be moved, in particular shifted, opposite a stationary laser line, usually below but possibly above the laser line. This embodiment is particularly noteworthy for continuous machining. Alternatively, the substrate may be stationary and the laser may be movable. Preferably, the difference between the respective substrate and laser speeds is greater than or equal to 1 m per minute, even 4, indeed 6, 8, 10 or 15 m per minute, in order to ensure a high processing speed. When the ground is displaced, especially by translational movement, it can be activated by any mechanical means of transport, for example by means of belts, rollers, disks in translational movement. The transport system allows you to control and regulate the speed of movement. The laser can also be activated to adjust its distance to the ground, which can be useful especially when the ground is convex, but not only. In fact, it is preferred that the laser beam be focused on the coating being processed such that the latter is placed at a distance less than or equal to 1 mm from the focal plane. If the substrate or laser movement system is not precise enough regarding the distance between the substrate and the focal plane, it should preferably be possible to adjust the distance between the laser and the substrate. This adjustment can be automatic, especially adjustable by measuring the distance before processing.

[0047] The laser generating device may be incorporated into a layer deposition line, for example a magnetic field assisted sputter deposition line (magnetron process) or a chemical vapor deposition line (CVD), especially plasma assisted (PECVD), in a vacuum or at atmospheric pressure (APPECVD).

[0048] The invention also provides the use of a glazing assembly according to the invention to reduce the appearance of condensed water (especially fog or frost) on the surface of said glazing assembly.

[0049] Figure 1 schematically illustrates a cross section of parts of a glazing assembly in accordance with the invention. Only one packet located on surface 1 of the glazing unit and part of the glass substrate is shown.

[0050] Shown on substrate 1 (usually glass), layer 2 of transparent electrically conductive oxide (usually ITO), intermediate layer 3 (usually SiO2) and photocatalytic layer 4 (usually TiO2). Optional layers are protective layer 5 (usually Si3N4), neutralizing layer or neutralizing packet 6 (usually Si3N4 / SiO2 packet) and adhesive layer 7 (for example SiO2).

[0051] The following examples illustrate the invention without, however, limiting it.

EXAMPLE 1 [0052] This example illustrates an embodiment in which the layers are deposited by CVD (chemical vapor deposition) wherein TCO is fluorine doped tin oxide (SnO2: F).

[0053] On the glass substrate, packets consisting of the neutralizing layer of silicon carbide (of the general formula SiOC) with a refractive index 1.65, layers of fluorine doped tin oxide TCO with a refractive index 1.8, an intermediate layer of silica with a factor of 1.48 and finally a photocatalytic layer of TiO2 with a factor of 2.0. As in the whole text, refractive indexes are given for a wavelength of 550 nm.

[0054] The substrate used in the example is a 4 mm thick transparent glass sheet sold by the applicant under the name SGG Planilux®.

[0055] The following table 1 gives for each sample of the invention or comparative example:

- geometrical thicknesses (in nm) of each layer of the packet,

- energy permeability of the substrate covered by the packet (or coefficient of direct solar energy transmittance), denoted TE, in the meaning of the standard

EN 410: 1998,

- the colorimetric coordinates a *, b *, reflected on the packet side, calculated taking as reference the illuminator D65 and the normal observer CIE-1931.

Table 1

<td></td><td>C1</td><td>C2</td><td> 1</td><td> 2</td>

<td>TiO₂ (Nm)</td><td> 15</td><td> 15</td><td> 15</td><td> 15</td>

<td>SiO₂ (Nm)</td><td> 20</td><td> 80</td><td> 50</td><td> 50</td>

<td>SnO₂ : F (nm)</td><td> 300</td><td> 300</td><td> 300</td><td> 300</td>

<td>SiOC (nm)</td><td> 45</td><td> 45</td><td> 45</td><td> 0</td>

<td></td><td></td><td></td><td></td><td></td>

<td>TE (%)</td><td> 71,5</td><td> 71,9</td><td> 72,8</td><td> 72,5</td>

<td>and*</td><td></td><td></td><td> -0,5</td><td> -11,2</td>

<td>b *</td><td></td><td></td><td> -0,9</td><td> 4,4</td>

[0056] Comparative examples C1 and C2 have an intermediate layer whose thickness is not optimal, in contrast to examples 1 and 2 according to the invention.

[0057] In the examples according to the invention, an increase in energy transmission of over 0.5%, in fact 1%, is obtained.

[0058] The comparison between examples 1 and 2 illustrates the operation of the neutralizing layer with SiOC: the packet from example 2, which is deprived of it, has a less neutral, yellow-green reflection image.

[0059] A triple glazing unit was made from substrates C1, C2 and 1. The photocatalytic package 10 is placed on surface 1 of the glazing unit, whereas two silver-based low-emission packages are placed on surface 2 and 5, respectively.

[0060] The following table 2 gives in each case:

- the energy transmittance of the glazing unit (or direct solar energy transmittance factor), denoted TE,

- factor of total solar energy transmittance glazing unit, denoted by g.

[0061] These two quantities are calculated in the sense of EN 410: 1998.

Table 2

<td></td><td>C1</td><td>C2</td><td> 1</td>

<td>TE (%)</td><td> 44,9</td><td> 45,3</td><td> 45,8</td>

<td>g (%)</td><td> 52,1</td><td> 52,5</td><td> 53,1</td>

[0062] The choice of the thickness of the intermediate layer therefore allows a very significant increase in the total solar energy transmission coefficient to be obtained.

EXAMPLE 2 [0063] This example illustrates an embodiment in which the layers are deposited by sputtering (a magnetron process), wherein the TCO is ITO (mixed tin and indium oxide).

[0064] On the glass substrate, packages consisting of starting from the substrate are continuously deposited - a neutralizing package formed from a silicon nitride layer (Si3N4) with a refractive index of 2.0, followed by a layer of silica with a refractive index of 1.48, TCO layers of mixed tin and indium oxide (ITO) with a refractive index of 1.8, intermediate silica layer (SiO2) with a refractive index of 1.48 and finally a photocatalytic layer with

TiO2, whose refractive index is 2.5. The substrate covered with its package is subjected to annealing step after deposition of layers. The substrate is the same as the substrate used in the previous examples.

[0065] The following table 3 gives for each sample according to the invention or comparative example:

- geometrical thicknesses (in nm) of each layer of the packet,

- energy transmittance (or direct solar energy transmittance factor), designated TE, in the meaning of EN 410: 1998, for a substrate covered by a packet,

- color coordinates a *, b *, reflected on the packet side, calculated taking as reference the illuminant D65 and the normal observer CIE-1931.

Table 3

<td></td><td>C3</td><td>C4</td><td> 3</td><td> 4</td>

<td>TiO₂ (Nm)</td><td> 12</td><td> 12</td><td> 12</td><td> 12</td>

<td>SiO₂ (Nm)</td><td> 10</td><td> 70</td><td> 40</td><td> 40</td>

<td>ITO (nm)</td><td> 100</td><td> 100</td><td> 100</td><td> 100</td>

<td>SiO₂ (Nm)</td><td> 11</td><td> 11</td><td> 11</td><td> 0</td>

<td>si₃N₄ (Nm)</td><td> 16,5</td><td> 16,5</td><td> 16,5</td><td> 0</td>

<td></td><td></td><td></td><td></td><td></td>

<td>TE (%)</td><td> 76,3</td><td> 76,2</td><td> 77,9</td><td> 77,4</td>

<td>and*</td><td></td><td></td><td> -4,4</td><td> 10, 6</td>

<td>b *</td><td></td><td></td><td> -9,6</td><td> -20, 6</td>

[0066] Comparative examples C3 and C4 have an intermediate layer whose thickness is not optimal, in contrast to examples 3 and 4 according to the invention.

[0067] The examples according to the invention achieve an increase in energy transmission of at least 1%.

[0068] The comparison between examples 3 and 4 illustrates the operation of the Si3N4 / SiO2 neutralizing packet: the packet from example 4, which is devoid of it, has a less neutral, violet colored reflection image.

[0069] A triple glazing unit is made of the C3, C4 and 3 substrates. The photocatalytic package is placed on surface 1 of the glazing unit, whereas two silver-based low-emission packages are placed on surface 2 and 5, respectively. [0070] The following table 4 gives for each case:

- the energy transmittance of the glazing unit (or direct solar energy transmittance factor), denoted TE,

- the total solar energy transmittance factor of the glazing unit, denoted g.

[0071] These two values ​​are calculated in the sense of EN 410: 1998.

Table 4

<td></td><td>C3</td><td>C4</td><td> 3</td>

<td>TE (%)</td><td> 47,3</td><td> 47,2</td><td> 48,2</td>

<td>g (%)</td><td> 56,0</td><td> 55,8</td><td> 57,0</td>

[0072] The choice of the thickness of the intermediate layer made in accordance with the invention therefore allows a very significant increase in the coefficient of total solar energy transmission of at least 1% in absolute terms to be obtained. The use of ITO also allows an increase in the total solar energy transmission coefficient compared to fluorine doped tin oxide for a comparable level of emissivity (and thus anti-condensation).

[0073] A very thin silicon nitride protective layer can be placed between the TCO layer and the intermediate layer without significantly affecting the optical and energy properties of the glazing unit.

[0074] Various exemplary glazing units allow a very significant reduction in the appearance of condensed water, such as fog or frost.