Anti-condensation glass with easy maintenance

1. Field of the invention

The field of the invention is that of glass substrates provided with a multifunctional coating comprising both a layer of transparent conductive oxide and a hydrophilic layer. The coating of the invention is characterized by low roughness, good hydrophilicity and has the additional advantage of preventing the condensation of water. Said coating is chemically and mechanically durable. Its low roughness also offers increased resistance to scratches and marks. The object of the invention is also to describe a process which makes it possible to obtain this type of substrate.

Glass is a material widely used not only in architecture but also in the automobile or in interior applications such as mirrors, shower glasses, decoration, household appliances ... There is a demand for the industry to offer anticondensation and scratch-resistant substrates, the maintenance of which is facilitated in a lasting manner.

2. Prior art solutions

As described in <patcit id="pcit0001" dnum="WO2014198543A"><text>WO2014198543</text></patcit>, it is well known that a glazing can be covered with condensation in the form of mist or frost when the temperature of its surface exposed to humid air drops below the condensation temperature of water. Fogging or frost on the exposed surface of insulating glass is common on high performance multiple insulating glass. In general, for many of these applications, they are multiple glazings comprising at least two glass panes. These panes are arranged at a distance from each other, defining one or more intermediate spaces. Where appropriate, one or more panes comprise a layer of thermal insulation on a face oriented towards an intermediate space. For other applications, they are simple glazing or laminated glazing. This is particularly the case for automotive applications where the formation of frost on the exterior surface is particularly problematic.

Thanks to the thermal insulation the heat losses through the glazing from the interior to the exterior decrease and consequently the probability that the temperature of the exterior surface of the insulating glazing drops during the night below the point of condensation increases, all the more so when the glazing is exposed to the night sky, devoid of clouds.

It is also known that the surface temperature of a glazing can be influenced by the presence of a coating which covers it and modifies its emissivity.

The outward facing side of the exterior pane of the multiple glazing can thus be covered with a low emissive coating. This low-emissivity coating has the effect of slowing the cooling of the face of the glass facing outwards. Thus, the risk that the temperature of this surface falls below the condensation temperature of the humid air to which it is exposed is reduced. This low-emissivity coating then reduces the appearance of condensation or frost on the outside of the insulating glass, it is said to have an anti-condensation or anti-frost effect.

The outer surface being subjected to more severe conditions of chemical and mechanical aggression, the layer must be sufficiently resistant. For this reason, harder layers are generally used such as those obtained by chemical vapor deposition processes. In this regard,<patcit id="pcit0002" dnum="EP0573325A1"><text>EP0573325A1</text></patcit> mentions that transparent conductive oxides (TCO) are particularly suitable for fulfilling the role of low-emissivity layers.

The deposition of a layer between the low-emissivity layer and the substrate can be advantageous in several respects. On the one hand, the said intermediate layer can play the role of barrier layer to the alkaline ions of the glass and on the other hand, the adjustment of the nature and the thickness of such an underlayer allows to optimize the optical aspects such as, for example, the color in transmission and in reflection.

In addition to the low-emissivity layer, which makes it possible to reduce the risk of condensation, it is desirable for the glazing to have a certain hydrophilicity.

It is known that titanium dioxide in at least partially crystallized form, when subjected to UV irradiation, has a photocatalytic effect which allows it to degrade the organic dirt which comes into contact with it. <patcit id="pcit0003" dnum="EP1304366A1"><text>EP1304366A1</text></patcit> and <patcit id="pcit0004" dnum="WO9710186A1"><text>WO97 / 10186A1</text></patcit> largely present the different characteristics of this layer, its mode of operation and its production methods. Besides these photocatalytic properties, always under UV irradiation,<patcit id="pcit0005" dnum="EP1304366A1"><text>EP1304366A1</text></patcit> and <patcit id="pcit0006" dnum="EP1366000A2"><text>EP1366000A2</text></patcit> show that titanium dioxide also has a hydrophilic character which results in a very low contact angle with water, a property which allows the desired effect to be obtained. <patcit id="pcit0007" dnum="EP882686B1"><text>EP882686B1</text></patcit> shows that TiO₂ can also be used to prevent fogging and allows the elimination of residual dirt deposited by forming a homogeneous film of water on the surface of the exterior glazing.

To deposit titanium dioxide, several methods well known in the prior art exist (<patcit id="pcit0008" dnum="WO1997010186A1"><text>WO1997010186A1</text></patcit>, <patcit id="pcit0009" dnum="EP1304366A1"><text>EP1304366A1</text></patcit>). Each method has advantages and disadvantages that will determine the choice. In particular, the TiO film₂ can be deposited by gas phase pyrolysis (CVD), wet (sol-gel) or by vacuum gas phase deposition (PVD). The last process is generally carried out cold and makes it possible to obtain a layer of titanium dioxide which is amorphous and therefore requires annealing in order to be recrystallized. Depending on the annealing temperature used, the crystalline phase obtained will be anatase or rutile. The deposition by sol-gel results in a thick and generally more porous layer, the preparation of which is also more complex. Finally the gas phase pyrolysis involves precursors which are degraded under the effect of the high temperature, to form a layer on the glass. This process can be performed directly online at the time of glass production, making this route particularly attractive and inexpensive. All the more so since the layer resulting from a CVD deposit is a harder, denser layer and exhibiting significant mechanical and chemical resistance properties. Such a layer can in particular be used outdoors, without protective coating. Finally, by the method, the deposition temperature is very high and we obtain TiO₂ directly with a high crystallization rate.

The combination of a low emissivity layer (TCO) and a TiO layer₂ at least partially crystallized makes it possible to obtain a hydrophilic anticondensation glazing, as described in particular in the patent <patcit id="pcit0010" dnum="WO2014198543A"><text>WO2014198543</text></patcit>. This stack has a significant roughness, generally greater than 15 nm. This roughness, generally preferred because it contributes to better photocatalytic activity and better hydrophilicity, is also responsible for greater fouling by encrustation of dirt in the roughness of the surface, as well as a certain difficulty in encrusting these impurities. In addition, the roughness, if it is too high, can make the layer more sensitive to scratches, scratches, marks, stains ... For the skilled person, such sensitivity is problematic during different handling of the glazing or its use. More particularly, in the sector of automotive glazing provided with a low-emissivity layer such as a TCO, the roughness of such a layer subjected to the wiping of wipers, generally has the disadvantage of leaving traces.

What the invention proposes to improve is precisely the problem linked to the question of the roughness of the TCO / TiO stack.₂. How to get a layer of TiO₂ deposited on a transparent conductive oxide layer which makes it possible to maintain good hydrophilicity while presenting a surface which is difficult to soil and to scratch

3. Objectives of the invention

The invention particularly aims to overcome the drawbacks of the prior art by providing a substrate provided with a coating demonstrating both anti-condensation properties, anti-fogging due to its hydrophilic nature and which is difficult to scratch and easy to clean. In addition, the coating of the invention must be able to be subjected to heat treatments such as quenching or bending, without its properties targeted by the invention being deteriorated.

The invention also relates to an economical and easy-to-implement process for depositing a coating having both an anti-condensation property and a strong hydrophilic character and demonstrating good chemical and mechanical durability, in particular good resistance to scratches and scratches.

4. Statement of the invention

The invention relates to a clear, extra-clear or colored, float glass substrate of the silica-soda-lime type, the thickness of which is between 0.2 and 20 mm.

The glass substrate of the invention is provided with a hydrophilic and smooth coating comprising at least one layer of transparent conductive oxide and at least one layer of an oxide of hydrophilic nature.

The layer of transparent conductive oxide (TCO) with a thickness between 150 and 500 nm, preferably between 250 and 350 nm, even more preferably between 300 and 325 nm, has a low emissivity and is generally chosen from oxides transparent conductors such as indium oxide doped with tin (ITO), zinc oxide doped with aluminum (ZnO: Al), zinc oxide doped with indium (ZnO: In ), zinc oxide doped with tin (ZnO: Sn), tin oxide doped with fluorine (SnO₂: F) or antimony doped tin oxide (SnO₂: Sb), this list not being exhaustive. As is well known, the thickness of the TCO layer is adjusted, depending on the nature of the layer, so as to obtain the desired emissivity, which depends on the desired anti-condensation performance. The emissivity of the TCO layer is preferably less than or equal to 0.4, in particular less than or equal to 0.3 and preferably less than 0.2.

A layer having a hydrophilic character is then deposited on the low emissivity layer described above. This layer is chosen from the oxides of Ti, Sn, W, Zn, Si, Al, Ag, Co and mixtures of one or more of these oxides. The thickness of the hydrophilic layer is between 5 and 50 nm, preferably between 5 and 30 nm and even more preferably between 5 and 10 nm. More particularly, the invention relates to the formation of a TiO layer₂ whose thickness is between 5 and 50 nm, preferably between 5 and 30 nm and even more preferably between 5 and 10 nm.

The TiO layer₂ can be doped, in particular with tin in atomic percentages of Sn / Ti less than 10%, preferably less than 5%.

Advantageously, a sub-layer having the function of allowing the neutralization of the color in reflection of the coated pane, that is to say avoiding the interference colors in reflection, can be inserted between the substrate and the conductive layer. It is preferably in direct contact with the glass substrate and is advantageously a monolayer essentially consisting of silicon oxynitride, such as SiO_xNOT_y, or silicon oxycarbons, such as SiO_xVS_y. The refractive index of this sublayer is advantageously in the range from 1.65 to 1.75 and its thickness is preferably between 55 and 95 nm. The values ​​"x" and "y" are chosen to adjust the values ​​of the refractive indices. Alternatively, the neutralization sublayer may be a mixed layer consisting essentially of Sn and Si oxides, the thickness of which is between 55 and 95 nm, advantageously between 60 and 90 nm and very advantageously between 70 and 90 nm.

In another embodiment of the invention, the sublayer is a double sublayer consisting of a first sublayer, closer to the substrate, of a material having a higher refractive index than that of glass such as TiO₂ SnO₂ or ZnO, coated with a second sublayer having a lower refractive index than the first sublayer. This second sublayer is for example a layer of a silicon oxide, silicon oxycarbide, such as SiO_xVS_y, or silicon oxynitride, such as SiO_xNOT_y, x being less than or equal to 2. The thickness of the first sublayer is preferably between 5 nm and 15 nm when it is TiO₂ and preferably between 15 nm and 35 nm when it is SnO₂ or ZnO. The thickness of the second sub-layer is preferably between 15 nm and 40 nm when it is a silicon oxide, oxycarbide, or oxynitride.

The conductive metal oxide layer is preferably a fluorine doped tin oxide layer. It is obtained by pyrolysis of the precursors well known to those skilled in the art. CVD deposition makes it possible to obtain layers which are generally well adherent to the substrate, and of high durability, which is an advantage. More specifically, SnO₂: F is deposited at a glass temperature of between 750 and 550 ° C.

The hydrophilic layer of TiO₂ is in turn deposited, preferably directly on the conductive metal oxide layer, and is also formed by chemical vapor deposition. It is obtained by pyrolysis of the precursors well known to those skilled in the art. Among the precursors generally used, there is titanium tetraisopropoxide (Ti [OCH (CH₃)₂]₄ hereafter called TTIP), titanium tetrachloride (TiCl₄), titanium tetrabutoxide (Ti (OCH₂CH₂CH₂CH₃)₄), titanium ethoxide (IV) (Ti (OC₂H₅)₄) or any mixture of these precursors. More particularly, the TTIP is introduced by means of a coating device above the glass at a temperature lower than that used for the deposition of SnO₂: F.

According to a first embodiment, the stack of layers thus formed is then polished so as to reduce the roughness. In accordance with the knowledge of a person skilled in the art, this polishing has a negative impact on hydrophilicity.

However, to the great surprise of the inventor, the roughness of the stack decreases much more in the stack of the invention than what was obtained until then following the polishing of a layer of SnO₂: F. Indeed, when the transparent conductive oxide layer is surmounted by a hydrophilic layer, the polishing makes it possible to reach values ​​of R_q less than 9 nm, even less than 7 nm and even less than 5 nm. In fact, the equivalent polishing of a transparent conductive oxide layer in the absence of a hydrophilic layer only makes it possible to achieve a roughness of 9 nm.

The inventors have found that the stack of polished layers according to the invention is much smoother to the touch and easier to clean when it is rubbed with a cloth or when its surface is scraped, for example by means of a squeegee. . The stack of polished layers according to the invention is also more difficult to mark during handling, for example when it comes into contact with metallic parts.

According to a second embodiment, the stacking of layers of transparent conductive oxide and of hydrophilic layer thus formed and polished so as to reduce the roughness is heat treated, for example by quenching or bending. The heat treatment to which the substrate of this embodiment of the invention is subjected implies temperatures above 600 ° C. and maintaining the substrate at these temperatures for times which are adapted to the thickness of the substrate according to a well-known process. of the skilled person.

This second embodiment of the invention, in addition to allowing the preparation of a glazing with a roughness much lower than expected, also allows the glazing to regain a hydrophilic character significantly greater than that measured before the heat treatment. This observation is contrary to the teaching of the prior art which shows that a layer of TiO₂ polished and therefore significantly less rough, has poor hydrophilicity. The roughness after heat treatment is substantially identical to the roughness before heat treatment. This completely surprising behavior therefore makes it possible to obtain a coated glass substrate which has both a low roughness and a high hydrophilicity, thus circumventing the limitations of the prior art.

The coated surface of the glazing is an exterior surface. The glass substrates according to the invention can be part of a single or multiple glazing, it can be used for the automobile or in interior applications.

The invention will be better understood by considering the following figures:<ul id="ul0001" list-style="none"><li><figref idref="f0001">Figure 1</figref> : roughness R_q glass / SiO stacking_xVS_y/ SnO₂: F and glass / SiO_XVS_y/ SnO₂: F / TiO₂ polished and unpolished.</li><li><figref idref="f0001">Figure 2</figref> : contact angles, after UV irradiation, of a drop of water, on glass / SiO stacks_xVS_y/ SnO₂: F and glass / SiO_xVS_y/ SnO₂: F / TiO₂ polished and unpolished. Samples not heat treated.</li><li><figref idref="f0001">Figure 3</figref> : contact angle, after UV irradiation, of a drop of water on glass / SiO stacks_xVS_y/ SnO₂: F and glass / SiO_xVS_y/ SnO₂: F / TiO₂ polished and unpolished. Heat treated samples.</li></ul>

A series of CVD coated glasses has been produced, these clear glass samples all carry an SiO neutralization undercoat_xVS_y, a transparent oxide layer of SnO₂: F of 320 nm and a TiO layer₂ whose thickness has been varied.

The <figref idref="f0001">figure 1</figref> shows the roughness Rq (in nm) of some of these polished (P) and unpolished (NP) samples as a function of the thickness of the TiO layer₂ (d (TiO₂), in nm) deposited on a layer of SnO₂: F of 320 nm. These samples have not undergone heat treatment. The values ​​of R_q are substantially identical on samples treated or not. The roughness measurement method is described in more detail below. The<figref idref="f0001">figure 1</figref> shows that in the absence of polishing, the roughness of a layer of SnO₂: F, without TiO layer₂, having a thickness of about 320 nm, is characterized by an R value_q of the order of 13.5 nm.

When a layer of TiO₂ is deposited on a layer of SnO₂: F, we do not observe any change in roughness on the unpolished stack. Indeed whatever the thickness of TiO₂, the roughness remains between 13 and 14 nm.

Polishing the SnO layer₂: F without TiO₂ reduces the roughness value R_q up to about 9 nm.

The inventors have surprisingly observed that when this stack comprises TiO₂ on SnO₂: F, polishing, depending on the thickness of TiO₂, achieves surprisingly low roughness values, less than 5 nm, or even less than 4 nm.

It is thus possible to reach roughness values ​​which until then were not accessible for this type of stacking.

The <figref idref="f0001">figure 2</figref> shows the contact angles with water (AC, in degrees) after UV irradiation of some of these polished (P) and unpolished (NP) samples as a function of the thickness of the TiO layer₂ (d (TiO₂), in nm) deposited on a layer of SnO₂: F of 320 nm. These samples have not undergone heat treatment. The method of measuring the contact angle is described in more detail below. The<figref idref="f0001">figure 2</figref> shows that before heat treatment, the contact angle of a layer of SnO₂: F without TiO layer₂ is around 30 °. This layer therefore has no hydrophilic character. When a layer of TiO₂ is deposited on SnO₂: F, it is necessary to distinguish the unpolished version from the polished version. Indeed, in the case of the unpolished version, the addition of a layer of TiO₂, even of small thickness, allows contact angles less than 5 ° to be obtained.

In the case of the polished version, the deposition of a layer of TiO₂, even if it makes it possible to slightly decrease the contact angle, does not make it possible to obtain satisfactory hydrophilicity values, less than 10 °, in accordance with what the prior art describes.

The <figref idref="f0001">figure 3</figref> shows the contact angles with water (AC, in degrees) after UV irradiation of some of these polished (P) and unpolished (NP) samples as a function of the thickness of the TiO layer₂ (d (TiO₂), in nm) deposited on a layer of SnO₂: F of 320 nm. These samples underwent the same heat treatment. The method of measuring the contact angle is described in more detail below. The<figref idref="f0001">figure 3</figref> shows that, surprisingly, quenching slightly degrades the hydrophilic properties of the unpolished versions while it very significantly improves the hydrophilic properties of the polished versions.

The stacks used to illustrate the invention in the <figref idref="f0001">Figures 1 to 3</figref>, allow to obtain a glazing having an emissivity between 0.14 and 0.16 with low roughness and good hydrophilicity.

For the sake of clarity throughout this document, we adopt the following conventions:<ul id="ul0002" list-style="dash"><li>The tests were carried out on soda-lime glass substrates whose thickness is 4 mm.</li><li>By contact angle (AC), we mean the angle made by the tangent to a drop of water with the surface of the substrate. Depending on the case, the contact angle was measured with or without prior activation by UV radiation. This activation of the hydrophilic nature by UV irradiation is carried out at 40 ° C for a period of 30 minutes by means of UVA with a power of 40 W / m² (UVA-340 nm 40 W / m², from a Q-Panel device, from Q-Lab, Cleveland, Ohio). For a significant impact on the anti-fog effect by the formation of a uniform film of water on the surface of the glass, it is necessary to have a contact angle of less than 10 °, preferably less than 5 °.</li><li>Roughness R_q is the quadratic mean of the height deviations z on the evaluation surface and measured in relation to the mean height <i><o ostyle="single">z</o></i>. The quadratic mean of the deviations of a profile is evaluated by an atomic force microscope (AFM) on a surface of 10 μm times 10 μm in N = 512 lines of M = 512 measurement points according to the following formula:<maths id="math0001"><math display="block"><mrow><msub><mi>R</mi><mi>q</mi></msub><mo>=</mo><msqrt><mrow><mfrac><mn>1</mn><mi mathvariant="italic">MN</mi></mfrac><mrow><mstyle displaystyle="false"><mrow><munderover><mrow><mo>∑</mo></mrow><mrow><mi>x</mi><mo>=</mo><mn>1</mn></mrow><mi>NOT</mi></munderover></mrow></mstyle><mrow><mstyle displaystyle="false"><mrow><munderover><mrow><mo>∑</mo></mrow><mrow><mi>y</mi><mo>=</mo><mn>1</mn></mrow><mi>M</mi></munderover></mrow></mstyle><mrow><msup><mfenced><mi>z</mi><mfenced separators=","><mi>x</mi><mi>y</mi></mfenced><mo>−</mo><mover><mi>z</mi><mrow><mo>‾</mo></mrow></mover><mfenced separators=","><mi>NOT</mi><mi>M</mi></mfenced></mfenced><mn>2</mn></msup></mrow></mrow><mn>.</mn></mrow></mrow></msqrt></mrow></math><img file="EP3431456A1_D0001.tif" /></maths></li></ul>

The measurements were carried out in intermittent contact mode (tapping mode) with a Bruker NCHV type probe, made of antimony doped silicon, of stiffness k between 20 and 80 N / m, with a resonance frequency between 334 and 401 kHz and whose nominal radius of the tip is 10 nm.<ul id="ul0003" list-style="dash" compact="compact"><li>The thicknesses of the indicated layers were determined by X-ray fluorescence (XRF) on the basis of calibration curves. These are geometric or physical thicknesses.</li></ul>

5. Description of preferred embodiments of the invention

The invention is illustrated by the examples which follow and which in no way limit its scope. Advantageously, the sublayer, the transparent conductive oxide layer and the hydrophilic layer are obtained by chemical vapor deposition directly on a production line of clear soda-lime glass, advancing at a speed of 15 m / min and of which l thickness is 4 mm.

A first coating device located above the tin bath, in an area where the glass temperature is around 745 ° C, allows by injection of silane (SiH₄), nitrogen (N₂), carbon dioxide (CO₂) and ethylene (C₂H₄), to obtain an SiO sublayer_xVS_y whose thickness is between 20 and 100 nm, preferably between 60 and 90 nm.

After the deposition of the SiO sublayer_xVS_y, a transparent oxide layer of SnO₂: F is deposited by injecting MBTC (Monobutyl Tin Trichloride), water and HF in an air flow on the glass substrate by means of a second coating device located at the entrance of the gallery at a place where the glass temperature is between 600 and 620 ° C.

Finally, a hydrophilic layer of titanium dioxide is obtained by injecting TTIP and nitrogen via a third coating device above the glass and the layer of transparent conductive oxide, at the entrance to the gallery where the temperature glass is between 580 and 600 ° C.

Below three examples are presented. In accordance with the first embodiment of the invention, Example 1 describes a “transparent conductive oxide / hydrophilic layer” stack and was subjected to in-line polishing. Examples 2 and 3 are counterexamples, not in accordance with the invention. In the case of Example 2, the layer of SnO₂: F is not surmounted by a layer of TiO₂ and the whole thing is polished. Finally, Example 3 does include a layer of TiO₂ on SnO₂: F but the stack was not polished. Table 1 gives the parameters for injecting the gases above the glass for the three examples.<tables id="tabl0001" num="0001"><table frame="all"><title>Table 1: gas injection parameters</title><tgroup cols="12"><colspec colnum="1" colname="col1" colwidth="18mm" /><colspec colnum="2" colname="col2" colwidth="18mm" /><colspec colnum="3" colname="col3" colwidth="12mm" /><colspec colnum="4" colname="col4" colwidth="12mm" /><colspec colnum="5" colname="col5" colwidth="12mm" /><colspec colnum="6" colname="col6" colwidth="12mm" /><colspec colnum="7" colname="col7" colwidth="13mm" /><colspec colnum="8" colname="col8" colwidth="22mm" /><colspec colnum="9" colname="col9" colwidth="10mm" /><colspec colnum="10" colname="col10" colwidth="16mm" /><colspec colnum="11" colname="col11" colwidth="11mm" /><colspec colnum="12" colname="col12" colwidth="15mm" /><thead><row><entry align="center" valign="middle">examples</entry><entry align="center" valign="middle">Polishing</entry><entry namest="col3" nameend="col6" align="center" valign="middle">SiO_xVS_y</entry><entry namest="col7" nameend="col10" align="center" valign="middle">SnO₂: F</entry><entry namest="col11" nameend="col12" align="center" valign="middle">TiO₂</entry></row><row><entry align="center" valign="middle" /><entry align="center" valign="middle" /><entry align="center" valign="middle">NOT₂</entry><entry align="center" valign="middle">VS₂H₄</entry><entry align="center" valign="middle">SiH₄</entry><entry align="center" valign="middle">CO₂</entry><entry align="center" valign="middle">MBTC</entry><entry align="center" valign="middle">H₂O / HF (3%)</entry><entry align="center" valign="middle">H₂O</entry><entry align="center" valign="middle">Gas (Air)</entry><entry align="center" valign="middle">TTIP</entry><entry align="center" valign="middle">NOT₂</entry></row><row><entry align="center" valign="middle" /><entry align="center" valign="middle" /><entry align="center" valign="middle">(kg / h)</entry><entry align="center" valign="middle">(kg / h)</entry><entry align="center" valign="middle">(kg / h)</entry><entry align="center" valign="middle">(kg / h)</entry><entry align="center" valign="middle">l / h</entry><entry align="center" valign="middle">l / h</entry><entry align="center" valign="middle">l / h</entry><entry align="center" valign="middle">Nm³/ h</entry><entry align="center" valign="middle">(l / h)</entry><entry align="center" valign="middle">(Nm³/ h)</entry></row></thead><tbody><row><entry align="center" valign="middle">1</entry><entry align="center" valign="middle">Yes</entry><entry align="center" valign="middle">2,3</entry><entry align="center" valign="middle">3,7</entry><entry align="center" valign="middle">0,95</entry><entry align="center" valign="middle">7,4</entry><entry align="center" valign="middle">32</entry><entry align="center" valign="middle">8,6</entry><entry align="center" valign="middle">7,4</entry><entry align="center" valign="middle">800</entry><entry align="center" valign="middle">2,0</entry><entry align="center" valign="middle">850</entry></row><row><entry align="center" valign="middle">2</entry><entry align="center" valign="middle">Yes</entry><entry align="center" valign="middle">2,3</entry><entry align="center" valign="middle">3,7</entry><entry align="center" valign="middle">0,95</entry><entry align="center" valign="middle">7,4</entry><entry align="center" valign="middle">32</entry><entry align="center" valign="middle">8,6</entry><entry align="center" valign="middle">7,4</entry><entry align="center" valign="middle">800</entry><entry align="center" valign="middle">0</entry><entry align="center" valign="middle">850</entry></row><row><entry align="center" valign="middle">3</entry><entry align="center" valign="middle">No</entry><entry align="center" valign="middle">2,3</entry><entry align="center" valign="middle">3,7</entry><entry align="center" valign="middle">0,95</entry><entry align="center" valign="middle">7,4</entry><entry align="center" valign="middle">32</entry><entry align="center" valign="middle">8,6</entry><entry align="center" valign="middle">7,4</entry><entry align="center" valign="middle">800</entry><entry align="center" valign="middle">2,0</entry><entry align="center" valign="middle">850</entry></row></tbody></tgroup></table></tables>

The roughness of Examples 1 to 3 was measured as described above. Table 2 describes the thicknesses of the layers obtained according to the conditions defined in Table 1 as well as the measurement of the roughness R_q. <tables id="tabl0002" num="0002"><table frame="all"><title>Table 2. Characterization of the stacks obtained.</title><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="21mm" /><colspec colnum="2" colname="col2" colwidth="34mm" /><colspec colnum="3" colname="col3" colwidth="37mm" /><colspec colnum="4" colname="col4" colwidth="34mm" /><colspec colnum="5" colname="col5" colwidth="16mm" /><thead><row><entry align="center" valign="middle">examples</entry><entry align="center" valign="middle">thickness SiO_x (nm)</entry><entry align="center" valign="middle">thickness SnO₂: F (nm)</entry><entry align="center" valign="middle">TiO thickness₂* (nm)</entry><entry align="center" valign="middle">R_q (nm)</entry></row></thead><tbody><row><entry align="center" valign="middle">1 (polished)</entry><entry align="center" valign="middle">75</entry><entry align="center" valign="middle">320</entry><entry align="center" valign="middle">18</entry><entry align="center" valign="middle">4</entry></row><row><entry align="center" valign="middle">2 (polished)</entry><entry align="center" valign="middle">75</entry><entry align="center" valign="middle">320</entry><entry align="center" valign="middle">0</entry><entry align="center" valign="middle">9</entry></row><row><entry align="center" valign="middle">3 (unpolished)</entry><entry align="center" valign="middle">75</entry><entry align="center" valign="middle">320</entry><entry align="center" valign="middle">18</entry><entry align="center" valign="middle">14</entry></row></tbody></tgroup><tgroup cols="5" rowsep="0"><colspec colnum="1" colname="col1" colwidth="21mm" /><colspec colnum="2" colname="col2" colwidth="34mm" /><colspec colnum="3" colname="col3" colwidth="37mm" /><colspec colnum="4" colname="col4" colwidth="34mm" /><colspec colnum="5" colname="col5" colwidth="16mm" /><tbody><row><entry namest="col1" nameend="col5" align="justify">* in these examples, TiO₂ is crystallized in the form of rutile</entry></row></tbody></tgroup></table></tables>

Roughness (R_q) of the stack according to this first embodiment of the invention after polishing is less than 5 nm, thus presenting a very smooth surface, with the advantages which result therefrom. The inventors also studied the hydrophilicity of Examples 1 to 3. The hydrophilicity is evaluated by measuring the contact angle of a drop of water, as described above.

Table 3 describes for Examples 1 to 3, the contact angle measured on the stack without irradiation and on the same stack having been activated by UV radiation. From the values ​​given in table 3, it appears, after UV activation, that the polishing of a stack comprising TiO₂ initially decreases the hydrophilicity. Indeed, before heat treatment, the unpolished counterexample 3 arrives at an intermediate contact angle of 3 ° while the polished example 1 only descends to 21 °. However, this hydrophilic character remains greater than that of a stack not comprising TiO₂ (example 1 vs counterexample 2).<tables id="tabl0003" num="0003"><table frame="all"><title>Table 3. Values ​​of the contact angle on samples according to the examples not heat treated before and after UV activation</title><tgroup cols="3"><colspec colnum="1" colname="col1" colwidth="58mm" /><colspec colnum="2" colname="col2" colwidth="52mm" /><colspec colnum="3" colname="col3" colwidth="57mm" /><thead><row><entry morerows="1" align="center" valign="middle">Examples</entry><entry namest="col2" nameend="col3" align="center" valign="middle">Contact angle measurement (AC)</entry></row><row><entry align="center" valign="middle">inactive</entry><entry align="center" valign="middle">after UV activation (30 min)</entry></row></thead><tbody><row><entry align="center" valign="middle">1</entry><entry align="center" valign="middle">35°</entry><entry align="center" valign="middle">21°</entry></row><row><entry align="center" valign="middle">2</entry><entry align="center" valign="middle">35°</entry><entry align="center" valign="middle">33°</entry></row><row><entry align="center" valign="middle">3</entry><entry align="center" valign="middle">25°</entry><entry align="center" valign="middle">3°</entry></row></tbody></tgroup></table></tables>

Examples 4, 5 and 6 were prepared in the same way as Examples 1, 2 and 3 respectively, but they were further subjected to heat treatment.

In accordance with the second embodiment of the invention, Example 4 describes a “transparent conductive oxide / hydrophilic layer” stack and was subjected to in-line polishing as well as to a heat treatment. Examples 5 and 6 are counterexamples, not in accordance with the invention. In the case of Example 5, the layer of SnO₂: F is not surmounted by a layer of TiO₂ and the whole thing is polished. Finally, Example 6 does include a layer of TiO₂ on SnO₂: F but the stack was not polished.

Table 4 gives the contact angles measured in Examples 4 to 6. Very surprisingly, it appears from these data that the heat treatment slightly degraded the hydrophilic nature of the unpolished stack of counterexample 6 whereas it greatly improved the hydrophilic character of the polished stack (example 4). Regarding stacking without TiO₂ (counterexample 5), the heat treatment has no significant effect.<tables id="tabl0004" num="0004"><table frame="all"><title>Table 4. Contact angle values ​​on samples according to the examples after heat treatment before and after UV activation</title><tgroup cols="3"><colspec colnum="1" colname="col1" colwidth="58mm" /><colspec colnum="2" colname="col2" colwidth="52mm" /><colspec colnum="3" colname="col3" colwidth="57mm" /><thead><row><entry morerows="1" align="center" valign="middle">Examples</entry><entry namest="col2" nameend="col3" align="center" valign="middle">Contact angle measurement (CA)</entry></row><row><entry align="center" valign="middle">inactive</entry><entry align="center" valign="middle">after UV activation (30 min)</entry></row></thead><tbody><row><entry align="center" valign="middle">4</entry><entry align="center" valign="middle">28°</entry><entry align="center" valign="middle">9°</entry></row><row><entry align="center" valign="middle">5</entry><entry align="center" valign="middle">29°</entry><entry align="center" valign="middle">27°</entry></row><row><entry align="center" valign="middle">6</entry><entry align="center" valign="middle">25°</entry><entry align="center" valign="middle">7°</entry></row></tbody></tgroup></table></tables>

This last observation shows that very surprisingly, a coated glass according to the invention and heat treated, has, in addition to its anti-condensation properties, a low roughness and a very good hydrophilic character which gives it an anti-fog property and facilitates the cleaning. In particular, such a low roughness gives the stacking good resistance to scratches and scratches.