Glazing

glazing {GLAZING}

<p>The present invention relates as a whole to a transparent or translucent substrate, made in particular of glass, plastic or glass-ceramic, and provided with a coating having photocatalytic properties in order to impart an anti-staining function or more particularly a self-cleaning function.</p>

<p>An important use of these substrates, which can be very versatile, relates to practical glazing, glazing used in household appliances, glazing such as windows for automobiles and windows for buildings.</p><p>Such substrates are also applied to reflective glazing of glass type (residential mirror or automobile rearview mirror) and opaque glazing of apron wall or curtain walling type.</p><p>The present invention may likewise be used for non-transparent substrates, such as ceramic substrates or, in particular, any other substrates that may be used as building materials (metals, tiles, etc.). The present invention preferably applies to generally planar or slightly curved substrates whatever the nature of the substrates.</p><p>Photocatalytic coatings have already been studied. In particular, these photocatalytic coatings are based on titanium oxide crystallized in the form of anatase. The ability of a photocatalytic coating to degrade stains of organic origin or stains of microorganisms under the action of UV radiation is very beneficial.</p><p>Photocatalytic coatings often have hydrophilic properties, which makes it possible to remove inorganic stains by water spray or, in the case of external windows, rain.</p><p>Coatings of this type with anti-staining, bactericidal and algicidal properties have already been described, inter alia, in patent WO 97/10186, which describes several methods for obtaining said properties.</p>

<solutionproblem><p>It is an object of the present invention to improve the technique for depositing coatings, in particular to simplify the technique. At the same time, it is also an object of the present invention to improve the appearance of the coating, more particularly the optical properties of the substrate provided.</p></solutionproblem><meansproblemsolution><p>The present invention is a glazing comprising a first side, a second side, a photocatalytic coating and at least one functional coating, wherein the photocatalytic coating is present on the first side and the photocatalytic coating is oxidized to an at least partially crystallized form. and wherein the functional coating comprises a glazing, present at least on the second side.</p></meansproblemsolution><effectiveness><p>The present invention aims to improve the technique for depositing coatings, in particular to simplify the technique. At the same time, it is also an object of the present invention to improve the appearance of the coating, more particularly the optical properties of the substrate provided.</p><p>The present invention is also applicable to transparent or translucent substrates made of glass, plastic or glass-ceramic and provided with a coating having photocatalytic properties to impart an anti-staining function or, more specifically, a self-cleaning function.</p></effectiveness>

<p>It is therefore an object of the present invention to improve the technique for depositing this type of coating, in particular to simplify the technique. At the same time, it is also an object of the present invention to improve the appearance of the coating, more particularly the optical properties of the substrate provided.</p><p>The formulation of the present invention comprises first depositing a coating having photocatalytic properties by sputtering, said coating comprising titanium oxide which is at least partially crystallized in the form of anatase on a transparent or translucent carrier substrate. It is a feature of the present invention to perform sputtering on a substrate with a deposition pressure of at least 2 Pa. Preferably, the deposition pressure is at most 6.67 Pa, specifically at least 2.67 Pa (ie, at least 15 mtorr, specifically 20 to 50 mtorr).</p><p>Indeed, as is known from the aforementioned patent WO 97/10186, this type of coating can be deposited by sputtering. Sputtering is a vacuum technique, which in particular allows very precise control of the thickness and stoichiometry of the deposited layer. Sputtering is enhanced by magnetic field for higher efficiency. Sputtering may be reactive. That is, in this case, an essentially metallic target is used, which is a titanium-based target (which may be an alloy with other metals or silicon), and sputtering is carried out in an oxidizing atmosphere, usually Ar/O<sb>2</sb> carried out in a mixture. Sputtering may be non-reactive. That is, in this case a target called a ceramic target is used, which is an oxidized form of titanium (which may be an alloy). However, the layer obtained by this type of technology is generally amorphous, whereas the function of the coating according to the invention is directly related to the fact that it must be mostly crystalline. This is why it is necessary to crystallize the coating (or to increase the degree of crystallinity) as recommended in the aforementioned patent, for example, by heat-treating the coating at at least 400° C. for about 30 minutes to several hours.</p><p>In accordance with the present invention, it has been found that a pressure similar to the following is advantageous for the specific crystallization and density/roughness level of the layer, which significantly affects the level of photocatalytic properties of the coating. In some cases, annealing may be an option. More specifically, deposition pressures commonly used for metal oxides are usually in the range of 2 to 8 mtorr (ie 0.27 to 1.07 Pa). Therefore, the present invention uses a deposition pressure that is very rare in this field.</p><p>A post-deposition treatment step is omitted or at least optional (and/or limited by time or temperature) by sputtering the layer on a hot substrate other than room temperature, in particular heating to at least 100° C. It has also been found in the context of the present invention that it is possible to make This heating during deposition is an alternative to, or combined with, the use of high pressure mentioned above.</p><p>Such heating has at least five advantages.</p><p> Saving power during manufacturing,</p><p> the possibility of using substrates that do not withstand heat treatment at a temperature of 400 or 500 ° C, at least without compromising performance;</p><p> Heat treatment according to the present invention when annealing requires that an insert, which is a barrier layer to prevent diffusion of elements from the substrate (which is of the alkali metal type if made of glass), is interposed between the photocatalytic coating and the substrate Possibility to use a thinner barrier layer or even completely eliminate the barrier layer, since it is not much more penetrative than the annealing operation.</p><p> much shorter manufacturing cycles (because the heat treatment of the substrate is substantially shortened and carried out at substantially lower temperatures)</p><p> Eliminates the need to store "semifinished" to be annealed.</p><p>However, the level of photocatalytic activity in a coating is very similar to that of a coating that is deposited and then annealed.</p><p>However, this was not a conventional conclusion, as long as it was considered that a long-term annealing operation was indispensable for the growth of a crystalline seed in the amorphous oxide matrix.</p><p>Thus, it was not clear that the "hot" deposited coating would preferably crystallize in the anatase form rather than the rutile form (the anatase form is much more photocatalytic than the broockite form of titanium oxide).</p><p>In particular, various alternative methods of practicing the present invention exist depending on the type of sputtering equipment available. Therefore, it is possible to heat the substrate outside the vacuum chamber prior to the actual deposition. It is also possible to heat the substrate during deposition if the deposition chamber is particularly equipped with heating means. Therefore, the substrate may be heated before and/or while the coating is sputtered. Heating may be gradual during deposition or may only occur at a portion of the thickness of the layer being deposited (eg the top portion).</p><p>Preferably, when the layer is sputtered, the substrate is at a temperature of 150 to 350 °C, preferably at least 200 °C, more particularly 210 to 280 °C. Surprisingly, it was possible to obtain a sufficiently crystallized layer without the need to heat the substrate to the temperature generally used to carry out annealing operations, ie 400 to 500°C.</p><p>In general, the coating is essentially titanium oxide (TiO<sb>2</sb>) and deposited by sputtering ("hot" or at room temperature), the coating has a very high refractive index - greater than 2 or 2.1 or greater than 2.15 or 2.2. The refractive index is generally 2.15 to 2.35 or 2.35 to 2.50 (which may not be stoichiometric) and more specifically 2.40 to 2.45. This is a characteristic specific to this type of deposition, which is that coatings of the same type deposited by other techniques, e.g. sol-gel techniques, tend to be much more porous and have a significantly lower refractive index (less than 2 and even 1.8 or 1.7). Owing to the present invention, it is possible to obtain by sputtering a layer having a porosity and/or roughness (RMS roughness in detail) of 2.5 to 10 nm, which enhances the photocatalytic properties of the layer. As a result, it can have a refractive index of about 2.15 or 2.35, which is smaller than that normally obtained by sputtering - indirectly demonstrating the porosity of the layer. This is advantageous from an optical point of view, since a layer with a low refractive index has a less reflective appearance for a given thickness.</p><p>It has been observed that the crystallographic structure of a coating is influenced by the fact that the coating is deposited in the cold state and then annealed or deposited in the hot state. Therefore, coatings deposited in the "hot state" and/or at high pressure according to the present invention are unexpectedly, generally less than 50 or 40 or 30 nm, specifically 15 to 30 nm or 20 to 40 nm of TiO.<sb>2</sb> It has an average crystal size. Coatings deposited by standard methods, specifically "cold" and then annealed, contain crystallites of greater size, at least 30 or 40 nm, typically 40-50 nm, when standard deposition pressures are used. tends to do</p><p>On the other hand, when the annealing operation is performed after the coating is deposited at room temperature and high pressure according to one variation of the present invention, the microcrystal size is smaller than the microcrystal size of the coating deposited in a hot state at high pressure or low pressure (20 to 40 nm).</p><p>The photocatalytic activity of the annealed coating after deposition at room temperature and high pressure is much better than the photocatalytic activity of the coating annealed after deposition at room temperature and low pressure. All other things being equal, it is clear that the deposition pressure has a profound effect on the performance of the coating, especially when deposited "cold".</p><p>Heating concurrently with the growth of the layer results in the formation of microstructures conducive to roughness and/or porosity favorable to the photocatalytic properties. This is to some extent the same when high deposition pressures are used (eg, deposition in "cooled state" followed by annealing operation).</p><p>Owing to the method according to the invention (deposition in hot and/or high pressure) coatings with RMS (root mean square) roughness measured by means of atomic force microscopy can be obtained, which measurements have a pitch of 2 μm. (pitch) is performed on the same plane.</p><p>- in the case of annealing after deposition at room temperature and high pressure (2 to 5 Pa) in the sense of the present invention, at least 2 nm, specifically at least 2.5 nm, preferably 2.8 nm to 4.6 nm.</p><p>- at least 4 nm, specifically at least 5 nm, preferably 5.5 to 6.0 nm, in the case of deposition in the hot state (about 250° C.) without annealing at high or low pressure.</p><p>As a comparison, room temperature and standard pressure (specifically 2 × 10<sp>-3</sp>mbar, ie 0.2 Pa), the roughness of the coating which is deposited and then annealed is up to 2 nm. This proves that the use of high pressure makes it possible to achieve very high roughness for the layer deposited by sputtering, which in turn improves the photocatalytic properties of the coating.</p><p>Preferably, the coating has a geometric thickness of less than 150 nm, specifically 80 to 120 nm or 10 to 25 nm. It has been demonstrated that coatings can have sufficient photocatalytic properties (for at least some applications) with the optical advantage of being barely reflective even if they are very thin.</p><p>As indicated above, sputtering of the coating may be reactive or non-reactive. In both cases, the sputtered target may in particular be doped with at least one metal. It may be one or more metals selected from Nb, Ta, Fe, Bi, Co, Ni, Cu, Ru, Ce, Mo, Al.</p><p>In particular, depositing one or more other thin layers having an optical function, an antistatic function, an anti-pigmentation function, an antireflection function, a hydrophilic function or a protective function, or one or more other thin layers to increase the roughness of the coating with photocatalytic properties. One or more steps of depositing may precede and/or follow a deposition method according to the present invention. Thus, it has been observed that it may be desirable to deposit (at least) one layer to give a rough and photocatalytic coating, for example by pyrolysis or sol-gel. The coating then tends to "follow" the roughness of the underlayer and tends to be very rough, whereas the layer deposited by sputtering tends not to be very rough. Therefore, SiO deposited by chemical vapor deposition (CVD)<sb>2</sb>, a sublayer of SiOC or SiON type (for example having an RMS roughness of at least 5 or 10 nm) and then a multilayer having a photocatalytic layer by sputtering can be formed.</p><p>Therefore, the present invention relates to the deposition and thermal decomposition of one or more layers (including at least the photocatalytic coating) by sputtering, specifically pyrolysis {in liquid, vapor or pulverulant}. including any combination of deposition of different layer(s) in multiple layers by concomitant techniques or sol-gel techniques.</p><p>As indicated above, TiO<sb>2</sb>- The basic photocatalytic coating has a high refractive index. This means that the photocatalytic coating is reflective, giving the carrier substrate of the photocatalytic coating a reflective appearance that is often considered to attract little aesthetic interest. In addition to these glossy properties, reflective colors may also be undesirable. Improving this reflective appearance is not straightforward, as the photocatalytic function imposes the limiting condition that the coating must generally be in contact with the external atmosphere in order to receive UV radiation and to break down external stains. Therefore, the coating cannot be covered with a low refractive index layer (unless the low refractive index layer is very thin and/or porous). The coating must also have a certain minimum thickness to be sufficiently effective.</p><p>Therefore, another part of the present invention was to improve the appearance of a reflective substrate without interfering with the photocatalytic activity of the coating, in particular by lowering the light reflection of the coating as low as possible and/or giving the coating a reflective color that is as natural as possible.</p><p>Therefore, the inventive agent is also a transparent or translucent substrate as defined above, wherein at least one of the faces of the substrate is provided at least partially with a photocatalytic coating comprising at least partially anatase-crystallized titanium oxide, wherein the coating comprises It has a high refractive index of at least 2 or 2.1 or 2.2. According to the present invention, this coating is considered to form part of a multilayer consisting of a thin antireflective layer, wherein the coating is the last layer (ie the coating is furthest from the carrier substrate). Since the antireflection multilayer is composed of alternating high and low refractive indexes, in this case it is finished with a layer with a high photocatalytic refractive index. The term "anti-reflective" is used for convenience. That is, it is generally used when it is desired to obtain a light reflection lower than the light reflection of the substrate itself alone. Within the context of the present invention, antireflection is a topic of more than limiting the increase in light reflection (and/or changing or reducing the color of the reflection) caused by using a coating containing titanium oxide.</p><p>Within the context of the present invention, the term "layer" is understood to mean a single layer or an overlap of layers. When layers overlap, the total thickness of the layers is the sum of the thicknesses of each layer and the total refractive index of the layers is the average of the refractive indices of the layers. This also applies to photocatalytic coatings. It may relate to other high refractive index layers.</p><p>Within the context of the present invention and as conceived above, the term "anti-reflective" refers to the light reflection value of a coated substrate in order to make the coated substrate as thin as possible and as natural as possible, i.e., as aesthetically appealing as possible. It is understood to mean a function which makes it possible to lower and/or reduce the reflected color of the coated substrate (which may also be called the "color-resistant" effect).</p><p>This is a very free and unexpected adaptation of a conventional antireflective multilayer. This is because these multilayers are, in a known manner, alternating high and low refractive index layers, finished with a low refractive index (index of refraction as close as possible to that of air with an index of refraction of 1), usually SiO<sb>2</sb>, MgF<sb>2</sb> Because it is based on the back. However, in this case, the multilayer is finished with a high refractive index layer, which is quite paradoxical. Nevertheless, by properly choosing the properties of the various layers, this particular anti-reflective multilayer can be made of high refractive index TiO<sb>2</sb><sb></sb>It significantly reduces intrinsic reflective properties and can impart an acceptable reflective color to the substrate (neutral colors, which are pale shades other than red and other dark colors, are considered less aesthetically appealing and can be gray, blue or especially green is preferred).</p><p>Preferably, the photocatalytic coating has a refractive index of at least 2.30, specifically 2.35 to 2.50 or 2.40 to 2.45 (as seen above, it is also possible to deposit the coating such that the photocatalytic coating has a refractive index of 2.10 to 2.30). The photocatalytic coating is preferably deposited by sputtering. The optical thickness of the photocatalytic coating together with the thickness of the other of the multiple layers is preferably selected to reduce light reflection of the substrate. It has been found that the optimal optical thickness is preferably about λ/2 (where λ is about 580 nm). This corresponds to a thickness of 250 to 350 nm, specifically 270 to 310 nm, and corresponds to a geometric thickness of 80 to 120 nm, in particular 90 to 110 nm. This geometric thickness range was found to be sufficient to obtain photocatalytic activity considered sufficient (photocatalytic activity is actually determined by a number of parameters including thickness, surface roughness, crystalline morphology of the layer, porosity, etc.). In particular, it is also possible to use substantially thinner layers with a geometric thickness of 10 to 25 nm.</p><p>Depending on whether the coating is deposited by sputtering in the "hot" state or by sputtering and annealing at room temperature, it contains microcrystals of varying sizes as seen above (as seen above, typically when sputtered in the "hot" state It contains microcrystals of less than 30 nm, and when sputtered at room temperature and standard pressure, it contains microcrystals of about 30 to 50 nm).</p><p>The antireflective multilayer of the present invention, in its simplest embodiment, comprises three layers, which in turn are a high refractive index layer, a low refractive index layer and a high refractive index photocatalytic coating.</p><p>Apart from the photocatalytic coating, the multilayer high refractive index layer(s) generally has a refractive index of at least 1.9, specifically 1.9 to 2.3 or 1.9 to 2.2. The layer(s) may be made of zinc oxide, tin oxide, zirconium oxide, aluminum nitride or silicon nitride. The layers may be made of a mixture of at least two or more of these compounds.</p><p>The optical thickness of this high refractive index layer is chosen. The optimal optical thickness of this layer is about λ/10, where λ is about 580 nm. This corresponds to an optical thickness of 48 to 68 nm, specifically 53 to 63 nm and a geometric thickness of 20 to 40 nm, specifically 25 to 35 nm. It is also possible to choose smaller thicknesses, in particular from 20 to 48 nm.</p><p>The low refractive index layer(s) generally has a refractive index of 1.4 to 1.75, specifically 1.45 to 1.65. The low refractive index layer(s) may be based, for example, on silicon oxide, aluminum oxide or a mixture of the two. The optical thickness of this low refractive index layer is chosen. The optimal optical thickness of the low refractive index layer is preferably about λ/20, where λ is about 580 nm. This corresponds to an optical thickness of 20 to 79 nm, specifically 19 to 39 nm, specifically 25 to 35 nm and corresponds to a geometric thickness of 12 to 50 nm, specifically 15 to 30 nm, for example 20 to 28 nm.</p><p>According to another variant, in the three-layer multilayer mentioned above, a layer with a "medium" refractive index, that is to say, preferably greater than 1.65 and less than 1.9, will replace the high refractive index layer/low refractive index layer. can A preferred refractive index range is 1.75 to 1.85. The layer may be based on silicon oxynitride and/or aluminum oxynitride. The layer is SiO<sb>2</sb>Oxides of low refractive index such as and at least one SnO<sb>2</sb>, ZnO, ZrO<sb>2</sb>, TiO<sb>2</sb>It can also be based on a mixture of oxides of high refractive index such as</p><p>It is also possible to use such an intermediate layer to replace the first order - a high refractive index layer/low refractive index layer - with a multilayer containing, for example, 5 or 7 layers rather than 3 layers.</p><p>The optical thickness of this intermediate refractive index layer is chosen. The optimal optical thickness is about λ/4, where λ is about 580 nm. This corresponds to an optical thickness of 120 to 150 nm, specifically 125 to 135 nm and a geometric thickness of 65 to 80 nm, in particular 68 to 76 nm.</p><p>As noted above, these various optical thicknesses are selected taking into account the overall appearance of the substrate upon reflection. light reflection value (R<sb>L</sb>. Therefore, it is necessary to find the best compromise so that the overall appearance of the substrate upon reflection is better. Depending on the field of use, lowering the value of R1 [sic] or the specific response of the colorimeter on reflection (e.g., by the a* and b* values of the L,a*,b* colorimetric system or color purity (quantified by the value of the dominant wavelength associated with</p><p>Preferably, all layers of the antireflective multilayer can be deposited one after the other by sputtering in the same manufacturing line.</p><p>According to an optional variant of the present invention, a barrier layer may be interposed between the substrate and the antireflective multilayer to block species likely to diffuse out of the substrate. This kind is, in particular, alkali metals when the substrate is made of glass. For example, the barrier layer is based on silicon oxide (or oxycarbide). SiO<sb>2</sb>can be deposited by sputtering, and SiOC can be deposited by a known method, chemical vapor deposition (CVD). The barrier layer preferably has a thickness of at least 50 nm, for example 80 to 200 nm. If a material of this type with a relatively low refractive index (about 1.45 to 1.55) is chosen, the barrier layer is in fact generally very "intermediate" from an optical point of view. Silicon oxide may in particular contain small amounts of elements selected from Al, C and N.</p><p>The inventive formulations are also glazings, in particular multiple glazings of the single glazing (hard substrate), laminated glazing and double glazing type, the glazing comprising at least one substrate coated in the above-mentioned manner.</p><p>Due to the antireflection effect of the present invention, the glazing preferably has a light reflectivity (R) which is maintained at a maximum of 20%, in particular at a maximum of 18%.<sb>L</sb>) (in terms of multi-layers). Preferably, this light reflectivity is a pleasing shade of blue or green with negative a* and b* values in the (L,a*,b*) colorimetric system, in particular less than 3 or 2.5 in absolute value. has Therefore, these shades are pleasing to the eye and are light shades of low intensity.</p><p>The glazing is one or more other functional coatings (sputtering or pyrolysis or sol) on the same side of the substrate on which the photocatalytic coating is provided or on the opposite side of the substrate or on the side of another substrate that is combined with the first side of the glazing unit (double glazing or laminated glazing). -deposited by gel). Double of the glass/gas-filled cavity/glass type with a photocatalytic coating on the exterior side(s) of the glazing and multiple layers containing one or two silver layers on the interior side (towards the gas-filled cavity) It is also possible to have a glazing unit. The same type of form is used for laminate glazing.</p><p>The other functional coating(s) may be, inter alia, anti-staining, sun blocking, low emissivity, heating, hydrophobic, hydrophilic, anti-reflective or anti-static coatings or other photocatalytic coatings and the like. In particular, mention may be made of one or more layers of silver, or multilayers of low emissivity or sun protection consisting of nickel-chromium or titanium nitride or zirconium nitride. In the case of layers based on metal nitride, it is possible to use CVD techniques.</p><p>The present invention will now be described in more detail by way of example and not by way of limitation.</p><p>Example 1 and Comparative Example 1 were TiO by sputtering<sb>2</sb> It involves depositing the photocatalyst layer while hot.</p><practiceexample><p><u>Example</u><u> 1</u></p><p>It was then deposited on transparent silica-soda-lime glass with a thickness of 4 mm. 80nm SiOC first layer followed by 90nm TiO by CVD deposition<sb>2</sb> Photocatalytic second layer (Al:SiO obtained by reactive sputtering from an Al doped Si target<sb>2</sb>It is also possible to replace the SiOC layer with a layer).</p><p>TiO<sb>2</sb>The layer was deposited by magnetic field enhanced sputtering. This is reactive sputtering from a titanium target in the presence of oxygen. The glass was preheated to a temperature of about 220°C to 250°C. This temperature was kept constant within 5°C while sputtering the layer using a heater positioned opposite the target.</p><p>TiO obtained<sb>2</sb>The layer had a refractive index of 2.44. the TiO<sb>2</sb> The layer was crystallized in the form of anatase (which may also contain amorphous regions), with an average crystallite size of less than 25 nm.</p><p>the TiO<sb>2</sb>The photocatalytic activity of the layers was quantified by a test using palmitic acid. This deposits a given thickness of palmitic acid on the photocatalytic coating and is centered at 365 nm for the entire period of testing, about 50 W/m.<sp>2</sp>Exposure of the deposited palmitic acid to UV radiation having a surface power density of</p><p><img file="KR20070122247A_D0001.tif" /></p><p>The photocatalytic activity by the layer according to the invention is at least 10 nm/h, in particular at least 20 nm/h, in particular 20-100 nm/h, using the above formulas, depending on the choice of the deposition parameters of the pressure and temperature type. has been obtained</p><p>Therefore, the glass coated in two layers is illuminated D<sb>65</sb>, light reflectivity (R<sb>L</sb>) at 23%, the values of a* and b* upon reflection in the (L,a*,b*) colorimetric system were about 17 and 28, respectively.</p><p>Therefore, the photocatalytic activity of the layer is useful but its optical appearance is still clearly reflective with a very intense color.</p><p>It should be noted that the photocatalytic activity of the layer can be increased by subjecting the layer to a conventional annealing operation (at least at 400° C. for 1 hour or several hours) after deposition.</p><p><u>comparative example</u><u> 1</u></p><p>Example 1 was repeated, but this time TiO<sb>2</sb> A layer was deposited on an unheated substrate and then treated at about 500 to 550° C. for 4 hours. Besides, SiO<sb>2</sb> The sublayer was 100 nm thick. The morphology of the layers was slightly different, with an average crystallite size slightly larger than 30 nm.</p><p>the TiO<sb>2</sb>The photocatalytic activity of the layer was similar to that of the unannealed layer of Example 1, but with a smaller thickness of SiO2.<sb>2</sb> If the sublayer was selected, the TiO of Comparative Example 1<sb>2</sb>The photocatalytic activity of the layer was the TiO of Example 1<sb>2</sb>was smaller than the photocatalytic activity of the layer.</p><p>Therefore, it is also confirmed that the deposition in the "hot state" according to the present invention, which makes it possible to "suppress" the often long period of annealing operation, does not impair the performance of the layer. This also confirms additional advantages of the present invention. That is, by depositing hot without annealing, it is possible to use thinner barrier sublayers for the same photocatalytic performance (and thus, again, reduced product manufacturing costs).</p><p>Example 2 and the following examples use TiO of high refractive index to improve the optical properties.<sb>2</sb> bonding a photocatalytic layer to an antireflective multilayer, said high refractive index TiO<sb>2</sb> The photocatalytic layer is deposited in particular by sputtering.</p><p><u>Example</u><u> 2 - (run)</u></p><p>The following multilayer stack was deposited on silica-soda-lime float glass with a thickness of 4 mm.</p><p>Glass / Si<sb>3</sb>N<sb>4</sb><sp>(1)</sp> / SiO<sb>2</sb><sp>(2) </sp>/ TiO<sb>2</sb><sp>(3)</sp></p><p> 30nm 22nm 104nm (geometric thickness).</p><p>Si<sb>3</sb>N<sb>4</sb> Layer (1) was deposited by reactive sputtering from an Al-doped Si target in the presence of nitrogen.</p><p>SiO<sb>2</sb> Layer 2 was deposited by reactive sputtering from an Al-doped Si target in the presence of oxygen.</p><p>Photocatalyst TiO<sb>2</sb> Layer 3 was deposited while hot, as described in Example 1.</p><p>Optionally, glass and Si<sb>3</sb>N<sb>4</sb> Between the layers, the other SiO<sb>2</sb>About 100 nm of SiO prepared as a layer<sb>2</sb>A layer can be inserted as an additional layer [Original text missing]. This layer can act as an alkali-metal barrier layer for glass without substantially affecting the optical properties of the substrate. This is optional, but may be more than that, since the anti-reflective coating layer underneath the photocatalytic layer, ie layers (1) and (2) itself, in addition to their optical properties, constitutes a very satisfactory barrier layer. That is, these two layers form a 100 nm barrier layer for those that are prone to diffusing from glass.</p><p>The photocatalytic activity of layer (3) was 80 nm/h.</p><p>Alternatively, TiO deposited and annealed in the equation state as described in Comparative Example 1<sb>2</sb> Layers may have been used.</p><p>Upon reflection from the multilayer side, the result for this multilayer is as follows. in other words,</p><p>R<sb>L</sb>(Light D<sb>65</sb> under) = 17.3%</p><p>a*(R<sb>L</sb>) = -2</p><p>b*(R<sb>L</sb>) = -2.8</p><p>λ<sb>d</sb>(Main wavelength of light reflection) = 494 nm</p><p>ρe (purity of color in reflection) = 2.5%</p><p>When compared to Example 1, R<sb>L</sb>It shows a significant decrease in values, in which case a paler color of blue-green is obtained. Therefore, the overall appearance in reflection is improved aesthetically and substantially improved.</p><p><u>Example</u><u> 3</u></p><p>This is very similar to Example 2, with the only change being TiO<sb>2</sb> The layer thickness was slightly reduced. </p><p>Here, the following was deposited.</p><p>Glass / Si<sb>3</sb>N<sb>4</sb><sp>(1)</sp> / SiO<sb>2</sb><sp>(2)</sp> / TiO<sb>2</sb><sp>(3)</sp></p><p> 30nm 22nm 99nm (geometric thickness).</p><p>The result at the time of light reflection was as follows (using the same rule as Example 2). in other words,</p><p>R<sb>L</sb> = 17.9%</p><p>a* = -0.8</p><p>b* = -0.7</p><p>λ<sb>d</sb> = 494 nm</p><p>ρe = 0.8%.</p><p>Therefore, in this case, there is a slightly different compromise, R<sb>L</sb>is somewhat larger, but the absolute values of a* and b* are smaller.</p><p><u>Example</u><u> 4 - (</u><u>modelling</u><u>)</u></p><p>This is very similar to Example 2, with the only difference being that the first layer, Si<sb>3</sb>N<sb>4</sb>that the thickness has been changed.</p><p>Glass / Si<sb>3</sb>N<sb>4</sb><sp>(1)</sp> / SiO<sb>2</sb><sp>(2)</sp> / TiO<sb>2</sb><sp>(3)</sp></p><p> 25nm 22nm 104nm (geometric thickness).</p><p>Here is the result for light reflection (using the same rule again)</p><p>R<sb>L</sb> = 15.8%</p><p>a* = 0</p><p>b* = -9</p><p>λ<sb>d</sb> = 475nm</p><p>*ρe = 4.9%.</p><p>In this case, R<sb>L</sb>The value of was significantly lowered, but the color at the time of reflection was slightly changed.</p><p><u>Example</u><u> 5 - (</u><u>modelling</u><u>/comparison)</u></p><p>Here, when compared to Example 2, all thicknesses were changed.</p><p>Glass / Si<sb>3</sb>N<sb>4</sb><sp>(1)</sp> / SiO<sb>2</sb><sp>(2)</sp> / TiO<sb>2</sb><sp>(3)</sp></p><p> 28nm 30nm 75nm (geometric thickness).</p><p>The results at the time of light reflection were as follows.</p><p>R<sb>L</sb> = 25.8%</p><p>a* = -0.3</p><p>b* = -0.7</p><p>λ<sb>d</sb> = 492 nm</p><p>ρe = 0.5%.</p><p>The substrate has a satisfactory color upon reflection, but R well over 20%<sb>L</sb> value, which is too high. That is, the selected thickness is not appropriate.</p><p><u>Example</u><u> 6 - (</u><u>modelling</u><u>/comparison)</u></p><p>This embodiment deviates significantly from the layer thickness recommended by the present invention, with the following multiple layers.</p><p>Glass / Si<sb>3</sb>N<sb>4</sb><sp>(1)</sp> / SiO<sb>2</sb><sp>(2)</sp> / TiO<sb>2</sb><sp>(3)</sp></p><p> 20nm 20nm 60nm (geometric thickness).</p><p>The results at the time of light reflection were as follows.</p><p>R<sb>L</sb> = 30%</p><p>a* = 2.3</p><p>b* = 7.2</p><p>λ<sb>d</sb> = 587nm</p><p>ρe = 14%.</p><p>Multilayers have very high R in reflection<sb>L</sb><sb></sb>Value and not very windy and has a stronger color. Therefore, the appearance of the multilayer upon reflection is not satisfactory.</p><p><u>Example</u><u> 7 - (run)</u></p><p>This time the stack was as follows.</p><p>Glass / SnO<sb>2</sb><sp>(1)</sp> / SiO<sb>2</sb><sp>(2)</sp> / TiO<sb>2</sb><sp>(3)</sp></p><p> 30nm 27nm 105nm (geometric thickness).</p><p>Therefore Si<sb>3</sb>N<sb>4</sb>is SnO<sb>2</sb>, and was deposited by reactive sputtering from a tin target in the presence of oxygen.</p><p>The results at the time of light reflection were as follows.</p><p>R<sb>L</sb> = 17.4%</p><p>a* = -2.8</p><p>b* = -2.7</p><p>λ<sb>d</sb> = 496nm</p><p>ρe = 2.8%.</p><p>The appearance at the time of reflection is similar to that obtained in Example 2.</p><p><u>Example</u><u> 8 - (model)</u></p><p>Here, the first two layers were replaced by a single layer of silicon oxynitride (SiON) with a refractive index of 1.84.</p><p>Therefore, the multilayer was</p><p>Glass / SiON / TiO<sb>2</sb></p><p> 72nm 101nm (geometric thickness).</p><p>The results at the time of light reflection were as follows.</p><p>R<sb>L</sb> = 17.4%</p><p>a* = 0</p><p>b* = -1.08</p><p>λ<sb>d</sb> = 480nm</p><p>ρe = 1%.</p><p>Therefore, the appearance at the time of reflection is satisfactory.</p><p><u>Example</u><u> 9 - (model)</u></p><p>This example is a repeat of Example 8, but the refractive index of the SiON layer is 1.86.</p><p>The appearance at the time of reflection is slightly different from Example 8.</p><p>R<sb>L</sb> = 17.8%</p><p>a* = -1.1</p><p>b* = -1.5</p><p>λ<sb>d</sb> = 494 nm</p><p>ρe = 1.3%.</p><p><u>Example</u><u> 10 (run)</u></p><p>The multilayer was as follows.</p><p>Glass / Si<sb>3</sb>N<sb>4</sb><sp>(1)</sp> / SiO<sb>2</sb><sp>(2)</sp> / TiO<sb>2</sb><sp>(3)</sp> / TiO<sb>2</sb><sp>(3)</sp></p><p> 24nm 17.5nm 24nm 92.5nm</p><p>Therefore, the last high refractive index "layer" is Si<sb>3</sb>N<sb>4</sb> layer and TiO<sb>2</sb> It was layered. Light reflectivity on the multilayer side (R<sb>L</sb>) was 16.5 to 17.5% and the photocatalytic activity was about 80 nm/h.</p><p><u>Example</u><u> 11 (run)</u></p><p>The multilayer type in Example 3 was repeated, but with different thicknesses. The multilayer was as follows.</p><p>Glass / Si<sb>3</sb>N<sb>4</sb><sp>(1)</sp> / SiO<sb>2</sb><sp>(2)</sp> / TiO<sb>2</sb><sp>(3)</sp></p><p> 14.5nm 43nm 14.5nm</p><p>The light reflectivity at the multilayer side was 13 to 16%. If each layer of the stack changed by 3%, the optical change in the coated substrate was as follows.</p><p>R<sb>L</sb> : 0.8%</p><p>Δa* (R<sb>L</sb>) : 0.3</p><p>Δb* (R<sb>L</sb>) : 1.3.</p><p>This example shows a photocatalytic activity of about 15 to 20 nm/h.</p><p>This embodiment is useful in several respects. That is, it will be easy to produce on an industrial scale because it is not greatly affected by the change in thickness. Even if the titanium oxide layer is very thin, this multilayer will retain sufficient photocatalytic properties. It is satisfactory from a colorimetric point of view.</p><p>In conclusion, the present invention is a photocatalytic TiO<sb>2</sb>A new method for vacuum deposition layers containing The present invention also developed a new type of anti-reflective/anti-color multilayer finished with a high refractive index layer, which multilayer is simple to produce on an industrial scale and TiO2 without reducing the photocatalytic properties.<sb>2</sb>significantly reduces the reflex pattern of Due to the present invention, it is possible to obtain a blue or pale green glazing upon reflection, while maintaining a consistent photocatalyst layer thickness of about 100 nanometers. It is also possible to choose a substantially thinner photocatalyst layer of 12 to 30 nm.</p><p>In both aspects (articles and methods) of the present invention, the present invention uses TiO in the same manner.<sb>2</sb>It can be applied to photocatalytic coatings that do not contain</p><p>The present invention therefore proposes that such coatings be deposited "hot" and alternatively deposited at room temperature followed by an appropriate heat treatment in order to obtain a vacuum deposited layer with very specific properties, exhibiting notable stain resistance properties, Here, the deposition pressure is preferably finely controlled.</p></practiceexample>

<p>As described above, the present invention is applicable to transparent or translucent substrates made of glass, plastic or glass-ceramic and provided with a coating having photocatalytic properties to impart an anti-staining function or, more specifically, a self-cleaning function. .</p>