MXPA98002018A - Substrate with fotocatalit coating - Google Patents

Abstract

The present invention relates to: The subject of the invention is a substrate (1) with a glass, ceramic or glass ceramic base, provided on at least part of at least one of its faces with a coating 3 with photocatalytic property, which contains titanium oxide at least partially crystallized. It also concerns the applications of such a substrate and its way of obtaining

Description

f SUBSTRATE WITH FOTOCATALI T ICO COATING * DESCRIPTION OF THE INVENTION The invention relates to glass-based substrates, ceramics or glass-ceramics, especially in glass, particularly transparent ones, provided with coating with photocatalytic properties for the purpose of 0 glass-making plants with various applications, such as stained-glass windows for commercial uses. , stained glass for vehicles or for buildings. Increasingly, it seeks to make the windows functional, placing on its surface, 5 films designed to give them a particular property according to the application that will be given to them. Thus, there are films with optical function such as the so-called ant i-re fie j o, composed of an alternative superposition of films with high and low refractive indexes. For antiaesthetic or heating function of the anti-i-shell type, the electrically conductive films with metal base or sensitized metal oxide can be considered; for a thermal, low emission or anti-solar function, for example, we can tilt by metal films, of the silver type or by the base of a metal oxide nitride. To obtain an "anti-rain" effect, water-repellent films, for example fluorinated organo silane, can be considered. However, there is still a need for a substrate, in particular a glazing that could be called "anti-lining", that is, which aims at the permanence in time of the properties of the appearance and the surface, and which allows especially , space the cleanings and / or improve the visibility, getting rid of the sludge, as they progressively deposit on the surface of the substrate, especially the slides of organic origin such as fingerprints or volatile organic products present in the atmosphere, or even muddies such as dew or mist. Now, it is known that there are certain semi-conductive metallic oxide materials, which are suitable, under a radiation of adequate wavelength, to initiate radical reactions that cause the oxidation of organic products: generally speaking of "photocatalytic materials" "or also" photoreactive ".

The invention also has as its object the preparation of photocatalytic coatings on a substrate, which has a remarkable "anti-cutting" effect with respect to its substrate and which can be industrialized. The object of the invention is a glass, ceramic or glass-ceramic base substrate, in particular transparent glass, provided on at least a portion of at least one of its faces with a coating with photocatalytic property, containing oxide of titanium at least partially crystallized. The titanium oxide is preferably crystallized "in situ" at the time of coating the substrate. Titanium oxide is actually one of the semiconductors that, under the effect of light in the range or visible light of ultraviolet rays, degrade the organic products that are deposited on its surface. Extracting the titanium oxide to make a window with "anti-slips" effect is then the most indicated, so that this oxide has a good mechanical and chemical resistance: to be effective for a long time, it is obviously important that the coating retains its integrity, even when it is directly exposed to numerous aggressions, especially at the time of setting up the show window during a black construction (in a construction) or during the production line (in a vehicle), which implies repeated manipulations by means of Mechanical or pneumatic grip and also once the window in its place has risks of abrasion (windscreen wipers, abrasive rags) and contact with aggressive chemicals (atmospheric pollutants such as sulfur dioxide (S02), cleaning products ...). In addition, we chose them for the choice of titanium oxide that is at least partially crystallized because it was shown to have much better performance in terms of photocatalytic property than amorphous titanium oxide. Preferably, it is crystallized under the anatase form, under the rutile form or under a mixture of anatase and rutile with a crystallization rate of at least 25%, especially around 39 to 80%, particularly near the surface, (this property being rather a surface property). (It is understood by a crystallization cup of the amount by weight of crystallized titanium dioxide (Ti02) in relation to the amount of the total weight of titanium dioxide in the coating). It was also observed, especially in the case of a crystallization under the anatase form, that the orientation of the titanium dioxide (Ti02) crystals that cross the substrate have an influence on the photic performance of the oxide: there is an orientation privileged (1,1,0) that totally favors the fot ocatál is is. Advantageously, the manufacture is operated in such a way that the crystallized titanium oxide it contains is found in the form of "crist alitas", at least on the surface, that is, of monocri st ale s, which have an average size comprised between 0.5 and 100 nm, preferably from 1 to 50 nm, especially 10 to 40 nm, and very particularly between 20 and 30 nm. Indeed, in this range of dimensions, the oxide seems to have an optimal photocalitic effect, most likely because crystallites of this size, deploy an important active surface. As we will see in more detail later, the coating based on titanium oxide can be obtained in many ways: | | by decomposition of titanium precursors (pyrolysis techniques: chemical pyrolysis, powder pyrolysis, phase pyrolysis called CVD (Chemical Vapor Deposition), soil-gel techniques: soaking or submerging, cell coating, ...), [_ | by a vacuum technique (with reactive or non-reactive sputtering). In addition to the crystallized titanium oxide, the coating can also contain at least some other type of mineral material, in particular in the form of an amorphous or partially crystallized oxide, for example an oxide of silicon (or mixture of oxides), of titanium, tin, zirconium or aluminum. This mineral material can also participate in the phthacatalytic effect of the crystallized titanium oxide, presenting itself a certain photocatalytic effect, even when it is weak in relation to that of the crystallized titanium dioxide (Ti02), this is the case of the oxide tin or amorphous titanium oxide. A "mixed" oxide film combining at least partially crystallized titanium oxide with at least one other oxide may be interesting from an optical perspective, especially if the other or the other oxides are chosen from the lower index of titanium dioxide ( T iO2): by reducing the "overall" refractive index of the coating, it is possible to play with the luminous reflection of the substrate provided with the coating, in particular to reduce this reflection. This would be the case if, for example, a film were chosen in Ti02 / Si02, one of the ways of obtaining it is described in document EP-0 465 309, or of Ti02 / Si02. It is necessary, of course, that the coating contain an amount of titanium dioxide (Ti02) sufficient to maintain an aliquot photocat activity that is noticed. It is therefore considered that it is preferable that the coating contains at least 40% of the best weight if it is at least 50% by weight of titanium dioxide (TiO2) relative to the total weight of oxide or oxides in the coating. It is possible to choose to add to the coating, following the invention, an oil-repellent and / or hydro-repellent film which is stable or resistant to photocatalysis, for example on the basis of the fluorinated organosilane described in US Pat. 368 892 and US-5 389 427, as well as pe r flouroalqui 1 if the one described in the application of document FR-94/08734 of July 13, 1994 published under number FR-2 722 493 and corresponding to the European document EP-0 692 463, especially with the formula: CF3- (CF2) n- (CH2) m.SiX3 wherein n is from 0 to 12, m from 2 to 5 and X is a hydrolysable group. In order to extend the photocatalytic effect of the titanium oxide of the coating according to the invention, it is first of all possible to increase the absorption range of the coating, by incorporating into the coating other particles, in particular metallic and based on cadmium, tin, tungsten, zinc, cerium, or zirconium. The number of charge carriers can also be increased by excitation of the crystalline network of titanium oxide, by adding at least one of the following metallic elements: niobium, tantalum, iron, bismuth, cobalt, nickel, copper, ruthenium, cerium, molybdenum. This excitation can also be done by excitation of the surface of the titanium oxide alone, or by excitation of the coating as a whole.

The excitation of the surface is carried out by coating at least a part of the coating, a film of oxides or metal salts, having chosen the metal between the iron, copper, ruthenium, cerium, molybdenum, vanadium or bismuth. Finally, the photocatalytic phenomenon can be extended by increasing the yield and / or the kinetics of the photic alkylation reactions, by coating the titanium oxide or at least a part of the coating that incorporates it, with a noble metal in the form of a film. of platinum, rhodium, silver, palladium. A catalyst, for example, placed with a vacuum technique, allows in fact to increase the number and / or the lifetime of the radical entities created by the titanium oxide, and thus favors the chain reactions that lead to the degradation of organic products. Surprisingly, the coating has in fact not only one but two properties, from the moment it is exposed to adequate radiation such as the range of visible light and / or ultraviolet rays, such as solar radiation: due to the presence of titanic oxide fot ocat alí tico, as we have seen, progressive disappearance is favored as it accumulates, from the slides of organic origin causing its degradation by a radical oxidation process. Mineral waste is not degraded by this process; they then remain on the surface, and apart from certain crystallisations, a part is easily evacuated, since they have no reason to adhere to the surface, since the organic agents that stuck it were degraded by fotcacatál is i s. But the coating of the invention, which is self-cleaning permanently, then preferably has an outer surface with pronounced hydrophilic and / or oleophilic characteristics, which leads to three very beneficial effects: II a hydrophilic characteristic allows a perfect soaking by part of the water that can be deposited on the coating. When a phenomenon of condensation of water occurs, instead of a deposit of water droplets in the form of dew or that hinders visibility, we have a thin continuous film of water that forms on the surface of the coating and that is completely transparent. This "anti-sweat" effect is especially demonstrated by the measurement of a contact angle with water less than 5o after exposure to light, and, II after it is water, especially rain, on a surface not treated by water. a photocatalytic film, numerous drops of rainwater remain stuck on the surface and leave, once evaporated, unsightly and obstructive traces of mainly mineral origin. Effectively, a surface exposed to the ambient air is quickly coated with a layer of debris that limits its soaking by water. These residues come to be added to the others, especially the minerals (crystallizations, ...) brought by the atmosphere in which the glass is immersed. In the case of a photoreactive surface, these mineral residues are not directly degraded by fot ocatál is is. In fact, they are mostly eliminated thanks to the hydrophilic characteristic caused by the photocalcal activity. This hydrophilic characteristic in fact provokes a perfect adaptation of the raindrops. Therefore the remnants of evaporation are never present. In addition, the other mineral residues present on the surface are washed or re-dissolved in case they crystallize, by a film of water and therefore are mostly evacuated. An "anti-mineral-mineral effect" is obtained, especially caused by the rain, Co, together with this hydrophilic characteristic, the coating can also present an oleophilic characteristic, which allows the "soaking" of the organic slides that, as with the water, then tend to deposit on the coating in the form of a continuous film less visible than the "spots" well located. There is thus an effect "organic anti-scuffing" that is operated in two stages: at the moment in which it is deposited on the coating, the embossing is already little visible. Then, progressively disappears by radical degradation initiated by fotocatáli is. The coating surface can be chosen more or less smooth. Some rugosity may in fact be advantageous: 1 1 allows to deploy a larger active photocatalytic surface and therefore that causes a greater photocatalytic activity, I I has a direct influence on the soaking. The roughness exalts in fact the soaking properties. A hydrophilic smooth surface will be even more hydrophilic once it becomes rough. By "rugosity" is meant here both the surface roughness and the roughness caused by a porosity of the film in at least a part of its thickness. The foregoing effects will be all the more marked when the coating is more porous and rough, from which a super hydrophilic effect of the rough photoreactive surfaces results. However, too pronounced, the roughness can be dislodged, by favoring the incrustation, the accumulation of residues and / or by appearing optically unacceptable level of opacity. It was thus revealed, interestingly, to adapt the precipitation mode of the coatings based on titanium dioxide (Ti02), so that they can have a roughness of around 2 to 20 nm, preferably of 5 to 15 nm. This rugosity was evaluated with an atomic microscope, measuring the value of the mean square interval (called "Root Mean Square" or RMS in English) on a surface of one square micrometer.With these rugosities, the coatings present a hydrophilic characteristic that translates into an angle It was also found that it was advantageous to favor a certain porosity in the thickness of the coating, so that, if the coating consists only of titanium dioxide, it preferably has a porosity of less than 10%. order of 65 to 99%, especially 70 to 90% Porosity was defined here indirectly by the percentage of the theoretical density of titanium dioxide, which is around 3.8 To favor such porosity, a medium consists, for example, in precipitating the coating with a soil-gel type technique that involves the decomposition of organo-metallic materials.; it is then possible to introduce into the solution, in addition to the organic-metallic precursor (s), an organic polymer of the polyethylene glycol PEG type: by hardening the film by heating, the PEG is burned, and a certain porosity in the thickness is generated or increased. of the layer. The thickness of the coating according to the invention is variable, it is preferably between 5 nm and one micron, in particular between 5 and 100 nm, especially between 10 and 80 nm, or between 20 and 50 nm. In fact, the choice of thickness may depend on different parameters, in particular on the intended application of the glass substrate, also on the size of the crystallites of titanium dioxide (Ti02) in the coating or on the presence of alkalis in a large proportion the substrate. Between the substrate and the coating, according to the invention, one or more other films can be placed with different or complementary functions to that of the coating. It may be, in particular, films with antistatic, thermal, optical function, or that favor the crystalline growth of titanium dioxide (Ti02) in its anatase or rutile form, or of layers that form a barrier to the migration of certain elements coming from of the substrate, especially that they make a barrier against the alkalies and very especially before sodium ions when the substrate is made of glass. It is also possible to consider a superposition of layers "ant i-re fiej ant e" alternating high and low refractive index films, the coating, according to the invention, constitutes the last layer of the superposition. In this case, it is preferable that the coating be of a relatively low refractive index, which is the case when it is constituted of a mixed oxide of titanium and silicon. The film can be chosen with anti-static or thermal function (heating when it is provided with current conductors, low emissivity, anti-solar, ...) or, in particular, based on a metallic conductive material, such as silver, or excited metal oxide, such as tin-excited indium oxide ITO, tin oxide excited with a halogen such as fluorine Sn02: F, or with antimony Sn02: Sb; or with zinc oxide excited with indium ZnO: In with fluorine with tin ITO tin oxide excited with a halogen of the fluoro type Sn02: F or antimony Sn02: Sb, or zinc oxide excited with indium ZnO: In, with Fluorine ZnO: F, with aluminum ZnO: Al or with tin ZnO: Sn. It can also be metal oxides sub-es tequióme trieos in oxygen, such as Sn02-x or Zn02x avec X < 2.

The film with anti-static function preferably has a square resistance value of 20 to 1000 ohms / square. It can be provided to provide it with current conductors to polarize it (supply voltages, for example between 5 and 100V). This controlled polarization makes it possible especially to fight against the accumulation of lint of a size of the order of a millimeter susceptible to being deposited on the coating, especially of dry lint that adhere by electro-static effect: reversing the polarization of the film abruptly, " they eject "these fluffs. The film with optical function can be chosen in order to reduce the light reflection and / or make the color reflected from the substrate more neutral. Presented in this case, preferably, an intermediate refractive index between the coating and the substrate and an appropriate optical thickness, and may be constituted by an oxide or a mixture of oxides of the type aluminum oxide A1203, tin oxide Sn02, indium oxide ln203, oxycarbide or silicon oxynitride. To obtain the maximum attenuation of the color that is reflected, it is preferable that this film has a refractive index close to the square root of the product of the squares of the refractive indexes of the two materials that frame it, that is, the substrate and the coating according to the invention. At the same time, it is advantageous to choose its optical thickness (ie the product of its geometrical thickness and its refractive index) close to the lambda / 4, where the average wavelength of the visible light is approximately lambda, in particular around 500 at 550nm. The film with a barrier function for alkalis can be selected, in particular, from an oxide, nitride, oxynitride or silicon oxycarbide base, from aluminum oxide containing fluorine A1203: F, or else from aluminum nitride. In fact, it was found useful when the substrate is glass, then the migration of sodium ions to the coating according to the invention can, under certain conditions, alter the photocatalytic properties. The nature of the substrate or of the sub-film then has a supplementary interest: it may favor the crystallization of the aliquot photic film which precipitates, especially in the case of precipitation of the CVD.

Thus, at the time of CVD precipitation of titanium dioxide (Ti02), a sub-particle of crystallized Sn02: F favors the increase of titanium dioxide in the form of rutile mostly, especially for precipitate temperatures of the order of 400 ° to 500 ° C, while the surface of a sodium-calcium glass or of a sublayer of silicon oxycarbide causes an anatase increase, especially for precipitate temperatures of the order of 400 ° to 600 ° C. All these optional films can, in a known manner, be precipitated by vacuum techniques of the cathodic sputtering type or by other techniques of the thermal decomposition type such as pyrolysis in solid, liquid or gaseous phase. Each of the aforementioned films can have several functions, but they can also be overridden. The object of the invention is also the "anti-waste" (organic and / or mineral waste) and / or "anti-dew or vapor" stained-glass windows, whether monolithic, individual multiple of the double-glazed type or of several sheets of glass , and which incorporate the coated substrates described above. The invention then aims to manufacture glass, ceramic or vitro-ceramic products, and especially the manufacture of "self-cleaning" stained-glass windows. These can advantageously be part of stained-glass windows of constructions, such as double stained-glass windows (the covering can be arranged "on the outside" and / or "on the inside", that is on the face 1 and / or on the face 4). This is particularly interesting for stained-glass windows which are difficult to clean and / or which need to be cleaned very frequently, like the stained-glass windows of the roofs, the windows of the airports, ... These can also be showcases for vehicles in which maintaining visibility is an essential criterion of safety. This coating can also be placed on the windshields, the sides or the rear medallion of the cars, especially on the face of the stained glass windows facing the interior of the cabin. This coating can then prevent the formation of dew or fog, and / or remove the marks of embarrassments, such as fingerprints, nicotine or organic material of the plastic type that float detached from the plastic covering the interior of the cabin, especially of the driver's board (detachment sometimes known under the English term "fogging"). Other vehicles such as airplanes or trains may also find it interesting to use stained glass with the coating of the invention. Many other applications are possible, especially for aquarium glasses, shop windows, greenhouses, glass galleries, glass used in interior furnishing or urban furniture, but also in mirrors, glass screens television, in the field of eyeglasses or all architectural material of the facade material type, transport of trusses, roofing, such as tiles, ... The invention thus makes these known products functional, conferring anti-ultraviolet properties , ant i-re s iduos, bactericide, ant i-refle j ante, anti-static, anti microorganisms ... Another interesting application of the coating according to the invention consists in associating it with electrically controlled variable absorption windows of the elect rocromas stained glass type, glazing of liquid crystals, possibly with dichroic dye, stained-glass windows with a suspended particle system, stained-glass windows All of these stained glass windows are generally made up of a plurality of transparent substrates between which the "active" elements are arranged, it is then possible to arrange the coating on the outer face of at least one of these substrates. Especially in the case of the elect rocroma window, when it is colored, its obstruction leads to a certain heating of its surface, which in fact, can accelerate the photocatalytic decomposition of the carbonaceous substances that have been deposited on the coating according to the invention. For more details on the structure of an elect rocroma glass, it can advantageously refer to the application of EP-A-0 575 207 which describes a double glazing with several glasses and clochromes, the coating according to the invention can preferably be arranged on face 1.

Another subject of the invention is the different methods for obtaining the coating according to the invention. A precipitation technique of the pyrolysis type can be used, since it allows, in particular, precipitation of the coating without interruption, directly on the glass strip when a glass substrate is used. The pyrolysis can be carried out in solid phase from powder or powders of precursor (s) of the organometallic type (s). The pyrolysis can be carried out in liquid phase, from a solution comprising an organo-metallic titanium precursor of the titanium chelate and / or titanium alcoholate type. Such precursors are mixed with at least one other organometallic precursor. For more details on the nature of the titanium precursor or on the conditions of the precipitate, it can refer, for example, to documents FR-2 310 977 and EP-0 465 309. Pyrolysis can also be carried out in the vapor phase, which technique is designated also under the term CVD (Chemical Vapor Deposition), from at least one precursor of the titanium of the halide type such as TiCl 4 or titanium alcoholate of the type t et ra is opropylate of titanium, Ti, Ti (OiPr) 4. The crystallization of the layer can then be controlled by the sublayer type, as stated above. It is also possible to precipitate the coating by other techniques, in particular by the techniques associated with the "soil-gel". Different precipitation modes are possible, such as "immersion" also called "dip-coating" submersion coating or a precipitate with the help of a cell called "cell-coat ing". It can also be a "spray-coating" mode or by laminar impregnation. This latter technique is detailed in the application of WO-94/01598. All these precipitate modes generally use a solution comprising at least one organometallic precursor, in particular titanium, of the alcoholate type which is thermally decomposed after impregnation of the substrate with the solution on one of its faces, or in its two faces. On the other hand, it may be interesting to precipitate the coating, whatever the technique of precipitate that is intended to be used, not only once, but in at least two successive stages, which seems to favor the crystallization of titanium oxide. throughout the thickness of the coating when, a relatively thick one is chosen. Also, it is advantageous to pass the coating with photocatalytic properties, after the precipitate, by a heat treatment of the annealing type. A thermal treatment is essential for a soil-gel or lamellar impregnation technique to decompose the organo-metallic precursor (s) into oxide, once the substrate has been impregnated and the abrasion resistance is improved, which is not the case. case when a pyrolysis technique is used where the precursor decomposes from the moment it comes into contact with the substrate. In both the first and the second case, however, a post-precipitated heat treatment, once the Ti02 titanium dioxide has been formed, improves its crystallization rate. The temperature of the chosen treatment can then allow better control of the crystallization rate and the crystalline, anatase and / or rutile nature of the oxide. However, in the case of a sodium-calcium glass substrate, multiple and controlled annealing can favor an attenuation of the photochemical activity due to the high migration of alkalis from the substrate towards the photoreactive layer. The use of a barrier layer between the substrate, if it is standard glass, and the coating, or the selection of a glass substrate of suitable composition, or even more so the selection of a sodium-calcium glass whose surface is salted, allow exempt of this risk. Other details and advantageous features of the invention stand out from the above description, from non-limiting embodiments, with the help of the following figures: FIG. 1: a cross section of a glass substrate provided with the coating according to the invention, FIG. 2: a diagram of a soil-gel precipitate technique, called "dip" or "dip-coating" of the coating, figure 3: diagram of a precipitate technique called "cell-coating", figure 4: diagram of a precipitate technique called "Spray-coating", figure 5: Schematic of a technique of precipitate by laminar impregnation. As shown schematically in FIG. 1, all the examples that follow concern the precipitate of a coating 3 called "ant i-residues" essentially based on titanium oxide on a transparent substrate 1. The substrate 1 is made of glass clear silico or sodium-calcium 4 mm thick and 50 cm long and wide. It is understood that the invention is not limited to this specific type of glass. The glass can then not be flat, but domed. Between the coating 3 and the substrate 1, there is an optional film 2, based on silicon oxycarbide, written as SiOC, to constitute a barrier against the diffusion of the alkalis and / or an attenuating layer against the light reflection, that is to say a tin oxide base excited with fluorine Sn02: F to constitute an antistatic and / or low emissivity film, even with low accentuated low emission effect, and / or which attenuates color especially during reflection.

Elos 1 to 3 Examples 1 to 3 refer to coating 3, precipitated with the aid of a liquid phase pyrolysis technique. It is possible to proceed without interruptions, using an adapted distribution tube, arranged transversely and above the band of the floating glass, at the exit of the floating bath cubicle itself. Here, we proceeded discontinuously, using a mobile tube disposed in front of the substrate 1 already trimmed to the dimensions indicated, substrate that was or was first heated in an oven at a temperature of 400 to 650 ° C before passing at constant speed through the tube throwing an appropriate solution.

EXAMPLE 1 In this example, there is no optional layer 2. The coating 3 is precipitated with the aid of a solution containing two organic titanium precursors such as titanium, the di-i sopropoxy di-acetylacetonate of titanium and the tetraoctylene glycol titanium dissolved in a mixture of two solvents, which are ethyl acetate and isopropane acetate 1. It can be noted that other precursors of the same type are also completely usable, in particular titanium chelates of the titanium acetylacetonate, methylacetoacet al or titanium, and titanium toacetate types or the t-aminaminotr i-et anol or the titanoamino di-ethanol. As soon as the substrate 1 reaches the desired temperature in the furnace, especially around 500 ° C, it passes through the tube, projecting the indicated mixture at room temperature with the help of compressed air. A layer of titanium dioxide of about 90 nm in thickness is then obtained, this thickness can be controlled by the rate of passage of the substrate 1 through the tube and / or the temperature of said substrate. The layer partially crystallizes anatase. This layer has an excellent mechanical resistance. Its resistance to abrasion tests is comparable to that obtained by the surface of the simple glass. It can warp and is impregnable. It does not present opacity; the diffuse light transmission of the coated substrate is less than 0.6% (measured according to the illuminant D6s at 560 nm).

EXAMPLE 2 Repeat example 1 but insert a layer 2 in Sn02: F of 73nm in thickness between substrate 1 and coating 3. This layer is obtained by powder pyrolysis from dibutyltin difluoride DBTF. It can also be obtained, as is known, by pyrolysis in liquid or vapor phase, as described, for example, in the application of EP-A-0 648 196. In the vapor phase, it is possible in particular to use a mixture of monobutyl tin trichloride and a fluorinated precursor optionally associated with a "moderate" oxidant of the water type (H20). The index of the obtained layer is around 1.9. Its square resistance is around 50 ohms.

In the preceding example 1, the coated substrate 1 placed in double glazing so that the coating is on the face 1 (with another substrate not coated, but of the same nature and dimensions as the substrate 1 by means of an air bag of 12 mm) has a color purity value in the reflection of 26% and a color purity value in the transmission of 6, 8%. In this example 2, the purity of color in the reflection (in the golden reflections) is not more than 3.6% and is 1.1% in the transmission. Thus, the sub-layer of Sn02: F allows to confer to the substrate anti-static properties due to its electrical conductivity. The sublayer also has a favorable influence on the colorimetry of the substrate, making its coloration clearly more "neutral", both in the transmission and in the reflection; coloration that is caused by the presence of the coating 3, of titanium oxide and that has a relatively high refractive index. It can be polarized by equipping it with a power supply, adapted, to limit the accumulation of lint of relatively important size, of the order of one millimeter. In addition, this sublayer decreases the diffusion of the alkalies towards the photic layer ocat alí tica titanium dioxide Ti02. The alicatic photic activity is then improved.

EXAMPLE 3 Example 2 is repeated, but this time between the substrate 1 and the coating 3 a layer 2 based on silicon oxycarbide, with an index of about 1.75 and a thickness of about 50 nm, which layer can be obtained by CVD a from a mixture of SiH4 and ethylene in nitrogen dilution, as described in the application of EP-A-0 518 755. This layer is particularly effective to prevent the tendency to the diffusion of alkalis (Na +, K +) and of alkaline earths (Ca + +) that come from the substrate 1 towards the coating 3 and therefore the photocatalytic activity is clearly improved. By having, like Sn02: F, an intermediate refractive index between that of the substrate (1.52) and of the coating 3 (around 2.30 to 2.35), it also makes it possible to attenuate the intensity of the substrate coloration. in the reflection as in the transmission and globally decrease the value of the luminous reflection RL of said substrate. Examples 4 to 7 that follow refer to precipitates by CVD.

EXAMPLES 4 TO 7 EXAMPLE 4 This example concerns the CVD precipitate of the coating 3 directly on the substrate 1, with the aid of a standard tube as represented in the application of precipitated EP-A-0 518 755. As precursors, either a metallic organ or a metal halide is used. The tet ra-isopropilat or titanium, which is interesting due to its high volatility and its wide range of use temperatures, from 300 to 650 ° C, was chosen here as the metallic organ. The precipitate is carried out in this example at around 425 ° C, the thickness of the titanium dioxide (Ti02) is 15 nm.

Tetra-ethoxy titanium Ti (0-Et) may also be convenient, and as halogenide, TiCl 4 may be mentioned.

EXAMPLE 5 It is carried out in a manner similar to Example 4, except that here the 15nm layer of titanium dioxide (Ti02) is precipitated not directly on the glass but on a 50nm SiOC sublayer precipitated as in Example 3.

EXAMPLE 6 It is carried out as in Example 4, except that here the thickness of the layer of titanium dioxide (Ti02) is 65 nm.

EXAMPLE 7 It is carried out as in Example 5, except that here the thickness of the titanium dioxide layer is 60nm.

From these examples 4 to 7, it can be verified that the substrates thus coated have a good mechanical resistance to abrasion tests. In particular, no thinning of the Ti02 titanium dioxide layer is observed.

EXAMPLE 8 This example uses a technique associated with the soil-gel that uses a mode of precipitate by "immersion" still called "dip-coating", whose principle comes from Figure 2: it involves submerging the substrate 1 in the liquid solution 4, which contains the appropriate precursor (s) of the coating 3, then remove the substrate 1 therefrom at controlled speed with the aid of a motor instrument 5. The selection of the extraction speed allows adjusting the thickness of the solution that must remain in the surface of the two faces of the substrate and, in fact, the thickness of the precipitated coatings, after the thermal treatment of the latter to simultaneously evaporate the solvent and decompose the precursor (s) in oxide.

A solution 4 comprising either t and titanium rabutoxide Ti (0-Bu) stabilized with the diethylamine DEA in molar ratio 1: 1 in an ethanol solvent of 0.2 mole of tet rabutoxide is used to precipitate the coating 3. per liter of ethanol, or either the mixture of precursors and solvents described in example 1. (Another precursor can also be used, such as titanium dibutoxy-diethanolamine).

Substrates 1 may contain SiOC sublayers. After the extraction of each of the solutions 4, the substrates 1 are heated 1 hour at 100 ° C, then around 3 hours at 550 ° C, with a progressive rise in temperature.

A coating 3 is obtained on each of the faces. In both cases the layers are of titanium dioxide well crystallized in anatase form.

EXAMPLE 9 This example uses the technique called "cell-coating" of which the principle is recalled in figure 3. It consists in forming a narrow cavity delimited by two visibly parallel faces 6, 7 and two joints 8, 9; at least one of these faces 6, 7 will be constituted by the face of the substrate 1 to be treated. Then the cavity of solution 4 is filled with precursor (s) or precursors of the coating, and solution 4 is removed in a controlled manner, so as to form a meniscus by impregnation, with the aid of a peristaltic pump 10 for example, leaving a film of solution 4 on the face of substrate 1 as the solution is removed.

The cavity 5 is then held at least the time necessary for drying. The hardening of the film is effected by heat treatment. The advantage of this technique in relation to dip-coating is in particular that only one of the two faces of the substrate 1 can be treated, and not necessarily both, unless a coating system can be used. The substrates 1 contains films 2 based on silicon oxycarbide SiOC.

Example 6 uses respectively the solutions 4 described in Example 8. The same thermal treatments are then operated to obtain coating 3 of titanium dioxide (Ti02).

The coating has a good mechanical durability.

A field effect appears in the MEB (scanning electron microscope) in the form of monocris "grains" with a diameter of around 30 nm. The roughness of this coating favors the impregnation properties to be reinforced in relation to a non-rough coating. These same solutions 4 can also be used to precipitate coatings by "spray-coating", as shown in Figure 4, where solution 4 is sprayed in the form of a cloud onto the static substrate 1, or by laminar impregnation as depicted in figure 5. In the latter case, the substrate 1, kept under vacuum, is passed over a support 11 in stainless steel and Teflon above a reservoir 12 containing the solution, a solution in which a cylinder is partially submerged. slit, the set of reservoir 12 and cylinder 14 is then moved along the entire length of substrate 1; the tablet 13 is to avoid a very rapid evaporation of the solvent from the solution 4. For more details on the latter technique, it can advantageously refer to the application of the aforementioned WO-9401598.

Tests have been made with the substrates obtained according to the preceding examples in order to characterize the precipitated coatings and evaluate their best results "anti-spray or mist" and "anti-abrasives". | I Test 1: it is the test of the dew or mist figures. It consists in observing the consequences of the photocat ions and the structure of the coating (cups of the hydroxyl groups, porosity, roughness) in the impregnation. If the surface is photoreactive, the carbonated microimpurities that are deposited on the coating are permanently destroyed, and therefore the surface is hydrophilic ie it is anti-dew or mist. A quantitative evaluation can also be made by abruptly heating the initially coated and cold-stored substrate, or simply exhaling on the substrate and measuring if dew or mist appears, and if so, at what time, then measuring the time it takes for the disappearance of said substrate. dew or mist I | Test 2: this involves evaluating the hydrophilicity and oleophilicity on the surface of the coating 3, compared to those on the surface of a single glass, measuring the contact angles of a drop of water and a drop of DOP (dioctyl- phthalate) on their surfaces, after having left the substrates for a week in the ambient atmosphere under natural light, in the dark and after having subjected them for 20 minutes to a UVA radiation.

Test 3: it consists in precipitating in the substrate to evaluate a layer of an organosilane and irradiate it with U.V.A. to degrade it by fot ocat ális i s. The organosilane, which modifies the impregnation properties and the mediates of the contact angle with the water of the substrate, in the course of the irradiation indicate the state of the degradation of the implanted plate. The rate of disappearance of this layer is related to the photic activity of the substrate.

The implanted organosilane is a riclorosilane t: the octilizer riclorosilane (OTS). The implantation is done by immersion.

The apparatus for the test consists of a carousel that rotates around 1 to 6 lamps U.V.A. of low pressure. The samples to be evaluated are placed on the carrousel, the face to be evaluated on the side of the U.V.A. Depending on its position and the number of lamps lit, each sample receives a U.V.A. which varies 2 2 between 0.5 μm, and 50 μm. For examples 1, 2, 3, 8 and 9, the radiation power is selected from 1.8 W / m2, and for Examples 4 to 7 from 0.6 W / m2.

The times between each measurement of the contact angle vary between 20 minutes and 3 hours, depending on the photocatalytic activity of the sample considered. The measurements are made with the help of a goniometer.

Before the radiation, the glasses present an angle of around 100 °. It is considered that the layer is destroyed after radiation when the angle is less than 20 °.

Each sample tested is characterized by the average speed of disappearance of the layer, given in nanometers per hour, ie the thickness of the layer of precipitated organosilane divided by the duration of radiation that allows reaching a final plateau below 20 ° (time of disappearance of the organosilane layer).

All the preceding examples had good results in test 1, ie when exhaled on the coated substrates of the coating, they remain perfectly transparent, while a very visible mist or spray layer is deposited on the uncoated substrates.

The examples were subjected to test 2: the coated substrates, after exposure to UVA rays, have a contact angle with water and with a DOP of at least 5o. On the contrary, a simple glass in the same conditions has a contact angle with water of 40 ° and a contact angle with the DOP of 20 °.

The table below groups the results of the coated substrates according to the preceding examples in test 3. simple glass From the table, it can be verified that the presence of sublayers, especially SiOC, favors the photoalkal activity of the coating containing Ti02 titanium dioxide, due to its barrier effect against the alkalis and alklineot erreos that can migrate the glass ( comparison of examples 4 and 5 or 6 and 7).

It is noted that the thickness of the titanium dioxide-containing coating also comes into play (comparison of examples 1 and 3): for a coating thickness of titanium dioxide (Ti02) greater than the average size of the monomers or "crystallites" ", you get a better photocatalytic effect.

In fact, it has been observed that titanium dioxide (Ti02) coatings, obtained by CVD, have the most developed crystallization, with crystallite sizes of the order of 20 to 30 nm. It can be seen that the alitic photic activity of example 6 (65nm of titanium dioxide (Ti02)) is clearly superior to that of example 4 (15nm of titanium dioxide (TiO2) only). It is then advantageous to provide a thickness of the coating of titanium dioxide (Ti02) at least twice the average diameter of the crystallites it contains. Alternatively, as in the case of example 5, a thin thickness of the titanium dioxide (TiO2) coating can be retained, but choose to use a sub-layer of suitable nature and thickness to favor as much as possible the crystalline expansion of titanium dioxide ( Ti02) from the "first" layer of crystallites.

It can be seen that the crystallization of titanium dioxide (Ti02) was slightly less developed for coatings precipitated by another technique than CVD. Here too, everything is a matter of compromise: less developed crystallization and photochemical activity, a priori less elevated, can be "compensated" by the use of a less expensive or less complex precipitation process, for example. In addition, the use of an appropriate sub-layer or the excitation of titanium dioxide can allow to improve the photocatalytic performances if necessary. From the comparison of examples 2 and 3, it is also found that the nature of the sublayer influences the crystallization mode and, in fact, the photochemical activity of the condensation.

Claims (24)

1. The substrate (1) with a glass, ceramic or vitreous ceramic base, provided on at least a part of at least one of its faces of a coating (3) with alchemical photic or cat property, of a thickness comprised between 5 and 50 nanometers , containing at least partially crystallized titanium oxide obtained by a pyrolysis technique from at least one precursor of organo-metallic type or metal halide.

2. The substrate (1) according to claim 1, characterized in that the crystallized titanium oxide is in anatase form, in rutile form or in the form of a mixture of anatase and rutile.

3. The substrate (1) according to claim 1 or claim 2, characterized in that the titanium oxide is crystallized with a crystallization rate of at least 25%, especially between 30 and 80%.

4. The substrate (1) according to one of the preceding claims, characterized in that the crystallized titanium oxide is in the form of medium-sized crystallites between 0.5 and 60 nm, preferably between 1 and 50, especially between 10 and 40 n.

5. The substrate (1) according to one of the preceding claims, characterized in that the coating 3 also contains a mineral material, in particular in the form of an oxide or mixture of amorphous or partially crystallized oxides of the silicon oxide, titanium oxide, oxide tin, zirconium oxide, aluminum oxide.

6. The substrate (1) according to one of the preceding claims, characterized in that the coating contains additives capable of expanding the absorption phenomenon of the coating and / or increasing the number of charge carriers by exciting the crystal lattice of the oxide or by exciting the coating surface and / or increase the yield and kinetics of the photocatalyst reactions covering at least a part of the coating with a catalyst.

7. The substrate (1) according to claim 6, characterized in that the crystalline network of the titanium oxide is excited, in particular by at least one of the metallic elements of the group comprising the niobium, tantalum, iron, bismuth, cobalt, nickel, copper , ruthenium, cerium, molybdenum.

8. The substrate (1) according to claim 6, characterized in that the titanium oxide or the coating 3 as a whole, is coated with a catalyst, especially in the form of a noble metal film of the platinum, rhodium, silver, palladium type. .

9. The substrate (1) according to claim 6, characterized in that the coating incorporates metallic elements, especially in the form of particles, seeking to increase its absorption band, elements chosen among tin, cadmium, tungsten, cerium, or zirconium .

10. The substrate (1) according to claim 6, characterized in that the excitation of the surface of the titanium oxide or of the coating containing it is carried out by coating at least a part of said coating with an oxide layer or with metal salts. The metal is chosen from iron, copper, ruthenium, cerium, molybdenum, bismuth, vanadium.

11. The substrate (1) according to one of the preceding claims, characterized in that the surface of the coating 3 is hydrophilic, in particular with a contact angle with water of less than 5 ° after being exposed to a light radiation, and / or oleophilic.

12. The substrate (1) according to one of the preceding claims, characterized in that the RMS roughness of the coating (3) is between 2 and 20 nm, in particular between 5 and 20 nm.

13. The substrate (1) according to one of the preceding claims, characterized in that it is arranged under the coating 3 with a photocatalytic layer, at least one film (2) with antistatic, thermal, optical or barrier function before the migration of the alkalis. that come from the substrate (1).

14. The substrate (1) according to claim 13, characterized in that the film (2) with static function, optionally with controlled polarization function, and / or thermal and / or optical is based on a conductive material of the metal or oxide type Excited metal such as ITO, Sn02: F, ZnO: F, ZnO: Al, ZnO: Sn or metal oxide subsitute oxygen in the form of Sn02-x or Zn02.x with X < 2.

15. The substrate (1) according to claim 13, characterized in that the film (2) with optical function is based on an oxide or a mixture of oxides whose index of refractions is intermediate between that of the coating and that of the substrate, especially when they are chosen from the following oxides: A1203, Sn02, ln203, oxycarbide or silicon oxynitride.

16. The substrate (1) according to claim 13, characterized in that the film (2) with barrier function between the alkalis is based on oxide, nitride, oxynitride or silicon oxycarbide, A1203: F or aluminum nitride .

17. The substrate (1) according to claim 13, characterized in that the coating (3) constitutes the last layer of an antireflection layer overlay.

18. The stained glass window "anti-scratch and / or anti-scratch or fog" is monolithic, multiple of the double glazing type or with several glass sheets incorporating the substrate (1) according to one of the preceding claims.

19. The application of the substrate 1, according to one of the claims 1 to 17, to the manufacture of "self-cleaning", anti-dew or vapor and / or anti-waste, of the type of organic and / or mineral residues especially to stained-glass windows for constructions of the double-glazed type, stained-glass windows for windshield-type vehicles, medallion or sides of automobiles, trains, airplanes or stained-glass windows for businesses such as aquarium glasses, showcases, greenhouses, for interior furnishing, for urban furniture, or for mirrors , television screens, electrically controlled variable absorption windows.

20. The process for obtaining the substrate (1) according to one of claims 1 to 17, characterized in that the coating (3) is precipitated with photocatalytic property by pyrolysis in liquid phase, especially from a solution comprising at least one precursor organo-metallic titanium of the chelate type of titanium and / or titanium alcoholate.

21. The process for obtaining the substrate (1) according to one of claims 1 to 17, characterized in that the coating (3) is precipitated with an alkylated photic property with a soil-gel technique, with a precipitate mode of the immersion type or dip-coating, cell-coating, spray-coat ing, or sheet impregnation from a solution comprising at least one organo-metallic titanium precursor of the titanium alcoholate type.

22. The process for obtaining the substrate (1) according to one of claims 1 to 17, characterized in that the coating (3) with an aliphatic fot ocat property is precipitated by vapor phase pyrolysis, CVD, from at least one titanium precursor of the halide or organ-metallic type.

23. The process according to one of claims 20 to 22, characterized in that the coating (3) is precipitated with an aliphatic photic property in at least two successive stages.

24. The process according to one of claims 22 to 23, characterized in that the coating (3) is subjected to an alkylated photic property, after the precipitate at least one heat treatment of the annealed type.