Method for applying a porous antireflection coating and glass with antireflection coating

Field of the Invention

The invention relates to a process for assembling a porous antireflection layer, as well as a glass with an antireflection coating. In particular, the invention relates to an anti-reflective glass for solar applications.

Background of the Invention

Anti-reflective glasses for solar applications are known.

It is particularly known to apply porous antireflection. A method for applying porous antireflection coatings, for example, in German Offenlegungsschrift<patcit id="pcit0001" dnum="DE102005007825A1"><text>DE 10 2005 007825 A1</text></patcit> described. When such a porous antireflection coatings, there is a mixture of the coating material and air, whereby the effective refractive index of the coating is reduced.

The <patcit id="pcit0002" dnum="US20070017567A1"><text>US2007 / 0017567 A1</text></patcit> describes self-cleaning surfaces, inter alia, to solar modules. The photocatalytically active components are embedded in a matrix. The layers have thicknesses of 200 nm. In these areas, TiO₂Layers visually striking. Layers show from 20 nm an intrinsic color (only yellow then red, blue and green) and from 5 nm reflection in the solar spectrum. Moreover, the effect of photocatalytic materials through the incorporation into the matrix is ​​very limited, so that only show the top of the layer protruding particles activity. The matrix components listed include organic ingredients which are degraded by photocatalysis. On the designated scattering layers (albedo surfaces) occurring in such cases, calcification may not be noticeable on solar panels caused by chalking However scattering centers, reduce the transmission.

It is also known to apply such porous antireflection coatings with a sol-gel process.

The requirements for anti-reflective coatings for solar glass, in particular for photovoltaic applications are high. So the glass is to have high transmission possible over the entire range of visible light and near-infrared range. The anti-reflection layer should have a low refractive index as possible.

At the same time, the anti-reflection layer to be weather resistant for decades. Also on the abrasion resistance of such antireflection high demands.

It has been found that conventional porous antireflection coatings can pollute relatively easily, resulting in loss of transmission. Frequent cleaning of the antireflection coatings may in turn cause damage to the layer and thus also to a reduction in transmission.

For architectural glass lenses are known which comprise a titanium oxide coating. Due to the photo-catalytic action of titanium oxide or titanium dioxide leads to a self-cleaning effect of the glass. Such glasses are also known as self-cleaning glass.

Due to the high refractive index of titanium oxide and the associated transmission losses self-cleaning glass produced are not particularly well suited for solar applications because performance degradation by the reflecting titanium oxide layer occur by conventional methods.

Object of the invention

The invention is based on the object of providing a method with which it is possible to provide a self-cleaning antireflection coating, which ensures a high transmission.

In particular, it is an object of the invention to provide a self-cleaning antireflection coating with low refractive index.

Another object of the invention is to provide an environmentally resistant, abrasion resistant, self-cleaning coating.

Summary of the Invention

The object of the invention is achieved already by a method for assembling a porous antireflection layer and through a glass for exterior applications, particularly for architectural and solar applications, according to one of the independent claims.

Glass is defined in this invention as a transparent in essence glass, glass ceramic or transparent, as a disc of suitable plastic, such as soda-lime glass, borofloat^®, Solar glasses and more, all glass ceramics, preferably, transparent glass ceramics, as Robax^®, Zerodur^® and further, as well as transparent optical plastics, such as polymethyl methacrylate, Cycloolefinic copolymers, polycarbonate, and others. Preferably, a flat glass is used, but the invention is not limited to sheet-like substrates.

Preferred embodiments and developments of the invention are disclosed in the respective dependent claims.

The invention relates to a process for assembling a porous antireflection layer. The anti-reflection layer is deposited by a sol-gel method.

Surprisingly, it has been shown that the titanium oxide causes no significant deterioration of the optical properties of a porous antireflection layer.

Rather, films of the invention have a comparable refractive index, like other porous antireflection coatings, for example based on silicon oxide particles and Siliziumoxidmatrix, and thus very good antireflection properties at an additional photocatalytic surface.

According to the invention, a titanium-containing precursor is used and it will be added to the sol-gel solution particles, in particular nanoparticles, such as nanoparticulate silicon oxide or silicon dioxide.

In the method according to the invention occurs by the titanium-containing precursor thus for forming a titanium oxide matrix. Preferably, the formed by hydrolysis and condensation matrix consists predominantly after a thermal treatment of amorphous titanium oxide having a Restorganikanteil of 10-50%. About a thermal treatment the residual organics is removed and there is a matrix of crystalline or partly crystalline TiO₂, Preferably in the anatase modification. The crystallite size of the nanoscale crystalline or partly crystalline TiO₂ preferably is between 4 - 35 nm, more preferably between 8 -. 25 nm in the matrix are nanoparticles, in particular silica-nanoparticles embedded. The matrix-forming titanium oxide preferably has a micro and mesoporosity of 1 - to 25%.

The synthesis guide present invention is achieved in that the matrix-forming TiO₂ only between and / or on the SiO₂Particles has formed. This ensures that the accessible surface of photocatalytic TiO₂ is large, with low mass fraction or volume fraction of TiO₂ in the layer. Hereby is achieved that despite the high refractive index of TiO₂ the refractive index of the amorphous-crystalline layer composite is low.

It has been found, that for example in contrast to methods that will be added in which titanium dioxide in particulate form, in particular in the form of crystalline nano-particles, the optical properties when prepared by the process of the present invention layers with respect to a coating which is prepared with a silicon-containing precursor , only slightly change.

Thus it has been possible with the method according to the invention to produce an antireflection coating having a refractive index of less than 1.38, preferably less than 1.34, and particularly preferably of less than 1.30.

The the antireflection coating is preferably a single-layer antireflection coating, which, in contrast to rotating shift systems, due to their refractive index has a non-reflective and at no wavelength increases the reflection of the composite material. The anti-reflection layer is formed as a broadband antireflection coating.

In a preferred embodiment of the invention, the particles, particularly nanoparticles, a refractive index less than / equal to 1.7, preferably less than / equal to 1.6, and more preferably less than / equal to 1.55.

This includes a provided with an antireflection coating according to the invention of glass to a high transmission. In particular, a glass could be provided having the entire wavelength range between 450 and 800 nm has a transmission of at least 85%, preferably of at least 90% and particularly preferably of at least 95%.

It has further been found that even a relatively small proportion of titanium oxide throughout the layer, in particular of less than 40, preferably less than 20 and more preferably less than 15 weight% is sufficient for an adequate self-cleaning effect.

In particular, a Thus, l-gel solution used, in which the ratio of particles to precursor between 0.1 and 0.9 preferably 0.7 and 0.8, wherein the ratio on a weight -% - base is calculated.

In particular, a glass is provided by the invention, in which the added particles of at least 60, preferably occupy at least 70 and particularly preferably at least 80% by weight of the finished anti-reflection layer.

In particular, a glass is provided by the invention, wherein, in the anti-reflection layer according to the invention has a porosity (open porosity) between 20 and 40% by volume is present. Characterized in that the pores are filled with air, the desired refractive index is achieved.

Particularly suitable nanoparticles have a size between 1 and 100 nm, preferably 3 and 70 nanometers, more preferably in the range of 6 - proven 30nm.

The particles are preferably formed of glass, glass ceramic or ceramic. With such nanoparticles a high transparency of the film can be achieved.

In one embodiment of the invention different sized nanoscale particles in the coating solution, preferably SiO₂Particles are. It is especially provided particles add in at least two different size fractions. Also, silicon alkoxides of the empirical formula Si (OR)₄, RSi (OR)₃ (R = methyl, ethyl, phenyl) be a constituent of the coating solution.

The precursor may, for example, a titanium halide, a titanium nitrate, titanium sulfate and / or a tetraalkyl titanate (titanium tetraalkoxide) include. In particular, titanium tetraethylate and titanium tetrapropylate is provided as a precursor.

To the amorphous titanium-containing TiO₂- Precursor in combination with an aqueous dispersion nanokolloiddisperser SiO₂to be able to keep particles stably in solution is used in a preferred embodiment of the invention, a hydrolysis-stabilized titanium-containing precursor.

In sol-synthesis of the present invention, therefore, the titanium precursor is first reacted with a complex ligand. As complex ligands such as ethyl acetoacetate, 2,4-pentanedione (acetylacetone), 3,5-heptanedione, the 4,6-nonanedione or 3-methyl-2,4-pentanedione (2-methylacetylacetone), triethanolamine, diethanolamine, ethanolamine , 1,3-propanediol, 1,5-pentanediol, carboxylic acids such as acetic acid, propionic acid, ethoxyacetic acid, methoxyacetic acid, polyether carboxylic acids (eg ethoxyethoxyacetic acid) citric acid, lactic acid, methyl acrylic acid, acrylic acid.

The molar ratio of complexing ligand to titanium precursor is preferably from 5 to 0.1, more preferably from 2 to 0.6, particularly preferably 1.2 to 0.8.

The particles are not so limited their particle size distribution. In order to achieve the best possible distribution of particles, of different sizes are used in one preferred embodiment, particle mixtures. Particularly preferred are mixtures in which a smaller particle distribution fills the gaps greater.

In a preferred embodiment of the invention, the anti-reflection layer micropores or mesopores, in particular open pores having an average pore diameter of 1 to 12 nm, preferably 3-8 nm. The pore diameter can be determined for example with the known in the art method of ellipsometric porosimetry, where H₂O is used as sorptive. In this method, the change of the refractive index of a layer depending on the relative humidity is determined. For the determination of the pore diameter The adsorption isotherm is used and the evaluation is performed according to a modified known to those skilled Kelvin equation. It is preferable that in the pores to stochastic bottleneck pores. In a particular embodiment, it may also be pores having a rod-shaped geometry instead.

In a preferred embodiment of the invention the titanium-containing precursor contains a hydrolysis-stabilized, water-soluble, amorphous titanium complex of titanium halides, titanium nitrates, titanium sulfates and / or tetraalkyl titanate, especially titanium tetraethylate and titanium propylate.

After the reaction with the complex ligands, in order to achieve a better hydrolytic stability of the titanium precursor, or a controlled hydrolysis be performed.

Preferably, the particles are inorganic materials present in amorphous or crystalline or partially crystalline.

The particles are not so limited their shape, so they can, for example, round, plate-like, cylindrical, fibrous, rectangular, cubic and have other possible forms.

The molar ratio of water to titanium precursor amounts to 10 to 0.1, preferably 7-3, particularly preferably 6 - 4. In a particular embodiment, the hydrolysis can be carried out under acidic conditions. These are preferably the hydrolysis for example mineral acids such as HNO₃, HCl, H₂SO₄ or organic acids such as ethoxyacetic acid, methoxyacetic acid, polyether carboxylic acids (eg ethoxyethoxyacetic acid) citric acid, paratoluenesulfonic acid, lactic acid, methyl acrylic acid, acrylic acid added.

In a preferred embodiment, the solvent of the reaction mixture after reaction of the titanium precursor removed under reduced pressure with the complex ligand and subsequent hydrolysis. It is a hydrolysis-stable, in polar (H₂O, ethanol, n-propanol) and nonpolar (toluene) solvents obtained again soluble precursor powder.

Another way to remove the solvent, to recover a return-soluble titanium oxide precursor powder is spray drying the reaction mixture.

The amorphous water-soluble precursor powders used to doping in an amount of &lt;10 mol%, based on transition metal oxides. The doping can be added before or after the reaction of the titanium alcoholate with the polar complexing and chelating compound. Examples of suitable dopants are Fe, Mo, Ru, Os, Re, V, Rh, Nd, Pd, Pt, Sn, W, Sb, Ag and Co. These can be in the form of their salts to the synthetic approach or the medium in appropriate stoichiometry be added.

In a preferred embodiment, the sol-gel solution is applied by a dipping process or by means of roll coating. In addition, all other customary for liquid coatings application methods are used, such as spin coating, spraying, slot casting, flooding and brushing.

The dipping method is particularly suitable for uniform coating on both sides of large glass substrates.

The roll-coating method has the advantage that a coating in a plant inline one or both sides can and no large pools must be provided over the dipping process. Moreover, the coating is very rapid in this case, so that high flow rates are possible.

In a preferred embodiment of the invention, the anti-reflection layer at a temperature between 300 and 1000 ° C, preferably 450-700 ° C, sintered particularly preferably between 500 and 700 ° C baked respectively. These are preferably organic compounds, which have been formed from the sol, substantially removed.

The resulting layer contained mostly particles, such as silica particles, which are in a matrix consisting of at least partially crystalline titanium oxide, embedded.

The step of baking may in particular, as is provided in a further preferred embodiment of the invention, carried out during a biasing process or the tempering process directly upstream branding.

So no additional operation for the baking of the antireflection coating is required and it can not lead to a reduction in the bias of an already tempered glass during subsequent baking an antireflection coating. It is advantageous that the applied by a sol-gel process layer already has sufficient strength for subsequent processing.

It should also be possible to subject the coating in a first step of thermal curing at lower temprature, where the layer is not heated to such a high temperature that removes the organic components to a large extent. This provides a useful intermediate for biasing with a mechanically resistant anti-reflection layer is provided.

The particles are preferably added as a suspension of the sol-gel coating solution.

In a variant of the invention are SiO₂Particles produced through the Stöber process. The particles can be either dense, microporous or mesoporous. The morphology of the particles can be both spherical and irregular nature.

To increase the abrasion resistance of the layers, even aluminum in the form of alkoxides, Alumiuniumsalzen, complexes of alkoxides with ethyl acetate or AlOOH can be added in a particular embodiment, the coating solution. As complex ligands such as ethyl acetoacetate, 2,4-pentanedione (acetylacetone), 3,5-heptanedione, the 4,6-nonanedione or 3-methyl-2,4-pentanedione (2-methylacetylacetone), triethanolamine, diethanolamine, ethanolamine , 1,3-propanediol, 1,5-pentanediol, carboxylic acids such as acetic acid, propionic acid, ethoxyacetic acid, methoxyacetic acid, polyether carboxylic acids (eg ethoxyethoxyacetic acid) citric acid, lactic acid, methyl acrylic acid, acrylic acid.

In one development of the invention, in addition to silicon and aluminum-containing oxides already mentioned other semi-metal or metal oxides such as boron oxide, zirconium oxide, cerium oxide, and zinc compounds form part of the titanium-containing matrix.

In one development of the invention, the association of the nanoparticulate component with the matrix-forming titanium precursor in the acidic medium is carried out, in particular at a pH value below 3, preferably below 2.5, and more preferably below 1.5.

It has been found that the combination of matrix-forming titanium precursors and nanokolloiddispersen nanoparticles such as SiO₂to adherent particles after firing and abrasion resistant layers results.

In one development of the invention, an anti-corrosion layer, for reducing or preventing the corrosion of the glass is applied between the substrate and the antireflection layer that is a layer that the direct contact of water or H⁺Ions with alkalis of the substrate glass prevented.

On a substrate, especially a glass substrate, that is a first layer is first applied, to which then the anti-reflection layer is applied.

It has been found that there is by water in the porous anti-reflection layer for leaching, especially used for architectural and solar applications soda-lime glasses. The leaching of alkali metal ions, especially of sodium leads to glass corrosion, which causes cloudiness of the glass, the decomposition of the glass matrix and a breaking of the antireflection coating.

The inventors have found that such glass corrosion processes can be effectively prevented by an intermediate layer, which either prevents water from coming or prevents alkali ions, especially sodium ions diffuse from the glass into the antireflection coating to the substrate glass into contact.

By this barrier layer and the associated ligature of the ion diffusion is further prevented that the photocatalytic activity by ion diffusion processes out of the glass in the TiO₂ may be impaired. The anti-corrosion layer, the combination of a self-cleaning layer, based on the photocatalytic effect of TiO₂, Possible on soda-lime glass.

The anticorrosive coating may for example be applied as a dense silicon oxide layer.

To apply the corrosion protection layer are various methods, in particular the layer can be applied by flame pyrolysis or be deposited by means of a PVD or CVD process. Also, the use of a dense sol-gel layer has been found to be useful. Especially advantageous is the use of a dense silicon-titanium mixed oxide layer having approximately the same refractive index as the substrate glass. It can for example be made thick without the optical properties of the overlying antireflective disturbing. The corrosion protection and barrier effect is therefore particularly pronounced in this case.

Another possibility for providing a corrosion protective layer is the leaching of the glass substrate, for example by means of a plasma treatment, by means of the alkali and / or Erdalkalibestandteile may be removed in the surface region having a relatively good selectivity.

Good corrosion protective effect is given in the context of the invention, if the diffusion of alkalis according to the DIN 52296 test or water to at least 30%, preferably 50%, particularly preferably 75% is reduced.

The invention further relates to a glass, especially for outdoor use, in particular a glass for solar applications.

The glass is preferably made by a process according to the invention, comprises a glass substrate and a deposited on the glass substrate by a sol-gel process titanium oxide porous antireflection layer.

In particular, the glass comprises a layer in which particles, especially nanoparticles, such as silica particles, are embedded in a matrix comprising formed by a sol-gel titanium oxide, in particular essentially consists of titanium oxide.

Preferably, the anti-reflection layer comprises silicon oxide particles with a size between 1 and 100 nm, preferably 3 and 70 nanometers, preferably in the range 6-30 nanometers.

Preferably, the particles comprise at least 50, more preferably at least 70% by weight silicon oxide. With particles consisting mainly of silicon oxide, is low refractive indices can be achieved. Next silicon oxide is particularly resistant to chemical attacks and environmental influences.

As the glass substrate is preferably an alkali glass, in particular using a soda-lime glass. Such glasses are inexpensive and have a high transparency. In a particular embodiment, low-iron, is UVabsorbierendes solar glass used.

The glass of the invention is particularly useful in outdoor applications as part of a housing for a solar module, a solar receiver or as a front panel, as well as architectural glazing.

It has been found that under UV radiation exposure layers of the invention show a self-cleaning effect. This self-cleaning effect on the photocatalytic activity of the TiO₂ due in the anatase modification.

In a particular embodiment of the invention is the photocatalytic activity of the TiO₂ detectable even under irradiation of light in the visible wavelength range of light.

In a preferred embodiment, the anti-reflection layer is applied to a glass tube, which is part of a photovoltaic module, in particular part of a CIGSbasierten photovoltaic module. Preferably the Entspiegelungschicht also has self-cleaning properties. The construction of such Photovolatikmoduls example from inside to outside structured as follows: In the center, a groundbreaking value custom solution or oil (immersion solution or oil) is followed by the inner tube of glass that preferably glasses contained soda-lime glass or other sodium is. The thermal elongation of the inner tube is adapted to that of the absorber layer, in this case, a CIGS layer, layer of the solar system and is between 7.5 * 10^-6 K^-1 and 11 * 10^-6 K^-1, Preferably between 8.5 * 10^-6 K^-1 and 10 * 10^-6 K^-1,

The solar layer system from the inside out be structured as follows: inner tube / barrier (SiN; optional) / molybdenum / absorber layer (CIGS) / buffer layer (CdS) / window layer (ZnO). The entire layer structure is thick in one preferred embodiment, 3-4 microns. The outermost layer is preferably Acrylatrohr separated by the or the immersion solution or oil described above from a polymer tube, due to the high transmission that in turn is separated from the outer tube by the immersion solution or oil. The outer tube is made of glass and preferably should have a similar thermal expansion coefficient as the inner tube. It is, each glass having a sufficiently high transmission having conceivable, preferred are soda lime, aluminosilicate, and Borofloat glass. The outside of the glass tube is provided with the self-cleaning anti-reflection coating. In a particular embodiment, is applied under the self-cleaning antireflection coating a corrosion barrier layer, in particular deposited.

In another embodiment, the self-cleaning antireflection coating is applied on a planar CIGS photovoltaic module.

The preferably self-cleaning antireflection coating can be used on any solar application to use and with respect to the solar absorber layers and systems not limited.

The glass according to the invention, in particular for solar applications, preferably comprises a flat glass substrate or a tubular substrate and a deposited by a sol-gel method titania-containing porous antireflection layer. However, the invention is in principle not limited to the shape of the coated glass substrate, so that any shape of glass substrates can be coated.

In order to produce layer systems according to the following general synthesis route was used in one embodiment:

There were 110 g of ethanol with 50 g HNO₃ (1 mol / l) with X g of an aqueous dispersion of nanoscale SiO₂submitted particles (the components X and Y are defined in the following table). To this solution Y g of an amorphous hydrolysis-stabilized titanium oxide precursors were added dissolved in 40 g of ethanol. With the inventive coating solutions thus prepared can with a Zugschwindligkeit of 10-20 cm / min via the dip-coating method, at a relative humidity of 30% and a firing temperature of 450 ° C - 700 ° C layers according to the invention are prepared.

Amorphous hydrolysis-stabilized titanium oxide precursors were prepared according to the following synthesis:

Precursor A:

For this purpose, 1.0 mol of titanium (IV), for example ethoxide solution while stirring 1.0 mole acetylacetone within about 25 minutes, with a significant warming begins. The lemon-yellow solution is stirred for 45 min at room temperature and then hydrolyzed with 5 moles of water. The solvent and other volatile components are removed under vacuum at 80 ° C and 40 mbar. The powder is then dried for 4 hours at 125 ° C. A fine yellow precursor powder with an oxide content of approximately 56 wt .-%.

Precursor B:

For this purpose, 1.0 mol of titanium (IV) propylate solution, while stirring, for example 1.2 mol ethoxyacetic added dropwise within about 25 minutes, during which significant warming began. The lemon-yellow solution is stirred for 45 min at room temperature and then hydrolyzed with 5 moles of water. The solvent and other volatile components are removed under vacuum at 80 ° C and 40 mbar. This gives a gel with an oxide content of about 50 wt .-%.

The overview of the variants of the invention are shown in the following table:<tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="3"><colspec colnum="1" colname="col1" colwidth="21mm" /><colspec colnum="2" colname="col2" colwidth="107mm" /><colspec colnum="3" colname="col3" colwidth="38mm" /><thead><row><entry valign="top">Solvariante</entry><entry valign="top">X (nanoparticle component)</entry><entry valign="top">Y (titanium oxide precursors)</entry></row></thead><tbody><row><entry>I</entry><entry>125 g of 30% strength aqueous dispersion of 8 nm SiO₂particles</entry><entry>A - 4.1 g</entry></row><row><entry>II</entry><entry>100 g of 30% aqueous dispersion of 8 nm SiO₂Particles 15 g, 50% strength aqueous dispersion of 55 nm diameter SiO₂particles</entry><entry>A - 4.5 g</entry></row><row><entry>III</entry><entry>125 g, 30% strength aqueous dispersion of 15 nm diameter SiO₂particles</entry><entry>A - 4.5 g</entry></row><row><entry>IV</entry><entry>125 g aqueous dispersion of 8 nm SiO₂particles</entry><entry>B - 6.1 g</entry></row><row><entry>V</entry><entry>125 g, 30% strength aqueous dispersion of 15 nm diameter SiO₂particles</entry><entry>B - 7.3 g</entry></row></tbody></tgroup></table></tables>

The self-cleaning effect was tested as follows:

The studies were carried out inter alia on the basis of DIN draft "DIN 52980 Photocatalytic activity of surfaces" as small-scale tests.

For this purpose, three solutions with different concentrations of methylene blue (2x10^-3 mol / l, 2x10^-4 mol / l, 2x10^-5 mol / l) prepared by adding 64 mg, 6.4 mg and 0.64 mg of methylene blue in 100 ml H₂O are dissolved. It drops were applied to the substrates to be measured, and the discoloration by irradiation in a sun test CPS, UV exposure to 270 nm, 250-460 W / m² rated. The results of the photocatalytic degradation of 10^-4 mol / L methylene blue are shown in the following Table 1 below. It has been found that the inventive sample compared to reference substrates and also commercially available photocatalytic, self-cleaning glass is a significant improvement.<tables id="tabl0002" num="0002"><table frame="all"><title>Table 1: Fading of 10^-4 mol / l of methylene blue in the test described above.</title><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="38mm" /><colspec colnum="3" colname="col3" colwidth="40mm" /><colspec colnum="4" colname="col4" colwidth="37mm" /><colspec colnum="5" colname="col5" colwidth="17mm" /><thead><row><entry valign="top">Exposure time [h]</entry><entry valign="top">Reference (uncoated)</entry><entry valign="top">Reference (porous Einschichtentspiegelung</entry><entry valign="top">Commercially Photokat. active architectural glass</entry><entry valign="top">sample IV</entry></row></thead><tbody><row><entry align="center">0.5</entry><entry align="center">5</entry><entry align="center">5</entry><entry align="center">4</entry><entry align="center">4</entry></row><row><entry align="center">1</entry><entry align="center">4</entry><entry align="center">5</entry><entry align="center">3</entry><entry align="center">3</entry></row><row><entry align="center">1.5</entry><entry align="center">4</entry><entry align="center">4</entry><entry align="center">3</entry><entry align="center">2</entry></row><row><entry align="center">2</entry><entry align="center">4</entry><entry align="center">4</entry><entry align="center">3</entry><entry align="center">1</entry></row><row><entry align="center">2.5</entry><entry align="center">4</entry><entry align="center">4</entry><entry align="center">3</entry><entry align="center">0</entry></row><row><entry align="center">3</entry><entry align="center">3</entry><entry align="center">4</entry><entry align="center">3</entry><entry align="center">0</entry></row><row><entry align="center">3.5</entry><entry align="center">3</entry><entry align="center">4</entry><entry align="center">3</entry><entry align="center">0</entry></row><row><entry align="center">4</entry><entry align="center">3</entry><entry align="center">4</entry><entry align="center">3</entry><entry align="center">0</entry></row></tbody></tgroup><tgroup cols="5" rowsep="0"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="38mm" /><colspec colnum="3" colname="col3" colwidth="40mm" /><colspec colnum="4" colname="col4" colwidth="37mm" /><colspec colnum="5" colname="col5" colwidth="17mm" /><tbody><row><entry namest="col1" nameend="col5" align="justify">Legend: 0 = no residue to recognize 1 = only very weak residues recognizable 2 = only weak residues recognizable 3 = residues are still visible 4 = residues are still clearly visible 5 = no change, all residues are still visible</entry></row></tbody></tgroup></table></tables>

DESCRIPTION OF THE DRAWINGS

The invention will in the following with reference to the drawings <figref idrefs="f0001">Fig. 1</figref> and <figref idrefs="f0002">FIG. 2</figref> are explained in detail.<dl id="dl0001" compact="compact"><dt>Fig. 1</dt><dd>schematically shows an embodiment of a glass of the invention,</dd><dt>FIG. 2</dt><dd>shows a schematic detailed view of an antireflection coating.</dd></dl>

In <figref idrefs="f0001">Fig. 1</figref> schematically a glass 1 is shown, which comprises a glass substrate 3 and a coating applied by means of a sol-gel method, titanium oxide antireflection second

The anti-reflection layer 2 has in this embodiment, a proportion of titanium dioxide 5-20% and is therefore self-cleaning due to the photocatalytic action of titania. The refractive index is less than 1.34.

Between the anti-reflection layer 2 and the substrate glass 3 a flame pyrolysis deposited dense corrosion protection layer 4 is arranged in this embodiment, which prevents water from flowing into the porous anti-reflection layer 2 to the substrate glass 3 in contact and caused so glass corrosion in the substrate glass. 3

<figref idrefs="f0002">FIG. 2</figref> shown schematically shows a detailed view of an anti-reflection layer 2. The anti-reflection layer 2 includes a group formed by a sol-gel process matrix 5 of titanium dioxide, which is embedded in particulate silicon. 6

The anti-reflection layer, for example, be prepared as follows:

There are (IV) dropped example to 0.1 mol of titanium butoxide solution with stirring 0.1 mol acetylacetonate. According to the following dropwise addition of 0.3 mol H₂O, the solution is stirred (1 h) added and 10 g of 1,5-pentanediol.

To this solution is then, with stirring, 48 g of a 30 wt .-% alcoholic dispersion of SiO₂Nanoparticles in isopropanol added having an average spherical diameter of 10 to 15 nm.

Next is then under stirring 192 g of a 30 wt .-% alcoholic dispersion of SiO₂Nanoparticles in isopropanol having an average spherical diameter of 18 - 30 nm is added. The SiO used₂Particles have a substantially spherical geometry. Subsequently, the solution is diluted with 2400 g of ethanol.

The solution thus prepared can at a tensile speed of 10-30 cm / min through the dip coating method, at a relative humidity &lt;40% and a firing temperature 450-700 ° C mechanically resistant antireflective coatings are produced.

According to a further embodiment, the anti-reflection layer may be prepared as follows:

There are (IV) dropped example to 0.1 mol of titanium butoxide solution with stirring 0.1 mol acetylacetonate. According to the following dropwise addition of 0.3 mol H₂O, the solution is stirred (1 h) added and 10 g of 1,5-pentanediol. To this solution is then stirring 480 g of a 15 wt .-% alcoholic dispersion of SiO₂added nanoparticles in isopropanol. The particles used have an elongated, fiber-like geometry with an average diameter of 10 - 15 nm and a length of 30 -. 150 nm Subsequently, the solution diluted with 2160 g of ethanol.

The solution thus prepared can at a tensile speed of 10-30 cm / min via the dip-coating method, at a relative humidity &lt;40% and a firing temperature from 450 to 700 ° C layers according to the invention are prepared.

By means of the invention was a weather-resistant, self-cleaning glass can be provided which is particularly suitable for solar applications.

It is understood that the invention is not limited to a combination of features described above, but that the skilled person all the features, so far as is reasonable, will combine.

LIST OF REFERENCE NUMBERS

<dl id="dl0002" compact="compact"><dt>1</dt><dd>Glass</dd><dt>2</dt><dd>antireflection</dd><dt>3</dt><dd>substrate glass</dd><dt>4</dt><dd>Anticorrosive coating</dd><dt>5</dt><dd>Titania matrix</dd><dt>6</dt><dd>silica particles</dd></dl>