Process of manufacturing self-cleaning window glass or glass building facade involves atomised application of silicon agent to titanium oxide surface

The Invention relates to a process for the production of multilayer systems having photocatalytic properties on surfaces.

PVD - process (Physical Vapor Deposition) such as evaporation and sputtering processes have long been state of the art. Sputtering or (Solid State) referred sputtering the process in which atoms of a material by bombarding with knocked out high-energy noble gas ions from the composite and are deposited on a substrate. To this end, there is a extensive standard literature, from the example, the diode sputtering (K. Wasa, S. Hayakawa: "HANDBOOK OF SPUTTER DEPOSITION TECHNOLOGY: PRINCIPLES, TECHNOLOGY, AND APPLICATIONS "(MATERIALS SCIENCE AND PROCESS TECHNOLOGY SERIES) (1992)) should be mentioned.

Known are also methods in which a fuel or oxy-hydrogen flame organometallic compounds introduced and combustion processes were decomposed and deposited on a bounding surface. These Methods are called flame pyrolysis or Combustion CVD method (US Patent 4,600,390). In Scripture<patcit><text>DE 42 37 921 A1</text></patcit> the flammenpyrolytische Decomposition of organic substances proposed silicon to silicon-containing Coatings on surfaces to realize. Objective of such coatings is to increase the hydrophilicity the surface and the use of the silicon-containing layer as a bonding layer.

Also Prior art coatings with photocatalytic properties, which contain titanium oxide. Common here are mixed layers of titanium oxide and silicon oxide (M. Machida et al .: "THE EFFECT OF 5102 IN ADDITION SUPERHYDROPHILIC PROPERTY OF TIO2 PHOTO CATALYST "; J. of Mat. Sci. 34 (1999) 2569-2574). Applied method of depositing this layer systems Sol-gel or as of the <patcit><text>EP 1254870 A2</text></patcit> to refer, thermal CVD method. is the sol-gel process it. by a wet chemical process This means a large scale an immense effort in terms of space requirements, demand for chemical Substances, dipping and drying sections, etc. The thermal CVD method, as shown in of the <patcit><text>EP 1254870 A2</text></patcit> or described in WO 98/41480, require in turn a high heat transfer in the substrates, which limits their use for many substrates greatly limits. by virtue of the process-related implementation of the thermal CVD method the layer application is tied to the float glass manufacturing process, where during the cooling which for TiO₂-Training Necessary chemical precursors still hot on the glass surfaces are metered.

Of the Invention addresses the problem of specifying a method which the existing disadvantages of the established method for the deposition photocatalytic layers overcomes.

According to the invention this Task in a method for coating substrates with a photocatalytic active layer system achieved in that at least one layer is applied by a flame hydrolysis process, while the other layers preferably by physical vapor deposition getting produced. The essential advantage of the invention is in the combination of flammenpyrolytischer depositing silicon oxide and the subsequent application of the actual photocatalytic Titanium oxide by Festkörperzerstäubung. The Silicon oxide layers serve as a barrier to the Diffusion of alkali ions from the glass substrate into the photocatalytic layer. At the same conditions the internal structure of the flammenpyrolytischen Layers an extremely hydrophilic surface. Another advantage of the Invention is that the entry temperature during manufacture, due to both deposition and flame pyrolysis Festkörperzerstäubung, significantly is lower. The inventively prepared Coating systems are characterized by the fact that by a post-curing the photocatalytic degradation rate can be increased by a multiple.

The Invention will be described in greater detail with reference to embodiments. The drawings show:

<figref idrefs="S9">1</figref> reduction of stearic acid under UV irradiation for inventively produced and marktüb&lt;?page 3?&gt;Liche rehearse

The The method according to the invention is directed to the production of a multilayer system based on SiO_2-x(OH)_2x With x is from 0 to 2 (hereinafter silicon oxide), and titanium oxide. A subsequent thermal treatment of the coating is a function the substrate used to increase the photocatalytic effect possible.

content the inventive solution is the coupling of a silicon oxide layer with a titanium oxide layer. This titanium oxide layer is in this case either directly on the silicon oxide layer or to an additional plurality of Layers existing multilayer system that the silicon oxide layer includes applied. The silicon oxide layer is in this case by flame deposited. The titanium oxide layer is then deposited by Festkörperzerstäubung. For a be flammenpyrolytische deposition of silicon oxide as precursor substances organometallic compounds which silicon contain used.

The Layer thickness of the silicon oxide layer can be 5 to 200 nm, preferably However, 10 to 30 nm, respectively.

The Titanium oxide layer can be at a process temperature of from room temperature up to 500 ° C be deposited. The layer thicknesses of said titanium oxide can be between 5 nm and 300 nm.

A final Heat treatment may be carried out in a temperature range of 0 ° C to 650 ° C. The duration of a Annealing can be between 0 h and be 5 h. Substrates which can be both uncoated and coated materials already used. It may be single layers, but also to multi-layer systems act. The preferred substrate material is glass. Even textiles are suitable as substrates.

furthermore Is it possible produce coating systems with photocatalytic properties, in which both the silicon layer and titanium oxide layer mitttels Festkörperzerstäubung deposited will.

The preferred application of the method lies in the Manufacture of self-cleaning Fensterglas- or masonry coatings.

Application Example 1

parameter for the flammenpyrolytische deposition of silicon oxide: flame pyrolysis plant with a temperature controllable moving table and Brenner <tables><table><tgroup cols="2"><colspec colname="1" colwidth="1*" /><colspec colname="2" colwidth="1*" /><tbody><row><entry colname="1">Precursor / gas mixture:</entry><entry colname="2">Fuel gas mixture with tetramethylsilane</entry></row><row><entry colname="1">Burner:</entry><entry colname="2">hole burner (Width 225 mm)</entry></row><row><entry colname="1">distance Substrate - Brenner:</entry><entry colname="2">5 mm</entry></row><row><entry colname="1">preheating:</entry><entry colname="2">80 ° C</entry></row><row><entry colname="1">Pass Number:</entry><entry colname="2">4</entry></row><row><entry colname="1">Verfahrtischgeschwindigkeit:</entry><entry colname="2">150 mm / s</entry></row><row><entry colname="1">silica Layer thickness:</entry><entry colname="2">25 nm</entry></row></tbody></tgroup></table></tables>

parameter for the Titanium oxide layer deposition by Festkörperzerstäubung: <tables><table><tgroup cols="2"><colspec colname="1" colwidth="1*" /><colspec colname="2" colwidth="1*" /><tbody><row><entry colname="1">DC sputtering:</entry><entry colname="2" /></row><row><entry colname="1">Target Material:</entry><entry colname="2">titanium</entry></row><row><entry colname="1">Process gas:</entry><entry colname="2">argon</entry></row><row><entry colname="1">Reactive gas:</entry><entry colname="2">oxygen</entry></row><row><entry colname="1">distance Target substrate:</entry><entry colname="2">50 mm</entry></row><row><entry colname="1">gas pressure (Argon):</entry><entry colname="2">1.5 x 10^-2 mbar</entry></row><row><entry colname="1">gas pressure (Oxygen):</entry><entry colname="2">0.6 x 10^-2 mbar</entry></row><row><entry colname="1">Sputtering power:</entry><entry colname="2">300 W</entry></row><row><entry colname="1">Tension:</entry><entry colname="2">450 V</entry></row><row><entry colname="1">Presputter time:</entry><entry colname="2">2 min</entry></row><row><entry colname="1">Coating time:</entry><entry colname="2">15 min</entry></row><row><entry colname="1">thickness the TiO_x-Layer:</entry><entry colname="2">137 nm</entry></row></tbody></tgroup></table></tables>

&lt;?page 4?&gt;

Measurement of photocatalytic degradation:

Experimental setup:

The photocatalytic property was on the elimination of stearic acid UV radiation measured. The stearic acid was dissolved in methanol (8.8 x 10^-3 minor) in front. The samples examined masses each 2.5 × 3.8 cm², In each sample, 4 .mu.l of stearic acid-methanol solution were applied and evenly distributed. Thereafter, for all samples IR spectra in the range 3000 cm^-1 - 2700 cm^-1 in Transmission measured. subsequently were prepared so Samples with a UVA light source at 351 nm wavelength and a intensity of 3 mW cm^-2 each 60 min irradiation. While this UVA irradiation were examined at regular intervals of 15 min, for all Samples again IR spectra in the range 3000 cm^-1-2700 cm^-1 in Transmission measured. The predictable from these spectra residual value of stearic acid (in With respect to the value before UV irradiation) through the irradiation time was in the following chart, in accordance with <figref idrefs="S9">1</figref> for each Samples applied.