Coating comprises a particle layer made from a nano-particulate photocatalytically active material arranged on a primer layer made from porous inorganic or inorganic-organic material

The invention relates to a coating.

In the field of coatings, it is known primer layers, usually made of Silicon dioxide, applied on which then layers or layers of photocatalytic active oxides are deposited. The deposition is usually by Vacuum method, in individual cases by titanium dioxide / silica sol-gel mixtures.

From WO 97/23572 is a process for hydrophilizing the surface of a substrate known by photocatalysis. A substrate is covered with a photocatalytic TiO₂-Layer covered, the surface of a solid acid to increase the proportion of Hydrogen bonds at the solid-liquid interface. At the photoexcitation the proportion of hydrogen bonds is increased and thus the adsorption of Water molecules from the atmosphere at terminal TiOH groups and bridge OH Accelerated groups. This forms a dense physically adsorbed water film, which promotes the hydrophilicity.

WO 98/03607 describes a composition for the hydrophilization of surfaces and generation of antifogging properties consisting of photocatalytic particles Metal oxide, at least one component from the group of particulate SiO₂, Precursors, the SiO₂Films can form as well as solvents exist after application and drying or heating forms transparent films.

From WO 99/41322 is a coating material for the formation of a photocatalytic known hydrophilic film, which consists of an amorphous TiO₂Precursor, crystalline TiO₂ and a precursor for the formation of siloxane bonds exists.

WO 99/64364 discloses a process for producing a fibrous substrate whose surface is at least partially coated with a photocatalytic and hydrophilic coating, wherein photocatalytic semiconductor material is based on oxide and sulfur-based, especially TiO₂which crystallizes at least partially in anatase form, connected by means of adhesion promoter with the fiber material and the TiO₂ as particles in colloidal suspension or in powder form.

From EP 1 118 385 A1 is a process for the preparation of a photocatalytically active Material by coating a substrate with a photocatalytically active metal oxide and / or its precursor and rapid heating of the substrate to 100 to 600 ° C. known.

EP 1 074 525 A1 relates to an article with photocatalytic activity consisting of a substrate on which a primer layer of an n-type semiconductor is arranged, which again has a photocatalytic layer of an n-type semiconductor.

In WO 01/21722 is a photocatalytic, hydrophilic coating material described, which is easily applied to surfaces and a high degree of permanent Has hydrophilicity and transparency. It contains water, a photocatalytically active Metal oxide, an alkyl silicate and an alkali silicate.

The object of the invention is a new coating with photocatalytic properties to create both the largest possible photocatalytic activity as well as an optimal moisture exchange is guaranteed.

In the context of the invention, this object is achieved in that on a primer layer porous inorganic or inorganic-organic material from a particle layer at least one nanoparticulate photocatalytically active substance is applied, wherein in this particle layer, individual particles having an average particle size of 2 to 150 nm are arranged at a distance between 1 and 50 nm from each other on the primer layer.

The invention is based on the finding that the level of photocatalytic activity has different influence parameters. Main factor is the surface and thus the Exchange area of ​​active sites. Disruptions of activity are in particular due to the Coverage of the photocatalytically active centers, eg. As caused by silanization.

Furthermore, in addition to the UV irradiation, a continuous moisture film and Oxygen is indispensable for the macroscopic effects of photocatalytic activity.

It has surprisingly been found in the context of the invention that by the Structure of the coating according to the invention a much larger active surface is produced as in known coatings, which is due to the fact that a Nanoparticles of about 15 nm diameter a surface between 400 and 800 nm² having. The hydrophilic primer layer acts as a reservoir for its porosity Water and dissolved oxygen and still has a barrier effect to the substrate so that the coating of organic based substrates, such as Plastics, natural materials, leather, textiles or paper is possible. Due to the fact, that the particle layer is not dense, there are diffusion paths on the surface. A preferred embodiment of the invention is that the primer layer Silica, zirconia, alumina, mixed oxides thereof or organic modified compounds thereof.

In particular, therefore, primer layers come from the pure oxides (in particular Silica), mixed oxides thereof or organically modified compounds based on the pure oxides or the mixed oxides (for example, silicon-organic Compounds, such as methyltriethoxysilane) in question.

It has proved to be advantageous that the primer layer has a porosity of less than 2 nm having.

An embodiment of the invention is that the primer layer has a layer thickness of 50 nm to 1 .mu.m, preferably from 100 to 900 nm.

It is advantageous that the particle layer of ZnO, CaTiO₃, SnO₂, MoO₃, Fe₂O₃, WHERE₃, Nb₂O₅. SiC, Ti_xZr_1-xO₂, ZrO, TiO₂, in particular the anatase modification of TiO₂, or selenium salts or mixtures thereof.

An embodiment of the invention is that the mean particle size of the particles in the particle layer is 5 to 50 nm, preferably 5 to 20 nm.

According to the invention it is provided that the particles of the particle layer with the primer layer are linked by a partial silanization.

In the context of the invention is also a method for applying a novel invention Coating on a substrate, wherein a coating according to the invention on a Substrate applied and then cured.

It is expedient that the primer layer produced by the sol-gel process becomes.

Furthermore, it is according to the invention that the primer layer and the particle layer in each case by Spraying, pouring, flooding, dipping, rolling or spinning applied to the substrate become.

An embodiment of the method is that the particle layer on the not yet hardened primer layer is applied.

In another embodiment of the method is provided that the particle layer on the pre-dried primer layer is applied.

Furthermore, it is expedient that the predrying of the primer layer thermally at Temperatures between room temperature and 1200 ° C and / or carried out by jet drying.

A development of the invention is that the curing of the coating thermally at temperatures between room temperature and 800 ° C and / or by Beam drying takes place.

By jet drying is meant drying by electron beam, UV radiation, Microwaves, etc.

Finally, a use of the coating according to the invention as a coating for Plastics, textiles, ceramics, leather, wood, metals or paints within the scope of the invention. The structure of a coating according to the invention is described below with reference to a Drawing of an embodiment illustrated and described, as well as examples specified.

It shows

<b>FIG.</b> 1 is a schematic representation of a coating according to the invention.

On the substrate, which are surfaces of plastics, textiles, ceramics, Leather, wood, metals or lacquer-coated surfaces can act first a primer layer <b>1</b> made of silicon dioxide applied in the sol-gel process.

This primer layer <b>1</b> has no photocatalytic activity and serves to delimit from the substrate as well as due to the hydrophilic properties of the siloxane network as Water-tank. The porosity of the primer layer<b>1</b> lies in the range &lt;2 nm, the layer thickness between 50 nm and 1 μm, with layer thicknesses between 100 and 900 nm being preferred become.

On this primer layer <b>1</b> becomes a particle layer <b>2</b> applied, which is not a closed layer, but by individual, spaced apart (distance about 1 to 100 nm) particles having an average particle size of 2 to 150 nm, wherein a Particle size of 5 to 50 nm is preferred and from 5 to 20 nm is particularly preferred. The Particles are made of titanium dioxide, with the anatase modification due to their high photocatalytic activity is preferred. Due to the spacing of the particles and its nanostructure becomes a maximum active surface of the photocatalytically active Particles reached. Water can diffuse through this layer to the surface, so that a Protection against deactivation of the water reservoir by the photoactivity of the water reservoir Nanoparticles is achieved.

The coating can be applied to a variety of substrates, such as Textiles, leather, paper, concrete, stone, plaster or painted surfaces. It is suitable for Objects of all kinds, eg. As shoes, garments, tarpaulins, posters, components (eg. Sunblinds, window profiles (in particular of PVC), conservatories, glass domes, Façade elements, roof tiles, shutters, fireplaces, door and window handles), telephone booths, Monuments, satellite systems, antennas, bridges, buildings (especially skyscrapers), Flower pots, garden furniture, garden tools, garden gnomes, bus stops, electricity pylons, Electricity boxes, gutters, playground equipment, tombstones, billboards, posters, kitchens and kitchen appliances, vehicles and vehicle parts (eg vehicle mirrors, vehicle paints, Vehicle rims, vehicle windows, bumpers, truck tarpaulins, vehicle registration plates), Road signs, traffic mirrors, bicycles, motorcycles, spacecraft, and planes Aircraft parts, helicopters, satellites, spacesuits, medical devices, medical Rooms and sanitary facilities, swimming pools, tents, solar panels and cells, electrical and electronic components (eg wires, cables, lamps, lanterns, Measuring devices), optical lenses or machine parts.

Embodiment 1

primer solution

To 208.3 g [1 mol] of tetraethoxysilane (TEOS) is added 100 g of 0.1 molar HNO₃ added and 12 h touched. The hydrolyzate is treated with 892 g of isopropanol to a solids content of 5% diluted.

particle solution

2 g of titanium dioxide in the modification anatase (nanopowder, particle size 10 nm) are in 98 g Disperse acetylacetone and stirred for 30 min. It entsteht a translucent dispersion a solids content of 2% TiO₂,

A substrate using the example of an aluminum plate of 100 × 100 × 3 mm is used with the Sprinkle primer solution and dried for 24 h at room temperature. After that, the Particle dispersion with a wet film thickness of 5 microns misted by spray coating and 2 hours ventilated. During this time, the particles are partially silanized at the contact points, resulting in the very good adhesion. The photocatalytic surface coverage is then compressed for 2 h in a convection oven at 300 ° C. It creates a visually opposite the substrate material imperceptible photocatalytic surface occupation with partially silanized highly active nanoparticles.

To activate the photocatalytic activity of the anatase becomes the substrate <b>5</b> Days in the Outside (sunshine) stored.

The photocatalytic surface coverage has an extremely high abrasion resistance Steel wool (50 strokes - no effect loss), high chemical resistance (2 h 1% KOH - no attack) and very good adhesion (crosshatch, tape test - very good) result.

After external storage, the photocatalytic coverage shows a contact angle of 10 ° against water and anti-fog properties when breathed. After<b>3</b>Weekly storage of the photocatalytically occupied substrate together with an uncoated substrate a busy street can be clearly seen a significantly reduced Pollution tendency of the photocatalytically occupied surface.

Embodiment 2

primer solution

To 208.3 g [1 mol] of tetraethoxysilane (TEOS) is added 100 g of 0.1 molar HNO₃ added and 12 h touched. The hydrolyzate is mixed with 22.2 DAMO (Degussa) and quickly added 1227 g Water diluted to a solids content of 5%.

particle solution

2 g of titanium dioxide in the modification anatase (nanopowder, particle size 10 nm) are in 98 g Disperse acetylacetone and stirred for 30 min. It entsteht a translucent dispersion a solids content of 2% TiO₂,

A substrate using the example of a float glass plate of 100 × 100 × 3 mm is used with the Sprinkle primer solution and dried for 24 h at room temperature. After that, the Particle dispersion with a wet film thickness of 5 microns misted by spray coating and 2 hours ventilated. The photocatalytic surface coverage is then for 2 h im Convection oven compressed at 300 ° C. It creates a transparent, visually opposite the Substrate material imperceptible photocatalytic surface occupation with partially silanized highly active nanoparticles.

To activate the photocatalytic activity of the anatase becomes the substrate <b>5</b> Days in the Outside (sunshine) stored.

The photocatalytic surface coverage has an extremely high abrasion resistance Steel wool (50 strokes - no effect loss), high chemical resistance (2 h 1% KOH - no attack) and very good adhesion (crosshatch, tape test - very good) result.

After external storage, the photocatalytic coverage shows a contact angle of 10 ° against water and anti-fog properties when breathed. After<b>3</b>Weekly storage of the photocatalytically occupied substrate together with an uncoated substrate a busy street can be clearly seen a significantly reduced Pollution tendency of the photocatalytically occupied surface.

Embodiment 3

primer solution

To 208.3 g [1 mol] of tetraethoxysilane (TEOS) is added 100 g of 0.1 molar HNO₃ added and 12 h touched. The hydrolyzate is mixed with 27.8 g of GLYMO (Degussa) and 1.79 g of DAMO (Fa. Degussa) and diluted with 1200 g of ethanol to a solids content of 5%.

particle solution

2 g of titanium dioxide in the modification anatase (nanopowder, particle size 10 nm) are in 98 g Disperse acetylacetone and stirred for 30 min. It entsteht a translucent dispersion a solids content of 2% TiO₂,

A substrate using the example of a corona-treated plastic plate of 100 × 100 × 3 mm (Polycarbonate MAKROLON, Bayer) is sprayed with the primer solution and 1 h at 80 ° C dried. Thereafter, the particle dispersion with a wet film thickness of 5 microns misted by spray coating and flashed for 1 h. The photocatalytic Surface coverage is then compressed for 2 h in a convection oven at 130 ° C. It arises a photocatalytic optically imperceptible to the substrate material Surface coverage of partially silanized highly active nanoparticles.

To activate the photocatalytic activity of the anatase becomes the substrate <b>5</b> Days in the Outside (sunshine) stored.

The photocatalytic surface coverage has an extremely high abrasion resistance Steel wool (50 strokes - no effect loss), high chemical resistance (2 h 1% KOH - no attack) and very good adhesion (crosshatch, tape test - very good) result.

After external storage, the photocatalytic coverage shows a contact angle of 10 ° against water and anti-fog properties when breathed. After<b>3</b>Weekly storage of the photocatalytically occupied substrate together with an uncoated substrate a busy street can be clearly seen a significantly reduced Pollution tendency of the photocatalytically occupied surface.

Embodiment 4

primer solution

To 208.3 g [1 mol] of tetraethoxysilane (TEOS) is added 100 g of 0.1 molar HNO₃ added and 12 h touched. The hydrolyzate is mixed with 30 g of silica sol 200S / 30, 27.8 g of GLYMO (Degussa). and 22.2% DAMO (Degussa) and with 1418 g of water / ethanol mixture (3: 1) diluted to a solids content of 5%.

particle solution

2 g of titanium dioxide in the modification anatase (nanopowder, particle size 10 nm) are in 98 g Disperse acetylacetone and stirred for 30 min. It entsteht a translucent dispersion a solids content of 2% TiO₂,

A substrate using the example of a corona-treated plastic plate of 100 × 100 × 3 mm (Polycarbonate MAKROLON, Bayer) is sprayed with the primer solution and 1 h at 80 ° C dried. Thereafter, the particle dispersion with a wet film thickness of 5 microns misted by spray coating and flashed for 1 h. The photocatalytic Surface coverage is then compressed for 2 h in a convection oven at 130 ° C. It arises a photocatalytic optically imperceptible to the substrate material Surface coverage of partially silanized highly active nanoparticles.

To activate the photocatalytic activity of the anatase becomes the substrate <b>5</b> Days in the Outside (sunshine) stored.

The photocatalytic surface coverage has a high abrasion resistance against steel wool (50 strokes - no effect loss), high chemical resistance (2 h 1% KOH - no attack) and very good adhesion (crosshatch, tape test - very good) result.

After external storage, the photocatalytic coverage shows a contact angle of 10 ° against water and anti-fog properties when breathed. After<b>3</b>Weekly storage of the photocatalytically occupied substrate together with an uncoated substrate a busy street can be clearly seen a significantly reduced Pollution tendency of the photocatalytically occupied surface.