WO2003106164A1

WO2003106164A1 - Substrate having a structured surface made of hydrophobic and hydrophilic areas

Info

Publication number: WO2003106164A1
Application number: PCT/EP2003/006350
Authority: WO
Inventors: Martin Mennig; Peter William Oliveira; Helmut Schmidt
Original assignee: Institut für Neue Materialien Gemeinnützige GmbH
Priority date: 2002-06-17
Filing date: 2003-06-16
Publication date: 2003-12-24
Also published as: EP1515841A1; DE10226971A1; AU2003238509A1

Abstract

Disclosed is a method for producing a substrate having a structured surface made of hydrophobic and hydrophilic areas, according to which the surface of a substrate that is provided with a hydrophilic layer topped by a hydrophobic layer is exposed so as to obtain an image, the hydrophilic layer being uncovered in the exposed areas as the superimposed hydrophobic layer decomposes during exposure. Particularly good results are obtained if the hydrophilic layer is photocatalytically active such that the hydrophobic layer decomposes in a photocatalytic manner. The substrates obtained by the inventive method are extremely suitable for printing microstructures onto a receiving medium.

Description

Substrate with a structured surface made of hydrophobic and hydrophilic areas

The present invention relates to substrates with a structured surface from hydrophilic and hydrophobic areas and their use in a planographic printing process.

The adjustment of the hydrophilicity or hydrophobicity of surfaces is technically important, since many applications are known in which it is necessary to make either a surface hydrophilic or hydrophobic as required, without major interventions being necessary. Depending on the state of crystallization, Ti0 ₂ surfaces can assume both hydrophilic and hydrophobic properties. Ti0 ₂ particles generally show hydrophilic properties when exposed to light and are suitable in surface layers to produce hydrophilic surfaces when exposed to light.

On the other hand, surfaces that are hydrophobized with silicone layers show a pronounced hydrophobic behavior and form contact angles of over 100 ° against water. Metal, glass or ceramic surfaces also become hydrophobic if they are coated with thin oil films.

Surface-structured systems from hydrophilic and hydrophobic areas can be used, for example, for printing processes in which a material is transferred imagewise to a receiving medium. It can be used, for example, to print images, record information or set up structures, for example for printed circuit boards. The manufacture of the surface structured systems is complicated and costly. As a rule, a multi-stage process is required, which includes complex chemical reaction chains and / or etching stages. This also means long production times and a high chemical requirement with the associated disposal problems. Especially with micro and nanostructures, these difficulties increase due to the required accuracy. In addition, the surface structures once produced can often no longer be changed, so that with one Damage or in the event of a desired change in the image to be printed, the entire substrate must be discarded.

The object of the invention was to provide a method, a surface structure can be made from hydrophobic and hydrophilic regions with the simple, cheap and quick way that is suitable for ^• printing of materials and the well structures in the micro and even in Nanometer range can be represented exactly. Reuse of the substrate should also be possible.

It has now surprisingly been found that hydrophobic coatings, when applied to hydrophilic layers, in particular to surfaces with photocatalytically active TiO _2l , quickly lose their hydrophobicity by exposure, preferably with UV light, and become hydrophilic at the exposed areas. Accordingly, the invention provides a method for producing a substrate with a structured surface from hydrophilic and hydrophobic regions, in which the surface of a substrate which has a hydrophilic layer and an overlying hydrophobic layer is exposed imagewise, the hydrophilic layer in the exposed regions is exposed by the decomposition of the overlying hydrophobic layer during exposure. Particularly good results have been achieved if the hydrophilic layer is photocatalytically active, so that there is a photocatalyzed decomposition of the hydrophobic layer. The substrates obtained in this way are outstandingly suitable for printing microstructures on a receiving medium.

A corresponding image or pattern of the hydrophobic and hydrophilic areas is formed on the surface by the imagewise exposure. Of course, the image-wise removal of the hydrophobic layer also results in structuring in the thickness direction of the layers. However, the two-dimensional pattern that forms on the surface is particularly relevant for the subsequent printing. However, the inclusion of the third dimension is also conceivable, for example in the case of holographic processes. The pattern that is formed can be any desired pattern. It can be a regular or irregular pattern. Regular shapes are, for example, points, lines or areas such as triangles, rectangles, polygons, circles or ellipses. Of course, it can also be curved lines or irregular surfaces. The desired overall pattern can be formed by combining individual shapes, for example to reproduce numbers, letters, images, circuits, other information or to build up certain structures. The pattern to be printed can correspond to the hydrophilic area or the hydrophobic area.

The hydrophilic layer and the hydrophobic layer are on a substrate. The substrate can have any convenient shape. It is e.g. as a plate or cylinder, which are suitable as a pressure plate or roller. The substrate can be any material suitable for the purpose. Examples of suitable materials are metals or metal alloys, glass, ceramics, including oxide ceramics, glass ceramics, paper or plastics, including rubber.

Of course, it can also be substrates that are provided with a surface layer, for which the materials mentioned above can also be used. The surface layer can e.g. be a metallization, an enamelling, a ceramic layer or a paint. With ceramic surfaces it can e.g. are thin coatings of ceramic components on metals. The substrates can be pretreated. For example, they can be cleaned, e.g. B. with commercially available alkaline cleaners, or be prepared for a coating, e.g. through corona treatment.

Examples of metals or metal alloys are steel, including stainless steel, chrome, copper, titanium, tin, zinc, brass and aluminum. Examples of glass are soda-lime glass, borosilicate glass, lead crystal and silica glass. It can be, for example, flat glass, hollow glass such as container glass, or laboratory equipment glass. The ceramic is, for example a ceramic based on the oxides Si0 _2, Al ₂ 0 _3l Zr0 ₂ or MgO or the corresponding mixed oxides. A lacquered surface can be formed from conventional base coats or lacquers based on organic binders. The substrate itself can optionally represent the hydrophilic layer, so that the hydrophobic layer is applied directly to a substrate with hydrophilic surface properties. However, the hydrophilic layer is preferably located on a separate substrate, in particular when using the hydrophilic, photocatalytically active layers.

There is a hydrophilic layer and a hydrophobic layer on the substrate. The concept of hydrophilicity / hydrophobicity as the basic concept of chemistry is well known to the person skilled in the art. Hydrophobic substances repel water, while hydrophilic substances attract water. The hydrophilic character can e.g. are formed by hydroxy, oxy, carboxylate, sulfate, suifonate functions or polyether chains in the substance. A hydrophobic character is e.g. typically generated by hydrocarbon residues such as alkyl residues or aromatic residues in the substance.

The hydrophobic or hydrophilic character of the layers is determined in particular by the substances used for the layers and, if appropriate, their modification. The person skilled in the art can readily see which materials and processing methods he has to select in order to arrive at hydrophilic or hydrophobic layers. The hydrophobic / hydrophilic character of a layer can e.g. be determined by the contact angle against water or another suitable solvent.

The difference between the hydrophilic character of one layer and the hydrophobic character of the other layer need only be so great that sufficient selectivity of the material to be printed is guaranteed for one of the two layers. The necessary settings are known to the person skilled in the art. The hydrophilic layer preferably has a contact angle against water measured on a smooth surface of <30 °, while the hydrophobic layer has a contact angle against water measured on a smooth surface> 85 °. The hydrophilic layers are in particular oxide layers. The hydrophilic character can be based in particular on hydroxyl groups on the surface of these layers. For example, it can be glass, ceramic or glass ceramic layers. Hydrophilic layers based on the oxides Si0 ₂ , Al ₂ O ₃ , Ti0 ₂ , Zr0 ₂ or MgO or the corresponding mixed oxides are preferred.

The hydrophilic layer comprises particularly preferably oxides or mixed oxides of glass or ^{'ceramic-forming} elements M, in particular at least one element M from main groups III to V and / or transition groups II to IV of the Periodic Table of the Elements and Mg. Preferably If it is the elements Si, Al, B, Sn, Ti, Zr, Mg, V or Zn, in particular those of Si, Al, Ti, Zr and Mg or mixtures of two or more of these elements. Of course, other glass or ceramic-forming elements M can also be installed, in particular those of elements of main groups I and II of the periodic table (eg Na, K and Ca) and of subgroups V to VIII of the periodic table (eg Mn _s Cr, Fe and Ni) , Lanthanides can also be used.

The inventors have found that it is particularly advantageous if the hydrophilic layer is photocatalytically active. This is achieved in that the layer contains or consists of photocatalytically active materials. The photocatalytic effect of many different materials has been known for a long time. Photocatalysts are able to catalyze certain reactions when exposed to light.

All photocatalytically active materials can be used as materials. Examples of materials that can act as photocatalysts are Ti0 ₂ , ZnO, SrTiO ₃ , BaTiO ₃ , K ₂ NbO ₃ , Fe ₂ O ₃ , Ta ₂ O _5. WO ₃ , Sn0 ₂ , Bi ₂ Ö ₃ , NiO, Cu ₂ O, SiC, MoS _2, InPb, RuO ₂ and CeO _2, wherein the metals Pt Pd, Rh, Ru, Nb, Cu, Sn, Ni and Fe can be used as additives (co-catalysts) or for doping ^"like. TiO ₂ or doped TiO ₂ are particularly preferred, for example Fe, Pd (as colloid) or Pt (in the form of platinum complexes) are suitable as doping for TiO _2. The use of TiO ₂ with cocatalysts can also be advantageous. It should be noted here that the photocatalytic activity of the materials generally also depends on the shape or the condition of the materials. For a layer to be photocatalytically active, it may be necessary, for example, for the materials, which may be photocatalytically active, to form a coherent surface, for example as a matrix surface or as more or less isolated particles, on the surface of the layer in order for an intended reaction to occur the interface can take place when exposed by photocatalysis. Therefore, ordinary glass or Ke ^{'ramikschichten,} even when they contain additions of elements that can be photocatalytically active, not photocatalytically usually active. The person skilled in the art knows what measures are required in order to obtain photocatalytically active layers.

The hydrophilic layer can be applied to the substrate in any way known to the person skilled in the art. For this purpose, a coating composition is applied to the substrate and hardened or compacted. The coating composition can be a powder of the materials for the layer, which is melted or sintered on the substrate by the powder coating process to form the layer by heat treatment. However, it is preferably a flowable coating composition, in particular in the form of a suspension or a sol.

The coating composition comprises the materials for the layer and a solvent. The materials for the layer can be contained as particles and / or as hydrolysates or precondensates. The materials are, in particular, the oxides of the above-mentioned elements or corresponding precursors. The coating composition preferably contains materials which are suitable for photocatalysis or their precursors. These materials for the layer are preferably used in the form of particles in the submicron, micrometer (below 1 mm) or in particular in the nanometer range, for example below 200 nm. When using photocatalytically active materials, the oxides are also preferred. Non-oxide photocatalysts can also be used, but care must be taken to ensure that a hydrophilic layer is obtained. The production of the particles from the materials for the hydrophilic layer can be carried out in a customary manner, for example by hydrothermal processes, flame pyrolysis, plasma processes, colloid techniques, sol-gel processes, controlled germination and growth processes, MOCVD processes and emulsion processes. The particles can also be produced in situ in the coating composition, for example using sol-gel processes. ^' These processes are described in detail in the literature.

The particles which can be used are usually also commercially available as powders or as suspensions or sol in a solvent. The particularly preferred Ti0 ₂ particles are available, for example, as P25 (d ₅₀ = 30-40 nm) from Degussa. SiO ₂ particles which can be used are, for example, silica sols, such as the Levasile®, silica sols from Bayer AG, or pyrogenic silicas, for example the Degussa Aerosil products.

The coating composition can also be obtained from hydrolyzable compounds by the sol-gel method. In the sol-gel process, which can also be used for the separate production of the particles, hydrolyzable compounds are usually hydrolyzed with water, optionally with acidic or basic catalysis, and optionally at least partially condensed. The hydrolysis and / or condensation reactions lead to the formation of compounds or condensates with hydroxyl, oxo groups and / or oxo bridges, which serve as precursors. Stoichiometric amounts of water, but also smaller or larger amounts can be used. The sol that forms can be adjusted by suitable parameters, e.g. Degree of condensation, solvent or pH, are adjusted to the viscosity desired for the coating composition. Further details of the sol-gel process are e.g. at C.J. Brinker, G.W. Scherer: "Sol-Gel Science - The Physics and Chemistry of Sol-Gel-Processing", Academic Press, Boston, San Diego, New York, Sydney (1990).

The hydrolyzable compounds that can be used have in particular the general formula MX _a , in which M is the glass or ceramic image defined above. Ending element is M, X is a hydrolyzable group or hydroxy, where two groups X can be replaced by an oxo group, and a corresponds to the valence of the element and is usually 3 or 4. Examples of the hydrolysable groups X, which may be the same or different, are hydrogen, halogen (F, Cl, Br or I, particularly Cl or Br), alkoxy (for example, Cι _-6 alkoxy, such as methoxy, ethoxy, n -Propoxy, i-propoxy and n-, i-, sec.- or tert-butoxy), aryloxy (preferably Cβ-io-aryloxy, such as phenoxy), alkaryloxy, e.g. benzoyloxy, acyloxy (e.g. C-ι- ₆ -AcyIoxy, preferably Cι_ ₄ -acyloxy, such as acetoxy or propionyloxy), amino and alkylcarbonyl (for example C _2-7 alkylcarbonyl such as acetyl). Two or three groups X can also be connected to one another, for example in the case of Si-polyol complexes with glycol, glycerol or pyrocatechol. The groups mentioned can optionally contain substituents, such as halogen or alkoxy. Preferred hydrolyzable radicals X are halogen, alkoxy groups and acyloxy groups.

The titanium compounds that can be used are in particular hydrolyzable compounds of the formula TiX ₄ . Specific and preferably used titanates for the production of a coating composition according to the sol-gel process are TiCl ₄ , Ti (OCH ₃ ) _4> Ti (OC ₂ H ₅ ) ₄ , Ti (2-ethylhexoxy) ₄ , Ti (n-OC ₃ H ₇ ) ₄ or Ti (i-OC ₃ H ₇ ) ₄ . Examples of hydrolyzable silanes which can be used to prepare the coating composition are Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (On- or -iC ₃ H ₇ ), Si (OC ₄ H ₉ ) ₄ , SiCI ₄ , HSiCI ₃ , Si (OOCCH ₃ ) ₄ . Further examples of hydrolyzable compounds of elements M which can be used are AI (OCH ₃ ) ₃ , AI (OC ₂ H ₅ ) _3j AI (0-nC ₃ H ₇ ) ₃ , AI (OiC ₃ H ₇ ) ₃ , AI (0-nC ₄ H9) _3l AI (O-sek.-C ₄ H ₉ ) ₃ , AICI ₃ , AICI (OH) ₂ , AI (OC ₂ H ₄ OC ₄ H ₉ ) ₃ , ZrCI ₄ , Zr (OC ₂ H ₅ ) ₄ , Zr (OnC ₃ H ₇ ) ₄ , Zr (OiC ₃ H ₇ ) ₄ , Zr (OC ₄ Hg) ₄ , ZrOCI ₂ , Zr (2-ethylhexoxy) ₄ , and Zr compounds which have complexing radicals, such as e.g. ß-diketone and (meth) acrylic residues, sodium methylate, potassium acetate, boric acid, BCI ₃ , B (OCH ₃ ) ₃ , B (OC ₂ H ₅ ) ₃ , SnCI ₄ , Sn (OCH ₃ ) ₄ , Sn ( OC ₂ H ₅ ) ₄ , VOCI ₃ and VO (OCH ₃ ) ₃ .

If appropriate, partially hydrolyzable compounds with non-hydrolyzable organic radicals can also be used, so that organically modified inorganic condensates are obtained. These can be used for flexibility or crosslink the hydrophilic layer. These are preferably silanes of the formula R _n SiX - _n , in which the radicals R are identical or different and represent non-hydrolyzable groups, the radicals X are identical or different and are as defined above for MX _a and n is 1 , 2 or 3. The non-hydrolyzable radicals R are, for example, alkyl (for example C ₄ alkyl), C _2-4 alkenyl, C ₂ . -Alkinyl, Cβ-io-aryl and corresponding aralkyl and alkaryl groups. The radicals R can have substituents. The substituents can be functional groups via which the condensate can also be crosslinked via the organic groups, or via which other polar groups are introduced. Typical substituents are, for example, halogen, epoxy (for example glycidyl or glycidyloxy), hydroxy, ether, amino, monoalkylamino, dialkylamino, optionally substituted anilino, amide, carboxy, alkenyl, alkynyl, acrylic, acryloxy, methacrylic, methacryloxy, mercapto, cyano, alkoxy, Isocyanato, aldehyde, alkylcarbonyl, acid anhydride and phosphoric acid. These substituents are bonded to the silicon atom via divalent bridging groups, in particular alkylene, alkenylene or arylene bridging groups, which can be interrupted by oxygen or -NH groups. Preferred examples of non-hydrolyzable radicals R with functional groups via which crosslinking is possible are glycidyloxypropyl and (meth) acryloxypropyl. ((Meth) acrylic stands for methacrylic or acrylic).

Suitable solvents are both water and organic solvents or mixtures. These are the usual solvents used in the field of coating. Examples of suitable organic solvents are alcohols, preferably lower aliphatic alcohols (Ci-Cs alcohols), such as methanol, ethanol, 1-propanol, i-propanol and 1-butanol, ketones, preferably lower dialkyl ketones, such as acetone and methyl isobutyl ketone, ethers, preferably lower dialkyl ethers, such as diethyl ether, or diol monoether, amides, such as dimethylformamide, tetrahydrofuran, dioxane, sulfoxides, sulfones or butylglycol and mixtures thereof. Alcohols are preferably used. High-boiling solvents can also be used. In the sol-gel process, the solvent can optionally be an alcohol formed from the alcoholate compounds during the hydrolysis. The coating composition can furthermore optionally contain polymers of all kinds as flexibilizers. If necessary, organic binders can be used. When particles are used in the coating composition, a hydrolyzate or condensate prepared by the sol-gel process can also serve as an inorganic binder, which is optionally organically modified. If functional groups are present in the organic modification, crosslinking is possible via this, as in the case of organic binders.

As said, it is preferred that the coating composition contains materials which are suitable for photocatalysis and which are preferably also present as particles or as a hydrolyzate precondensate. This preferred embodiment is explained in more detail below with reference to the particularly preferred, optionally doped titanium dioxide. The statements apply accordingly to other photocatalysts. Preferably more than 15% by weight, more preferably more than 30% by weight, in particular more than 60% by weight of the hydrophilic layer are photocatalytically active material. In particular, more than 80% by weight and preferably more than 95% by weight of the hydrophilic layer are photocatalytically active material.

The optionally doped titanium dioxide can be present in the coating composition in the form of particles or as a hydrolyzate precursor. In a preferred embodiment, the hydrophilic layer consists of the photocatalytically active material. The optionally doped titanium dioxide is preferably contained in the coating composition in the form of particles. The particles can optionally be mixed with organic and / or inorganic binders in the coating composition. All conventional binders are suitable as organic binders. The hydrolysates / condensates explained above are suitable as inorganic binders. For this, z. B. Suitable hydrolyzates / condensates on a silicate basis. In the embodiment in which the materials suitable for photocatalysis are used in the form of the hydrolyzates / precondensates, the hydrolyzable titanium compounds explained above come into consideration. In this case too in addition organic or inorganic binders, preferably based on silicate, can be used.

The usual coating methods can be used for coating the substrate with the coating composition, e.g. Diving, rolling, knife coating, flooding, pulling, spraying, spinning or painting. The applied coating composition is optionally dried and hardened or compacted.

If crosslinkable organic or inorganic binders are used, thermal or photochemical curing of the layer can be considered. Irradiation with UV light is expedient for photochemical curing. Without a crosslinkable group, the hydrophilic layer is compacted or burned in by heat treatment. The temperature and duration for hardening or compaction or baking naturally depend on the materials used. In general, temperatures between 90 and 600 ° C are appropriate for compression.

Post-treatments can be carried out to make the layer hydrophilic and / or photocatalytically active. After hardening / compacting, activation by exposure, preferably with UV light, is preferably carried out. However, visible light can also be used, provided the doping of the photoactive components is suitable for sensitivity in visible light. For example, It has been described that doping with platinum complexes is suitable for achieving high sensitivity even in visible light. Activation by exposure can cause the layer to become hydrophilic and / or the photocatalytic activity to develop if necessary. The activation is especially at. layers containing optionally doped titanium dioxide make sense.

The hydrophilic layer expediently has a thickness of 1 to 100 μm, preferably 2 to 20 μm and in particular 3 to 10 μm. In contrast is the the hydrophobic layer applied thereon is preferably extremely thin. In this sense it can also be called a film. The hydrophobic layer preferably has a layer thickness of not more than 100 nm, for example in the range from 50 to 100 nm. Even more preferably, the hydrophobic layer is a molecular film, ie one or a few “layers” of the hydrophobic layer forming substances on the surface of the hydrophilic layer, for example mono-, di- or trimolecular layers.

The hydrophobic layer is produced in particular by hydrophobizing the hydrophilic layer. For this purpose, a hydrophobizing agent is preferably applied in the usual way. All conventional hydrophobizing substances known in the art can be used for the hydrophobizing agent. This can e.g. Hydrocarbons, organic compounds with long alkyl chains or their salts, organic polymers, organically modified inorganic monomers or polymers, in particular silicon compounds, or mixtures thereof. The hydrophobizing substance can be used in pure form or preferably in a solvent. One or more hydrophobizing substances can be used.

Examples of hydrophobizing substances for the hydrophobic layer in the hydrophobizing agent are paraffins, waxes, fats and oils, fatty acids, oleic acids, metal soaps, organic tin compounds, silazanes, silanes and silicones. Examples of waxes are natural waxes, such as candelilla wax and camauba wax, synthetically modified waxes, such as montan ester waxes, or synthetic waxes, such as polyalkylene waxes. Silazanes have the formula H3Si- (NH-SiH ₂ ) n-NH-SiH ₃ , where n is greater than or equal to 1. They can be cyclic, oligomeric or polymeric compounds and they can, for example, be substituted with alkyl groups. Examples of usable silanes are silanes of the formula R _n SiX _4-n mentioned above. Compounds are preferred in which R is alkyl, aryl, alkaryl or aralkyl, in particular C ₄ -C ₄ -alkyl, such as methyl or ethyl, and X is halogen or alkoxy. Alkylchlorosilanes and alkylalkoxysilanes, for example methylchlorosilanes, such as dimethyldichlorosilane and trimethylchlorosilane, and methylethoxysilanes, such as dimethylethoxysilane, are preferred. Examples of silicones are alkyl silicone oils, e.g. Silicone oils with C- |. ₄ -alkyl or phenyl groups, for example methylphenyl silicone oils or methyl silicone oils, and polymethyl-H-siloxanes. Polydimethylsiloxanes (PDMS) are particularly suitable. Resin-like cross-linked siloxanes can also be used.

Water and / or organic solvents, such as e.g. Hydrocarbons, chlorinated hydrocarbons, ethers, esters, higher alcohols from butanol or the solvents mentioned above can be used. The hydrophobizing substance preferably forms a solution or an emulsion / dispersion in the solvent, e.g. aqueous emulsions. In addition to the hydrophobizing substance and the solvent, the hydrophobizing agent can also optionally contain metallic catalysts, emulsifying agents and / or polymers of all kinds as flexibilizers. The hydrophobizing agent is applied to the hydrophilic layer in a conventional manner. Any suitable application method can be used, e.g. Rubbing or the above coating processes. After that, there is usually only drying to evaporate the solvent. The layer thickness can e.g. controlled by dilution in the solvent. If necessary, heat treatment can also be carried out for stronger binding to the hydrophilic layer. As a rule, however, it is expedient that the hydrophobizing substances do not form a covalent bond with the surface groups of the hydrophilic layer, but such bonds do not result in any significant impairment.

The substrate thus obtained is exposed imagewise. The structuring can take place, for example, using a mask technique, holographic techniques, for example two-wave mixing, and laser writing processes. UV light or light in the visible range is preferably used for exposure. If laser light is used, commercially available systems (eg laser engraving devices) can be used. Laser light with radiation in the ultraviolet range but also in the infrared range (IR or UV range) is expediently used. A suitable laser is ^" the CO ₂ laser. UV lasers are preferably used in the case of photocatalytically active hydrophilic layers. The writing speed or the exposure time is adapted to the hydrophobic layer thickness and ranges from less than 1 s to longer exposure times. The exposure of the surface causes the hydrophobic layer to decompose in the image-wise exposed areas, the hydrophilic layer underneath being exposed in these areas. In this way, the desired structure is formed on the surface. The structure is preferably a microstructure, ie at least in some areas, structures with subtleties in the micrometer range are formed. Without wishing to be bound by theory, it is assumed that when the hydrophobic layer is decomposed, the hydrophobizing substances therein are decomposed, evaporated or oxidized. Residue-free decomposition preferably takes place. The decomposition is most effective if it is supported by photocatalysts in the hydrophilic layer, so that photocatalytic decomposition is preferred.

The substrates obtained in this way are outstandingly suitable for printing a structure on a receiving medium. Here, a printing material that is hydrophobic or hydrophilic is applied to the substrate, the material being deposited due to the hydrophilic / hydrophobic character only on the hydrophilic / hydrophobic areas of the structured surface of the substrate. Of course, a hydrophilic material is distributed over the hydrophilic areas of the surface and a hydrophobic material over the hydrophobic areas. The substrate loaded with the material is then brought into contact with a receiving medium, expediently using pressure, and then the substrate and the receiving medium are separated from one another with image-wise transfer of the material to the receiving medium.

Apart from the substrate according to the invention, the printing process can be carried out as in a conventional planographic printing process. Examples of planographic printing processes are lithography and offset printing. The substrate can be used, for example, as a printing plate or roller. The printing material can be applied, for example, by spraying, dipping, knife coating, brushing or by means of rollers. With the method according to the invention, it is possible to obtain a transfer of almost any liquid to pasty components by alternating hydrophilicity and hydrophobicity. The printing material has a liquid to pasty consistency. For example, they can be aqueous solutions, suspensions or pastes. The usual materials known in the art for printing or transmission can be used. It can be, for example, metal-containing pastes, ceramic-containing pastes and semiconductor-containing pastes or corresponding suspensions. If the loaded surfaces are pressed onto a receiving medium, this interacts with the components located on the loaded surface, so that an image of the structure can be produced on the corresponding receiving medium. The material transferred to the receiving medium can be dried, hardened, compressed or further processed in another way.

The receiving medium can e.g. B. be one that is suitable for building microelectronic circuits. For example, around plastic, e.g. a plastic film, metal, paper, glass or a ceramic surface. Of course, the properties of the receiving medium, e.g. regarding the hydrophilicity with which the material for printing is to be coordinated.

When using photocatalytically active, hydrophilic layers, the exposed areas can also be covered with another hydrophilic layer as a protective layer to avoid undesired reactions. The actual material for printing can then be immobilized or deposited on this second hydrophilic layer.

Another advantage of the invention is that already structured substrates can also be restructured. This can be useful, for example, after damage or a desired change to the pattern to be printed. Thus, after a rough cleaning of the system (to remove residual printing material), the structured substrate, which was used for one or more printing processes, can be exposed areally, so that it is freed of the hydrophobic layer. After that, the entire surface can be waterproofed again. The substrate regenerated in this way is then available for restructuring with a different image pattern. In this way, any re-use that can be repeated is possible. The application of the invention ranges from printing processes in the printing industry to a transfer technique in which certain information or structures of the materials grown on the substrate are transferred. Another application is the construction of structures, in particular microstructures, such as microreactors, spot plates or also reactors for combinatorics, in which corresponding hydrophilic or hydrophobic areas are formed. Another application is the production of very fine structures in the nano or micrometer range, in which the hydrophilicity or the hydrophobicity is used to accommodate cells or other biological components in desired arrangements (arrays).

Claims

claims

1. A method for producing a substrate with a structured surface from hydrophilic and hydrophobic areas, in which the surface of a substrate having a hydrophilic layer and an overlying hydrophobic layer is exposed imagewise, the hydrophilic layer in the exposed areas by the the exposure to decomposition of the overlying hydrophobic layer is exposed.

2. A method for producing a structured surface substrate according to claim 1, wherein the hydrophilic layer is a hydrophilic, photocatalytically active layer, the hydrophilic layer being exposed in the exposed areas by photocatalytic decomposition of the overlying hydrophobic layer.

3. A method for producing a substrate with a structured surface according to claim 1 or 2, characterized in that exposure is carried out with laser light.

4. A method for producing a substrate with a structured surface according to one of claims 1 to 3, characterized in that exposure to UV light, IR light or light in the visible range.

5. A method for producing a substrate with a structured surface according to one of claims 1 to 4, characterized in that a mask method, a holographic method or a laser writing method is used for the imagewise exposure.

6. A method for producing a substrate with a structured surface according to one of claims 1 to 5, characterized in that a coating composition for the hydrophilic layer, which preferably comprises materials suitable for photocatalysis or their precursors, is applied to the substrate and cured or compacted and the hardened or densified layer by applying a hydrophobizing agent.

7. A method for producing a substrate with a structured surface according to any one of claims 2 to 6, characterized in that the hardened or compacted layer is activated before exposure to the hydrophobic layer by exposure to form a hydrophilic, photocatalytically active layer.

8. A method for producing a substrate with a structured surface according to one of claims 2 to 7, characterized in that the exposed hydrophilic, photocatalytically active layer is covered with another hydrophilic layer as a protective layer.

9. A process for printing a material with a liquid to pasty consistency, in which a) the material, which is hydrophilic or hydrophobic, is applied to a substrate with a structured surface produced by the process of one of claims 1 to 8, it being in accordance with its hydrophilic or hydrophobic nature distributed over the hydrophilic areas or onto the hydrophobic areas, b) brings the substrate loaded with the material into contact with a receiving medium and transfers the material to the receiving medium in an imagewise manner.

10. A method for printing a material according to claim 9, characterized in that a microstructure is built up on the receiving medium.

11. A method for printing a material according to claim 10 or claim 11, characterized in that after printing one or more times with the substrate, if necessary, the surface is at least roughly freed of residual printing material, the structured surface is exposed in terms of area to the hydrophobic layer by decomposition to remove, and hydrophobicizing the hydrophilic layer again with a hydrophobizing agent, so that the substrate can be used for structuring with a different image pattern.

12. Substrate comprising a hydrophilic, photocatalytically active layer and an overlying hydrophobic layer.

13. The substrate according to claim 12, characterized in that the hydrophobic layer is arranged imagewise on the hydrophilic layer, so that a structured surface results from hydrophobic areas and hydrophilic areas.

14. Substrate according to claim 12 or claim 13, characterized in that the hydrophilic, photocatalytic active layer comprises TiO ₂ or doped TiO ₂ or consists of TiO ₂ or doped TiO ₂ .

15. Substrate according to one of claims 12 to 14, characterized in that the hydrophobic layer comprises or consists of paraffin, wax, oil, oleic acid, fat, an organotin compound, a metal soap, fatty acid, silane, silicone and / or silazane.