Koenig & Bauer AG (Wurzburg, DE) abhesive layer and to a method for producing an abhesive coating from cross-linked inorganic nanosols. An abhesive object or substance is slippery such as Teflon and is the opposite of adhesive. The abhesive layer has a strongly repelling effect with respect to adhesive materials, a good scratch resistance as a result of the inorganic network and good resistance to organic solvents. The non-stick nanoparticle coatings garnered U.S. Patent 7,651,560.
Inventors Gunter Risse and Michael Koch developed an abhesive layer, which not only has a strong abhesive effect especially with respect to adhesive liquids or pastes, such as printing inks and, while adhering well to the coated materials, but also has an improved, wear resistance. This objective is accomplished by an abhesive layer or abhesive coating of cross-linked inorganic nanosols with additions of polyorganosiloxanes, which form a three-dimensional network in the layer.
The inventive abhesive layer or abhesive coating is produced from inorganic nanosols by means of the sol-gel method. To begin with, inorganic particles in the nanometer range (nano particles) are obtained from an alkoxysilane by hydrolysis and partial condensation with the addition of additives. A nanosol is produced by colloidally dispersing the inorganic nanoparticles in an alcohol. The nanosol is modified by the addition of polyorganosiloxanes with multiple bonds and of further additives, which promote cross-linking.
In order to increase the wear resistance, the nanosol may be modified additionally with particles of a hard material, after which it is applied on the surface of a carrier material. During a subsequent heat treatment, the solvent is removed and the layer gels and shrinks. At the same time, the inorganic nanoparticles are cross-linked and, parallel to this, the polyorganosiloxanes also form a network, in that, to begin with, chains are formed in the gel and are connected during the further shrinkage of the gel into spatial networks. Organic solvents, alkanols such as butanol are preferred dispersants for the nanosol.
The inventive abhesive layers or coatings have a strongly abhesive effect with respect to water and water-based detergents, highly viscous liquids and pastes, such as printing inks or lacquers, as well as with respect to adhesive tapes. Because of very good adhesion and high wear resistance, they are also very suitable for uses, in which they are subjected to mechanical stresses, such as in printing presses for guiding printing stock.
The inventive abhesive coating or layer is also suitable for greatly reducing the adhesion of layers of water or ice on surfaces exposed to the elements, so that these deposits can be removed very easily. The abhesive coating can be used, for example, for keeping glass panes of vehicles, aircraft or ships free of water drops, deposits or ice and for greatly reducing the expense of removing ice and contamination from surfaces. Likewise, the adhesion of water or sewage to sanitary facilities of fittings is reduced so that lime deposits, for example, can at least be reduced.
For coating surfaces, which are to be protected, the nanosol is applied on the surface to be protected by brushing or spraying and, depending on the thickness of layer that is to be achieved, may be subjected to an intermediate drying. To achieve transparency of the abhesive coating, the layer is polished. As a result of the cross-linking reactions taking place with the evaporation of the solvent, the coating develops pronounced abhesive properties already without any additional heat treatment.
The inventive abhesive coating or layer is also suitable for greatly reducing the adhesion of layers of water or ice on surfaces exposed to the elements, so that these deposits can be removed very easily. The abhesive coating can be used, for example, for keeping glass panes of vehicles, aircraft or ships free of water drops, deposits or ice and for greatly reducing the expense of removing ice and contamination from surfaces. Likewise, the adhesion of water or sewage to sanitary facilities of fittings is reduced so that lime deposits, for example, can at least be reduced.
For coating surfaces, which are to be protected, the nanosol is applied on the surface to be protected by brushing or spraying and, depending on the thickness of layer that is to be achieved, may be subjected to an intermediate drying. To achieve transparency of the abhesive coating, the layer is polished. As a result of the cross-linking reactions taking place with the evaporation of the solvent, the coating develops pronounced abhesive properties already without any additional heat treatment.
