Small size, big impact09/11/2009 A world first has been rolled out by the Bühler affiliate PARTEC: OxylinkTM improves the chemical resistance and barrier strength of water-based coatings while at the same time reducing the drying time. This ultimately also reduces the processing times – whether the product formula has been designed for wood or furniture, for metals or plastics, for industrial maintenance or for machinery. This highly effective and broadly applicable additive technology is based on ZnO nanoparticle dispersions. Environmentally friendly and cost-saving water-based coating technology is a modern trend. But the possible applications of water-based coatings appear to be limited because many of their properties are often unable to reach the same quality level as solvent-based alternatives. Chemicals in the household or in industrial applications destroy the protective layer. During cleaning or polishing, the surface may be damaged and moisture will enter the substrate.
Protection from the inside
The OxylinkTM additive for water-based coatings developed by the specialists of the Bühler affiliate PARTEC acts from within the coating, improves curing of the polymer, and is virtually solvent-free. Based on ZnO nanoparticles, it imparts significantly better application characteristics to waterbased coatings and can even be used in clear high-performance and high-gloss coatings. Of course, OxylinkTM is also water-based so that no additional emissions or obnoxious odors are created.
Nanoparticles impart new features
Additives based on nanoparticles are distinguished more by their unique property profile than by any single characteristic. Nanoparticles possess the inherent properties of the material from which they are made, for example hardness, refraction index, UV absorption, or catalytic activity. These functionalities can be incorporated in products such as coatings and thus produce a sustainable improvement of the product characteristics. This is especially beneficial in combination with the most typical feature of nanoparticles: Sufficiently small particle will produce trans- parent materials, since light scattering decreases with the particle size.
The two sides of nanoparticle properties
Of special interest are those properties of nanoparticles which depend solely on their size. The two sides of nanoparticles properties depend greatly on these “dimensional characteristics”: Powders consisting of small particles have an incredibly high specific surface area. In product formulas, the surface of the interface between the particles and the formula is transformed. More interfaces generate more interactions between the matrix and the particles and thus influence the material. These interactions in turn influence functionalities such as toughness and strength as well as viscosity, transparency, and homogeneity of the product. Therefore, targeted control of the interface between the particles and the medium on the basis of sophisticated process parameters is crucial for successful product development. OxylinkTM enables the beneficial interactions of inorganic metal oxides on water-based coatings, and unique chemico-mechanical processing by Bühler ensures easy application.