‘Thixing’ Rheology with AEROSIL® Fumed Silica
Peter Lederhos, Coatings Technical Market Manager, BL Silica, Evonik Industries
The rheological properties of paints and coatings can be regulated according to the needs with either hydrophilic or hydrophobic AEROSIL® fumed silica. Added amounts of 0.3 – 1.0 %, based on the total formulation, are typical in nearly all solvent and water-based systems, as well as in high-solids coatings. The incorporation of fumed silica particles into a coating generally produces a pseudoplasticity that is often linked to a thixotropic effect, i.e. a dependence on time. The dependence of the flow behaviour of pseudoplastic coating systems on the shear rate guarantees high level application due to the low viscosity at high shear rates.
The high viscosity of a coating at low shear forces or at rest ensures an increased maximum wet-film thickness by using AEROSIL® fumed silica. It also serves to counteract the sedimentation of pigments and fillers.
Presenter’s Personal Profile
Peter Lederhos is Technical Market Manager for Evonik Industries AG’s Silica Business Line.
He is a graduate coating technician and has been responsible for the technical aspects of using silica products in different coating applications for eight years. Besides conventional coating he is also responsible for silica use in Printing Inks applications.
Peter is part of a team that covers the EMEA and South America regions.