Modified zinc oxide-phosphate core-shell pigments in solvent-based paints

Purpose - The purpose of this paper is to present a new trend of anticorrosive pigments based on bulk (core) of zinc oxide covered with a surface layer of phosphates. Design/methodology/approach - A new batch of pigments based on core-shell theory containing a core (bulk) of cheap oxides covered by a layer of phosphates were prepared. These new pigments combined the properties of both components besides being more economically feasible. Simple chemical techniques were used to prepare these pigments. Characterization of these pigments using X-ray diffraction and scanning electron microscopy was carried out. Evaluation of these pigments using international standard testing methods was estimated. These pigments were incorporated in solvent-based paint formulations based on medium oil alkyd resin. The physico-mechanical properties of dry films and their corrosion properties using an accelerated laboratory test in 3.5 percent NaCl for 28 days were tested. Findings - It was found that those pigments based essentially on zinc oxide covered with a surface layer of phosphates were easily prepared, are economically feasible and can successfully replace original phosphates with similar efficiency in their corrosion protection behaviour. Practical implications - These pigments can be applied in other polymer composites, e.g. rubber and plastics, as a reinforcing agent. Originality/value - The prepared pigments are environmentally friendly and can replace other hazardous pigments (e.g. chromates) with almost the same quality in their performance; also they can be used in industries other than paints, e.g. paper, rubber and plastics composites.