Morphology-control on the nanoscaie: recent developments in the encapsulation of metallic effect pigments

摘要

Today,corrosion protection of metallic effect pigments(aluminium or brass)through encapsulation with silica(SiO2)is state of the art.Especially premium products for powder coatings or water-based industrial and automotive applications are broadly available.Although SiO2-treated pigments offer outstanding properties regarding stability,optics,hiding power and ease of use,this is not enough for tomorrow's markets with increasing and more diverse requirements.In our work,we show how the versatility of the underlying Sol-Gel chemistry allows meeting these requirements.After introducing the general silane-based encapsulation,we focus on new concepts and present some selected applications.Using the classical Sol-Gel process as starting point,one aspect of the current research is to increase the compatibility of the silica phase to other organic or inorganic phases.This multi-phase approach effectively leads to improved and new properties,like e.g.corrosion protection,colour,or electrical conductivity.It is crucial for the application performance to control the morphology of the nano-sized domains;unwanted side effects include agglomeration,and loss of orientation of the metallic pigments.