Ink printability is a function of the physical and chemical properties of the functional element, the binder, the solvent and the additives in the ink formulation. Rheological properties and surface energy are used to determine an ink’s printability for a selected printing process. Viscosity, a commonly reported property of rheology, is the deformation resistance of an ink for given environmental conditions (e.g. shearing force and shearing speed, interaction of surface and surface geometry, and temperature), and thus, each printing technology requires a different ink rheology. Surface tension, a measurement of surface energy, defines the interaction between the ink and a substrate. It is critical parameter and is a measure of ink wetting to a selected substrate, resulting in its final deposition geometry.
Printing ink rheology is important for both traditional highly viscous, high solids content inks as well as for the newer type of functional inks. The latter have usually a lower viscosity and a lower solids content compared to traditional inks suitable for inkjet printers and printed electronics.