High shear viscosity measurement to predict processability

 
Understanding rheological behavior of inks is a guarantee of high-quality results and limiting process issues like bleeding and clogging the printing head. FluidicamRHEO is a new microfluidic rheometer used for products from water like to thick formulations, allowing viscosity measurements as a function of shear rate (up to 105 s-1) and temperature. A sample and a viscosity standard are pushed through a microfluidic chip (Y-junction) at controlled flow rates. Images of the resulting laminar co-flow are acquired and the position of the interface is measured. The position is related to the viscosity and the flow rate ratio allows viscosity determination of the sample. Ceramic inks and also sprayable coating solutions were measured at high shear rates at temperature and shear rate process conditions of the printing head and roller coating. FluidicamRHEO discriminated the viscosity with 0.5 cP precision and in some cases brought out shear thinning behavior occurring only at high shear rates.