Impact of ink evaporation on drop volume and velocity

A model has been developed to predict the impact on drop volume and velocity of selective evaporation of certain components of a multi-component ink from ink jet channels to ambient. The analysis consists of three steps: 1) changes in ink concentration along channels due to evaporation, 2) resulting spatial and temporal changes in ink viscosity leading to viscous plugs near nozzles, and 3) impact of this viscosity distribution on drop ejection process, i.e., drop volume and velocity. In the first step, an evaporation model which uses a number of analytical and numerical tools is developed to quantify the effects of channel geometry, material properties and ambient conditions. The second step essentially comes from measurements or data found in the literature. Finally the results from the first two steps are integrated into a numerical drop ejection model to determine the impact of evaporation on the hydrodynamic behavior of the system. The model has been found to agree very successfully with available experimental data covering a range of waiting (evaporation) time from 0 to 40 seconds.