Transport and drying of aqueous co-solvent solutions in cellulose-based porous media at elevated temperatures

Inspired by inkjet printing technology, we systematically investigated the transport and drying of model inks — aqueous solutions of so-called co-solvents such as glycerol and ethylene glycol oligomers — in paper at elevated temperatures. We monitored the drying process in-situ using optical transmission imaging and infrared thermography, complemented by gravimetric mass-loss measurements. The results reveal two distinct stages, which are primarily associated with water evaporation and with pore–fiber transport or evaporative loss of the co-solvent, respectively. Steady-state models for heat- and mass transfer accurately reproduce the drying time and the amplitude of evaporative cooling. Spatially-resolved optical transmission measurements show non-uniform co-solvent distributions in the inter-fiber pores, especially for high molecular weights. Our findings provide quantitative insight into the drying dynamics of multi-component inks in paper and contribute to the understanding of the link between ink composition, process parameters and print quality in inkjet printing.