Mechanism of drying of water-based inks on bond papers

Water-based inks containing a glycol cosolvent, such as those used in ink jet printing, appear dry-to-the-touch on bond papers when the ink volume per unit area decreases to below the surface void volume per unit area of the paper. The drying process consists of two stages. In the first stage, the ink volume decreases by evaporation of water while in the second stage the ink penetrates the paper according to Lucas-Washburn kinetics. In this study, we have examined the relationship between these two mechanisms as well as their dependence upon the characteristics of paper. It is shown that the evaporation mechanism is extremely sensitive to the physical characteristics of the surface of the paper represented by its surface void volume per unit area. On the other hand, penetration of ink into paper is found to be strongly dependent on the chemical characteristics of paper which determine its critical penetration energy.