DRYING OF WATER-BASED INKS ON PLAIN PAPER

Previous studies in ink-jet printing have considered ink penetration i nto paper or ink evaporation to be effective in the drying process. In the present study, a unified approach that allows for simultaneous ev aporation and penetration during the drying process was applied. To th is end, penetration rates were measured experimentally using a Bristow tester. In addition, evaporation rates were determined from a theoret ical evaporation model that contained no adjustable parameters. It was found that for plain paper used in the office environment, the rate o f penetration was at least 20 x higher than the rate of evaporation. A ccordingly, ink drying is determined mainly by penetration, and penetr ation curves alone are sufficient to predict the dry time or ink disap pearance on a plain paper surface. In practice, this is illustrated by ink-jet print quality on plain papers of various sizing treatments. T he sizing level needs to be adjusted according to the desired ink-jet image. That is, full-color printing requires penetration rates suffici ent to accommodate each of the process inks applied without: color ble ed or other ink-to-ink, interaction processes. This may be at expense of character and line print deterioration due to fiber swelling in mon o-color printing.