A print dryer is a piece of equipment needed when printing with heatset inks, which are a type of ink that dries and sets only with the application of heat. Essentially, its primary function is to apply sufficient heat to the printed material to cure the heatset inks, making the print permanent and smudge-proof.
The necessity for a dryer arises specifically when using heatset inks because, unlike some other ink types that dry through oxidation or absorption, heatset inks require a specific temperature to initiate the drying and setting process. Without a dryer applying this heat, the ink would remain wet.
Types of Print Dryers
Based on the methods used to apply heat, print dryers commonly found in printing operations include:
- Open-flame dryers: Utilize direct flame to heat the printed web.
- High-velocity hot-air dryers: Use jets of very hot air blown onto the printed surface.
- Combination dryers: These units combine different methods, such as a mix of open-flame and medium-velocity hot-air drying elements.
Post-Drying Process
After the printed web has passed through the dryer and the heatset inks have been cured, the process isn't quite finished. The reference indicates that following drying, the web needed to pass through cooled chill rolls. These rolls rapidly cool the heated substrate and inks, which is crucial for stabilizing the ink and preparing the material for subsequent handling or finishing processes.
