Pore Network Structure Modulating Offset Ink Vehicle Absorption Rates
Narrow coating pore throats below 0.05 micrometres maximize capillary pressure, driving rapid ink vehicle separation and set speed on offset press.
Offset Ink Setting
Immobilization Phase
The initial solidification of a printed ink film on paperboard occurs as the low-viscosity solvent carrier separates from the resin matrix and drains into the substrate. This transition, called offset ink setting, is critical because it determines how quickly a printed sheet can be handled without smearing or set-off. Managing this rate prevents the freshly printed sheets from sticking together in the delivery pile.
Capillary Force
Capillary forces in the paperboard’s coating draw away the light mineral oils to consolidate the ink film. As these oils migrate into the porous structure of the board, the concentration of resin and pigment on the surface increases rapidly. This causes the liquid ink to transform into a semi-solid, tack-rich gel that resists light contact.
If the setting is too slow, the ink remains wet and smears on the next sheet, while excessively rapid setting can drain the binder too early and cause chalking.
Production Efficiency
Print shops optimize their run speeds by matching the absorption characteristics of the board with the setting speed of the ink. Adding driers or adjusting the temperature of the pile can also accelerate the setting time on press. This careful balance keeps the production line moving without causing surface scratches on the printed pieces.