Drying Kinetics of Three Types of Flexo Ink and Drying Parameter Optimization
This technical paper reveals drying kinetic principles of water-based, solvent-based and UV flexo inks, analyzes heat and radiation response rules of different ink systems, and optimizes drying temperature, air volume and UV power parameters for high-speed flexo presses.
The drying efficiency of flexo ink determines the upper limit of flexo printing running speed, and each type of flexo ink follows completely different drying kinetic curves. Water-based ink relies on water evaporation, solvent-based ink depends on organic solvent volatilization, and UV ink realizes instant curing through photochemical cross-linking reaction. Blind unified drying parameter setting leads to insufficient drying or substrate thermal damage.
Water-based flexo ink drying is controlled by hot air temperature, air volume and web passing time. The evaporation rate of water-based ink is slowest below 60 degrees Celsius and rises rapidly when temperature reaches 70 to 85 degrees Celsius. Excessively high temperature over 90 degrees Celsius causes substrate shrinkage and deformation for thin film materials.
High Speed Flexo Printing Machine - Stack Flexo Flexo Printing Machine
Solvent-based
flexo ink has fast natural volatilization speed and low dependence on drying temperature. Its drying speed is mainly affected by hot air flow rate rather than temperature. Increasing hot air volume can accelerate solvent volatilization effectively without bringing thermal damage to heat-sensitive substrates. However, excessive air flow will cause ink pattern edge deformation and floating ink defects.
UV flexo ink curing kinetics depends entirely on UV radiation intensity and irradiation time instead of heat. The ink does not produce volatile gas during curing and has zero thermal impact on substrates. Insufficient UV power leads to incomplete inner ink curing and surface ink scratch defect; excessive UV power causes ink layer brittleness and reduced folding resistance of printed patterns.
Compound drying parameter matching scheme for mixed ink production: for water-based ink film printing, adopt medium temperature and high air volume drying mode; for solvent-based ink packaging printing, set room temperature with maximum air flow; for UV ink high-speed label printing, match precise UV power according to ink layer thickness.
Online drying feedback system adjusts drying parameters synchronously with printing speed. When printing speed rises, the system automatically improves drying capacity including hot air volume or UV power to match shortened drying time. This linkage adjustment ensures complete ink drying at any running speed and eliminates ink back-sticking defects fundamentally.
