Dynamic Surface Tension in High Speed Liquid Curtain Coating
Dynamic surface tension controls curtain coating stability and heel air entrainment, dictating run speed, defect rates, and operational packaging costs.
DIN 55660-2
Standard Method
Measurement guidelines for assessing the wetting behavior of liquid coatings on solid substrates are essential for quality assurance in packaging print. The testing protocol outlined in DIN 55660-2 specifies how to determine the surface free energy of a substrate using contact angle measurements. Liquid drops of known surface tension are deposited on the test piece to measure the resulting angles.
These measurements assist in predicting how inks and varnishes will adhere to the treated surface.
Surface Energy
Solid surfaces must possess sufficient energy to allow a liquid to spread evenly. Under DIN 55660-2, polar and dispersive test liquids are deposited on the substrate under controlled conditions. Calculated components help identify whether a surface needs corona treatment before printing.
Process Control
Printers rely on these analytical results to adjust the formulation of water-based or ultraviolet-cured inks. Inadequate surface energy causes droplets to bead up, which results in pinholes, crawling, or poor rub resistance on the finished box. Applying the DIN 55660-2 methodology ensures that different batches of board exhibit consistent coatability before they enter high-speed presses.
It also helps suppliers verify the performance of specialty coatings applied to barrier boards. Maintaining a database of these contact angle measurements allows for the prediction and prevention of ink adhesion failures on challenging plastic-coated or metalized boards.