Surface Energy
Interfacial fluid mechanics dictates the degree to which liquid formulations spread across solid packaging substrates during printing processes. Evaluation of flexographic ink wetting determines whether water-based or solvent-based inks form uniform liquid films on paperboard and polymer films. Liquid spreading occurs when the surface energy of the substrate exceeds the surface tension of the liquid ink.
The mechanism fails to describe drying or curing behavior after liquid film deposition is complete.
Liquid Spreading
Surface energy differences govern contact angle formation between printing fluid droplets and board surfaces. Optimizing flexographic ink wetting requires corona treatment or chemical primers on non-porous polymer films to elevate surface energy above forty dynes per centimeter. Low surface energy causes ink beaded drop defects, retarding ink film transfer from anilox rolls to printing plates and substrates.
Dynamic wetting dynamics during high-speed press operation dictate ink transfer efficiency and dot gain consistency. Surfactant additions lower ink surface tension, enabling smooth coverage on hydrophobic paper coatings without inducing foam formation in ink fountains during long printing runs.
Ink Adhesion
Film uniformities establish the physical bond between cured ink solids and underlying packaging substrates. Defective flexographic ink wetting creates pinholes and void areas in printed graphics, reducing rub resistance and visual clarity. Substrate surface preparation remains essential for maintaining print quality across high-speed packaging converting lines.
