Mechanical Ink Set off Dynamics in Printed Web Rolls
Optimize roll winding tension and UV cure density to eliminate mechanical ink set-off and hold specific photoinitiator migration below legal regulatory limits.
Corona Treatment Surface Energy
Meaning
Surface tension measured in millinewtons per meter quantifies the capability of a polymer substrate to accept inks, coatings, or adhesives. Corona treatment surface energy defines the chemical potential of a material to develop covalent or polar bonds by increasing the concentration of hydroxyl and carbonyl groups on the treated side. This metric establishes the compatibility between a low-energy nonpolar film such as polypropylene and a high-energy liquid medium.
High values indicate better wetting and adhesion whereas low values result in dewetting or delamination.
Processing Baseline
Converters manage this property during the extrusion or lamination stage to ensure the film reaches the required dyne level before downstream printing or bonding. Producers adjust the discharge power of the electrodes to align the output with the specific requirements of the adhesive formulation or ink system. Drift in discharge power leads to inconsistent bond strength across the width of the film, which frequently causes catastrophic failure during final converting steps.
Moulders and extruders monitor this variable to prevent the scrap generated by incompatible surface chemistries.
Material Specification
Resin manufacturers define a nominal surface tension range for their base polymers, yet the actual value fluctuates based on the presence of additives or slip agents. Virgin material typically maintains higher consistency than regrind due to the lack of contaminants or degraded polymer chains that migrate to the surface. A datasheet provides a target range, but the value a processor holds across a production run depends on the age of the treatment equipment and the gap between the electrodes.
Treatment Economics
Optimal bond strength depends on maintaining a stable surface energy level throughout the machine cycle to minimize the risk of secondary bonding failure. Variations in the treatment level often force a reduction in line speed to prevent coating defects, which adds significant overhead to the production process. Strict control over the discharge voltage reduces the need for expensive chemical primers or adhesion promoters that otherwise add cost to the material structure.
Higher energy levels provide the necessary surface reactivity to ensure reliable adhesion for demanding industrial applications.