Corona treatment for better adhesion, coating, printing, ...
What is a corona treatment?
Corona treatment can be seen as a high frequency discharge that improves the adhesion of a plastic surface.
The oxygen in the air serves as the raw material for this oxidation. This reaction is initiated by high-energy electrons in the discharge gap, which cause bond dissociations on the plastic surface. As a result of the oxidation reactions, polar groups containing oxygen are implemented in the surface, resulting in improved wettability of the surfaces and in most cases also improved bonding on the plastic surface.
A typical corona installation
A typical corona treatment system generally consists of one or several high-voltage electrodes arranged at a distance of between 1 to max. 12 mm from a grounded roller. If a high voltage is applied to the electrodes, a corona discharge occurs in the gap between the electrodes and the roller, and a plasma is formed.
The electrodes and/or the roller are covered with a non-conductive barrier (e.g. ceramic, quartz or silicone), which has also given rise to the term barrier discharge. If a plastic is guided over the grounded roller through the discharge gap, its surface becomes oxidized when this is done.