Converters of blown and cast film, food packaging material, plastic bags, tapes and labels, and an ever increasing number of specialty items, are successfully using corona discharge treating for web surface preparation. In order to print, bond, or laminate these materials, it is often necessary to modify the surface of the web from its virgin state. The ability to improve its stacking, printing, adhesive, bonding and laminating characteristics has made possible much of the progress and growth of the plastics and packaging industry over the last 50 years. Corona treating is a proven technology, and our modern systems are efficient and cost effective.
Corona discharge is a continuous plasma of ionized particles. This ionization is formed in the air gap between a high voltage power source and the resistance of an electrical insulating material. As the surface of the material facing the electrode is exposed to the corona, the energy modifies the molecular structure of the web surface.
The degree of modification is generally determined by measuring the surface tension of the material. Tests are based on ASTM standards and read in dynes per cm. It is said that the surface tension is increased and therefore, the "wetability" is increased.
Basically, the process works by exposing the web material, in line, to the energy of an electrical corona discharge. The energy changes the molecular structure of the web surface so that it will more readily accept inks, adhesives, and laminates. This improved bond strength can be measured by standard ASTM surface tension tests.
Solo Systems, Inc.