
Plastic has a majorly used as a barrier, a barrier from air & water i.e. it resists air or water from passing through:
A thumb rule says: That the surface energy of the Plastic should be 10 points more than ink or Adhesive, than only will it bond with each other. Surface Energy (energy associated with the intermolecular forces at the interface between two media the surface energy per unit area equals the surface tension. — also called free surface energy.)
Surface Energy of Plastic is lower than that of Ink, Increase the Surface Energy of the Plastic, which should be more than Ink or the adhesive. When Plastic is passed through Corona Discharge, We call it as treated surface, i.e. the Surface Energy is increased.