Theoretically speaking, to obtain good printability on plastic films, the surface tension of the film should be higher than the surface tension of the ink, and the surface should have a certain roughness to form the adsorption force.
In the plastic film, polyolefins such as PP and PE films are non-polar high-molecular materials and have stable chemical properties and small surface tension, which is lower than the tension of the ink. The ink adhesion ability is poor. Although some films have surface tensions that are comparable or even higher than the ink tension, they have a smooth surface and a small pore-free surface with low adsorption force. At the same time, various film anti-aging agents and other anti-aging agents added to synthetic resins also affect the film surface tension. The surface properties of the film degrade its printability.
There are some printability problems in most shrink films. In order to improve the printability of the film surface, the surface of the film with poor printability must be pretreated to improve the surface tension and surface adsorption force. Common methods include corona treatment, plasma treatment, chemical treatment, coating treatment and so on.