The printing of plastic film is different from the printing of paper. In addition to the pretreatment mentioned above, another problem is that the surface of the film is smooth and the ink cannot penetrate. Although the surface of the paper looks smooth, in fact, the surface is not smooth and can allow the ink to penetrate, which is conducive to the rapid drying of the ink into a film and the adhesion of the ink to the paper surface. When we choose the ink, we have to consider the following factors.
(1) Thermal distortion point and heat resistance when drying ink is selected. It is necessary to consider whether the maximum drying temperature of the ink is suitable for the temperature that the plastic can withstand.
(2) Solvent resistance Solvents that have a certain solubility in plastic films can help the adhesion of inks to plastic films, but if the effects are strong, the mechanical properties of the films may be reduced.
(3) Plasticizers and other additives Some plastic films contain a certain amount of plasticizers and other additives. These materials can often migrate to the surface of the plastic film and eventually soften the ink and break the bond.
(4) Other factors The rigidity, brittleness, dimensional stability and expansion coefficient of plastic film will affect the durability of ink adhesion.