Requirements for white ink
The tinplate surface is silvery white (or yellow) and has a metallic luster. Before printing color graphics, the surface needs to be painted white or printed white. Due to the limitation of ink coverage, monochrome machines often need to be printed white twice, and its whiteness Up to 75%. Whiteness, as an important indicator of the quality of tinplate printing products, requires white ink to have a good binding force with the primer, not yellowing after high-temperature baking, and not discoloring at high temperature. Priming tinplate can increase the adhesion to tinplate and have a good binding force to white ink. The commonly used primer is epoxy-amine based, with light color, no yellowing and aging after repeated baking, and good flexibility and impact resistance.