printing on tin plates also uses the physical properties of water and ink to repel. Using printing pressure, the print tin plate sheet and text are transferred to tinplate through a blanket, which belongs to the principle of lithographic offset printing. Because electrolic tin plate has special physical and chemical properties and reprocessability of printed matter, electrolic tin plate printing process is greatly different from ordinary offset printing.
Electrolic tin plate printing requirements
(1) Electrolic tin plate printing requires ink to have good adhesion and mechanical properties
As electrolic tin plate printings are eventually made into food cans, toys, metal photo frames, and barrels and cans of chemical products, they need to be cut, bent, and stretched. Therefore, printing inks are required to have good adhesion to print tin plate sheet and corresponding machinery. performance. In order to improve the ink adhesion, the print tin plate sheet needs to be white-primed first before printing. White is the base color of all pictures and has a very high brightness. After adding other high-energy hue, the brightness of each hue can be increased to form a gradation.
(2)Electrolic tin plate printing requirements for white ink
The tinplate surface is silvery white (or yellow) with metallic luster. Before printing on tin plates the color graphics, the surface needs to be painted white or printed white. Due to the limitation of the ink covering ability, the monochrome machine often needs to print 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 no discoloration at high temperature resistance. 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, good flexibility and impact resistance.