After the tinplate has been treated by the inner coating and outer coating process, it can be printed on the machine. Because the tinplate surface is smooth, the adhesion performance is low, and it has a certain hardness and thickness, offset printing is generally used for tinplate the tin cans printing. The printing principle: oil and water are incompatible. , Dot conformation and color formation, selective adsorption. Tinplate lithographic printing is basically the same as sheet-fed offset printing, but due to the particularity of tinplate, tinplate printing is also different from ordinary offset printing, mainly in the following aspects:
(1) The drying and heat resistance of the printing ink for metal cans, the curing of the printing ink for the tin cans must be heated and dried, so the white ink after heating is required to remain unchanged, not yellow, the color ink will not fade, not change color, and the varnish will not lose its gloss.the tin cans printing ink generally needs to be fixed at 150 degrees Celsius for 10 to 12 minutes. Therefore, the heat resistance of the ink for metal can packaging is more important.
(2) Metal can packaging has process resistance, tinplate products need to go through processes such as stamping, punching, bending, flanging, and sealing, so the ink layer on the surface of the tinplate should have a strong structure, and the printing ink for metal cans is required to have good adhesion and flexibility. properties, surface hardness and impact strength.