Tinplate cap is commonly used for packaging food, which can reduce the speed at which food ingredients are oxidized. The tinplate cap seen on the market are all brightly colored, so how is it colored? In this article, Shantou GR Machine Co., Ltd introduces the coloring method of the tinplate caps, hoping to let everyone know more about the tinplate caps.
The surface of the tinplate is silvery white or yellow, with metallic luster. The surface needs to be painted white or printed color before printing colored text and patterns. Affected by the ink binding force, it will not turn yellow after repeated high-temperature baking and will not fade after high-temperature cooking. The tinplate primer can increase the adhesion to the tinplate. White ink has excellent adhesion. Primers used commonly are epoxy amine-based, with light color, repeated baking without yellowing, non-aging characteristics, good flexibility, and impact resistance.
In addition to certain water resistance, printing color inks also have special requirements. The surface of tinplate cannot penetrate water and solvents, and needs to be dried. Therefore, the ink needs thermosetting properties and requires high pigments' tinting strength and durability. In addition to the substrate function of general offset printing inks, iron printing inks should also have heat resistance, strong ink film adhesion, impact resistance, hardness, cooking resistance and light resistance according to the characteristics of iron printing inks.
The adhesion and function of tinplate cap ink can also be said to be packaging cans if it is to make food cans. The final production of tinplate prints for food cans, toys, metal frames and chemical product cans requires cutting, bending, stretching and other technologies. Therefore, printing inks require good adhesion and corresponding mechanical functions. In order to improve the adhesion of the ink, the first requirement before printing is to plate the metal sheets with a white background. The main color of all screens is white with high brightness. After participating in other high-energy tones, the brightness of the color can be improved and the color gradation can be formed.