Tinplate printing process and requirements
Tinplate tin cans need to print the tinplate before the production, and then cut the stamping. The tinplate printing is commonly known as the printing iron. It is the physical property of using water and ink to repudiate. With the printing pressure, the printing plate is transferred by the blanket. On the tinplate, it belongs to the principle of lithographic offset printing. Due to the special physical and chemical properties of tinplate and the reworkability of printed matter, the printing process is quite different from ordinary offset printing. The printing iron production line generally consists of feeding equipment, offset printing unit, coating unit, drying room and film collecting device. The process characteristics and requirements of each process are as follows:
1. Internal coating (over oil)
Packaging containers made of tinplate, depending on the characteristics of the contents, usually need to be coated with a certain coating on the inner surface of the container, commonly known as gold oil or varnish, to prevent the contents from eroding the tank wall and contents, which is conducive to long-term storage. . For confectionery boxes, in order to prevent post-processing curling, the iron is rubbed and rusted, and a decorative coating is also applied to increase the appearance. The performance of the coating in food can not only have corrosion resistance, good adhesion, flexibility, non-toxic, odorless, in line with food hygiene and safety requirements, but also must have the heating and internal coating of high-frequency resistance welding in the post-process. Local high temperature heating, and high temperature cooking at 121 ° C after canning without fading and loss of light. Generally, phenolic resin coating, epoxy-phenolic resin coating, acrylic resin coating and aluminum powder coating are applied, and the inner coating type and coating thickness are generally selected according to the characteristics of the contents.