With the arrival of the hot summer, the major shopping malls and supermarkets are placed on the rows of freezers, which neatly put a variety of drinks. I do not know if you have found that most drinks are canned in plastic bottles, but some drinks are not packaged in plastic bottles. Like we are familiar with Red Bull, canned Wong Lao Ji, JDB, Lulu… These drinks all have one thing in common: can packaging. So, how is this tin can printed, what are the process requirements? Iron printing is the process of printing graphics on tinplate (tin-plated thin iron plate). It mainly uses the principle of oil and water incompatibility, with the help of printing pressure, the printing plate is transferred to the tinplate by the rubber cloth, which belongs to the principle of lithography offset printing. This process has special requirements for inks. The main processes and operation points of the traditional iron printing process are roughly as follows:
1. Coating
Coating before printing. Under normal circumstances, the front of the tinplate needs to be coated and printed, the inner side needs to be coated with paint, and the iron printing products have good requirements for canning, canning and appearance decoration. According to the classification of resin coating oil, phenolic, epoxy, polyester, ethylene, acrylic, amino, etc., according to the use of the inner coating, outer coating, color coating, gloss coating, special coating and so on.
2. Platemaking
The plate making of iron printing is basically the same as that of ordinary offset printing, but because iron printing products are ultimately made of cans, iron printing plate making must meet the requirements of canning, and the basic characteristics of metal packaging containers should be understood when making plates. For example, oil cans, plate making should consider the requirements of blank resistance welding, there is a certain distance between the patterns, so that the product can be easily cut after the printing process, high frequency welds and the needs of canning, such as the battery shell. It is necessary to arrange as many pieces as possible within the specified tinplate size range, and to facilitate the cutting and punching of the battery housing. In addition, candy boxes, to understand the size of the blanking knife edge of the box cover, and accordingly leave a certain amount of leftover material, otherwise it will bring trouble to the punching of the box cover
3. Printing
After the inner coating and outer coating, the tinplate can be printed on the machine (except for special processes). Printing machine monochrome machine two-color machine and multi-color machine 3 kinds. At present, the domestic selection of imported machines is mainly the British company’s two-color printing machine and Japan’s Fuji Company’s two-color printing machine, the domestic machine mainly uses Shanghai Gauss printing Equipment Co., Ltd. monochrome printing machine. The structure of the printing machine is similar to that of an offset press. When printing, it is necessary to carry out ink balance adjustment, printing pressure adjustment and overprinting accurate adjustment. Because the tinplate surface is different from the paper, there is no capillary absorption of the paper, so when considering the color sequence, a large area of wet pressure wet multi-color overprinting can not be arranged, and only the wet pressure wet process can be implemented for the following five points. When arranging the color sequence, it is generally necessary to comprehensively consider the main tone of the layout, the accuracy of overprinting and the pros and cons of the operation, and analyze the specific characteristics of the product itself and the performance of the machine.
4. Glazing
After the completion of all the colors, the surface of the printing iron needs to be covered with a layer of bright oil to increase the gloss of the surface of the printing product, but also to improve the hardness of the surface of the product, so that the printing ink layer has a certain flexibility and corrosion resistance.