Plastic packaging bags are usually printed with various plastic films, and then the barrier layer and the thermal seal layer are combined to form a composite film, which is cut to form a packaging bag product. Among them, printing is the first production line and also a very important process. To measure the level of a packaging product, printing quality is the first. Therefore, to understand and control the printing process and quality is the key to produce soft packaging. Next Jinan Tianjin plastic bag customization factory will popularize the common plastic bag gravure printing technology for you, hope to help you!
The printing process of plastic film is mainly gravure printing. Gravure plastic film has the advantages of high printing quality, thick ink layer, bright color, clear and lively pattern, rich picture layers, moderate contrast, vivid image, strong three-dimensional sense, etc. However, gravure printing also has some shortcomings that can not be ignored, such as complex pre press plate making process, high cost, long cycle, serious pollution and so on.
Gravure printing process includes lithography and overprint
1. Table printing process
The so-called surface printing refers to printing on the plastic film, and putting the printed text and printed text on the surface of the finished product after bag making and other processes.
Plastic film "surface printing" is based on white ink, which is used to set off the printing effect of other colors. It has the following advantages:
Plastic white ink has good affinity with PE and PP film, which can improve the adhesion of ink.
The background color of white ink is total reflection, which can make printing more colorful.
The printing background color can increase the thickness of the ink layer, make the printing layer richer, and have the visual effect of embossing.
Therefore, the color sequence of plastic film surface printing is generally determined as: white → yellow → magenta → green → black.
The surface printing plastic film requires good ink adhesion, and has considerable wear resistance, sun resistance, frost resistance and temperature resistance. In recent years, some ink companies have developed special high temperature resistant alcohol soluble printing ink for steaming and boiling surface printing, which has excellent wear resistance, sun resistance, adhesion and luster.
2. In the printing process
Internal printing refers to a special printing method that uses the image reversal graphic plate to transfer the ink to the transparent substrate material to make the front of the substrate look like.
In order to get the same visual effect table printing, the sequence of printing color printing process should be the reverse side of "print a table", that is, the printing of white ink background color. From the front printing, white ink background color can play a role in frustration. Therefore, the printing color sequence in the printing process should be: Black → green → magenta → yellow → white.