Pre-Press Processing Of PET Film

After printing, plastic films are not only required to have bright colors, rich layers, and strong three-dimensional printing effects.
The result is that the printing ink must be firm and the ink layer must not fall off or fade. However, there are many types of plastic films used for printing, and their surface properties vary greatly due to different factors such as molecular structure, polar groups of the substrate, degree of crystallization, and plastic stability.

These factors have a great influence on the bonding fastness of printing ink. Therefore, before printing, it should be determined whether surface treatment is required based on the surface characteristics of different plastics. For example, films such as polyvinyl chloride (PVC), nylon (PA), and polystyrene (PS) have polar structures and do not require surface treatment before printing. Films such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer are basically non-polar polymers. They have high chemical stability, low surface tension, and are not easily wetted by most inks and solvents. During the processing of polyolefin plastics, in order to make the film easy to open and have anti-static, anti-aging, anti-ultraviolet radiation and other properties, various additives must be added.

However, after film formation, these additives will slowly migrate to the surface of the film, reducing the bonding strength between the film and the ink.In order to increase the surface tension of the film and improve the bonding strength between the film and the ink, these films must be surface treated before printing.