In plastic PP, POM, etc polymer adopts the way of screen printing.Screen printing and screen printing, the same principle is also similar, it is using silk screen ink plate picture and text part of the mesh, the graphic part of the mesh is not through the basic principle of ink to print.In silk screen printing on the plate at one end into the ink, scrape printing scraper ink on silk screen printing position a certain pressure, moving in silk screen plate at the other end at the same time.Ink scraper in moving from the graphic part of the mesh extrusion on the substrates.
In practice, phenolic resin, alkyd and other types of ink or paint though easy to operate, but its adhesion, hardness and wear resistance are difficult to meet the requirements.Recommended acrylate, nitrocellulose, polyurethane or epoxy resin and other types of ink or coating has high adhesion to ascend.
PP and POM is with high crystallinity and low surface tension of non-polar molecule structure of polymer materials, in their molecular structure and there is no such as carbonyl and carboxyl, hydroxyl polar groups, etc., therefore more suitable for screen printing.But for polyolefin material, in order to ensure that the ink film adhesion, must be to deal with plastic surface.
Generally speaking, the current popular there are two ways: one way is to improve the plastic solid surface tension, the method is under the existence of photosensitizer, use ultraviolet light to make plastic surface low molecular layer molecular weight value, increase the tension of a solid surface.Another way is to make polyolefin plastic surface oxidation, make its surface generate some polar groups such as carboxyl, hydroxyl and carbonyl group, in order to improve the critical surface tension of the plastic surface, improve the printing ink and coating on the surface of plastic adhesion performance, can use flame, chromic acid mixed liquid, such as discharge oxidation and ozone oxidation treatment method.
This step is necessary, in theory, also cannot cancel.As for the PP handle water treatment process due to the complex, can consider to use other methods instead of, but the surface treatment of this step is very necessary.
(Gold Printing Group) |
