In the PET cartridge printing process, the dried ink has a lighter ink color than the fresh ink just after printing. The main reason for this problem is the discoloration caused by the penetration of the ink on the surface of the PET cartridge during the drying process and the oxidation of the conjunctiva. The letterpress ink is mainly osmotic drying, and the ink layer is relatively thick. At this time, it takes a while for the infiltration and oxidation of the conjunctiva to dry. In the PET plastic box printing, the ink color should be controlled to be slightly darker than the original printing sample ink color. When the ink is dry, it will meet the requirements of proof ink color. 

In practice, all PET cartridge printing inks will have different degrees of discoloration and discoloration after they encounter light. The faded color ink fades and the discoloration is serious after the light has been irradiated for a long time. The actual PET plastic box printing in the transfer of ink, it should try to use good lightfastness performance; At the same time in the deployment of ink should also consider the consistency of the lightfastness of several colors of ink. The same blue ink, indigo blue than light blue, peacock blue light, not easy to change color. If you add a little more white ink color more vivid. If you use peacock blue and chrome yellow ink, it will fade, change color, and yellow over time.