4. Poor adhesion
Phenomenon: The printing product rubs and fades (printed plastic, aluminum).
Cause: The ink is not correct, the amount of resin in the ink is too small; the plastic is not handled well; the film is brittle and hard.
Treatment method: change the ink of the printing film, use the resin diluent while adjusting the ink; Reprocess the plastic surface. Regarding adhesion, this is a difficult problem to solve. It is generally related to the adaptability of the ink to the film. That is, the resin, solvent, and pigment system used in the ink should have greater softness on the surface of the film and also be related to the adaptability of the film to the ink. That is to say, the film surface has a greater affinity for the ink. For the ink, the polyamide resin and some other resins have a good affinity for the film, but due to the different nature of the pigments, the effects are not uniform. . The treatment of the film surface is to overcome its smooth, non-polar defects in order to increase the adsorption of the ink. Long processing time, many times, good adhesion, good printing effect with the treatment. The stronger the voltage, the better the impact effect. The voltage is at least 9000 volts, preferably 12,000 to 15,000 volts. The surface energy can be treated to more than 38 dynes/cm2, or some wax can be added to plastic during blow molding.