Today, Hong Kong Dragon Intelligent will share with you the reasons for static electricity generated during the printing process of screen printing machines: especially in the screen printing process, when the network template pops out of the substrate, the ink in the network pattern part will also form fluffy spider silk with the screen, which will be pulled up from the substrate and float. As the screen continues to rise, this spider silk drifts with the wind and spills back and forth on the substrate, making the surface of the substrate dirty and the edges of the pattern less sharp. This phenomenon is very annoying and no printing personnel want to see it. This is an electrostatic phenomenon. What's going on with those static electricity?
From an atomic perspective, all neutral materials, such as plastics, paper, and other insulating materials, are positively charged atomic nuclei in each atom, which interact with negatively charged electron clouds around them. When materials are separated by frictional contact, electrons in the insulating material will dissociate to the surface of the material.
In optical disc printing, the so-called screen printing is the process of transferring ink to the substrate through the relative movement of the network version and the ink scraper under a certain scraping pressure. Screen printing (silk screen) and ink scraper (polyurethane adhesive scraper) are insulators. In screen printing, they undergo relative scraping and friction in position, especially under low humidity, which can generate static electricity and affect the distribution of surface charges on the substrate. Especially for insulation materials such as PC substrates used for optical discs, PET substrates used for touch opening, and PVC used for names and logos, static electricity can be generated during screen printing operations if not careful. For example, when screen printing film switches with decorative ink, the PET base will not stick a layer of PVC on the surface after production, and the surface will not be scratched. However, before cutting the silk screen, the protective film must be removed. Usually, some operators will quickly remove the protective film when tearing it off. Who knows, at this moment of rapid removal, static electricity will be generated on the surface of the PET sheet during the rapid separation of the protective film from the PET sheet, especially at low humidity. Therefore, there are quality issues such as flying hairs on the ink at the edges of the printed text on screen printing, and ink threads of plush patterns sinking on transparent PET sheets. This is a typical example that once caused great confusion for the screen printing workshop of film switch units. Due to the presence of static electricity, the production difficulties caused by static electricity during the printing process are significant.
Sometimes, the presence of static electricity is also related to the printing process not meeting the requirements. When the humidity is low and the ink solvent is insufficient, on the one hand, static electricity cannot be transmitted through moisture due to low air humidity, resulting in low ink solvent and high viscosity. The ink itself naturally produces drawing; If the printing speed is increased, the strong friction between the ink scraper and the network will generate static electricity. Especially under the conditions of high tension network versions, the pressure of polyurethane adhesive scraping the screen is high and the scraping speed is fast, which can cause static electricity. This is why screen printing machines generate static electricity during the printing process.
