¡¡¡¡The cause of the knife wire is very complicated, involving plate making, ink, squeegee and environment, etc. It is now analyzed and discussed for peer reference.
¡¡¡¡1 plate aspect
¡¡¡¡The surface finish and hardness of the chrome plate on the plate will have an important influence on the generation of the wire. The pigment of the ink used for the gravure printing is generally dispersed in the binder in a particulate state. During the printing process, after the ink is filled with the mesh, the excess ink is scraped off by the doctor blade while constantly rubbing the surface of the printing plate. If the chrome plating on the surface of the printing plate is not sufficiently hard, it is easily scratched by the coarse particle ink to produce a knife wire.
¡¡¡¡On the other hand, if the printing press in Shanghai has poor processing of the plate cylinder during the plate making process, the layout has fine throwing or the pattern is too deep. During the printing process, the ink will remain there and cannot be scraped off by the scraper, and transferred to the printing. Irregular, very thin knives are produced on the material. Therefore, special polishing equipment and special polishing sandpaper should be used for polishing.
¡¡¡¡In addition, the drum processing precision and installation accuracy should be strictly controlled to prevent the eccentricity from exceeding the standard, so as to avoid the impact on the squeegee during high-speed printing and the generation of the cutter wire.
¡¡¡¡2 ink aspects
¡¡¡¡Ink used in plastic gravure printing, if the fineness is not enough, the pigment particles are too large or mixed with particulate impurities, will lead to the appearance of the wire. Therefore, a better quality ink should be selected, and the pigment particles should be less than 10 μm. Filtration devices should be added to the inking system and often inspected to avoid coarse particles in the ink from damaging the plates and the squeegee. If the viscosity of the ink is too large and the drying is too fast, the relative friction between the plate cylinder and the squeegee will be increased, making it difficult for the squeegee to scrape off excess ink on the plate to form a wire. Therefore, the viscosity of the ink should be controlled. For inks that are too fast to dry, use a slow drying solvent or dilute the ink.
¡¡¡¡In addition, if the ink dilution is not standardized, the use of an incompatible solvent causes the pigment in the ink to precipitate, forming large particles, thereby producing a wire. Therefore, a solvent that matches the gravure ink should be selected. If the antistatic performance of the ink is poor, or the lubricating performance is poor, it will also lead to the occurrence of the wire phenomenon. Therefore, it is necessary to strictly control whether the quality indicators of the inspection ink are analyzed.