Gravure plastic film quality control 3

When the printing viscosity is too high, resins, pigments, and other substances have poor fluidity and cannot be uniformly dispersed and accumulated, causing the blade and the plate cylinder to be damaged under high-speed operation, resulting in linear fouling. At the same time, since the resin and the like are also in a supersaturated state, a large amount of resin accumulates together and under the pressure of the doctor blade, the resin adheres to the drum (the pigment is entrained in the resin) due to the affinity of the resin to the drum, and the sheet becomes contaminated. In general, the smaller the ink printing viscosity, the less likely the dirty plate problem occurs.
2 Color misregistration: mainly due to the deviation of the diameter of the gravure cylinder; deformation of the graphic and text due to incorrect plate loading; uneven tooth spacing between the shafts, large or small gaps, or overprinting of the top teeth; Reel tension control is uneven or uneven gravure film thickness, lotus leaf edge; uneven pressure between the plate cylinder and the impression cylinder at both ends or multi-color overlay printing pressure between the printing plate is inconsistent.
3 Size deviation: Insufficient or excessive shrinkage margin. Due to the influence of the tension of the plastic film and heat drying, the longitudinal dimension of the film changes greatly during printing. Control measures: Adjust the printing tension appropriately to prevent dimensional deviation due to improper temperature setting.
4 Anti-printing (ie, biting): Anti-printing means that the ink of the previous color is overprinted onto the latter printing plate during overprinting. Cause: The ink of the previous color was not completely dried; the pressure of the second color was too large, or the speed was too fast, or the hot and cold air was bad; the substrate had poor printability. Improve the adhesion of the ink of the previous color, adjust the viscosity of the ink, increase the amount of hot and cold air, increase the drying speed of the ink, slow the speed of the vehicle, increase the ink supply of the latter color, reduce the viscosity of the latter color, and correctly arrange the color sequence of the printing plate; Reduce impression cylinder pressure, or use a softer rubber roller.
5 Whitening: The resin is insoluble, precipitated; drying is too fast. Control measures: Re-inking, appropriate slow-drying solvent. There are many problems in gravure printing. In the actual printing operation, the main reason should be carefully analyzed. It can be considered from the aspects of register control, tension control, ink control, temperature control, etc., and quickly eliminated to ensure smooth production. This requires skilled technology, timely understanding of the causes of the above common quality problems, and decisive measures to solve the problem of gravure quality of plastic film in a timely manner.
6 Incomplete pattern line: hot air is too large, the ink is easy to dry, the ink dries quickly in the mesh line, the ink is dried on the surface of the printing plate, the pressure between the printing plate and the impression cylinder is too small, and the angle of the squeegee is not ideal. The pressure on the layout is not enough; uneven unevenness of the printing plate or white spots, shallow printing plate, burr, ink adhesion; ink is too thin; printing speed is too slow. Add butanol in a timely manner to clean the printing area; adjust the pressure; adjust the angle of the squeegee and the pressure on the plate; deepen the printing plate to remove burrs; properly add the original ink; adjust the printing speed.
7 Chromatic aberration: Chromatic aberration refers to the color difference between rolls and rolls during the printing process. Cause: The viscosity of the ink is not well adjusted; the gravure cylinder blocks the plate; the printing staff does not perform properly.
8 Blocking: Printing, with the large amount of solvent evaporation, ink viscosity increases, easy to dry inside the cable; printing process, the position of the blade is far from the printing roller or the angle is not reasonable, the diameter of the roller is large or the platen roller enters When the depth of the ink tank is not enough, the hot air blown from the drying pipe affects the drum surface, which can cause serious blockage; the ink is mixed with impurities; the engraving depth of the platen roller line is not suitable; when the temperature is too high, the solvent in the ink volatilizes quickly. .
The process of gravure printing plastic film is more difficult to control, so in the printing, we must sum up some experiences to obtain our own quality control method. (Finish)