Three Ink Frequent Failures in Printing Process

Pulling paper

During the printing process, the graphic part of the newspaper, especially the high density dark tone area, often appears that some of the paper fibers are pulled up.

Paper pull phenomenon and printing paper powder off. The hair loss phenomenon is fundamentally different in terms of formation reasons, production mechanisms, and solutions. The paper's flaking and linting are the fibers or filler particles that have fallen off the surface of the paper during printing, and are piled on the blanket's graphic to make the printed picture and headline appear "snowflake" under the magnifying glass, titled " "Snowflake" is relatively smooth and there is no obvious phenomenon of fiber being pulled up. The result of pulling the paper is that the fibers on the surface of the paper are pulled up. Its formation is mainly related to the viscosity of the ink and the tightness of the paper.

1. Ink viscosity

The viscosity of ink refers to the force that prevents the thin layer of ink from separating when the ink film is separated. The viscosity of the ink is very important to ensure the smoothness of the printing process and the stability of the printing quality. The ink is transferred from the ink roller to the other ink roller on the printing machine, from the ink roller to the printing plate, from the printing plate to the blanket, from the blanket to the paper, and the ink layer needs to peel once during each transfer to strip the ink. The force required for the layer is related to the viscosity of the ink. The greater the viscosity of the ink, the greater the force required to peel the ink layer. Due to the inhomogeneity of the ink transfer, if the ink is too viscous, the surface of the paper is easily peeled off by the ink film at the time of printing, that is, the paper is pulled. Ink mills are generally adjusted by the addition of a diluting solvent or mineral oil; printing plants can be adjusted by adding a suitable amount of viscosifier or No. 6 varnish. In addition, gelation of the ink occurs during the printing process will appear to pull the hair, the ink must be re-dispersed processing can be resolved.

2. The tightness of the paper

Pulling paper is also related to the tightness of the paper itself. In the production of paper, the tightness of the paper and ink absorption are a contradiction. If the tightness of the paper is too large, the ink absorbency will be reduced; if the paper has a loose texture, paper pull-out may occur easily.

In addition, in the printing process, if the temperature of the shop is too low, the viscosity of the ink becomes large, which may cause the paper pulling phenomenon to increase at the time of printing.