In the offset printing process, the interaction between the paper and ink and fountain solution variables as machine components and printed materials, these variables affect not only the offset printing process, but also affect the printing quality. Therefore, must continue observation and analysis, can make the normal printing process. In this paper, the printing process imprinted shallow factor analysis.

Packing blanket on paper and ink residues

In the offset printing process, causing imprinted variable shallow for many reasons, but the main reason is the accumulation of blanket on paper and ink residues. Generally speaking, after washing the blanket around the start printing to 1500 will produce the phenomenon of accumulation, the accumulation effect is mainly affected by the following several aspects of the influence.

Effect of viscosity on the accumulation of sticky ink 1

Ink viscosity dry sticky viscous and wet and sticky sluggish, dry adhesive viscosity can be understood as ink does not contain fountain solution composition showed the viscosity; wet and sticky viscosity can be understood as printing ink containing fountain solution after the viscosity. Viscosity viscosity in batch printing process is change of, when the ink viscosity lower than paper-based hair loss limit, in the printing and imprinting both dissatisfied with not swell, not easy to produce paper wool accumulation phenomenon; when ink viscosity viscosity is higher than paper hair loss limit, imprinted in the printing process will more and more precipitous. Because of the ink viscosity is high, many small paper wool from the surface of the paper is to pull down the lint accumulate in the rubber blanket. In addition, the paper surface a little loose small particles (paper powder), small particles is also very easy to detach from the paper is adhesion in mackintosh ink part, the formation of a deposit.

In the beginning of the printing, washing blanket soon, normal fountain solution of quantity, graphic part (dot, line, field) the amount of ink is 100% transfer to paper. And when printing to 1500 after or in the lubricant is not normal, blanket ink to produce accumulation phenomenon, through the high magnification micrographs observed more obvious. Transfer to paper outlets, the diameter of the damaged, and intermediate node has no ink white dots. Therefore, dot appear pale, suggesting that reduced the amount of ink to the paper transfer. If don't wash blanket or correct adjustment of fountain solution and ink quantity, the blanket on the accumulation of paper wool, paper powder and ink residues will more and more, the imprinted will continue to shallow, paper printed on the Internet without ink part will further expand, including the halftone prints shallowing trend more obvious.

Effect of fountain solution on the accumulation phenomenon

(1) effects of fountain volume on viscosity of ink

From the above, the ink viscosity is divided into dry and wet viscosity viscosity two. The dry wet viscosity viscosity is low, because the water reduces the viscosity of the ink. Therefore, have a direct impact on the ink fountain solution viscosity, which has a direct impact on the accumulation phenomenon. Under normal circumstances, ink viscosity viscosity decreases with the increase of amount of fountain solution, but by ink types, models and roller temperature factors influence, also has other experiments show that ink sticky viscosity with the increase of amount of fountain solution and not always reduce. Therefore, we must pay attention to observation and adjustment.