Factors affecting the suitability of ink in newsprint printing

China's newsprint is divided into A, B, C, and D grades according to quality standards. Among them, grades A and B are applicable to high-speed web offset presses, while color newspaper printing is generally performed on high-speed web presses.

Ink absorption

1. The Effect of Newsprint Paper's Ink Absorption on Printing Quality of Color Newspapers

The color newspaper is generally printed on a high-speed rotary offset press. Because of its fast printing speed, newsprint is required to have relatively strong ink absorption, that is, the ink is dried faster on newsprint.

There is no paint layer on the surface of newsprint, which is relatively loose and has strong ink absorption. Drying of the ink is mainly accomplished through the permeation of the solvent. After the ink is transferred to the paper surface, the solvent therein rapidly penetrates into the paper, and the ink is quickly fixed and dried on the paper surface. However, if the newsprint is too loose, the ink absorption is too strong, and the viscosity of the ink used is low, the printing pressure is high, the ink will penetrate the back of the paper, and the phenomenon of overprinting will occur, and the thickness of the conjunctiva of the ink layer will be affected, so that the imprint cannot be The paper surface presents the color saturation, which affects the quality of the printed matter.

2. Reduce ink viscosity and improve fluidity

In the high-speed operation, this kind of drying method mainly based on penetration requires that the viscosity of the ink must be properly reduced and the fluidity must be improved. The viscosity of the ink at the time of printing is too large or too small, which is detrimental to printing. If the viscosity is too large, it will cause hair loss and powder loss, and it will also cause uneven ink transmission. If the viscosity is too small, it may cause ink emulsification, imprinting, and poor printing gloss. Unlike adhesiveness, with the increase of printing speed, the viscosity of the ink appears to increase during printing.

3. Dot increase affects print quality

From the point of view of the main characteristics of newsprint, the newsprint image has poorer definition, a smaller range of color reproduction, lower color purity, easier to lose the bright-spotted outlets, and a darker-swappable outlet, compared with the general coated paper. The range is small, flat screen is difficult to print evenly. The reason is that the degree of sizing of newsprint is too low (generally not sizing), the flow of ink is too large, and the pressure of printing is too large.