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Firstly, the impact of poor paper smoothness on printing

Smoothness refers to the smoothness of the paper surface, which depends on the surface morphology of the paper and reflects the surface structural characteristics of the paper. In order to achieve good printing product quality, the smoothness of the paper is a necessary condition. During the printing process, the degree of contact between the surface of the paper and the surface of the ink blanket affects whether the ink transfer is complete and whether the graphics and text are clear. Firstly, due to the poor smoothness of the paper, it affects the ink consumption of the paper. The thickness of the ink film on the rubber blanket varies, which increases the uneven ink color of the printed product, resulting in larger graphic dots and more mechanical dots in the printed product. Secondly, poor smoothness of the paper affects the uniformity of ink application, resulting in a weak appearance of the printed product and severe loss of dots.

Secondly, the impact of the compression deformation characteristics of paper on printing

For printing paper, it is necessary to have good compression deformation, be suitable for multiple reprints, and recover quickly after removing pressure. This is because during the printing process, the paper deforms under printing pressure, which can produce a buffering effect, allowing the paper and blanket cylinder to have good contact and ink to be evenly transferred. If the used printing paper only has a high compression rate without a high elastic recovery rate, then in multi-color printing, if it cannot be quickly restored after multiple compression deformations, it will seriously affect the quality of the printed product overlay.

Thirdly, the impact of poor surface strength of paper on printing

Surface strength refers to the bonding strength between the surface fibers, adhesives, fillers, or coated particles of paper, as well as between the coating and the paper substrate. In the printing process, if the surface of the printing paper is poor and the paper surface separates from the ink blanket, the separation force of the ink is greater than the bonding force between the particles on the paper surface, and white edges, false printing or weak printing will appear at the edges of the printed product, which is the phenomenon of fuzzing in printing. There are two main impacts on printing:

1. Causing pollution to the graphic part. Mainly reflected in: ① There are no white spots caused by ink on the paper particles after peeling. (2) Pollution caused by paper powder or fine paint brushing.

2. An increase in the frequency of cleaning the rubber blanket and ink roller in offset printing. Due to the poor surface finish of the paper, it is easy for material and powder to fall off, resulting in a significant increase in the frequency of rubber blanket cleaning, which greatly affects printing production.

Fourthly, the impact of paper acidity and alkalinity on printing.

During the printing process, the normal range of pH value for the dampening solution is 4.8-5.2. Due to the different acidity and alkalinity of printing paper, different phenomena may occur, which have different effects on printing. The acidity of paper can cause corrosion and adhesion of printing plates, directly affecting the drying of printed oxide film. From the results of printing different types of paper, it can be seen that the higher the acidity, the faster the ink dries. This is because acidic paper absorbs desiccants in ink, thereby inhibiting the effect of imprinting oxidation on the film. On the contrary, when the paper is alkaline, the alkaline substances in the paper will transfer to the water tank and neutralize with the dampening solution in the water tank, directly affecting the control of pH value, causing ink emulsification, resulting in some dirt on the printed matter, and affecting product quality.

Due to the significant impact of paper on printing, it is necessary to strictly inspect the smoothness, compression deformation characteristics, surface strength, acidity and alkalinity of used printing paper when it is shipped out. So as to avoid affecting the quality of printed products due to the quality of printing paper.