Discussion on the printing adaptability of paper

Whether or not paper can be used for printing with high quality depends on the printability of the paper. The requirements for printing on paper are: the hue of the paper should reach the purity of the same texture as much as possible, the degree of dust of the paper must not exceed the allowable range, have the minimum light transmittance, and ensure the mechanical strength during normal printing, and the thickness of the paper. The tightness, structural characteristics, etc. should be the same in the same print batch. The edge of the paper should be right angle and the slope error cannot exceed ±3mm.

The smoothness of the paper: The smoothness of the paper directly determines the print quality of the print. The paper with high smoothness can make contact with the plate better during embossing, so that the ink layer on the plate can be evenly transferred to the surface of the paper. The paper with low smoothness will be uneven on the surface during printing. The uneven contact between the surface of the plate and the paper during imprinting causes uneven transfer of the ink layer to the surface of the paper. If the paper touches a paper with low smoothness, the pressure during printing may be appropriately increased during printing. Can properly make up for the phenomenon of imprints appearing on the surface because of its uneven surface.

Ink absorption of paper: The absorption of ink by paper depends mainly on the tightness of the fibers of the paper (the size of the gap). When the gap between the paper fibers is small, due to too little deuterated fibers, the effect of the fiber capillary is affected, resulting in the paper's ink absorption; if the gap between the paper fibers is too large, it will be caused by excessive absorption of the connecting material. Ink pigments are also absorbed, making prints appear through the phenomenon.

The elasticity and plasticity of the paper: In various processes such as printing and printing, the paper will undergo various changes due to the different surrounding environments. As the external force, will instantly change their shape and size, and when the external force stops, the paper will return to the original shape and size, this deformation process is called sensitive elastic deformation; when the paper is subjected to external force In a certain period of time, it changes its shape and size. When the external force ceases to function, it slowly returns to its original shape and size. This process of deformation is called hysteretic deformation; when the external force is cancelled, the paper remains. In the state of deformation and shape caused by external forces, it is called plastic deformation. Sensitive elastic deformation and hysteretic elastic deformation are reversible deformations, while plastic deformation is irreversible deformation.

Paper surface strength: The surface strength of the paper determines the decisive influence of the surface on the surface of the paper during printing, such as wear resistance, resistance to powder fall, and fluff resistance. When printing, in order to get a clearer dot, some ink with higher viscosity will be used. If the surface strength of the paper is not enough, it will be easy to drop powder, hair loss, and adhere to the surface of the plate; if you use a lower viscosity ink In the lithographic printing, the ink and fountain solution emulsify, resulting in dirt in the blank area of ​​the printing plate.

The moisture content of the paper: How much water does the paper directly affect the quality of the printed matter. Excessive water content will reduce the strength of the paper. Under the action of the external force, the paper fibers will be pulled out and the plastic deformation will be enhanced. The drying speed is affected; if the water content is too low, the paper will be brittle and easily damaged, resulting in static electricity. Since the moisture content of the paper has a great correlation with the surrounding environment, the humidity and temperature of the printing room should be properly arranged to maintain the balance of water content of the paper.