The quality of the print is partly due to the properties of the paper

The quality of the print is partly due to the properties of the paper!

In our printing process, the printing performance of the paper determines whether the printing process can be carried out smoothly and whether the high-quality printed matter can be obtained. The quality of paper performance is related to the quality of printed products. Therefore, to correctly understand and understand some properties of the paper, to accurately grasp the suitability of the printing process, the editor of Shanghai Printing Factory will share with you the impact of paper properties on the printing quality.

1. Surface strength

Surface strength refers to the bonding strength between the surface fibers, sizing materials, fillers of paper, or between the coating particles on the surface of the paper and between the coating and the paper base. It has a decisive influence on the abrasion resistance, powder drop resistance and lint resistance of the paper surface during printing. In order to obtain clearer dots during printing, some inks with higher viscosity can be used. If the surface strength of the paper is not enough, powder and hair loss will easily occur and adhere to the surface of the plate.

During the printing process, when the ink is split between the paper and the blanket, the peeling tension is generated due to the pulling force of the ink adhesion and the adhesion between the blanket and the paper. When the bonding strength is not enough, the paper sticking phenomenon occurs during the printing process, resulting in powder or hair loss, and in severe cases, the paper will be broken. White spots formed where the ink was supposed to be on the surface of the paper that had been glued off. The loose coatings, filler particles and fibers that stick down can cause adverse consequences: First, it will cause pollution of the graphics and texts, and more and more paper wool and paper powder will accumulate on the printing plate, which will cause the plate to paste and make the printed product. The handwriting is blurred and the picture has spots, which seriously affects the quality of the printed product; the second is that the cleaning times of the blanket and the ink roller in the offset printing increase, which reduces the printing efficiency and increases the labor intensity of the printing workers.

If the surface bonding strength of the paper is not enough, the viscosity of the printing ink must be appropriately reduced before printing, in order to reduce the adhesion of the ink to the paper, and also to prevent the surface sticking during printing.

2. Ink absorption

The so-called ink absorption of paper refers to the ability of paper to absorb ink. The ink absorption performance of paper is an important printability index that affects the quality of printed matter. The ink absorption of paper mainly depends on the tightness (the size of the voids) between the fibers of the paper. Printing paper requires the proper porosity of the paper fiber structure.

If the paper is too loose, the fiber gap is too large, and the ink absorption of the paper is too strong. There is a lack of binder in the ink layer of the ink layer, so that the pigment particles are suspended on the paper surface. After the conjunctiva is dried, the color of the printed matter is old or tarnished, and even when some imprints are rubbed, the pigment will be granular and peel off, resulting in chalking. Paper that absorbs ink too strongly may also cause print-through.

Paper's ability to absorb ink is too small, which will slow down the drying speed of the ink on the surface of the printed product, the printing speed cannot be increased, and cause the back of the printed product to be dirty, especially for letterpress printing and high-speed printing that rely on penetration drying. Printing even more. In addition, in printing, paper with poor ink absorption performance is used, and the ink absorption performance after inking is also poor.

The above is the impact of paper performance on printing quality shared by the editor of Shanghai Printing Factory. The quality of paper performance is related to the quality of printed products. Therefore, correctly recognize and understand several properties of paper.