Paper is the collective name for paper and cardboard. It consists of plant fibers, fillers, pigments, and rubber. In the packaging printing process, to ensure the quality of printed products, there should be five major factors: people, machines, materials, methods, and rings. Then, paper is one of the five major factors - the main ingredient in the material. What impact does the paper quality issue have on printing?
First, the effect of poor paper smoothness on printing
Smoothness refers to the degree of flatness of the paper surface, which depends on the topography of the paper surface, reflecting the surface structural characteristics of the paper. In order to obtain a good print product quality, the smoothness of the paper is a necessary condition. In the printing process, the degree of contact between the surface of the paper and the surface of the ink-filled blanket affects whether the transfer of ink is comprehensive and whether the graphic is clear. First, due to the poor smoothness of the paper, it affects the amount of ink required for the paper, and the thickness of the ink film on the blanket will be different. This will increase the unevenness of the ink color of the prints, resulting in the enlargement of the printed image points and the increase of mechanical dot gains. Big. Second, due to the poor smoothness of the paper, it affects the evenness of the paper's ink, causing the printed products to show signs of faintness and weakness, and there are serious dot losses.
Second, the paper's compression deformation characteristics of the printing
For printed paper, not only must have a good compression deformation, but also suitable for a number of color printing, after the pressure is removed, there is a fast recovery characteristics. This is because in the printing process, the paper is deformed under the effect of printing pressure, which can produce a buffering effect, and the paper and the blanket cylinder are in good contact, so that the ink can be uniformly transferred. If the printed paper used has only a high compression ratio and does not have a high elastic recovery rate, in multi-color printing, after many times of compression and deformation, it cannot be quickly recovered, so that the paper becomes larger or shrinks, which will seriously affect the printed products. Overprint quality.
Third, the poor surface strength of paper on the impact of printing
The surface strength refers to the bonding strength between the surface fibers of the paper, the size, the filler, or between the paint particles on the surface of the paper, and between the coating and the paper base. In the printing process, if the surface of the printing paper is poor, the surface of the paper is separated from the ink-covered blanket. The separation force of the ink is greater than the binding force between the particles on the surface of the paper, and the edge of the printed matter may see the white edge or Inaccurate printing, false printing, and so on, this is the phenomenon of skeining in printing. The impact on printing is mainly twofold:
1. It caused pollution in the graphic part. Mainly reflected in: After the paper particles are peeled off, the white spots are caused by no ink. â€¢ It is due to contamination caused by paper powder or fine coating.
2. The increase in the number of blanket and ink roller cleaning during offset printing. Due to the poor surface quality of the paper, it is easy to lose material and powder, and the number of cleaning blankets is significantly increased, which greatly affects print production.
Fourth, the paper's acidity and alkali effect on printing
During the printing process, the normal range of the pH of the fountain solution is 4.8 to 5.2. Due to the different acidity and alkalinity of the paper used in the printing, different phenomena will occur, causing different effects on printing. The acidity of the paper can cause corrosion and sticking of the printing plate, which directly affects the drying of the oxidized conjunctiva of the print. According to the results of printing different papers at ordinary times, the greater the acidity is, the faster the ink is dried. This is because the acidic paper absorbs the desiccant in the ink and inhibits the effect of imprinting the conjunctiva. Conversely, the paper is alkaline, alkaline substances in the paper will be sent to the water tank, and with the fountain solution in the tank, and directly affect the control of the PH value, so that the ink emulsification, resulting in some of the printed product on the dirty, affect product quality.
Because paper has a great influence on printing, when the printed paper is used, it is necessary to strictly inspect the smoothness, compression deformation characteristics, surface strength, and acidity and alkalinity of the paper, so as to prevent printing paper from affecting printing. Quality of products
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