The effect of paper performance defects on printing

Paper is a collective name for paper and cardboard. It is composed of plant fibers, fillers, pigments, and rubber compounds. 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, in terms of paper, the main raw material, what are the impacts of its quality 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, the amount of ink needed to affect the paper, so that the thickness of the ink film on the blanket will be different, will result in uneven ink printing, printing and graphic network points, mechanical network points increase. Second, due to the poor smoothness of the paper, it affects the uniformity of the paper's ink, resulting in printed texts and flowers. Made a virtual, and there are serious network loss.

Second, the paper's compression deformation characteristics of the printing

For printed paper, it is not only necessary to have good compression deformation, but it is suitable for performing multi-color printing, and has the characteristic of recovering quickly after the pressure is removed. 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. The ink is evenly 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.

The common problem is that in the printing process, if the surface of the printing paper is poor, the surface of the paper is separated from the ink blanket, and the separation force of the ink is greater than the binding force between the particles on the surface of the paper, and the graphic edge of the print will appear. The phenomena of white edges or inaccurate prints, false hairs, etc., are the phenomenon of pulling in printing. The impact on printing is mainly twofold:

1. Caused part of the graphic pollution. Mainly reflected in: 1 after the flakes of paper particles, due to not stained with ink caused by white spots. 2 is due to paper powder or fine paint coating caused by pollution.

2. The number of cleaning blankets and ink rollers in offset printing increases. 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 pH of the fountain solution is 4.8-5.2. Due to the different acidity and alkalinity of the paper used for printing, different phenomena may occur and have 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. From the results of various types of paper that are printed at ordinary times, the greater the acidity, the faster the ink is dried. This is because the acidic paper absorbs the desiccant in the ink, thereby inhibiting the effect of imprinting the conjunctiva. On the contrary, 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 printing, the product part of 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.