When the surface strength of the whiteboard paper is poor, the phenomenon of falling powder, lint, blistering and peeling occurs easily during printing. Falling powder refers to the fact that the paper surface falls off the powdery material, such as paint, fillers, pigments, etc., from the paper surface. Lint off means that the fibers on the paper are peeled off from the surface of the paper during the printing process. Paper blistering and peeling refer to the fact that under the action of external forces such as peeling force and ink sticking force, the surface layer of the paper is detached and the battering or peeling occurs due to the splitting of the paper coating, the surface layer and the underlying fibrous structure during the printing process. . From a print quality point of view, the use of paper with high surface strength and good quality is the best choice for avoiding the problems of powder falling, pulling, blistering and peeling on the paper surface and improving the printing quality of the product. However, what kind of paper is used for printing is often not unilaterally determined by a printing factory. Some common products, customers only require the use of low-end white paper to print. This requires that some necessary measures be taken from the printing process in order to prevent the occurrence of printing quality failures. According to the experience of the printing production process, the following measures can be taken for the paper with poor paper surface strength to reduce or avoid the occurrence of powder failure, nap, blistering, and peeling quality failures.
1, adjust the viscosity of the ink. Papers with poor surface strength on paper, if printed with high-viscosity inks, are most prone to powder failures, naps, blisters, and peeling quality problems. In this regard, additives suitable for the printing process conditions may be selected to adjust the flowability and viscosity of the ink in order to reduce the adhesion and stripping tension of the ink layer to the paper surface during the printing process.
2, adjust the printing pressure. If the printing pressure is too light or uneven, the ink layer on the plate cannot be completely and evenly transferred to the surface of the paper, and the printing defects of the printing are likely to occur. However, if the printing pressure is too high, the coating layer and the fiber structure on the paper surface are easily destroyed, and powder falling, linting, blistering, and peeling quality defects are likely to occur. Therefore, the use of uniform and appropriate printing pressure is an important condition for good ink transfer, and it is also one of the technical measures to prevent the occurrence of undesirable problems.
3, adjust the printing speed. In the daily production, if the cardboard with poor surface strength is printed at a higher speed, the phenomena of falling powder, pulling hair, blistering and peeling quality will be obviously exacerbated. On the contrary, if the speed of the machine is lowered for printing, this failure phenomenon will be significantly reduced. This is because the printing speed is high, and the peeling tension during the printing process is also large. In this way, the adhesive ink layer on the printing surface is not quickly, evenly and completely absorbed by the paper surface during printing and separation, but it is easy to put on the paper surface. The partial coating or fiber pulls off. Therefore, paper with poor printing surface strength should be printed at a lower speed, which is beneficial to reduce or avoid the occurrence of powder failure, nap, blistering, and peeling quality failures.
4, choose the right machine for printing. For a paper with poor surface strength, what structure of the printer is used for printing has a great influence on the printing quality. For example, the letterpress process is used as an example. If a flat and flattened machine is used to print, the ink layer on the print sheet and the plate surface are in contact with and separated from each other at the same time. Thus, the greater the separation area, the greater the tension when peeling. The coated layer or fiber on the surface is easily pulled off. In a circular press or circular press structure, the contact between the printed sheet and the ink layer on the plate is linear, and the tension when the printed sheet is peeled off after absorbing the ink is also small, and it is not easy to destroy the paper surface. Therefore, for the paper with poor surface strength, printing with a circular press structure will help improve the printing quality of the product.
5, a reasonable arrangement of printing color sequence. The reasonable arrangement of the printing color sequence is an important part of preventing the paper from falling off or fluffing. Therefore, for the paper with poor surface strength, a small layout should be printed first and a large layout should be printed first; first, the low viscosity printing ink should be printed. Large ink (non-color overlay printing plate products). If multi-color printing is used, if there are extra color groups, the front color group may not be used, so that the printed sheets can be left empty past the previous color group, or the blank sheet can be imprinted or "overwatered" by the preceding color group. This can greatly reduce the print off or pull the hair phenomenon.
6, the paper with poor surface strength, adjust for printing small products. For some paperboards with poor surface strength, despite various methods, they still cannot solve the problems of powder and paper blistering. This is because the adjustment of the ink viscosity and the peeling tension is, after all, limited, and there is no certain sticky ink, and it is difficult to achieve normal printing. Therefore, according to the characteristics of printing products, choosing the right cardboard for printing is also one of the important measures to prevent quality problems.
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