The degree of uniformity of the ink layer on the surface of color prints directly reflects the worries of product quality. Especially for multi-color overprinted packaging and decoration prints, most of them use large-area layouts as substrates, and their printing receives a large amount of ink. If you do not have a good grasp of process technology, it is difficult to print a uniform and uniform ink layer. Can not achieve the desired effect. A high-quality color-printed product should give people a visually beautiful feeling. This beauty is first felt from the brightness and uniformity of the printed ink exhibition. Some operators have insufficient experience in process practice, in order to overcome the unevenness of the ink layer and the phenomenon of flowering, they often increase the amount of ink delivery blindly to meet the bright and thick visual effect of the printed ink layer, so that the printed ink layer has occurred. The undesirable consequences of the bottom, the unclear imprint and the crystallization of the ink film are precisely the technical errors of the process operation and must be paid attention to. The following is an analysis of several situations where the ink layer is blooming:
1. Unbalanced sizing degree of printing paper, and the ink layer on the printing surface caused by the poor smoothness of the paper
The process practice shows that the rough paper has a large ink absorption capacity. When printing paper with poor surface smoothness. The ink layer on the layout is prone to blooming. This is because the paper fibers interweave to create a certain gap, which is not well covered by the coating layer. In this way, there is poor contact between the paper surface and the ink layer on the surface of the printing plate during imprinting. In this case, if it is considered that the ink supply on the plate is insufficient and the amount of ink is increased blindly, the printing product will inevitably become sticky. Failure is undesirable. Instead, the printing pressure should be increased appropriately. Make the paper with poor smoothness and the ink layer on the plate surface achieve uniform and sufficient embossing contact conditions, so as to better eliminate the flowering phenomenon of the ink layer on the printing plate surface, and ensure that the printing ink layer is uniform and uniform.
2. The bottom of the printing plate is not solid enough, and the printing ink layer is weak due to the weak printing pressure.
As far as the printing process of relief printing plate is concerned, what kind of underlay sticky plate is used has a great influence on the transfer of the printing ink layer. Experiments and process practices clearly show that the traditional backward plywood used as a plate support has not only many disadvantages (such as low printing durability of printing plates, inaccurate overprinting, etc.), but also easy to produce poor ink layer transfer, causing plate layout Uneven or insufficient ink layer occurs. This is mainly because the wooden bottom tray itself is not strong enough, and the possibility of compressive deformation is large, resulting in unstable printing pressure, and the ink layer on the plate surface cannot be uniformly transferred to the printed sheet. This situation is often easily mistaken for insufficient ink supply. On the other hand, due to the poor flatness of the wooden bottom support, it cannot meet the normal ink receiving and transferring of the layout. If a multi-layer plywood is used as a backing, the thickness of the ink layer of the entire layout is often very different when printing a solid proof. Some of the layouts have obvious ink colors, and some of the inks look slightly pale at first, giving people ink Not enough illusion of uneven distribution of ink. After increasing the amount of ink supply, the visual effect of the lighter part of the layout is better, but it is also easy to cause sticky products, and it will cause undesirable defects such as overprinting, which is undesirable. The best way is to use the metal plate tray with good flatness and firmness for printing larger area plates, such as those with a size of more than 16 knots, in addition to carefully controlling the operation technology of the pad version. Phenomenon of ink color on the layout.
3. The rubber roller is hard or the position of the ink roller is poorly adjusted.
Color printing is usually a multi-color overprint product with a large layout and a large amount of ink absorption. However, large-format printing requires an even and moderate ink coating. If the rubber roller is hard, uniform ink transfer and ink distribution cannot be achieved because of the glue. When the roller is hard, its viscosity is weak, which is not conducive to ink transfer. On the other hand, the ink transfer roller, ink leveling roller and inking roller, respectively, can not be well joined with the ink fountain iron roller, ink fountain roller and printing plate, which is also the reason for the color of the printing plate. In this regard, careful analysis and inspection should be carried out one by one, and if there is a gap in poor adjustment, it should be readjusted to eliminate the gap. Repair measures should be taken for the gap caused by the wear of the shaft head and shaft hole. In this way, it is possible to better avoid the phenomenon of product page blooming caused by uneven ink transfer and ink distribution, and ensure the printing quality.
4. The anti-sticking agent in the ink is not stirred evenly, which causes the weak ink affinity of the printing plate, and the ink layer of the printing plate is bloomed due to poor ink transmission.
In printing plate products, after adding anti-sticking agent to the ink, it can play a certain anti-sticking effect. If the amount of anti-sticking agent is too much, such as more than 4% or the anti-sticking agent is not loosely mixed in the ink and cannot evenly penetrate into the ink, then the coarse particle of the anti-sticking agent will pass to the plate surface and affect the Ink-friendly, after printing, the ink color of the product surface will appear flower-like. Therefore, it is necessary to close the ink adjustment technology. When using the anti-sticking agent, you should first use an appropriate amount of varnish or ink, adjust the anti-sticking agent to be added to the ink, and then add it to the ink. In this way, the flowable release agent is easier to penetrate into the ink, which not only can receive a better release effect, but also can avoid the occurrence of blooming in the ink layer of the printed product.
In summary, as long as we are usually good at summing up experience in process practice, and accurately understand the various reasons that cause the product ink layer to bloom, we can better avoid blindness in process operation, thereby ensuring printing efficiency and Product quality improvement.
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