The phenomenon of "blooming" refers to the field part of a printed matter that should have been continuous, but due to the irregular transfer of ink in the plate pattern, there are thin lines in the field part, so the actual part can not be printed smoothly, and the field part after printing is not smooth and smooth, which is in the shape of water grain orange peel. In addition, the level of graphics and text part of the virtual. The causes and solutions are as follows:
1. Moisture effect. There are two sources of water: one is that the diluent contains water, especially toluene is easy to contain a certain amount of water. The second is condensation water, because the solvent volatilizes too fast (at this time, the ink surface is easy to crust), so that the temperature of the ink surface is reduced due to the absorption of heat. The moisture air with high humidity and high temperature will condense on the ink surface and form a layer of condensation water. If you observe carefully, you will find that there will be many small water droplets on the surface of the ink skin, and these water will also enter the inside of the ink. When printing, with the accumulation of water in the ink, the water will peel off the resin in the ink and emulsify the resin. The ink becomes a water in oil (w / O) structure. The pigment particles wrapped by the resin are exposed by water replacement, and gradually agglomerate together and thicken (blocking the mesh) in the collision. Therefore, macroscopic observation of the ink will find that the ink becomes sticky, thickened, rough and not smooth; at the bottom of the ink trough There is a large amount of precipitation (white ink is the most obvious, because titanium dioxide has the strongest hydrophilicity); there is also a thin layer of mist on the non graphic part of the printing plate, and the scraping is not clean (if the pressure of the scraper is increased, the printing plate will be damaged); at the two ends of the printing plate of some printing machines, the resin of the gelatinous substance gradually transits to the imprint roller, and the thicker the accumulation is, the more the space between the imprint roller and the plate is increased Gap, so that the register is not accurate, and damage the imprint roller. Printing ink transfer is less and less, more and more shallow, not coloring. Due to the effect of water on the ink, the ink becomes an uneven body, so the printed matter appears "flower" and leakage after printing. The water content of the diluent can be preliminarily detected with "water testing agent", and the diluent with excessive water content cannot be used. In addition, the temperature and humidity of printing workshop should also be controlled within the standard range.
2. The real solvent volatilizes. In the printing process, too fast evaporation of the true solvent in the ink will lead to the following two problems: one is resin precipitation. This problem for some types of ink, such as polyurethane type ink is very obvious. Resin precipitation leads to a series of changes, such as viscosity, thickening and coarsening of the ink, resulting in printing defects such as "blooming" and false printing, which is similar to the effect of moisture on ink. The second is the ink's re solubility. In normal printing, only about 2 / 3 of the ink transferred to the substrate and 1 / 3 of the ink remained in the mesh. Due to solvent volatilization, the residual ink in the mesh becomes dry and solid. At this time, if the back of the ink on the previous dry ink poor solubility, then the network of dry solid ink will be more and more (i.e., buried version), and the second can transfer to the substrate ink less and less, printing ink can not completely cover and sink, there is a "flower" phenomenon. For this type of ink, in the printing process should be a separate part of the true solvent, and adjust the proportion of each solvent in the diluent.

3. Improper printing operation. The balance of printing speed, printing pressure, scraper pressure and angle, ink viscosity, ink concentration and ink dryness should be well coordinated. If the faster the printing speed is, the faster the ink dryness and the lower the ink viscosity, the higher the ink concentration is required; vice versa. If the ink viscosity is high, the printing speed is fast, or the ink viscosity is low, and the printing speed is slow, these two situations are easy to cause printing "blooming". When the printing speed is 100-120 M / min, the viscosity should be controlled between 17-18 seconds for color ink and 14-16 seconds for white ink (chaen No.3 cup); at 50-80 M / min, color ink is 20-22 seconds, and white ink is 18-20 seconds. These cases should also be combined with the grade of ink and the printing plate of the screen. If the printing speed is fast, the viscosity must be low, if the ink concentration is also too low, the print is bound to leak. Similarly, when the printing speed is slow and dry, it is easy to cause paste; otherwise, it is easy to cause anti stick or solvent residue.

4. The ink and plate are not matched well. If the printing requirements are high and the printing speed is fast, high-grade ink should be selected, which requires high ink color concentration, low viscosity, and good transfer effect. When the ink is selected, there are certain requirements for the screen width of the plate according to the product requirements. As the saying goes, it is difficult to use the ink performance in printing when the printing plate is not good, which does not make up for the shortcomings of the plate. In general, the number of lines of the white version is 175 lines and the depth of 35 μ is 35 μ. Some manufacturers may require to deepen the depth of the version, because this version is a leading product, with large batch and long durability requirements. However, when the plate is deepened, the dot will be increased, the number of lines will be reduced, and the screen width will be increased. As a result, it is very easy to cause "hairiness" phenomenon when printing.
5. Ink is poor. Mainly in the following two aspects: one is the ink drying too fast, the ink is easy to dry in the pit, so that small characters or patterns can not be printed, this phenomenon is also known as paste version. At this time, slow drying solvent should be used to adjust the drying rate. Second, ink thixotropy, thick, poor leveling. Ink transferred to the substrate after diffusion, printed products appear "hairy". This type of ink should be replaced.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
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