Troubleshooting of the most popular gravure pearle

Example analysis of troubleshooting of gravure pearlescent ink printing

gravure pearlescent ink is composed of pearlescent powder, gravure ink connecting material, organic solvent and thorn aid. Person in charge: we will further implement the quality supervision and testing function. With the rapid development of the printing industry, especially in the printing of cigarette labels and wine labels, pearlescent ink is more and more favored by packaging JH households for its unique visual effect. Pearlescent ink often has some unexpected printing problems when it is used on a gravure press. Here are two examples:

a printing factory in the South debugged pearlescent ink. The printing equipment is a flat gravure press made in Shanghai, and the printing speed is 6000 sheets/hour. The ink connecting material is nitrocellulose and a small amount of polyketone resin. The dilution used is the mixed solvent of ethyl acetate and isopropanol. During the debugging process, pearlescent ink printing is always poor, Leveling error and other phenomena. After careful observation with a 25X magnifying glass, it was found that the ink dried too fast. If we compare Huzhang gravure printing machine with rotary gravure printing machine, the actual linear speed formula of a normal 6000 sheet/hour machine is as follows: v = 6000x Ⅱ XD/60. If the plate diameter of the flat gravure press is 0.375 meters, the linearity is 118 meters. Obviously, the machine speed is very fast. Why does the ink dry fast? After demonstration, due to the flat catalyst revenue reduction of 28%, the gravure printing plate diameter is large, although the linear speed is very high, but the angular speed is very slow, most of the printing plates are exposed to the air, the ink has not been fully leveled, and it has dried in the printing plate hole, resulting in blocking. Add slow drying solvent, ethyl acetate, isopropanol, propylene glycol methyl ether, the ratio is 3:3:4, the ink viscosity is adjusted to 24 seconds (2 # chann cup), and the machine speed is 6000 pieces/hour, which can meet the customer's requirements

in batch printing, the ink film after printing is used for a touch, and the ink falls off in a large area, reducing the amount of slow drying solvent. The effect of pearlescent is not good, and blocking occurs again. Can it be the problem of paper? For another white card, the problem remains the same. Is there a problem with pearlescent ink? Pearlescent powder is flaky, which is difficult to form a flat and dense film. The ink dries too slowly, and a large number of connecting materials penetrate into the paper or solvent residues. If there is a need to replace the gasket, it will remain in the graphic and ink film of flexible packaging printing, resulting in the suspension of pearlescent powder on the surface and falling off. According to this idea, replace nitrocellulose with acrylic resin, reset the juice formula and try the machine again, and the problem is solved

due to the special nature of pearlescent ink, it is difficult for pearlescent ink to be completely miscible with flexible packaging substrate and gravure printing ink of ordinary paper. This situation occurred when printing pearlescent ink in Wuhan printing plant. Because pearlescent ink is mixed with a large number of ordinary inks, the surface of printing products is always uneven and dirty. At first, it was thought that the quality of pearlescent oil was poor, and changing another ink could not solve the problem. It is also suspected that there is a problem with the ink return. It is still not possible to put the ink inlet of the ink tank under the ink tank and install the return pipe on it. Lengthen the scraper and increase the miscible area between pearlescent ink and ordinary ink. Although the problem of dirt is solved, there are some faults such as unclean scraping and tailing. In order to increase the dispersion of pearlescent ink, installing an inking roller under the gravure plate roller can also eliminate the problem of dirt. However, the parallel lines on the inking roller are occasionally printed on the product, and the scrap rate is greatly increased. An inking roller is installed at the bottom of the ink tank of the flat gravure press to strengthen the dispersion of the pearlescent ink, but the inking roller is not fixed. With the high-speed operation of the printing plate, the buoyancy of the ink to the inking roller is also very unstable, so the contact pressure between the inking roller and the printing plate has been changing, and it can not be printed normally. The ink tank of the gravure press is closed and difficult to change. If you make an open ink tank, like a rotary gravure press, let the inking roller run with the printing plate in front of the printing plate, and then try printing several times. After the batch printing, the above problems no longer occur, and the printing is normal

(Wen/Liu Jiaju, qianbaoshan, Yang Huikai)

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