Pressure, paste, vignette and other processing

First, the pressure problem

Printing pressure has a great influence on print quality. Maintaining an even and constant printing pressure in the effective printing area can not only make the prints uniform in ink color but also have a small color difference, and can also make the print size stable. Flat presses can achieve maximum printing pressure. However, due to the problem of flatness of the printing plate produced by the manufacturing precision and the thickness of the adhesive substrate cannot be completely uniform, the pressure is uneven and the printing quality is affected. One way to solve the pressure unevenness is to make a pad, where the pressure is low, put the bottom of the worktable where it is cushioned; one is to properly reduce the hardness of the flexible plate. However, reducing the hardness of the flexographic plate is limited. If the flexural hardness is too low, the geometrical dimensions of the image will expand outwards, making the small font easily blurred. When printing large areas, the problem of printing pressure is not easy to solve. For this, we use the method used in bronzing, that is, padding on the workbench with a layer of 175 lines and a silicone plate with a hardness of 90°. This can solve the problems of exhaust and partial pressure.

Second, paste problem

Small texts such as fonts under No. 8 Since the fine line spacing is too small, ink drying often occurs on the top, resulting in no inter-textured adhesion. This is mainly due to ink drying too quickly. Our company is now using a resin offset printing ink produced by Shenzhen Ink Co., Ltd. It has a higher viscosity and a higher temperature, and the ink dries faster. The printed product is a very fine adhesive print. The phenomenon of dry printing is relatively high. . If this happens, first find the problem from the flexible resin version. It is generally required that the resin version has a slippery feel on the bottom of the font and should not be sticky. However, due to underexposure, the bottom of the font is soft and sticky. The ink is more likely to stick to the ink and the ink accumulates and dries inside the thin thread. If you do not use it, you will waste the media. At this time, it can be treated with a resin plate post-treatment liquid containing sodium hypochlorite and hydrochloric acid, which can harden the character and eliminate stickiness. The most fundamental way is to find out the exact exposure time and produce a resin version that meets the standards. The suggestion of a particularly elaborate font is to use a copper-zinc plate. Copper-zinc plates are not easy to dry, but the fonts are hard and it is easy to print clear strokes. In the operating environment, pay attention to reduce the air to the flow, if it does not work, you can add appropriate slow drying agent in the ink to reduce the drying speed. Relatively suitable increase in printing speed can prevent the ink from drying excessively. 

Third, the vignette problem

Sometimes there will be cloud-like shadows on adhesive products, which are mainly caused by uneven ink distribution. The leveling roller is a chrome-plated iron roller with a diameter of 150mm that can be axially ganged. Its function is to receive ink from the ink fountain roller and the transfer roller and evenly mix the ink and transfer it. To the ink roller, it is easy to form vignetting when the ink roller loses the ink string effect. In addition, the ink roller is made of soft nitrile rubber vulcanized, if you do not pay attention to maintenance, so that the ink effect is reduced, it can also cause vignetting, to solve the vignette is to solve uneven ink uniformity problem, can be appropriately increased to the amount of ink.

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