The amount of ink transferred to the plate when the anilox roll is rotated is actually a variable and is affected by many factors. Under normal conditions, the amount of ink filled in the ink pocket can be transferred to the printing plate in the range of approximately 70-80%. Even if the stability and dispersion uniformity of the ink itself meets the quality requirements, and the anilox roll is manufactured with high precision, the amount of ink transferred to the plate is also very limited. When the stability of the quality of the printed product is seriously damaged, the root cause is not the performance of the ink itself, nor the accuracy of the anilox roll, but the clogging of the ink which is dried by the anilox roller during the working process. Caused. The dry ink at the bottom of the ink hole, especially the water-based ink, is more difficult to dissolve in the new ink after drying, unless the dissolution time is long. Blocking the fault will reduce the effective amount of ink that is passed through the ink pocket.
There are three basic reasons for the blockage: a. When the print is replaced, the anilox roller is not thoroughly cleaned; b, the machine is stopped for a long time, and the anilox roller is not cleaned; c, the ink drying performance is too fast. "If you want to do something good, you must first sharpen your tools." Therefore, in order to maintain accurate delivery of ink, the anilox roller must be properly cleaned.
Currently, there are five cleaning methods:
Chemical solvent scrubbing
A chemical solvent is sprayed on the surface of the anilox roll, and a suitable fine brush (a stainless steel brush for a ceramic anilox roll, a copper wire brush for a metal anilox roll) is used according to the anilox roll material, and the brush is repeatedly brushed. This method is only suitable for cleaning the anilox rolls of the thick wire. The utility model has the advantages of low cost, convenient cleaning and no pollution to the environment; the disadvantage is that the brush cannot be deeply penetrated into the ink hole, so the cleaning is not thorough. It is difficult to clean the dirt and ink on the bottom of the ink hole. Therefore, the ink pocket volume cannot be restored.
Chemical solvent immersion
Intrinsically or completely infiltrating the anilox roller into a high-corrosion cleaning agent tank, allowing the solvent to dissolve and soften the dried ink, and finally washing away the corrosive cleaning solution and the fully corroded and softened ink with water. It is more effective, but for long-term use, corrosive solvents will penetrate the protective layer and corrode the steel body, which is also not conducive to environmental protection.
The anilox roller is immersed in a tank of an ultrasonic cleaning system filled with a chemical cleaning solution, and the frequency conversion device in the tank transmits a high-frequency sound wave, which is a solution vibration and generates bubbles, and the dry ink, resin, and coating material in the ink hole vibrate in the solution. Under the combined action of the inward explosion force generated by the bubble-oriented explosion surface, it flows away from the cleaning liquid at one place. The cleaning time depends on the size of the roller, and it usually takes 0.5-24h. During this time, the anilox roller will be damaged by high-frequency ultrasonic vibration for a long time, which will damage the ceramic layer, which will cause certain damage to the ink layer of the anilox roller. In addition, this method has a large area, high investment cost, and complicated process. Although there is a certain cleaning effect, whether this method is perfect or not requires actual testing.
Low pressure spray method
Use sodium dicarbonate, baking soda, as cleaning powder, spray the anilox roller at low pressure, thoroughly clean the dry ink, resin, coating material, etc. remaining in the ink hole, but pay attention to the injection pressure should not be too high, otherwise It is possible to detach the ceramic soil layer from the anilox roll body, and the general pressure should not exceed 0.1 MPa. Because sodium dicarbonate and sodium bicarbonate are softening cleaning media, they are easy to dissolve, non-toxic and harmless, and meet the global environmental requirements. Practice has proved that: this method has a good cleaning effect, can restore the volume of the ink hole, and can be directly cleaned on the spot, including ink fountain, grease, ink and the like. Although this method has only developed in recent years, it has great potential and is worth promoting.
Plastic fine bead spray cleaning
The principle is similar to the low pressure spray method, but the cleaning powder is made of plastic beads. This cleaning method can increase the cleaning speed of the anilox roller by 30%, and can improve the quality of the printed product while prolonging the service life of the anilox roll. In this way, the consumption of plastic beads is small, and the cleaning process does not discharge any harmful substances and precipitates chemicals, which is environmentally friendly, efficient and safe.
ADDRESS:Qianbu Industrial Zone, Xincheng Street, Ruian City, Wenzhou, China
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