do you know? When the stability of printing quality is seriously damaged, the fundamental reason is not the performance of the ink itself, nor the accuracy of the anilox roller, but because the anilox roller is blocked by the dry ink during the working process. Caused by. This article details the causes and cleaning methods of anilox roll blockage.
In production, ink clogging of ink cavities is indeed a headache, and it is only possible to clearly observe the clogging of ink cavities with a 10x or 20x magnifying glass.
1. Three major reasons can cause the anilox roller to block
The dry ink at the bottom of the ink cavity, especially the water-based ink, is more difficult to dissolve in the new ink after drying, unless the dissolution time is very long. A clogging failure will reduce the effective ink delivery of ink cavities. Generally speaking, there are three basic reasons for the blockage of the anilox roller:
a. When replacing the printed parts, the anilox roller is not cleaned thoroughly;
b. Long-term shutdown without cleaning the anilox roller;
c. Ink drying performance is too fast.
"Workers must sharpen their tools first if they want to do their best." Therefore, in order to maintain the accurate transfer of ink volume, the anilox roller must be cleaned reasonably.
2. Five cleaning methods, essential
a. Chemical solvent scrubbing method
Spray the chemical solvent on the surface of the anilox roller, select the appropriate fine brush according to the material of the anilox roller (ceramic anilox roller with stainless steel brush, metal anilox roller with copper wire brush), and brush repeatedly. This method is only suitable for cleaning the anilox roller of coarse wire. The advantage is low cost, easy cleaning, and no pollution to the environment; the disadvantage is that it can not be deeply brushed into the ink hole, so the cleaning is not thorough. It is difficult to clean the dirt and ink deposits on the bottom of the ink hole. Therefore, the ink cavity volume cannot be restored.
b. Chemical solvent immersion method
Infiltrate all or part of the anilox roller into the tank with high pH and strong corrosive cleaning agent, let the solvent dissolve and soften the dry ink, and finally wash off the corrosive cleaning solution and the fully corroded and softened ink with clean water. It is more effective, but for long-term use, corrosive solvents will penetrate the protective layer and corrode the steel body, which is not conducive to environmental protection.
c. Ultrasonic cleaning method
Immerse the anilox roller in the tank of an ultrasonic cleaning system filled with chemical cleaning solution. The frequency converter in the tank sends high-frequency sound waves. The solution vibrates and generates bubbles. The dry ink, resin, and coating material in the ink cavity vibrate in the solution. Under the combined action of the inward explosion force generated by the directional explosion surface of the bubble, it will flow away from the ink hole and with the cleaning liquid. The cleaning time depends on the size of the rollers and the ink is clogged. It usually takes 0.5-24h. During this time, the anilox roller will be exposed to high-frequency ultrasonic vibration for a long time, which will damage the ceramic layer, and will cause certain damage to the ink layer of the anilox roller and the ink cavity. In addition, this method occupies a large area, high investment cost, and complicated process. Although it has a certain cleaning effect, whether this method is perfect or not needs to be tested in practice.
d. Low pressure spray washing method
Using sodium bicarbonate, baking soda, as a cleaning powder, spray the anilox roller under low pressure to thoroughly clean the dry ink, resin, coating material, etc. remaining in the ink cavity, but pay attention to the jet pressure should not be too high, otherwise It is possible to separate the ceramic soil layer from the anilox roller body, and the general pressure should not exceed 0.1 MPa. Because sodium dicarbonate and sodium bicarbonate are a kind of softening cleaning medium, they are easily soluble, non-toxic and harmless, and meet the current global environmental protection requirements. Practice has proved that this method has a good cleaning effect, which can restore the ink cavity volume, and can be directly cleaned on site, including ink fountain, grease, and ink stains. Although this method has only developed in recent years, it has great potential and is worth promoting.
e. Plastic beads spray cleaning method
The principle is similar to the low-pressure spray washing method, but the cleaning powder uses fine plastic beads. This cleaning method can increase the cleaning speed of the anilox roller by 30%, and can improve the quality of the printing while extending the life of the anilox roller. This method consumes less plastic beads, and there is no discharge of harmful substances and precipitation of chemicals during the cleaning process, which is beneficial to environmental protection, high efficiency and safety.
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