Analysis and solution of common problems in flexographic printing
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In recent years, the flexographic printing method has developed rapidly in China, especially in the aspect of product packaging, and more and more flexible printing methods have been adopted. However, in the actual production process, due to the influence of printing materials, ink properties, printing machinery, working environment and other factors, some printing failures often occur, affecting the smooth progress of production and the quality of the final printed matter.
Fault one
Paste
Reasons:
1. The printing plate is too shallow;
2. The printing pressure is too large;
3. The ink supply is too much;
4. The ink viscosity is too high;
5. The ink dries too fast.
Solution:
1. Re-plate, and appropriately reduce the back exposure time, increase the depth of the plate embossing;
2. Appropriately reduce the printing pressure;
3. Reduce the ink supply amount;
4.Reduce the viscosity of the ink;
5. Reduce the hot air drying. The strength, appropriate to slow down the speed, or add the right amount of slow-drying agent.
Fault two
Sticky
Reasons:
1. The ink is not dry enough;
2. The viscosity of the ink is too high;
3. The tension of the rewinding is too large.
Solution:
1. Increase the drying temperature, or add a proper amount of solvent to evaporate quickly; 2. Reduce the viscosity of the ink;
3. Reduce the rewinding tension.
Fault three
Imprinting is not allowed
Reasons:
1. Improper tension;
2. Improper arrangement of printing color group;
3. Mechanical vibration or mechanical deviation;
4. Uneven printing material;
5. Improper temperature and humidity in the printing workshop, too high drying chamber temperature, especially paper The film shrinks severely.
Solution:
1. Adjust the unwinding and winding tension;
2. Re-adjust the printing color sequence, arrange the strict color of the registration in the adjacent color group next to the printing, in case of deviation, if necessary, appropriately Place one or two layers of transparent tape under the double-sided tape;
3. Inspect the machine and adjust the corresponding machine parts;
4. Adjust the tension or replace the printing material;
5. Reduce the drying temperature and try to keep the temperature constant in the workshop. Constant humidity, if conditions permit, install air conditioners in the workshop.
Fault four
Stack color effect is not good
Reasons:
1. The previous color ink is not dry enough;
2. The viscosity of the latter color ink is too high.
Solution:
1. Add an appropriate amount of solvent that evaporates quickly to increase the drying speed of the ink of the previous color;
2. Reduce the viscosity of the ink after the color.
Fault five
Ink blistering
Cause: Printing speed is too fast, and no defoamer or defoamer is used.
Solution: Add an appropriate amount of defoamer, or reduce the printing speed appropriately.