In modern printing, whether it is flexographic printing or gravure printing, rotary printing is the main method; in many areas of offset printing, rotary printing is also the most important method. However, the roll printing materials used in rotary printing can easily cause printing difficulties due to the adsorption of impurities such as dust, and cause the quality of printed materials to decrease and increase the rate of rejects.
During the production or stacking process of the roll paper or roll plastic film, a lot of electrostatic charges can be accumulated due to friction, resulting in higher or even very high electrostatic voltage. It will adsorb the dust, packaging materials, fibers on clothing, hair, micro-organisms, residual ink particles, etc. to the surface of the printing material, which will cause difficulties in the production of printing, compounding, and glazing processes.
After the dust and other impurities come into contact with the plate cylinder, they will be transferred to the plate cylinder and adhere to the plate cylinder, which will damage the ink transfer performance of the plate. In order to remove the dust from the plate cylinder, the operator had to stop and clean it. If there are many impurities such as dust attached to the printing material, it usually needs to be washed once in less than half an hour. Cleaning the plate cylinder will not only prolong the printing production time, resulting in loss of production efficiency, but also every time you restart printing after cleaning, there will be a process of adaptation, inevitably the loss of a part of the printing material, accumulated over time. For a considerable amount.
How to properly deal with such problems, Anping suggested that the following aspects should be given sufficient attention.
1. Dust removal of paper and cardboard:
Impurities such as dust may come from papermaking, slitting, die cutting, grooving, envelope window opening processes, and napkin production lines, so they must be completely removed, otherwise it will affect the quality of printed products and reduce production efficiency.
2. Static elimination of plastic film and metal foil:
Both plastic films and metal foils are more prone to static electricity. Therefore, before printing, be sure to do dust removal and cleaning to reduce the additional auxiliary time such as shutdown and cleaning in printing production as much as possible.
3. Cleaning of food and drug packaging bags before forming:
Food and pharmaceutical packaging bags must be heat-sealed into packaging bags. Thermoformed packaging materials must be absolutely clean before molding. The cleanliness of materials used in vacuum packaging must meet quality standards.
4. Dust removal before coating:
Regardless of the glazing of paper, plastic film or metal foil, the dust removal treatment should be performed first. Dust and other impurities adhere to the printing material, which will greatly affect the glazing quality.
Since the dust and other impurities are attached to the surface of the printing material by electrostatic adsorption, the static eliminator must be installed to eliminate static electricity before the dust can be completely removed to meet the processing requirements of printing.
1. Working principle of static eliminator:
The high-voltage electric field is used to ionize the air into positive and negative air ions. This positively and negatively charged air ions are used to neutralize the electrostatic charge on the surface of the printing material. This eliminates static electricity and does not attract dust.
2. Equipment required for static eliminator: one power supply and one static elimination device.
3. How to choose static elimination equipment: Static elimination equipment includes ion fans, ion rods, ion wind snakes, ion wind nozzles, ion wind guns, etc. The printing industry generally chooses ion rods, of course, there are other series of products.
4. Size of static eliminator: It can be customized according to customer's requirements, and the appropriate size can also be selected on site survey.
5. Installation location: The installation location is different in different scenarios, please refer to the following application scenarios:
6. Static eliminator maintenance: The static eliminator is affected by environmental factors in the printing area. If the static eliminator is in working state for a long time, it will cause different degrees of adsorption of debris on the needle tip, resulting in poor static elimination effect. Regular cleaning and maintenance. That is: use electrostatic brush, dust-free cloth dipped in absolute alcohol to gently remove the carbon deposits on the discharge electrode, rod core and metal discharge bar, and its performance will be significantly improved.