2021-08-18
How do flexible packaging materials companies deal with the high temperature and high humidity climate in summer?
The summer high temperature and humidity environment has a more obvious impact on the gravure production of flexible packaging materials. Because the current flexible packaging material companies still use solvent-based gravure printing inks, high temperature can easily promote the rapid volatilization of organic solvents in the ink, and high humidity is easy to change The viscosity of the ink affects the gravure quality of flexible packaging materials. At the moment of the high temperature of two volts, understanding the impact of high temperature and high humidity on the gravure production of flexible packaging materials, and how to make countermeasures to reduce unnecessary quality losses, has become the most concerned issue of flexible packaging materials companies.
1. Shallow net anti-white dots and small text blockage phenomenon
When the ambient temperature rises, the volatilization speed of the organic solvent in the gravure printing ink will increase, and the printed products will show the phenomenon of shallow net white spots and small text blocking.
Countermeasures:
At this time, the slow-drying solvent should be added in time, but the addition amount should be determined according to the actual situation, otherwise excessive addition will cause problems such as excessive solvent residue and anti-sticking of the ink.
2. The phenomenon of false ink drying
The ink is falsely dry, that is, the ink layer does not dry on the surface and inside. This phenomenon can easily lead to excessive solvent residues, poor ink layer adhesion, and ink anti-sticking after winding.
Countermeasures:
Appropriately reduce the viscosity of the ink; reasonably control the printing speed; adjust the matching degree between the air volume and the air temperature; improve the drying capacity; maintain a constant temperature and humidity.
3. Excessive solvent residue
When the environmental humidity increases, the ink drying speed will slow down. Under normal circumstances, if the ambient temperature is 20°C, when the humidity rises from 65% to 75%, the difference between the front and back drying speed of the ink can be 1 to 2 times. In addition, most flexible packaging material companies will use a large amount of slow-drying solvents in summer gravure production, especially for low-speed gravure printing machines. To ensure the printing effect of the printed products, especially the shallow mesh area, a large amount of butyl ester must be added. However, the drying efficiency of low-speed gravure printing machines is low, which will lead to excessive solvent residues.
Countermeasures:
For high-speed gravure printing machines, due to the faster speed, there is no need to add too much slow-drying solvent to adjust the ink drying speed. At this time, the ink viscosity is low, and the ink layer after transfer is thinner. The drying temperature can achieve a good drying effect. In view of the high-temperature and high-humidity environment that may cause excessive solvent residues in printed products, gravure printing companies of flexible packaging materials should use gas chromatographs to do real-time monitoring in order to prevent problems before they occur.
4. Ink anti-sticking phenomenon
During the storage and handling of printed products, if the ambient temperature is too high or the ventilation is not good, it is easy to cause the ink anti-sticking phenomenon, especially for the printed products with high tension in individual parts after winding (such as the position where the printed patterns are relatively concentrated) . In addition, factors such as high solvent residues, false ink drying, and poor ink layer adhesion caused by high-temperature and high-humidity environments will also aggravate the ink anti-sticking phenomenon after rewinding.
5. Influence on the stability of ink plate ink
At present, since closed or semi-closed squeegee systems have not been promoted and applied in gravure production, most flexible packaging material companies still use open ink trays, that is, the ink in the ink tray is directly exposed to the air. However, in a high-temperature and high-humidity environment, the stability of the ink in the open ink tray will gradually deteriorate: high temperature can easily lead to "solvent imbalance", leading to a series of printing failures; high humidity can easily increase the ink viscosity and cause blockage.
Countermeasures:
Aiming at the phenomenon of "solvent imbalance", gas chromatograph can be used to analyze the actual ratio of solvent components in the ink plate ink to avoid improper design of the solvent volatilization gradient, which causes the ink solvent ratio to change.
6. Impact on printing quality of nylon film
Nylon film is a product that is very easy to absorb moisture. Changes in size after moisture absorption can easily lead to inaccurate overprinting during the printing process. The slower the printing speed, the more inaccurate the overprinting. In the bag making process, the front and back patterns are prone to misalignment. Inability to align and other problems, in addition, the water film accumulated on the surface of the nylon film can also cause insufficient composite strength and blistering.
Countermeasures:
Put the nylon film in the curing room to dry for 2 to 3 hours before use. Do not open the package too early; when printing, the first color group is not printed on the plate roller, and pre-drying is required; the nylon film should be used up as much as possible at a time; The nylon film should be moisture-proof and dry; the workshop should maintain a reasonable and constant temperature and humidity.
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