The printing plate endurance is directly related to the economic benefits of production, and it is also an important condition to reduce production costs, increase output, and ensure printing quality. The influence factors of gravure ink and environment on the printing resistance of printing plate cylinder mainly include the viscosity and drying speed of ink, impurities such as hard sand particles, dust, ink erosion, and chemical factors. The following is an analysis of these factors.

1.Viscosity and drying speed of ink

In order to scrape off the excess ink from the surface of the plate cylinder, the doctor blade must penetrate the ink film, so when the ink viscosity is large, a larger blade pressure is required. Therefore, it is necessary to reduce the viscosity of the ink as much as possible in order to reduce the pressure of the doctor blade.

In addition, the ink is over-dried, and the friction between the plate cylinder and the scraper is relatively increased, which also has a certain impact on the life of the plate cylinder. In addition, when the environment is wet too much, the dispersion of the ink becomes poor, and the printing plate cylinder is not easily scraped. Therefore, the pressure of the blade must be increased accordingly, and the friction of the blade to the printing plate cylinder is increased accordingly.

2.Effects of impurities such as hard sand and dust

If there are hard particles in the ink, the plate cylinder will be easily scratched by the hard particles when scraping the ink. The lighter will affect the printing quality, and the heavy one will cause the platen cylinder to be scrapped. In addition, the impurities on the surface of the substrate are easily mixed into the ink, which accumulates too much over time, and easily damages the plate cylinder. Therefore, it is often necessary to keep the substrate and ink clean and short. In order to remove foreign matter, the ink in the ink tank can be filtered regularly or a wire mesh can be inserted into the ink recirculation system for continuous filtering. Dust in the environment, whether it falls into the ink or is adsorbed on the impression cylinder, will directly damage the scraper and the plate.

Impurities, coarse particles, and foreign matter in the ink are mainly caused by the following factors:

(1) Foreign particles mixed in the ink or the additives in the ink will precipitate with temperature change and the pigments will agglomerate to produce coarse particles.

(2) Foreign matter in the department is brought in by the film. When the dust absorbed by the film due to static electricity and the additives in the film precipitate into the ink, foreign matter is formed. Especially when the workshop is too dry, the film can easily attract dust due to static electricity, which will affect the life of the plate cylinder.

(3) When a pigment with high hardness is used, knife lines may be caused even by kneading. For example, pigments used in red and blue inks are difficult to grind, and knife lines are relatively easy to occur.

(4) The dust or air duct sucked into the outside air by the drying system will not be cleaned for a long time.

3.Invasiveness of ink

Some inks, such as black ink, are erosive to the plate cylinder, so they should be cleaned in time after use.

4.Chemical factors

A certain amount of active agent is added in the production process of the ink. If the activity of the ink or the printing plate cylinder is too high, the active substance will adhere to the printing plate cylinder more firmly during the printing process. This has to increase the blade pressure, which in turn affects the life of the plate cylinder. At this time, the plate cylinder can be cleaned, and the active substance that has adhered to the plate cylinder can be removed, and then a special surface activity reducing agent is added to the ink, and a significant effect will be achieved. If a surface active moderator is added before printing, it can play a preventive role.

 Kunshan Printing