Reasons and Countermeasures for ink film dryness o

Reasons and Countermeasures for dry ink film of sheet fed offset printing (IV)

IV. too thick ink film will reduce the contact between the middle part of the ink layer and the air, especially after the formation of film on the surface of the ink layer, it will hinder the entry of oxygen in the air, and the middle part will dry slowly

therefore, we should strictly prevent the following situations in printing:

(I) the imprint is not strong due to other reasons, and the thickness of the imprint is wrongly increased

(II) the ink color is light due to excessive moisture in the layout, but the ink color is improved by increasing the ink supply

(III) overemphasize the bright and thick impression. Improperly increase the ink supply

(IV) it is required that the contact surface with the spindle should not be less than 75%. The coloring force of the printing ink is too low, but the thickness of the ink layer should be increased to remedy it

(when mixing light spot color ink, pay attention to the slightly higher saturation of the color, so that the ink film on the substrate can be thinner during printing, which is conducive to drying. In addition, the less ink types are used when mixing ink, the less emulsifying the ink is during printing, which is also conducive to drying)

the thickness of the ink layer on the surface of the substrate and the distribution of graphics and text

due to the uniform consumption of wetting liquid, the emulsification of ink is the same for the pictures and texts distributed evenly in a large area, but the emulsification of ink on both sides is more serious than that in the middle due to the direct contact with excess water in the blank part. Similarly, when the area of graphics and texts on the lithography is smaller, especially when the small area of solid land or small area of dark tone, the emulsification value of the ink will also be large, which is more likely to cause the problem of dry ink layer. For this, in addition to increasing the amount of desiccant, we should strictly control the water volume of the layout

some solutions to the problem of dry printing in printing

in fact, in modern multi-color offset printing, even if good printing conditions and reasonable processes are adopted, it is difficult to achieve that the ink can be dried in time during the printing process or after the printing is completed. By vigorously implementing the innovation driven development strategy, the ink can be dried in time, Therefore, we often use the following three methods in production to accelerate the drying of the ink film or prevent the back of the printed matter from rubbing dirty

powder spraying: powder spraying is a commonly used method in printing. It is an effective means for the back rubbing caused by the slow development and drying of ink film motorcycles, pens and pipes. When the ink layer is thick, the amount of powder spraying can be appropriately increased, especially when there are small areas of dark tones or field ink blocks on the surface of the substrate, we should pay more attention to appropriately increasing the amount of powder spraying. Generally, the amount of powder spraying should be as small as possible in the effective range, otherwise it will affect the ink color of the printed matter, especially on the products required for bronzing and film coating, we should pay more attention to controlling the amount of powder spraying

drying rack: the paper receiving part of the printing machine adopts the method of layered paper receiving, that is, every 5 ~ 20 cm (the thickness of the separated paper layer can be adjusted according to the density of the substrate and the thickness of the surface ink layer. When the density of the substrate is large and the thickness of the ink layer is large, the height of the separated layer should be appropriately reduced) to prevent the paper from being damaged by the weight of the paper, or the back felt is dirty

shake and dry: printing materials with poor surface absorption and thick ink film generally dry slowly. Due to the less contact between the stacking of papers and oxygen in the air, the oxidation drying process is hindered. Therefore, gently shake the paper at intervals to make it breathable and increase the contact between ink and air, which can effectively speed up the drying of ink

finally, let's review the key to control the slow drying of ink film on the surface of printing materials mentioned in this paper, as well as some process methods for printing materials with slow drying ink:

1 Select the appropriate ink, 2 Use additives and auxiliary agents as little as possible in the printing process, 3 Use a proper amount of dry oil, 4 During printing, control the water volume of the page and the pH value of the fountain solution, 5 It is important to ensure constant temperature and humidity in the environment, 6 Control the ink film thickness of pictures and texts, 7 Powder spraying, drying rack, shaking and drying

so far, we have analyzed some reasons for the slow drying of ink film on printed matter and some solutions when the ink dries slowly, hoping to help you

information source: Bisheng

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