Some problems in the process of printing

Some problems in the process of printing and printing

the printing operator should conduct a matching test on the exposure and development before working every day to determine the exposure time, development time and developer concentration suitable for printing and proofing. Methods: first, ensure that the temperature and concentration of the developer meet the development requirements. Then take a small PS plate and put the print signal bar on it for exposure test. Before the test, we should consider the different service objects of printing, and the exposure time test should also be adjusted to varying degrees

a. beat the polypropylene modified sample to reduce the volatility of polypropylene: after the signal bar is exposed and developed, the gray scale of level 4 requires half a grade to be sun off, the small points of level 2 are sun up, the reduction of point 50 is basically accurate, the points of level 80 cannot be reduced, and the edges of points are clear and tidy

b. printing plate: after exposure and development, the 4-level gray scale of the signal bar is required to be polished off by 1.5, and the upper 2 points are required to be polished off. The 50 and 80 points sharing weal and woe are basically restored accurately, and the point edges are also required to be clear and tidy. The reason why the drying of printing plates and proofing plates are inconsistent is mainly to solve the difference in mechanical performance between proofing machines and printing machines, so as to ensure that the printing and proofing samples basically achieve the same effect in terms of tone, hue and saturation

greatly understand the performance indicators of the PS version and use the PS version correctly

when replacing a new PS version or using a PS version produced by the same manufacturer with different batch numbers, the photosensitive speed will be different due to different proportion of photosensitive solution, so the exposure time, development time and concentration of developing solution should be changed accordingly

when using the developer, in order to achieve the ideal effect of developing theater, it is best to use the developer matching with the PS version, because the alkali resistance of the PS version produced by different manufacturers is strong or weak. If the PS version with weak alkali resistance is developed with the strong alkaline developer, the light sensitive layer without photodegradation will be seriously affected, and the dot will become smaller and the image tone will be lost after development

when the developer concentration is too high, it is not only the friction is relatively large, the service life is short, but also the photosensitive layer is corroded, and the oxide film of the printing plate will be damaged, which will affect the lipophilic performance of the printing plate and reduce the printing resistance of the PS plate. If PS plates with strong alkaline resistance are developed with weak alkaline developer, the development will be incomplete, and the printing plate will be dirty during printing. Due to the long development time, the aluminum plate base will also be corroded to a certain extent, affecting the use effect of PS plates

dirt removal, glue wiping, drying

the PS version after development should be dirt removed. Before removing dirt, it is necessary to dry the PS version first, because most of the dirt removal parts are close to the image or text, and the revision paste will dissolve with the water on the surface of the base and spread around as soon as it comes into contact with the PS version, which is very easy to erode the image or text, making the edge of the image empty, the lines of the text shallow or the pen broken. When removing dirt, dip the tip of a brush into a small amount of revision paste, gently wipe the dirty areas that need to be repaired and completely remove them in the shortest time, and then rinse them immediately with water to avoid the revision paste drying up on the surface of the PS plate due to the long revision time

too long revision time is also easy to make the layout dirty. After the cleaning, wipe a layer of protective glue on the PS plate in time. If the glue is not wiped in time, the hydrophilic layer of the PS plate will be oxidized and the hydrophilic property will be reduced. During printing, the PS plate will be covered with control methods: experimental force, experimental speed, displacement, strain and other experimental methods can be selected. Correct glue wiping method: gently wipe a thin layer on the layout with a sand cloth dipped in an appropriate amount of glue, and apply it evenly, so that all hydrophilic layers are protected. After wiping the glue, blow dry the PS version, and then protect it

protection method: every two PS plates are separated by a neutral moisture-proof paper, and the storage temperature is 25. C, and the relative humidity is about 60

if the printing quality is in a stable state for a long time, the printing staff must have the spirit of love and dedication, constantly accumulate experience in work, and find a set of scientific standardized data suitable for printing and proofing, so that they can be handy at work, meet the current needs of large-scale printing plate drying, improve work efficiency and ensure product quality