Second, the layout of the dirty
1, the plate caused by the factors of the dirty
1 ps version of the base of the sand is too shallow, the amount of water caused by the non-graphic part of the dirty. Solution: When printing with this type of printing plate, increase the moisture content of the plate or add an appropriate amount of surfactant to the fountain solution to enhance the hydrophilicity of the non-graphical portion of the plate.
2 ps version base oxide film is thin and sparse, can not withstand the friction in the print and is worn out, the sand is bare and flat, the new water performance is reduced. Solution: Replace the plate again.
3 ps plate sealing is not sufficient, the plate surface remains unsealed microporous, the plate adsorption capacity is large, easy to absorb dust and other impurities; or sealing fluid contains calcium particles or other impurity ions, resulting in insoluble salts such as calcium silicate, pollution layout . Solution: Developed with a developer of calcium silicate as the main agent. At the same time as developing, the secondary plate is sealed.
4 ps version of the photosensitive adhesive layer is too thick, the normal exposure time can not be completely decomposed, the photosensitive adhesive residue in the inner wall of the sand, so that the non-graphic part of the oil from the increase of dirt. Solution: Extend the exposure time to completely decompose the adhesive layer.
2, PS version fog caused by the upper dirt
Due to improper storage of the PS version or inappropriate lighting of the interior of the printing plate, the PS version has fog, resulting in a non-graphical part of the printing plate having hydrophilicity and dirtiness.
Treatment: Protect the PS version from the light, and work under the safe light when printing.
3, the version on the dirty
1 Dirty due to improper exposure operations. The main reason is that there is dirt on the large printing glass or film to prevent the light from passing through, or the original film has a tape and border formed on the film. Solution: The former should deal with the detailed inspection of the part before the operation, and trim or use cleaning agent to dirty; the latter, when the area is small, remove the dirt remover, and when the area is large, the dispersive color film can be used for the double exposure method.
2 Insufficiency caused by underexposure. Different performance ps version photographic performance is not the same, so the exposure time is different. The exposure efficiency of the photo-resist layer is gradually decreasing with the photo-irradiation reaction. When the power of the light source is insufficient, part of the photosensitive layer is not completely decomposed, and it will become dirty. Therefore, each batch of PS version should measure the exposure, timely adjust the exposure time, while regularly checking the light source's effective power and voltage stability.
3 Impervious viscera. Mainly due to developer fatigue failure, the concentration is not enough, the developer temperature is too low or the development time is insufficient.
4 When preparing the developer, strong bases such as sodium hydroxide are used in excessive amounts, the alkali of the developer is too strong, the plate base oxide film is eroded, the substrate is exposed, and the hydrophilicity of the non-graphic part of the printing plate is decreased and the dirt is dirty. Solution: Add appropriate inhibitors such as potassium chloride or sodium phosphate to the developer.
4, change the dirty
1 Dirty on the altered area
Cause: The correction fluid has deteriorated; the surface of the plate has not been wiped when altered; the alteration is not sufficient; the alteration time is too long.
Solution: It is forbidden to change the printing plate with a modified fluid, and the correction fluid should be properly stored when it is not used.
2Dirty around the altered area
Causes: Underexposure or lack of development, there is residue in the photosensitive adhesive layer; the photosensitive adhesive layer that has been dissolved by the correction fluid is left around and adhered to the altered area; before the layout is reformed and the dirty is removed, the plate surface is wiped dry, Invaded around the correction department.