As the PS version has a high degree of dot reduction and high resistance to printing, it has always had an irreplaceable position in the printing process.
The PS plate is mainly composed of two layers, the photosensitive layer and the plate base. The excellent PS plate needs to have the following characteristics in addition to the photosensitive layer and good hydrophilicity of the plate base, including: uniform thickness, It is dimensionally stable, not easily deformed, has no dirt on the surface, and has a strong photosensitive layer, which allows the PS plate to have good abrasion resistance and resistance to printing forces.
In addition to the above basic requirements, the following four precautions will help you avoid the various problems that occur in the process of printing, developing and printing, and affect the performance of the printing plate:
1. First of all, the glass of the printing machine should be kept clean so that the image does not faint and the blank is not clean. If the printing machine is used for a period of time, it is necessary to check whether the degree of vacuum of the air pump is sufficient; if there is a small amount of air leakage due to aging at the edge, the PS version and the film will not stick tightly, and the printed image will be blurred. . In addition, we must also pay attention to whether the dots on the printing film have enough blackness. If not, the dots on the printing plate will not be solid, and the dots will be thrown off when printing. In addition, if the exposure is not enough or the medicine is too concentrated during the process of printing, it will also result in the fact that the detailed part cannot be reflected.
2. The temperature of the developer, the processing speed of the processor, and the development time must be appropriately matched. If the temperature of the developer is too low, the processing speed of the plate processor is too fast, the development time is too short, the development will be insufficient, and the plate will not be washed cleanly. Regular cleaning of the crystals in the processor tank and the pipe wall to remove dirt and keep the brush on the machine clean, are some good methods, if necessary, replace the filter element of the developer, to avoid the non-graphic part of the printing plate Dirty spots.
3. During the process of applying the protective glue, it is necessary to apply the glue evenly, and to use a glue solution of a moderate concentration, otherwise the non-graphic part will be oxidized to make the plate dirty. If it is really dirty, there are ways to save it. First of all, a dirty plate can be dirty with a cleaning fluid. Please keep in mind: When the cleaning fluid is used, be sure to screw the lid on. Second, after the plates are dirty, they must be thoroughly cleaned and glued with clean water. When the plates are completely dried, they can be printed.
4. Bake the PS plate with the proper time and temperature. In general, after the PS plate is baked, the abrasion resistance of the graphic part can be enhanced. In other words, the resistance to printing can be increased. However, if the high-concentration protective agent is used or the coating is uneven during the baking process, the protective agent hardens and solidifies on the printing plate, resulting in no ink absorption. To avoid this, pay attention to the color of the photosensitive layer after baking, which is normally reddish-brown. If the color is dark brown or dark brown, it means the baking temperature is too high or too long, which will only reduce the PS version. The resistance to force.