In the printing industry (whether it is printing paper or printing iron), the PS plate is used as the medium for lithographic offset printing. It is usually an aluminum alloy plate with a thickness of 0.15-0.30mm and is coated with a layer of photosensitive liquid; it is used according to different occasions. Requirements, size can be selected or decided. In the printing industry, the printing pattern is transferred to the surface of the iron sheet through the principle of ink-ink balance under the proper printing pressure by the three-drums of printing plate cylinder, blanket cylinder and impression cylinder. The quality of the printing plate depends on the PS plate. The process of drying and other influencing factors, it should be said that the quality of the printing plate is a prerequisite and fundamental for the quality assurance of printed products.
This article only describes and discusses some of the details that should be noted in the process of drying the PS plate.
PS printing process can be simply illustrated as three basic links, namely exposure - development - protective plastic.
One, exposure
The exposure of the PS plate with the photosensitive layer is placed on the platen of the plate, the film is placed, and the pattern on the plate is displayed on the PS plate by double exposure of the main light and the light transmission. (Note: Each model For the PS version, it is recommended to use a 1KW light source with a 3kW iodine lamp and a 1M lamp version.
The work program of the printing plate is controlled automatically, but pay attention to the following basic details, mainly including:
1. The position of fangs or bite should meet the technological requirements. (1) When the plates are the same size as the sheet metal, it should be noted that the 1mm in front of the layout must show crosshairs in left-empty county, and the left and right sides should also expose the + word line; (2) If the sheet size is surplus, it is necessary to negotiate with the merchants clearly. The position of the iron is left blank; for customers with special residual iron requirements, they must meet the corresponding standard requirements, so that they are reserved during the printing; (3) When the size of the printing plate exceeds the size of the metal sheet, the original position can be covered with the iron sheet after the exposure. Expose and remove unwanted images. These are special circumstances, and the general version must be consistent with the size of the sheet metal, so that it is economical and reasonable and meets the process requirements.
For example, when using the 0.23*712*512/MRT4 tinplate as the crown cover, the size of the core is 712*505mm2. When the printing is in front of the printing version, the blank space can be appropriately 1-3mm, and the position of the teeth can be set aside. 6mm gap (this example refers to Japan Fuji Machinery PRIMEX-F450 printing plate description).
2. Before starting the power of the printing machine, it is necessary to check whether there are foreign objects such as a ruler and a revised knife on the work table. Otherwise, the glass frame of the machine table will be exploded.
3. After positioning the PS plate to be positioned, it must be noted that the vacuum vents on the side of the machine table must not be covered.
4, the setting of exposure time: the main exposure time is usually set at 90-100S, auxiliary light at 15-20S. (1) The exposure time is too long, the pattern on the PS plate is brittle, and it is easy to fall off and lose some of the cable, and the printing plate is resistant to printing force; (2) The exposure time is not enough, and the exposure is not enough, the color of the pattern will appear light and empty. False; (3) When the lamp's long-term use performance deteriorates, the exposure time can be extended or replaced.
5, PS version of the take: should be careful not to make a "dead mark", otherwise it is easy to print patterns blurred, ink emptiness, poor coloring.
(to be continued)