In the printing industry (whether printed or printed), the PS plate is used as the transfer medium for offset printing. It is usually an aluminum alloy plate, with a thickness of 0.15~0.30mm and a layer of photosensitive liquid coated on the surface; according to different use occasions and requirements , size can choose or decide. 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 appropriate printing pressure by the lead roller, the blanket cylinder, and the three rollers of the 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 explains and discusses some of the details that should be noticed 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
Exposure is about to be coated with a photosensitive PS plate placed on the printer plate, put the film, through the main light, light exposure twice exposure so that the film on the pattern on the PS plate shows a basic "image" (conditions PS version The recommended exposure conditions are: (1) Potassium iodide lamp with a light source of 3KW; (2) Lamp plate distance of 1m).
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, and the layout should be centralized.
(1) When the plates are the same size as the sheet metal, attention should be paid to the ≥ 1mm in front of the plate and the crosshairs should be exposed, and the "+" lines should also be exposed on both sides;
(2) If the size of the sheet metal is surplus, it is necessary to negotiate with the customer about the location of the iron. For customers with special residual iron requirements, they must meet the corresponding standard requirements so that they are reserved during the printing process;
(3) When the plate size exceeds the size of the sheet metal, it can be exposed twice and exposed twice with the metal sheet to remove the original image. These are special circumstances, and the general plate-making needs to be consistent with the size of the sheet metal. This is both economical and reasonable and meets the technological requirements.
If the tinsel crown cover is printed with 0.23×712×512/MRT4, the size of the core is 712×505mm2. You can leave 1~3mm blank at the front of the printing, and leave 4~ 6mm clearance (In this example, refer to the Japanese 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 worktable. 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. Setting of exposure time: The main exposure time is usually set at 90~100s, and the light transmission is 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 part of the network cable, and at the same time the printing plate is resistant to printing force;
(2) The exposure time is not enough, the exposure is not enough, there will be a slight color pattern, empty and false;
(3) When the lamp performance deteriorates for a long time, the exposure time can be extended or replaced
5, PS version of the take: should be careful not to create a "dead mark", otherwise it is easy to print patterns blurred, ink emptiness, poor coloring.
Second, development
After the development, the exposed PS plate is placed flat on the developing tank to moisturize the developing solution. After about 1 minute, it is taken out and placed on the plate cleaning station. The coating dissolved in the plate is rinsed with water to show the image. ". The main points to note when developing:
1, the proportion of developer and water configuration, generally in the purchase of PS version with the distribution of a certain amount of developer, the ratio of developer and water is best to be slightly greater than or equal to the proportion of the original concentrate instructions, especially relative In summer. If the concentration of the developer is too large to clear the effective dots, the concentration will be insufficient, the development time will be longer, and the layout will be dirty and the durability of the PS plate will be affected.
2, the development time control. Under normal circumstances, about 1 minute after the PS plate is placed in the liquid crystal display tank (conspicuous bubbles appear on the surface during development). Developing too long will remove the “images†on the layout. If not enough time, the layout will be dirty.
3. If there are any extra spots or images on the plate after development, it can be removed with a revised paste, and then rinsed with water. (When repairing, you can use the brush to draw a moderate amount of paste to lightly apply to more than the image or spot. Rinse with water for a while).
4, the development temperature. It is suitable to be carried out at room temperature (23±2°C). Excessively high room temperature will deteriorate the reproducibility of the plate, and the low temperature will degrade the developing ability.
5, development should be carried out in the dark room to avoid natural light.
Third, protect the rubber After the development of the PS plate surface image parts and non-image parts must be painted with some gum arabic, to prevent the printing plate in the printing process dirty and layout abrasions, protection work is simple and easy However, in practice, it should also pay attention to the operation time, mainly in the following two aspects:
1, wipe the glue.
(1) After the developed PS plate is cleaned with water, wipe the excess surface moisture with a rubber scraper or sponge to apply the glue. Apply non-hair removal cotton towel or sponge to take appropriate amount of protective glue in the layout for vertical and horizontal cleaning, so that you can evenly thin flat (apply too thick and easy to peel off, too thin or uneven can not protect ).
(2) After the rubber is finished, the plate is placed on the workbench to dry (the fans can be used in summer, far infrared is used in winter, and it is easy to store and use, and those who have conditions can use the plate copy machine to have better results).
2, clear version. For the reusable printing plate, after each use, the surface of the ink can be cleaned with gasoline or ink cleaning agent, cleaning paste, etc. to expose the "primary color" and then gluing. In addition to paying attention to the above three basic links, the printing plate work should pay attention to the above three basic links. We also need to understand the day-to-day protection and school-based common sense that are closely related to it.
(1) School edition. The school edition is the proofreading and proofreading of the original proofs on the school's edition table, including: 1 draft surface size specification; 2 core size; 3 layout “+†word lines and “†lines are coincident; 4 graphic network lines are Clear; 5 the back of the film with no scratches and other scratches (if necessary, must use a non-transparent plastic bag or drawing pen, add a pen, to the pen to repair the layout).
Note: The plate size should be consistent with the size of the metal sheet; the layout must have the "+" word line and the "" center line, which is the basic sign of the standard version; the plate is usually marked with Y, M, C, K (representing yellow , magenta, blue, black) four basic marks, and -10% ~ 100% of the network line indicate the color bars above the layout, in order to show the sparse and contrast of the main line pattern.
(2) Storage and protection of printing plates. 1PS version should be stored to avoid moisture and high temperatures, the recommended storage conditions for the 10 °C ~ 30 °C, relative humidity is not greater than 65%, otherwise the layout of the alkali easy to damage the PS version; 2 indoor should be clean and dust-free, to prevent direct sunlight; 3 When reusable printing plates are stored, please pay attention to the relative layout of the plates, and at the same time, it is best to separate them with a paper lining; 4 If there are spots, scratches, etc. in the printing, the machine can be shut down and brushed on the plate. The printing solution and a small amount of fountain solution are added to the fountain to improve the print durability of the printing plate and obtain excellent printing quality.
In short, the printing plate is an auxiliary work for the preparation of the printing process. Although the process is relatively simple, the quality of the printing plate directly affects the quality of the printed product.
In view of the above, during the actual operation, in addition to paying attention to the basic operation steps in the printing process and various factors affecting the quality of the printing, the status and role of the printing plate in the printing process can not be ignored, because there is no qualified one. The standard version will not show any more beautiful designs.
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