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In the printing industry (whether printing paper or iron), the PS plate is used as a transmission medium for offset printing. It is usually an aluminum alloy plate with a thickness of 0.15 to 0.30 mm and a layer of photosensitive liquid on the surface. The quality of the printing plate depends on the printing process of the PS version 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 explains and discusses some details that the PS version should pay attention to during the drying process.
1. PS version printing
(1) Monochrome lines, the edges of the film base and the traces of adhesive tape will remain on the printing plate when the text version is printed, and you must carefully remove the dirt. Some of the original text lines are not black enough, especially the horizontal strokes of the Song typeface are relatively thin. If the printing time is too long, the line will be broken and the painting will be missing; if the pattern is not black enough, the printing time is long, the PS version will lose gloss after development, and the ink performance will be poor when printing , Affecting the printing quality.
(2) The printing time of such monochromatic dot version should not be too much, especially to prevent 3% of small dots from disappearing due to too much printing time.
(3) Monochrome large solids but with reversed lines of text lines, because it is large solids, the amount of ink must be large when printing, to ensure that the solid ink color is sufficient, but after the amount of ink is increased, the text lines are reversed. It's easy to paste. This type of original is mainly determined by the size of the text and the thickness of the lines in the highlight. The smaller the text, the thinner the lines, and the more the exposure time, in order to make the thin lines and the reversed strokes of the small text thicker, it is not easy to paste the plate when printing.
(4) In the color gradation version, there is no flat screen, but there is a large headline or pattern on the field of plate making, this situation often occurs: the dot color of the printed part is enough, but the color of the solid part is not enough, the ink layer If it is not thick enough, if the amount of ink is increased, the color of the solid part is enough, but the dot increase is serious. If the printing time is properly increased, the dots are reduced, that is, the printing plate is lightly exposed, which can make up for the phenomenon of dots increased due to the large amount of ink on the ground.
2. PS version development
In the PS plate making, development is also one of the key steps, so it is necessary to always check whether the development conditions are correct, and correct development conditions can ensure that the PS plate produces a high-quality printing plate.
(1) Insufficient development may result in dirty and enlarged dots on the positive plate; excessive development may cause shrinkage of the positive plates and dots.
(2) If the developer is fatigued, the same exposure will cause insufficient development.
(3) When the machine is developed, immerse all the exposed plates in the diluted developing solution, and start the timekeeping at the same time. During the development process, the groove body must be continually oscillated to develop the plate evenly.
(4) During manual development, place the exposed PS plate on the development platform, pour the developing solution to its central part, the amount of liquid is about 200ml / m2, use a sponge to wipe the figure-filled solution repeatedly in a continuous manner. Plate; for large-size plates, it is best to use a squeegee to move back and forth on the plate to remove the dissolved coating, and then rinse the plate with tap water.
(5) Special attention should be paid to the development of the light-printed PS plate. The light-printed PS plate base is only 0.15 mm thick, and the plate base is relatively thin, so be careful and handle gently to avoid damage to the plate during the development process. During the development of the light printing PS plate machine, in order to protect the plate from damage, it is recommended to use a large flat ordinary PS plate as the pallet, attach the light printing PS plate to be developed to it, and then develop the machine.
(6) It is recommended that the developing operation room should be equipped with yellow lights and yellow curtains to avoid natural light. After the development is complete, the positive image should still be placed in this environment; the negative image plate can be placed under natural light and incandescent lamp after the revision is completed.
(7) There is an automatic replenishment operation for machine development to replenish the development replenishment solution, so that the developer maintains a good development capability. Generally, a sensor placed in the developer is used to measure the conductivity, and the developer fatigue rate is calculated and supplemented accordingly. However, the sensor is easily covered by developer components and dirt, so it should be cleaned regularly. If the developer is not clean, then the developer replenisher cannot be replenished correctly.
3. PS version revision
3.1. Because the photosensitive film after baking is very firm on the plate, PS plate must be cleaned of the tape and dirty spots before baking.
3.2. Rinse the revision liquid with clean water after revision, otherwise, after baking, the residual revision liquid and the dissolved substances will contaminate the surface and cause dirty
4. PS version glue
If the water in the rinsing equipment is brought into the glue tank on the developing machine, the protective glue is diluted. Can cause stains on the media.
If the glue solution is too thin, the protective glue layer on the plate is too thin, and it is easy to get dirty or scratched.
If the glue solution is too thick, the protective glue layer on the plate is too thick and seriously uneven, and it is easy to cause ink-free, cracking and plate-off phenomena.
If there is a drying section on the gluing machine, overheating of the drying section can cause the protective glue to stick to the roller; the drying temperature should be around 60 ℃. Clean the air circulation filter once a month.
When the air filter becomes clogged, it heats up, making operation unstable.
5. PS version baked version
1) Apply an appropriate amount of baking adhesive to the surface of the plate, and use a sponge to wipe the entire surface evenly. Baking glue cannot be wiped off with a dry cloth.
2) The plate is baked in a plate oven, and the entire image area will change color evenly. Different PS version baking time, temperature conditions and final color will be inconsistent, so it is necessary to determine by experiment.
3) If the baking paste is too thick, the inking effect is not satisfactory. If the baking glue is too thin, it is easy to get dirty.
4) If the baking time is too long or the temperature is too high, it will cause dirty. If the temperature is higher, the aluminum base will be toughened and softened, affecting the printing durability and even the use.
5) If the baking time is too short or the temperature is too low, the baking effect will not be achieved. The negative PS version can improve the durability by developing and then exposing.
Sun Kee Envelopes Limited , https://www.sunkeeenvelope.com