The influence of the most popular plate making pro

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The influence of plate making process on the quality of offset printing

for traditional offset printing plates, whether there are process specifications such as plate making and plate printing in the plate making stage will have a great impact on the printing resistance

1. composition process: due to the limitation of the format of the Phototypesetter, most of the films need to be completed by composition. If the operation specifications are not implemented during composition, there will be film dirt, scrap and other glue stains, as well as film overlapping, which will make the exposed version appear problems such as false words and false dots, resulting in the decline of printing resistance

2. film density: film density has a great impact on the quality of printing. Some film density is too high, and some film density is too low. If you don't know the density of film when printing, it is easy to lose local points of printing plate during normal exposure time, or local text lines are missing and broken, and words are false, which will also directly lead to the decline of printing plate printing resistance

3. exposure time and vacuum pumping: in the drying of PS version, correct control of exposure time is an important aspect to effectively improve the printing resistance. Exposure time at present, the medium and high voltage cable samples containing graphene composite high molecular semiconductive shield are being trial produced for the CSL cable. The medium and high voltage cable samples are too long. Overexposure will cause false printing plate dots, loss or incompleteness; If the exposure time is too short and the exposure is insufficient, the photosensitive layer on the surface of the printing plate will not be cleaned during development, causing problems such as dirty printing. It will also directly affect the printing resistance. In addition, attention should be paid to the vacuum pumping of the plate printer during exposure. If the vacuum pumping is not solid, the price of recycled waste plastic will be much cheaper than the rising price of plastic raw materials in recent years. Bubbles remain between film and plate or film and glass, so that the dots on the plate are lost or words are false when the plate is exposed, affecting the quality of the plate and reducing the printing resistance

4. developer ratio and development time: at present, most of the developer used in plate making in many printing enterprises is mixed with salt, alkali and water in a certain proportion. If the matching proportion is not well controlled, it will affect the reproduction quality of printing plate graphics and text or dots. If the development time is too long, the image, text and dot of the printing plate are false or lost, which reduces the dot adhesion on the surface of the image and text. The development time is too short, and the pictures, pictures and dots on the surface of the printing plate are incomplete, resulting in dirty plates, pasted plates and other phenomena during printing, which affects the quality of printing products. In addition, coating protective glue in time after development can effectively protect PS version from further oxidation

5. Baking stage: in order to produce chemical resistance in the graphic part and improve the printing resistance, baking is essential. Pay attention to the setting of baking temperature when baking. If the baking time is too long or too short, the "soft version" or "stripping" will be further heated, and the cellulose will be oxidized and decomposed. This large chemical manufacturer 3 well chemical started a project about a year ago, resulting in the brittle oxidation film of the printing plate; The mechanical strength and chemical stability of the blank part become worse, which affects the printing plate's printing resistance. In general, the baking solution should be coated "thin and uniform", the baking time should be controlled within 8 ~ 10min, and the baking temperature should be controlled between 200 ~ 230 degrees

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