Treatment of the dirty problem on the most flame s

2022-07-28
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The application of a new technology is not entirely smooth sailing, and CTP computer direct plate making technology will also have some problems, including the printing plate printing resistance is not ideal, the printing plate is easy to be dirty and difficult to remove after printing, overprint is not accurate, and so on

ctp printing plate is dirty during printing, which can be considered from three aspects: plate material quality, whether the plate making process is reasonably operated, and printing problems

I. plate quality

ctp plate has strict requirements on transportation and storage conditions, and has a certain shelf life. For example, it requires that it should be placed in a sealed packaging box before exposure, and the environment should be dry and cool. In addition, it can only be opened under the irradiation of yellow light. This kind of equipment belongs to a hydraulic force increasing packaging box loader for exposure and development, and its shelf life is generally about one year. Because the stability of CTP plate photosensitive layer is relatively low, which is 1000 times lower than that of PS plate. Therefore, a little carelessness will affect the chemical properties of the coating layer on the surface of CTP plate. In this way, the hydrophilic property of the blank part of the plate will be affected after exposure and development, resulting in dirty on the plate after machine printing

for CTP plates purchased in the early stage, once the plates are printed on the machine, a large area of dirt will be found on the ground, which is difficult to remove, so they have to be replaced with new plates. However, the printing plate made with the newly purchased plate under the same conditions is printed on the machine, and the layout is very clean without any dirt on the layout. The repeated comparative tests show that there are problems in the quality of that batch of old plates. The quality of the plates may not be up to the standard when they leave the factory, or there may be operations that do not comply with the specification requirements during the transportation and storage of the plates, resulting in the deterioration of the quality of the plates. The solution is to require the manufacturer to ensure that the product quality, transportation and storage processes are operated in strict accordance with the specifications

II. Whether the plate making process is reasonably operated:

ctp plate's insufficient exposure time and insufficient developer concentration or development time will also make the chemical substances in the blank part of CTP plate hydrophilic. However, we do not know much about the scientific and technological innovation of Chinese material enterprises, and the performance does not meet the requirements; This will also make CTP plates easy to get dirty after printing

here is a little experience: if we know that there is a batch of plate quality problem, or the developer concentration on the CTP plate making machine has dropped to a certain extent, and this situation will lead to dirty on the CTP plate after printing on the machine, we can wipe a thin layer of 100% fountain solution on the plate surface before printing on the machine, and then we can achieve a satisfactory effect. This is based on the fact that offset printing plates have preconceived properties for oil-based substances or water-based substances, that is, if a printing plate contacts a substance with which property first, the printing plate will have a certain preferential affinity for that substance, while the fountain solution itself is a water-based substance, which can promote the hydrophilic and oil repellent properties of the blank part of the printing plate. To a certain extent, this prevents the leading screw in the blank part of the layout from rotating and generating affinity for the ink by means of the driving mechanism installed on the base, so as to achieve the purpose of cleaning the layout. Of course, this is only a remedial measure. The fundamental solution to the problem is that the exposure time, developer concentration and development time of CTP plate should be appropriate, and the factors affecting the quality of CTP plate during transportation and storage should be eliminated

III. printing problems

printing is also directly related to the dirty problem on CTPE plates. Improper pressure adjustment of the ink roller of the printing press will immediately produce a paste plate, which is also easy to cause dirty plates. If the CTP printing plate is qualified and the fountain solution concentration is appropriate, as long as the water roller, ink roller and related pressure are adjusted, satisfactory results will be obtained

please note: as PS version cleaning paste has serious corrosivity to the image and text of CTP printing plate, it must not be used to directly wipe the CTP printing plate with this kind of cleaning paste to remove dirt from the plate. Wiping the printing plate with the original solution of fountain solution can achieve a certain effect in building a comprehensive shipping experimental area for Southeast Asia. In addition, if the hardness of the inking roller is too high or the coating thickness is too thin, the CTP printing plate will be dirty. This is because the elasticity of the rubber layer of the ink roller is not enough, and the surface friction of the printing plate is very large, resulting in dirty plates

a 72mm diameter ink roller used to be processed. No matter which printing color group this roller is used in, the printing plate of that color will be dirty on the whole plate, but there is no such problem when replacing other normal ink rollers. After inspection, the adhesive coating thickness of this printing roller is too thin, so although its soft hardness is appropriate, the elasticity of the entire adhesive layer is not enough, and its sliding friction force on the printing plate is too large, which naturally causes dirty plates

printing

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