Discussion on evaluation standard of CTP plate

2022-07-26
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Talking about: CTP plate evaluation standard

for so many CTP plates in the market at present 4. with power down additional functional materials, what aspects should we evaluate CTP plates? What kind of plate meets our printing quality requirements

(1) point reproduction. Dots are the basis for printing and reproducing graphic information. The quality of printing plate dots will directly affect the quality of dots on the printed matter, and then affect the reproduction of the whole printing process. Therefore, it is very important to select plates with good dot reproducibility

ctp plate, like traditional PS plate, is also composed of sand mesh. In order to achieve 1% ~ 99% point reproduction of CTP plates, the sand mesh of the plate base must be small enough, because the finer the sand mesh, the more sand meshes supporting the highlights, the firmer the dots, and the less likely the plates will fall out during printing. However, the sand mesh of the dot cannot be too fine. The ink balance width of the plate with too fine sand mesh in printing is small, which is not conducive to the control of printing quality. The conversion formula is as follows:

(2) line reproduction. The reproduction ability of plate lines usually includes two aspects, the reproduction of very thin lines and the size of yin and Yang lines. The appearance of very fine lines is closely related to the size of the plate sand mesh, especially the uniformity of the sand mesh, because only the evenly distributed sand mesh supports the line edge can be smooth. The size of the yin-yang line is mainly determined by the coating thickness of the plate. We can compare the changes of lines by drying the adjacent negative and positive lines on the printing plate

(3) new ink. The ink affinity of plates refers to the feature that the image and text parts of the printing plate are selectively inked through the ink transfer roller. The thickness of the ink on the printing plate will directly affect the thickness of the ink on the blanket and paper, and the amount of ink transferred to the printing plate depends on the ink affinity of the printing plate. If the ink affinity of the image and text part of the printing plate is low, the smaller the range of ink control in the whole printing is, the worse the product quality is. Moreover, if a printing plate with poor ink affinity is used, the remaining ink will accumulate on the ink transfer roller, which thickens the ink film of the ink transfer roller, affecting the quality of drugs. There is too much ink at both ends, resulting in ink splashing and reducing the hiding power of the ink. Therefore, CTP plates with good ink affinity are very important

in order to improve the ink affinity of CTP plates, the photosensitive materials in the image and text part of the printing plate should have chemical properties similar to the pigments, resins and solvents in the ink

(4) leaders of the two countries can conduct in-depth exchanges on this issue. The hydrophilicity of plates refers to the characteristic of selectively keeping water on the non graphic parts of printing plates. The amount of water used in printing should be neither too much nor too little. Too little, the part without imprint is easy to get dirty; If there are too many, it is easy to have dim imprints, uneven paper receiving, paper deformation, inaccurate overprint, etc. At present, the main base material of CTP plate is aluminum, which is hydrophilic, and the surface is grinded to form a porous surface, which enhances the total surface area and finally improves the hydrophilic property

in addition, the factors that affect the performance of CTP plates include the resolution, printing resistance, bottomness, sensitivity, size, coating uniformity, etc

in a word, with the continuous progress of CTP plate making technology and the continuous improvement of CTP plate performance, the continuous emergence of CTP plate advantages and the continuous improvement of digital workflow, we have reason to believe that CTP plate will have a broader development prospect

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