With the continuous development of printing technology, China's self-developed and manufactured Yang Tu PS version has been widely used in China. Compared with offset printing plates such as flat intaglio plates, the PS plate has the advantages of simple printing process, clear dots, and high resistance to printing force, but it sometimes loses its proper performance due to various undesirable factors. Because the author engaged in the PS version of regeneration, to some printing manufacturers, found that many manufacturers have appeared PS version does not ink failure, and the occurrence of this failure to buy more native PS version. This article would like to analyze the reasons for this failure from the following aspects for your reference.
First, the PS version of the storage environment and preservation period
So far, there are more than 20 PS plate manufacturers in China, and some regenerated PS plate manufacturers have also purchased aluminum plates to produce PS plates. The standardized management and production scale of each manufacturer are different, and the sales schedule and inventory period are also different. Due to the market economy, printing companies have a wide range of channels for buying the PS version, sometimes purchasing some P3 versions with a storage period of more than one year. This is the main reason why the PS version is not inked. In addition, some printing factories store PS version of the warehouse or copying workshop is not suitable for the PS version of the storage requirements, such as: the indoor is too humid, the light is too strong, the temperature is high, there is acid and alkali corrosion. These conditions will cause the PS plate to lose its proper performance, make the development of the exposure abnormal, and the ink-receptive performance is extremely poor. The printing on the machine will inevitably be difficult to apply ink or not to ink.
Second, the PS version of the grain status and photosensitive layer quality
Some printers purchased the PS version for a long period of storage. Storage and use of the environment are also satisfactory. However, there are also problems with non-inking. The reasons for this are analyzed. I think the main problem is the poor quality of the PS plate electrolyte sand and the photosensitive layer. Caused by factors. The specific reasons are as follows:
1. The PS plate needs to go through the production process of aluminum plate surface treatment before applying the photo-sensitive wave, in which the electro-sanding process is very important. If the treatment is not good, it will affect the next process and the printing and printing quality. The sand of the plate base consists of countless convex peaks and concave valleys. The concave valleys of the sand are deeper, and the valley bottoms are mostly on the same plane. The side walls from the peak to the valley are relatively steep. Such a structure can make the plate store enough moisture, and the blank portion of the plate is not easy to get dirty when printing, but if the convex peak is too high, the concave valley is too deep, and the side wall is too steep, it is not easy to uniformly coat the photosensitive liquid. After the PS plate has been exposed and developed, the protruding peaks of the sand grains are often difficult to reach due to the lack of a photosensitive layer covering.
2. The sensitizer used in the photosensitive liquid is less denier, so that the alkali resistance and the ink receptivity of the synthetic resin are extremely poor, and the photosensitive resist formulated with a sensitizer and the like is poor in alkali resistance, resulting in the development of a small portion of the image after etching by the developer. Dots, slender text, and thin lines are first dissolved and narrowed. If the development time is extended, not only the dot area of ​​the high-tone region and the intermediate tone region also has to be reduced, but also the performance and ink resistance of the PS plate are reduced.
3. The photosensitive liquid for coating has a high temperature, a high air humidity, and a long storage period. If the photosensitive layer is coated with it, the ink-receptive performance is extremely poor.
4. The sensitivity of the photosensitive liquid is too low, the photosensitive coating is too thin, the surface of the coating caused by various reasons is too smooth, and after the development of the printing plate, the ink is not painted. This printing on the PS plate is not easy to ink.
Third, printing and printing
In addition to the reasons for quality and preservation of the PS plate, improper operation in the printing and printing may also cause poor ink or ink failure.
1. The original graphic part of the density is too low. When printing, the original plate and the glass do not adhere tightly, and it is easy to cause poor alkali resistance in the graphic part after exposure and development, and loss of the photosensitive layer.
2. Overexposure, over-developed skin, and high concentration of sodium hydroxide in the developer will thin the photosensitive layer of the image after development.
3. PS version of the exposure, no ink after development, see the light for a long time, so that part of the photosensitive layer of graphic decomposition occurs, the color becomes light blue.