Positive PS version does not ink failure analysis

With the continuous development of printing technology, China's self-developed and manufactured Yang Tu PS version has been widely used in China. Comparing with offset printing plates such as flat intaglio plate, PS plate has the advantages of simple printing process, clear dots and high resistance to printing force. However, it sometimes loses its 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 nearly 20 domestic PS version of the manufacturer, some manufacturers of renewable PS version also purchased aluminum version of the base production PS version. 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 ink or not.
Second, the PS version of the grain status and the quality of the photosensitive layer Some printing manufacturers purchase PS version of the storage period is not long, storage and use of the environment are also desirable, but there will be no ink failure, analysis of the reasons, I think the main PS version electrolytic sand shape and photosensitive layer caused by poor quality factors. The specific reasons are as follows:
1. The PS plate needs to go through the production process of aluminum plate surface treatment before coating the photo wave, in which the electrolytic sand grain 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 part 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 is exposed and developed, the protruding peaks often cause difficulties in the upper part due to the absence of the 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 the sensitizer and the like is poor in alkali resistance, resulting in the development of the developer and the erosion of the graphic portion. Dots, slender text, and thin lines are first dissolved and narrowed. If the development time is prolonged, not only the dot area of ​​the high-tone region and the intermediate tone region but also the area of ​​the halftone dot of the intermediate tone region will be reduced, and the ink-absorbing performance and the resistance force of the PS plate will be 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 aspects in addition to the PS version of the quality and preservation of the reasons, improper printing and printing operations, will 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 of the graphic part after exposure and development, and loss of the photosensitive layer.
2. Excessive exposure, 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.
4. During the second development of the baking plate, the protective agent on the plate could not be completely removed. As the protective agent contains emulsifier, if left on the plate will cause ink emulsification. Reducing the ink-absorbing performance of the graphic part will not absorb ink in severe cases. Concentration of protective agent...
5. Due to the low winter room temperature and the thickening of the ink, it is necessary to add a dilute ink to adjust the dilution. In this case, the amount of water in the layout needs to be increased (because of the large fluidity and large oiliness of the ink, it is easy to get dirty). In particular, the early mastery of the school edition is not good, and the amount of water tends to be large. The large ink thin ink causes ink emulsification and reduces the ink-absorbing performance of the graphic part. If the photosensitive layer of the graphic part is too thin and the density is poor, it will cause ink absorption failure.
6. As the printing plate or printing plate used for the protection of the plastic deterioration, so that the surface of the film before printing is not clean, in the ink when the channel does not appear ink failure.
7. Plates that are down but still available are generally reserved to prevent their use. However, due to the fact that the layout is not cleaned after the machine is closed, the sealant or glue is not evenly rubbed, and when the screen is not wiped cleanly, it will not be inked or dirty.
8. In the graphic part of the printing plate, under the repeated rubbing of the water roller, the ink roller, the rubber roller, the paper powder and the paper hair, the photosensitive layer is gradually destroyed, the lipophilicity is weakened, the hydrophilicity is enhanced, and the wetting liquid is given to the printing plate. When it is excessive, the fountain solution adheres to the graphic part, forming a layer of water-retaining film, resulting in inability to ink.