Preservation and application of CTP plate of the h

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Preservation and use methods of silver salt CTP plates in recent years, the number of silver salt CTP plates used in newspaper printing is increasing day by day, and the daily consumption of silver salt plates is also very large. Users also pay more attention to the problems in the use process. Based on years of production experience, the author believes that the preservation of silver salt CTP plates and related production conditions are closely related to the printing quality, especially the printing quality of newspapers. Sometimes the adverse factors in the process may even bring disastrous consequences to the printing

we analyze some easily neglected problems of silver salt CTP plate from two aspects of storage and use

1. Problems in the storage of silver salt CTP plates

generally speaking, the storage conditions of silver salt CTP plates that we often pay attention to include temperature and humidity. The storage temperature is required to be lower than 30 ℃, and the humidity is 30% ~ 70%; The best storage temperature is 23 ℃ and humidity is 50%. The shelf life of silver salt plates is usually 36 months. For newspaper printing, due to the large amount of plates used, they can be basically stored and used as required. In addition to the general storage requirements, we should also pay attention to the following issues:

① we usually note that the temperature and humidity should not be too high. If the temperature is higher than 30 ℃, the photosensitivity of the film will be greatly reduced. But at the same time, the humidity and temperature should not be too low

storage humidity is too low, which is easy to cause static electricity to accumulate in the PS version. Under the action of static electricity, the PS plate is easy to produce sparks during separation, resulting in partial light loss of the PS plate. In addition, due to the adsorption of static electricity, the spacer paper is stuck to the PS plate, and the CTP automatic paper removal device fails, resulting in plate jamming. What's more, it makes the spacer paper enter the plate punching machine, causing the circulation of the plate punching machine. 4. During the maintenance of the tension machine, the upper ring pump of the experimental project is blocked, and the circulating pump needs to be removed for cleaning. It causes a lot of time loss, which is huge and irreparable for newspapers that pay attention to practical results

in addition, if the storage temperature is too low, the temperature difference between the storage environment and the use environment will be too large, and moisture will condense on the PS plate, damaging the photosensitive layer, resulting in the failure of the PS plate

② when saving the PS version, be sure to stack it smoothly. Due to the heavy weight of plates, the shelves for stacking plates sometimes deform under the action of gravity, resulting in the deformation of PS plates at the bottom. These plates often get stuck in the plate punching machine during use, causing production interruption and even damaging the rubber rollers of the plate punching machine

③ storage location. In newspaper printing, the unqualified P5 group is all polyurethane s version, which is used in a large amount. There are often multiple batches of PS version in the warehouse, so we must pay attention to it during storage. First of all, the PS versions of different batches should be stored separately and marked to avoid confusion, which will cause the PS version to be expired. Secondly, pay attention to the stacking order. The new version is inside and the old version is outside. Otherwise, because the stacked PS version weighs a lot, it is a very difficult task to bypass the new version and use the old version

2. Problems in the use of silver salt CTP plate

silver salt CTP plate is a mature plate with stable process. But sometimes something unexpected happens

① the blank part of the printing plate is dirty. In the case that the quality of plates and potions is OK and the exposure is correct, it is caused by insufficient washing of the plate making machine. At this time, we should check whether the nozzles of the washing part of the plate punching machine are blocked. In addition, aging of the cots and insufficient pressure between the cots will lead to the above situation

② the graphic part of the printing plate is not inked. Such problems are highly hidden and can not be found in the process of plate making until they are printed on the machine, which will cause a lot of waste of PS plates and irreparable loss of time for newspaper publishing

there are several factors that can cause such problems. First of all, the current printing machines are all automatic timing and quantitative replenishment of potions. In addition to excluding the factors such as filling wrong liquid medicine, it is necessary to check whether the automatic replenishment of liquid medicine of the plate making machine with the economic warming is normal, and pay special attention to whether the liquid medicine extraction pump of the plate making machine operates normally. Secondly, silver salt CTP plates have a protective layer. If this layer is not cleaned in the plate punching machine, it will remain on the PS plate, and the printing plate will not be inked during printing. The cause of this situation is that the nozzle of the washing part of the plate washing machine is blocked

③ the printing plate durability decreased. Silver salt CTP version of the general printing rate can reach about 200000, such as impact. Sometimes, if the printing resistance drops sharply, and the plates are ground after less than tens of thousands of copies, in addition to considering whether the rubber rollers of the plate punching machine are clean, whether the potion is normal, whether the printing machine is in normal state, and whether the fountain solution used in printing is correct, there is another problem that is less noticed, that is, whether the pH of the tap water used in the plate punching machine is normal. The author once encountered such a problem. During the production, the printing resistance of CTP plate dropped sharply, and a large number of plates were ground before printing for less than twenty or thirty thousand. Check that the CTP, the plate making machine and the printing machine are in normal condition, and the potion during plate making and the fountain solution during printing are normal. Finally, various factors were eliminated and the problem was found to be caused by the tap water used. As the reservoir was cleaned on the same day, it was found that the pH value exceeded the normal range after testing, it was estimated that the detergent was not washed clean during cleaning. After the property department replaced the water in the reservoir, everything was normal

to sum up, silver salt CTP plate has been a quite mature plate after ten years of large-scale use. The CTP process is stable, but if we can pay attention to the following points in production, we can still reduce the occurrence of use failures and reduce the scrap rate

pay attention to the storage conditions of CTP plates, such as appropriate temperature and humidity, whether the supports are flat during stacking, the opposite order of new and old plates, etc. Strengthen the maintenance of the offset plate machine. After cleaning the offset plate machine, carefully check whether the cots are worn, whether the nozzles are smooth, and whether each circulating pump and make-up pump operate normally. Try to find the fault in advance to avoid the loss of time and benefit

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