Pre-press tips: CTP plate making puzzles
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CTP plate making is a comprehensive, multi-disciplinary product. It is a combination of optical technology, electronic technology, color digital image technology, computer hardware and software, precision instrument and plate technology, automation technology, network technology and other new technologies. High-tech technology. It is also prone to some problems, and Xiaobian has compiled the following solutions for you.
Upper viscera means that there are dirty spots, lines or strips in the graphic area and non-image area on the printing plate, resulting in dirty matter on the printed matter. The main factors that cause the dirty on the plate are the following.
(1) There are quality problems in the CTP plate itself, such as poor production processing, insufficient water storage capacity of the sand, and fluctuations in the performance of the plate batch.
(2) When the CTP version is output, there is a problem in the development process, which causes the plate to remain at the bottom. Therefore, it is necessary to pay attention to check the exposure amount or the degree of aging of the syrup; whether the dilution ratio of the protective glue is appropriate, whether it is deteriorated; whether the revision plate damages the aluminum plate base or the like.
(3) The dampening solution used in the printing machine does not match the printing plate or the water in the water tank is not properly formulated, and the acidity is high; the ink viscosity is low, the emulsification is severe; the ink roller has a large amount of ink or the ink roller is aged.
Before the CTP version, some printing companies would clean the layout with a cleaning solution to prevent the printing from getting dirty. However, care must be taken to ensure that the cleaning solution does not harm the CTP version of the coating, otherwise it will cause the plate to disappear. When the printing plate is dirty, if it can be wiped off with the cleaning solution, it means that it is dirty, not because the printing plate is not washed out; if it needs to be removed with a finishing pen, the printing plate is not washed out.
If the ink is not printed, the printing image area is not inked or unevenly printed, as shown in the figure. The main factors that cause the printing plate to not be inked are as follows.
(1) The quality of the plate material or the syrup itself is problematic; the development is excessive, the plate coating loss is serious; the protective glue is too thick, and it takes a long time to rely on the water roller or the cleaning plate to wipe the plate.
(2) The printing machine is large in water; the viscosity of the ink is too large, resulting in deinking or poor ink supply; the paper is out of powder and the hair is pulled seriously; the dampening solution does not match the printing plate or the water ratio in the water tank is not suitable.
(3) The printing plate coating has been worn or corroded, it is not very good to be inked, and a new version needs to be replaced.
Broken plates are mainly found on rotary presses because of the fast production speed of the rotary press, which requires that the size of the plate in the direction of the drum is very precise, and the graining direction (Graining direction) is perpendicular to the axis of the plate. However, due to the slower production speed of the sheetfed press, there is no requirement for the grain direction of the printing plate. Other reasons that may cause the plate to break are: there is a problem with the plate, the plate is not square, the plate size is wrong, and the package is too short.
The quality of the retained version is declining
Some prints that are not high enough but need to be turned over, in order to pursue color consistency and cost savings, often need to retain used plates. In addition to the performance of the plate itself, the quality of the plate is also related to the retention method and storage conditions. Plates retained by experienced operators can be reused 2 to 3 times. Here, the roughing process is provided. The printing company can make some adjustments according to the actual situation. It is recommended to use the machine operation.
(1) Clean the plate. The ink should be washed off as soon as possible after the plate has been removed from the press. The chemicals used to clean the plates must have little damage to the plate coating, otherwise the coating loss will be severe and the plate loss will occur soon after re-use.
(2) Clean the plate. After cleaning the ink on the plate, thoroughly clean the chemicals on the plate with water to prevent the residual material from damaging the plate coating.
(3) Storage. After the first two steps are completed, apply a protective glue evenly on the layout. After the protective adhesive is dried, cover the backing paper and place it in a dry and ventilated environment. Note that you should choose to use a protective adhesive with long-term protection. The ordinary protective adhesive can only protect the printing plate for about 7 days.