The basic technical requirement for making PS plate is smooth and flat surface, no scratches, pits, imprints, non-gold crawler indentation, porosity, rolling stripes and other apparent defects, uniform thickness, waviness within 1 mm, flatness less than 2 I; fine and uniform microstructure, no segregation, slag inclusion, internal stress from symmetrical and uniform The roughness Ra value is less than 0.28, so as to ensure that the electrolytic sand mesh is fine and uniform. At present, 1050A, 1060 and so on are widely used in China.
B alkali washing
Usually, the surface of aluminium sheet provided by aluminum processing plant contains a certain amount of oil. Oil and oxide film have an impact on sand treatment. In PS plate production, hot-alkali washing aluminium sheet is often used for surface treatment.
Usually alkali solution is used to remove oxide film and oil. The common proportion of degreasing solution is NaOH mass sodium and other corrosion inhibitors, sodium gluconate, fatty acid polyoxyethylene ether solubilization, complexation and other surfactants.
The temperature of the degreasing fluid is usually controlled at about 55~60 degrees. The effect of oil removal is related to the temperature of the solution. If the temperature is too high, the generator will seriously corrode the aluminum plate foundation, so the temperature must be controlled.
The time of oil removal must be carefully contrasted and finalized. Because it is related to various production lines. The drum production line is related to the speed of the production line. Take 4m/min as an example, the oil removal time must reach 20s, and the effect can be guaranteed.
Oil removal liquid must be updated in time, because a large number of saponifiers, emulsifiers and aluminum salts will be generated in the process of oil removal. Their existence affects the effect of oil removal, and hinders the saponification and emulsification of oil stains on the surface of aluminum plate. When it is found that the effect of oil removal is not strong, it must be updated in time. Usually, when circulating through the alkali pump, the oil removal liquid can be maintained for a long time, if not, the renewal time will be shortened.
The easiest way to check the degreasing effect is to use water. The water on the surface of aluminum plate with good degreasing effect can be uniformly adhered and dispersed. If the water is poured on the surface of aluminum plate, the degreasing effect is not good. The temperature of the oil should be paid attention to frequently. Besides the low temperature of the oil, it may cause oil removal.
In the production process, there is a nitric acid pickling process after alkali washing. The purpose is to remove the residual substances after alkali washing and neutralize the residual lye. The mass concentration of nitric acid is 5% to 10%. When preparing, carefully pour nitric acid into the water and mix it well. In the pickling process, we should pay attention to the concentration analysis of the solution and replenish it in time.
The coarsening is to form the sand mesh structure with required roughness. Coarsening can not only improve the affinity of water on the surface of aluminum plate, improve the wettability of the surface of aluminum plate and prevent the plate from dirty, but also improve the adhesion of the plate with the photosensitizer, thereby improving the printing endurance of the plate.
Coarsened sand mesh is composed of numerous peaks and valleys. Different sand mesh structures have great influence on the adhesion of water-holding photosensitive layer and the use of PS plate. Characteristic parameters of rough section contour curve of sand mesh drawn by surface roughness tester are used to characterize the curve.
I believe that after reading the introduction of this article, the aluminum plate manufacturer will also have their own understanding of the future for such problems can be well solved.