Alkali washing
Generally, the surface of the aluminum plate supplied by the aluminum sheet processing plant contains a certain amount of oil. The oil and oxide film have an impact on the sand mesh disposal. In the production of PS plate, hot alkali is often used to wash the aluminum plate for surface disposal.
Alkaline solution is generally used to remove oxide film and oil. The ratio of commonly used degreasing solution is: corrosion inhibitor such as sodium mass of NaOH and surfactant such as sodium gluconate, fatty acid polyoxyethylene ether solubilization and complexation.
The temperature of degreasing fluid is generally controlled at about 55 ~ 60 ℃, and the role of degreasing is related to the temperature of the solution. If the temperature is too high, the manufacturer will seriously corrode the aluminum plate base, so it is necessary to control the temperature.
The time of degreasing needs to be determined through careful comparison. Because, it is related to various different production lines. The reel production line is related to the speed of the production line. Taking 4m / min as an example, it is necessary to remove oil for 20 s at any time to ensure its function.
It is necessary to update the degreasing fluid in time. Because a lot of saponifiers, emulsions and aluminum salts will be generated in the degreasing process, their existence will affect the degreasing effect and prevent the saponification and emulsification of oil on the surface of aluminum plate. When it is found that the degreasing effect is not strong, it is necessary to update it in time. Generally, when circulating through the alkali pump, the degreasing fluid can last for a long time. If it does not circulate, the renewal time will be shortened.
A simpler way to check the degreasing effect is to use water. The water on the surface of the aluminum plate with good degreasing effect can be evenly attached and lax. If the water is in the shape of water droplets on the surface of the aluminum plate after pouring, it indicates that the degreasing effect is not good. Pay attention to the temperature of oil removal. If the temperature of oil removal fluid is too low, it can constitute incomplete oil removal.
Pickling
In the production process, there is a nitric acid pickling process after alkali washing, which aims to remove the residual substances after alkali washing and neutralize the residual alkali liquor. The mass concentration of nitric acid solution is 5% ~ 10%. When preparing, carefully pour nitric acid into water and mix well. In the pickling process, we should often pay attention to the concentration analysis of the solution and make up in time.
Coarsening
Coarsening is to form a sand mesh structure with required roughness. Coarsening can not only improve the affinity of the surface of the aluminum plate base for water, but also improve the moisture content of the surface of the plate base, so as to avoid dirt on the layout; The coarsened appearance can also improve the adhesion between the plate and the photosensitive agent, and then improve the printing resistance of the printing plate.
After coarsening, the sand mesh is composed of numerous convex peaks and concave valleys. Different sand mesh structures have a great impact on the adhesion of water retaining and light sensitive layer and the application of PS version. The production top is characterized by the characteristic parameters of the sand mesh rough section profile curve made by the appearance roughness tester.