Reasons for anodizing
1. Principle of oxidative dyeing
The anodic oxide film is composed of a large number of hexagonal unit cells perpendicular to the metal surface, each unit cell has a film hole in the center, and has a strong adsorption force. When the oxidized aluminum profile is immersed in the dye solution, the dye molecules pass through. Diffusion enters the film pores of the oxide film, and forms covalent and ionic bonds that are difficult to separate with the oxide film. This bonding is reversible, and desorption can occur under certain conditions. Therefore, after dyeing, it must be subjected to sealing treatment to fix the dye in the film pores, and increase the corrosion resistance and wear resistance of the oxide film.
2. The influence of anodizing process on dyeing
In the whole process of oxidative dyeing, it is relatively common to cause poor dyeing due to the oxidation process. The uniformity of the film thickness and pores of the oxide film is the premise and basis for obtaining a uniform and consistent color during dyeing. In order to obtain a uniform and consistent oxide film, it is important to ensure sufficient circulation, cooling, and good electrical conductivity. In addition, oxidation process stability.
Cause of staining
1. Washing before dyeing
After anodization, sulfuric acid solution remains in the pores of the oxide film, so the aluminum profile
must be thoroughly cleaned before dyeing. Avoid bringing impurity ions into the dyeing tank, especially phosphate ions, fluoride ions, etc. It is necessary to set up pure water cleaning before the dyeing tank, and to monitor the water quality.
2. Preparation of dyeing tank
Most of the dyes used in dyeing are organic dyes, which are prone to mildew.
3. Dyeing process control
Reasons for sealing holes
Sealing treatment is an indispensable part of anodizing. After oxidative dyeing, only sealing treatment can ensure the original color of the dyed film. There are many kinds of sealing processes, such as steam sealing, hot water sealing, medium temperature sealing. Holes are all good choices, and some dyes can also choose cold sealing technology. After sealing, the color may be slightly lighter than before sealing due to fading, but just pay a little attention.