Four reasons for anodizing dyeing

1. Washing before dyeing

After anodizing, sulfuric acid solution remains in the pores of the oxide film. Therefore, the aluminum products must be thoroughly cleaned before dyeing. Avoid bringing impurity ions to the dyeing tank, especially phosphate ions, fluoride ions, etc. It is very necessary to set up pure water to clean before the dyeing tank, and to monitor the water quality.

2. Dyeing tank preparation

Among the dyes used in dyeing, most of them are organic dyes, and organic dyes are prone to mold. In order to effectively prevent the tank liquid from becoming moldy, the tank body can be disinfected with bleaching powder, phenol and other drugs before preparing the tank liquid. When preparing the bath solution, adding an anti-mold agent can effectively prolong the use time of the dyeing solution. After the tank solution is prepared, it must be stored for several hours before it can be put into use. In order to ensure the stability of the pH value, acetic acid-sodium acetate slow can be added.

3. Dyeing process control

(1) temperature

In the 　　 dyeing process, the dyeing rate increases with the increase of temperature. Therefore, the time required to dye a certain depth of color decreases with the increase of temperature. At the same time, if the bath temperature rises, the synchronous sealing will also speed up. If the temperature is too high, the synchronous sealing will be too fast, and the dye molecules will not be adsorbed in the membrane pores in sufficient quantity, and the accumulation of the dye will be caused by the membrane pores of the oxide film. Closed and stopped, unable to reach the required depth, and dyeing at relatively low temperature can dye deeper colors, but the corresponding time is longer. Therefore, according to different color requirements, the dyeing temperature can be adjusted appropriately to avoid the dyeing time. Too long or too short.

(2) Dye concentration

According to the law of adsorption, under certain working conditions, the amount of dye adsorbed on the anodic oxide film increases with the increase of the dye concentration. However, this rule is only applicable when the oxide film itself has adsorption capacity. For colors of different depths, the dye concentration should also be adjusted accordingly. When preparing the bath solution, prepare a solution with a lower concentration as much as possible. As the production progresses, the dye is continuously consumed, and the consumed part should be replenished continuously. A small amount many times. If the concentration of the dye is determined, the influence of impurity ions should be considered. The actual effective concentration may be quite different from the detection. Therefore, the actual dyeing power of the dyeing tank should be compared and tested regularly.

In order to ensure stable dyeing power, after a period of production, part of the bath can be replaced.

(3) time

Same as electrolytic coloring, when other conditions remain unchanged, the color gradually deepens with time. Generally, when the oxidation conditions are determined, the concentration and temperature of the dyeing solution are determined. We only have to adjust the dyeing time to obtain the color depth required by the customer. If the dyeing time is too short, the required color can be obtained. There are two disadvantages. One is that the color is too fast, and it is not easy to obtain a uniform color; The color is too fast, and the color obtained is not weather-resistant enough. The dyeing time is too long, or the required color depth cannot be obtained no matter how long it is dyed. At this time, we have to consider whether the oxide film is too thin or the dye concentration is too low.

(4) ph value

Generally, the ph value is required to be 5-6. A stable ph value is very important for dyeing, especially for mixed dyes. Different ph values ​​may have different tones. To enhance the stability of the ph value, add it when preparing the bath Buffer solution is a feasible method. At the same time, it is necessary to strengthen the washing before dyeing to avoid bringing acidic substances.

4. Wash after dyeing

After dyeing, the aluminum products should be washed with water to remove the floating color attached to the surface of the aluminum products. At this time, pay attention to the water quality of the washing tank, because the combination of dye molecules and oxide film is reversible, when there are more impurity ions in the water , It will promote the separation of dye molecules from the oxide film and enter the water, at this time, it will show fading. This fading is often uneven, resulting in chromatic aberration on the same material.