Coated aluminum box is a kind of box made of coated aluminum profiles by aluminium doos manufacturers. There are two common ways to pretreat the surface of aluminum box: chromic acid passivation and phosphating. The main function of chromating is to prevent the corrosion of aluminum box surface and to improve the adhesion of aluminum box surface and other materials.
These pre-treatment methods have been widely used in the metal reprocessing industry, not just for the need of coating. For example, for spraying or painting, the surface of raw aluminum must be passivated and Phosphated. Otherwise, because the tension of the surface of raw aluminum is too small and easy to corrosion, it is difficult to re process or decorate its surface.
The aluminum box surface is coated after powder spraying, which is further treated on the basis of the original passivation or phosphating technology, so as to facilitate the coating. The reasons are as follows:
a. After the surface of aluminum box is treated, if it is not sprayed, its surface must be reprocessed in a short time, such as laminating, painting, etc., otherwise, the treated surface will fail (oxidized or corroded by air);
b. The visible surface of the aluminum box (such as the window slot after opening the window) is not spray treated, and the film covered part is obviously compared with the film uncoated part. The bare aluminum gives a low level of feeling. However, the overall cost of aluminum window is also increased by spraying treatment in the early stage, but this does not affect the use of high-end projects. It should be noted in technology that before powder spraying, chromate passivation or phosphating treatment should also be carried out on the surface of aluminum box to increase the adhesion fastness of spraying layer and base material. Because the coating glue used is polyurethane glue, it is suggested that the main raw material of powder spraying material on the surface should be polyester.
3. The aluminum box can be coated after the above method is pretreated. All subsequent steps and processes are the same as other substrate coating, including the plant and corresponding mechanical equipment. However, it should be noted that the adhesive used for aluminum alloy profile and UPVC is interlinked, which shall be tested by the customer or inquired about the supplier of the adhesive (according to the actual experience, the two are basically interlinked). The only difference between coating and UPVC profile is that as a metal, aluminum has fast heat dissipation. In the coating, pay attention to the temperature control (the required temperature is about 55 ℃), and the aluminum box cannot have sharp edges.