Views: 65 Author: Site Editor Publish Time: 2018-12-14 Origin: Site
In electrostatic powder coating, the cause of colour aberration of the coating film is caused by both side powder coating and powder coating process control.
Considering the powder coating itself, the general powder coating production plant is formulated according to the user's requirements, according to the user's color card, sample, physical or color card, and according to the baking temperature and time provided by the user. When both conditions are the same, the color of the coating film is not good and there is a large color difference.
If colour aberration occurs in powder coating, one of the possible reasons is that the heat resistance of the raw materials selected in the formulation design, such as pigments, matting curing agents, etc., is not ideal; in addition, the curing conditions of the powder coating factory are There is a certain gap between the baking conditions of the powder coating factory when it is toned.
In terms of powder coating, the following factors will affect the color difference of the powder coating film.
In the powder coating process, when the thickness of the coating film is not uniform, the color difference between the thin portion and the thick portion of the coating film is remarkable, especially when the hiding power of the powder coating is not too strong, between the coating film spray and the thick coating film. The color difference is more obvious. In order to minimize the chromatic aberration of the coating film, in the powder coating, a certain degree of coating film thickness must be ensured, and the coating film thickness should be uniform.
From the powder coating process, the temperature control sensitivity of the curing oven is poor, and the coating film is liable to cause colour aberration when the temperature distribution is uneven. In order to reduce the difference during baking and curing, the temperature control sensitivity of the baking furnace is required to be high, and the temperature distribution is uniform. From the uniformity of the temperature distribution, the color difference of the coating film caused by the hot air furnace is smaller than that of the infrared heating furnace.
In the baking process of powder coating, the baking time also has a significant influence on the color difference of the coating film. In particular, the thickness of the material to be coated is different, and the heat capacity is different. If the objects to be coated with different thicknesses are hung in the same baking oven for baking and curing, the effective baking after the object reaches the set temperature The time is short, so that different material thicknesses are also prone to chromatic aberration between the objects to be coated. Therefore, when the powder is coated with different materials, thicknesses, shapes and sizes, it should be classified according to the material, thickness, shape and size of the object to be coated, and then set to different baking times for baking. , can reduce the chromatic aberration of the film.
In powder coating, when changing the color of the paint, if the powder supply device, spray gun, dusting chamber and powder coating recovery system are not cleaned, it is most likely to cause the color of the powder coating used in the front to contaminate the color of the powder coating used later. . In particular, when the color difference between the varieties of the replacement paint is large, the color difference of the coating film is more likely to occur. Therefore, in changing the color of the paint, it is necessary to thoroughly clean the powder coating and recycling system of the powder coating in order to reduce or avoid the chromatic aberration of the coating film.