In the coating process of 2C1B metallic flash color topcoat, the basecoat and finish paint are "wet-on-wet" processes, that is, both are dried together, and the drying speed and degree of the basecoat are the same as those of the topcoat. The appearance quality of the coating film has a great influence.
The base paint is generally one-component, and the drying (drying) process of the coating film is the volatilization process of the solvent. In order to prevent uneven color depth base paint film is required to be dried quickly in a short time (that is, in the coating film). The solvent is basically evaporated). If the drying is slow (solvent volatilization is slow), the aluminum powder aligned in parallel may flow, or when the solvent is not volatilized before the varnish, it may be miscible, causing the aluminum powder to float, which directly affects the coating of the shiny color topcoat. appearance of the membrane. The drying speed of the primer depends on the ambient temperature in the drying room, the wind speed and the concentration of solvent vapor, the volatilization speed of the solvent, etc. Please pay special attention: the solvent needs to use a low boiling point solvent with a fast evaporation rate. In order to speed up the drying of the base paint, some body painting lines are equipped with a hot air blowing device in the drying section.
Typical today's drying specifications for iridescent basecoats are as follows.
Drying specification for organic solvent-based base paint: at room temperature, wind speed 0.7m/s, more than 3min. Specifications for drying after varnishing : above 40~80°C to prevent air bubbles.
Drying specifications for water-based base paint: 2 minutes at room temperature, 5 minutes at 70°C, and cooling the body to 30°C.