The curing temperature of the electrophoretic coating film is determined by the curing agent (crosslinking agent) and the crosslinking characteristics of the resin itself. In the electrophoretic coating process, more than two solvents are often used, one of which is a low boiling point solvent (80-90°C), and the other is a high boiling point solvent (160-180°C). The solvent acts as a solubilizing agent and at the same time acts as a leveling agent for the coating film.
Therefore, for the drying of acrylic and polyurethane electrophoretic coatings (related instruments: drying time Tester), two temperature stages are often used.
(1) Pre-baking
The temperature is 80-100 ℃, pre-bake for 10min-15min, remove the moisture and low boiling point solvent in the coating film, and make the surface of the coating film smooth. At this time, the coating film is not cured, and the workpieces cannot collide with each other or touch with hands.
(2) The curing temperature is controlled at 150-180°C, and baked for 20-30 minutes (related testing equipment: oven), so that the coating film is basically cured. The lower the temperature, the longer the baking time; the higher the temperature, the shorter the baking time. Different types of paint electrophoretic coating, the operating conditions will be different, as listed in the table.
As mentioned in the table, the conductivity is 250-550 in acrylic cathodic paint, and the pH value needs to reach 3.0-5.0.
