The sagging phenomenon of the color coating production line generally occurs in the vertical roller coating process. After passing through the vertical roller coating machine, the coating on the front and rear ends of the steel strip appears to hang down, that is, the entire coating falls and moves downward, forming a paint coating. The thickness of the film is uneven, the light ones are like beaded tears, and the severe ones are like hanging curtains.
cause:
(1) After coating and the viscosity of the paint is too low, the paint flows downward due to its own weight;
(2) The thinner volatilizes slowly, the air is not circulated, the solvent content in the air in the roller coating room is too high or the ambient temperature is too low;
(3) Improper surface treatment before coating or oil and water pollution on the surface of the steel strip entering the roller coating machine, resulting in poor adhesion.
Method of exclusion:
(1) Choose an appropriate diluent to increase the viscosity of the coating on the machine;
(2) The coating should not be too thick, and it is better to test the anti-sagging performance of the coating before putting it on the machine;
(3) Increase the air exchange rate in the roller coating room, and keep the ambient temperature of the roller coating room above 10°C. When the temperature is too low, you can use the paint to keep warm or use a thinner with a volatile block;
(4) Choose a good substrate and do a good job in the pretreatment of the substrate to prevent the adhesion of oil and water and ensure the adhesion of the coating.
