The cleaning and degreasing treatment ofcolor-coated sheet is mainly to use the dissolution, saponification, emulsification, moisture, penetration and mechanical functions of industrial chemical cleaning solutions to remove the oil stains and foreign particles on the surface of the substrate. Most of the chemical cleaning fluids currently used in production lines are composed of compounding agents, surfactants, sodium hydroxide, potassium hydroxide, polyphosphate, etc.
The degreasing effect of prepainted steel sheet cleaning mainly depends on the concentration of cleaning time. Be careful of the actual concentration and temperature of the cleaning fluid during the entire cleaning process. The concentration of the cleaning solution is low, and the oil on the surface of the substrate is not clean, resulting in insufficient treatment of the trailing edge coating, which affects the quality of the coating.
When the concentration value is too high, the zinc and aluminum in the galvanized steel sheet belong to amphoteric metal materials. The appearance of the zinc and aluminum layers in the hot alkali aqueous solution simply constitutes octanoate, which causes serious corrosion and harms the subsequent organic chemistry Coating effect. Organic chemical cleaners generally have surfactants, and the temperature difference of various surfactants is large.
During the cleaning process of the prepainted galvanized steel sheet, the temperature is too high, the reliability of the surfactant is reduced, the temperature of the oil removal of the cleaning fluid is too low, the saponification reaction rate cannot completely remove the oil, and a large amount of foam plastic is harmful to cleaning. In addition, high-temperature cleaning fluid will accelerate the corrosion of zinc aluminum layer.
