An improvement of color electrophoretic paint via ultrafine modified pigment paste

摘要

The ultrafine paste used in electrophoretic paint was prepared via ultrasonic method with pigment yellow 83 (P.Y.83), octadecyl dimethyl benzyl ammonium chloride, and deionized water. The average particle size of the ultrafine paste was only 196 run and zeta potential was 30 mV with ultrasound for 30 min and 2 wt% cationic dispersant. The conductivity of the paint was improved as the cationic dispersant increased. Centrifugal stability of the paint with ultrafine paste reached the maximum at 2wt.% cationic dispersant. Compared with the performances of cathodic electrophoretic paint with the ultrafine yellow paste, the anodic film was smooth, uniform, and neat with 0.5 wt.% cationic dispersant in the ultrafine yellow paste. Deposited amount of the anodic film was 27 g/m~2, which was higher than the cathodic film. The curing property, adhesion, and chemical resistance of the cathodic film were better than the anodic film. Properties of five color cathodic paints (blue, yellow, red, black, and green) were discussed and were compared with the film of electrophoretic paint containing commercial pastes. Except the green film, the blue, yellow, red, and black films were smooth, fine, and uniform, and also provided good L-effect. The deposited amount of these films with excellent adhesive force was about 14-19 g/m~2. The electrophoretic paints containing modified pigment pastes and commercial pigment pastes present good adhesion and chemical resistance.