The factors that affect the color difference of color coated plate are: coating, substrate, chemical coating treatment, film thickness, PMT and cooling water, etc. Specifically:
Becaue of the uneven mixing of the coating or the big difference of the viscosity of the coating in different barrels, the coating extends from one side of the feed port to the direction of the reflux port in the feed tray, and there
is a color difference band. In addition, changing the paint color, especially the two colors with large color contrast, will cause color difference due to unclean cleaning
II. Base plate
The color difference is also affected by the size of
the zinc flower on the substrate, and many small pits with different sizes will be formed at the grain boundary, which will affect the color difference on the surface of the substrate. For light color, the color difference is particularly obvious. It's
better to choose non zinc flower or small zinc flower substrate.
III. chemical coating treatment
Improper chemical coating process results in too thick chemical coating and insufficient plate temperature after drying. If the coating roller
body is damaged, yellow patches will be formed after drying, resulting in color difference of color coating plate, especially light color.
IV. film thickness
The stability of film thickness has great influence on the color difference of color
coated plate. The adjustment methods of film thickness mainly include: coating viscosity, adjusting the gap between the sticking roller and the coating roller, changing the roller speed of the coating roller and the sticking roller, adjusting the pressure
between the coating roller and the strip supporting roller, etc.
PMT indicates the peak temperature required for the strip steel when the coating is well cured. The stability of PMT has a great influence on the color difference of
color coated plate. The change of strip specification will result in the change of PMT, the high or low local temperature will affect the change of PMT, the uneven thickness of substrate will result in the change of PMT, and the change of temperature
in the furnace will also result in the change of PMT.
Vi. cooling water
Atomization cooling, cooling water is not replaced in time. When the volatiles of organic solvent in the furnace gas are cooled and condensed, the cooling water is brought
to the plate surface, and the color difference is caused on the plate surface after extrusion by the extrusion roller. In production, the cooling water should be kept overflowing properly, and the condensed volatiles should be removed in time to avoid
the color difference on the board.