What are the reasons for the color difference on the surface of PPGI PPGL color coated steel coil?
Paint, painting film thickness, viscosity, plate temperature, cooling water, curing oven, uneven or no stirring of paint will cause color difference on the surface of color coated galvanized/aluzinc steel roll.
1. Refers to the color difference (light color) of the paint in the same batch or in the bucket.
2. Paint pigments and fillers are different.
3. When changing to a new batch or new paint, it results in color difference from the feed port to the return port.
4. Features: It extends from the side of the feed port to the direction of the return port, and it is distributed in a strip shape and gradually widens.
2.Painting film thickness
1. It refers to the color difference caused by the different thickness of the painting film.
2. The viscosity of the coating and the pressure change between the coating rollers.
3. Refers to different color coated rollers or both sides of the same color coating roller.
4. There is no significant change, but there are a big difference between steel coils.
1. Refers to the color difference caused by low or high viscosity on paint.
2. The viscosity in the barrel is very different from the viscosity of the barrel paint.
3. After a few minutes of paint change, the color difference of the ribbon appears on the side of the feeding port.
4. This problem is the same as the previous film thickness variation. Essentially, a high or low viscosity will eventually cause a change in film thickness.
3. Plate temperature
1. The color difference are caused by too high or too low temperature of steel plate.
2. The furnace temperature setting is unreasonable and the feeding is wrong.
3. Phenomenon: The gloss of the layout is not high, and the MEK is unqualified.
4. There is no problem with the same panel, but different steel coils vary greatly.
5. Cooling water
1. Color difference are caused by water quality.
2. The water quality is not good, and the effect of the press roll is not good.
3. Phenomenon: The plate surface is black and the gloss is not high.
4. Features: surface dirt can be wiped off with cotton yarn.
6. Curing furnace
1. Refers to the color difference of both sides of the steel plate.
2. The temperature of the drive side and the operation side of the curing oven is not uniform.
3. Features: There is no obvious chromatic aberration in the longitudinal direction, and the chromatic aberration in the lateral direction is large (similar to the color difference in film thickness on both sides).
7. The paint is not evenly mixed or not stirred well.
1. It is distributed on the board in a strip shape.
2. Paint layering results in viscosity differences.
For more information about PPGI/PPGL color coated steel coil, you can contact WITOP STEEL.
Qingdao Witop Steel Co.,Ltd.