The so-called "orange peel" is actually a surface defect similar in appearance to orange peel, and it is a slight regular convex and concave pattern seen under a magnifying glass. The reasons are:
(1) The solidification speed of the powder is too fast, the self-leveling property is poor, or the solidification temperature is low, and the melt fluidity is poor;
(2) When the parts are sprayed, the powder from the spray gun is intermittent, the parts are suddenly far and near, or the parts are electrostatically shielded, which causes the thickness of the powder layer on the surface of the parts to be different, the coating film is too thin, and the surface of the coating film is muscle-like wrinkles; the coating film Too thick, the coating is striped orange peel;
(3) When spraying, the powder atomization is not good;
(4) Mixed powders of the same color from different manufacturers. Due to the different formulations and selection of raw materials of the same color powder from different manufacturers, the speed and surface tension of the powder during melt leveling are different, resulting in orange peel or shrinkage;
(5) The defects of powder coatings are mainly: poor dispersion of powder coatings, that is, poor dispersion between pigments, resins and additives, resulting in inconsistent leveling speed and surface tension of powder coatings during melt leveling , forming orange peel or even shrinkage; the fineness of the coating is not enough (mainly the problem of the pigment), there are some large particles, which will produce orange peel or shrinkage after curing; the manufacturing raw materials of powder coatings (resin, leveling agent, curing agent, etc. Additives) Improper selection or low grade or multiple products of one material may cause orange peel and shrinkage cavity after powder solidification.
