But what does the term wax really mean? It does refer to a large range of both natural and synthetic materials derived from fatty acid esters or polymers. Just a word of caution, though, that the chemical composition of these materials alone won’t determine a wax. In order for the emulsion to have a substantial effect on the critical properties of specialty powder coating, the additives have to be present in proper amounts and must migrate to the surface. This migration can be done in different mechanisms, including the two major ones clearly identified below.
Ball Bearing Wax Migration Mechanism
Under this mechanism, the solid particles of wax do migrate to the surface individually and serve as a physical barrier by protruding above the specialty coating. This prevents another surface to come into contact with the coating surface. The waxes used in this mechanism include the hard and high-melting-point waxes such as the high-density polyethylene and PTFE. What affects the degree of impact are the extent of protrusion and the particle density of the wax. It is only when the wax has migrated to the surface when it has the ability to modify and impart the required effects. This is the main reason why the specialty powder coating emulsion process requires surface conditioner additives.
Blooming Wax Migration Mechanism
As the name implies, wax particles that molted bloom to the surface. When they recrystallize, they form a thin wax-enriched surface layer as the coating cools down. This migration mechanism can be enhanced with more incompatibilities between the coating and the wax. Generally, the blooming becomes more predominant if the wax is softer or has a low melting point.