ABSTRACT
The most common polymers used in powder coatings are polyester, epoxy, polyurethane, polyester– epoxy mix (hybrid), and acrylics. The most important thermoplastic powder coatings are vinyls, nylons, and polyolefins. The thermosetting powders dominate the market, and polyesters, epoxies, and polyester– epoxy hybrids are the dominating thermosetting powders. The production of the powder for powder coatings has more in common with the production of plastics than with the production of solvent or waterborne coatings. Four Application techniques of the powder are electrostatic spraying, fluidized bed, flocking gun, and flame spraying. Two types of powder application guns are used, with different principles for charging the powder: tribo and corona. Powder coating application line process includes: (1) racking or hanging; (2) Pretreatment; (3) Powder application; (4) Film formation and curing; and (5) Offloading, inspection, and packing. Quality control of powder coatings is basically done by the same methods as quality control of other organic coatings, for example, adhesion, chalking, and corrosion.
