Powder coating materials are unique among all present-day compliance coatings. They are “dry,” solid, essentially 100% film-forming coating materials, as opposed to the liquid materials used in high solids, water-reducible, radiation cure, and electrocoat technologies.
Powder coatings are, in fact, not paint until the coated item emerges from the curing or fusion oven. Prior to baking, powder coatings are finely pulverized plastic compositions, and consequently, most resins used in powder coatings are quite different from those used with liquid paints. Liquid paints require resins soluble or miscible with solvents and/or water, whereas powder coatings require resins that are solid materials. These solid resins must be solid at ambient, and reasonably elevated, storage temperatures, and must be capable of melting sharply to low viscosities to permit flow to a continuous coating film when heated.
In the early ’70s the number of solid resin systems available to powder coatings manufacturers was somewhat restricted and, consequently, there were limitations on their ability to meet the diverse needs of the finishing industry. However, the growth of powder coatings has been accompanied by a rapid technological expansion, resulting in many new resin systems and other compositional components. This has now made available a wide range of powder coatings that will meet, and often exceed, the properties of most present day solvent-based and water-based baking enamels.
Today, powder coatings are available to the industrial finisher in two major types, thermoplastics and thermosets. Like all other industrial surface coatings, powder coatings are individually formulated to meet the industrial user’s very specific finishing needs. This means matching the finisher’s house colors and film performance requirements, all within the particular restrictions of the finisher’s operation. New types with unique properties are constantly being developed. Consequently, as with the selection of any industrial finish, a close relationship must be developed between the user of the coating and the supplier so that these exacting requirements are thoroughly understood, and the correct type of finishing material is supplied.
For more information,please visit http://www.samaterials.com/406-thermal-spraying-material