powdery compounds that are used to coat surfaces by means of spraying. The basic components of powder paints are film-forming materials, pigments, and fillers; other components may be plasticizers, stabilizers, hardeners, and surfactants. Film-forming materials for powder paints may include such oligomers as epoxy and polyester resins and various polymers, such as polyvinyl butyral, polyvinyl chloride, polyacrylates, polyamides, polyethylene, polyfluoroethylene resin, pentaplast, cellulose esters, and polyurethanes.
Powder paints are obtained by mixing dry powdery components or by homogenizing melts of these components with resulting pulverization. The most important properties of powder paints are particle size (usually 50–500 microns), polydispersion, ability to flow freely, easy application, and film formation. Powder paint coatings are formed at elevated or ordinary temperatures. In the former case, the article coated with powder paint is heated to a temperature above the melting point of the powder, while in the latter case the article is left standing in a vapor or in a solvent in aerosol form.
The advantages of powder paints include convenience of storage and transportation and ease and economy of application. The absence of solvents in such paints makes them nontoxic and reduces their flammability. Powder paints are used for the same purposes as ordinary liquid paints; sometimes powder paint coatings are applied instead of metallic or silicate coatings.
REFERENCESIakovlev, A. D., V. F. Zdor, and V. I. Kaplan. Poroshkovye polimernye materialy i pokrytiia na ikh osnove. Leningrad, 1971.
A. D. IAKOVLEV