Smooth thin film powder coatings

摘要

A coating powder consisting essentially of generally spherical, preferably cellular, particles ranging in size from less than 2 to 40 mu m, 75% of whose volume consist of particles of from 2 to 20 mu m in size, is provided by dissolving the components of the coating powder in a supercritical fluid without the aid of a surfactant and spraying the solution into a zone whose pressure is less than that of the fluid. A very smooth continuous film of a cured thermosettable coating powder is achieved even when the film thickness is less than 25.4 mu m (1 mil), e.g. from 5 mu m (about 0.2 mil) and greater. The advantages of powder coatings may now be realised fully in the automobile and can industries.