A process for coating articles

Articles e.g. steel or glass panels, are coated by heating the article to between 275 and 305 DEG C., and dipping into a fluidised bed of polypivalolactone particles after which the article having a layer of polypivalolactone adhering to its surface is removed. The particles may contain one or more heat stabilizers, nucleating agents, pigments, fillers and other additives, examples of which are given. The term "polypivalolactone" is defined as meaning a thermoplastic resin which consists substantially of a linear polyester having recurring units of formula -O-CH2-C(CH3)2-C(O)- and may consist of a homo or copolymer of pivalolactone, or polymer blends thereof with for example polyamides, e.g. nylon, polyesters e.g. polyethylene terephthalate, polyvinyl chloride, polyvinyl butyral, polyepoxides, polyolefins e.g. polypropylene, or chlorinated polyether resins. The fluidizing gas may be heated up to about 10 DEG C below the sintering point of the particles e.g. below about 190 DEG C for pivalolactone homopolymer. The fluidizing gas may be a non-oxidizing gas e.g. nitrogen or carbon dioxide. The removed article is maintained at between 230 and 300 DEG C for a sufficient time to obtain a continuous well melted coating. The polypivalolactone particle size may be substantially from 25 to 1000 microns. The surface of the article may be cleaned and roughened e.g. by sand or metal grit blasting, acid-etching or solvent treatment, prior to coating and parts not to be coated may be masked with for example silicon resin. The coating process may be repeated to build up a thicker coating upon the article.