A supercritical fluid-based coating technology. 2: Solubility considerations

Solubility measurements of candidate coating materials have been performed in supercritical (SC) CO2 so as to select appropriate coating materials for implementation of a solvent-free coating process previously described. Solubility of lipidic compounds such as waxes (paraffin, beeswax, Carnauba wax), pure triglycerides (tricaprin, trimyristin, tripalmitin, tristearin) and mixture of glycerides and fatty acid esters (Gelucire(R)) in SC CO2 were evaluated in a static mode under different temperature and pressure conditions, ranging from 13-52degreesC and from 50-220 bar, whether the CO2 was in its liquid or SC state. It was shown that the compounds which are mixtures of various components give rise to a selective extraction of the lower melting point components, as evidenced from thermal analysis of soluble and insoluble fractions of the coating materials.