Abstract
The use of a supercritical fluid (SCF), especially carbon dioxide, in place of conventional organic solvents for the spray application of coatings provides distinct advantages to both the applicator and formulator. VOCs and HAPs are significantly reduced or, in some cases, eliminated entirely as part of the reformulation process. Characteristics of the SCF spray process have demonstrated improved transfer efficiency and allow more rapid application of coatings providing sizable economic benefits to the applicator while meeting current environmental regulations. Despite being more environmentally friendly, the SCF-applied coatings usually show performance improvements including better appearance, corrosion protection, and chemical etch resistance compared to the conventional solvent-borne coatings they replace. This is believed to result from the superior, “decompressive” atomization which the use of a supercritical fluid produces. Several types of solvent-free coatings which cannot be applied by conventional methods have been successfully applied using the SCF spray process indicating that, with appropriate resin development, applicators will be able to use the system to meet regulations no matter how stringent they become in the future.
