Supercritical fluid-assisted dispersion of ultra-fine pigment red 177 particles with blended dispersants

A series of experiments was conducted to investigate the dispersion of 1 wt.% of pigment red 177 particles in propylene glycol monomethyl ether acetate (PGMEA). It was found that 40 wt.% of Hypermer PS3 dispersant could provide better dispersion and could stabilize the pigment particles in PGMEA at ambient condition. With the aid of supercritical carbon dioxide (CO2), additional 1 wt.% of CO2-philic dispersant, Zonyl FSO-100, could further enhance the dispersion. Holding the mixtures in dispersion chamber at higher temperatures and pressures for a sufficient period of time was also favorable to improve the dispersion. The size of the dispersed particles appeared to have a correlation with the phase behavior of the mixtures in the dispersion chamber. The preferable operating conditions are at 348.2 K and 20 MPa, and 20 min of holding time was long enough before rapidly releasing chamberʹs pressure. Under the recommended operating conditions, the mean sizes of the dispersoids could be as small as 148 nm, which met the required range of 100–200 nm in industrial applications. The TEM images have proven that the supercritical carbon dioxide-assisted dispersion method could efficiently disperse the pigment particles in PGMEA.