Date on Master's Thesis/Doctoral Dissertation
Collins, Dermot Joseph
In a printing ink plant, phthalocyanine (Pc) aqueous slurries are produced by grinding the Pc pigment in water using a media mill. Mostly, dispersions of Pc in water are used in heat-set printing inks to make the color phthalo blue. Typically, Pc slurries are 40-50% solids and ground with steel media (spherical beads) to produce a stabilized dispersion with 99.9 percent of all solid particles less than 0.5 microns in size. Vertical media mills have been the industry norm; however, in producing submicron particle sizes, the efficiency is less than that of newer horizontal media mills that feature high internal flow and multiple pass grinding (Savastano, 2004). The goal of this experimental study was to determine the optimum operating conditions for a small industrial unit that incorporates newer technology. The first objective was to demonstrate in the laboratory the efficacy of grinding aqueous slurries of Pc using a horizontal peg media mill whose grinding chamber has a small length to width ratio. This was accomplished using a 0.55 L Labstar Zeta mill, producing a satisfactory dispersion. A second objective in the laboratory was to optimize operating conditions (shot loading, agitator speed, and pump speed) in order to minimize the grinding time to produce acceptable product. The optimized conditions were: shot loading level of 85%; agitator speed of 3000 RPM; and pump speed of 200 RPM yielding a run time of 1.33 hours (80 minutes). The success of this project enabled an industrial chemical company to quickly bring a new 25 L unit on stream to grind and disperse Pc in water. Efficient production of finished ink was accomplished using almost identical operating conditions.
McDowell, Robert Ian 1981-, "Particle size reduction of phthalocyanine blue pigment." (2006). Electronic Theses and Dissertations. Paper 946.