Pigmentation of Vat Blue RS by ball milling in solvents

Pigmentation of Vat Blue RS by ball milling in the presence of organic solvents or water was carried out and the effects of ball milling time, characteristics of solvent used and two-step ball milling on the transformation of crystal phase and the resulting pigment properties were studied. Experimental results showed that the alpha-phase of C.I. Pigment Blue 60 can be obtained by ball milling 2 h in the presence of xylene and NaCl. The rate of transformation to the alpha-phase was improved with an increase in the proportion of aromatic solvents in the medium employed. By milling in an aqueous medium without organic solvents, the original pigment crystal phase was destroyed.