Properties of a composite pigment of C.I. pigment red 177 prepared via a solid-state ball milling method

A composite pigment of C. I. pigment red 177 (P. R. 177) with a core-shell structure was prepared via a solid-state ball milling method. The sepiolite was firstly acidified and used as the inorganic core. Effect of time and temperature on the particle size of acidified sepiolite was studied. P. R. 177 and the chosen acidified sepiolite were then mixed in a ball milling jar to prepare the composite pigment. When the sepiolite content was 20% (accounting for the weight of the pigment), the optical properties of the composite pigment reached the level of the commercial P. R. 177 and the coloring force was 113.38%. FT-IR, SEM and TEM analysis showed that sepiolite was coated with P. R. 177 and formed the core-shell structure while sepiolite was not completely coated by pigment from XRD measurement. The melting enthalpy obtained from DSC suggested that mechanical energy could be transformed into chemical bonding energy through the ball milling method and the chemical bonding was further confirmed with IR spectra. Performance tests showed that the prepared composite pigment has a greater water dispersibility and a better light fastness compared with that of commercial P. R. 177 while they have almost the same ethanol resistance level.