Preparation and properties of hydrophilic PR 57:1 with inorganic core/solid solution shell

A series of modified pigment red 57:1(P. R. 57:1) were prepared by forming a pigment solid solution in-situ on the surface of different inorganic cores. Influence of core type (silica gel, kaolin, sepiolite and silica micropowder) and core size (silica micropowder 850 mesh and 1250 mesh) on the properties of the modified pigments were investigated, and it was found that the pigment with silica gel as core had the best performance. The schaffer's salt, tobias acid and sulpho toluic acid were used as the second components, and DSC and XRD analysis result showed that they all formed a pigment solid solution on the surface of the inorganic cores. When the amount of sulpho tobias acid was 3% and the inorganic core was silica gel, the modified pigment had the smallest particle size, narrowest particle size distribution and showed blue-red color, which was similar to the commercial available pigment sample C. P. R. 57:1. Moreover, the contact angle, Zeta potential analysis results and water-based ink test results showed that the hydophilicity of the modified pigments was obviously improved.