A pigment is synthesized in an aqueous medium and the pigment dispersion is purified by ultrafiltration or microfiltration. In particular, an aqueous pigment dispersion having a very small average particle size and a narrow particle size distribution may be prepared by the steps of (a) synthesizing a pigment in an aqueous medium and (b) removing an impurity such as a dissolved synthesis by-product or unreacted starting material through cross flow filtration using a membrane having an average pore diameter of from about 3 nanometers to about 3000 nanometers to produce a purified aqueous pigment dispersion.
A method for manufacturing a pigment dispersed liquid, comprising at least: Step A of introducing a hydrophilic dispersibility-imparting group directly and/or via another atomic group to the surface of pigment particles; Step B of dispersing the pigment obtained in Step A in an aqueous medium; and Step C of conducting refining treatment of the dispersed liquid obtained in Step B.
Liquid electrographic toner compositions are provided comprising a liquid carrier having a Kauri-Butanol number less than about 30 mL and a plurality of toner particles dispersed in the liquid carrier. The toner particles comprise polymeric binder and a pigment comprising a first ionic dye component ionically complexed with a second ionic dye component in a predetermined ratio to form an ionically complexed colorant compound exhibiting a predetermined color. The colorant compound has a molecular weight of less than about 5000 Daltons and is substantially free of metals that are not covalently bonded to the colorant compound. Toners comprising pigments comprising a ionic dye component and a second ionic dye component complexed to form ionically complexed compounds that together in a colorant composition exhibit a predetermined color are also provided. Methods of making and using these toners are disclosed.
