Finely divided pigments and coloring compositions

摘要

A finely divided pigment is formed of an aggregate of primary particles. A number of primary particles of not greater than 0.1 mu m in particle size is at least 95% of an entire number of the primary particles, and a number of primary particles of greater than 0.1 mu m in particle size is at most 5% of the entire number of the primary particles. The finely divided pigment can be produced by grinding a parent pigment (pre-division pigment) together with a water-soluble inorganic salt and a water-soluble organic solvent in a grinding machine at a temperature of from 30 to 90 DEG C for 2 to 6 hours under a load, and then removing the water-soluble inorganic salt and the water-soluble organic solvent. A coloring composition comprises a dispersing medium and the finely divided pigment dispersed in the dispersing medium. The coloring composition is, for example, an image recording agent for the ink-jet recording system, an image recording agent for the electronic printing or electrostatic recording system, or a coloring agent for forming color filter pixels.