Patent ID: 7361700

Claim:
A method for producing a colorant comprising: contacting a dispersion of a powdery coloring matter substance in deionized water with an anion exchange resin and/or a cation exchange resin to subject the dispersion to ion exchanging until an electrical conductivity of the dispersion reaches 25 μS/cm or lower, thereby obtaining a purified coloring matter substance; contacting with an anion exchange resin and/or a cation exchange resin an aqueous solution or organic solvent solution of a binder resin prepared so that a carboxyl group concentration or a sum of a carboxyl group concentration and a hydroxyl group concentration is 0.001 mol/ml or higher, to obtain a purified binder resin solution; kneading the purified coloring matter substance and the purified binder resin solution to obtain a liquid colorant precursor; and contacting the liquid colorant precursor with an anion exchange resin and/or a cation exchange resin.