| abstract |
A method of producing a pigment dispersion composition includes causing (I) a pigment that includes a surface acidic group to come in contact with (II) a basic compound that includes two or more amino groups selected from a primary amino group and a secondary amino group in its molecule in an aqueous medium to prepare a pigment that includes an unreacted surface amino group, causing the pigment to come in contact with (III) a polyisocyanate polyurethane resin that includes two or more isocyanate end groups so that the pigment and the polyisocyanate polyurethane resin are bonded via a urea bond to prepare a dispersion of (A) a polyurethane resin-bonded pigment, and heating the dispersion of the polyurethane resin-bonded pigment (A) at 40 to 100 DEG C for 1 to 30 days. The method can easily produce a pigment dispersion composition that exhibits excellent image density, dispersibility, and storage stability, has high resolubility, and provides an ink film that exhibits excellent marker resistance and scratch resistance. |