To prepare a microencapsulated pigment desirable for the production of a pigment ink composition which can give a printed image being excellent in rubbing resistance, water resistance, and gloss and differing little in gloss between low and high density areas, and to obtain an ink composition containing the same.
The microencapsulated pigment is prepared by covering pigment particles having ionic groups on their surfaces with a capsule wall material based on a polymer comprising (1) repeating structural units derived from a polymerizable surfactant having an ionic group having a charge opposite to the charge of the ionic groups on the surface of the pigment, a hydrophobic group, and a polymerizable group and (2) repeating structural units derived from a hydrophobic monomer copolymerizable with the polymerizable surfactant, with the proviso that the starting material monomer used for the preparation of the polymer for capsule walls is selected so that the polymer obtained by the emulsion polymerization of the portion of the starting material monomer which remains after the polymerizable surfactant is excluded from the starting monomer may have a refractive index nd (20°C) of 1.50 or higher.
Takashi Watanabe
Yuko Ishikawa
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