Toyo Ink Manufacturing Company

Toyo Ink Mfg. Co., Ltd.

Tsukasa Iguchi

Toshiyuki Uemura

Akimitsu Mochizuki

Sunao Satake

Yasuharu Iida

Hisashi Uraki

Mikiya Kato

There is disclosed a self-dispersible aqueous pigment dispersion and preparing method thereof, the dispersion comprising an aqueous solution, particles of a pigment and a water-soluble pigment derivative, said particles being dispersed in the aqueous pigment dispersion in a concentration within the range from 2 to 25 wt. % based on the amount of the aqueous pigment dispersion, wherein a part of the water-soluble pigment derivative is adsorbed on the surface of the particles of the pigment to form dispersed particles comprising the particles of the pigment adsorbed by said part of the pigment derivative, and the remaining parts of the water-soluble pigment derivative are free in the dispersion without being adsorbed on the surface of the pigment in a concentration less than the critical flocculation concentration on which flocculation is initiated on said particles of the pigment dispersed under said concentration. The pigment dispersion has high dispersibility in an aqueous system and excellent dispersion stability over time, and is applicable to an inkjet recording liquid, which provides excellent light-resistance, water-resistance and hue of printed image, and simultaneously reveals excellent discharge stability at the nozzles of ink-jet printer.

Self-dispersible aqueous pigment dispersion

A surface-treated organic pigment excellent in initial dispersibility and long-term dispersion stability in water and an organic solvent and free from the coagulation of pigment particles, obtained by reacting a sulfonating agent with an organic pigment dispersed in a solvent in which the organic pigment is insoluble or sparingly soluble, and thereby introducing a sulfonic acid group to the surface of each particle of the organic pigment.

Surface-treated organic pigment and process for the production thereof

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Tokyo, Japan

Tsukasa Iguchi