Fujitsu Isotec Limited

Hiroyuki Ohyama

Masaru Sugie

Chiaki Sekioka

Kohei Kiyota

A water-based pigment-type ink containing at least water, a pigment and a dispersant, the pigment particles having an average particle diameter of not larger than 0.1 .mu.m, the weight ratio of the pigment to the dispersant being from 1.2 to 5. The water-based pigment-type ink exhibits more excellent color tone and chroma, by adding the fluorescent pigment in an amount of from 0.1% by weight to 3% by weight with respect to the amount of the ink. Furthermore, the water-based pigment-type ink comprises at least a pigment, a high-molecular dispersant, a surfactant and water, the pigment particles having an average particle diameter of not larger than 80 nm, a maximum particle diameter not being larger than 0.1 .mu.m, the high-molecular dispersant being added in an amount of from 3% by weight to 20% by weight with respect to the amount of the ink, and the surfactant being added in an amount of from 2% by weight to 4% by weight with respect to the amount of the ink.

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Inagi, Japan

Hiroyuki Ohyama