Riso Kagaku Corporation

Shin-ichiro Shimura

Shunsuke Uozumi

Sayako Arai

In an inkjet printing system using an emulsion ink, it is aimed that printing density is improved particularly for a normal paper. An inkjet printing method is provided, in which printing is performed by ejecting one of first and second inks onto a printing medium, and then successively ejecting the other ink so as to overlay it in the one ink, wherein the first ink is a water-in-oil (W/O) emulsion ink comprising the coloring material which is provided with an acidic group on a surface in the water phase, and the second ink is a water-in-oil (W/O) emulsion ink comprising a polyvalent metal salt in the water phase. Preferable acidic group is carboxylic group, sulfuric acid group and phosphoric group. Preferable polyvalent metal salt is a salt composed of metal ions such as Ca, Cu, Ni, Mg, Zn, Ba, Al, Feand Cr.

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Tokyo, Japan

Shin-ichiro Shimura