Mikuni Color Ltd.

Seiko Epson Corporation

Kazumi Adachi

Naoki Okamoto

Minoru Waki

Kiyohiko Takemoto

Hidehiko Komatsu

Michinari Tsukahara

Shuichi Yamaguchi

Hiroto Nakamura

Kazuaki Watanabe

Hideo Yamazaki

Naoki Tanaka

An ink composition is provided which can realize printing with excellent fixation even on a coated paper having a smooth surface. Further, an ink composition is also provided which, when used in ink jet printing, causes neither clogging nor creation of a precipitate. A copolymer of butyl acrylate, methyl methacrylate, and acrylic acid is added to an ink composition.

Ink composition capable of realizing print with improved fixation

An agglomerated pigment comprises (1) an organic pigment compound, (2) either a sulfonated organic pigment compound obtained by incorporating at least one sulfonic group into the organic pigment compound or a sulfonated organic pigment derivative obtained by incorporating at least one sulfonic group into a derivative of the organic pigment compound, (3) univalent inorganic counter ions bonded to sulfonic groups of component (2), and (4) bivalent or higher inorganic counter ions which are bonded to sulfonic groups of component (2) and wherein each such group has an at least univalent positive charge, the surface of the agglomerated organic pigment as a whole being positively charged. An aqueous pigment dispersion and a water-based ink composition both having excellent storage stability, an agglomerated pigment for use as a raw material for the dispersion, and a process for producing the pigment are provided.

Agglomerated pigment, process for producing the same, aqueous pigment

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Hyogo, Japan

Kazumi Adachi