Riso Kagaku Corporation

Syotaro Kon

Hiroshi Hayashi

Toshihiro Endo

Kenji Shimomura

Tetsuo Hosoya

Masakatsu Arai

Teruaki Okawa

In a non-aqueous pigment ink that includes pigment, a non-aqueous solvent, and a non-aqueous resin that functions to disperse pigment dissolved in the non-aqueous solvent, the non-aqueous solvent includes a hydrocarbon based non polar solvent at 50% by mass or more with respect to the total amount of solvent. The non-aqueous resin is an acrylic polymer having a comb shaped structure, in which alkyl groups having carbon numbers from 8 to 18 and urethane groups form side chains on a (meth)acrylate main chain. The acrylic polymer is a copolymer of an alkyl(meth)acrylate (A) having alkyl groups with a carbon number from 8 to 18, a reactive (meth)acrylate (B) having functional groups that react with amino groups, and a monomer (C) having &#x3b2;-diketone groups or &#x3b2;-keto acid ester groups, into which the urethane groups are introduced by reactions between the functional groups that react with amino groups, amino alcohol, and a multivalent isocyanate compound. The mass ratio between the copolymer moiety and the urethane group moiety in the acrylic polymer is from 80:20 to 99:1.

Non-aqueous pigment ink

A non-aqueous inkjet ink comprises silica and Brilliant Carmine 6B. A peak area obtained at the time of measurement of an organic acid quantity of a water extract of Brilliant Carmine 6B by use of a capillary electrophoresis apparatus is selected within the range of 50 to 300 mABU*sec.

Non-aqueous inkjet ink

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Ibaraki, Japan

Syotaro Kon