An object is to provide a nonaqueous inkjet ink composition offering excellent solid filling property and anti-mottling property, as well as excellent ink stability, discharge stability, and scratch resistance, even when printed at high speed on printing targets whose printing face is constituted by a polyvinyl chloride, ethylene-vinyl acetate-based copolymer, or other vinyl-based polymer, etc. As a solution, a nonaqueous inkjet ink composition is provided that contains acrylic-based resin, organic coloring pigment and/or carbon black, alumina, pigment dispersant, and organic solvent, wherein the organic solvent comprises propylene carbonate, diethylene glycol dialkyl ether, and dipropylene glycol alkyl ether acetate, and alumina is contained by 5 to 30 parts by mass relative to 100 parts by mass representing the total of organic coloring pigment and carbon black.

An object is to provide a nonaqueous inkjet ink composition offering excellent solid filling property and anti-mottling property, as well as excellent ink stability, discharge stability, and scratch resistance, even when printed at high speed on printing targets whose printing face is constituted by a polyvinyl chloride, ethylene-vinyl acetate-based copolymer, or other vinyl-based polymer, etc. As a solution, a nonaqueous inkjet ink composition is provided that contains acrylic-based resin, organic coloring pigment and/or carbon black, alumina, pigment dispersant, and organic solvent, wherein the organic solvent comprises propylene carbonate, diethylene glycol dialkyl ether, and dipropylene glycol alkyl ether acetate, and alumina is contained by 5 to 30 parts by mass relative to 100 parts by mass representing the total of organic coloring pigment and carbon black.

A radiation-curable ink jet composition contains a polymerizable compound, a white pigment, and inorganic particles different from the white pigment. The polymerizable compound includes a monofunctional polymerizable compound. The content of the monofunctional polymerizable compound is 80 mass % or more with respect to the total mass of the polymerizable compound contained in the radiation-curable ink jet composition.

A radiation-curable ink jet composition contains a polymerizable compound, a white pigment, and inorganic particles different from the white pigment. The polymerizable compound includes a monofunctional polymerizable compound. The content of the monofunctional polymerizable compound is 80 mass % or more with respect to the total mass of the polymerizable compound contained in the radiation-curable ink jet composition.

An ink jet recording method includes a treatment liquid attachment step, in which a treatment liquid is attached to a recording medium, and an ink attachment step, in which a water-based ink composition is attached to the recording medium. An ink jet recording apparatus includes a recording medium support and a heating mechanism that heats the recording medium support. The ink attachment step is carried out with the recording medium supported and heated by the recording medium support. In the ink attachment step, the recording medium is heated so that a surface thereof reaches a maximum temperature of 28.0° C. or more and 45.0° C. or less. The ratio between absorbances A and B (A/B) is 0.5 or more and 0.95 or less, where absorbance A is that of a 0.1% by mass mixture of the water-based ink composition in the treatment liquid, and absorbance B is that of a 0.1% by mass mixture of the water-based ink composition in purified water. The recording medium support has a flat support surface for supporting the recording medium.

An ink set includes a first ink containing the compound represented by formula (y-1) or its salt, a second ink containing one or two or more of the compound represented by formula (m-1) or its salt, the compound represented by formula (m-2) or its salt, a compound represented by formula (m-3) or its salt, and the compound represented by formula (m-4) or its salt, and a third ink containing one or two or more of a compound represented by formula (c-1) or its salt, the compound represented by formula (c-2) or its salt, the compound represented by formula (c-3) or its salt, a compound represented by formula (c-4) or its salt, and the compound represented by formula (c-5) or its salt. ##STR00001##

An ink set includes a first ink containing the compound represented by formula (y-1) or its salt, a second ink containing one or two or more of the compound represented by formula (m-1) or its salt, the compound represented by formula (m-2) or its salt, a compound represented by formula (m-3) or its salt, and the compound represented by formula (m-4) or its salt, and a third ink containing one or two or more of a compound represented by formula (c-1) or its salt, the compound represented by formula (c-2) or its salt, the compound represented by formula (c-3) or its salt, a compound represented by formula (c-4) or its salt, and the compound represented by formula (c-5) or its salt. ##STR00001##

An inkjet ink set consisting of a black inkjet ink, a cyan inkjet ink and two inkjet inks A and B, optionally complemented by a white ink and/or a colourless ink, wherein the inkjet ink A has a hue angle H* between 70 and 85 and a chroma C* between 30 and 80; the inkjet ink B has a hue angle H* between 20 and 40 and a chroma C* between 30 and 80; and the CIE L* a* b* coordinates were determined on polyethylene coated white paper for a 2° observer under a D50 light source.

An inkjet ink set consisting of a black inkjet ink, a cyan inkjet ink and two inkjet inks A and B, optionally complemented by a white ink and/or a colourless ink, wherein the inkjet ink A has a hue angle H* between 70 and 85 and a chroma C* between 30 and 80; the inkjet ink B has a hue angle H* between 20 and 40 and a chroma C* between 30 and 80; and the CIE L* a* b* coordinates were determined on polyethylene coated white paper for a 2° observer under a D50 light source.

A pretreatment liquid for an impermeable base material includes an anionic resin, and an aqueous medium, in which the anionic resin has a Clog P value of 1.40 or greater, and a content of a structural unit derived from an alkyl (meth)acrylate containing a chain alkyl group having 2 or more carbon atoms in the anionic resin is less than 5% by mass with respect to a total mass of the anionic resin.