Abstract: An ink composition at least contains a compound A having a hydroxy group and a compound B having an aldehyde group as polyoxyalkylene alkyl ether surfactants. The mass ratio of the compound B to the compound A is 0.5×10?4 to 30×10?4.

Abstract: An ink composition contains resin particles, a pigment, glycol ether, and water, wherein the resin particles satisfy the condition defined by Relational Expression (1) 1.0?(?2/?1)?12.5??(1) (where ?1 represents the volume average particle size of the resin particles in a solution containing 20 mass % of the resin particles and 80 mass % of water, and ?2 represents the volume average particle size of the resin particles in a solution containing 90 mass % of the resin particles and 10 mass % of water).

Abstract: There is provided an ink set including at least: a yellow ink; a magenta ink; and a cyan ink, in which the yellow ink includes one or more kinds selected from a group consisting of coloring materials represented by the following Formulae (Y-1) and (Y-2), the magenta ink includes one or more kinds selected from a group consisting of coloring materials represented by the following Formulae (M-1) and (M-2), and the cyan ink includes one or more kinds selected from a group consisting of coloring materials represented by the following Formulae (C-1) and (C-2).

Abstract: An aqueous ink set for ink jet recording includes an aqueous pigment ink containing water and a pigment as a coloring agent and an aqueous dye ink containing water and a dye as a coloring agent, in which the concentration of the divalent metal ions of the pigment ink is 10 ppm or more, and the potassium ion concentration of the dye ink is 50 ppm or less.

Abstract: There is provided an ink composition, including: a dye (M-2); a dye (Y-1); an alkylene oxide adduct of acetylene glycol having a main chain of 12 or more carbon atoms; acetylene glycol having a main chain of 10 or more carbon atoms; and a polyoxyalkylene alkyl ether, in which the content ratio A of the dye (M-2) and the dye (Y-1) (the dye (M-2):the dye (Y-1)) is 1.25:1 to 4.75:1.

Abstract: There is provided an ink composition, including: a combination of specific dyes, in which the dynamic contact angle of the ink to a silicon wafer is 24° or lower at 100 msec after dropping, and is 9° or lower at 5,100 msec after dropping.

Abstract: An aqueous ink set for ink jet recording includes an aqueous pigment ink containing water and a pigment as a coloring agent and an aqueous dye ink containing water and a dye as a coloring agent, in which the concentration of the divalent metal ions of the pigment ink is 10 ppm or more, and the potassium ion concentration of the dye ink is 50 ppm or less.

Abstract: An ink composition at least contains a compound A having a hydroxy group and a compound B having an aldehyde group as polyoxyalkylene alkyl ether surfactants. The mass ratio of the compound B to the compound A is 0.5×10?4 to 30×10?4.

Abstract: There is provided an ink composition including: a predetermined dye (C-1); a dye (C-2) containing at least one of C.I. Direct Blues 86 and 199; an alkylene oxide adduct of an acetylene glycol having a main chain of 12 or more carbon atoms; an acetylene glycol having a main chain of 10 or more carbon atoms; and a polyoxyalkylene alkyl ether, in which the content ratio A of the dye (C-1) and the dye (C-2) (the dye (C-1):the dye (C-2)) is 7:3 to 9.5:0.5, and the content of the dye (C-1) is 2.0 mass % to 5.0 mass %.

Abstract: An ink-jet ink set includes a black ink containing carbon black; a cyan ink containing a first cyan dye; a magenta ink containing a first magenta dye; a yellow ink containing a first yellow dye; and a gray ink containing a second cyan dye, a second magenta dye, and a second yellow dye. The cyan ink, the magenta ink, the yellow ink, and the gray ink have a ROD of 65% or more, the ROD being defined by Equation (A). The gray ink has an OD value of 1.40 to less than 2.30, the OD value being defined by Equation (B).

Abstract: An ink composition includes, as dyes, a dye (Bk-1) represented by the formula (Bk-1); and a dye (Bw-1) represented by the formula (Bw-1), in which a content ratio A (dye (Bk-1):dye (Bw-1)) of the dye (Bk-1) and the dye (Bw-1) is 100:18 to 100:40.

Abstract: There is provided an ink composition, including: a dye (M-2); a dye (Y-1); an alkylene oxide adduct of acetylene glycol having a main chain of 12 or more carbon atoms; acetylene glycol having a main chain of 10 or more carbon atoms; and a polyoxyalkylene alkyl ether, in which the content ratio A of the dye (M-2) and the dye (Y-1) (the dye (M-2):the dye (Y-1)) is 1.25:1 to 4.75:1.

Abstract: An ink composition includes, as dyes, a dye (Bk-1) represented by the formula (Bk-1); and a dye (Bw-1) represented by the formula (Bw-1), in which a content ratio A (dye (Bk-1):dye (Bw-1)) of the dye (Bk-1) and the dye (Bw-1) is 100:18 to 100:40.

Abstract: There is provided an ink composition including: a predetermined dye (C-1); a dye (C-2) containing at least one of C.I. Direct Blues 86 and 199; an alkylene oxide adduct of an acetylene glycol having a main chain of 12 or more carbon atoms; an acetylene glycol having a main chain of 10 or more carbon atoms; and a polyoxyalkylene alkyl ether, in which the content ratio A of the dye (C-1) and the dye (C-2) (the dye (C-1):the dye (C-2)) is 7:3 to 9.5:0.5, and the content of the dye (C-1) is 2.0 mass % to 5.0 mass %.

Abstract: There is provided an ink composition, including: a combination of specific dyes, in which the dynamic contact angle of the ink to a silicon wafer is 24° or lower at 100 msec after dropping, and is 9° or lower at 5,100 msec after dropping.

Abstract: There is provided an ink set including at least: a yellow ink; a magenta ink; and a cyan ink, in which the yellow ink includes one or more kinds selected from a group consisting of coloring materials represented by the following Formulae (Y-1) and (Y-2), the magenta ink includes one or more kinds selected from a group consisting of coloring materials represented by the following Formulae (M-1) and (M-2), and the cyan ink includes one or more kinds selected from a group consisting of coloring materials represented by the following Formulae (C-1) and (C-2).

Abstract: An ink-jet ink set includes a black ink containing carbon black; a cyan ink containing a first cyan dye; a magenta ink containing a first magenta dye; a yellow ink containing a first yellow dye; and a gray ink containing a second cyan dye, a second magenta dye, and a second yellow dye. The cyan ink, the magenta ink, the yellow ink, and the gray ink have a ROD of 65% or more, the ROD being defined by Equation (A). The gray ink has an OD value of 1.40 to less than 2.30, the OD value being defined by Equation (B).