An ink composition includes water, a resin, a coloring material, an alcohol (A) and a solvent (B). The alcohol (A) has a vapor pressure at 25° C. of 0.050 mmHg or greater and a solubility at 25° C. in 100 g of water of less than 3 g. The solvent (B) includes at least one selected from the group consisting of glycol ethers having a vapor pressure at 25° C. of less than 0.050 mmHg and a solubility at 25° C. in 100 g of water of 3 g or greater and alkanediols having a vapor pressure at 25° C. of less than 0.050 mmHg and a solubility at 25° C. in 100 g of water of 3 g or greater.

An ink includes a dielectric, non-aqueous carrier fluid. The ink also includes pigment particles within the carrier fluid and liquid resin in a dispersed phase encapsulating each of the pigment particles within the carrier fluid. The liquid resin is to be polymerized after the ink is applied to a substrate.

An ink includes a dielectric, non-aqueous carrier fluid. The ink also includes pigment particles within the carrier fluid and liquid resin in a dispersed phase encapsulating each of the pigment particles within the carrier fluid. The liquid resin is to be polymerized after the ink is applied to a substrate.

A printing method for printing a printing medium includes a non-white ink application step of applying an aqueous non-white ink composition containing a non-white coloring material onto the printing medium, and a white ink application step of applying an aqueous white ink composition containing a white coloring material onto the non-white ink composition on the printing medium to form a superimposed region. The non-white ink composition and the white ink composition each have an organic solvent content limited to 15% or less relative to the total mass of the corresponding ink composition. The mass ratio of the white ink composition to the non-white ink composition in the superimposed region is 1.5 or more in a portion to which the non-white ink composition is applied in an amount largest in the superimposed region.

A printing method for printing a printing medium includes a non-white ink application step of applying an aqueous non-white ink composition containing a non-white coloring material onto the printing medium, and a white ink application step of applying an aqueous white ink composition containing a white coloring material onto the non-white ink composition on the printing medium to form a superimposed region. The non-white ink composition and the white ink composition each have an organic solvent content limited to 15% or less relative to the total mass of the corresponding ink composition. The mass ratio of the white ink composition to the non-white ink composition in the superimposed region is 1.5 or more in a portion to which the non-white ink composition is applied in an amount largest in the superimposed region.

A printed object includes a substrate and a first information code disposed on the substrate, wherein: the first information code is constituted of an infrared ray-absorptive ink layer that has been printed with an infrared ray absorptive ink; and the infrared ray absorptive ink layer is configured such that, when a laminated body constituted of a test substrate made of the same material as that of the substrate, and a test infrared absorptive ink layer made of the same material as that of the infrared ray absorptive ink layer and disposed on the test substrate is subjected to a relative spectral reflectivity measurement on the test infrared ray absorptive ink layer side, with the test substrate as the reference (100% reflectivity), the minimum relative reflectivity in the visible region is 50% or higher, and the minimum relative reflectivity in the infrared region is 75% or lower.

A printed object includes a substrate and a first information code disposed on the substrate, wherein: the first information code is constituted of an infrared ray-absorptive ink layer that has been printed with an infrared ray absorptive ink; and the infrared ray absorptive ink layer is configured such that, when a laminated body constituted of a test substrate made of the same material as that of the substrate, and a test infrared absorptive ink layer made of the same material as that of the infrared ray absorptive ink layer and disposed on the test substrate is subjected to a relative spectral reflectivity measurement on the test infrared ray absorptive ink layer side, with the test substrate as the reference (100% reflectivity), the minimum relative reflectivity in the visible region is 50% or higher, and the minimum relative reflectivity in the infrared region is 75% or lower.

An aqueous ink for inkjet printing containing a colorant, a resin, a wetting agent, a surfactant, and water, in which the wetting agent contains a polyhydric alcohol at 60% by mass or more relative to the total amount of the wetting agent, the polyhydric alcohol having a solubility parameter value of 11.0 to 15.0, the resin contains a (meth)acrylic resin having a polydimethylsiloxane chain structure and a polyether chain structure on a side chain and a weight average molecular weight of 2,000 to 30,000, the (meth)acrylic resin is water soluble, the ratio of the blend amount of the polyhydric alcohol to the blend amount of the (meth)acrylic resin is 1500:1 to 6:1 by mass ratio, and the content of fluorine atoms in the total amount of the aqueous ink is 500 mass ppm or less.

An aqueous ink for inkjet printing containing a colorant, a resin, a wetting agent, a surfactant, and water, in which the wetting agent contains a polyhydric alcohol at 60% by mass or more relative to the total amount of the wetting agent, the polyhydric alcohol having a solubility parameter value of 11.0 to 15.0, the resin contains a (meth)acrylic resin having a polydimethylsiloxane chain structure and a polyether chain structure on a side chain and a weight average molecular weight of 2,000 to 30,000, the (meth)acrylic resin is water soluble, the ratio of the blend amount of the polyhydric alcohol to the blend amount of the (meth)acrylic resin is 1500:1 to 6:1 by mass ratio, and the content of fluorine atoms in the total amount of the aqueous ink is 500 mass ppm or less.

A liquid discharge apparatus includes an apparatus body, a liquid discharge device configured to discharge a liquid, a carriage in the apparatus body, the carriage configured to movably mount the liquid discharge device, a first storage container detachably attached to the carriage, the first storage container configured to store a first liquid, and a second storage container detachably attached to the apparatus body, the second storage container configured to store a second liquid different from the first liquid.