An inkjet printing apparatus includes a discharge head that discharges ink, and a housing that contains the discharge head, wherein the housing contains a first ink storage member and a second ink storage member that each store ink, and the ink is supplied from each of the first ink storage member and the second ink storage member to the discharge head, wherein the first ink storage member is an ink cartridge not having an ink refilling port for enabling ink refilling by opening a stopper member, and detachable from the inkjet printing apparatus, and wherein the second ink storage member has the ink refilling port.

An inkjet printing apparatus includes a discharge head that discharges ink, and a housing that contains the discharge head, wherein the housing contains a first ink storage member and a second ink storage member that each store ink, and the ink is supplied from each of the first ink storage member and the second ink storage member to the discharge head, wherein the first ink storage member is an ink cartridge not having an ink refilling port for enabling ink refilling by opening a stopper member, and detachable from the inkjet printing apparatus, and wherein the second ink storage member has the ink refilling port.

An object is to provide a printing ink that has high environmental friendliness and is excellent in quick dry-curability of a coating when a plasma is used as a curing system. A solution is to provide an ink composition for plasma curing including a photocatalyst compound and/or a composite of a metal component and a photocatalyst compound and to provide an additive for an ink composition for plasma curing, the additive including a photocatalyst compound and/or a composite of a metal component and a photocatalyst compound.

An object is to provide a printing ink that has high environmental friendliness and is excellent in quick dry-curability of a coating when a plasma is used as a curing system. A solution is to provide an ink composition for plasma curing including a photocatalyst compound and/or a composite of a metal component and a photocatalyst compound and to provide an additive for an ink composition for plasma curing, the additive including a photocatalyst compound and/or a composite of a metal component and a photocatalyst compound.

An aqueous ink jet ink composition according to the present embodiment is an aqueous ink jet ink composition for use in an ink jet recording method that includes ejecting ink from an ink jet head. The ink jet head includes nozzles that have a side wall surface, and the side wall surface has a scalloped shape in which a scallop width S1 and a notch depth S2 satisfy S1/S2≥4. The aqueous ink jet ink composition includes a self-dispersed pigment and a solvent that includes a compound represented by formula (1) below.
R.sub.1—O—R.sub.2—OH  (1) In formula (1), R.sub.1 represents a hydrogen atom, a methyl group, or an ethyl group, and R.sub.2 represents a divalent saturated hydrocarbon group having 5 or fewer carbon atoms or represents a group represented by formula (2) below.
R.sub.3—O—R.sub.4  (2) In formula (2), R.sub.3 and R.sub.4 each independently represent a divalent saturated hydrocarbon group having 2 or 3 carbon atoms.

An aqueous ink jet ink composition according to the present embodiment is an aqueous ink jet ink composition for use in an ink jet recording method that includes ejecting ink from an ink jet head. The ink jet head includes nozzles that have a side wall surface, and the side wall surface has a scalloped shape in which a scallop width S1 and a notch depth S2 satisfy S1/S2≥4. The aqueous ink jet ink composition includes a self-dispersed pigment and a solvent that includes a compound represented by formula (1) below.
R.sub.1—O—R.sub.2—OH  (1) In formula (1), R.sub.1 represents a hydrogen atom, a methyl group, or an ethyl group, and R.sub.2 represents a divalent saturated hydrocarbon group having 5 or fewer carbon atoms or represents a group represented by formula (2) below.
R.sub.3—O—R.sub.4  (2) In formula (2), R.sub.3 and R.sub.4 each independently represent a divalent saturated hydrocarbon group having 2 or 3 carbon atoms.

An aqueous ink composition includes a film-forming retardation additive, which enhances the pigment efficiency in the ink composition. A method for making such an ink and a method of printing with such an ink are also disclosed.

An aqueous ink composition includes a film-forming retardation additive, which enhances the pigment efficiency in the ink composition. A method for making such an ink and a method of printing with such an ink are also disclosed.

An ink jet process includes an ejection step, in which a radiation-curable ink jet composition is ejected from an ink jet head to a recording medium, and a curing step, in which the ejected ink jet composition is irradiated with radiation to give a cured coating of the ink jet composition. The ink jet composition contains at least one polymerizable compound, at least one photopolymerization initiator, and C.I. Pigment Red 57:1. The C.I. Pigment Red 57:1 constitutes 4.0% by mass or more of the total amount of the ink jet composition, and the cured coating has a maximum thickness of 5 μm or less.

An ink jet process includes an ejection step, in which a radiation-curable ink jet composition is ejected from an ink jet head to a recording medium, and a curing step, in which the ejected ink jet composition is irradiated with radiation to give a cured coating of the ink jet composition. The ink jet composition contains at least one polymerizable compound, at least one photopolymerization initiator, and C.I. Pigment Red 57:1. The C.I. Pigment Red 57:1 constitutes 4.0% by mass or more of the total amount of the ink jet composition, and the cured coating has a maximum thickness of 5 μm or less.