Abstract: By use of an ultraviolet curable inkjet ink comprising a colorant, a polymerizable monomer having a specific structure, ethoxyphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and at least one type selected from the group consisting of an acylphosphine oxide photopolymerization initiator different than the ethoxyphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, a benzophenone photopolymerization initiator, and an indane photopolymerization initiator, wherein the ratio of the content of the polymerizable monomer having the specific structure and the content of the ethoxyphenyl(2,4,6-trimethylbenzoyl)phosphine oxide is 2:1 to 8.5:1 by mass ratio, the content of a monofunctional monomer in the ultraviolet curable inkjet ink is 25% by mass or less, a printed matter having curability and coating film flexibility can be obtained regardless of the amount applied to a recording medium, and the discharge stability is also excellent.

Abstract: An ink set for single-pass printing including at least a cyan ink, a magenta ink, a yellow ink, and a gray ink, wherein the magenta ink satisfies a specific condition regarding spectral reflectance, and the gray ink has a spectral reflectance at a wavelength of 500 nm of 20 to 70% and satisfies the specific condition regarding spectral reflectance.

Abstract: By the use of an ultraviolet curable inkjet ink set for a line head printer comprising a lower layer ink containing a polymerizable monomer having a specific structure, and, a specific photopolymerization initiator, and an upper layer ink containing a polymerizable monomer having a specific structure and a specific photopolymerization initiator, wherein among the lower layer ink and the upper layer ink, one of the inks is a white ink and the other ink is a black ink, a good printed matter having excellent adhesion between a recording medium and the ink layer, and, between different ink layers can be obtained without generating curing wrinkles and curling over time even during high speed printing.

Abstract: An active energy ray curable inkjet ink comprising a pigment (A), a colorant derivative (B), a pigment dispersing resin (C) and a polymerizable compound (D), wherein the pigment (A) contains a C.I. pigment blue 15:6 and a quinacridone-based pigment at a specific amount and a specific ratio, the colorant derivative (B) contains a quinacridone-based pigment derivative, and the pigment dispersing resin (C) has an acid value and an amine value in a specific range.

Abstract: By use of an ultraviolet curable inkjet ink comprising a colorant, a polymerizable monomer having a specific structure, ethoxyphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and at least one type selected from the group consisting of an acylphosphine oxide photopolymerization initiator different than the ethoxyphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, a benzophenone photopolymerization initiator, and an indane photopolymerization initiator, wherein the ratio of the content of the polymerizable monomer having the specific structure and the content of the ethoxyphenyl(2,4,6-trimethylbenzoyl)phosphine oxide is 2:1 to 8.5:1 by mass ratio, the content of a monofunctional monomer in the ultraviolet curable inkjet ink is 25% by mass or less, a printed matter having curability and coating film flexibility can be obtained regardless of the amount applied to a recording medium, and the discharge stability is also excellent.

Abstract: By the use of an ultraviolet curable inkjet ink set for a line head printer comprising a lower layer ink containing a polymerizable monomer having a specific structure, and, a specific photopolymerization initiator, and an upper layer ink containing a polymerizable monomer having a specific structure and a specific photopolymerization initiator, wherein among the lower layer ink and the upper layer ink, one of the inks is a white ink and the other ink is a black ink, a good printed matter having excellent adhesion between a recording medium and the ink layer, and, between different ink layers can be obtained without generating curing wrinkles and curling over time even during high speed printing.

Abstract: An ink set for single-pass printing including at least a cyan ink, a magenta ink, a yellow ink, and a gray ink, wherein the magenta ink satisfies a specific condition regarding spectral reflectance, and the gray ink has a spectral reflectance at a wavelength of 500 nm of 20 to 70% and satisfies the specific condition regarding spectral reflectance.