Abstract: Provided is an ink composition for photo-curable inkjet printing, comprising a pigment, a photopolymerizable compound, and a photopolymerization initiator, wherein the photopolymerizable compound comprises 5 to 30% by mass of an amine-modified oligomer and 5 to 30% by mass of N,N-dimethylacrylamide, wherein the photopolymerization initiator comprises at least any one of ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and wherein a total amount of ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide is 12% by mass or less.

Abstract: A photocurable inkjet printing ink composition satisfies requirements A to F: A: the total content of compounds selected from vinyl methyl oxazolidinone, N,N-dimethylacrylamide, benzyl acrylate, and N-vinylcaprolactam, is 30.0% by mass or higher; B: the total content of compounds selected from saturated hydrocarbon group-containing monofunctional monomers with 6 or more carbon atoms and saturated hydrocarbon group-containing polyfunctional monomers with 6 or more carbon atoms is 15.0% by mass or higher in the photocurable inkjet printing ink composition; C: the content of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide is 3.5% by mass or higher; D: the total content of ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide is 6.0 to 12.0% by mass, and their ratio is 0.3 to 1.5; E: the content of amine-modified oligomer is 0.5 to 15.0% by mass in the photocurable inkjet printing ink composition; and F: a colorant is included.

Abstract: A photocurable inkjet printing ink composition satisfies all of requirements A to F: A: the total content of one or more compounds selected from vinyl methyl oxazolidinone, N,N-dimethylacrylamide, benzyl acrylate, and N-vinylcaprolactam is 30.0% by mass or higher; B: the total content of one or more compounds selected from saturated hydrocarbon group-containing monofunctional monomers with 6 or more carbon atoms and saturated hydrocarbon group-containing polyfunctional monomers with 6 or more carbon atoms is 15.0% by mass or higher; C: the content of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide is 2.5% by mass or lower; D: the content of ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide is 6.5 to 13.0% by mass; E: the content of amine-modified oligomer is 0.5 to 15.0% by mass; and F: as a colorant, a white pigment is contained by no more than 17.0% by mass, or not contained at all.

Abstract: Clear inks are prone to heat-induced micro-gelling that can cause their storage stability to drop, and micro-gelling may also occur in clear inks with the passage of time, in which case their inkjet discharge property may drop. As a solution, a photocurable clear ink composition for inkjet printing is provided, which contains a photopolymerizable compound, a photopolymerization initiator, and an inorganic filler of 1 to 200 nm in average grain size accounting for 0.05 to 5.0 percent by mass in the composition, and whose visible light transmission factor is 30% or higher.

Abstract: An object is to obtain a photocurable inkjet printing ink composition that demonstrates excellent preservation stability and discharge property, while also presenting curability under ultraviolet light from a light-emitting diode (LED) light source, as well as good adhesion, flexibility and tackiness. As a solution, a photocurable inkjet printing ink composition containing photopolymerizable compounds and photopolymerization initiator is provided, wherein the photocurable inkjet printing ink composition satisfies A to D: A. 2-(allyloxy methyl) methyl acrylate is contained by 5 to 40 percent by mass in all photopolymerizable compounds; B. multifunctional monomers and/or multifunctional oligomers of 0° C. or lower in glass transition temperature are contained by 5 to 20 percent by mass in all photopolymerizable compounds; C. amino group and/or amide group-containing monomers and/or oligomers are contained; and D. the ink composition has a viscosity of 30 mPa·s or lower at 25° C.

Abstract: Clear inks are prone to heat-induced micro-gelling that can cause their storage stability to drop, and micro-gelling may also occur in clear inks with the passage of time, in which case their inkjet discharge property may drop. As a solution, a photocurable clear ink composition for inkjet printing is provided, which contains a photopolymerizable compound, a photopolymerization initiator, and an inorganic filler of 1 to 200 nm in average grain size accounting for 0.05 to 5.0 percent by mass in the composition, and whose visible light transmission factor is 30% or higher.