Abstract: An ink jet method includes: a discharging step of discharging a radiation-curable ink jet composition onto a recording medium at an ink weight per dot of 22 ng/dot or less by using an ink jet head having a nozzle density of 600 npi or more and configured to discharge the radiation-curable ink jet composition; and an irradiating step of irradiating, with radiation, the radiation-curable ink jet composition attached to the recording medium. The radiation-curable ink jet composition contains polymerizable compounds containing a monofunctional monomer and a multifunctional monomer. The monofunctional monomer includes a nitrogen-containing monofunctional monomer. The amount of the monofunctional monomer is 90 mass % or more relative to the total amount of the polymerizable compound. The amount of the nitrogen-containing monofunctional monomer is from 1 to 15 mass % relative to the total amount of the polymerizable compounds.

Abstract: The present invention provides a photocurable ink composition for ink jet recording with excellent curability. The photocurable ink composition for ink jet recording includes polymerizable compounds, a photopolymerization initiator, and a colorant, wherein the polymerizable compounds include a vinyl ether group-containing (meth)acrylate represented by general formula (I): CH2?CR1—COOR2—O—CH?CH—R3??(I) (wherein R1 is a hydrogen atom or a methyl group, R2 is a divalent organic residue having 2 to 20 carbon atoms, and R3 is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms) and phenoxyethyl (meth)acrylate.

Abstract: A radiation-curable ink jet ink set according to the present disclosure includes: a radiation-curable clear ink composition; and a radiation-curable color ink composition, where: the clear ink composition contains a hydrogen abstraction-type photoinitiator and a hydroxy group-containing monomer; and the color ink composition contains an intramolecular cleavage-type photoinitiator and a colorant.

Abstract: A radiation-curable ink jet ink set includes a radiation-curable dark-colored ink having a surface tension ?1 and a radiation-curable light-colored ink having a surface tension ?2. The surface tensions of the radiation-curable inks satisfy ?1>?2.

Abstract: An ink jet printing apparatus includes a radiation-curable ink having a surface tension of 25.0 mN/m or less, and a printing head including a nozzle face having an opening of a nozzle through which the radiation-curable ink is ejected, and a liquid-repellent film on the nozzle face. The liquid-repellent film enables the radiation-curable ink to forms a contact angle of 60.0 degrees or more therewith.

Abstract: Provided is an ink jet recording method including: discharging first ultraviolet curable ink of a radical polymerization reaction type which contains a radical photopolymerization initiator and a radical polymerization compound and in which transmittance at a wavelength of 395 nm is equal to or less than 1%, onto a recording medium; and curing the first ultraviolet curable ink which is landed on the recording medium by irradiating the ink with ultraviolet light, in which a light source which initially emits the ultraviolet light in the curing of the ink is an ultraviolet light emitting diode in which peak intensity of the irradiated ultraviolet light is equal to or more than 800 mW/cm2.

Abstract: The present invention provides a photocurable ink composition for ink jet recording with excellent curability. The photocurable ink composition for ink jet recording includes polymerizable compounds, a photopolymerization initiator, and a colorant, wherein the polymerizable compounds include a vinyl ether group-containing (meth)acrylate represented by general formula (I): CH2?CR1—COOR2—O—CH?CH—R3??(I) (wherein R1 is a hydrogen atom or a methyl group, R2 is a divalent organic residue having 2 to 20 carbon atoms, and R3 is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms) and phenoxyethyl (meth)acrylate.

Abstract: A radiation-curable ink jet composition includes monomers, the monomers including 86% by mass or more of one or more monofunctional monomers relative to all the monomers, where a glass transition temperature of the radiation-curable ink jet composition calculated from glass transition temperatures of all the monomers is 42° C. or higher.

Abstract: An ink jet composition set includes a radiation-curable color composition, which contains a perinone-based pigment, a polymerizable compound and a polymerization initiator, and a radiation-curable clear composition, which contains an ultraviolet absorber, a polymerizable compound, and a polymerization initiator.

Abstract: Provided is an ink jet method including a step of ejecting a first composition from an ink jet head, the first composition being a radiation-curable composition having a hue angle of ?50° to ?5°, a step of ejecting a second composition from an ink jet head, the second composition being a radiation-curable composition having a hue angle of 5° to 50°, and an exposure step of curing the ejected first composition and the ejected second composition by exposing the ejected first composition to radiation within 1 second after landing of the ejected first composition and exposing the ejected second composition to radiation within 1 second after landing of the ejected second composition.

Abstract: Provided is an ink jet recording method including: discharging first ultraviolet curable ink of a radical polymerization reaction type which contains a radical photopolymerization initiator and a radical polymerization compound and in which transmittance at a wavelength of 395 nm is equal to or less than 1%, onto a recording medium; and curing the first ultraviolet curable ink which is landed on the recording medium by irradiating the ink with ultraviolet light, in which a light source which initially emits the ultraviolet light in the curing of the ink is an ultraviolet light emitting diode in which peak intensity of the irradiated ultraviolet light is equal to or more than 800 mW/cm2.

Abstract: A pigment dispersion containing a metal pigment, wherein the metal pigment contains plate-like particles, and in the case where the longitudinal diameter on the planar surface of the plate-like particle is X, the lateral diameter is Y, and the thickness is Z, the 50% average particle diameter R50 of a corresponding circle determined from the surface area in the X-Y plane of the plate-like particle is between 0.5 and 3 ?m, and the condition R50/Z>5 is satisfied.

Abstract: A pigment dispersion containing a metal pigment, wherein the metal pigment contains plate-like particles, and in the case where the longitudinal diameter on the planar surface of the plate-like particle is X, the lateral diameter is Y, and the thickness is Z, the 50% average particle diameter R50 of a corresponding circle determined from the surface area in the X-Y plane of the plate-like particle is between 0.5 and 3 ?m, and the condition R50/Z>5 is satisfied.

Abstract: A radiation-curable ink jet composition contains at least one monomer A represented by general formula (I): CH2?CR1—COOR2—O—CH?CH—R3, wherein R1 represents a hydrogen atom or a methyl group, R2 represents a divalent organic moiety having a carbon number of 2 to 20, and R3 represents a hydrogen atom or a monovalent organic moiety having a carbon number of 1 to 11. The composition also contains a cyclic, linear, or branched monomer B containing a (meth)acryloyloxy or (meth)acryloyl group in which the total number of nitrogen atoms and oxygen atoms other than the oxygen atoms contained in the (meth)acryloyloxy or (meth)acryloyl group is at least 2, and at least one monomer C represented by the following general formula (II): wherein n represents an integer of 2 to 6. The total content of monomer A is 10% by mass or more relative to the total mass of the ink jet composition.

Abstract: There is provided a maintenance liquid, which is used in maintenance of a device equipped with a discharge head for discharging an ultraviolet ray curable-type composition containing the acyl phosphine oxide-based photopolymerization initiator toward an attachment object, including a polymerizable compound in which a saturation solubility of an acyl phosphine oxide-based photopolymerization initiator at 20° C. is equal to or greater than 5.0% by mass.

Abstract: A radiation curable ink jet composition contains an acrylate oligomer (A), a monofunctional monomer (B), and a predetermined monomer (C), in which the acrylate oligomer (A) has 1 to 3 acryloyl groups, the glass transition temperature of a homopolymer of the monofunctional monomer (B) is ?20° C. or more and 30° C. or less, and the content of the monofunctional monomer (B) is 40% by mass or more based on the entire radiation curable ink jet composition.

Abstract: A radiation-curable ink jet composition contains monomer A represented by formula (1), a mono-, bi-, or trifunctional urethane (meth)acrylate oligomer, and an N-vinyl compound: CH2?CR1—COOR2—O—CH?CH—R3??(1) where R1 denotes —H or —CH3, R2 denotes an organic residue having 2 to 20 carbon atoms, and R3 denotes a hydrogen atom or an organic residue having 1 to 11 carbon atoms.

Abstract: A photocurable ink composition includes polymerizable compounds and a photopolymerization initiator. The polymerizable compounds include vinyl ether group-containing (meth)acrylic esters represented by the following Formula (I): CH2?CR1—COOR2—O—CH?CH—R3??(I) (wherein, R1 represents a hydrogen atom or a methyl group; R2 represents a divalent organic residue having 2 to 20 carbon atoms; and R3 represents a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms), dipropylene glycol di(meth)acrylate, and monofunctional (meth)acrylate having an aromatic ring skeleton. The ink composition includes a coloring material.

Abstract: A photo-curable ink jet ink set includes an undercoating photo-curable ink jet ink containing a (meth)acrylic acid ester having a vinyl ether group expressed by general formula (I), and an overcoating photo-curable ink jet ink. The undercoating photo-curable ink jet ink has a higher surface tension than the overcoating photo-curable ink jet ink.

Abstract: There is provided a radiation curable ink jet composition including: a monomer A that has one of a (meth)acryloyloxy group and a (meth)acryloyl group and has a cyclic structure containing one or more nitrogen atoms and one or more oxygen atoms in addition to the (meth)acryloyloxy group and the (meth)acryloyl group; and a monofunctional monomer B other than the monomer A; in which the content of the monomer A is equal to or less than 25% by mass with respect to the total mass of the composition, and in which mol average Tg of the monomer A and the monofunctional monomer B is equal to or greater than 45° C.