Abstract: In one aspect of the present disclosure, there is provided an optical wavelength conversion member including a polycrystalline ceramic sintered body containing, as main components, Al2O3 crystal grains and crystal grains represented by formula X3Al5O12:Ce. In the optical wavelength conversion member 9, atoms of element X are present also in an Al2O3 crystal grain adjacent to the interface between the Al2O3 crystal grain and an X3Al5O12:Ce crystal grain.

Abstract: The purpose of the present invention is to provide an actinic radiation curable inkjet ink which has less color mixing, which can obtain white ink with fewer surface irregularities and excellent smoothness, which has excellent actinic radiation transmittance and curability, and which enables sol-gel phase transition by temperature change, and to provide an inkjet image forming method, and a recording medium on which an image has been formed using the inkjet ink. This purpose is achieved by an actinic radiation curable inkjet ink that contains a photopolymerizable compound, a photo initiator, a gelling agent, and a white pigment, wherein the white pigment contains titanium oxide, the gelling agent contains at least one type of gelling agent A that contains an alkyl chain comprising a straight chain portion with 12-26 carbon atoms, wherein the content of the gelling agent A is 5-35 mass % of the content of the titanium oxide.

Abstract: The present invention relates to an image forming method and an image forming apparatus by an inkjet method using a gel ink, which minimize a gloss difference between an image-formed region and an image-less region, regardless of a type of a paper substrate used. The image forming method of the present invention is a method for forming an image on a paper substrate by using an inkjet ink that undergoes a temperature-induced sol-gel phase transition. The image forming method includes: a step of subjecting a paper substrate to a corona discharge treatment; a step of ejecting liquid droplets of inkjet ink and landing the droplets on a surface of the paper substrate subjected to the corona discharge treatment; and a step of irradiating the droplets of the inkjet ink landed on the paper substrate with an actinic light ray to cure the inkjet ink.

Abstract: Purpose is to provide an inkjet recording method for forming high-quality color image on a thick recording medium having low thermal conductance rate. The present invention is a single-pass inkjet recording method using an ink set including at least two active ray-curing color inks, and a recording medium having thermal conductivity of less than 0.10 W/(m·K) and thickness of 0.4 mm or more. The ink set containing two color inks satisfy only condition (a), and the ink set containing three or more color inks satisfy conditions (a) and (b): (a) most downstream color ink has a gelation temperature which is 3.0° C. to 15.0° C. higher than that of most upstream color ink, and (b) second or subsequent color ink from the most upstream position in conveyance direction has a gelation temperature which is the same as or higher than that of an adjacent color ink at the upstream position.

Abstract: The present invention relates to an image forming method and an image forming apparatus by an inkjet method using a gel ink, which minimize a gloss difference between an image-formed region and an image-less region, regardless of a type of a paper substrate used. The image forming method of the present invention is a method for forming an image on a paper substrate by using an inkjet ink that undergoes a temperature-induced sol-gel phase transition. The image forming method includes: a step of subjecting a paper substrate to a corona discharge treatment; a step of ejecting liquid droplets of inkjet ink and landing the droplets on a surface of the paper substrate subjected to the corona discharge treatment; and a step of irradiating the droplets of the inkjet ink landed on the paper substrate with an actinic light ray to cure the inkjet ink.

Abstract: The present invention provides an image forming method capable of suppressing glossiness unevenness in one image with curability of an ink droplet having been caused to land on a recording medium increased. The image forming method includes: preparing an actinic radiation-curable inkjet ink containing a radical polymerizable compound, a photopolymerization initiator, a gelling agent, and a nucleating agent; discharging a droplet of the actinic radiation-curable inkjet ink to cause the droplet to land on a surface of a recording medium; and curing the droplet by irradiating the droplet having been caused to land on the recording medium with actinic radiation. The gelling agent contains, in a molecular structure thereof, a polar group, and a C15-26 alkyl group, the nucleating agent is a (poly)glycerin fatty acid ester, and an oxygen concentration in an atmosphere where irradiation with the actinic radiation is conducted is less than 20 vol %.

Abstract: The present invention provides an image forming method capable of suppressing glossiness unevenness in one image with curability of an ink droplet having been caused to land on a recording medium increased. The image forming method includes: preparing an actinic radiation-curable inkjet ink containing a radical polymerizable compound, a photopolymerization initiator, a gelling agent, and a nucleating agent; discharging a droplet of the actinic radiation-curable inkjet ink to cause the droplet to land on a surface of a recording medium; and curing the droplet by irradiating the droplet having been caused to land on the recording medium with actinic radiation. The gelling agent contains, in a molecular structure thereof, a polar group, and a C15-26 alkyl group, the nucleating agent is a (poly)glycerin fatty acid ester, and an oxygen concentration in an atmosphere where irradiation with the actinic radiation is conducted is less than 20 vol %.

Abstract: Purpose is to provide an inkjet recording method for forming high-quality color image on a thick recording medium having low thermal conductance rate. The present invention is a single-pass inkjet recording method using an ink set including at least two active ray-curing color inks, and a recording medium having thermal conductivity of less than 0.10 W/(m·K) and thickness of 0.4 mm or more. The ink set containing two color inks satisfy only condition (a), and the ink set containing three or more color inks satisfy conditions (a) and (b): (a) most downstream color ink has a gelation temperature which is 3.0° C. to 15.0° C. higher than that of most upstream color ink, and (b) second or subsequent color ink from the most upstream position in conveyance direction has a gelation temperature which is the same as or higher than that of an adjacent color ink at the upstream position.

Abstract: An inkjet recording method using an active light-curable inkjet ink according to the present invention is characterized in that: the inkjet ink contains at least a gelling agent, a photopolymerizable compound and a photopolymerization initiator; the gelling temperature T1 (° C.) of the active light-curable inkjet ink, the temperature T2 (° C.) of the ink at the time when the active light-curable inkjet ink landed on a recording medium, and the temperature T3 (° C.) of the ink at the time when the active light-curable inkjet ink is irradiated with active light satisfy the relationship T1 (° C.)>T2 (° C.)>T3 (° C.); and the solubility of the gelling agent in the photopolymerizable compound at T3 (° C.) is less than 0.1% by mass. This inkjet recording method is capable of suppressing blooming, while at least maintaining the leveling properties and the pinning properties of an inkjet ink.

Abstract: The purpose of the present invention is to provide an actinic radiation curable inkjet ink which has less color mixing, which can obtain white ink with fewer surface irregularities and excellent smoothness, which has excellent actinic radiation transmittance and curability, and which enables sol-gel phase transition by temperature change, and to provide an inkjet image forming method, and a recording medium on which an image has been formed using the inkjet ink. This purpose is achieved by an actinic radiation curable inkjet ink that contains a photopolymerizable compound, a photo initiator, a gelling agent, and a white pigment, wherein the white pigment contains titanium oxide, the gelling agent contains at least one type of gelling agent A that contains an alkyl chain comprising a straight chain portion with 12-26 carbon atoms, wherein the content of the gelling agent A is 5-35 mass % of the content of the titanium oxide.

Abstract: An inkjet recording method using an active light-curable inkjet ink according to the present invention is characterized in that: the inkjet ink contains at least a gelling agent, a photopolymerizable compound and a photopolymerization initiator; the gelling temperature T1 (° C.) of the active light-curable inkjet ink, the temperature T2 (° C.) of the ink at the time when the active light-curable inkjet ink landed on a recording medium, and the temperature T3 (° C.) of the ink at the time when the active light-curable inkjet ink is irradiated with active light satisfy the relationship T1 (° C.)>T2 (° C.)>T3 (° C.); and the solubility of the gelling agent in the photopolymerizable compound at T3 (° C.) is less than 0.1% by mass. This inkjet recording method is capable of suppressing blooming, while at least maintaining the leveling properties and the pinning properties of an inkjet ink.

Abstract: Provided is an ultraviolet curable inkjet ink and an inkjet image formation method that uses said inkjet ink. The inkjet ink can be ejected from an inkjet head without being diluted by a solvent, has high photo curing sensitivity and produces high quality images with excellent weather resistance (smear resistance). The inkjet ink is characterized by a polymerizable compound which contains a maleimide compound having a chiral group and a compound selected from a vinyl ether compound and a N-vinyl compound.

Abstract: In an ink jet ink containing a pigment, a binder resin, water, an organic solvent, and a surfactant, the surface tension of the ink is in a region defined by ?0??x?1.0 (?0: surface tension before evaporation, ?x: surface tension at an evaporation rate X %) when the evaporation rate X of the ink is in a range of 0<X(%)?20; the ink jet ink contains two or more organic solvents; and the content of an organic solvent of which the sum ?SP of the hydrogen bonding term and the polarity term of the solubility parameter is 8 to 18 MPa1/2 is 30 mass % or more and less than 95 mass % of the total amount of the organic solvents; and the content of the surfactant is less than the critical micelle concentration of the surfactant.

Abstract: Provided is an ultraviolet curable inkjet ink and an inkjet image formation method that uses said inkjet ink. The inkjet ink can be ejected from an inkjet head without being diluted by a solvent, has high photo curing sensitivity and produces high quality images with excellent weather resistance (smear resistance). The inkjet ink is characterized by a polymerizable compound which contains a maleimide compound having a chiral group and a compound selected from a vinyl ether compound and a N-vinyl compound.

Abstract: The present invention provides an actinic energy radiation curable ink-jet ink exhibiting excellent ink storage stability, nozzle ink repellency, and ejection stability, and also exhibiting excellent curability, anti-abrasion properties, solvent resistance, flexibility, weather resistance, and substrate adhesion properties even under various ambience factors and irradiation conditions, as well as an ink-jet recording method and printed matter using the same. In an actinic energy radiation curable ink-jet ink containing a cationically polymerizable compound and a photo-cationic polymerization initiator, an actinic energy radiation curable ink-jet ink wherein a cationically polymerizable compound having a vinyl ether group as a reactive group is contained at 50.0% by mass or more and the halogen ion content is 1.0 ?g/g of the ink-100 ?g/g of the ink.

Abstract: In an ink jet ink containing a pigment, a binder resin, water, an organic solvent, and a surfactant, the surface tension of the ink is in a region defined by ?0??x?1.0 (?0: surface tension before evaporation, ?x: surface tension at an evaporation rate X %) when the evaporation rate X of the ink is in a range of 0<X(%)?20; the ink jet ink contains two or more organic solvents; and the content of an organic solvent of which the sum ?SP of the hydrogen bonding term and the polarity term of the solubility parameter is 8 to 18 MPa1/2 is 30 mass % or more and less than 95 mass % of the total amount of the organic solvents; and the content of the surfactant is less than the critical micelle concentration of the surfactant.

Abstract: Provided is an actinic energy radiation curable ink-jet ink, an ink-jet recording method, and printed matter satisfying ink storage stability, ejection stability, weather resistance, flexibility, safety, odorless properties. An actinic energy radiation curable ink-jet ink comprises a cationically polymerizable compound and a photo-cationic polymerization initiator, wherein the cationically polymerizable compound comprises a vinyl ether group as a reactive group, the photo-cationic polymerization initiator is a photo acid generator, an amount of generation of protonic acid from the photo acid generator is 1×10?4 mol/L or less, and comprising a radical polymerization inhibitor; wherein the amount of generation of protonic acid is defined as a difference of a hydrogen ion concentration (mol/L) in dioxane solution between immediately after preparation and after refluxing when 0.02 mol/L of the photo acid generator in dioxane solution are refluxed 20 hours under atmospheric pressure.

Abstract: The present invention provides an actinic energy radiation curable ink-jet ink exhibiting excellent ink storage stability, nozzle ink repellency, and ejection stability, and also exhibiting excellent curability, anti-abrasion properties, solvent resistance, flexibility, weather resistance, and substrate adhesion properties even under various ambience factors and irradiation conditions, as well as an ink-jet recording method and printed matter using the same. In an actinic energy radiation curable ink-jet ink containing a cationically polymerizable compound and a photo-cationic polymerization initiator, an actinic energy radiation curable ink-jet ink wherein a cationically polymerizable compound having a vinyl ether group as a reactive group is contained at 50.0% by mass or more and the halogen ion content is 1.0 ?g/g of the ink-100 ?g/g of the ink.