# US 2018/0022949 A1 · Inkjet ink and image-forming method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0022949 A1 - Document ID: US20180022949A1 - Status: Published application - Kind: A1 - Application number: 15/549,865 - Filed: 2016-02-02 - Published: 2018-01-25 - Earliest claimed: 2015-02-09 - Assignees: Konica Minolta, Inc. - Applicants: Konica Minolta, Inc. - Inventors: Masashi IKEDA - Web page: https://patentgrep.com/patent/US20180022949A1 ## CPC - C09D 11/38: characterised by non-macromolecular additives other than solvents, pigments or dyes - C09D 11/101: Inks specially adapted for printing processes involving curing by wave energy or particle radiation, e.g. with UV-curing following the printing - C09D 11/12: based on waxes or bitumen - C09D 11/30: Inkjet printing inks - C09D 11/322: Pigment inks - C09D 11/34: Hot-melt inks - C09D 11/54: Inks based on two liquids, one liquid being the ink, the other liquid being a reaction solution, a fixer or a treatment solution for the ink - B41M 5/0011: {Pre-treatment or treatment during printing of the recording material, e.g. heating, irradiating (after-treatment of prints B41M7/00; printers for treating or overcoating copy materials before, during or after printing B41J11/0015)} - B41M 7/0081: {using electromagnetic radiation or waves, e.g. ultraviolet radiation, electron beams} - C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D) - B41M: PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING, (correction of typographical errors B41J; processes for applying transfer pictures or the like B44C1/16; fluid media for correction of typographical errors by coating C09D10/00; printing textiles D06P) ## Abstract The purpose of the present invention is to provide an active ray-curable inkjet ink capable of further enhancing gloss uniformity, surface curability, and scratch resistance of a formed image. The purpose is achieved by an active ray-curable inkjet ink containing a polymerization initiator, a photopolymerizable compound, and a gelling agent, and that undergoes a reversible sol-gel phase transition by temperature change. The inkjet ink contains a polymerization initiator with a molecular weight of 360 or more, and a polyfunctional photopolymerizable compound. The inkjet ink contains 3.0 mass % or more and less than 8.0 mass % of the polymerization initiator with a molecular weight of 360 or more, 1.0 mass % or more and less than 5.0 mass % of the gelling agent, less than 0.1 mass % of the initiator with a molecular weight of 360 or more, and less than 5.0 mass % of the monofunctional photopolymerizable compound. ## Claims ### Claim 1 An actinic radiation-curable inkjet ink which reversibly undergoes sol-gel phase transition through a temperature change, the inkjet ink comprising: one or more polymerization initiators, one or more photocurable compounds, and a gelling agent, wherein: the polymerization initiators include one or more polymerization initiators with a molecular weight of 360 or more; the photocurable compounds include a polyfunctional photocurable compound; a content of the at least one polymerization initiator with a molecular weight of 360 or more is 3.0 mass % or more and less than 8.0 mass %; a content of the gelling agent is 1.0 mass % or more and less than 5.0 mass %; a content of a polymerization initiator with a molecular weight of less than 360 is less than 0.1 mass %; and a content of a monofunctional photocurable compound is less than 5.0 mass %. ### Claim 2 (depends on 1) The inkjet ink according to claim 1, wherein the polymerization initiators with a molecular weight of 360 or more include a radical polymerization initiator having a bisacylphosphine structure. ### Claim 3 (depends on 2) The inkjet ink according to claim 2, wherein the polymerization initiators with a molecular weight of 360 or more further include a polymerization initiator having a thioxanthone structure. ### Claim 4 (depends on 1) The inkjet ink according to claim 1, wherein the gelling agent is substantially free of a photocurable functional group. ### Claim 5 (depends on 1) The inkjet ink according to claim 1, wherein the gelling agent includes a compound represented by general formula G1: R1-CO-R2 General formula G1 wherein R1 and R2 are each independently a C9-C25 linear or branched hydrocarbon group, or a compound represented by general formula G2: R3-COO-R4 General formula G2 wherein R3 and R4 are each independently a C9-C25 linear or branched hydrocarbon group. ### Claim 6 (depends on 1) An image forming method comprising ejecting the inkjet ink according to claim 1 from a nozzle of an inkjet head to allow the inkjet ink to impact on a recording medium, and curing the inkjet ink by irradiating the impacted inkjet ink with actinic radiation. ### Claim 7 (depends on 6) The image forming method according to claim 6, further comprising, before or simultaneously with the allowing of the inkjet ink to impact, controlling a surface temperature at 20° C. or higher and 40° C. or lower of the recording medium on a side where the inkjet ink impacts.