# US 8,740,368 B2 · Ink composition, ink set and inkjet 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 8,740,368 B2 - Document ID: US8740368B2 - Status: Granted - Kind: B2 - Application number: 13/047,819 - Filed: 2011-03-15 - Published: 2011-09-22 - Granted: 2014-06-03 - Earliest claimed: 2010-03-18 - Assignees: FUJIFILM Corporation - Applicants: Masao Ikoshi; Jun Matsumoto - Inventors: Masao Ikoshi; Jun Matsumoto - Web page: https://patentgrep.com/patent/US8740368B2 ## CPC - C09D 11/40: Ink-sets specially adapted for multi-colour inkjet printing - C09D 11/322: Pigment inks - C09D 11/38: characterised by non-macromolecular additives other than solvents, pigments or dyes - 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 - 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) ## Abstract The present invention provides an ink composition for inkjet recording, containing colloidal silica, urea, a coloring material, and water. ## Claims ### Claim 1 An ink composition for inkjet recording, comprising colloidal silica, urea, a pigment, and water. ### Claim 2 (depends on 1) The ink composition according to claim 1, wherein a content ratio of the urea to the colloidal silica (urea/colloidal silica) is from 5 to 1000. ### Claim 3 (depends on 1) The ink composition according to claim 1, wherein a volume average particle diameter of the colloidal silica is 20 nm or less. ### Claim 4 (depends on 1) The ink composition according to claim 1, wherein the pigment is coated with a water-insoluble resin by a phase inversion emulsification method. ### Claim 5 (depends on 1) The ink composition according to claim 1, wherein the content of the colloidal silica is from 0.01% by mass to 3.0% by mass with respect to the total mass of the ink composition. ### Claim 6 (depends on 1) The ink composition according to claim 1, having a pH of from 7.5 to 10.0 at 25° C. ### Claim 7 (depends on 1) The ink composition according to claim 1, wherein the content of the urea is 1% by mass or higher but lower than 15% by mass with respect to the total mass of the ink composition. ### Claim 8 (depends on 1) The ink composition according to claim 1, further comprising resin particles. ### Claim 9 (depends on 8) The ink composition according to claim 8, wherein the resin particles are self-dispersing polymer particles. ### Claim 10 (depends on 1) An ink set comprising the ink composition for inkjet recording according to claim 1 and a treatment liquid that forms an aggregate when contacted with the ink composition. ### Claim 11 (depends on 1) An inkjet image forming method comprising ejecting the ink composition for inkjet recording according to claim 1 from an inkjet head equipped with a silicone nozzle plate onto a recording medium to form an image. ### Claim 12 (depends on 11) The inkjet image forming method according to claim 11 further comprising applying a treatment liquid that forms an aggregate when contacted with the ink composition. ### Claim 13 (depends on 11) The inkjet image forming method according to claim 11, wherein the recording medium is a printing paper which contains cellulose as a main component.