# US 7,608,203 B2 · Metallic colloidal solution and inkjet-use metallic ink > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,608,203 B2 - Document ID: US7608203B2 - Status: Granted - Kind: B2 - Application number: 12/195,777 - Filed: 2008-08-21 - Published: 2008-12-18 - Granted: 2009-10-27 - Earliest claimed: 2004-03-01 - Assignees: Sumitomo Electric Industries, Ltd. - Inventors: Issei Okada; Kohei Shimoda - Web page: https://patentgrep.com/patent/US7608203B2 ## CPC - C09D 11/322: Pigment inks - C09D 11/52: Electrically conductive inks - H01B 1/22: the conductive material comprising metals or alloys - H05K 1/097: {Inks comprising nanoparticles and specially adapted for being sintered at low temperature (H05K1/095 takes precedence)} - H05K 3/1241: {by ink-jet printing or drawing by dispensing} - 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) - H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K}) - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract A metallic colloidal solution (a) includes a water-based dispersion medium that is easy in handling with regard to safety and environment and metallic particles having a uniform particle diameter and being excellent in properties such as conductivity and (b) has properties suitable for various printing methods and ink-applying methods. In addition, an inkjet-use metallic ink incorporating the metallic colloidal solution has properties suitable for the inkjet printing method. The metallic particles are deposited by reducing metallic ions in water and have a primary-particle diameter of at most 200 nm. The dispersion medium is made of a mixed solvent of water and a water-soluble organic solvent. The metallic particles are dispersed in the dispersion medium under the presence of a dispersant having a molecular weight of 200 to 30,000. ## Claims ### Claim 1 A metallic colloidal solution comprising: (a) metallic particles that (a1) are deposited by reducing metallic ions in water, (a2) have a primary-particle diameter of at most 200 nm, and (a3) made of a metal selected from the group consisting of nickel, copper, silver, gold, platinum, palladium, and an alloy of these metals; (b) a dispersant having a molecular weight of 200 to 30,000; and (c) a dispersion medium made of a mixed solvent of water and a water-soluble organic solvent, wherein the water-soluble organic solvent is one of a mixture of glycol ether and alcohol and a mixture of glycol ether and keton, and the ratio of the water-soluble organic solvent to the mixed solvent is at least 70 percent, but less than 100 percent by weight. ### Claim 2 (depends on 1) A metallic colloidal solution as defined by claim 1, the metallic colloidal solution being produced: (a) by using as a starting material a water-based metallic colloidal solution obtained by depositing metallic particles through the reduction of metallic ions in water; and (b) without undergoing a process that completely separates the metallic particles from water. ### Claim 3 (depends on 1) A metallic colloidal solution as defined by claim 1, wherein the content of the metallic particles is 0.1 to 90 wt. %. ### Claim 4 (depends on 1) A metallic colloidal solution as defined by claim 1, wherein the dispersant is an organic compound that does not contain any of sulfur, phosphorus, boron, and a halogen atom. ### Claim 5 (depends on 1) A metallic colloidal solution as defined by claim 1, wherein the amount of the dispersant is 2 to 30 weight parts per 100 weight parts of the metallic particles. ### Claim 6 An inkjet-use metallic ink incorporating a metallic colloidal solution comprising: (a) metallic particles that (a1) are deposited by reducing metallic ions in water, (a2) have a primary-particle diameter of at most 200 nm, and (a3) made of a metal selected from the group consisting of nickel, copper, silver, gold, platinum, palladium, and an alloy of these metals; (b) a dispersant having a molecular weight of 200 to 30,000; and (c) a dispersion medium made of a mixed solvent of water and a water-soluble organic solvent, wherein the water-soluble organic solvent is one of a mixture of glycol ether and alcohol and a mixture of glycol ether and keton, and the ratio of the water-soluble organic solvent to the mixed solvent is at least 70 percent, but less than 100 percent by weight. ### Claim 7 (depends on 6) An inkjet-use metallic ink as defined by claim 6, the inkjet-use metallic ink having a surface tension of 20 to 60 mN/m at 25° C. and a viscosity of 0.5 to 40 mPa·s at 25° C. ### Claim 8 (depends on 6) An inkjet-use metallic ink as defined by claim 6, wherein the metallic colloidal solution is produced: (a) by using as a starting material a water-based metallic colloidal solution obtained by depositing metallic particles through the reduction of metallic ions in water; and (b) without undergoing a process that completely separates the metallic particles from water.