# US 5,350,446 A · Hot melt impulse ink jet ink with dispersed solid pigment in a hot melt vehicle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,350,446 A - Document ID: US5350446A - Status: Granted - Kind: A - Application number: 08/110,481 - Filed: 1993-08-20 - Granted: 1994-09-27 - Earliest claimed: 1984-11-05 - Assignees: Dataproducts Corporation - Inventors: An-Chung R. Lin; Theodore M. Cooke - Web page: https://patentgrep.com/patent/US5350446A ## CPC - C09D 11/34: Hot-melt inks - 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 A novel hot melt ink jet ink is disclosed for use in an impulse ink jet apparatus. The disclosed ink comprises a dispersed solid pigment which is formulated in a wax, or high molecular weight fatty acid or alcohol vehicle to form a hot melt ink which is solid at room temperature. The provision of such a pigment containing ink provides a high quality ink which is stable for long periods of time at relatively high temperatures. In the preferred embodiments, a dispersed graphite in a non-evaporative oil carrier, such as mineral oil, is formulated with candelilla wax, stearic acid and/or behenic acid. ## Claims ### Claim 1 A hot melt solid ink for supply to an ink jet apparatus which heats the solid ink to an elevated jetting temperature and supplies it as liquid ink to an impulse ink jet of a small nozzle diameter, said hot melt solid ink comprising: a vehicle selected from the group consisting of (i) a wax having a melting temperature above 65.degree. C. and (ii) a C.sub.18 -C.sub.24 fatty acid or alcohol; solid pigment as a recording means in an amount of no more than 10 percent of the total weight of said ink and having a particle size sufficiently small so as not to clog the nozzle and so as to minimize the terminal settling velocity of the solid pigment; a non-evaporative carrier in which the solid pigment is suspended, the carrier being dispersed through the vehicle and compatible with the vehicle to enable the carrier and pigment to remain dispersed within the vehicle for long periods even at the jetting temperature and to enable the more efficient use of a smaller amount of said solid pigment; and said hot melt ink having a jetting viscosity of no more than 15 cP at the jetting temperature. ### Claim 2 (depends on 1) The ink of claim 1 wherein the carrier is an oil carrier. ### Claim 3 (depends on 1) The ink of claim 1 wherein the carrier is mineral oil. ### Claim 4 (depends on 1) The ink of claim 1 wherein the solid pigment is colloidal graphite. ### Claim 5 (depends on 1) The ink of claim 1 wherein the nozzle diameter is 5-75 microns and the particle size of the solid pigment is less than 25 microns. ### Claim 6 (depends on 1) The ink of claim 1 wherein the elevated jetting temperature is above 65.degree. C. ### Claim 7 (depends on 1) The ink of claim 1 wherein the elevated jetting temperature is above 80.degree. C. ### Claim 8 (depends on 1) The ink of claim 1 wherein the elevated jetting temperature is above 80.degree. C. and the jetting viscosity is no more than 14 cp. ### Claim 9 (depends on 1) The ink of claim 1 wherein the vehicle is candelilla wax. ### Claim 10 (depends on 1) The ink of claim 1 wherein the vehicle is stearic acid behenic acid, and their mixtures. ### Claim 11 (depends on 1) The ink of claim 1 wherein the ink includes a ketone having a melting point between 65.degree.-120.degree. C. ### Claim 12 (depends on 11) The ink of claim 11 wherein the ketone is stearone. ### Claim 13 (depends on 1) The ink of claim 1, wherein the solid pigment is barium lithol. ### Claim 14 (depends on 1) The ink of claim 1, wherein the solid pigment is carbon black. ### Claim 15 (depends on 1) The ink of claim 1, wherein the solid pigment comprises about 0.1-10 by weight percent of the ink. ### Claim 16 (depends on 1) The ink of claim 1, wherein the solid pigment comprises about 1-5 by weight percent of the ink. ### Claim 17 (depends on 1) The ink of claim 1, wherein the solid pigment comprises about 2-3 by weight percent of the ink. ### Claim 18 (depends on 1) The ink of claim 1, wherein the solid pigment comprises an average particle size of less than 10 microns. ### Claim 19 (depends on 1) The ink of claim 1, wherein the solid pigment comprises an average particle size of less than 1 micron. ### Claim 20 (depends on 1) The ink of claim 1, wherein the vehicle comprises about 50-99.1 by weight percent of the ink. ### Claim 21 (depends on 1) The ink of claim 1, wherein the vehicle comprises about 90-99 by weight percent of the ink. ### Claim 22 (depends on 1) The ink of claim 1, wherein the vehicle comprises about 95-98 by weight percent of the ink. ### Claim 23 (depends on 1) The ink of claim 1, wherein the ink further includes a plasticizer. ### Claim 24 (depends on 11) The ink of claim 11, wherein the ketone is laurone. ### Claim 25 (depends on 11) The ink of claim 11, wherein the ketone is less than 50 weight percent of the ink. ### Claim 26 A method of operating an ink jet apparatus of a small nozzle diameter, comprising the steps of: (a) heating a hot melt solid ink comprising: a vehicle selected from the group consisting of: (i) a wax having a melting temperature above 65.degree. C. and (ii) a C.sub.18 -C.sub.24 fatty acid or alcohol, and a non-evaporative carrier in which a solid pigment, suspended in the carrier, in an amount of no more than 10 percent of the total weight of said ink and having a particle size much smaller than nozzle diameter so as not to clog the nozzle and sufficiently small so as to minimize the terminal settling velocity of the solid pigment, the carrier being dispersed through the vehicle and compatible with the vehicle and thus enables the more efficient use of a smaller amount of said pigment; (b) during a printing period discharging droplets of the liquid ink via an impulse ink jet into a nearby print substrate; and (c) during a standby period maintaining the liquid ink at the elevated temperature in readiness for the next printing period without the pigment settling out or separating from the vehicle. ### Claim 27 (depends on 26) The method of claim 26 wherein the carrier is an oil carrier. ### Claim 28 (depends on 26) The method of claim 26 wherein the carrier is mineral oil. ### Claim 29 (depends on 26) The method of claim 26 wherein the solid pigment is colloidal graphite. ### Claim 30 (depends on 26) The method of claim 26 wherein the nozzle diameter is 50-75 microns and the particle size of the pigment is less than 25 microns. ### Claim 31 (depends on 26) The method of claim 26 wherein the jetting temperature is above 65.degree. C. ### Claim 32 (depends on 26) The method of claim 26 wherein the jetting temperature is above 80.degree. C. ### Claim 33 (depends on 26) The method of claim 26 wherein the jetting temperature is above 80.degree. C. and the jettable viscosity is no more than 14 cp. ### Claim 34 (depends on 26) The method of claim 26 wherein the solid pigment is 0.1-5% by weight of the ink. ### Claim 35 (depends on 26) The method of claim 26 wherein the vehicle is candelilla wax. ### Claim 36 (depends on 26) The method of claim 26 wherein the vehicle is selected from the group consisting of stearic acid, behenic acid, and their mixtures. ### Claim 37 (depends on 26) The method of claim 26 wherein the ink includes a ketone having a melting point between 65.degree.-120.degree. C. ### Claim 38 (depends on 37) The method of claim 37 wherein the ketone is stearone. ### Claim 39 A hot melt solid ink for supplying to an ink jet apparatus which heats the solid ink to an elevated jetting temperature and supplies it as liquid ink to an impulse ink jet of a small nozzle diameter, said hot melt solid ink comprising: a vehicle selected from the group consisting of (i) a wax having a melting temperature above 65.degree. C. and (ii) a C.sub.18 -C.sub.24 fatty acid or alcohol; solid pigment as a recording means, having a particle size of no greater than 10 microns and in an amount of no more than 10 percent of the total weight of said ink; a non-evaporative carrier in which the solid pigment is suspended, and the carrier being dispersed through the vehicle and compatible with the vehicle to enable the carrier and pigment to remain dispersed within the vehicle for long periods even at the jetting temperature and to enable the more efficient use of a smaller amount of said solid pigment; and said hot melt ink having a jetting viscosity of no more than 15 cP at the jetting temperature not to exceed 110.degree. C. ### Claim 40 A method of operating an ink jet apparatus of a small nozzle diameter, comprising the steps of: (a) heating a hot melt solid ink having a viscosity of no more than 15 cP at a jetting temperature of not to exceed 110.degree. C., comprising: a vehicle selected from the group consisting of: (i) a wax having a melting temperature above 65.degree. C. and (ii) a C.sub.18 -C.sub.24 fatty acid or alcohol, and a non-evaporative carrier, a solid pigment, suspended in the carrier, of a particle size of no greater than 10 microns and in an amount of no more than 10 percent of the total weight of said ink, the carrier being dispersed through the vehicle and compatible with the vehicle and thus enables the more efficient use of a smaller amount of said solid pigment; (b) during a printing period discharging droplets of the liquid ink via an impulse ink jet onto a nearby print substrate; and (c) during a standby period maintaining the liquid ink at the jetting temperature in readiness for the next printing period without the pigment settling out or separating from the vehicle.