# US 10,246,599 B2 · Ink composition and method of determining a degree of curing of the ink composition > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,246,599 B2 - Document ID: US10246599B2 - Status: Granted - Kind: B2 - Application number: 14/216,366 - Filed: 2014-03-17 - Published: 2015-09-17 - Granted: 2019-04-02 - Earliest claimed: 2014-03-17 - Assignees: Xerox Corporation - Applicants: Xerox Corporation - Inventors: Naveen Chopra; Gabriel Iftime; Yiliang Wu; Sandra J. Gardner - Web page: https://patentgrep.com/patent/US10246599B2 ## CPC - C09D 11/52: Electrically conductive inks - C09D 11/037: characterised by the pigment - C09D 11/106: containing macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds - H01B 1/22: the conductive material comprising metals or alloys - 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}) ## Abstract A silver paste ink composition comprises a plurality of first particles comprising silver; a polymer binder; a carrier solvent; and a plurality of second particles comprising silver. The second particles are nanoparticles that are different than the first silver particles, the amount of second particles in the ink composition being sufficient to impart a first color to the uncured ink composition, the first color being different than the color of the same ink composition without the nanoparticles. The silver nanoparticles have a property of causing a change in the color of the ink composition when the ink composition is cured. ## Claims ### Claim 1 An uncured silver paste ink composition, comprising: a plurality of first particles comprising silver, the first particles being flakes and having a largest dimension with an average length ranging from about 2 microns to about 10 microns, the first particles being present in the silver paste ink composition in an amount ranging from 70% by weight to about 95% by weight, based on the total weight of the silver paste ink composition; a polymer binder comprising a thermoplastic material selected from the group consisting of a polyvinylbutyral terpolymer of a formula I and a mixture of the polyvinylbutyral terpolymer of formula I and polyvinylpyrrolidone, where R1 is a chemical bond or a divalent hydrocarbon linkage having from about 1 to about 20 carbons; R2 and R3 are independently an alkyl group, an aromatic group or a substituted aromatic group having from about 1 to about 20 carbon atoms; x, y and z represent the proportion of the corresponding repeat units respectively expressed as a weight percent, and the sum of x, y and z is about 100 weight percent; x is independently from about 3 weight percent to about 50 weight percent; y is independently from about 50 weight percent to about 95 weight percent; and z is independently from about 0.1 weight percent to about 15 weight percent, the polymer binder being in an amount ranging from 0.5 to 5 weight percent, based on the total weight of the silver paste ink composition; a carrier solvent; and a plurality of second particles comprising silver and having an average diameter ranging from about 3 nanometers to about 10 nanometers, the second particles being nanoparticles that are different than the first silver particles, the second particles in the ink composition being in an amount effective to impart a first color to the uncured silver paste ink composition, the first color being different than the color of the same ink composition without the nanoparticles, wherein the silver nanoparticles have a property of causing a change in the color of the ink composition when the ink composition is cured, the amount of second particles ranging from 3% by weight to about 20% by weight, relative to the total weight of the silver paste ink composition, wherein the plurality of second particles comprising silver are coated with an organic molecule stabilizer selected from the group consisting of octylamine, decylamine, dodecylamine, stearyl amine, octanoic acid, decanoic acid and stearic acid. ### Claim 2 (depends on 1) The composition of claim 1, wherein the uncured silver paste ink composition without the nanoparticles would be a color having a first lightness, L1; the nanoparticles impart a color having a second lightness, L2, to the uncured silver paste ink composition; and wherein if the ink composition were cured it would have a third lightness, L3, where L1, L2 and L3 are lightness values as defined in CIELAB color space, and further wherein L2 is less than both L1 and L3. ### Claim 3 (depends on 1) The composition of claim 1, wherein the concentration of second particles ranges from about 3% to about 10% by weight, relative to the total weight of the composition. ### Claim 4 (depends on 1) The composition of claim 1, wherein the concentration of carrier solvent ranges from about 5% to about 25% by weight, relative to the total weight of the composition. ### Claim 5 (depends on 1) The composition of claim 1, wherein R1 is a bond, R2 is a 3 carbon alkyl group, and R3 is a 1 carbon atom alkyl group. ### Claim 6 (depends on 5) The composition of claim 5, wherein the solvent is Di(ethylene glycol) monobutyl ether. ### Claim 7 (depends on 5) The composition of claim 5, wherein the solvent is a glycol ether. ### Claim 8 (depends on 1) The composition of claim 1, wherein the polyvinylbutyral terpolymer has a weight average molecular weight of about 10,000 to about 600,000 Daltons. ### Claim 9 (depends on 1) The composition of claim 1, wherein the polyvinylbutyral terpolymer has a glass transition temperature (“Tg”) of from about 60° C. to about 100° C. ### Claim 10 (depends on 1) The composition of claim 1, wherein the polymer binder is the mixture of polyvinylbutyral terpolymer of formula I and polyvinylpyrrolidone. ### Claim 11 (depends on 10) The composition of claim 10, wherein the polyvinylpyrrolidone has a weight average molecular weight of about 5,000 to about 80,000 Daltons. ### Claim 12 (depends on 10) The composition of claim 10, wherein the polyvinylpyrrolidone has a glass transition temperature (“Tg”) of from 125° C. to 180° C. ### Claim 13 (depends on 1) A method of determining a degree of curing of a silver paste ink, the method comprising: providing the uncured silver paste ink composition of claim 1; coating the silver paste ink composition onto a substrate; heating the silver paste ink composition to a temperature and for a length of time sufficient to cure the composition, wherein the ink has a first color prior to heating and has a second color when curing is complete, the second color being different than the first color; and visually inspecting the silver paste ink composition to determine whether the color change indicates that curing is complete. ### Claim 14 (depends on 13) The method of claim 13, wherein the coating comprises screen printing the silver paste ink. ### Claim 15 (depends on 13) The method of claim 13, wherein the first color has a lightness, L2, and the second color has a lightness, L3, wherein L2 and L3 are lightness values as defined in CIELAB color space, and further wherein L2 is less than L3. ### Claim 16 (depends on 13) The method of claim 13, wherein the curing temperature ranges from about 80° to about 200° C.