Patent ID: 8486306

Claim:
An ink comprising: a dispersion medium, a coupling agent, and metallic particles consisting of nickel particles, the dispersion medium comprising a main solvent, a surface tension modifier and a viscosity modifier, wherein: the main solvent consists essentially of a glycol having a boiling point of 300° C. or lower at atmospheric pressure, and a viscosity of 100 cP or lower at ambient temperature, the surface tension modifier consists essentially of an alcohol having a boiling point of 100° C. to 300° C. at atmospheric pressure and a surface tension of 20 to 34 mN/m at 25° C., the viscosity modifier consists essentially of a ketone having a boiling point of 100° C. to 300° C. at atmospheric pressure, and a weight ratio of the surface tension modifier to the main solvent is in a range of 0.1 to 0.5 and a weight ratio of the viscosity modifier to the main solvent is in the range of 0.1 to 1.2, the coupling agent comprises one member or a combination of two or more members selected from the group consisting of a silane coupling agent, a titanium coupling agent, a zirconia coupling agent and an aluminum coupling agent, the metallic particles consisting of nickel particles have an average primary particle size of 50 nm or smaller, the weight ratio of the coupling agent to the nickel particles is in a range of from 0.05 to 0.6, and the ink has a surface tension in a range of 15 to 50 mN/m and a viscosity at 25° C. of 60 cP or lower such that the ink is used for inkjet printing.