PIGMENT INK FORMULATION

摘要

The invention provides an improved ink formulation and method therefore. The formulation includes from about 50 to about 85 percent by weight water, humectant and an organic solvent and a chemically modified carbon black pigment, wherein the chemically modified carbon black pigment contains steric inducing groups on a surface of the carbon black which groups are derived from a steric inducing compound which compound is substantially soluble in the humectant and is reactive with an organic acid halide. The ink jet printer ink formulation containing the chemically modified carbon black has an idle time of greater than about 15 seconds in an ink jet printhead. Improved idle time is important because it reduces nozzle plugging between nozzle firings.