US Patent 7842102 Liquid dye formulations in non-petroleum based solvent systems

A dye formulation is disclosed that includes a vegetable oil ester based solvents that have carbon chain lengths of C-1 to C-18, a solvent dye that is a true liquid dye dissolved in the vegetable oil ester for imparting color to the dye formulation, and reduced sulfur levels in commercially available dye formulations as compared to those in hydrocarbon based solvent systems. Sulfur content is typically reduced to 2-3 percent of dye formulations in hydrocarbon based solvents. The formulations are particularly useful for tagging petroleum substrates as well as writing instrument and ink jet formulations.