Process for preparing ink compositions for ink-jet printer

Abstract From the Canadian patent

A process for preparing an aqueous-based ink composition for use in ink-Jet printers is disclosed. The process comprises (a) forming a solution of a dye having at least one negatively charged functional group per molecule; (b) acidifying the solution; (c) cycling the solution through a reverse osmosis membrane to form a concentrate and a permeate, the concentrate including a cation of the compound associated with at least one functional group on the dye and the permeate including a cation formerly associated with at least one funtional group; (a) adding water as necessary; (e) concentrating the dye by reverse osmosis; and (f) admixing the concentrated aye with at least one glycol etner. The …