Microprecipitation process for dispersing photographic filter dyes

摘要

A process is provided for preparing microprecipitated dispersions of filter dyes by preparing a concentrated slurry in aqueous medium of a filter dye having ionizable acid sites on the dye molecule, adding sufficient aqueous hydroxide to dissolve the filter dye, acidifying the solution with a stoichiometric amount of acidic protons to reprotonate up to 100% of the total ionizable acid sites on the dye molecule and provide a microprecipitated dispersion of the filter dye that is insoluble in aqueous media at pH values less than 3 but soluble in aqueous media at pH greater than 10.