Ink jet inks and method of making

Claim 2

In a process for making water-based ink jet ink; the improvement comprising the sequential steps of: (1) formulating a diluted water-based concentrate of the ink formulation which is essentially free of agents known to inhibit particle formation and growth; (2) subjecting the concentrated ink to the operational stress of an elevated temperature of about 50° C. for a period of time sufficient to produce particle formation and growth; (3) filtering the concentrated ink to remove said particles; and (4) thereafter adding an aqueous vehicle a chelating agent and biocide to inhibit particle growth and formation from the final ink formulation.

Claim 3

The process of claim 1 including the step of formulating said diluted water-based concentrate with a purified and/or a presscake dye.

Claim 4

The process of claim 2 wherein said purified dye is nigrosine, and including the steps of making said purified nigrosine dye by solubilizing only the impurities in said dye in acid, filtering out the dye molecules, and recovering the dye molecules as purified nigrosine dye for use in the process of claim 2.

Claim 5

The process of claims 1, 2 or 3 including the additional step of filtering said final ink formulation to remove insoluble oils.

Claim 6

The process of claim 3 wherein the final ink formulation is a drop-on-demand formulation of the approximate composition ______________________________________ Weight % ______________________________________ Nigrosine dye 14.0 Polyethylene Glycol 20.0 Diethylene Glysol 20.0 N--Methyl-2-Pyrrolidone 8.0 Diethylene glycol monobutyl ether 8.0 Trisodium salt of N--hydroxy- ethylethylenediamine triacetic acid 0.5 Surfactant 0.4 Sodium-2-pyridinethiol-1-oxide 0.2 Ammonium Hydroxide 2.0 Water 27.4 ______________________________________ as compared to the diluted concentrate formulation of about ______________________________________ Weight % ______________________________________ Nigrosine dye 7.0 Polyethylene Glycol 10.0 Diethylene Glycol 10.0 N--Methyl Pyrrolidone 4.0 Diethylene glycol monobutyl ether 4.0 Tetramethyl decynediol 0.25 Surfactant 0.2 Sodium-2-pyridinethiol-1-oxide 0.1 Ammonium Hydroxide 1.0 Water 33.45 ______________________________________

Claim 7

The process of claim 3 wherein the final ink formulation is a continuous stream formulation of the approximate formulation ______________________________________ Weight % ______________________________________ Nigrosine Dye 7.0 Polyethylene Glycol 10.0 Diethylene Glycol 10.0 Butyl Carbitol 4.0 N--Methyl-2-Pyrrolidone 4.0 Tetramethyl decynediol 0.25 Surfactant 0.2 Trisodium salt of N--hydroxy- ethylethylenediamine triacetic acid 0.5 Sodium-2-pyridinethiol-1-oxide 0.1 Water 62.95 Ammonium Hydroxide 1.0 ______________________________________ as compared to the diluted concentrate formulation of about ______________________________________ Weight % ______________________________________ Nigrosine dye 7.0 Polyethylene Glycol 10.0 Diethylene Glycol 10.0 N--Methyl Pyrrolidone 4.0 Diethylene glycol monobutyl ether 4.0 Tetramethyl decynediol 0.25 Surfactant 0.2 Sodium-2-pyridinethiol-1-oxide 0.1 Ammonium Hydroxide 1.0 Water 33.45 ______________________________________