Improved ink compositions for thermal ink jet printing

Abstract: Disclosed is an ink composition which comprises (a) water, (b) a colorant, and (c) a material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ], wherein X is a cation and n is an integer of from about 3 to about 20. Also disclosed are processes for preparing the ink composition and ink jet printing processes with the ink composition.

Description: The present invention is directed to ink compositions and to processes for the use thereof. More specifically, the present invention is directed to compositions suitable for use in ink jet printing processes. One embodiment of the present invention is directed to an ink composition which comprises (a) water, (b) a colorant, and (c) a material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ], wherein X is a cation and n is an integer of from 3 to 20. U.S. Patent 5,019,166 discloses a thermal ink jet printing composition comprising a dye, a liquid medium, and a surfactant selected from the group consisting of polyoxyalkylated ethers, anionic bitail fluorothio alkyls, alkyl aryl sulfonates, alkyl amine quaternary salts, and mixtures thereof. Also disclosed is a process for generating images which comprises causing the ink compositions disclosed herein to be ejected from a thermal ink jet printer in imagewise fashion onto a substrate. U.S. Patent 5,401,303 discloses a process wherein the halo effect seen at the interface between a first ink, exhibiting sharp edge acuity, and a second ink, having low surface energy, is addressed by adding certain fluorocarbon compounds to the first ink. Edge acuity of the first ink is maintained. While known compositions and processes are suitable for their intended purposes, a need remains for improved ink compositions suitable for use in thermal ink jet printing processes. In addition, a need remains for ink compositions which exhibit improved shelf stability at pH values below 9.0. Further, a need remains for ink compositions which exhibit improved viscosity stability with respect to pH and temperature. Additionally, a need remains for ink compositions with reduced viscosity. There is also a need for ink compositions with improved jetting characteristics. In addition, there is a need for ink compositions which can be prepared rapidly. Further, there is a need for ink compositions which exhibit improved filtration characteristics. Additionally, there is a need for ink compositions that exhibit reduced intercolor bleed when inks of different colors are printed in adjacent areas. A need further remains for ink compositions for which a wide variety of colorants are suitable and compatible with the ink ingredients. In addition, a need remains for ink compositions with surface tension values of greater than 25 dynes per centimeter. Further, a need remains for ink compositions with improved wetting characteristics. Additionally, a need remains for ink compositions which exhibit improved recoverability characteristics in ink jet printers. There is also a need for ink compositions which enable a wide color gamut. In addition, there is a need for ink compositions which enable prints with reduced curl when the inks are printed onto substrates such as paper. Further, there is a need for ink compositions which enable prints with improved transparency transmission and improved wetting characteristics when the inks are printed onto transparent substrates. Additionally, there is a need for ink compositions with improved latency characteristics. A need additionally remains for ink compositions which exhibit reduced showthrough when printed on paper. Further, a need remains for ink compositions which are suitable for printing on a wide variety of substrates. In addition, a need remains for ink compositions which remain homogeneous over extended periods of time. Further, a need remains for ink compositions which exhibit further improvements in intercolor bleed characteristics when prints generated therewith are subjected to drying-assisting processes such as heating, microwave drying, or the like. It is an object of the present invention to provide ink compositions with the above noted advantages. The present invention provides an ink composition which comprises (a) a colorant, and (b) a liquid vehicle which comprises (i) water, and (ii) a fluorinated material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ], wherein X is a cation and n is an integer of from 3 to 20. Specific embodiments of the present invention are set forth in the claims. Preferred embodiments of the present invention include: (1) An ink composition as specified above wherein the colorant is an anionic dye and wherein the ink also contains imidazole, said ink containing water in an amount of from 68.4 to 89.1 percent by weight of the ink, imidazole in an amount of from 10.4 to 20.7 percent by weight of the ink, and the fluorinated material in an amount of from 0.31 to 0.62 percent by weight of the ink; (2) An ink composition as specified above wherein the colorant is an anionic dye and wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 0.01 to 65 percent by weight of the liquid vehicle, imidazole in an amount of from 15 to 75 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 9 percent by weight of the liquid vehicle; (3) An ink composition as specified above wherein the colorant is an anionic dye and wherein the ink also contains imidazole and citric acid and has a pH of from 8.7 to 8.8, said ink containing water in an amount of from 62 to 80 percent by weight of the ink, imidazole in an amount of from 17 to 21 percent by weight of the ink, citric acid in an amount of from 0.8 to 1.1 percent by weight of the ink, and the fluorinated material in an amount of from 0.015 to 0.41 percent by weight of the ink; (4) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 0.01 to 75 percent by weight of the liquid vehicle, imidazole in an amount of from 25 to 65 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 6.75 percent by weight of the liquid vehicle, and wherein said ink also contains citric acid; (5) An ink composition as specified above wherein the colorant is an anionic dye and wherein the ink also contains imidazole, betaine, and citric acid and has a pH of from 8.7 to 8.8, said ink containing water in an amount of from about 62 to 71 percent by weight of the ink, imidazole in an amount of from 1 to 4 percent by weight of the ink, betaine in an amount of about 15 percent by weight of the ink, citric acid in an amount of from 0.06 to 0.2 percent by weight of the ink, and the fluorinated material in an amount of from 0.015 to 0.2 percent by weight of the ink; (6) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 0.01 to 80 percent by weight of the liquid vehicle, imidazole in an amount of from 0.01 to 80 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 5.25 percent by weight of the liquid vehicle, and wherein said ink also contains citric acid and betaine; (7) An ink composition as specified above wherein the colorant is an anionic dye and wherein the ink also contains imidazole, cyclohexylpyrrolidinone, and citric acid, said ink containing water in an amount of from 60 to 74 percent by weight of the ink, imidazole in an amount of from 13 to 21 percent by weight of the ink, cyclohexylpyrrolidinone in an amount of about 2 percent by weight of the ink, citric acid in an amount of about 1 percent by weight of the ink, and the fluorinated material in an amount of from 0.15 to 0.30 percent by weight of the ink; (8) An ink composition as specified above wherein the colorant is an anionic dye and wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 35 to 70 percent by weight of the liquid vehicle, imidazole in an amount of from 20 to 50 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 4.5 percent by weight of the liquid vehicle, and wherein said ink also contains citric acid and cyclohexylpyrrolidinone; (9) An ink composition as specified above wherein the colorant is an anionic dye and wherein the ink also contains imidazole, cyclohexylpyrrolidinone, and citric acid and has a pH of from 8.7 to 8.8, said ink containing water in an amount of from 61 to 68 percent by weight of the ink, imidazole in an amount of from 17 to 24 percent by weight of the ink, cyclohexylpyrrolidinone in an amount of about 2 percent by weight of the ink, citric acid in an amount of from 0.8 to 1.2 percent by weight of the ink, and the fluorinated material in an amount of from 0.15 to 0.39 percent by weight of the ink; (10) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 15 to 20 percent by weight of the liquid vehicle, imidazole in an amount of from 25 to 65 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 3 percent by weight of the liquid vehicle, and wherein said ink also contains cyclohexylpyrrolidinone and citric acid; (11) An ink composition as specified above wherein the colorant is an anionic dye and wherein the ink also contains imidazole, cyclohexylpyrrolidinone, and citric acid and has a pH of from 8.2 to 8.3, said ink containing water in an amount of from 51 to 55 percent by weight of the ink, imidazole in an amount of from 1.4 to 4.8 percent by weight of the ink, cyclohexylpyrrolidinone in an amount of about 2 percent by weight of the ink, citric acid in an amount of from 0.07 to 0.24 percent by weight of the ink, and the fluorinated material in an amount of from 1 to 2.6 percent by weight of the ink; (12) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.2 to 8.3, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 65 to 80 percent by weight of the liquid vehicle, imidazole in an amount of from 2 to 25 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 3.8 percent by weight of the liquid vehicle, and wherein said ink also contains cyclohexylpyrrolidinone and citric acid; (13) An ink composition as specified above wherein the colorant is an anionic dye and wherein the ink also contains imidazole, an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000, and citric acid and has a pH of from 8.7 to 8.8, said ink containing water in an amount of from 79 to 83 percent by weight of the ink, imidazole in an amount of from 1.4 to 4.9 percent by weight of the ink, the polymer in an amount of about 0.1 percent by weight of the ink, citric acid in an amount of from 0.07 to 0.25 percent by weight of the ink, and the fluorinated material in an amount of from 0.015 to 0.24 percent by weight of the ink; (14) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 25 to 55 percent by weight of the liquid vehicle, imidazole in an amount of from 25 to 55 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 2.25 to 5.25 percent by weight of the liquid vehicle, and wherein said ink also contains an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000 and citric acid; (15) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 75 to 80 percent by weight of the liquid vehicle, imidazole in an amount of from 2 to 7 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 2.25 percent by weight of the liquid vehicle, and wherein said ink also contains an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000 and citric acid; (16) An ink composition as specified above wherein the colorant is an anionic dye and wherein the ink also contains imidazole, betaine, cyclohexylpyrrolidinone, and citric acid and has a pH of from 8.7 to 8.8, said ink containing water in an amount of from 61 to 69 percent by weight of the ink, imidazole in an amount of from about 1 to about 3.7 percent by weight of the ink, betaine in an amount of about 15 percent by weight of the ink, cyclohexylpyrrolidinone in an amount of about 2 percent by weight of the ink, citric acid in an amount of from 0.05 to 0.19 percent by weight of the ink, and the fluorinated material in an amount of from 0.12 to 0.56 percent by weight of the ink; (17) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 0.01 to 80 percent by weight of the liquid vehicle, imidazole in an amount of from 0.01 to 80 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 3.75 percent by weight of the liquid vehicle, and wherein said ink also contains betaine, cyclohexylpyrrolidinone, and citric acid; (18) An ink composition as specified above wherein the colorant is an anionic dye and wherein the ink also contains imidazole, betaine, an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000, and citric acid and has a pH of from 8.7 to 8.8, said ink containing water in an amount of from 50 to 52 percent by weight of the ink, imidazole in an amount of from 1 to 8 percent by weight of the ink, betaine in an amount of about 15 percent by weight of the ink, the polymer in an amount of about 0.1 percent by weight of the ink, citric acid in an amount of from 0.06 to 0.4 percent by weight of the ink, and the fluorinated material in an amount of from 0.01 to 0.32 percent by weight of the ink; (19) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 65 to 80 percent by weight of the liquid vehicle, imidazole in an amount of from 2 to 25 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 3.75 percent by weight of the liquid vehicle, and wherein said ink also contains betaine, an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000, and citric acid; (20) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 5 to 55 percent by weight of the liquid vehicle, imidazole in an amount of from 35 to 75 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 5.25 percent by weight of the liquid vehicle, and wherein said ink also contains betaine, an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000, and citric acid; (21) An ink composition as specified above wherein the colorant is an anionic dye and wherein the ink also contains imidazole, cyclohexylpyrrolidinone, an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000, and citric acid and has a pH of from 8.7 to 8.8, said ink containing water in an amount of from 78 to 81 percent by weight of the ink, imidazole in an amount of from 0.7 to 17 percent by weight of the ink, cyclohexylpyrrolidinone in an amount of about 2 percent by weight of the ink, the polymer in an amount of about 0.1 percent by weight of the ink, citric acid in an amount of from about 0.035 to 0.85 percent by weight of the ink, and the fluorinated material in an amount of from 0.03 to 0.11 percent by weight of the ink; (22) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 65 to 80 percent by weight of the liquid vehicle, imidazole in an amount of from 2 to 25 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 3.75 percent by weight of the liquid vehicle, and wherein said ink also contains cyclohexylpyrrolidinone, an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000, and citric acid; (23) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 5 to 55 percent by weight of the liquid vehicle, imidazole in an amount of from about 5 to about 65 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 11.25 percent by weight of the liquid vehicle, and wherein said ink also contains cyclohexylpyrrolidinone, an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000, and citric acid; (24) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 5 to 15 percent by weight of the liquid vehicle, imidazole in an amount of from 2 to 12 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 11.25 to 12 percent by weight of the liquid vehicle, and wherein said ink also contains cyclohexylpyrrolidinone, an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000, and citric acid; (25) An ink composition as specified above wherein the colorant is an anionic dye and wherein the ink also contains imidazole, betaine, cyclohexylpyrrolidinone, an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000, and citric acid and has a pH of from 8.7 to 8.8, said ink containing water in an amount of from 78 to 81 percent by weight of the ink, imidazole in an amount of from 0.7 to 17 percent by weight of the ink, betaine in an amount of about 15 percent by weight of the ink, cyclohexylpyrrolidinone in an amount of about 2 percent by weight of the ink, the polymer in an amount of about 0.1 percent by weight of the ink, citric acid in an amount of from 0.035 to 0.85 percent by weight of the ink, and the fluorinated material in an amount of from 0.21 to 0.71 percent by weight of the ink; (26) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 65 to 80 percent by weight of the liquid vehicle, imidazole in an amount of from 2 to 25 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 3.75 percent by weight of the liquid vehicle, and wherein said ink also contains betaine, cyclohexylpyrrolidinone, an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000, and citric acid; (27) An ink composition as specified above wherein the colorant is an anionic dye, wherein the ink has a pH of from 8.7 to 8.8, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 5 to 65 percent by weight of the liquid vehicle, imidazole in an amount of from 25 to 75 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 8.25 percent by weight of the liquid vehicle, and wherein said ink also contains betaine, cyclohexylpyrrolidinone, an ethoxylated 2-naphthol polymer with a molecular weight of about 27,000, and citric acid; (28) An ink composition as specified above wherein the colorant is an anionic dye, wherein the liquid vehicle further contains imidazole, said liquid vehicle containing water in an amount of from 0.01 to 65 percent by weight of the liquid vehicle, imidazole in an amount of from 15 to 75 percent by weight of the liquid vehicle, and the fluorinated material in an amount of from 0.15 to 9 percent by weight of the liquid vehicle, and wherein said ink also contains citric acid; and (29) An ink composition as specified above further containing liquid crystals. Inks of the present invention contain an aqueous liquid vehicle. The liquid vehicle can consist solely of water, or it can comprise a mixture of water and a water soluble or water miscible organic component, such as ethylene glycol, propylene glycol, diethylene glycols, glycerine, dipropylene glycols, polyethylene glycols, polypropylene glycols, tripropylene glycol monomethyl ether, amides, ethers, urea, substituted ureas, ethers, carboxylic acids and their salts, esters, alcohols, organosulfides, organosulfoxides, sulfones (such as sulfolane), alcohol derivatives, carbitol, butyl carbitol, cellusolve, ether derivatives, amino alcohols, ketones, N-methylpyrrolidinone, 2-pyrrolidinone, cyclohexylpyrrolidone, hydroxyethers, amides, sulfoxides, lactones, polyelectrolytes, methyl sulfonylethanol, imidazole, betaine, and other water soluble or water miscible materials, as well as mixtures thereof. When mixtures of water and water soluble or miscible organic liquids are selected as the liquid vehicle, the water to organic ratio typically ranges from about 100:0 to 30:70, and preferably from 97:3 to 40:60. The non-water component of the liquid vehicle generally serves as a humectant which has a boiling point higher than that of water (100°C). In the ink compositions of the present invention, the liquid vehicle is typically present in an amount of from 80 to about 99.9 percent by weight of the ink, and preferably from about 90 to about 99 percent by weight of the ink, although the amount can be outside these ranges. Also contained in the ink composition of the present invention is a colorant. Any suitable colorant can be employed, including dyes, pigments, and mixtures thereof. Suitable dye or mixture of dyes compatible with the ink liquid vehicle include acid dyes, direct dyes, and reactive dyes, with water soluble anionic dyes being preferred. The dye is present in the ink composition in any effective amount, typically from 0.5 to 15 percent by weight of the ink, and preferably from 11 to 10 percent by weight of the ink, although the amount can be outside of these ranges. Examples of suitable pigments for the inks of the present invention include various carbon blacks such as channel black, furnace black, and lamp black. Colored pigments include red, green, blue, brown, magenta, cyan, and yellow particles, as well as mixtures thereof. Preferably, the pigment particle size is as small as possible to enable a stable colloidal suspension of the particles in the liquid vehicle and to prevent clogging of the ink channels when the ink is used in a thermal ink jet printer. Preferred particle average diameters are generally from 0.001 to 5 microns, and more preferably from 0.1 to 1 micron, although the particle size can be outside these ranges. Within the ink compositions of the present invention, the pigment is present in any effective amount to achieve the desired degree of coloration. Typically, the pigment is present in an amount of from 0.1 to 8 percent by weight of the ink, and preferably from 2 to 7 percent by weight of the ink, although the amount can be outside these ranges. Also contained in the ink is a material of the formula wherein X + is a cation and n is an integer of from 3 to 20, preferably from 4 to 15, and more preferably from 5 to 11. Examples of suitable cations include ammonium, (HO-CH 2 CH 2 ) 2 NH 2 + , (HO-CH 2 CH 2 ) 3 NH + , (HO-CH 2 CH 2 )NH 3 + , an imidazolium cation such as imidazolium, N-methyl imidazolium, or N-butyl imidazolium, tris(hydroxymethyl)aminomethane hydrochloride, tris(hydroxymethyl)aminomethane hydrocitrate, and protonated 1,4-diazabicyclo[2.2.2]octane. Materials of this formula are available from, for example, Ciba-Geigy, Ardsley, New York (Greensboro, NC) as LODYNE P-502, containing a mixture of compounds wherein n has varying values and has an average value of about 9. The fluorinated material is present in the ink in any effective or desired amount; typically, the amount ranges from 0.1 to 10 percent by weight of the ink, preferably from 0.25 to 6 percent by weight of the ink, more preferably from 0.5 to 5 percent by weight of the ink, and even more preferably from 1 to 4 percent by weight of the ink, although the amount can be outside these ranges. In one preferred embodiment of the present invention, the fluorinated material is of the formula wherein n is 5. This material is available from, for example, Ciba-Geigy, Ardsley, New York (Greensboro, NC) as LODYNE P-502L, containing the fluorocarbon wherein substantially all of the material has exactly 6 carbon atoms in each of the fluorinated hydrocarbon chains. Inks containing this material exhibit improved shelf stability, even when the fluorocarbon and/or the ink are not subjected to ultrasonification or high shear mixing. These materials also exhibit good shelf stability with a wide variety of dyes, whereas inks containing mixtures of fluorocarbons of the above formula wherein n has varying values may be compatible with some dyes and may exhibit reduced shelf stability with other dyes. The ink fabrication process is accordingly simplified, with no need for procedures other than simple mixing of the ingredients to obtain optimal performance. In one embodiment, the ink also contains another fluorocarbon material of the formula wherein n is an integer of from 8 to 20 and B is a cation. In one specific embodiment, n is 10 and B is (HO-CH 2 CH 2 ) 2 NH 2 + . Other examples of suitable cations include ammonium, (HO-CH 2 CH 2 ) 3 NH + , (HO-CH 2 CH 2 )NH 3 + , an imidazolium cation such as imidazolium, N-methyl imidazolium, or N-butyl imidazolium, tris(hydroxymethyl)aminomethane hydrochloride, tris(hydroxymethyl)aminomethane hydrocitrate, and protonated 1,4-diazabicyclo[2.2.2]octane. Materials of this formula are available from, for example, Ciba-Geigy, Ardsley, New York (Greensboro, NC) as LODYNE P-201. In this embodiment, the fluorocarbon mixture in the ink comprises the fluorinated material of the formula [(F 2n+1 C n CH 2 S) 2 (CH 3 )C-CH 2 CH 2 COO - ][B + ] wherein n is an integer of from 8 to 20 and B is a cation in an amount of from 75 to 95 percent by weight of the fluorocarbon mixture, preferably in an amount of from 85 to 93 percent by weight of the fluorocarbon mixture, and more preferably in an amount of about 90 percent by weight of the fluorocarbon mixture, and the fluorinated material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ] wherein X + is a cation and n is an integer of from 3 to 20 in an amount of from 5 to 25 percent by weight of the fluorocarbon mixture, preferably in an amount of from 7 to 15 percent by weight of the fluorocarbon mixture, and more preferably in an amount of about 10 percent by weight of the fluorocarbon mixture, although the relative amounts of each fluorocarbon with respect to the other can be outside these ranges. In this embodiment, the total amount of fluorocarbon in the ink typically is from 0.1 to 6 percent by weight of the ink, and preferably from 2 to 4 percent by weight of the ink, although the amount can be outside of these ranges. While not being limited to any particular theory, it is believed that when ink compositions contain a fluorocarbon mixture comprising a major amount of a fluorinated material of the formula [(F 2n+1 C n CH 2 S) 2 (CH 3 )C-CH 2 CH 2 COO - ][B + ] and a minor amount of a fluorinated material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ], the size of liposomes formed in the ink is reduced, thereby improving shelf stability of the ink. In another specific embodiment of the present invention, the ink comprises water, a colorant, a material of the formula wherein X + is a cation and n is an integer of from 3 to 20, and a penetrant material selected from betaine, cyclohexyl pyrrolidinone, butyl carbitol (diethylene glycol monobutyl ether), tripropylene glycol monomethyl ether, or mixtures thereof. The penetrant material is present in any effective or desired amount, typically from 0.1 to 20 percent by weight, and preferably from 3 to 15 percent by weight, although the amount can be outside these ranges. Inks of this specific embodiment are preferred over those containing a surfactant because of frequently reduced viscosity. The ink compositions are generally of a viscosity suitable for use in thermal ink jet printing processes. At room temperature (i.e., about 25°C), typically, the ink viscosity is no more than 10 centipoise, and preferably is from 1 to 5 centipoise, more preferably from 1 to 4 centipoise, although the viscosity can be outside this range. Ink compositions of the present invention can be of any suitable or desired pH. For some embodiments, such as thermal ink jet printing processes, typical pH values are from 7.75 to 9.25, and preferably from 8.25 to 8.75, although the pH can be outside of these ranges. The present invention further provides a process for preparing an ink composition which comprises (i) subjecting a composition comprising a material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ], wherein X is a cation and n is an integer of from 3 to 20 to ultrasonification; and (ii) admixing colorant with the composition, thereby forming an ink, said ink composition further containing water. In a preferred embodiment, water is admixed with the material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ] in step (i). In another preferred embodiment, water is admixed with the material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ] and the colorant in step (ii). In one specific embodiment, the ink is subjected to ultrasonification to reduce the particle size of the liposomes in the ink formed by the fluorocarbon material. In this embodiment, the ink is subjected to ultrasonication at relatively low intensity, typically for from 5 to 90 minutes, preferably from about 10 to 60 minutes, and in a preferred embodiment for about 20 minutes. In another specific embodiment of the present invention, the fluorocarbon material is subjected to ultrasonification prior to admixing it with the other ink ingredients. in this second embodiment, the fluorocarbon can be ultrasonicated either in the form in which it is received from the supplier (assuming said form is a liquid containing the fluorocarbon) or after admixing it with water, mixtures of water and one or more desired buffering components, or mixtures of water and one or more other desired ink components. In a particularly preferred embodiment, the ultrasonicated liquid contains the fluorocarbon material in an amount of about 15 percent by weight and water in an amount of about 85 percent by weight. In another particularly preferred embodiment, the ultrasonicated liquid contains the fluorocarbon material in an amount of about 15 percent by weight, 1,4-diazabicyclo[2.2.2]octane in an amount of about 20 percent by weight, and water in an amount of about 65 percent by weight. In another particularly preferred embodiment, the ultrasonicated liquid contains the fluorocarbon material in an amount of from 9 to 10 percent by weight, 1,4-diazabicyclo[2.2.2]octane in an amount of from 6 to 7 percent by weight, a bisquaternary compound, such as hexamethonium bromide, in an amount of from 4 to 5 percent by weight, an acid, such as citric acid, in an amount of from 2 to 3 percent by weight, and the balance water. One specific example of an ultrasonication process is as follows: LODYNE P-502, obtained from Tricon Colors as an aqueous solution containing about 15 percent by weight of the fluorocarbon, is divided into 25 gram portions. In each instance, a 25 gram portion of the LODYNE P-502 is placed in a 30 gram vial. The vial is placed into a 550 SONIC DISMEMBRATOR (obtained from Fisher Scientific Co.) tuned at 20 kiloHertz and the LODYNE P-502 is subjected to ultrasonification for a period of 10 minutes at an amplitude setting of 5, with the power turned on and off every 30 seconds. Thereafter the vial is allowed to stand overnight, after which the top layer in the vial is used to prepare ink compositions. To avoid excessive heating of the ink during the ultrasonification process, the ink can be jacked cooled during the process, and/or the ultrasonification can be pulsed instead of continuous; for example, for a process entailing application of ultrasonification for 5 minutes, the process can be pulsed at one second on and one second off alternately for a period of 10 minutes. Reduction in liposome size by ultrasonification enables advantages such as enhanced shelf life of the ink and reduced ink viscosity. Ultrasonification also results in a narrower range of liposome particle diameters. In yet another specific embodiment, neither the fluorocarbon nor the ink is subjected to ultrasonification during the formulation process. Inks suitable for ink jet printing exhibiting a liquid crystalline phase at certain temperatures are known, as disclosed in, for example, U.S. Patent 5,492,559, U.S. Patent 5,551,973, and U.S. Patent 5,643,357. Fluorocarbon materials such as LODYNE P-502, available from Ciba-Geigy, when received from the manufacturer, contain liquid crystals as observed by microscopic inspection under polarized illumination. Inks containing the fluorocarbon and other ink vehicle ingredients, such as betaine/dipropylene glycol and betaine/imidazole, retain the fluorocarbon liquid crystal structures. When two or more of these inks of different colors are incorporated into a thermal ink jet printer, such as a Hewlett-Packard DeskJet® 500C, and printed onto a substrate such as plain paper, the resulting multicolored images exhibit improved intercolor bleed repression characteristics compared to inks of identical composition but wherein the fluorocarbon was ultrasonified prior to incorporation into the ink composition and inks of identical composition which were subjected to ultrasonification subsequent to ink preparation. The inks of the present invention may be used in a process which entails incorporating an ink composition of the present invention into an ink jet printing apparatus and causing droplets of the ink composition to be ejected in an imagewise pattern onto a substrate. In a particularly preferred embodiment, the printing apparatus employs a thermal ink jet process wherein the ink in the nozzles is selectively heated in an imagewise pattern, thereby causing droplets of the ink to be ejected in imagewise pattern. Any suitable substrate can be employed, including plain papers such as Xerox® 4024 papers, ruled notebook paper, bond paper, silica coated papers such as Sharp Company silica coated paper, and JuJo paper, transparency materials, fabrics, textile products, plastics, polymeric films, and inorganic substrates such as metals and wood. In a preferred embodiment, the process entails printing onto a porous or ink absorbent substrate, such as plain paper. Specific embodiments of the invention will now be described in detail. All parts and percentages are by weight unless otherwise indicated. EXAMPLE Ia LODYNE P-502, obtained from Ciba-Geigy as an aqueous solution containing about 15 percent by weight of the fluorocarbon, was divided into 25 gram portions. In each instance, a 25 gram portion of the LODYNE P-502 was placed in a 30 gram vial. The vial was placed into a 550 SONIC DISMEMBRATOR (obtained from Fisher Scientific Co.) tuned at 20 kiloHertz and the LODYNE P-502 was subjected to ultrasonification for a period of 10 minutes at an amplitude setting of 5, with the power turned on and off every 30 seconds. Thereafter the vial was allowed to stand overnight, after which the top layer in the vial was used to prepare ink compositions. Thereafter, ink compositions were prepared by simple mixing of the following ingredients, wherein the relative amounts of dye and biocide were constant for all inks prepared and the relative amounts of LODYNE P-502, imidazole, and water were varied over the indicated ranges: Ingredient Supplier Amount (% b.w.) Acid Yellow 17 dye (solids) Tricon Colors 3 DOWICIL 150 biocide Dow Chemical Co. 0.1 LODYNE P-502 (as supplied; contains 15 percent by weight fluorocarbon solids) Ciba-Geigy 1 -- 80 imidazole Aldrich Chemical Co. 0 -- 80 deionized water - - - 0 -- 80 The ink compositions thus prepared were tested for shelf stability characteristics by observing the effects of varying amounts of LODYNE P-502 and imidazole in the ink system. A stability diagram was prepared from this information and is shown in Figure 1. In the stability diagrams, the triangle represents the relative amounts of water, LODYNE P-502, and imidazole in the ink with respect to each other (and ignoring the other ink ingredients). Each apex of the triangle represents an ink wherein the water/LODYNE P-502/imidazole system contained 100 percent by weight of the ingredient with which the triangle apex is labeled and 0 percent by weight of the other two ingredients. For example, in Figure 1, the left triangle apex represents an ink containing water, but no imidazole and no LODYNE P-502. Each side of the triangle represents ink compositions wherein the water/LODYNE P-502/imidazole system contained varying amounts of the two ingredients labeling each triangle apex with which the triangle side is connected but contained 0 percent by weight of the ingredient with which the apex opposite the triangle side is labeled. For example, in Figure 1, the bottom edge of the triangle represents inks containing water and LODYNE P-502 in varying amounts, but containing no imidazole. Ink compositions containing all three ingredients in varying amounts are represented within the boundaries of the triangle. As the stability diagram in Figure 1 indicates, the inks remained homogeneous under centrifugation at 2,400 revolutions per minute for 30 minutes in an 8-foot arm centrifuge when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 15 -- 75 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 60 deionized water 0.01 -- 65 The inks with ideal shelf stability characteristics thus contained the following ingredients in the indicated amount ranges. Ingredient Amount (% b.w.) Acid Yellow 17 dye(solids) 3 DOWICIL 150 biocide 0.1 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 2.07 -- 4.14 imidazole 10.4 -- 20.7 deionized water 68.4 -- 89.1 EXAMPLE Ib The process of Example I was repeated with the exception that the inks all contained a fixed amount of citric acid. Ingredient Supplier Amount (% b.w.) Acid Yellow 17 dye (solids) Tricon Colors 3 DOWICIL 150 biocide Dow Chemical Co. 0.1 citric acid Aldrich Chemical Co. 1 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) Ciba-Geigy 1 -- 80 imidazole Aldrich Chemical Co. 0 -- 80 deionized water - - - 0 -- 80 The ink compositions thus prepared were tested for shelf stability characteristics by observing the effects of varying amounts of LODYNE P-502 and imidazole in the ink system. The inks remained homogeneous under centrifugation at 2,400 revolutions per minute for 30 minutes in an 8-foot arm centrifuge when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 15 -- 75 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 60 deionized water 0.01 -- 65 Within these ranges, the preferred ranges for the relative amounts of these three ingredients were as follows: Ingredient Relative amount range (% b.w.) imidazole 15 -- 30 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 20 -- 40 deionized water 40 -- 60 EXAMPLE II The process of Example la was repeated with the exception that the pH of the inks prepared was adjusted in each instance to 8.75 by the addition of citric acid. Ingredient Supplier Amount (% b.w.) Acid Yellow 17 dye (solids) Tricon Colors 3 DOWICIL 150 biocide Dow Chemical Co. 0.1 citric acid Aldrich Chemical Co. 0 -- 4 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) Ciba-Geigy 1 -- 80 imidazole Aldrich Chemical Co. 0 -- 80 deionized water - - - 0 -- 80 The ink compositions thus prepared were tested for shelf stability characteristics by observing the effects of varying amounts of LODYNE P-502 and imidazole in the ink system. A stability diagram was prepared from this information and is shown in Figure 2. As the stability diagram in Figure 2 indicates, the inks remained homogeneous under centrifugation at 2,400 revolutions per minute for 30 minutes in an 8-foot arm centrifuge when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 25 -- 65 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 45 deionized water 0.01 -- 75 Within these ranges, the preferred ranges for the relative amounts of these three ingredients were as follows: Ingredient Relative amount range (% b.w.) imidazole 25 -- 30 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 25 deionized water 50 -- 75 The inks with ideal shelf stability characteristics thus contained the following ingredients in the indicated amount ranges. Ingredient Amount (% b.w.) Acid Yellow 17 dye (solids) 3 DOWICIL 150 biocide 0.1 citric acid 0.8 -- 1.1 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 0.1 -- 2.7 imidazole 17 -- 21 deionized water 62 -- 80 EXAMPLE III The process of Example la was repeated with the exceptions that the inks all contained a fixed amount of betaine and that the pH of the inks prepared was adjusted in each instance to 8.75 by the addition of citric acid. Ingredient Supplier Amount (% b.w.) Acid Yellow 17 dye (solids) Tricon Colors 3 DOWICIL 150 biocide Dow Chemical Co. 0.1 betaine FinnSugar Bioproducts 15 citric acid Aldrich Chemical Co. 0 -- 5 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) Ciba-Geigy 1 -- 80 imidazole Aldrich Chemical Co. 0 -- 80 deionized water - - - 0 -- 80 The ink compositions thus prepared were tested for shelf stability characteristics by observing the effects of varying amounts of LODYNE P-502 and imidazole in the ink system. A stability diagram was prepared from this information and is shown in Figure 3. As the stability diagram in Figure 3 indicates, the inks remained homogeneous under centrifugation at 2,400 revolutions per minute for 30 minutes in an 8-foot arm centrifuge when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 0.01 -- 80 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 35 deionized water 0.01 -- 80 Within these ranges, the preferred ranges for the relative amounts of these three ingredients were as follows: Ingredient Relative amount range (% b.w.) imidazole 2 -- 7 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 15 deionized water 65 -- 80 The inks with ideal shelf stability characteristics thus contained the following ingredients in the indicated amount ranges. Ingredient Amount (% b.w.) Acid Yellow 17 dye (solids) 3 DOWICIL 150 biocide 0.1 betaine 15 citric acid 0.06 -- 0.2 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 0.1 -- 1.3 imidazole 1 -- 4 deionized water 62 -- 71 EXAMPLE IV The process of Example Ia was repeated with the exceptions that the inks all contained a fixed amount of cyclohexylpyrrolidinone and a fixed amount of citric acid. Ingredient Supplier Amount (% b.w.) Acid Yellow 17 dye (solids) Tricon Colors 3 DOWICIL 150 biocide Dow Chemical Co. 0.1 cyclohexylpyrrolidone BASF 2 citric acid Aldrich Chemical Co. 1 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) Ciba-Geigy 1 -- 80 imidazole Aldrich Chemical Co. 0 -- 80 deionized water - - - 0 -- 80 The ink compositions thus prepared were tested for shelf stability characteristics by observing the effects of varying amounts of LODYNE P-502 and imidazole in the ink system. A stability diagram was prepared from this information and is shown in Figure 4. As the stability diagram in Figure 4 indicates, the inks remained homogeneous after shelf storage for 6 months when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 20 -- 50 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 20 deionized water 35 -- 70 Within these ranges, the preferred ranges for the relative amounts of these three ingredients were as follows: Ingredient Relative amount range (% b.w.) imidazole 20 -- 30 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 10 -- 20 deionized water 50 -- 70 The inks with ideal shelf stability characteristics thus contained the following ingredients in the indicated amount ranges. Ingredient Amount (% b.w.) Acid Yellow 17 dye (solids) 3 DOWICIL 150 biocide 0.1 cyclohexylpyrrolidone 2 citric acid 1 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 2 imidazole 13 -- 21 deionized water 60 -- 74 EXAMPLE V The process of Example la was repeated with the exceptions that the inks all contained a fixed amount of cyclohexylpyrrolidinone and that the pH of the inks prepared was adjusted in each instance to 8.75 by the addition of citric acid. Ingredient Supplier Amount (% b.w.) Acid Yellow 17 dye (solids) Tricon Colors 3 DOWICIL 150 biocide Dow Chemical Co. 0.1 cyclohexylpyrrolidone BASF 2 citric acid Aldrich Chemical Co. 0 -- 5 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) Ciba-Geigy 1 -- 80 imidazole Aldrich Chemical Co. 0 -- 80 deionized water - - - 0 -- 80 The ink compositions thus prepared were tested for shelf stability characteristics by observing the effects of varying amounts of LODYNE P-502 and imidazole in the ink system. A stability diagram was prepared from this information and is shown in Figure 5. As the stability diagram in Figure 5 indicates, the inks remained homogeneous after shelf storage for 6 months when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 25 -- 65 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 30 deionized water 15 -- 70 Within these ranges, the preferred ranges for the relative amounts of these three ingredients were as follows: Ingredient Relative amount range (% b.w.) imidazole 25 -- 35 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 10 -- 25 deionized water 50 -- 60 The inks with ideal shelf stability characteristics thus contained the following ingredients in the indicated amount ranges. Ingredient Amount (% b.w.) Acid Yellow 17 dye (solids) 3 DOWICIL 150 biocide 0.1 cyclohexylpyrrolidone 2 citric acid 0.8 -- 1.2 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1.0 -- 2.6 imidazole 17 -- 24 deionized water 61 -- 68 EXAMPLE VI The process of Example la was repeated with the exceptions that the inks all contained a fixed amount of cyclohexylpyrrolidinone and that the pH of the inks prepared was adjusted in each instance to 8.25 by the addition of citric acid. Ingredient Supplier Amount (% b.w.) Acid Yellow 17 dye (solids) Tricon Colors 3 DOWICIL 150 biocide Dow Chemical Co. 0.1 cyclohexylpyrrolidone BASF 2 citric acid Aldrich Chemical Co. 0 -- 5 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) Ciba-Geigy 1 -- 80 imidazole Aldrich Chemical Co. 0 -- 80 deionized water - - - 0 -- 80 The ink compositions thus prepared were tested for shelf stability characteristics by observing the effects of varying amounts of LODYNE P-502 and imidazole in the ink system. A stability diagram was prepared from this information and is shown in Figure 6. As the stability diagram in Figure 6 indicates, the inks remained homogeneous under centrifugation at 2,400 revolutions per minute for 30 minutes in an 8-foot arm centrifuge when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 2 -- 25 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 25 deionized water 65 -- 80 Within these ranges, the preferred ranges for the relative amounts of these three ingredients were as follows: Ingredient Relative amount range (% b.w.) imidazole 2 -- 7 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 10 -- 25 deionized water 75 -- 80 The inks with ideal shelf stability characteristics thus contained the following ingredients in the indicated amount ranges. Ingredient Amount (% b.w.) Acid Yellow 17 dye (solids) 3 DOWICIL 150 biocide 0.1 cyclohexylpyrrolidone 2 citric acid 0.07 -- 0.24 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 6.8 -- 17.0 imidazole 1.4 -- 4.8 deionized water 51 -- 55 EXAMPLE VII The process of Example la was repeated with the exceptions that the inks all contained a fixed amount of SOLSPERSE 27,000 polymer and that the pH of the inks prepared was adjusted in each instance to 8.75 by the addition of citric acid. Ingredient Supplier Amount (% b.w.) Acid Yellow 17 dye (solids) Tricon Colors 3 DOWICIL 150 biocide Dow Chemical Co. 0.1 SOLSPERSE 27,000 ICI 0.1 citric acid Aldrich Chemical Co. 0 -- 5 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) Ciba-Geigy 1 -- 80 imidazole Aldrich Chemical Co. 0 --80 deionized water - - - 0 -- 80 The ink compositions thus prepared were tested for shelf stability characteristics by observing the effects of varying amounts of LODYNE P-502 and imidazole in the ink system. A stability diagram was prepared from this information and is shown in Figure 7. As the stability diagram in Figure 7 indicates, the inks remained homogeneous after shelf storage for 6 months when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 25 -- 55 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 15 -- 35 deionized water 25 -- 55 As the stability diagram in Figure 7 indicates, the inks also remained homogeneous after shelf storage for 6 months when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 2 -- 7 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 15 deionized water 75 -- 80 The inks with ideal shelf stability characteristics thus contained the following ingredients in the indicated amount ranges. Ingredient Amount (% b.w.) Acid Yellow 17 dye (solids) 3 DOWICIL 150 biocide 0.1 SOLSPERSE 27,000 0.1 citric acid 0.07 -- 0.25 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 0.1 -- 1.6 imidazole 1.4 -- 4.9 deionized water 79 -- 83 EXAMPLE VIII The process of Example la was repeated with the exceptions that the inks all contained a fixed amount of betaine and a fixed amount of cyclohexylpyrrolidinone, and that the pH of the inks prepared was adjusted in each instance to 8.75 by the addition of citric acid. Ingredient Supplier Amount (% b.w.) Acid Yellow 17 dye (solids) Tricon Colors 3 DOWICIL 150 biocide Dow Chemical Co. 0.1 betaine FinnSugar Bioproducts 15 cyclohexylpyrrolidone BASF 2 citric acid Aldrich Chemical Co. 0 -- 5 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) Ciba-Geigy 1 -- 80 imidazole Aldrich Chemical Co. 0 -- 80 deionized water - - - 0 -- 80 The ink compositions thus prepared were tested for shelf stability characteristics by observing the effects of varying amounts of LODYNE P-502 and imidazole in the ink system. A stability diagram was prepared from this information and is shown in Figure 8. As the stability diagram in Figure 8 indicates, the inks remained homogeneous under centrifugation at 2,400 revolutions per minute for 30 minutes in an 8-foot arm centrifuge when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 0.01 -- 80 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 25 deionized water 0.01 -- 80 Within these ranges, the preferred ranges for the relative amounts of these three ingredients were as follows: Ingredient Relative amount range (% b.w.) imidazole 2 -- 7 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 10 -- 25 deionized water 65 -- 80 The inks with ideal shelf stability characteristics thus contained the following ingredients in the indicated amount ranges. Ingredient Amount (% b.w.) Acid Yellow 17 dye (solids) 3 DOWICIL 150 biocide 0.1 betaine 15 cyclohexylpyrrolidone 2 citric acid 0.05 -- 0.19 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 0.8 -- 2.0 imidazole 1 -- 3.7 deionized water 61 -- 69 EXAMPLE IX The process of Example la was repeated with the exceptions that the inks all contained a fixed amount of betaine and a fixed amount of SOLSPERSE 27,000 polymer, and that the pH of the inks prepared was adjusted in each instance to 8.75 by the addition of citric acid. Ingredient Supplier Amount (% b.w.) Acid Yellow 17 dye (solids) Tricon Colors 3 DOWICIL 150 biocide Dow Chemical Co. 0.1 betaine FinnSugar Bioproducts 15 SOLSPERSE 27,000 ICI 0.1 citric acid Aldrich Chemical Co. 0 -- 5 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) Ciba-Geigy 1 -- 80 imidazole Aldrich Chemical Co. 0 -- 80 deionized water - - - 0 -- 80 The ink compositions thus prepared were tested for shelf stability characteristics by observing the effects of varying amounts of LODYNE P-502 and imidazole in the ink system. A stability diagram was prepared from this information and is shown in Figure 9. As the stability diagram in Figure 9 indicates, the inks remained homogeneous after shelf storage for 6 months when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 2 -- 25 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 25 deionized water 65 -- 80 As the stability diagram in Figure 9 also indicates, the inks remained homogeneous after shelf storage for 6 months when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 35 -- 75 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 35 deionized water 5 -- 55 Within these ranges, the preferred ranges for the relative amounts of these three ingredients were as follows: Ingredient Relative amount range (% b.w.) imidazole 2 -- 7 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 25 deionized water 75 -- 80 The inks with ideal shelf stability characteristics thus contained the following ingredients in the indicated amount ranges. Ingredient Amount (% b.w.) Acid Yellow 17 dye (solids) 3 DOWICIL 150 biocide 0.1 betaine 15 SOLSPERSE 27,000 0.1 citric acid 0.06 -- 0.4 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 0.08 -- 2.1 imidazole 1 -- 8 deionized water 50 -- 52 EXAMPLE X The process of Example la was repeated with the exceptions that the inks all contained a fixed amount of cyclohexylpyrrolidinone and a fixed amount of SOLSPERSE 27,000 polymer, and that the pH of the inks prepared was adjusted in each instance to 8.75 by the addition of citric acid. Ingredient Supplier Amount (% b.w.) Acid Yellow 17 dye (solids) Tricon Colors 3 DOWICIL 150 biocide Dow Chemical Co. 0.1 cyclohexylpyrrolidone BASF 2 SOLSPERSE 27,000 ICI 0.1 citric acid Aldrich Chemical Co. 0 -- 5 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) Ciba-Geigy 1 -- 80 imidazole Aldrich Chemical Co. 0 -- 80 deionized water - - - 0 -- 80 The ink compositions thus prepared were tested for shelf stability characteristics by observing the effects of varying amounts of LODYNE P-502 and imidazole in the ink system. A stability diagram was prepared from this information and is shown in Figure 10. As the stability diagram in Figure 10 indicates, the inks remained homogeneous after shelf storage for 6 months when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 2 -- 25 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 25 deionized water 65 -- 80 As the stability diagram in Figure 10 indicates, the inks also remained homogeneous after shelf storage for 6 months when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 5 -- 65 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 75 deionized water 5 -- 55 As the stability diagram in Figure 10 indicates, the inks also remained homogeneous after shelf storage for 6 months when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 2 -- 12 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 75 -- 80 deionized water 5 -- 15 Within these ranges, the preferred ranges for the relative amounts of these three ingredients were as follows: Ingredient Relative amount range (% b.w.) imidazole 2 -- 7 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 25 deionized water 75 -- 80 The inks with ideal shelf stability characteristics thus contained the following ingredients in the indicated amount ranges. Ingredient Amount (% b.w.) Acid Yellow 17 dye (solids) 3 DOWICIL 150 biocide 0.1 cyclohexylpyrrolidone 2 SOLSPERSE 27,000 0.1 citric acid 0.035 -- 0.85 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 0.21 -- 0.71 imidazole 0.7 -- 17 deionized water 78 -- 81 EXAMPLE XI The process of Example la was repeated with the exceptions that the inks all contained a fixed amount of betaine, a fixed amount of cyclohexylpyrrolidinone, and a fixed amount of SOLSPERSE 27,000 polymer, and that the pH of the inks prepared was adjusted in each instance to 8.75 by the addition of citric acid. Ingredient Supplier Amount (% b.w.) Acid Yellow 17 dye (solids) Tricon Colors 3 DOWICIL 150 biocide Dow Chemical Co. 0.1 betaine FinnSugar Bioproducts 15 cyclohexylpyrrolidone BASF 2 SOLSPERSE 27,000 ICI 0.1 citric acid Aldrich Chemical Co. 0 -- 5 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) Ciba-Geigy 1 -- 80 imidazole Aldrich Chemical Co. 0 -- 80 deionized water - - - 0 -- 80 The ink compositions thus prepared were tested for shelf stability characteristics by observing the effects of varying amounts of LODYNE P-502 and imidazole in the ink system. A stability diagram was prepared from this information and is shown in Figure 11. As the stability diagram in Figure 11 indicates, the inks remained homogeneous under centrifugation at 2,400 revolutions per minute for 30 minutes in an 8-foot arm centrifuge when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 2 -- 25 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 25 deionized water 65 -- 80 As the stability diagram in Figure 11 indicates, the inks also remained homogeneous under centrifugation at 2,400 revolutions per minute for 30 minutes in an 8-foot arm centrifuge when the inks contained relative amounts of water, imidazole, and LODYNE P-502 (with respect to each other and ignoring the other ink ingredients) as follows: Ingredient Relative amount range (% b.w.) imidazole 25 -- 75 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 1 -- 55 deionized water 5 -- 65 Within these ranges, the preferred ranges for the relative amounts of these three ingredients were as follows: Ingredient Relative amount range (% b.w.) imidazole 0 -- 15 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 35 -- 55 deionized water 45 -- 55 The inks with ideal shelf stability characteristics thus contained the following ingredients in the indicated amount ranges. Ingredient Amount (% b.w.) Acid Yellow 17 dye (solids) 3 DOWICIL 150 biocide 0.1 betaine 15 cyclohexylpyrrolidone 2 SOLSPERSE 27,000 0.1 citric acid 0.035 -- 0.85 LODYNE P-502 (as supplied; contains 15% b.w. fluorocarbon solids) 0.21 -- 0.71 imidazole 0.7 -- 17 deionized water 78 -- 81 EXAMPLE XII An ink composition was prepared as follows. Deionized water (94.75 grams) and imidazole (obtained from Aldrich Chemical Co., Milwaukee, WI, 20 grams) were admixed to form a mixture having a pH of 10.18 at 23.7°C. The pH of the mixture was then adjusted by the addition of phosphorous acid (obtained from Rhone-Poulenc, Cranbury, NJ, 0.8074 gram), thereby bringing the pH of the mixture to 8.75 at 25.0°C. To the mixture were then added betaine (obtained from Finnsugar Bioproducts, Helsinki, Finland, 30 grams), DOWICIL 150/200 biocide (obtained from Dow Chemical Co., Midland, Ml, 0.2 gram), SURFYNOL GA surfactant (obtained from Air Products and Chemicals Co., Allentown, PA, 0.8 gram), PROJET FAST YELLOW 2 dye (obtained from Zeneca Colours, Dighton, MA, solids only (solvent removed), 6 grams), LODYNE P-502 (14.2 percent by weight solids, obtained from Ciba-Geigy, Ardsley, NY, 42.26 grams, first subjected to ultrasonification by the process described in Example la), and additional deionized water (5.18 grams). The mixture was then roll milled for 30 minutes, followed by filtration through a 1.2 micron 47 millimeter Versapore-1200 filter at 2 pounds per square inch over a period of 10 minutes and 12 seconds. The ink composition thus prepared exhibited a viscosity of 3.96 centipoise at 25°C, a surface tension of 22.9 dynes per centimeter, a pH of 8.77 at 23.5°C, and a conductivity of 7.10 millimhos. After 6 months of shelf storage, the ink exhibited a viscosity of 4.01 centipoise. EXAMPLE XIII An ink composition was prepared as follows. Deionized water (23.68 grams) and imidazole (obtained from Aldrich Chemical Co., Milwaukee, WI, 5 grams) were admixed to form a mixture having a pH of 10.95 at 18.7°C. The pH of the mixture was then adjusted by the addition of 2-keto glutaric acid (obtained from Aldrich Chemical Co., Milwaukee, WI, 0.2504 gram), thereby bringing the pH of the mixture to 8.75 at 20.4°C. To the mixture were then added sarcosine (obtained from Aldrich Chemical Co., Milwaukee, WI, 7.5 grams), DOWICIL 150/200 biocide (obtained from Dow Chemical Co., Midland, Ml, 0.05 gram), SURFYNOL GA surfactant (obtained from Air Products and Chemicals Co., Allentown, PA, 0.208 gram), PROJET FAST YELLOW 2 dye (obtained from Zeneca Colours, Dighton, MA, solids only (solvent removed), 1.5 grams), LODYNE P-502 (14.2 percent by weight solids, obtained from Ciba-Geigy, Ardsley, NY, 10.56 grams, first subjected to ultrasonification by the process described in Example la), and additional deionized water (1.25 grams). The mixture was then roll milled for 30 minutes, followed by filtration through a 1.2 micron 47 millimeter Versapore-1200 filter at 2 pounds per square inch over a period of 3 minutes and 22 seconds. The ink composition thus prepared exhibited a viscosity of 4.84 centipoise at 25°C, a surface tension of 25.2 dynes per centimeter, a pH of 8.56 at 24.5°C, and a conductivity of 8.56 millimhos. EXAMPLE XIV An ink composition was prepared by simple mixing of the following ingredients: Ingredient Supplier Amount deionized water - - - 17.56 grams imidazole Aldrich Chemical Co. 6.01 grams citric acid Aldrich Chemical Co. 0.3 gram betaine Finnsugar Bioproducts 9.01 grams DOWICIL 150 biocide Dow Chemical Co. 0.06 gram Acid Red 52 dye (10% by weight dye solids) Tricon Colors 15.03 grams LODYNE P-502 Ciba-Geigy 12.1 grams The mixture was filtered through a 1.2 micron VERSAPORE-1200 filter at 10 pounds per square inch over a period of 30 seconds. The resulting ink exhibited a viscosity of 2.25 centipoise at 25°C. After maintaining the ink for 5 days at 50°C, the ink exhibited a viscosity of 2.21 centipoise at 25°C. The ink exhibited a conductivity of 8.84 millimhos per square centimeter, a surface tension of 28.6 dynes per centimeter, and a pH of 8.78 at 24.8°C. The ink remained monophase after centrifugation for 30 minutes at 2,700 revolutions per minute. The ink remained monophase after being undisturbed for 5 days. When the ink was coated onto Courtland 4024 DP Image Series Elite paper (felt side) with a #3 wire-wound rod, the resulting image dried in 3 seconds. EXAMPLE XV An ink composition was prepared by simple mixing of the following ingredients: Ingredient Supplier Amount deionized water - - - 8.19 grams imidazole Aldrich Chemical Co. 3.01 grams citric acid Aldrich Chemical Co. 0.15 gram betaine Finnsugar Bioproducts 4.5 grams cyclohexylpyrrolidone BASF 0.61 gram DOWICIL 150 biocide Dow Chemical Co. 0.03 gram Acid Red 52 dye (10% by weight dye solids) Tricon Colors 7.51 grams LODYNE P-502 Ciba-Geigy 6.05 grams The resulting ink exhibited a viscosity of 3.21 centipoise at 25°C. After maintaining the ink for 5 days at 50°C, the ink exhibited a viscosity of 3.11 centipoise at 25°C. The ink exhibited a conductivity of 3.75 millimhos per square centimeter, a surface tension of 26.3 dynes per centimeter, and a pH of 8.67 at 22.8°C. The ink remained monophase after centrifugation for 30 minutes at 2,700 revolutions per minute. The ink remained monophase after being undisturbed for 5 days. When the ink was coated onto Courtland 4024 DP Image Series Elite paper (felt side) with a #3 wire-wound rod, the resulting image dried in 0.5 second. EXAMPLE XVI An ink composition was prepared by simple mixing of the following ingredients: Ingredient Supplier Amount deionized water - - - 8.19 grams imidazole Aldrich Chemical Co. 3 grams citric acid Aldrich Chemical Co. 0.15 gram betaine Finnsugar Bioproducts 4.5 grams butyl carbitol Van Waters & R 0.6 gram DOWICIL 150 biocide Dow Chemical Co. 0.03 gram Acid Red 52 dye (10% by weight dye solids) Tricon Colors 7.5 grams LODYNE P-502 Ciba-Geigy 6.03 grams The resulting ink exhibited a viscosity of 2.86 centipoise at 25°C. After maintaining the ink for 5 days at 50°C, the ink exhibited a viscosity of 2.81 centipoise at 25°C. The ink exhibited a conductivity of 4.02 millimhos per square centimeter, a surface tension of 25.6 dynes per centimeter, and a pH of 8.51 at 22.6°C. The ink remained monophase after centrifugation for 30 minutes at 2,700 revolutions per minute. The ink remained monophase after being undisturbed for 5 days. When the ink was coated onto Courtland 4024 DP Image Series Elite paper (felt side) with a #3 wire-wound rod, the resulting image dried in 0.5 second. EXAMPLE XVII An ink composition was prepared by simple mixing of the following ingredients: Ingredient Supplier Amount deionized water - - - 7.3 grams imidazole Aldrich Chemical Co. 3 grams citric acid Aldrich Chemical Co. 0.15 gram betaine Finnsugar Bioproducts 4.5 grams tripropylene glycol monomethyl ether Dow Chemical Co. 1.5 gram DOWICIL 150 biocide Dow Chemical Co. 0.03 gram Acid Red 52 dye (10% by weight dye solids) Tricon Colors 7.5 grams LODYNE P-502 Ciba-Geigy 6.03 grams The resulting ink exhibited a viscosity of 3.86 centipoise at 25°C. After maintaining the ink for 5 days at 50°C, the ink exhibited a viscosity of 3.86 centipoise at 25°C. The ink exhibited a conductivity of 2.81 millimhos per square centimeter, a surface tension of 24.1 dynes per centimeter, and a pH of 8.58 at 23.3°C. The ink remained monophase after centrifugation for 30 minutes at 2,700 revolutions per minute. The ink remained monophase after being undisturbed for 5 days. When the ink was coated onto Courtland 4024 DP Image Series Elite paper (felt side) with a #3 wire-wound rod, the resulting image dried in 0.5 second. EXAMPLE XVIII An ink composition was prepared by simple mixing of the following ingredients: Ingredient Supplier Amount deionized water - - - 8.68 grams imidazole Aldrich Chemical Co. 3 grams citric acid Aldrich Chemical Co. 0.15 gram betaine Finnsugar Bioproducts 4.5 grams SURFYNOL GA Air Products & Chemicals Co. 0.12 gram DOWICIL 150 biocide Dow Chemical Co. 0.03 gram Acid Red 52 dye (10% by weight dye solids) Tricon Colors 7.5 grams LODYNE P-502 Ciba-Geigy 6.03 grams The resulting ink exhibited a viscosity of 6.71 centipoise at 25°C. After maintaining the ink for 5 days at 50°C, the ink exhibited a viscosity of 4.81 centipoise at 25°C. The ink exhibited a conductivity of 3.42 millimhos per square centimeter, a surface tension of 26.0 dynes per centimeter, and a pH of 8.62 at 21.9°C. The ink remained monophase after centrifugation for 30 minutes at 2,700 revolutions per minute. The ink remained monophase after being undisturbed for 5 days. EXAMPLE XIX 200 Grams of LODYNE P-502, obtained from Ciba-Geigy as an aqueous solution containing about 15 percent by weight of the fluorocarbon, was ultrasonicated by incorporating the material into a 550 SONIC DISMEMBRATOR (obtained from Fisher Scientific Co.) and subjecting the material to ultrasonication for 2 hours. Thereafter, the LODYNE P-502 exhibited a viscosity of 3.14 centipoise. Upon standing undisturbed for several weeks, only a slight silt was observed in the sonicate. It is believed that ink compositions prepared from the ultrasonicated fluorocarbon material will exhibit improved shelf stability and lowered viscosity compared to ink compositions prepared from fluorocarbon material ultrasonicated at lower temperatures. EXAMPLE XX An ink composition was prepared by simple mixing of the following ingredients: Ingredient Supplier Amount deionized water - - - 31.08 grams 1,4-diazabicyclo[2.2.2]octane Aldrich Chemical Co. 0.6 grams citric acid Aldrich Chemical Co. 0.36 gram betaine Finnsugar Bioproducts 9 grams hexamethonium bromide hydrate Aldrich Chemical Co. 1.5 grams cyclohexylpyrrolidone BASF 1.5 grams DOWICIL 150 biocide Dow Chemical Co. 0.06 gram Acid Red Yellow 23 dye (solid) Hoechst 2.4 grams LODYNE P-502L Ciba-Geigy 13.2 grams roll mill 30 minutes The mixture was filtered through a 1.2 micron VERSAPORE-1200 filter at 2 pounds per square inch over a period of 10 seconds. The resulting ink exhibited a viscosity of 3.87 centipoise at 25°C, a conductivity of 13.8 millimhos per square centimeter, a surface tension of 20.2 dynes per centimeter, and a pH of 8.88 at 25°C. The ink remained monophase after centrifugation for 30 minutes at 1.000 G forces. EXAMPLE XXI An ink composition was prepared by simple mixing of the following ingredients: Ingredient Supplier Amount deionized water - - - 9.48 grams 1,4-diazabicyclo[2.2.2]octane Aldrich Chemical Co. 0.6 grams citric acid Aldrich Chemical Co. 0.36 gram betaine Finnsugar Bioproducts 9 grams hexamethonium bromide hydrate Aldrich Chemical Co. 1.5 grams cyclohexylpyrrolidone BASF 1.8 grams DOWICIL 150 biocide Dow Chemical Co. 0.06 gram PROJET CYAN 1 dye (10 wt.% solids) Zeneca Colors 24 grams LODYNE P-502L Ciba-Geigy 13.2 grams roll mill 30 minutes The mixture was filtered through a 1.2 micron VERSAPORE-1200 filter at 2 pounds per square inch over a period of 55 seconds. The resulting ink exhibited a viscosity of 4.46 centipoise at 25°C, a conductivity of 10.8 millimhos per square centimeter, a surface tension of 19 dynes per centimeter, and a pH of 8.92 at 25°C. The ink remained monophase after centrifugation for 30 minutes at 1.000 G forces. EXAMPLE XXII An ink composition was prepared by admixing the following ingredients: Ingredient Supplier Amount (grams) deionized water - - - 31.8 Acid Yellow 17 dye solution Tricon Colors 30 betaine FinnSugar Bioproducts 15 cyclohexylpyrrolidone BASF 3 SOLSPERSE 27,000 ICI 0.1 DOWICIL 150/200 Dow Chemical Co. 0.1 LODYNE P-502 Ciba-Geigy 20 roll mill 30 minutes The resulting ink was then filtered through a 1.2 micron 47 millimeter Magna nylon filter at 2 pounds per square inch over a period of 7 seconds. The ink composition thus prepared exhibited a viscosity of 2.14 centipoise at 25°C, a pH of 7.73 at 25°C, a surface tension of 19.0 dynes per centimeter, and a conductivity of 5.15 millimhos. The ink composition thus prepared was then incorporated into a Hewlett-Packard 694C thermal ink jet printer and printed onto Xerox® 4024 DP paper and Xerox® Image Series Elite paper. Black images were also printed on the paper with the standard HP694 carbon black containing ink. The prints thus formed exhibited low intercolor bleed with a MFLEN value of 15. COMPARATIVE EXAMPLE A An ink composition was prepared by admixing the following ingredients: Ingredient Supplier Amount (grams) deionized water - - - 41.8 Acid Yellow 17 dye solution Tricon Colors 30 betaine FinnSugar Bioproducts 15 cyclohexylpyrrolidone BASF 3 SOLSPERSE 27,000 ICI 0.1 DOWICIL 150/200 Dow Chemical Co. 0.1 heptadecafluorononanoic acid ammonium salt Aldrich Chemical Co. 10 roll mill 30 minutes The resulting ink was then filtered through a 1.2 micron 47 millimeter Magna nylon filter at 2 pounds per square inch over a period of 3 minutes. The ink composition thus prepared exhibited a viscosity of 2.09 centipoise at 25°C, a pH of 10.2 at 25°C, a surface tension of 21.6 dynes per centimeter, and a conductivity of 9 millimhos. The ink composition thus prepared was then incorporated into a Hewlett-Packard 694C thermal ink jet printer and printed onto Xerox® 4024 DP paper and Xerox® Image Series Elite paper. Black images were also printed on the paper with the standard HP694 carbon black containing ink. The prints thus formed exhibited high intercolor bleed with a MFLEN value of 45. COMPARATIVE EXAMPLE B An ink composition was prepared by admixing the following ingredients: The resulting ink was then filtered through a 1.2 micron 47 millimeter Magna nylon filter at 2 pounds per square inch over a period of 20 seconds. The ink composition thus prepared exhibited a viscosity of 2.07 centipoise at 25°C, a pH of 8.4 at 25°C, a surface tension of 18.3 dynes per centimeter, and a conductivity of 29.8 millimhos. The ink composition thus prepared was then incorporated into a Hewlett-Packard 694C thermal ink jet printer and printed onto Xerox® 4024 DP paper and Xerox® Image Series Elite paper. Black images were also printed on the paper with the standard HP694 carbon black containing ink. The prints thus formed exhibited high intercolor bleed with a MFLEN value of 30.

Claims: An ink composition which comprises (a) a colorant, and (b) a liquid vehicle which comprises (i) water, and (ii) a fluorinated material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ], wherein X is a cation and n is an integer of from 3 to 20. The ink composition according to claim 1 wherein n is 5. The ink composition according to claim 1 wherein the material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ] is present in an amount of from 0.1 to 10 percent by weight of the ink. The ink composition according to claim 1 further containing a material of the formula [(F 2n+1 C n CH 2 S) 2 (CH 3 )C-CH 2 CH 2 COO - ][B + ], wherein n is an integer of from 8 to 20 and B is a cation. The ink composition according to claim 1 further containing a penetrant selected from betaine, cyclohexyl pyrrolidinone, butyl carbitol (diethylene glycol monobutyl ether), tripropylene glycol monomethyl ether, or mixtures thereof. The ink composition according to claim 5 wherein the penetrant is present in an amount of from 0.1 to 20 percent by weight of the ink. The ink composition according to claim 1 wherein the ink composition contains liquid crystals. A process for preparing an ink composition which comprises (i) subjecting a composition comprising a material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ], wherein X is a cation and n is an integer of from 3 to 20 to ultrasonification; and (ii) admixing colorant with the composition, thereby forming an ink, said ink composition further containing water. The process according to claim 8 wherein water is admixed with the material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ] in step (i). The process according to claim 8 wherein water is admixed with the material of the formula [(F 3 C(F 2 C) n CH=CHCH 2 OCH(OH)CH 2 ) 2 NCH 2 COO - ][X + ] and the colorant in step (ii).

Inventors: AVOLIO DANIELLE, BRODSKY KATHY-JO, COLT RICHARD L, GUNDLACH KURT B, HANZLIK CHERYL A, MCGRATH RACHAEL L, MONTES AILEEN M, SANCHEZ LUIS A, AVOLIO, DANIELLE, BRODSKY, KATHY-JO, COLT, RICHARD L., GUNDLACH, KURT B., HANZLIK, CHERYL A., MCGRATH, RACHAEL L., MONTES, AILEEN M., SANCHEZ, LUIS A.
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1998
Main classification: C09D11
IPC codes: B41J2, C09D11, B41M5