Ink jet inks containing oxazolidinones

Abstract: Disclosed is an ink composition which comprises water, a colorant, and a monomeric oxazolidinone compound. In one embodiment, the oxazolidinone compound is of the formula wherein R 1 is a hydrogen atom, an alkyl group, or a substituted alkyl group, and R 2 , R 3 , R 4 , and R 5 each, independently of the others, are hydrogen atoms, alkyl groups, substituted alkyl groups, or alkoxy groups. Also disclosed are ink jet printing processes using the aforementioned ink.

Description: The present invention is directed to aqueous ink compositions. More specifically, the present invention is directed to ink compositions suitable for use in ink jet printing processes. One embodiment of the present invention is directed to an ink composition which comprises water, a colorant, and a monomeric oxazolidinone compound. JP-A-6-228476 discloses a recording ink suitable for use in thermal ink jet recording comprising 3 to 20 percent by weight of 2-oxazolidinone and 3 to 12 percent by weight of a pigment. The solvent for the recording ink comprises water and a water-soluble organic solvent. The recording ink may contain further additives such as a humectant. Organic solvents and humectants included in ink jet ink compositions have a number of requirements, including water miscibility, thermal stability, hydrolytic stability, low volatility, high boiling point, high surface tension, low viscosity, compatibility with colorants, and the like. Glycols and glycol derivatives are the most widely used solvents and humectants; these materials, however, tend to result in formation of ink compositions with undesirably high viscosities, resulting in less than optimum frequency response and latency when the inks are used in ink jet printing processes. Latency in particular becomes a more critical issue with the introduction of printheads having small channels and relatively high values of dots per inch. Accordingly, while known compositions and processes are suitable for their intended purposes, a need remains for improved ink compositions suitable for use in ink jet printing processes. In addition, a need remains for ink compositions suitable for ink jet printing containing solvents or humectants with high water miscibilities. Further, a need remains for ink compositions suitable for ink jet printing containing solvents or humectants with high thermal stabilities. Additionally, a need remains for ink compositions suitable for ink jet printing containing solvents or humectants with high hydrolytic stabilities. There is also a need for ink compositions suitable for ink jet printing containing solvents or humectants with low volatilities. In addition, there is a need for ink compositions suitable for ink jet printing containing solvents or humectants with high boiling points. Further, there is a need for ink compositions suitable for ink jet printing containing solvents or humectants that are highly compatible with a large number of colorants, cosolvents, and ink additives. Additionally, there is a need for ink compositions suitable for ink jet printing containing solvents or humectants with low viscosities. A need also remains for ink compositions suitable for ink jet printing containing solvents or humectants with high surface tensions. There is also a need for ink compositions suitable for ink jet printing which have low viscosities. In addition, there is a need for ink compositions suitable for ink jet printing which exhibit improved latency characteristics. Further, a need remains for ink compositions suitable for ink jet printing which exhibit improved frequency response characteristics. Additionally, a need remains for ink compositions suitable for ink jet printing processes employing printheads with small channels and capable of printing 600 or more dots per inch. There is also a need for ink compositions suitable for ink jet printing processes which are toxicologically and environmentally safe. Further, there is a need for ink compositions suitable for ink jet printing which generate high quality images on paper. Additionally, there is a need for ink compositions suitable for ink jet printing which generate high quality images on transparencies. It is an object of the present invention to provide ink compositions and printing processes with the above noted advantages. The present invention provides an ink composition which comprises water, a colorant and a monomeric oxazolidinone compound (a) of the formula wherein R 1 is an alkyl group or a substituted alkyl group, and R 2 , R 3 , R 4 and R 5 each, independently of the others, are hydrogen atoms, alkyl groups, substituted alkyl groups or alkoxy groups; or (b) selected from the group consisting of 4-methyl-2-oxazolidinone, 5-methyl-2-oxazolidinone, 4-ethyl-2-oxazolidinone, 5-ethyl-2-oxazolidinone, 4,4-dimethyl-2-oxazolidinone, 5-ethyl-4-methyl-2-oxazolidinone and 4,4-diethyl-2-oxazolidinone. The present invention further provides a printing process which comprises the step of incorporating into an ink jet printing apparatus the ink composition as defined above. Preferred embodiments of the present invention are set forth in the sub-claims. The oxazolidinone compounds suitable for the ink compositions of the present invention are monomeric. Typical oxazolidinone compounds include those of the general formula The alkyl group (including cyclic alkyl groups) represented by R 1 preferably contains from 1 to 12 carbon atoms and more preferably from 1 to 3 carbon atoms, and may be methyl, ethyl, propyl, butyl or cyclohexyl, a substituted alkyl group, preferably with from 1 to 12 carbon atoms and more preferably with from 1 to 3 carbon atoms, wherein the substituent or substituents on the alkyl group can be hydroxy groups or alkoxy groups, including those of the general formula -(O(CH 2 ) y ) z OH, wherein y is an integer of from 1 to 4 and z is an integer of from 1 to 50, preferably from 1 to 20, more preferably from 1 to 3, and R 2 , R 3 , R 4 , and R 5 each, independently of the others, are hydrogen atoms, alkyl groups (including cyclic alkyl groups), preferably with from 1 to 12 carbon atoms and more preferably with from 1 to 3 carbon atoms, such as methyl, ethyl, propyl, butyl or cyclohexyl, substituted alkyl groups, preferably with from 1 to 12 carbon atoms and more preferably with from 1 to 3 carbon atoms, or alkoxy groups, including those of the general formula -(O(CH 2 ) y ) z OH, wherein y is an integer of from 1 to 4 and z is an integer of from 1 to 50, preferably from 1 to 20, more preferably from 1 to 3, wherein the substituent or substituents on the alkyl groups can be hydroxy groups or alkoxy groups, including those of the general formula -(O(CH 2 ) y ) z OH, wherein y is an integer of from 1 to 4 and z is an integer of from 1 to 50, preferably from 1 to 20, more preferably from 1 to 3. Materials suitable for the present invention are either liquids or solids at room temperature (about 25°C). Several of these materials also exhibit high boiling points of at least 260°C under ambient pressures, and in many cases have boiling points of over 300°C at ambient pressures. Oxazolidinone compounds (also referred to as oxazolidone compounds) can be obtained commercially, from, for example, Aldrich Chemical Co., Milwaukee, WI. Oxazolidinone compounds are also relatively easy to prepare. For example, β-amino alcohols can be treated with ethylene carbonate followed by distillation of the product to yield the desired oxazolidinone, as follows: Alternatively, the cyclic ethylene carbonate can be replaced with diethyl ketone and performed with base catalysis. The reactants are present in approximately equimolar amounts and the reaction takes about 12 hours at 45°C in a solvent such as methanol. Oxazolidinone compounds can also be prepared by the reaction of a β-amino alcohol and phosgene, as follows: The phosgene can be supplied as a gas, in solution, or as a complex with pyridine. Oxazolidinone compounds can further be prepared by the reaction of an epoxide and an isocyanate or an isothiocyanate, as follows: The reaction takes place at elevated temperatures, optionally in the presence of a solvent such as dimethylformamide, acetonitrile, dioxane or benzene, and is optionally catalyzed by materials such as secondary and tertiary amines, quaternary ammonium halides, carboxylate anions, zinc chloride, iron chloride, lithium chloride or other halide anion sources. Further information regarding the synthesis of oxazolidinone or oxazolidone compounds is disclosed in, for example, E. Dyer and H. Scott, "Preparation of Polymeric and Cyclic Urethanes and Urea From Ethylene Carbonate and Amines," J. Am. Chem. Soc., 79 , 672 (1957); V. A. Pankratov, Ts. M. Frenkel, and A. M. Fainleib, "2-Oxazolidinones," Russian Chemical Reviews, 52 (6), 576 (1983) (translated from Uspekhi Khimii, 52 , 1018 (1983)); M. E. Dyen and D. Swern, "2-Oxazolidones," Chem. Rev., 67 , 197 (1967); U.S. Patent 2,975,187; U.S. Patent 3,131,197; U.S. Patent 3,120,510; U.S. Patent 2,399,118; U.S. Patent 2,437,388; U.S. Patent 2,437,389; U.S. Patent 2,437,390; U.S. Patent 2,695,300; U.S. Patent 3,133,932; U.S. Patent 2,973,366; U.S. Patent 2,485,855; U.S. Patent 2,740,792; U.S. Patent 2,843,585; U.S. Patent 2,857,392; U.S. Patent 2,773,067; U.S. Patent 3,062,826; U.S. Patent 2,865,926; U.S. Patent 3,214,435; U.S. Patent 3,231,578; U.S. Patent 2,977,369; U.S. Patent 3,817,938; U.S. Patent 3,687,897; and U.S. Patent 2,868,801. Specific examples of suitable oxazolidinones include 3-methyl-2-oxazolidinone, of the formula 3-ethyl-2-oxazolidinone, of the formula 3-butyl-2-oxazolidinone, of the formula 3-cyclohexyl-2-oxazolidinone, of the formula 3-(hydroxyethyl)-2-oxazolidinone, of the formula 4-methyl-2-oxazolidinone, of the formula 5-methyl-2-oxazolidinone, of the formula 3,5-dimethyl-2-oxazolidinone, of the formula 3-ethyl-5-methyl-2-oxazolidinone, of the formula 3-butyl-5-methyl-2-oxazolidinone, of the formula 3-(2-hydroxypropyl)-5-methyl-2-oxazolidinone, of the formula 4-ethyl-2-oxazolidinone, of the formula 5-ethyl-2-oxazolidinone, of the formula 4,4-dimethyl-2-oxazolidinone, of the formula 5,5,3-trimethyl-2-oxazolidinone, of the formula 5-methyl-3-ethyl-2-oxazolidinone, of the formula 3-(2-hydroxypropyl)-5-methyl-2-oxazolidinone, of the formula 5-isopropyl-3-methyl-2-oxazolidinone, of the formula 5-ethyl-4-methyl-2-oxazolidinone, of the formula 5-methyl-3-(hydroxyethyl)-2-oxazolidinone, of the formula 4,5-dimethyl-3-(hydroxyethyl)-2-oxazolidinone, of the formula 5,5-dimethyl-3-ethyl-2-oxazolidinone, of the formula 3,5-diethyl-5-methyl-2-oxazolidinone, of the formula 5-methyl-3-cyclohexyl-2-oxazolidinone, of the formula 4,5-dimethyl-3-cyclohexyl-2-oxazolidinone, of the formula 3,4,5-trimethyl-2-oxazolidinone, of the formula 3-butyl-4-ethyl-5-methyl-2-oxazolidinone, of the formula 4,4-diethyl-2-oxazolidinone, of the formula 5,5-diethyl-3-methyl-2-oxazolidinone, of the formula 3-(hydroxyethoxyethyl)-2-oxazolidinone, of the formula as well as mixtures thereof. Specific oxazolidinones, including the butyl oxazolidinones, may be preferred in some instances as superior penetrants. Specific oxazolidinones, including 4-ethyl-2-oxazolidinone and 5-ethyl-2-oxazolidinone, may also be preferred for inks wherein improved edge sharpness, greater hydrogen bonding, and specific solubility, viscosity, fluidity, and surface tension characteristics are desired. Oxazolidinones wherein the ring nitrogen atom is bonded to a hydrogen atom rather than to an alkyl group may be preferred in some instances for their ability to impart to the ink higher surface tension and greater paper compatibility. Specific oxazolidinones, including 3-methyl-2-oxazolidinone, may also be preferred for their ability to impart to the ink enhanced latency properties. The oxazolidinone compound can be the sole solvent or humectant in the ink in addition to water. Alternatively, the oxazolidinone can be admixed with other solvents or humectants to form, along with water, the liquid vehicle of the ink. Examples of other suitable solvents and humectants include ethylene glycol, propylene glycol, diethylene glycols, glycerine, dipropylene glycols, polyethylene glycols, polypropylene glycols, 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, and other water miscible materials, as well as mixtures thereof. The oxazolidinone solvent or humectant is present in the ink compositions of the present invention in any effective amount. When one or more oxazolidinone compounds are the only solvent or humectant employed in the ink, typically, the oxazolidinone is present in an amount of from 0.5 to 80 percent by weight of the ink composition, and preferably from 5 to 30 percent by weight of the ink composition, although the amount can be outside these ranges. When mixtures of an oxazolidinone and another compound form the solvent or humectant system of the ink, the total amount of humectant in the ink typically is from 1 to 80 percent by weight of the ink, and preferably from 2 to 50 percent by weight of the ink, although the amount can be outside these ranges, and the total amount of oxazolidinone in the ink typically is from 0.5 to 75 percent by weight of the ink, and preferably from 5 to 30 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. Any suitable dye or mixture of dyes compatible with the ink li uid vehicle can be used, including acid dyes, basic dyes, direct dyes and reactive dyes, with water soluble anionic dyes and cationic dyes being preferred. The dye is present in the ink composition in any effective amount, typically from 0.5 to 15 percent by weight, and preferably from 1 to 10 percent by weight, 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 µm (microns), and more preferably from 0.1 to 1 µm (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 the ink in an amount of from 0.1 to 8 percent by weight, and preferably from 2 to 7 percent by weight, although the amount can be outside these ranges. 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 5 mPa·s (centipoise), and preferably is from 1 to 2.5 mPa·s (centipoise), although the viscosity can be outside this range. Ink compositions suitable for ink jet printing can be prepared by any suitable process. Typically, the inks are prepared by simple mixing of the ingredients. One process entails mixing all of the ink ingredients together and filtering the mixture to obtain an ink. Inks can be prepared by preparing a conventional ink composition according to any desired process, such as by mixing the ingredients, heating if desired, and filtering, followed by adding any desired additional additives to the mixture and mixing at room temperature with moderate shaking until a homogeneous mixture is obtained, typically from 5 to 10 minutes. Alternatively, the optional ink additives can be mixed with the other ink ingredients during the ink preparation process, which takes place according to any desired procedure, such as by mixing all the ingredients, heating if desired, and filtering. The present invention is also directed to 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 I Ink compositions containing 3-methyl-2-oxazolidinone (obtained from Aldrich Chemical Co., Milwaukee, WI), BASF X-34 black dye solution (containing 34 percent by weight of the dye compound; obtained from BASF Corp., Rensselaer, NY), water, and other additives indicated in the table below were prepared by mixing weighed amounts of the ink components into water, stirring until all of the components had dissolved (5 minutes at most), and filtering the resulting ink composition through a 1 µm (micron) filter. Ink Amt. dye (wt. %) Amt. oxazolidinone (wt. %) Other ingredients and amounts (wt. %) A 17.5 30 imidazolium chloride (2%) (buffer) (Aldrich) B 30 30 --- C 30 30 butyl carbitol (5%) (penetrant) (Aldrich) D 17 30 betaine (3%) (Aldrich) The inks were then incorporated into a thermal ink jet printing test fixture having a printhead capable of generating images at 600 dots per inch at a frequency of 3,000 kiloHertz and jetted onto Xerox® Image Series Smooth paper. Ink A exhibited a latency of greater than 75 seconds and exhibited no front face wetting after more than 10 6 drop ejections. Ink B exhibited a high surface tension of 0.45 to 0.50 mN (45 to 50 dynes) per centimeter. The ink was sufficiently fluid for jetting and exhibited a dry time of about 20 seconds. Very high concentrations of dye were enabled by this formulation. Ink C was highly fluid and fast drying, exhibiting a dry time of less than 1 second. The images generated with this ink exhibited good edge sharpness. Very high concentrations of dye were enabled by this formulation. Ink D exhibited a drying time of about 25 seconds, exhibited low jitter, and exhibited highly efficient drop generation. In general, the formulations demonstrated that the oxazolidinone compound enabled high concentrations of dye in the ink. The inks all also exhibited good latency characteristics. The formulations demonstrate that characteristics such as drying time and surface tension can be refined by the presence of additional additives, and that the oxazolidinone compound is compatible with these additives. EXAMPLE II Ink compositions containing 3-methyl-2-oxazolidinone (obtained from Aldrich Chemical Co., Milwaukee, WI), BASF X-34 black dye solution (containing 34 percent by weight of the dye compound; obtained from BASF Corp., Rensselaer, NY), water, and other additives indicated in the table below were prepared by mixing weighed amounts of the ink components into water, stirring until all of the components had dissolved (5 minutes at most), and filtering the resulting ink composition through a 1 µm (micron) filter. Ink Amt. dye (wt. %) Amt. oxazolidinone (wt. %) Other ingredients and amounts (wt. %) E 40 15 butyl carbitol (5%) (Aldrich) F 40 15 butyl carbitol (5%) (Aldrich) cyclohexyl pyrrolidinone (2%) (Aldrich) G 30 15 pentanediol (5%) (Aldrich) imidazolium chloride (10%) (Aldrich) H 30 15 hexanediol (2%) (Aldrich) cyclohexyl pyrrolidinone (1%) (Aldrich) imidazolium chloride (10%) (Aldrich) I 30 15 butyl carbitol (5%) (Aldrich) imidazolium chloride (10%) (Aldrich) All of the inks thus prepared exhibited complete compatibility of the ink ingredients subsequent to mixing. The inks were then incorporated into a thermal ink jet printing test fixture having a printhead capable of generating images at 600 dots per inch at a frequency of 3,000 kiloHertz and jetted onto Xerox@ Image Series Smooth paper. All of the inks were fast drying, with dry times of from 1 to 4 seconds.

Claims: An ink composition which comprises water, a colorant and a monomeric oxazolidinone compound (a) of the formula wherein R 1 is an alkyl group or a substituted alkyl group, and R 2 , R 3 , R 4 , and R 5 each, independently of the others, are hydrogen atoms, alkyl groups, substituted alkyl groups or alkoxy groups; or (b) selected from the group consisting of 4-methyl-2-oxazolidinone, 5-methyl-2-oxazolidinone, 4-ethyl-2-oxazolidinone, 5-ethyl-2-oxazolidinone, 4,4-dimethyl-2-oxazolidinone, 5-ethyl-4-methyl-2-oxazolidinone and 4,4-diethyl-2-oxazolidinone. The ink composition of claim 1 wherein the oxazolidinone compound is 3-methyl-2-oxazolidinone, 3-ethyl-2-oxazolidinone, 3-butyl-2-oxazolidinone, 3-cyclohexyl-2-oxazolidinone, 3-(hydroxyethyl)-2-oxazolidinone, 3,5-dimethyl-2-oxazolidinone, 3-ethyl-5-methyl-2-oxazolidinone, 3-butyl-5-methyl-2-oxazolidinone, 3-(2-hydroxypropyl)-5-methyl-2-oxazolidinone, 5,5,3-trimethyl-2-oxazolidinone, 5-methyl-3-ethyl-2-oxazolidinone, 3-(2-hydroxypropyl)-5-methyl-2-oxazolidinone, 5-isopropyl-3-methyl-2-oxazolidinone, 5-methyl-3-(hydroxyethyl)-2-oxazolidinone, 4,5-dimethyl-3-(hydroxyethyl)-2-oxazolidinone, 5,5-dimethyl-3.ethyl-2-oxazolidinone, 3,5-diethyl-5-methyl-2-oxazolidinone, 5-methyl-3-cyclohexyl-2-oxazolidinone, 4,5-dimethyl-3-cyclohexyl-2-oxazolidinone. 3,4,5-trimethyl-2-oxazolidinone, 3-butyl-4-ethyl-5-methyl-2-oxazolidinone, 5,5-diethyl-3-methyl-2-oxazolidinone or 3-(hydroxyethoxyethyl)-2-oxazolidinone. The ink composition of claim 1 or 2 wherein the oxazolidinone compound is present in the ink in an amount of from 0.5 to 80 percent by weight of the ink composition. The ink composition of any of claims 1 to 3 wherein the oxazolidinone compound is present in the ink in an amount of from 5 to 30 percent by weight of the ink composition. A printing process which comprises the step of incorporating into an ink jet printing apparatus the ink composition of any of claims 1 to 4. The printing process of claim 5 wherein 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.

Inventors: SCHWARZ WILLIAM M JR, SCHWARZ, WILLIAM M., JR.
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1998
Main classification: C09D11
IPC codes: C09D11