Ink jet ink compositions and processes for high resolution and high speed printing

Abstract: A thermal ink jet printing comprises incorporating into a thermal ink jet printer at least one ink jet ink with an ink composition comprising water; a colorant of a dye or pigment; a hydroxyamide derivative having at least one hydroxyl group and at least one amide group or a reaction product of oxyalkylene(s) and the said hydroxyamide derivative; a sulfur-containing humectant that is a sulfoxide or a sulfone or a thiol derivative. Printing with the ink jet ink is according to digital signals with at least one printhead which is selected from a group consisting of single, partial-width, and full-width array printheads using a checkerboard or single pass method onto a print substrate either with or without the presence of heat for drying. The ink jet ink has a good latency, long-term jetting stability, and good image quality on plain papers when it is used in a high resolution thermal ink jet printhead including a 600 spi printhead.

Description: The present invention is directed to aqueous ink compositions. More specifically, the present invention is directed to aqueous ink compositions particularly suitable for use in high speed and high resolution thermal ink jet printing processes, having long-term jetting stability and providing excellent pnnt quality. Ink jet printing is a non-impact printing method that produces droplets of ink that are deposited on a substrate such as paper or transparent film in response to an electronic digital signal. Thermal or bubble jet drop-on-demand ink jet printers have found broad application as output for personal computers in the office and in the home. In existing thermal ink jet printing processes, the printhead typically comprises one or more ink jet ejectors, each ejector including a channel communicating with an ink supply chamber, or manifold, at one end and having an opening at the opposite end, referred to as a nozzle. A thermal energy generator, usually a resistor, is located in each of the channels, at a predetermined distance from the nozzles. The resistors are individually addressed with a current pulse to momentanly vaporize the ink within the respective channel to form a bubble that expels an ink droplet As the bubble grows, the ink rapidly bulges from the nozzle and is momentanly contained by the surface tension of the ink as a meniscus. This is a very temporary phenomenon, and the ink is quickly propelled toward a print substrate. As the bubble begins to collapse, the ink still in the channel between the nozzle and bubble starts to move towards the collapsing bubble, causing a volumetric contraction of the ink at the nozzle and resulting in the separation of the bulging ink from the nozzle as a droplet. The acceleration of the ink out of the nozzle while the bubble is growing provides the momentum and velocity for propelling the droplet in a substantially straight line direction towards a print substrate, such as a piece of paper. Because the droplet of ink is emitted only when the resistor is actuated, this type of thermal ink jet printing is known as "drop-on-demand" printing. Other types of ink jet printing, such as piezoelectric, acoustic and continuous-stream ink jet printings, are also known. A major concern with all ink jet printers, and high resolution ink jet printers in particular, is plugging or clogging of nozzles during operation and between operations. This is caused by evaporation of water or an organic solvent (humectant) or both from the opening of the nozzle. In dye-based inks, this can cause crystallization or precipitation of soluble components such as dye or solid additives as well as increase viscosity of the ink liquid. In pigment-based inks, this evaporation can cause precipitation of the pigment particles, flocculation or aggregation of the pigment particles, or precipitation of solid additives as well as a viscosity increase of the ink liquid. Initial evaporation generally causes an increase in viscosity, which affects the ability of the heater (i.e., a thermal energy generator or a resistor) of a printhead to fire a drop of ink through a nozzle. The inception of plugging may cause distortion of the image or alphanumeric characters being printed by the printhead. This may appear as a drop of ink that is displaced from its intended position (misdirectionarity). On some occasions the drop may even reach its intended position but at a lower drop volume producing a lower optical density image. Ultimately, the plugged nozzle may fail to fire entirely and no image will be generated. An important requirement for ink jet inks, especially for pigment-based inks, is for the pigment particles to remain stable and uniformly dispersed in the ink throughout the life of the ink jet cartridge. Dye-based ink jet inks suffer from deficiencies in waterfastness (water resistance) and lightfastness (light resistance) after being pnnted on various substrates. Pigments provide an image, on a wide variety of substrates, having high optical density and sharp edges with very good waterfastness and lightfastness. Therefore, pigments are a preferred alternative to dyes in an ink jet ink, provided that the pigment particles and dispersions can be made stable to prevent undesired flocculation and/or aggregation and settling. Great effort has been made in attempts to provide both dye-based and pigment-based ink jet inks having acceptable latency and stability for high speed and high resolution ink jet printing. However, there continues to have a demand for inks having the above-mentioned desirable characteristics. Two known problems in ink jet printing are 'paper cockle' and paper curl'. Paper cockle is a distortion in which bumps, indentations and other irregularities are randomly produced on the pnnted paper, giving the paper a "wrinkled" or "wavy" appearance. Curl is a phenomenon in which the edges of the paper migrate towards the center of the paper. In extreme cases, curl causes the paper to assume the shape of a scroll. The direction of curl may be on the printed side of the paper, or it may be on the non-printed side (the latter being known as "reverse curl"). Another problem encountered in employing aqueous ink jet compositions is kogation or heater deposit. Occasionally, as ink in an ink jet printhead is heated and vaporized, the ink will undergo thermal breakdown. This decomposition leads to residue deposition on the resistor's (heater's) surface in an ink jet printing process known in the art as "kogation." Such heater deposits insulate the thermal heating of ink drops on the resistor surface, thereby causing reduced bubble formation, decreased ejection velocity of the ink drops, and reduced drop volume delivered to the substrate as well as jetting failure. Consequently, print quality is reduced and failure in bubble formation may result in preventing the ink jet printer to print properly. Thus, ink jet ink compositions employing thermally stable humectants and ink components that not only can increase ink latency but also reduce the rate of crusting and deposit on the heater are particularly desirable. The use of such thermally stable humectants in ink jet ink compositions allow the ink jet printing to be earned out properly for a long period of time without failure (i.e. with good long-term jetting stability). It also reduces the cost of frequent replacement of a printhead or a full-width array pnnthead (printbar) which is expensive. In a color ink jet printing apparatus, a phenomenon known as inter-color bleed may also occur. This phenomenon is the bleeding of one color portion of the image into another portion of the neighboring image of a different color. This becomes most apparent when a black image is imaged immediately adjacent to an area pnnted with a color such as cyan, magenta or yellow. In such a case, the black ink will be seen to bleed into the color area or vice versa to create a conspicuous print defect. This effect is described in US-A-5,371,531. Thus, there is a need for ink jet ink compositions to have not only the aforementioned desired attributes but also reduced inter-color bleeding in a multi-color ink jet pnnting system. EP-A-602,914 discloses an ink composition comprising water, a water soluble dye, a first component selected from the group consisting of sulfones and mixtures thereof, and a second component selected from the group consisting of (a) cyclic amines having at least one hydrogen atom bonded to a nitrogen atom; (b) cyclic amides having at least one hydrogen atom bonded to a nitrogen atom; (c) diamides having at least one hydrogen atom bonded to a nitrogen atom; (d) polyalkoxy-substituted amides having at least one hydrogen atom bonded to a nitrogen atom; (e) polyimine-substituted amides having at least one hydrogen atom bonded to a nitrogen atom; and (f) mixtures thereof, wherein at least one of the first and second components is a solid at 25°C. The ink jet ink compositions of the present invention fulfill the above needs without any deleterious effects such as inducing undesired plugging of the pnnthead nozzles or inferior pnnt quality. The present invention provides an aqueous ink jet ink composition according to claim 1 and a thermal ink jet printing process according to claim 7. Preferred embodiments of the invention are set forth in claims 2 to 6. The present invention also relates to ink jet ink compositions further comprising a colorant such as a water soluble or dispersible dye or pigment that can be coupled with a microwave dryer to give high quality images with good drying, low intercolor bleeding, and without an undesired smeanng problem. The ink jet ink compositions of the present invention may optionally comprise such additives as a pH buffering agent, a water soluble monovalent or multi-valent cationic salt for coupling with a microwave dryer and/or for reducing intercolor bleeding (anti-intercolor bleeding agent), a jetting aid, an anti-curl agent, an ink penetrant, a water soluble biocide, and other desired chemical additives (ink additives). The ink jet inks of the present invention may suitably be prepared as black or color ink jet inks for high quality, high speed, and high resolution (such as 400 spi, 600 spi, etc.) ink jet printing with single, partial-width, or full-width array printheads. Thus, the present invention provides ink jet inks that enhance (1) latency, (2) the ability for high speed printing, (3) the reliability and desired jetting performance of an ink jet ink printhead, and (4) the drying and pnnt quality of images, as well as reduce (1) intercolor bleeding, (2) smear, (3) paper curl, and (4) the cost of frequent replacement of a printhead or pnntbar due to kogation. The hydroxyamide derivatives herein are soluble or miscible in water and they are used in inks as a humectant, an anti-curl agent, an anti-clogging agent, and a possible solvent for some dyes or a dispersing medium for some pigments. They can be employed in inks in conjunction with other known humectants such as glycol type humectants and sulfur-containing humectants, which include, but not limited to, glycol derivatives such as ethyleneglycol, diethyleneglycol. propyleneglycol, dipropyleneglycol, polyethyleneglycol, polypropyleneglycol, and the like as well as sulfoxide and sulfone derivatives to provide inks with long latency and long-term jetting stability Inks comprising a hydroxyamide denvative and a sulfur-containing humectant are especially useful when a high resolution ink jet printhead (e.g., 400 spi, 600 spi thermal ink jet printhead) is used. The ink jet inks of the present invention can also be formulated to have an ammonium or metal salt including a monovalent or multi-valent metal salt so that they can be used either with or without a microwave dryer (a heating device) to avoid intercolor bleeding and smear. This allows ink jet printing on a substrate at a fast speed. The hydroxyl and amide functional groups of the aforementioned hydroxyamides are polar functional groups that are compatible with water and can interact with water and hydroxyl groups of cellulosic materials including papers (printing substrates). These unique properties allow the hydroxyamide derivatives to be used in ink jet inks of this invention to reduce the evaporation of water, to increase latency, and to bond with the hydroxyl groups of cellulosic substrates (in paper, fibers, textile material, and other polar substrates) through hydrogen bonding to reduce cockle and curt. Examples of useful hydroxyamide derivatives used in this invention include acetyldiethanolamine (C 6 H 13 NO 3 , two hydroxyl groups and one amide group in the compound), propionyldiethanolamine (C 7 H 15 NO 3 , two hydroxyl groups and one amide group in the compound), N-N-bis(2-hydroxyethyl)benzamide (two hydroxyl groups and one amide group with an aromatic moiety), and N,N-bis(hydroxyethyl)isonicotinamide (two hydroxyl groups and one amide group, with a heterocyctic moiety). They can also react with an oxyalkylene (alkyleneoxide) including ethyleneoxide, propyleneoxide and a mixture of both oxyalkylenes through their hydroxyl groups to give rise to new hydroxyamide derivatives (having two or more hydroxyl groups and at least one amide group). Examples of useful hydroxyamide derivatives used in this invention further include N,N'-Bis(2-hydroxyethyl)oxamide (two amide groups and two hydroxyl groups in the compound), tris(3,5-di-tert-butyl)-hydroxybenzyl)isocyanurate (three hydroxyl groups and three amide groups in the compound), and mixtures thereof. Inks of the present invention, in embodiments, may also comprise isomers of the aforementioned hydroxyamide denvatives, their reaction products with oxyalkylenes, and mixtures thereof. In embodiments of the present invention, the hydroxyamide derivatives may be incorporated into the ink jet inks in an amount of from 0.01 to 40% by weight of total ink weight. Preferably. the content of the hydroxyamide derivative in an ink jet ink is from 1 to 30% by weight of total ink weight, and more preferable from 5 to 25% by weight of total ink weight. although it can be outside of this range. The ink jet inks of the present invention also comprises a water soluble or miscible sulfur-containing humectant or co-solvent which is selected from a sulfoxide or sulfone or a thiol derivative. The sulfoxide, sulfone, and thiol derivatives can be linear, cyclic, aromatic or heterocyclic type of materials. For example, sulfoxide derivatives suitable for use in the present invention include alkylphenyl sulfoxide derivatives and dialkylsulfoxide derivatives including dimethylsulfoxide, diethylsulfoxide, methylethylsulfoxide, dipropylsulfoxide, and propylethylsulfoxide. Sulfone derivatives suitable for use in the present invention include sulfolane (tetramethylene sulfur dioxide); methylsulfolane; dialkyl sulfone derivatives including dimethylsulfone, methylethylsulfone, diethylsulfone, and dipropylsulfone; and alkyl phenyl sulfone derivatives including methylphenylsulfone, and ethylphenylsulfone. Thiol derivatives suitable for use in the present invention include alkylthiols and aromatic thiols such as ethylmercaptan(ethylthiol), propylmercaptan(propanethiol), butylmercaptan, and phenylthiols; thioglycol derivatives including thioethyleneglycol, thiodiethyleneglycol, thiopolyethyleneglycols, thiopropyleneglycol, thiodipropyleneglycol, and thiopolypropyleneglycols, as well as mixtures thereof. The inks compnsing the hydroxyamide derivative(s) and the aforementioned sulfoxide, sulfone, and thiol denvatives provide exceptionally good latency for a high resolution printhead in a 600 spi ink jet pnnter. When a 600 spi printhead is used, the latency is generally desired to be greater than 10 seconds and preferably greater than 15 seconds. Even more preferably, ink jet inks of the present invention have latencies of 20 or 30 seconds or more. Longer ink latency allows the ink to be functioned properly in an ink jet pnnter (especially a high resolution ink jet printer, for example 600 spi) with less stringent maintenance requirements (e.g., required low ink spitting frequency, etc.) and more robust printing operation. In embodiments of the present invention, the humectant or co-solvent of the aforementioned sulfoxide and sulfone derivatives is included in the ink jet inks in an amount of from 0 to 40% by weight of total ink weight, although it can also be outside of this range. Preferably, the content of the sulfur-containing humectant is from 1 to 30% by weight of total ink weight, and more preferably from 2 to 30% by weight of total ink weight. The ink jet inks of the present invention may also optionally include any of the various known water miscible or soluble organic compounds as humectants or co-solvents other than sulfoxide and sulfone derivatives. Suitable organic compounds include glycol denvatives such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethyleneglycol, tetraethyleneglycol, pentaethyleneglycol, polyethylene glycol, tripropyleneglycol, tetrapropyleneglycol, polypropylene glycol; triols such as glycerine, trimethylolpropane, 1,3,5-triols, 1,2,5-triols, and reaction products of all aforementioned glycol and triol derivatives with ethyleneoxide and alkylethyleneoxides such as propyleneoxide; amides such as 2-pyrrolidinone, N,N-dimethylforamide, N-methylacetamide, N,N-dimethylacetamide, caprolactam; urea and its derivatives; inner salts including betaine; ethers such as glycol ethers including carbitol derivatives such as butylcarbitol, cellusolve; polyglycolether denvatives; carboxylic acids and salts; alcohol derivatives including 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, n-hexanol, n-petanol, n-butanol, n-propanol, isopropanol, ethanol, methanol; amino alcohol derivatives; derivatives and isomers thereof; and their mixtures thereof. The ink jet inks of the present invention include both fast drying and slow drying inks. The slow drying inks generally have a surface tension which is equal to or greater than 4.5x10 -4 N/cm (45 dynes/cm), while fast drying inks generally have a surface tension less than 4 5x10 -4 N/cm (45 dynes/cm). The slow drying inks tend to give good edges and sharp images on plain papers with a slow printing speed. The fast drying inks are capable of pnnting at a fast speed but with a slightly inferior print quality. The fast drying ink of this invention can comprise a penetrant that will avoid inter-color bleeding and increase ink drying speed. The penetrant gives the fast drying ink a lower surface tension, less than 4 5x10 -4 N/cm (45 dynes/cm) and preferably less than 4x10 -4 N/cm (40 dynes/cm). Preferably, the fast drying ink jet inks of the present invention have a surface tension of from 2.2x10 -4 to 4.5x10 -4 N/cm (22 to 45 dynes/cm), and more preferably from 2.6x10 -4 to 4.5x10 -4 N.cm (26 to 45 dynes/cm). The viscosity of the inks of this invention at 25°C is usually less than 20 mPa.s (cps), preferably from 1 mPa.s (cp) to 10 mPa.s (cps), and more preferably from 1 mPa.s (cp) to 5 mPa.s (cps). Penetrants suitable for use in the present invention include hydroxyether derivatives, including alkylcellusolves, propyleneglycol butyl ether, dipropyleneglycol butyl ether, and tripropyleneglycol methyl ether, and alkylcarbitols such as hexylcarbitol or butylcarbitol, polyethyleneglycol ether derivatives (e.g., one or two hydroxyl group(s) of polyethyleneglycol is replaced by a functional group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, dodecyl, lauryl, stearyl, phenyl, alyklphenyl (e.g., octylphenyl, nonylphenyl )); and polypropyleneglycol ether derivatives (e.g., one or two hydroxyl group(s) of polyethyleneglycol is or are replaced by a functional group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, dodecyl, lauryl, stearyl, phenyl, alyklphenyl); alcohol derivatives (e.g. methanol, ethanol, isopropanol, butanol, pantanol, hexanol, octanol, as well as their isomers); alkyl and cyclic amide derivatives including hexanoic acid amide, octanoic acid amide, N-cyclohexylpyrrolidinone, N-hexylpyrrolidinone, N-ethylpyrrolidinone; various surfactants having hydrophobic and hydrophilic moieties in the molecule including nonionic, cationic, and anionic types surfactants; and mixtures thereof. The ink jet ink of the present invention also comprises a colorant. The colorant can be selected from any of the suitable colorants known in the art and preferably is either an anionic or cationic dye or a pigment. The pigment may be present with or without a dispersing agent. For example, chemically modified pigments that have water compatible or ionized functional group(s) such as anionic carboxylate and sulfonate group(s) as well as cationic ammonium group(s) can be dispersed in aqueous inks without a dispersing agent. In addition, the colorant for the ink compositions of the present invention may, in embodiments, be a mixture of one or more pigments and/or dyes. The color of the mixed pigments and/or dyes can be used to adjust color gamut and hue of ink jet images. In embodiments of the present invention where dyes are used, the dye is present in the ink jet ink in any effective amount to provide a desired color. Typically the dye is present in an amount of from 0 to 20% by weight of total ink weight, and preferably from 0.1 to 10% by weight of total ink weight, although the amount can be outside this range. A mixture of dyes in the proportions desired to obtain a specific shade may also be employed. Similarly, in embodiments of the present invention where pigments are used, the pigment may be present in the ink jet ink in any effective amount to provide needed color strength. Typically the pigment is present in an amount of from 0 to 15% by weight of total ink weight and preferably from 0.1 to 10% by weight of total ink weight, and more preferably from 1 to 8 percent by weight of total ink weight, although the amount can be outside of this range. Where both dyes and pigments are incorporated into the ink jet ink composition, the weight percentage of the combined colorant may be adjusted accordingly. The ink compositions of this invention can comprise a colorant such as water soluble dyes including anionic and cationic dyes. Those dyes can be Basic, Acid, Direct, and Reactive dyes. Examples of suitable dyes include Food Black No. 1. Food Black No. 2. Food Red No. 40, Food Blue No. 1, Food Yellow No. 7; FD & C dyes; Acid Black dyes (No. 1, 7, 9, 24, 26, 48, 52, 58, 60, 61, 63, 92, 107, 109, 118, 119, 131, 140, 155, 156, 172, 194); Acid Red dyes (No. 1, 8, 32, 35, 37, 52, 57, 92, 115, 119, 154, 249, 254, 256), Acid Blue dyes (No. 1, 7, 9, 25, 40, 45, 62, 78, 80, 92, 102, 104, 113, 117, 127, 158, 175, 183, 193, 209); Acid Yellow dyes (No. 3, 7, 17, 19, 23, 25, 29, 38, 42, 49, 59, 61, 72, 73, 114, 128, 151); Direct Black dyes (No. 4, 14, 17, 22, 27, 38, 51, 112, 117, 154, 168), Direct Blue dyes (No. 1, 6, 8, 14, 15, 25, 71, 76, 78, 80, 86, 90, 106, 108, 123, 163, 165, 199, 226); Direct Red dyes (No. 1, 2, 16, 23, 24, 28, 39, 62, 72, 227, 236); Direct Yellow dyes (No. 4, 11, 12, 27, 28, 33, 34, 39, 50, 58, 86, 100, 106, 107, 118, 127, 132, 142, 157); anthraquinone dyes, monoazo dyes, disazo dyes, phthalocyanine derivatives, including vanous phthalocyanine sulfonate salts, aza annulenes, formazan copper complexes, tnphenodioxazines, Bernacid Red 2BMN; Pontamine Brilliant Bond Blue A; Pontamine; Cibracron Brilliant Red 38-A (Reactive Red 4), available from Aldnch Chemical; Drimarene Brilliant Red X-2B (Reactive Red 56), available from Pylam, Inc.; Levafix Brilliant Red E-4B, available from Mobay Chemical; Levafix Brilliant Red E-6BA, available from Mobay Chemical; Procion Red H8B (Reactive Red 31), available from ICI America; Direct Brilliant Pink B Ground Crude, available from Crompton & Knowles; Cartasol Yellow GTF Presscake, available from Sandoz, Inc.; Cartasol Yellow GTF Liquid Special 110, available from Sandoz, Inc.; Yellow Shade 16948, available from Tncon. Basacid Black X34 (BASF X-34), available from BASF, Carta Black 2GT, available from Sandoz. Inc.; Neozapon Red 492 (BASF); Orasol Red G (Ciba-Geigy); Direct Brilliant Pink B (Crompton-Knolls); Aizen Spilon Red C-BH (Hodogaya Chemical Company); Kayanol Red 3BL (Nippon Kayaku Company); Levanol Brilliant Red 3BW (Mobay Chemical Company); Levaderm Lemon Yellow (Mobay Chemical Company); Spirit Fast Yellow 3G; Aizen Spilon Yellow C-GNH (Hodogaya Chemical Company); Sinus Supra Yellow GD 167; Cartasol Brilliant Yellow 4GF (Sandoz); Pergasol Yellow CGP (Ciba-Geigy); Orasol Black RL (Ciba-Geigy); Orasol Black RLP (Ciba-Geigy); Savinyl Black RLS (Sandoz); Dermacarbon 2GT (Sandoz); Pyrazol Black BG (ICI); Morfast Black Concentrate A (Morton-Thiokol); Diazol Black RN Quad (ICI); Orasol Blue GN (Ciba-Geigy); Savinyl Blue GLS (Sandoz); Luxol Blue MBSN (Morton-Thiokol); Sevron Blue 5GMF (ICI); Basacid Blue 750 (BASF); Bemacid Red, available from Berncolors, Poughkeepsie, N.Y.; Pontamine Brilliant Bond Blue; Berncolor A.Y. 34; Telon Fast Yellow 4GL-175; BASF Basacid Black SE 0228; various Reactive dyes, including Reactive Black dyes, Reactive Blue dyes, Reactive Red dyes including Reactive red 180, Reactive Yellow dyes including Reactive yellow 37, as well as mixtures thereof. The pigments can be black, cyan, magenta, yellow, red, blue, green, brown, as well as mixtures thereof. Examples of suitable pigments include various carbon blacks such as channel black, furnace black, lamp black, Raven® 5250, Raven® 5750, Raven® 3500 and other similar carbon black products available from Columbia Company, Regal® 330, Black Pearl® L, Black Pearl® 1300, and other similar carbon black products available from Cabot Company, Degussa carbon blacks such as Color Black® series, Special Black® series, Printtex® series and Derussol® carbon black dispersions available from Degussa Company, Hostafine® senes such as Hostafine® Yellow GR (Pigment 13), Hostafine® Yellow (Pigment 83), Hostafine® Red FRLL (Pigment Red 9), Hostafine® ( Rubine F6B (Pigment 184), Hostafine® Blue 2G (Pigment Blue 15.3), Hostafine® Black T (Pigment Black 7), and Hostafine® Black TS (Pigment Black 7), available from Hoechst Celanese Corporation, Normandy Magenta RD-2400 (Paul Uhlich), Paliogen Violet 5100 (BASF), Paliogen® Violet 5890 (BASF), Permanent Violet VT2645 (Paul Uhlich), Heliogen® Green L8730 (BASF), Argyle Green XP-111-S (Paul Uhlich), Bnlliant Green Toner GR 0991 (Paul Uhlich), Heliogen® Blue L6900, L7020 (BASF), Heliogen® Blue D6840, D7080 (BASF), Sudan Blue OS (BASF), PV Fast Blue B2G01 (American Hoechst), Irgalite Blue BCA (Ciba-Geigy), Paliogen® Blue 6470 (BASF), Sudan III (Matheson, Coleman, Bell), Sudan II (Matheson, Coleman, Bell), Sudan IV (Matheson, Coleman, Bell), Sudan Orange G (Aldrich), Sudan Orange 220 (BASF), Paliogen® Orange 3040 (BASF), Ortho Orange OR 2673 (Paul Uhlich), Paliogen® Yellow 152, 1560 (BASF), Lithol Fast Yellow 0991K (BASF), Paliotol Yellow 1840 (BASF), Novoperm Yellow FG 1 (Hoechst), Permanent Yellow YE 0305 (Paul Uhlich), Lumogen Yellow D0790 (BASF), Suco-Gelb L1250 (BASF), Suco-Yellow D1355 (BASF), Hostaperm Pink E (American Hoechst), Fanal® Pink D4830 (BASF), Cinquasia Magenta (DuPont), Lithol Scarlet D3700 (BASF), Toluidine Red (Aldrich), Scarlet for Thermoplast NSD PS PA (Ugine Kuhlmann of Canada), E.D. Toluidine Red (Aldrich), Lithol® Rubine Toner (Paul Uhlich), Lithol® Scarlet 4440 (BASF), Bon Red C (Dominion Color Company), Royal Brilliant Red RD-8192 (Paul Uhlich), Oracet Pink RF (Ciba-Geigy), Paliogen Red 3871K (BASF), Paliogen® Red 3340 (BASF), and Lithol® Fast Scarlet L4300 (BASF). Other useful pigments can also be selected. The preferred pigments for the ink jet inks of the present invention are nontoxic and AMES test (a mutagenic test) negative materials that include nonmutagenic and noncarcinogenic pigments for safety reasons. For example, it is desired to have dyes and pigments, including carbon blacks and color pigments, that have a very low concentration of polyaromatic hydrocarbons, which are known to be carcinogenic or mutagenic. For illustrative purposes, nitropyrene, pyrene, tetracene, pentacene, and many other polyaromatic hydrocarbons in many commercial carbon blacks and color pigments are considered to be toxic at a concentration greater than 5 parts per million Thus, it is desirable to limit the amount of such toxic polyaromatic hydrocarbons in the pigments to less than 5 parts per million for the preparation of nontoxic ink jet inks. Many commercial carbon blacks and colored pigments have a concentration of polyaromatic hydrocarbons exceeding 5 part per million and, therefore, the inks derived from such pigments are generally considered to be toxic or failing to pass the AMES test. However, many nontoxic carbon blacks and color pigments including Raven® 5250, Raven® 5750, Regal® 330, Black Pearl® 1300, Black Pearls L, Vulcan® XC-7, Hostapern® pink E, Hostaperm® blue (a phthalocyanine derivative) and other pigments are generally used in toners and other imaging applications. Those carbon blacks and color pigments usually have a polyaromatic hydrocarbon content of less than 1 part per million. They do not show positive response in the AMES test and are considered to be safe in toner and ink jet ink applications. Preferably, the pigment particle size is as small as possible to enable a stable colloidal suspension of the particles in the liquid vehicle with good color strength and to prevent clogging of the ink channels or nozzle openings when the ink is used in a thermal ink jet printer. Preferred particle average diameters are generally from 0.001 to 3 micrometers, although the particle size can be outside these ranges in embodiments. A preferred average pigment particle size in the inks of this invention includes particles having at least 50% of the particles being below 0.3 micrometer with no remaining particles being greater than 3.0 micrometer (measured on a Hodaka CAPA 700 Particle Size Analyzer). More preferably, the average pigment particle size includes particles having at least 50% of the particles being below 0.3 micrometer with no remaining particles being greater than 1.0-1.2 micrometer. In embodiments of the present invention, the pigment may be dispersed in the ink with one or more dispersants. The dispersants can be anionic, cationic, and nonionic types. Some preferred dispersants are ionic dispersants that have both ionic (capable of ionization in water) and hydrophobic (affinity for pigments) moieties. Suitable dispersants include anionic dispersants, including polymers and copolymers of styrene sulfonate salts (such as Na + , Li + , K + , Cs + , Rb + , substituted and unsubstituted ammonium cations) and naphthalene sulfonate salts, (such as Na + , Li + , K + , Cs + , Rb + , substituted and unsubstituted ammonium cations); copolymers of unsubstituted and substituted (e.g., alkyl, alkoxy, substituted naphthalene derivatives) naphthalene sulfonate salts (such as Na + , Li + , K + , Cs + , Rb + , substituted and unsubstituted ammonium cations) and an aldehyde derivative (such as alkyl aldehyde derivatives including formaldehyde, acetaldehyde, propylaldehyde), polymers and copolymers comprising acrylic acid salts, or methacrylic acid salts, or maleic acid salts, and mixtures thereof. They can be either in solid form or water solutions. Examples of such dispersants include commercial products such as Versa® 4, Versa® 7, Versa® 77 (National Starch and Chemical Co.); Lomar® D (Diamond Shamrock Chemicals Co.); Daxad® 19, Daxad® K (W. R. Grace Co.); and Tamol® SN (Rohm & Haas). Some of the preferred dispersants comprise naphthalene sulfonate salts, especially a condensation or reaction products of naphthalenesulfonic acid and formaldehyde, and its salts (such as Na + , Li + , K + , Cs + , Rb + , substituted and unsubstituted ammonium cations) as well as polymers and copolymers compnsing vanous carboxylic salts. Also, nonionic dispersants or surfactants can be used in ink jet inks of the present invention, such as ethoxylated monoalkyl or dialkyl phenols including Igepal® CA and CO series matenals (Rhone-Poulenc Co.); and Triton® series materials (Union Carbide Company). These nonionic surfactants or dispersants can be used alone or in combination with the aforementioned anionic or cationic dispersants. Useful cationic dispersants of this invention generally comprise substituted and unsubstituted ammonium salts. The ink jet inks of the present invention may optionally comprise a water soluble or miscible microwave coupler which can be ionic or nonionic type. The aforementioned hydroxyamide derivatives and their oxyalkylene reaction products used in this invention are nonionic and can be used in ink jet inks to couple with the microwave dryer for effective drying of images on papers and the reduction of smear and intercolor bleeding. Those hydroxyamide derivatives and their condensation products with alkyleneoxides (oxyalkylenes) can function as humectants, anti-curl agents, and/or microwave couplers. They can be used in ink jet inks either with or without an ionic type microwave coupler. The ionic type microwave coupler can be selected from an organic or inorganic salt that allows an ink to be dned quickly by a microwave heating device. The microwave coupler can be, for example, a salt that provides the ink jet ink with a desirable conductivity and coupling efficiency. The salts or ionic compounds exhibit a high degree of ionization in aqueous inks with good electrical conductivity and are capable of coupling with a heating device such as a microwave device. These ionic compounds typically include metal and ammonium salts of inorganic and organic acids with cations and anions. Typical cations of salts include H + , NH 4 + , Cs + , K + , Na + , Li + , Ca 2+ , Mg 2+ , Zn 2+ , Ni 2+ , Mn 2+ , Co 2+ , Sr 2+ , Cd 2+ , Ba 2+ , Fe 2+ , Cu 2+ , Ga 3+ , In 3+ , Cr 3+ , Pr 3+ , Nd 3+ , Y 3+ , Al 3+ , Fe 3+ , lanthanide cations, and actinide cations. The anions of those salts include inorganic and organic anions such as I - , Br - , Cl - , F - , OH - , NO 3 - , SO 4 2- , CH 3 CO 2 - , CH 3 CH 2 CO 2 - , C 6 H 5 CO 2 - , C 6 H 5 SO 3 - , and various ethylenediaminetetraacetic acid (EDTA) anions. Metal salts of monovalent and multi-valent salts can also be used in ink jet inks for reduction of intercolor bleeding (bleed near the border of two different inks) either through microwave heating of the images or chemical interaction with anionic type colorants (e.g., anionic dyes, pigments stabilized with anionic dispersants, pigments with an anionic functional group on the surface) in a multi-color ink jet printing process. The use of those ammonium and metal salts are desirable when they are compatible with components used in this invention including water, hydroxyamide derivatives, sulfur-containing humectants such as sulfoxides and sulfones, or other humectants including glycol derivatives, polyethyleneglycols and polypropyleneglycols, colorants including dyes and pigments, and other optional ink additives. They are chosen so that they will not cause a latency or a jetting problem, especially for a high resolution pnnthead. In embodiments of the present invention, the metal and ammonium salts of inorganic and organic acids with ionizable cations and anions in aqueous inks can be included in the ink jet inks in an amount of from 0 to 15% by weight of total ink weight, and preferably in an amount of from 0 to 8% by weight of total ink weight, although they can be outside this range. The ink jet inks of the present invention may optionally include a jetting aid such as polyethyleneoxide. A preferred polythyleneoxide is one having a weight-average molecular weight of about 18,500 at a concentration of 0.001-1.0% by weight of inks, and preferably a concentration of less than 0.5% by weight. The jetting aid provides smooth jetting or jetting with low jitters. Other desired chemical additives including surfactants, water soluble polymers, pH buffers, biocides, chelating agents (EDTA), and other known additives can also be optionally used in inks of this invention. Such additives can generally be added to ink jet inks of the present invention in known amounts for their known purpose. Surfactants or wetting agents can be added to the ink to control ink wetting and surface tension. These additives may be of the anionic or cationic or nonionic types. Suitable surfactants and wetting agents include Tamol SN®, Tamol LG®, and those of the Triton® series (Rhom and Hass Co.); those of the Marasperse® series and those of the Igepal® senes (Rhone-Poulenc Co., formerly from GAF Co.); those of the Briji® Series (ICI Amenca Inc.) including Bnji® 30, Briji® 35, Briji® 52, Briji® 56, Briji® 58, Briji® 72, Briji® 76, Briji® 78, Briji® 92, Briji® 96, and Briji® 98; those of Surfynol® Series (Air Product Co.); those of the Tergitol® senes (Union Carbide Co.), and those of the Duponol® series (E.I. Du Pont de Nemours & Co.), sodium lauryl sulfate; sodium dodecyl sulfate; sodium octyl sulfate; Emulphor® ON 870 and ON 877 (GAF); Igepal® Senes (Rhone-Poulenc Co.) surfactants including Igepal® CO-630, Igepal® CO-530, Igepal® CA-630, and Igepal® CA-530; Duponol Series (DuPont Co.); and other commercially available surfactants. These surfactants and wetting agents may be present in the inks in effective amounts, generally from 0 to 10 percent by weight of total ink weight, and preferably from 0.0001 to 8 percent by weight of total ink weight, and more preferably from 0.0001 to 5 percent by weight of total ink weight, although the amount can be outside these ranges. Polymeric chemical additives can also be added to the ink jet inks of the present invention to enhance the viscosity of the ink. Suitable polymeric additives include water soluble polymers such as Gum Arabic, polyacrylate salts, polymethacrylate salts, polyvinyl alcohols, hydroxypropylcellulose, hydroxyethylcellulose, polyvinylpyrrolidinone, polyvinylether, starch, polysaccharides, polyethyleneimines being derivatized with ethylene oxide and propylene oxide, such as the Discole® series (DKS International); and the Jeffamine® series (Texaco). Polymeric additives may be present in the ink jet inks of the present invention in amounts of from 0 to 10 percent by weight of total ink weight, preferably from 0.001 to about 8 percent by weight of total ink weight, and more preferably from 0.01 to 5 percent by weight of total ink weight, although the amount can be outside these ranges. Other optional additives for the ink jet inks of the present invention include biocides such as Dowicil 150, 200, and 75, benzoate salts, sorbate salts, and Proxcel® (available from ICI). When used in inks, such biocides are generally present in an amount of from 0 to 10 percent by weight of total ink weight, preferably from 0.001 to 8 percent by weight of total ink weight, and more preferably from 0.01 to 4.0 percent by weight of total ink weight, although the amount can be outside these ranges. Ink jet inks of the present invention may also include pH controlling agents or pH buffering agents. Suitable pH controlling agents include acids, bases, phosphate salts, carboxylate salts, inner salts with cation and anion in a molecule, sulfite salts and amine salts. When used in inks, such pH controlling agents are generally present in an amount of from 0 to 10 percent by weight of total ink weight, preferably from 0.001 to 5 percent by weight of total ink weight, and more preferably from 0.01 to 5 percent by weight of total ink weight, although the amount can be outside these ranges. Other suitable chemical additives are chelating agents including EDTA (ethylene diamine tetraacetic acid), HEEDTA (N-(hydroxyethyl)ethylenediaminetetracetate), NTA (nitrolacetate), and DTPA (diethylenetriaminepentaacetic acid), as well as their salts, typically present in an amount of from 0.001 to 10 percent by weight of total ink weight and preferably from 0.001 to 5 percent by weight of total ink weight, although the amount can be outside of these ranges. The ink jet inks of embodiments of the present invention possess excellent latency. Generally, the inks demonstrate latency of at least 5 seconds, and preferably on the order of 20 seconds or more, when a 600 spi printhead is employed. Long latency of an ink jet ink is preferred because the ink does not clog the ink nozzles easily and requires less frequent ink spitting or printhead maintenance. In addition, the ink jet inks of this invention have excellent long-term jetting stability (e.g, jetting greater than 1 x 10 8 drops), thus, allowing the printhead or pnntbars to be used for a long period of time. This reduces the cost of ink jet printing operation and maintenance. The use of ink jet inks of the present invention also provides the capability of a fast speed ink jet pnnting (e.g., more than 18 pages per minute of multi-color ink jet printing) especially when partial-width or full-width pnntheads are employed. The capability of fast speed multi-color ink jet printing of this invention far exceeds that of the current state-of-the-art commercial multi-color ink jet printers. The ink jet pnnting of the inks of this invention can be carried out in a checkerboard or image-wise single pass method (process). Some ink jet printers such as desk-top pnnters employ mobile printhead(s). A mobile printhead typically comprises a plurality of closely arranged nozzles provided in a small pnnting area. Such a mobile printhead produces partial digital images (e.g., checkerboarding printing method), which when combined form large recognizable images, by sliding along a guide and dispersing ink during each "pass" across a print substrate. This type of ink jet printer usually is a slow speed desk top ink jet printer that is available in the current market. The mobile printhead may also comprise two or more butted printheads (i.e., a partial-width printhead with increasing number of ink nozzles; For example, it can comprise more than 384 nozzles per printhead) such as the one employed in a partial-width array ink jet printer so that more ink can be delivered to a substrate in a single swath as it moves across the print substrate. This type of partial-width ink jet printer will have a higher ink jet printing speed as compared to the aforementioned desk top ink jet printer with a single printhead per ink cartridge. In a multi-color ink jet printer, several pnntheads (e.g., black, cyan, magenta, and yellow) and their corresponding inks can be mounted on a printhead holder and moved across the pnnt substrate. Different color inks are dispersed onto a print substrate when they are moved relative to the print substrate or vice versa. Multi-color image can be obtained by repeated printing. Multi-color ink jet printing using the partial-width pnntheads (e.g., black, cyan, magenta, and yellow printheads with their corresponding inks) increases the printing speed of the checkerboard pnnting process. Other faster ink jet printing such as a single pass ink jet printing or full-width array ink jet printing employs a full-width array printhead comprising a plurality of closely arranged nozzles and ejectors arranged across a width of a print substrate (an array of butted printheads extended to the width of a pnnt substrate; for example, it can comprise more than several thousand ink jet nozzles per pnnthead). These nozzles can disperse ink without several time consuming passes of the pnnthead across the print substrate. The full-width array ink jet pnntheads are usually stationary in the printing process while the print substrate is passing through the pnntheads. Many known full-with array ink jet printheads, processes, and their applications are described in US-A-5,057,854; US-A-4,985,710; US-A-5,098,503; US-A-5,192,959 and US-A-5,432,539. The ink jet inks of this invention can be employed in conjunction with a heater or dryer(e.g., a microwave dryer or device) to perform ink jet printing at a high speed (e.g., equal to or greater than 18 pages per minutes) to produce high quality multi-color images on plain or coated papers without smear or inadequate drying. In another embodiment of this invention, the print substrate used for printing the inks of this invention in an ink jet printing process can be optionally heated before, during, and/or after printing as well as combinations thereof. The print substrate and inks can be optionally heated by various means including radiant heater, electric resistor, heating tape, hot plate, hot roller, microwave device, radiation including heated lamp, and hot air. In this ink jet printing process which involves a set of at least four inks comprising black, cyan, magenta, and yellow inks, the image of the first printing ink (e.g., black ink, or yellow ink, or magenta ink, or cyan ink) is dried on the surface of the print substrate before the deposition of other inks near the border of the first ink. The ink jet inks comprising the hydroxyamide derivatives either with or without the aforementioned ammonium and metal salts can be dried quickly by a heater (e.g. a microwave dryer, radiant heater) to give excellent full color images without undesired smear or intercolor bleeding. The ink jet inks of the present invention may be applied to a suitable pnnt substrate in an image-wise fashion (e.g., using full-width array pnntheads). Application of the ink to the print substrate can be made by any suitable printing process compatible with ink jet inks, such as continuous stream ink jet printing, or drop-on-demand ink jet printing (including piezoelectric, acoustic and thermal ink jet processes). The print substrate employed in this invention can be any substrate compatible with aqueous-based inks, including plain papers, such as Xerox® series 10 paper, Xerox® 4024 paper, and commercial bond papers; coated papers (or special ink jet papers), such as those available from Hewlett-Packard, Canon, Oji Paper Co., and Xerox Corporation; and ink jet transparency materials suitable for aqueous inks or ink jet pnnting processes including those from Artright Co., Hewlett-Packard, Asahi Glass Co., and Xerox Corporation. Aqueous ink jet inks of the present invention provide numerous benefits including low pnnting cost, high image resolution, excellent pnnt quality on a variety of substrates, excellent jetting capability with high drop velocity, longer latency, good drop mass or drop volume that provide optimal optical density, high frequency response to allow for high speed and high resolution printing, excellent printhead recoverability and maintainability, excellent ink jetting stability, and no undesired pnnthead kogation. The ink jet inks of the present invention, which can be used in a high resolution (e.g., 600 spi) ink jet printing process, preferably have a latency of at least greater than 5 seconds and more preferably greater than 10 seconds. The ink jet inks preferably have a frequency response of greater than 3 kilohertz; a transit time of less than 80 microseconds or a drop velocity greater than 6.25 m/s; little or no jitters; and the drop mass can be controlled in the range of 5-35 ng/drop. The ink jet inks also preferably have a long-term ink jetting stability (e g. at least 1 x 10 7 pulses or more than 1 x 10 8 pulses corresponding to 100 million drops). The ink jet inks of the present invention can dry very fast to avoid inter-color bleeding even on plain papers with or without a heating device. The ink jet inks have reduced curl property. In addition, the ink jet inks can be jetted at high speed with partial-width array ink jet pnnthead or full-width array ink jet pnntheads or printbars to give black or color images at a speed of more than 18 pages per minute. EXAMPLES Many ink jet inks were prepared by thoroughly mixing colorants such as dyes or pigments, water, humectants, and selected ink additives followed by pH adjustment with either an acid such as a diluted acetic acid or a base such as a potassium hydroxide solution or a pH buffering agent, and filtration through a series of membrane filters. The compositions and jetting data of these inks are shown below. These examples are not covered by the wording of claim 1. Example I Example IA : A magenta ink jet ink was prepared comprising 24.73% Project Magenta Dye concentrate (ICI, 10% dye solution), 5.93% Acid Red 52 Dye concentrate (10% dye solution), 9.89% Butylcarbitol (2-(2-Butoxyethoxy)ethanol), 1.98% N-cyclohexylpyrrolidinone, 14.84% Sulfolane, 12.86% N-Acetylethanolamine(N-2-hydroxyethylacetamide), 3.0% NH 4 Br, 0.049% Dowicil 200, 0 049% Polyethyleneoxide (Ave. MW = 18,500), and 26.67% Distilled Water. The pH of this ink is 7.01 and the conductivity is 16,900 umhos/cm. Example IB : A yellow ink jet ink was prepared comprising 26.73% Project Yellow Dye concentrate (7.5% dye solution), 19.8% Acid Yellow 17 (10% dye solution), 9.9% Butylcarbitol, 1.98% N-cyclohexylpyrrolidinone, 14.85% Sulfolane, 12.87% N-Acetylethanolamine, 3.0% NH 4 Br, 0.05% Dowicil 200, 0.05% Polyethyleneoxide (Ave. MW = 18,500), and 10 79% Distilled Water. The pH of this ink is 7.02 and the conductivity is 17,000 umhos/cm. Example IC : A cyan ink jet ink was prepared comprising 32.65% Project Cyan Dye concentrate (10.0% Sol), 9 33% Butylcarbitol, 1.87% N-cyclohexylpyrrolidinone, 9.33% Sulfolane, 16.0% N-Acetylethanolamine, 2.33% NH 4 Br, 0.047% Dowicil 200, 0.047% Polyethyleneoxide (MW = 18,500), and 28.36% Distilled Water. The pH of this ink was 7.02 and the conductivity is 13,000 umhos/cm. The color inks and a black ink were tested with a 600 spi thermal ink jet printhead having a channel width of the ink nozzle less than 25 microns. Excellent latency (40-75 sec.) and jetting frequency response (6 kHz) were observed with no undesired kogation or degradation of jetting performance after at least 1 x 10 8 pulses The inks printed very well with a 600 spi ink jet pnnthead on various substrates, including plain papers, coated papers, and transparencies, in either a checkerboard (multi-pass, slow speed) or a single pass mode with a high speed (to produce at least 18 pages/min.) to form good image quality (sharp edges) and excellent resolution. The color inks also produced excellent images on plain papers by printing in a multiple pass printing mode (heat and checkerboarding method). Very good color gamut and hue are also demonstrated. The physical properties and jetting performance of the ink jet inks (Examples IA, IB, and IC) are shown in Table I. As demonstrated, these color ink jet inks have a low viscosity, low surface tension, good drop mass, good drop volume and low jitters (very small percentage of deviation of transit time from the mean value). The recoverability (maximum allowable idling time of an ink that can still be jetted by a printhead to produce a detectable drop of ink after 9 drops of jetting (9 pulses)) of the cyan, magenta, and yellow inks in this Example (Example I) is good. All three inks (Examples IA, IB, and IC) were jetted with a 600 spi printhead (i.e., a LYK-075 printhead) and jetting experiments were carried out to at least 1 x 10 8 drops without observing any undesired degradation of their jetting performance (transit time or drop velocity, frequency response, latency, and the like). Excellent long-term jetting stability of these inks is demonstrated without any undesired kogation. Example II A set of color ink jet inks including magenta, yellow and cyan inks were prepared with the following compositions using the same procedure as Example I. Example IIA : A magenta ink jet ink was prepared comprising 25.0% Project Magenta Dye Concentrate (10% dye solution.), 6.0% Acid Red 52 (10% dye solution), 0.5% Lomar D, 4.0% Butylcarbitol, 2 0% N-cyclohexylpyrrolidinone, 4.0% polyethyleneglycol (Ave. MW=200), 5.0% triethanolamine, 7.0% N-acetylethanolamine (N-2-hydroxyethylacetamide), 0.1% Igepal CA-630, 2.0% NH 4 Br, 0.05% Dowicil 200, 0.05% Polyethyleneoxide (MW = 18,500), and 44.3% Distilled Water. The pH of this ink is 7.01 and the ink conductivity is 23,000 umhos/cm. Example IIB : A yellow ink jet ink was prepared comprising 25.2% Project Yellow Dye Concentrate (7.5% dye solution.), 17.0% Acid Yellow 17 Dye Concentrate (10% dye solution), 9.32% Butylcarbitol, 1.86% N-, 4.9% 1-(2-hydroxyethyl)-2-pyrrolidinone, 13 98% Sulfolane, 1.9% NH 4 Br, 0 047% Dowicil 200, 0.047% Polyethyleneoxide (MW = 18,500), and 23.71% Distilled Water. The pH of this ink was 7.08 and the conductivity is 16,900 umhos/cm. Example IIC : A cyan ink jet ink was prepared comprising 34.8% Project Cyan Dye Concentrate (10% dye solution), 0 45% Lomar D, 4 0% Butylcarbitol, 2.0% N-cyclohexylpyrrolidinone, 9.0% glycerol, 8.0% N-acetylethanolamine (2-hydroxyethyl acetamide), Igepal CA-630, 0.05% Dowicil 200, 0.05% Polyethyleneoxide (MW = 18,500), and 41.35% Distilled Water The pH of this ink is 7.02 and the ink conductivity is 3,500 umhos/cm. The physical properties and jetting performance of these ink jet inks (Examples IIA, IIB, and IIC) are shown in Table I. Latency, jetting frequency, and other performance results were similarly obtained as in Example I. As demonstrated, the color ink jet inks also have a low viscosity, low surface tension, high drop mass or high drop volume, low jitters, and good recoverability. Example III A set of color ink jet inks was prepared including magenta, yellow, and cyan inks with the following compositions using the same preparation procedure as Example I. Their physical properties and jetting data are shown in Table I. Example IIIA : A magenta ink jet ink was prepared comprising 25.0%. Project Magenta Dye (10% dye Sol.), 6.0% Acid Red 52 (10% dye Sol.), 12.0% Butylcarbitol, 15.0% Sulfolane, 13.0% N-acetylethanolamine(N-2-hydroxyethylacetamide), 0.05% Dowicil 200, 3.0% NH 4 Br, 0.05% Polyethyleneoxide (MW = 18,500), and 25.9% Distilled Water. The pH of this ink is 7.01 and the ink conductivity is 16,000 umhos/cm. Example IIIB : A yellow ink jet ink is prepared comprising 27.0% Project Yellow Dye (7.5% dye Sol.), 20.0% Acid Yellow 17 (10% dye Sol.), 12.0% Butylcarbitol, 15.0% Sulfolane, 13.0% N-acetylethanolamine(N-2-hydroxyethylacetamide), 3.0% NH 4 Br, 0.05% Dowicil 200, 0.05% Polyethyleneoxide (MW = 18,500), and 9.9% Distilled Water. The pH of this ink is 7 01 and the ink conductivity is 16,500 umhos/cm. Example IIIC: A cyan ink jet ink was prepared comprising 35.0% Project Cyan Dye (10% Sol.), 12.0% Butylcarbitol, 10.0% Sulfolane, 16.0% N-acetylethanolamine(N-2-hydroxyethylacetamide), 3.0% NH 4 Br, 0.05% Dowicil 200, 0.05% Polyethyleneoxide (MW = 18,500), and 23.9% Distilled Water. The pH of this ink is 7.01 and the ink conductivity is 15,000 umhos/cm. The physical properties and jetting performance of the ink jet inks are shown in Table I. Latency, jetting frequency, and other performance results were obtained similarly as in Example I. As demonstrated, the color ink jet compositions also have a low viscosity, low surface tension, good drop mass (good drop volume), and low jitters The recoverability is good. All three inks (Examples IIIA, IIIB, and IIIC) were jetted with a 600 spi printhead and jetting experiments were carned out to at least 1 x 10 8 drops without observing any undesired degradation of their jetting performance (transit time or drop velocity, frequency response, latency). Excellent long-term jetting stability of these inks was demonstrated without any undesired kogation. The inks (Examples IIIA, IIIB, and IIIC) were printed on a series of plain papers with full-width array printheads and heated with a microwave dryer (device). The ink jet printing of ink Examples IIIA, IIIB, and IIIC was carried out on a set of plain papers using a single pass method at a speed of greater than 18 pages per minute. The set (NT) of plain papers included 3NT (Recycled Bond paper, Domtar, Cornwall-Ontaro), 7NT (Xerox Image Series LX), 10NT (Hammermill Tidal DP, International Paper Selma, Al.), 11NT (Xerox 4024 DP), 12NT (Rank Xerox, Premier ECF), 13NT (Ran Xerox Premier TCF), 14NT (Champion, Brazil), 15NT (Rank Xerox Business, Aussedat-Rey), 16NT (Rank Xerox Exclusive), 17NT (Rank Xerox Priemer TCF, Nymolla), 18NT (Xerox 4024), 19NT (Cascade Xerographic paper), 20NT (Spectrum DP), 21NT (Husky Xerocopy), 22NT (Xerox Image Elite), and 23NT (Fuji Xerox Paper) The average paper temperature was about 55-60°C after they were printed and exited from the microwave dryer. No smearing of the images was observed. The inks in this Example III comprising the NH 4 Br salt and other ingredients which couple very well with the microwave dryer (heater). Excellent color images were obtained on the plain papers with low intercolor bleeding. The physical properties and jetting data of the cyan, magenta, and yellow inks (Examples I, II, and III, a total of 9 inks) are listed in Table I. The thermal ink jet printhead used for jetting these inks at 35°C has a resolution of 600 spi and a nozzle size less than 25 micrometers. The relative humidity near the printhead nozzles was maintained at 15% during the jetting measurements. Physical Properties and Jetting Data of Ink Examples I, II, and III INK mPa.s (cps) Y 10 5 N/cm (dynes/ cm) Printhead Drop Mass (ngm) Drop Vel. (m/s) f max (kHz) Jitter 1st Drop Latency (sec) 9th Drop Latency, Recov. (9 drops) (sec) Example I Magenta(IA) 3.17 40.0 LYK-075 15.0 15 4 6 0.5 50-75 100 Yellow(IB) 3 27 40.0 LYK-075 14.6 15 6 0.3 40 75 Cyan(IC) 3.19 39.5 LYK-075 14.3 14 1 6 0.4 50-75 200 Example II Magenta(II) 2.3 36 0 LYK-075 16 0 4 30 30-50 Yellow(IIB) 2.3 40.5 LYK-075 16.3 5 200 500 Cyan(IIC) 2.3 35.5 LYK-075 14 5 6 40 100-200 Example III Magenta(IIIA) 3.3 39.0 LYK-075 15.0 15.1 6 0 4 50-75 200 Yellow(IIIB) 3 32 40.0 LYK-075 14 6 14.8 6 0.3 40-50 100 Cyan(IIIC) 3.3 38.5 LYK-075 14.6 14.4 6 0.4 50-75 100 Example IV A set of ink jet inks including Example IVA (magenta ink), Example IVB (yellow ink), and Example IVC (cyan ink)) were prepared using the corresponding formulations and procedures of Example III (Example IIIA, IIIB and IIIC), except for omitting the ammonium bromide salt and replacing it with additional water. All three color inks have a surface tension less than 4.5x10 -4 N/cm (45 dynes/cm) A black ink (Example IVD) was also prepared comprising 17% BASF X-34 Black dye (30% dye solution), 3% Direct Red 227 (10% dye solution, Na salt), 6% trimethylolpropane, 20% sulfolane, 0.05% polyethyleneoxide (MW = 18,500), 0.05% Dowicil 200, 1.25% ammonium formate, and water (balance). The surface tension of the black ink is 5 3x10 -4 N/cm (53 dynes/cm). Examples IVA, IVB and IVC were printed on a series of plain papers by full-width array printheads and heated with a microwave dryer. The ink jet printing of ink Examples IVA, IVB, and IVC was carried out on the NT set of plain papers using a single pass method at a speed of greater than 18 pages per minute. The average paper temperature was about 45-55 °C after they were printed and exited from the microwave dryer. No smearing of the images was observed. The color inks IVA, IVB and IVC couple very well with the microwave dryer without the NH 4 Br salt. Excellent color images were obtained on the plain papers with low intercolor bleeding. Inks (IVA, IVB, IVC, and IVD) were also printed on several print substrates (e.g., plain papers). The black ink (IVD) was printed with a full-width array printhead (600 spi) onto a plain paper first followed by drying with a microwave dryer. The print substrate comprising the black images was subsequently printed with the color inks IVC, IVA, and IVB by their corresponding full-width array printheads (600 spi) in a printing sequence of cyan, magenta, and yellow. Very good full color images were obtained on plain papers without smearing at a speed of 11 cm (4.33 inches) per second (about 18 pages per minute). Very low black/color and color/color intercolor bleeding were observed on many papers including Xerox Image Series LX paper when the black ink (IVD) was printed next to the yellow ink (IVB). Table II shows the intercolor bleeding data of Midrange Frequency Line Edge Noise (MFLEN), which is a method of evaluating print quality of a line. A low MFLEN number indicates good image quality with low intercolor bleeding of the image near the border of the black ink (IVD) and the yellow ink (IVB). A high MIFLEN number indicates poor image quality with undesired inter color bleeding. An intercolor bleeding MFLEN value of less than 20 is generally acceptable. Intercolor Bleeding Data of Inks (IVD) and (IVB). Paper Type (See Example III For Detailed Description) MFLEN Data 3NT 26 7NT 1.8 11NT 138 13NT 44 14NT 6.1 15NT 3.4 Example V A pigment ink comprising 5% carbon black Raven 5250 (an AMES negative pigment), 1.125% sodium naphthalene sulfonate salt (Lomar D), 10% sulfolane, 10% N-acetylethanolamine, 0.05% Dowicil 200, and water (balance) was prepared The pH of this ink was adjusted to neutral, centrifuged, and filtered through a series of membrane filters 5.0µm/3.0µm/1.2µm. The ink was printed on a paper using either a 600 spi printhead or a 300 spi pnnthead. Example VI. Comparative Example A A black ink comprising 17.3% BASF X-34 dye concentrate (about 30% dye solution), 20% ethyleneglycol, 0.075% polyethyleneoxide (MW = 18,500), 0 1% Dowicil, and water (balance) was prepared. The black ink was adjusted to pH 7.0 and filtered through a series of membrane filters 5.0µm/1 2/µm/0.8µm. The ink was tested under the same conditions as those inks described in Examples I, II, and III. The ink had only 5 sec latency with poor performance when it was used with a 600 spi printhead. The result clearly shows the advantage of ink Examples I, II, and III of this invention (see Table I). Example VII: Comparative Example B Another black ink comprising 11.0% BASF X-34 dye concentrate (about 30% dye solution), 20% ethyleneglycol, 0.075% polyethyleneoxide (MW = 18,500). 0.1% Dowicil, and water (balance) was prepared. The black ink was adjusted to pH 7.0 and filtered through a series of membrane filters 5.0µm/1.2/µm/0.8µm. The ink was tested under the same conditions as those inks described in Examples I, II, and III. The ink had only 10 sec latency with poor jetting performance when it was used with a 600 spi printhead. The result clearly shows the advantage of ink Examples I, II, and III of this invention (see Table I).

Claims: An aqueous ink jet ink composition comprising a colorant, a hydroxyamide derivative which has at least two hydroxyl groups and at least one amide group or a reaction product of oxyalkylene and said hydroxyamide derivative, and a sulfur-containing humectant selected from the group consisting of sulfoxide, sulfone, and thiol derivatives, wherein said hydroxyamide derivative is represented by the following formula: wherein R is independently selected from the group consisting of H, C n H 2n+1 , cyclic C n H 2n-1 , C 6 H 5 , C 5 H 4 N, OC n K 2n+1 , and substituted or unsubstituted aromatic groups as well as heterocyclic groups with carbon atoms from three to twenty wherein n is from one to forty; characters J and X are independently selected from H and C k H 2k+1 and k is from zero to twenty; Q and P are independently selected from two to twenty; U and W are independently selected from one to twenty; Y and Z are independently selected from zero to forty where Y+Z must be one or greater than one; V and E are independently selected from zero to forty where V+E must be one or greater than one; and P, Q, U, W, V, Z, E, Y, X, and J are independently selected. An ink jet ink composition according to claim 1, wherein said hydroxyamide derivative is selected from the group consisting of N,N'-Bis(2-hydroxyethyl)oxamide and isomers thereof. An ink jet ink composition according to any of claims 1 to 2, wherein the said oxyalkylene includes ethyleneoxide, propyleneoxide, and mixtures thereof. The ink jet ink composition according to claim 1, wherein [(C Q H 2Q ) U - O] v ] and (C p H 2p ) w - O] z is independently substituted by a C 6 H 4 O- group or an alkylphenoxy group. An ink jet ink composition according to any of claims 1 to 4, wherein the said sulfur-containing humectant is selected from the group consisting of sulfoxide derivatives including alkylphenyl sulfoxide derivatives and dialkylsulfoxide derivatives; sulfone derivatives including sulfolane, methylsulfolane, ethylsulfolane, propylsulfolane, butylsulfolane, dimethylsulfolane, methyl ethyl sulfolane; sulfone derivatives including alkylsulfone derivatives, dialkyl sulfone derivatives, and alkyl phenyl sulfone derivatives; thiol derivatives including alkylthiol derivatives, phenylthiol derivatives, and thioglycol derivatives; and mixtures thereof. An ink jet ink composition according to any of claims 1 to 5, further comprising a humectant selected from the group consisting of various glycol derivatives, 1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, glycerine, trimethylolpropane, 1,3,5-triols, 1,2,5-triols, 2-pyrrolidinone, N,N-dimethylforamide, N-methylacetamide, N,N-dimethylacetamide, caprolactam, urea, betaine, alcohols including methanol, ethanol, isopropanol, n-propanol, n- butanol, n-petanol, n-hexanol, amino alcohol derivatives, reaction products of above hydroxyl compounds and alkyleneoxide derivatives, their isomers, and mixtures thereof. A thermal ink jet printing process comprises: incorporating into a thermal ink jet printer at least one ink jet ink according to any of claims 1 to 6; printing with at least one ink jet printhead selected from the group consisting of a single printhead, a partial-width printhead, and a full-width array printhead in an imagewise pattern according to digital signals onto a print substrate; and optionally heating said print substrate by a heating means at any stage of printing process including before, during, after, and combinations thereof.

Inventors: LIN JOHN WEI-PING, LIN, JOHN WEI-PING
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1998
Main classification: C09D11
IPC codes: B41M5, C09D11