Recording sheets and ink jet printing processes therewith

Abstract: Disclosed is a recording sheet which comprises a substrate and an image-receiving layer situated on at least one surface of the substrate, said image-receiving layer being suitable for receiving images of an aqueous ink, said image-receiving layer comprising (a) a binder polymer; and (b) an additive selected from the group consisting of (5-carboxy-4-hexyl-2-cyclohexen-1-yl) octanoic acid, (6-carboxy-4-hexyl-2-cyclohexen-1-yl) octanoic acid, saccharin salts, dihexyl sulfosuccinate salts, benzoate salts, monohydroxy-substituted benzoate salts, dihydroxy-substituted benzoate salts, trihydroxy-substituted benzoate salts, benzene sulfonate salts, monohydroxy-substituted benzene sulfonate salts, dihydroxy-substituted benzene sulfonate salts, benzene disulfonate salts, toluene sulfonate salts, bromobenzene sulfonate salts, xylene sulfonate salts, cumene sulfonate salts, cymene sulfonate salts, cinnamate salts, isonicotinate salts, gallate salts, piccolinate salts, hydroxynaphthoate salts, n-butylmonoglycolsulfate salts, 2-ethylhexylsulfate salts, p-aminobenzoic acid acid salts, procaine acid salts, dibucaine acid salts, caffeine, resorcinol, and mixtures thereof.

Description: The present invention is directed to recording sheets particularly suitable for ink jet printing processes. More specifically, the present invention is directed to recording sheets and to ink jet printing processes employing said sheets wherein the sheets enable the generation of high quality images and exhibit reduced or no haze in the image receiving layer thereof. JP-A-8-239622 discloses a recording sheet for ink jet printing comprising a substrate and an image-receiving coating thereon, said coating containing a binder polymer and sodium p-toluenesulfonate. JP-A-7-251562 discloses a recording sheet comprising a substrate and an image-receiving coating thereon, said coating containing sodium benzoate in an amount of 1 percent by weight based on the weight of the coating composition. JP-A-6-270529 discloses an ink jet recording sheet comprising a support, an image-receiving layer and a pigment layer, said pigment layer containing di-2-ethyl hexyl sodium sulfosuccinate. JP-A-60-230895 discloses a transfer type heat-sensitive recording material containing caffeine. While known compositions and processes are suitable for their intended purposes, a need remains for improved recording sheets. In addition, a need remains for recording sheets which are suitable for receiving images of aqueous inks, such as those commonly employed in ink jet printing. Further, a need remains for transparent recording sheets which are suitable for receiving images of aqueous inks and which also exhibit reduced or no haze. Additionally, a need remains for transparent recording sheets which are suitable for receiving images of aqueous inks, which exhibit reduced or no haze, and which enable the generation of high quality images thereon. There is also a need for opaque recording sheets wherein the image receiving coatings thereon exhibit little or no haze, thereby enabling high quality and clarity of color in images generated thereon. It is an object of the present invention to provide recording sheets with the above noted advantages. These and other objects of the present invention are achieved by providing a recording sheet according to claim 1 or claim 8. The present invention further provides a printing process according to claim 15. Preferred embodiments of the present invention are set forth in the sub-claims. The present invention is directed to a recording sheet comprising a substrate and an image-receiving layer. The substrate can be either transparent or opaque. Any suitable transparent substrate can be employed. Examples include transparent materials, such as polyester. The substrate can also be opaque, including opaque plastics and filled polymers. Paper is also suitable, including plain papers such as Xerox@ 4024, or diazo papers. The substrate can be of any effective thickness. Typical thicknesses for the substrate are from 50 to 500 µm, and preferably from 100 to 125 µm, although the thickness can be outside these ranges. The image-receiving layer comprises a binder polymer and an additive as defined in the claims. Examples of suitable binder polymers include hydrophilic polysaccharides and their modifications, such as (1) starch, (2) cationic starch, (3) hydroxyalkylstarch, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, and more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl (such as hydroxypropyl starch and hydroxyethyl starch), (4) gelatin, (5) alkyl celluloses, aryl celluloses and benzyl cellulose, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, and even more preferably from 1 to 7 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, or hexyl (such as methyl cellulose), and wherein aryl has at least 6 carbon atoms and wherein the number of carbon atoms is such that the material is water soluble, preferably from 6 to 20 carbon atoms, more preferably from 6 to 10 carbon atoms, and even more preferably about 6 carbon atoms, such as phenyl cellulose, (6) hydroxy alkyl celluloses and hydroxy benzyl cellulose, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, or hexyl (such as hydroxyethyl cellulose and hydroxypropyl cellulose), (7) alkyl hydroxy alkyl celluloses, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, or hexyl (such as ethyl hydroxyethyl cellulose), (8) hydroxy alkyl alkyl celluloses, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl (such as hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose and hydroxy butylmethyl cellulose), (9) dihydroxyalkyl cellulose, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl (such as dihydroxypropyl cellulose, which can be prepared by the reaction of 3-chloro-1,2-propane with alkali cellulose), (10) hydroxy alkyl hydroxy alkyl cellulose, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl (such as hydroxypropyl hydroxyethyl cellulose), (11) halodeoxycellulose, wherein halo represents a halogen atom (such as chlorodeoxycellulose, which can be prepared by the reaction of cellulose with sulfuryl chloride in pyridine at 25°C), (12) amino deoxycellulose (which can be prepared by the reaction of chlorodeoxy cellulose with 19 percent alcoholic solution of ammonia for 6 hours at 160°C), (13) dialkylammonium halide hydroxy alkyl cellulose, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl, and wherein halide represents a halogen atom (such as diethylammonium chloride hydroxy ethyl cellulose), (14) hydroxyalkyl trialkyl ammonium halide hydroxyalkyl cellulose, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl, and wherein halide represents a halogen atom (such as hydroxypropyl trimethyl ammonium chloride hydroxyethyl cellulose), (15) dialkyl amino alkyl cellulose, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl (such as diethyl amino ethyl cellulose), (16) carboxyalkyl dextrans, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, or hexyl (such as carboxymethyl dextrans), (17) dialkyl aminoalkyl dextran, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl (such as diethyl aminoethyl dextran), (18) amino dextran, (19) carboxy alkyl cellulose salts, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl, and wherein the cation is any conventional cation, such as sodium, lithium, potassium, calcium, or magnesium (such as sodium carboxymethyl cellulose), (20) gum arabic, (21) carrageenan, (22) karaya gum, (23) xanthan, (24) chitosan, (25) carboxyalkyl hydroxyalkyl guar, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl (such as carboxymethyl hydroxypropyl guar), (26) cationic guar, (27) n-carboxyalkyl chitin, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl, such as n-carboxymethyl chitin, (28) dialkyl ammonium hydrolyzed collagen protein, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl (such as dimethyl ammonium hydrolyzed collagen protein), (29) agar-agar, (30) cellulose sulfate salts, wherein the cation is any conventional cation, such as sodium, lithium, potassium, calcium, or magnesium (such as sodium cellulose sulfate), and (31) carboxyalkylhydroxyalkyl cellulose salts, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, or butyl, and wherein the cation is any conventional cation, such as sodium, lithium, potassium, calcium, or magnesium (such as sodium carboxymethylhydroxyethyl cellulose). Also suitable are polymers which form latices in water and which are applied to the substrate in the form of a latex, including styrene-butadiene latexes (such as that available from Gen Corp Polymer Products, such as RES 4040 and RES 4100, available from Unocal Chemicals, and such as DL 6672A, DL6638A, and DL6663A, available from Dow Chemical Company), ethylene-vinyl acetate latexes (such as Airflex 400, available from Air Products and Chemicals Inc.), vinyl acetate-acrylic copolymer latexes (such as synthemul 97-726, available from Reichhold Chemical Inc., Resyn 25-1110 and Resyn 25-1140, available from National Starch Company, and RES 3103 available from Unocal Chemicals), quatemary acrylic copolymer latexes, including those of the formula wherein n is a number of from 10 to 100, and preferably about 50, R is hydrogen or methyl, R 1 is hydrogen, an alkyl group, or an aryl group, and R 2 is (N + (CH 3 ) 3 ) n X n- , wherein X is an anion, such as Cl - , Br - , I - , HSO 3 - , SO 3 2- , CH 2 SO 3 - , H 2 PO 4 - , HPO 4 2- , or PO 4 3- , n is an integer of from 1 to 3, and the degree of quaternization is from 1 to 100 percent, including polymers such as polymethyl acrylate trimethyl ammonium chloride latex, including HX42-1 and HX42-3, available from Interpolymer Corp. Also suitable are polyethylene oxides and polyethylene oxide derivatives, such as (1) poly(oxyethylene) or poly(ethylene oxide); (2) ethylene oxide/2-hydroxyethyl methacrylate/ethylene oxide and ethylene oxide/hydroxypropyl methacrylate/ethylene oxide triblock copolymers, which can be synthesized via free radical polymerization of hydroxyethyl methacrylate or hydroxypropyl methacrylate with 2-aminoethanethiol using α,α'-azobisisobutyronitrile as initiator, and reacting the resulting amino-semitelechelic oligo-hydroxyethyl methacrylate or amino-hydroxypropyl methacrylate with an isocyanate-polyethylene oxide complex in chlorobenzene at 0°C, and precipitating the reaction mixture in diethylether, filtering and drying in vacuum; (3) ethylene oxide/4-vinyl pyridine/ethylene oxide triblock copolymers, which can be synthesized via anionic polymerization of 4-vinyl pyridine with sodium naphthalene as initiator at -78°C and then adding ethylene oxide monomer, the reaction being carried out in an explosion proof stainless steel reactor; (4) ionene/ethylene oxide/ionene triblock copolymers, which can be synthesized via quatemization reaction of one end of each 3-3 ionene with the halogenated, preferably brominated, poly(oxyethylene) in methanol at about 40°C; (5) ethylene oxide/isoprene/ethylene oxide triblock copolymers, which can be synthesized via anionic polymerization of isoprene with sodium naphthalene in tetrahydrofuran as solvent at -78°C, and then adding monomer ethylene oxide and polymerizing the reaction for three days, after which time the reaction is quenched with methanol, the ethylene oxide content in the aforementioned triblock copolymers being from 20 to 70 percent by weight and preferably about 50 percent by weight; and (6) ethylene oxide/propylene oxide copolymers, including ethylene oxide/propylene oxide/ethylene oxide triblock copolymers, propylene oxide/ethylene oxide/propylene oxide triblock copolymers, tetrafunctional block copolymers derived from the sequential addition of ethylene oxide and propylene oxide to ethylene diamine, the content of ethylene oxide in these block copolymers being from 5 to 95 percent by weight, such as Tetronic 50R8 available from BASF Corporation. Mixtures of any two or more of the above binder polymers can also be employed. Suitable additives include (5-carboxy-4-hexyl-2-cyclohexen-1-yl) octanoic acid, (6-carboxy-4-hexyl-2-cyclohexen-1-yl) octanoic acid, saccharin salts, such as sodium saccharin, dihexyl sulfosuccinate salts, such as sodium dihexyl sulfosuccinate, benzoate salts, such as sodium benzoate, wherein the ratio of binder polymer to benzoate salt is as defined in claim 8, monohydroxy-substituted benzoate salts, of the general formula wherein X is a cation, including salicylate salts such as sodium salicylate, dihydroxy-substituted benzoate salts, of the general formula wherein X is a cation, trihydroxy-substituted benzoate salts, of the general formula wherein X is a cation, benzene sulfonate salts, such as sodium benzene sulfonate, monohydroxy-substituted benzene sulfonate salts, of the general formula wherein X is a cation, dihydroxy-substituted benzene sulfonate salts, of the general formula wherein X is a cation, benzene disulfonate salts, such as sodium benzene disulfonate, bromobenzene sulfonate salts, such as sodium p-bromobenzene sulfonate, xylene sulfonate salts, such as sodium xylene sulfonate, cumene sulfonate salts, such as sodium cumene sulfonate, cymene sulfonate salts, such as sodium cymene sulfonate, cinnamate salts, such as sodium cinnamate, isonicotinate salts, such as sodium isonicotinate, gallate salts, such as sodium gallate, piccolinate salts, such as sodium 4-piccolinate, hydroxynaphthoate salts, such as sodium 3-hydroxy-2-naphthoate, n-butylmonoglycolsulfate salts, such as sodium n-butylmonoglycolsulfate, 2-ethylhexylsulfate salts, such as sodium 2-ethylhexylsulfate, p-aminobenzoic acid acid salts, such as p-aminobenzoic acid hydrochloride, procaine acid salts, such as procaine hydrochloride, caffeine, as well as mixtures thereof. Examples of suitable salts of the above materials also include, for example, potassium salts, lithium salts, or ammonium salts. Examples of suitable acid salts of the above materials also include, for example, acetic acid salts, lactic acid salts, glycolic acid salts, or nitric acid salts. Recording sheets with gallate salts or caffeine are outside the scope of claim 1. The binder and the additive are present in relative amounts with respect to each other so as to enable reduction or elimination of haze in the image receiving layer. When the substrate is transparent, haze is thus reduced or eliminated in the entire transparency. Haze is measured as the percentage of light which is prevented from passing through the transparent recording sheet. For example, if a transparency allows 97 percent of the light shining upon it to pass through, the transparency has a haze value of 3. Haze can be measured by any desired or suitable apparatus, such as a XL-211 HAZEGARD hazemeter, available from Pacific Scientific Co. Transparent recording sheets of the present invention typically have haze values of no more than 10, preferably no more than 3, and more preferably no more than 2, although the haze value can be outside this range. Typically, the binder and the additive are present in relative amounts with respect to each other of from 5 percent by weight additive and 95 percent by weight binder to 33 percent by weight additive and 67 percent by weight binder. Preferably the additive is present in an amount of at least 10 percent by weight of the binder/additive mixture. The coating containing the binder and additive is present on the substrate of the recording sheet of the present invention in any effective thickness. Typically, the total thickness of the coating layer (on each surface, when both sides of the substrate are coated) is from 1 to 25 µm and preferably from 5 to 10 µm, although the thickness can be outside of these ranges. If desired, additional layers can be present in the recording sheet, such as layers situated between the substrate and the image-receiving layer, protective overcoatings situated so that the image-receiving layer is between the substrate and the overcoating, antistatic layers, or anticurl layers. The coating or coatings can be applied to the substrate by any suitable technique. For example, the layer coatings can be applied by a number of known techniques, such as size press treatment, dip coating, reverse roll coating, or extrusion coating. For example, the coating can be applied with a KRK size press (Kumagai Riki Kogyo Co., Ltd., Nerima, Tokyo, Japan) by dip coating and can be applied by solvent extrusion on a Faustel Coater. Recording sheets of the present invention can be employed in ink jet printing processes. One embodiment of the present invention is directed to a process which comprises applying an aqueous recording liquid to a recording sheet of the present invention in an imagewise pattern. Another embodiment of the present invention is directed to a printing process which comprises (1) incorporating into an ink jet printing apparatus containing an aqueous ink a recording sheet of the present invention, and (2) causing droplets of the ink to be ejected in an imagewise pattern onto the recording sheet, thereby generating images on the recording sheet. Ink jet printing processes are well known, and are described in, for example, US-A-4,601,777, US-A-4,251,824, US-A-4,410,899, US-A-4,412,224, and US-A-4,532,530. 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. The recording sheets of the present invention can also be used in any other printing or imaging process, such as printing with pen plotters, handwriting with ink pens, or offset printing processes, provided that the ink employed to form the image is compatible with the ink receiving layer of the recording sheet. Specific embodiments of the invention will now be described in detail. All parts and percentages in the examples are by weight unless otherwise indicated. EXAMPLE I Transparency sheets are prepared as follows. Blends of 70 percent by weight hydroxypropyl methyl cellulose (HPMC) K35LV (Dow Chemical) and 30 percent by weight of various additive compositions are prepared by mixing 56 grams of hydroxypropyl methyl cellulose and 24 grams of the additive composition in 1,000 milliliters of water in a 2 Liter jar and stirring the contents in an Omni homogenizer for 2 hours. Subsequently, the solution is left overnight for removal of air bubbles. The blends thus prepared are then coated by a dip coating process (both sides coated in one operation) by providing Mylar® base sheets in cut sheet form (21.59x27.94 cm (8.5×11 inches)) in a thickness of 100 µm. Subsequent to air drying at 25°C for 3 hours followed by oven drying at 100°C for 10 minutes and monitoring the difference in weight prior to and subsequent to coating, the dried coated sheets are each coated with 1 gram, 10 µm in thickness, on each surface (2 grams total coating weight for 2-sided transparency) of the substrate. Additive compositions employed are as follows: The transparency sheets thus prepared were incorporated into a Hewlett-Packard 500-C color ink jet printer containing inks of the following compositions: Cyan: 20 percent by weight ethylene glycol, 2.5 percent by weight benzyl alcohol, 1.9 percent by weight ammonium chloride, 0.1 percent by weight Dowicil 150 biocide, 0.05 percent by weight polyethylene oxide (molecular weight 18,500), 30 percent by weight Projet Cyan 1 dye, 45.45 percent by weight water. Magenta: 20 percent by weight ethylene glycol, 2.5 percent by weight benzyl alcohol, 1.9 percent by weight ammonium chloride, 0.1 percent by weight Dowicil 150 biocide, 0.05 percent by weight polyethylene oxide (molecular weight 18,500), 2.5 percent by weight Triton Direct Red 227 dye, 72.95 percent by weight water. Yellow: 20 percent by weight ethylene glycol, 2.5 percent by weight benzyl alcohol, 1.9 percent by weight ammonium chloride, 0.1 percent by weight Dowicil 150 biocide, 0.05 percent by weight polyethylene oxide (molecular weight 18,500), 3 percent by weight Hoechst Duasyn Brilliant Yellow SF-GL VP220 dye, 72.45 percent by weight water. Images are generated by printing block patterns for magenta, cyan, yellow, and black. The black images are "process black" (i.e., formed by superimposition of cyan, magenta, and yellow images). It is believed that the images thus formed will exhibit good color, optical density, dry times, and edge characteristics. It is also believed that the transparencies, both before and after imaging, will exhibit good haze values of no more than 10, and, in most instances, of no more than 3. The above process is repeated with the exception that the coating composition contains 5 percent by weight additive and 95 percent by weight additive. It is believed that similar results will be obtained. The above process is repeated with the exception that the coating composition contains 10 percent by weight additive and 90 percent by weight additive. It is believed that similar results will be obtained. The above process is repeated with the exception that the coating composition contains 20 percent by weight additive and 80 percent by weight additive. It is believed that similar results will be obtained. EXAMPLE II The process described in Example I is repeated with the exception that the binder polymer is sodium carboxymethyl cellulose (CMC 7HOF, Hercules Chemicals). It is believed that similar results will be obtained. EXAMPLE III The process described in Example I is repeated with the exception that the binder polymer is a mixture of hydroxypropyl methyl cellulose (HPMC) K35LV (Dow Chemical) (75 percent by weight) and polyethylene oxide (POLY OX WSRN-3000, Union Carbide) (25 percent by weight). It is believed that similar results will be obtained. EXAMPLE IV The process described in Example I is repeated with the exception that the binder polymer is a mixture of sodium carboxymethyl cellulose (CMC 7HOF, Hercules Chemicals) (60 percent by weight) and polyethylene oxide (POLY OX WSRN-3000, Union Carbide) (40 percent by weight). It is believed that similar results will be obtained. EXAMPLE V The process described in Example I is repeated with the exception that the binder polymer is a mixture of hydroxypropyl methyl cellulose (HPMC) K35LV (Dow Chemical) (50 percent by weight), sodium carboxymethyl cellulose (CMC 7HOF, Hercules Chemicals) (25 percent by weight) and polyethylene oxide (POLY OX WSRN-3000, Union Carbide) (25 percent by weight). It is believed that similar results will be obtained. EXAMPLE VI The processes described in Examples I through V are repeated with the exception that the substrate is Xerox 10 Series Smooth paper and that the image receiving layer is applied with a #7 Mayer rod, resulting in a coating about 11 µm thick. It is believed that the images thus formed will exhibit good color, optical density, dry times, and edge characteristics.

Claims: A recording sheet which comprises a substrate and an image-receiving coating situated on at least one surface of the substrate, said image-receiving coating being suitable for receiving images of an aqueous ink, said image-receiving coating comprising (a) a binder polymer and (b) an additive selected from the group consisting of (5-carboxy-4-hexyl-2-cyclohexen-1-yl) octanoic acid, (6-carboxy-4-hexyl-2-cyclohexen-1-yl) octanoic acid, saccharin salts, dihexyl sulfosuccinate salts, monohydroxy-substituted benzoate salts, dihydroxy-substituted benzoate salts, trihydroxy-substituted benzoate salts, benzene sulfonate salts, monohydroxy-substituted benzene sulfonate salts, dihydroxy-substituted benzene sulfonate salts, benzene disulfonate salts, bromobenzene sulfonate salts, xylene sulfonate salts, cumene sulfonate salts, cymene sulfonate salts, cinnamate salts, isonicotinate salts, piccolinate salts, hydroxynaphthoate salts, n-butylmonoglycolsulfate salts, 2-ethylhexylsulfate salts, p-aminobenzoic acid acid salts, procaine acid salts, and mixtures thereof. The recording sheet of claim 1 wherein the substrate is opaque. The recording sheet of claim 1 wherein the substrate is transparent. The recording sheet of claim 3 wherein said recording sheet has a haze value of no more than 10, preferably no more than 3 and most preferably no more than 2. The recording sheet of any of claims 1 to 4 wherein the binder polymer and the additive are present in the image-receiving coating in relative amounts with respect to each other of from 5 percent by weight additive and 95 percent by weight binder polymer to 33 percent by weight additive and 67 percent by weight binder polymer. The recording sheet of any of claims 1 to 5 wherein the image-receiving coating contains the additive in an amount of at least 10 percent by weight and contains the binder polymer in an amount of no more than 90 percent by weight. The recording sheet of any of claims 1 to 6 wherein the additive is selected from the group consisting of sodium saccharin, sodium dihexyl sulfosuccinate, sodium salicylate, sodium benzene sulfonate, sodium benzene disulfonate, sodium p-bromobenzene sulfonate, sodium xylene sulfonate, sodium cumene sulfonate, sodium cymene sulfonate, sodium cinnamate, sodium isonicotinate, sodium 4-piccolinate, sodium 3-hydroxy-2-naphthoate, sodium n-butylmonoglycolsulfate, sodium 2-ethylhexylsulfate, p-aminobenzoic acid hydrochloride, procaine hydrochloride, and mixtures thereof. A recording sheet which comprises a substrate and an image-receiving coating situated on at least one surface of the substrate, said image-receiving coating being suitable for receiving images of an aqueous ink, said image-receiving coating comprising (a) a binder polymer and (b) a benzoate salt, wherein the binder polymer and the benzoate salt are present in the image-receiving coating in relative amounts with respect to each other of from 5 percent by weight benzoate salt and 95 percent by weight binder polymer to 33 percent by weight benzoate salt and 67 percent by weight binder polymer. The recording sheet of claim 8 wherein the image-receiving coating contains the benzoate salt in an amount of at least 10 percent by weight and contains the binder polymer in an amount of no more than 90 percent by weight. The recording sheet of claim 8 or 9 wherein said benzoate salt is sodium benzoate. The recording sheet of any of claims 8 to 10 wherein the substrate is opaque. The recording sheet of any of claims 8 to 10 wherein the substrate is transparent. The recording sheet of claim 12 wherein said recording sheet has a haze value of no more than 10, preferably no more than 3 and most preferably no more than 2. The recording sheet of any of claims 1 to 13 wherein the binder polymer is selected from the group consisting of starch; cationic starch; hydroxyalkylstarch, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms in alkyl is such that the material is water soluble; gelatin; alkyl celluloses, wherein alkyl has at least 1 carbon atom and wherein the number of carbon atoms in alkyl is such that the material is water soluble; aryl celluloses, wherein aryl has at least 6 carbon atoms and wherein the number of carbon atoms in aryl is such that the material is water soluble; hydroxy alkyl celluloses, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms in alkyl is such that the material is water soluble; alkyl hydroxy alkyl celluloses, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms in each alkyl is such that the material is water soluble; hydroxy alkyl alkyl celluloses, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms in each alkyl is such that the material is water soluble; dihydroxyalkyl cellulose, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms in alkyl is such that the material is water soluble; hydroxy alkyl hydroxy alkyl cellulose, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms in each alkyl is such that the material is water soluble; halodeoxycellulose, wherein halo represents a halogen atom; amino deoxycellulose; dialkylammonium halide hydroxy alkyl cellulose, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms in alkyl is such that the material is water soluble, and wherein halide represents a halogen atom; hydroxyalkyl trialkyl ammonium halide hydroxyalkyl cellulose, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms in each alkyl is such that the material is water soluble, and wherein halide represents a halogen atom; dialkyl amino alkyl cellulose, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms in each alkyl is such that the material is water soluble; carboxyalkyl dextrans, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms in alkyl is such that the material is water soluble; dialkyl aminoalkyl dextran, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms in each alkyl is such that the material is water soluble; amino dextran; carboxy alkyl cellulose salts, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms in alkyl is such that the material is water soluble; gum arabic; carrageenan; karaya gum; xanthan; chitosan; carboxyalkyl hydroxyalkyl guar, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms in each alkyl is such that the material is water soluble; cationic guar; n-carboxyalkyl chitin, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms in alkyl is such that the material is water soluble; dialkyl ammonium hydrolyzed collagen protein, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms in each alkyl is such that the material is water soluble; agar-agar; cellulose sulfate salts; carboxyalkylhydroxyalkyl cellulose salts, wherein each alkyl has at least one carbon atom and wherein the number of carbon atoms in each alkyl is such that the material is water soluble; styrene-butadiene latexes; ethylene-vinyl acetate latexes; vinyl acetate-acrylic copolymer latexes; quaternary acrylic copolymer latexes; poly(ethylene oxide); ethylene oxide/2-hydroxyethyl methacrylate/ethylene oxide triblock copolymers; ethylene oxide/hydroxypropyl methacrylate/ethylene oxide triblock copolymers; ethylene oxide/4-vinyl pyridine/ethylene oxide triblock copolymers; ionene/ethylene oxide/ionene triblock copolymers; ethylene oxide/isoprene/ethylene oxide triblock copolymers; ethylene oxide/propylene oxide copolymers; and mixtures thereof. A process which comprises applying an aqueous recording liquid in an imagewise pattern to a recording sheet which comprises a substrate and an image-receiving coating situated on at least one surface of the substrate, said image-receiving coating comprising (a) a binder polymer and (b) an additive selected from the group consisting of (5-carboxy-4-hexyl-2-cyclohexen-1-yl) octanoic acid, (6-carboxy-4-hexyl-2-cyclohexen-1-yl) octanoic acid, saccharin salts, dihexyl sulfosuccinate salts, monohydroxy-substituted benzoate salts, dihydroxy-substituted benzoate salts, trihydroxy-substituted benzoate salts, benzene sulfonate salts, monohydroxy-substituted benzene sulfonate salts, dihydroxy-substituted benzene sulfonate salts, benzene disulfonate salts, bromobenzene sulfonate salts, xylene sulfonate salts, cumene sulfonate salts, cymene sulfonate salts, cinnamate salts, isonicotinate salts, gallate salts, piccolinate salts, hydroxynaphthoate salts, n-butylmonoglycolsulfate salts, 2-ethylhexylsulfate salts, p-aminobenzoic acid acid salts, procaine acid salts, caffeine, and mixtures thereof, said image receiving coating being suitable for receiving images of an aqueous ink. A printing process which comprises (1) incorporating into an ink jet printing apparatus containing an aqueous ink a recording sheet as defined in claim 15, and (2) causing droplets of the ink to be ejected in an imagewise pattern onto the recording sheet, thereby generating images on the recording sheet.

Inventors: SCHWARZ WILLIAM M JR, SCHWARZ, WILLIAM M., JR.
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1998
Main classification: B41M5
IPC codes: B41M5, B42D15