Background of the Invention As ink jet technology has improved, ink jet printing is being used for increasingly critical imaging applications, such as proofing, high end graphics, etc.

One key factor in controlling image quality is the receptor. Desirably the receptor enables the ink image to dry rapidly. Slow drying may lead to smearing of the undried image.

Another issue that becomes critical in certain applications is the image stability (also referred to as"dye fade") over time. Dye fade can lead to unacceptable image quality if it is severe or if it occurs over relatively short time periods.

A receptor for ink jet printing typically comprises a support material bearing an ink receiving material. A variety of compound and mixtures have been propose for use as the ink receiving material. For example, U. S. Patent No.

3,889,270 describes an ink-receiving layer consisting of a protein, polysaccharide, cellulose, a cellulose derivative, polyvinyl alcool, a copolymer of vinyl alcool, gelatin, albumen, casein or silica gel. One problem with gelatin receiving layers is that such layers do not yield good ink jet printed images, particularly in portions having relatively large areas of high density inks. This appears to be due to the relatively slow rate of water absorbency from the inks. This allows pudding to occur when inks are applied because a substantial amount of aqueous liquid must be absorbe by the receptor layer.

Gelatin has been blended with other water absorptive polymers to improve the absorption rate into the coating (i. e. dry time). For example, U. S. Patent

No. 5,141,599 discloses a receptor layer which contains a mixture of gelatin and starch. U. S. Patent No. 4,503,111 teaches the use of polyvinylpyrrolidone (PVP) blended with a compatible matrix-forming polymer (swellable by water and insoluble at room temperature but soluble at elevated temperatures). The matrix forming-polymer described inclues gelatin or polyvinyl alcohol (PVA).

Applicants have found that such blends have poor image stability.

Other patents, such as U. S. Patent Nos. 5,389,723 and 5,342,688, describe a composition that is capable of forming liquid-absorbent, semi-interpenetrating networks, hereinafter referred to as SIPNs. The SIPNs disclosed are polymeric blends wherein at least one of the polymeric components is crosslinked after blending to form a continuous network throughout the bulk of the material, and through which the uncrosslinked polymeric component or components are intertwined in such a way as to form a macroscopically homogenous composition.

Applicants have found that these systems show acceptable dry times but their image stability is not as good as a gelatin receiving layer.

Use of two layer receiving materials has also been discussed. US 5,567,507 and WO 96/26840 disclose an ink-receptive coating comprising at least two layers, a base layer for ink absorption, and a thin upper layer comprising methylcellulose, hydroxypropyl cellulose or blends of those materials. This coating shows a fast dry time, but Applicants have found it to have poor image stability. Additional publications (JP 63039373, JP 62263084, JP 61035988) discuss the use of at least two coating layers for inkjet media where the ink absorption rate of the top receiving layer is higher than the ink absorption of the lower receiving layer.

Applicants have found that such systems appear to have poor image stability.

U. S. Patent 4,877,678 teaches an ink jet receptor having a first water absorbing layer which has a thickness of 3 to 30 gm and a second water-absorption controlling layer which has a thickness of 5 to 50 tm. The second layer comprises a water absorptive inorganic filler in a polymeric binder. The binder may be gelatin.

JP 60259488 discloses an ink jet recording element in which surface tack is adjusted by (i) fixing powder on the surface, (ii) applying a coating of starch, gelatin, polyamide, melamine resin, PVA, etc. over the surface or (iii) using select materials in the ink acceptance layer. JP 2055186 discloses a system having an ink holding layer and an ink penetration layer. The ink penetration layer is 5-150 llm thick and contains porous particles in a binder selected ftom PVA acrylic resins, PVP, starch, methylcellulose, gelatin, etc. JP 1262183 discloses a system having an ink accepting layer and a protecting layer which is cured with an anti-diffusive crosslinking agent. The binder for the protective layer may be gelatin, starch, methyl cellulose, or water-soluble synthetic polymer.

Summary of the Invention Applicants have discovered that a receptor having a very thin layer of gelatin over a layer of a water absorptive material provides excellent dye stability without substantial deterioration in dry time for water based inks. Specifically, this invention is an ink receiving element comprising a substrate, a first layer of a first ink receiving material on the substrat, and a second layer of a second ink receiving material over the first layer, the second ink receiving material comprising gelatin.

According to one embodiment the second layer consists essentially of gelatin, preferably consisting only of gelatin.

According to a second embodiment, the second layer may include other materials such as matting agents and the second layer is coated at a dry coating weight of less than 0.65 g/ft2.

According to yet another embodiment, the second layer may include other materials such as matting agents and the second layer has a thickness of less than 5 pm.

According to yet another embodiment, the invention is a method of forming an image on the above described receptors by use of an ink jet apparats. While the receptor of this invention is primarily concerne with performance with aqueous based inks, it is also contemplated that the receptor may be used with solvent based inks.

Detailed Description of the Invention The substrate may be any material that provides a suitably strong support for the ink receiving layers. Examples of suitable substrats include paper, cloth, polymers, metals, and glass. Thin flexible sheets are preferred. Paper is useful when an opaque support is desired, while polymeric films may provide translucent or transparent supports. The thickness of the substrate is preferably in the range of 0.05 to 1.0 mm. The substrate may be treated with a subbing laver such as a primer or an antistatic layer. An anti-curl layer may be coated on the back side of the substrat.

The first ink receiving material may be any water absorptive ink receiving material known in the art. Hydrophilic polymers which absorb water at room temperature in an amount of preferably at least 1.0, more preferably at least 1.5, times the weight of the polymer are preferred. Non-limiting examples of suitable materials include polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyhydroxyethylmethacrylate, cellulose, cellulose derivatives, polymers containing acrylic acid, and semi-interpenetrating polymeric networks as disclosed in US 5,389,723; US 5,342,688; WO 96/26840; and WO 96/26841. The first layer preferably has a thickness of about 5 to about 75 pm.

The second ink receiving material comprises as a major component gelatin.

Gelatin is a derived protein which, though not homogeneous, is chemically well defined. It is the main product of mild, but irreversible collagenolytic breakdown.

When tissues which contain collagen are subjected to mildly degradative processes, usually involving treatment with alkali or acid followed or accompanied by some degree of heating in the presence of water, the systematic fibrous structure of the collagen is broken down irreversibly. The main product of this change has

characteristic properties. It forms a highly viscous solution in water, which sets to a gel on cooling and its chemical composition is, in many respects, closely similar to that of its parent collage. Thus, gelatin is a protein and, in common with all proteins, is made up of amino acids joined together by peptide linkages to form polymer chains. The nature of the side chain group will vary for différent amino acids. Gelatin is compose of 18 different amino acids and its composition is remarkably consistent, irrespective of its physical properties or whether it is derived from hide/skin or bone collagen or manufactured by an acid or alkali process. Certain features of the amino acid composition which are characteristic of gelatin and its parent protein collagen are the high glycine content (approximately one third of the total number of residues), the high hydroxyproline content; the presence of hydroylysine, and the deficiency of sulphur-containing amino acids and tryptophan. The term gelatin is applied not only to the"protein"but also to the commercial product which contains, not only the protein as its main constituent but also smaller amounts of various inorganic and organic impurities. Commercially available sources of gelatin include Photographic Gelatin 17332 (referred to herein as Gel), 17907 (G2), and 19720 (G5) from Systems Bio Industries, Inc. Langhorne, PA ; Photographic Gelatin P-4117 (G3) from Nitta Gelatin Inc. Osaka, Japan; Hydrolized Gelatin D4572 (G4), Tilapia Fish Skin Gelatin (OCL REF 96411) (G6), Low Viscosity Deionised Gelatin (G7) and Gelatin Bone 669 Photographic (G8) from Croda Colloids Ltd. Cheshire, England.

Applicants have found that even very thin layers of gelatin improve dye fade resistance. However, the second layer should not be so thick as to have a long dry time. Preferably, the thickness is less than 5 Lm, more preferably, less than 4 , um. Due to the coating process the interface between the first and second layers may be graduated rather than a sharp interface. Therefore, it is also helpful to define the thickness by coating weight of the second layer. Preferably, the coating weight is less than 0.65 g/* (lg/ft2 = 10.8 g/m'-), more preferably less than 0.55 gel*.

Additives such as surfactants, plasticizers, antistatic agents, buffers, coating aids, matting agents, particulates for managing mechanical processing of the ink

receiving element, hardeners, colorants, viscosity modifiers, preservatives, and the like may also be added to either or both the first and second layers. The gelatin layer could be lightly crosslinked by several methods known in the art. One way would be to use a cross-linking agent (e. g. formaldehyde) incorporated in the coating composition used to form the ink-receiving layer. The ink-receiving layer would be non-blocking yet would have to rapidly absorb the water-based liquid ink that is applied thereto. The gelatin layer must not harden to too high a degree, or the ink-receiving layer will not rapidly absorb the ink and may cause the ink to pool at the surface.

These receptors fonction well as receptors for ink jet printing or image forcing. Any suitable in jet printer or the like mat bye used. Suitable examples of such printers include Iris Realist 5030 (Iris Graphics), HP Deskjet 855C (Hewlett Packard), and Epson Stylus Pro (Epson America).

EXAMPLES In the following experiments, dye stability and dry time (absorption rate into the coating) are measured for a series of different materials. Dye stability measurements are discussed within each sample set. All density measurements were done by a Gretag spectrophotometer (either Gretag SMP 50 LT or Gretag Spectroscan and Spectrolino). dE = hE*ab = square root of [ (AL*) 2+ (ha*) 2 + (Ab*) 2] where AL*, Aa*, and Ab* represent the change in L*, a*, and b* between the original and aged amples. hE*ab = the CIE [Commission Internationale de l'Eclairage (International Commission of Illumination)] 1976 (L*a*b*) color difference or CIELAB color difference where a 3D model is used whereby L is the lightness axis, a is the red-green axis, and b is the yellow-blue axis. Image stability was determined for light fade using a fluorescent fade box at 1500 ft-cd in a controlled enviromnent (21°C and 50% RH) for 48 or 72 hours or for dark fade, 24 hours in the dark at ambient conditions.

Dry times were evaluated using the following procedure. A 0.5 cm wide and 23.6 cm long magenta stripe with an optical density (OD) of 2.08 was printed

on the coating. The printer used is the HP Deskjet 855C (Hewlett-Packard, Palo Alto, CA) which takes approximately 3 minutes to print this stripe. After waiting some designated amount of time, a Xerographic copier paper (Cascade X-9000, Boise Cascade Paper Division) is placed on the stripe and a metal roller of parameters: 6.4cm wide, 10. 1cm diameter and 4.2kg weight is rolled over the copier paper once in a single direction. The copier paper is then removed from the coated paper and the density of the magenta color on the copier paper is measured at a specified place. By taking into account the time off the printer before applying the paper as well as where the measurement on the paper is taken, one can determine the length of time it takes for the ink to be absorbe into the coating.

All experimental coatings were done over a polyethylene coated paper base.

The specific gelatins used are identifie as Gl-G8 having the identities listed as above. In all cases when gelatin was used, the gelatin was placed in deionized water for 30 minutes at ambient conditions and then heated at 50°C for at least one hour. Triton X-100, a surfactant (available from Rohm and Haas) was then added and the solution was coated warm (at around 40°C). If gelatin was being blended with another polymer, the gelatin was placed in deionized water for 30 minutes at ambient conditions and then heated at 50°C for at least one hour. The other polymer was dissolve in deionized water and then added to the 50°C gelatin solution. Then the TritonTM X-100 was added and the entire solution was coated at around 40°C. Coating weights were determined by the Meyer rod number, wet thickness, % solids of solutions and material density (1.36 for gelatin) or by empirically weighing the coating.

Example 1 In this series of experiments, polyvinylpyrolidone, manufactured by ISP Technologies and sold under the tradename PVP-K90 (PVP) and gelatin (G1), were used.

In Comparative Sample &num 1C, a coating solution of 10% PVP in deionized water containing TritonTM X-100 at a level of 2 drops for every gram of PVP was

coated using a knife coater (at 5 mil (127 pm) gap) and dried at 60°C for 5 minutes.

In Comparative Sample #2C, a coating solution containing 10% GI in deionized water and Triton X-100 at a level of 2 drops for every gram of G1 was coated using a knife coater (5 mil (127 pm) gap) and dried at 60°C for 7 minutes.

Comparative Sample #3C was a 10% coating solution of solids containing one part (by weight) of PVP and one part G1 in deionized water. TritonTM X-100 was used at a level of 2 drops for every gram of solid. This solution was coated using a knife coater (5 mil (127 pm) gap) and dried at 60°C for 5 minutes.

Comparative Sample #4C was initially prepared the same as Comparative Sample #2C except with the addition of formaldehyde (0.34 grams per 10 grams of gelatin). A hardener was necessary or the G 1 could not be overcoated (the over coat layer solvent attacked the gelatin underlayer). Then, the coated surface was overcoated with a 10% solution of PVP in deionized water with Triton X-100 at a level of 2 drops for every gram of PVP using a 22 Meyer rod and dried for 5 minutes at 60°C.

In Sample &num 1, PVP was coated as stated in Comparative Sample &num 1C.

Then, the coated surface was overcoated with a 10% solution of G1 in deionized water with Triton X-100 at a level of 2 drops for every gram of gelatin using a 18 Meyer bar, dried for 60°C for 6minutes In this Example, Iris Realist 5030 (Iris Graphics, Bedford, MA) printer and inks were used to image. Image stability was determined using a fluorescent fade box at 1500 ft-cd (1 ft-cd = 1 foot candle corresponds to a flux density of 1 Lumen/square foot = a flux density of 27.3 Lumens/square meter) in a controlled environment (21 °C and 50% relative humidity) for 48 hours. The average dE refers to an averaging of primary and secondary colors as well as black and 3 color black for 6 steps of color throughout the density range from 5% to 100% coverage.

Duplicates of each formulation were included in the averaging of dE. The maximum dE refers to the average of the highest dE observe for any color, any step for each replicate.

The gelatin alone layer shows good image stability while the PVP alone layer shows poor image stability. When incorporating PVP into the GI layer at 50 weight %, a small improvement in image stability is observe relative to the PVP alone coating; however, the image stability is still poor when compare to the G1 alone layer. When overcoating G1 with PVP, dye stability is as poor as the PVP alone layer. When overcoating PVP with G1, dye stability improved to almost that of the G1 alone.

Dry times show that PVP is substantially faster at absorbing the ink than G1. And, that blending or overcoating the G1 layer with PVP improves the dry time significantly when compare to the gelatin only layer. Overcoating PVP with gelatin gave a slower dry time than PVP alone.

Example 2 In this series of experiments, the standards shown are X, a two layer construction having a substrat, a first layer with a coating weight of 2.04g/ sq. ft., and a second layer with a coating weight of. 08g/ sq. ft. and Y, a one layer construction having substrate and layer with a coating weight of 1.3g/ sq. ft. These coating weights were determined empirically by weighing the coatings. For X, the substrate is polyethylene coated paper of 185 microns with a very thin subbing layer of gelatin to promote adhesion. For X, the bottom layer solution was made following example 2 in patent WO 96/26840 with the following changes: Pycal 94 used at 17 g per 100g polymer and the coating solution was made with 75% water and 25% ethanol (160 roof). The top layer solution was made following example 9 in WO 96/26841 with the following specifics: 1.2 g of Methocel K15M, 2.1g of Ludox LS, 0.7g of PEI (water free)/PTSA (1: 2.2), 0.13g of 8p polymethylmethacrylate beads, 0. 05g of Zonyl (Dupont), 76.4g of water, and 19.6g of 160 proof ethanol. The coating method used was extrusion. For Y, the substrate was a polyethylene coated paper base of 147 microns with a very thin subbing layer of gelatin to promote adhesion. Solution was made following example 1 in patent US 5,342,688 with the following exceptions: level changes of copolymer B at 55% solids, VinylTm 523 at 30% solids and GohsenolTm at 10% solids ;

polyethylene glycol 600 (Aldrich Chem. Co., Inc.) added at 3% solids; no polymethylmethacrylate beads were added. The coating method used was extrusion.

Comparative Sample &num 1C was X. Comparative Sample #2C was Y. In comparative sample #3C, the X bottom layer was coated. In comparative samples #4C-#6C, coating solutions (10% in deionized water) containing Y solution as described above and Gl at the described weight percent ratios were made. TritonTM X-100 was added at a level of 2 drops per gram of solid. These solutions were coated on a knife coater at a 5 mil (127 pLm) gap and dried at 60°C for 5 minutes.

In comparative sample #7C, a 10% solution of G1 with TritonTM X-100 (added at a <BR> <BR> <BR> <BR> level of 2 drops per gram of solid) in deionized water was knife coated at a D mil (127 pm) gap and dried at 60°C for 8 minutes.

For samples &num 1 and #2, coatings of comparative sample #2C and comparative sample #3C were overcoated with G1 at 10% solids in deionized water with Triton X-100 (2 drops per gram G1) using a 16 Meyer bar and dried at 60°C for 6 minutes.

Iris Realist 5030 (Iris Graphics, Bedford, MA) printer and inks were used.

Image stability was determined using a fluorescent fade box at 1500 ft-cd (1 ft-cd = 1 foot candle corresponds to a flux density of 1 Lumen/square foot = a flux density of 27. 3 Lumens/square meter) in a controlled environment (21°C and 50% relative humidity) for 48 hours. The average dE refers to an averaging of primary and secondary colors as well as black and 3 color black for 4 steps of color throughout the density range from 25% to 100% coverage. Duplicates of each formulation were included in the averaging of dE. The maximum dE refers to the average of the highest dE observe for any color, any step for each replicate.

When incorporating G1 into the Y layer, some improvement in the dye stability was observe when compare to the Y layer alone. However, the dry time of the Y layer was degraded by incorporating G1. By overcoating the Y or X layer, a large improvement was seen in dye stability. In the case of example 2, sample #2

(G1 overcoating), the dye stability was increased to nearly that of the G1 alone layer. The dry times were improved with the G1 overcoatings.

Example 3 In example 3, comparative sample #1C, Y coating was made as described in Example 2, comparative sample 2C. In example 3, sample 1, comparative sample lc was then overcoated with Gl as described in example 2, samplel except using a 10 Meyer bar.

Iris Realist 5030 (Iris Graphics, Bedford, MA) printer and inks were used.

Image stability for dark fade was determined by measuring the ink densities within the first hour after printing, placing the samples in the dark at ambient conditions and, after 24 hours, measuring the densities again. The average dE refers to an averaging of primary and secondary colors as well as black and 3 color black for 4 steps of color throughout the density range from 25% to 100% coverage.

Duplicates of each formulation were included in the averaging of dE. The maximum dE refers to the average of the highest dE observe for any color, any step for each replicate.

When overcoating gelatin over the original Y receptor, dE values (both average and maximum) were greatly decreased, showing a vast improvement in image stability. The dry times were improved with the G1 overcoatings.

Example 4 In this experiment, comparative samples &num 1C, &num 2C, &num 3C are used that were described in example 2, comparative samples #1C, #3C, #2C, respectively.

Sample #1 was prepared as described in example 2, ample &num 2. Samples &num 2-&num 4 were prepared as described in example 2, sample #1. The only difference being that gelatin was coated with a 18 Meyer rod and different gelatins (as described in Table 1) were used for samples #3 and #4.

HP Deskjet 855C (Hewlett-Packard, Palo Alto, CA) printer and inks were used. Image stability was determined using a fluorescent fade box at 1500 ft-cd in a controlled environment (21°C and 50% relative humidity) for 72 hours. The

average dE refers to an averaging of primary and secondary colors as well as black and 3 color black for 4 steps of color with densities ranging from mid-tones to highest density. Duplicates of each formulation were included in the averaging of dE. The maximum dE refers to the average of the highest dE observe for any color, any step for each replicate.

When gelatin was used as an overcoat for the X (bottom layer) or Y formulations, an increase in dye stability was demonstrated. For the HP inks, the gelatin overcoat greatly decreased the dE values (both average and maximum).

The magnitude of the dye stability effect was independent of the type of gelatin used.

Exam, ple 5: In this experiment, comparative samples &num 1C and #2C are used that were described in example 2, comparative samples &num 1 C and &num 3C, respectively. In comparative sample &num 3C, a coating solution of 10% solids of polyvinyl alcohol (PVA) manufactured by Air Product and Chemicals and sold under the tradename Airvol 523 in deionized water was coated using a knife coater (at 5 mil (127 Lm) gap) and dried at 60°C for 5 minutes. In comparative sample 4C, a coating solution of 10% solids of polyvinyl alcohol (PVA) sold as GohsenolTM (from Nippon Gohsei) was coated over Y using a 22 Meyer bar and dried at 60°C for 5 minutes.

Samples #1-#5 used were described in example 2, sample #2. The only difference being that gelatin was coated with a 18 Meyer rod and different gelatins as described above were used. Epson Stylus Pro (Epson America, Torrance, CA) printer and inks were used. Image stability was determined using a fluorescent fade box at 1500 ft-cd in a controlled environment (21 °C and 50% relative humidity) for 72 hours. The average dE refers to an averaging of primary and secondary colors as well as black and 3 color black for 4 steps of color with densities ranging from mid-tones to highest density. Duplicates of each formulation were included in the averaging of dE. The maximum dE refers to the average of the highest dE observe for any color, any step for each replicate.

The sample using PVA showed poor dye stability and a slow dry time. When gelatin was used as an overcoat for the X (bottom layer) formulation, an increase in dye stability was demonstrated. For the Epson inks, the gelatin overcoat greatly decreased the dE values (both average and maximum). In the Epson inks, certain types of gelatin had somewhat differing results in the magnitude of the reduction in both the average and maximum dE values. The magnitude of the dye stability effect is somewhat dependent on the ink and gelatin type.

Table 1 Examples Sample Material Dye Dye Dry Dry time stabilitytime#stability Ave dE Max dE OD of (time in min. at magent which little or no a@4 color is observe minutes (OD of magenta at that time)) 1 (IRIS(IRIS1C PVP 7.1 29.80.117 6min (0.099) inks) 2C Gelatin I (G 1) 1.2 4.0 1. 357 33min (0.96*) 3C PVP/G1 (50%/50%) 5.9 24.1 0.096 10min (0.08) (Incorporate gelatin into PVP) 4C PVP at 0.65g/sq. ft. 6.9 28.7 0.106 8min (0.08) (Overcoat gelatin with PVP) 1 G1 at 0.53g/sq. ft. 1. 7 5.9 0.134 8min (. 124) (Overcoat PVP with gelatin) (IRIS 1C X 7. 1 22.6 0.083 4.0min (0.083) inks) 2C y 4.4 11.7 0.13 10min (0.09) 3C X (bottom layer) 8 25.8 0.131 9min (0.075) 4C Y/GI (80%/20%) 3.6 12.2 0.271 13min (0.107) (Incorporate gelatin intoY) SC Y/G I (65%/35%) 3.3 13.1 0.39 13min (0.099) (Incorporate gelatin intoY) 6C Y/GI (50%/50%) 2.6 8.8 0.711 13min (0.096) (Incorporate gelatin into Y) 7C G1 1. 2 4 1.357 33min (0.96*) 1 Y with 0.47g/sq. ft. 2.1 7.1 0.135 6min (. 082) G I overcoat 2 X (bottom layer 1.9 5.2 0.097 4min (. 072) only); with 0.47g/sq. ft. G I overcoat 3 (Iris 1C Y 1. 5 8.5 0.13 10min (. 09) Fadé) Fades 1 Y with 0.30g/sq. ft. 0.3 0. 9 0.133 6min (. 093) OC (GI) 4 (HP inks) 9.439.7X 2C X (bottom layer) 7.3 15.7 3C Y 4.2 13.7 1 X (bottom layer); 3.8 7.7 0.47g/sq. ft. OC (Gl) 2 (Y as bottom layer; 2.7 5.9 with 0.53 g/sq. ft. G Iovercoat) 3 (Y as bottom layer; 2.6 6.0 with 0.53 g/sq. ft. G7 overcoat) 4 (Y as bottom layer; 2.7 6.1 with 0.53 g/sq. ft. G8 overcoat) (Epson I C X 9.7 35 inks) 2C X (bottom layer) 4.3 11.5 3C PVA 7.1 33.9 0.17 13min (. 150) 4C Y with 0.65 g/sq ft 4.9 32.2 0.124 7 min (0.084) of PVA overcoat I (X (bottom layer); 3.5 9.1 with 0.53g/sq. ft. G2 overcoat) 2 (X (bottom layer); 3.4 9.4 with 0.53g/sq. ft. G3 overcoat) 3 (X (bottom layer); 3.2 7.8 with 0.53g/sq. ft. G4overcoat) 4 (X (bottom layer); 2.8 6.6 with 0.53g/sq. ft. G5overcoat) 5 (X (bottom layer); 2.7 7.2 with 0.53g/sq. ft. G6 overcoat) * Significant magenta color is still observe.

Example 6: In this experiment, G1 was coated at different coating weights over the Y formulation (which was coated as described in Example 2, sample #2C). For samples gl-&num 3, GI was overcoated using an extrusion method and coating weight was measured. For sample #4-#6, G1 was overcoated as described in Example 2, sample 41 with the difference being the Meyer rod number (22,30 and 36 respectively).

Iris Realist 5030 (Iris Graphics, Bedford, MA) printer and inks were used.

Image stability was determined using a fluorescent fade box at 1500 ft-cd in a controlled environment (21°C and 50% relative humidity) for 48 hours. The average dE refers to an averaging of primary and secondary colors as well as black and 3 color black for 4 steps of color throughout the density range from 25% to 100% coverage. Duplicates of each formulation were included in the averaging of dE. The maximum dE refers to the average of the highest dE observe for any color, any step for each replicate.

In this series of experiments, it is shown that the dye stability improves and then levels off as the gelatin overcoat coating weight is increased (Table 2).

Table 2-Dye Stability with varying thickness of gelatin (Iris inks) Example6 Sample # Material Ave dE Max dE 1 Y with 0.14g/sq. ft. OC of 3.2 8.1 Go 2 Y with 0.28g/sq. ft. OC of 2.7 6.3 Gui 3 Y with 0.42g/sq. ft. OC of 2.6 5.8 GI 4 Y withO. 65g/sq. ft. OC of 1.7 4.3 Gui 5 Y with 0.88g/sq. ft. OC of 1.3 3.6 GI 6 Y with 1.05g/sq. ft. OC of I. 1 3.5 GI

Example 7: In this experiment, GI was coated over Y formulation as described in Example 2, sample #1. The only difference was the Meyer rod number: sample #1, 10; sample #2,16; sample &num 3, 30; and in sample #4, a knife coater was used at a 5 mil (127 pm) gap. For sample #4, coating weight was measured.

This expriment shows that slower dry times are recorde as the coating weight of the gelatin overcoat is increased (Table 3).

Table 3-Dry times with varying thicknesses of gelatin Example 7 Sample # Material Dry time Dry time OD of magenta time in min. at which (0 little or no color is 4min observe (OD of magenta at that time) 1 Y with 0.30g/sq.ft. OC 0.133 6min (. 093) of GI with0.47g/sq.ft.OC0.1356min(.082)2Y ofIl with3Y 0.1418min(0.121)OC ofGo with1.68g/sq.ft.OC0.16513min(0.121)4Y ofGI