PHOTOSENSITIVE ELEMENTS

Abstract: Photosensitive elements particularly suitable for use in diffusion transfer photographic film units which include a plurality of essential layers including at least one photosensitive silver halide layer having associated therewith a dye image-forming material which is diffusible during processing as a function of the point-to-point degree of silver halide exposure to actinic radiation and a layer adapted to receive image-forming material diffusing thereto and means for applying an aqueous processing composition. The silver halide layer comprises gelatin and inert particles which are compatible with gelatin, non-swelling in alkali and substantially non-film forming, wherein said inert particles are equal to or less than the silver halide grains in average diameter and wherein the silver halide grains are 2.5 microns or less in average diameter. Preferably, the inert particles are derived from a polymeric latex. In a particularly preferred embodiment, the photosensitive silver halide layer comprises a first and second photosensitive silver halide layer in contiguous relationship.

Description: PHOTOSENSITIVE ELEMENTS ' BACKGROUND OF THE INVENTION Diffusion transfer photographic products and pro¬ cesses are known to the art and details relating thereto can be found in U. S. Patents Nos. 2,983,606; 3,415,644; 3,415,645; 3,415;646; 3,473,925; 3,482,972; 3,551,406; 3,573,042; 3,573,043; 3,573,044; 3,576,625; 3,576,626; 3,578,540; 3,569,333; 3,579,333; 3,594,164; 3,594,165; 3,597,200; 3,647,437; 3,672,486; 3,672,890; 3,705,184 3,752,836; 3,857,865; all of which are incorporated here their entirety. Essentially, diffusion transfer photographic products and processes involve film units having a photo- sensitive system including at least one silver halide layer, usually integrated with an image-providing material. After photoexposure, the photosensitive system is developed to establish an imagewise distribution of a diffusible image- providing material, at least a portion of which is trans- ferred by diffusion to an image-receiving layer capable of mordanting or otherwise fixing the transferred image-pro¬ viding material. In some diffusion transfer products the transfer image is viewed by reflection after separation of the image-receiving element from the photosensitive system. In other products, however, such separation is not required and instead the transfer image-receiving layer is viewed against a reflecting background usually provided by a dispersion of a white reflecting pigment, such as, for example, titanium dioxide. The latter type of film unit is generally referred to in the art as integral negative-positive film units and are described, for example, in the above-mentioned U. S. Patents Nos. 3,415,644 and 3,594,165. It is known in the art to incorporate polymeric latices into gelatin silver halide emulsion layers to increase the flexibility of the silver halide layer, thus eliminating the occurrence of fog due to stresses set up in the film unit containing the aforementioned silver halide layer. U. S. Patent No. 2,772,166 discloses gelatin silver halide emulsions which also contain a hydrosol resulting from the emulsion polymerization of a mixture ^ styrene, acrylonitrile or a vinylidene chloride with an alkyl acrylate or alkyl ethacrylate and acrylic acid. The described hydrosol is used in the range of 1 to 10% of the gelatin. U. S. Patent No. 2,835,582 is directed to mix¬ tures of gelatin and polymeric hydrosols in silver halide layers wherein the hydrosol is prepared by polymerizing at least .one monoethylenically unsaturated monomer in the presence of an ampholytic surface active agent. Among th suitable monomeric materials are mentioned methylmeth- acrylate and styrene. It is a requirement that the poly¬ meric materials be film formers and the essence of the invention resides in the presence of the ampholytic sur¬ face active material to provide its enhanced compatibilit with gelatin. U. S. Patent No. 3,157,510 is directed to gelat silver halide emulsions which also include a dispersion o minute particles of a water insoluble soft acrylate polym resin at a level of about 5 to 40% by weight of gelatin. U. S. Patent No. 3,325,286 is directed to gelat silver halide emulsions which include an aqueous dispersi of a polymeric vinyl compound and .at least one anionic dispersing agent specified in the patent. The emulsion layer also requires a polyoxyethylene' compound as defined in the patent. One of the polymeric materials recited is a homopolymer of an α-hydrocarbon substituted acrylic aci ester. U. S. Patent No. 3,547,650 is directed to gelat silver halide emulsions which include an aqueous dispersi of a polymeric vinyl compound dispersed with a mixture of specified organic phosphates. One of the polymerized vin compounds recited comprises a homopolymer of an α-hydrocarbon substituted acrylic acid ester. U. S. Patent No. 3,772,032 is directed to a gelatin silver halide emulsion which includes a polymeric latex prepared by emulsion polymerization in the presence of at least 5% by weight of an emulsifying agent to reduc the stress sensitivity of the emulsion. This patent stat Λ, that employing the specified emulsifying agent at a level of at least 5% by weight,, no fog is found in emulsions employing large amounts of methyl ethacrylate in the latex whereas normally the presence of even 50% of methylmethacrylate in the latex results in intolerable increases in fog. ϋ. S. Patent No. 3,773,517 is directed to gelatin- silver halide emulsion which include a polymer latex pre¬ pared by copolymerization of a monomer yielding a water insoluble homopolymer and a monomer yielding a water soluble polymer. The patent requires the polymerization to occur in the presence of a specified alkylaryl polyether phosphate surface active agent. One of the monomers which would produce a water insoluble homopolymer is an alk lmethacrylate. U. S. Patent No. 3,418,132 is directed to a photo¬ graphic film unit which, in one embodiment, is particularly suited for rapid access processing by virtue of the incorporation of inert particles into at least one layer of the photographic element. The inert particles include starch, barium sulfate, calcium carbonate, synthetic resins etc. The inert particles are in the range of 7 to 15 microns ' . Film units containing contiguous silver halide emulsion layers sensitive to the same spectral region are known to the art as shown by the following representative patents. U. S. Patent No. 3,505,068 is directed to a photographic element which contains overlying silver halide emulsions wherein the first emulsion is a regular silver haloiodide emulsion and the second contains grains which have an iodide-free shell and a silver iodide core. U. S. Patent No. 3,663,228 is directed to a photographic film unit having a plurality of silver halide emulsion layers divided into sets with each set of a different speed while the layers in each set have the same speed but are responsive to different spectral regions. Color filters are disposed between the layers. U. S. Patent No. 3,695,882, is directed to a photosensitive element comprising a support carrying two emulsions, each containing a non-diffusing color coupler. Each emulsion lias a different speed and different silver halide-coupler molar ratio. U. S. Patent No. 3,846,135 is directed to a synergistic increase in the sensitivity of two superposed silver halide layers when the lower layer is less sensiti than the upper layer and has a maximum density of at lea 1.5 compared to .a maximum density of at least 0.9 for the upper layer. The lower layer is about 5 to 15U thick. U. S. Patents Nos. 3,960,558 and 4,003,744 dis¬ close diffusion transfer film units which employ split silver halide emulsions having dye image-forming material associated therewith and which, in fact, contain dye image-forming material in one of said contiguous layers. U. S. Patent No. 3,632,342 is directed to a photographic element comprising a support carrying at lea one layer containing a high contrast silver halide emulsi layer containing an acrylic latex material and an additio silver halide layer containing a hydrophilic colloid whic is free of latex micelles. It is stated that discrete micelles are preferred but that coalescing may occur. Copolymers of hydrophilic and hydrophobic monomers are disclosed. A, SUMMARY OF THE INVENTION The photographic film unit of the present inven¬ tion comprises at least a first photosensitive silver halide emulsion layer having associated therewith a dye image-forming material, preferably a dye developer which is soluble and diffusible in alkali as a function of the exposure and development of the silver halide emulsion layer, and a polymeric layer dyeable by said dye image- providing material wherein said dyeable polymeric layer is at least in superposed relationship with said photo¬ sensitive element after exposure of said element and during processing of the exposed photosensitive silver halide emulsion, that is, during contact of said emulsion with the aqueous alkaline processing composition; and wherein said photosensitive silver halide emulsion layer comprises photosensitive silver halide grains disposed in a mixture of gelatin and inert particles which are substantially non- swelling in alkali, compatible with gelatin, and substan¬ tially non-film forming or non-coalescing; which particles are equal to or less than the silver halide grains in average diameter and wherein the silver halide grains are 2.5 microns or less in diameter. Preferably the film units of the present inven¬ tion are integral negative-positive film units of the types described, for example, in U. S. Patents Nos. 3,415,644 and 3,647,437, which patents are incorporated herein. Preferred inert particles are derived from polymeric latices which comprise homopolymers of methylmethacrylate or styrene. The term "photosensitive silver halide emulsion layer" as used herein, is intended to include a first and second photosensitive silver halide layer sensitive to the same portion of the spectrum and in contiguous relation¬ ship i.e., so-called "split emulsions", which will be described below in greater detail. OMPI DETAILED DESCRIPTION OF THE INVENTION The present invention will be described with respect to dye developers as the dye image-forming materials although it will be understood that other dye image-forming materials may be employed in the present invention. Dye developers are well known in the art. A dy developer is a compound which contains a silver halide developing moiety and the chromophoric system of a dye. In multicolor processes, a dye developer providing an image dye of appropriate color is associated with each silver halide emulsion layer; for example, a cyan dye developer with a red sensitive silver halide layer; a magenta dye developer with a green sensitive silver halid emulsion layer; and a yellow dye developer with a blue sensitive silver halide emulsion layer. Unoxidized dye developer is insoluble in water but soluble and mobile in aqueous alkali. Oxidation of the dye developer as a result of development of exposed silver halide results in its immobilization, while unoxidized dye developer can diffuse to the dyeable image-receiving layer producing a positive image therein. To provide rapid transfer of the unoxidized dye developer and to avoid any unwanted interactions in the negative, it is preferred that the unoxidized dye develop pass through the associated silver halide emulsion layer as rapidly as possible consistent with development thereo Since gelatin swells to a considerable degree upon contac with the photographic processing composition and thus would be a factor in slowing dye developer transfer, it i desirable to form the silver halide emulsion layer with a minimum of gelatin. The minimum quantity of gelatin employed, however, is controlled to a great degree by the size of the silver halide grains. Thus, it is desirable to employ sufficient gelatin to retain the silver halide grains within the layer, that is, to prevent any projecti of the grains or portion of the grains through the gelati layer at the interface into contact with adjacent layers. Thus, it will be seen that larger size grains, as commonly employed for high speed emulsions, would require more gelatin than smaller grains at the same unit weight coverage to form a continuous layer without any projection of the grains into contact with adjacent layers. By means of the present invention it has now been found that the transfer of image-forming materials through gelatin-silver halide emulsion layers can be accelerated, while at the same time completely retaining the silver halide grains within the layer and without adversely affecting the photographic properties of the film unit. In fact, unexpected photographic advantages are achieved as evidenced by H & D curves showing a reduction in slope, increased toe extent and enhanced dynamic range. As stated above, these advantages are achieved by disposing in the gelatin-silver halide layer inert particles which are substantially non-swelling in aqueous alkali; which are compatible with gelatin to avoid coagula¬ tion within the layer; which possess a refractive index sufficiently close to that of gelatin to avoid undue light scattering; which are substantially non-film forming (film forming would further inhibit dye transfer) and which are sufficiently hard to retain their physical identity as individual particles in the presence of aqueous alkali and thus provide a non-swelling, sizeable mass to bulk the gelatin layer. Inert particles suitable for use in the present invention include starch, barium sulfate, calcium carbonate, cellulose esters such as cellulose acetate propionate, cellulose esters such as ethyl cellulose, gloss, synthetic resins such as polyvinyl acetate, polycarbonates, homo and copolymers of styrene, inorganic oxides such as zinc oxide, silica, titanium dioxide, magnesium oxide and aluminum oxide, as well as hardened gelatin grains, calcium sulfate, barium carbonate and the like. As stated above, the preferred inert particles OMPP for use in the present invention are polymethylmeth- acrylate and polystyrene and are provided for the film unit by disposing polymethylmethacrylate latex or polystyrene latex in the emulsion. The film forming and hardness characteristics of polymers are properties associated with the glass tr sition temperature of the polymer. Thus, the Tg of the polymer should be above the temperature at which the polymer is dried. Preferably, the Tg is above 35 C, mo preferably, above 60 C. In a particularly preferred embodiment, the Tg is above 100°C. It should be understood that the polymer late may be a homopolymer or a copolymer provided that the comonomers do not modify the copolymer to the extent th the required properties are not retained. The inert particles should be no larger than silver halide grains with which they are associated. I the present invention the maximum average diameter of t silver halide grains is 2.5 microns or less and prefera less than 2.0 microns. Thus, the maximum average diamet of the inert particles is 2.5 microns. The lower limit the particles is determined by the fact that one should avoid packing of the particles such as would impede dye transfer. Preferably, inert particles not less than 0.0 microns in diameter would be employed. In a particularly preferred embodiment the ine particles leave an average diameter which is 10-15% of t average diameter of the silver halide grains associated therewith. The quantity of polymer latex to be employed be readily determined for any given silver halide emulsi For a given silver halide grain size, as the quantity of gelatin decreases, the polymer gelatin ratio goes up to keep the layer dimensions the same. Sufficient gelatin must be present to keep the layer intact and prevent dus of the polymer particles. Preferably, a ratio (weight basis) of 0.5 to 1 to 10 to 1 polymer latex (solids) to gelatin is employed. Particularly preferred is a 1 to 1 ratio for fine grains (less than about ± 4 ) and 6 to 1 for coars grains (greater than about 1.3^ ) . Thus, in a preferred embodiment, the average mean diameter of the fine grains is less than about 1 and the large grains, greater than 1.3^ . . As stated above, the novel photosensitive silver halide layer of the present invention may comprise a first and second photosensitive silver halide layer in contiguous relationship and which are responsive to substantially the same spectral range. Thus, in an alternative embodiment, the diffusion transfer photographic film unit of the present invention comprises a plurality of layers which include a first photosensitive silver halide emulsion layer comprising silver halide grains of a first mean particle size and a second photosensitive silver halide emulsion layer compris- ing silver halide grains of a second mean particle size; said first and second silver halide emulsion layers being in contiguous relationship with the first silver halide layer being distal to the exposure surface of the film unit with respect to the second silver halide layer; said first and second silver halide layers being free of dye image- forming material but . having associated therewith a dye image-forming material which is diffusible as function of the point-to-point degree of silver halide exposure to actinic radiation, and a layer adapted to receive image- forming material " diffusing thereto and means for applying an aqueous processing composition therebetween; wherein at least one of said silver halide layers comprise gelatin and inert particles as defined above. If inert particles are employed in only one layer it is in the layer containing the larger silver halide grains. The intrinsic speed of the second silver halide emulsion layer is greater than that of the first silver halide emulsion layer. However, when the thickness of the gelatin associated with the layers falls to about 50% or less of the mean volume diameter of the grains, the coated layers do not retain their integrity but rather combine, inter¬ mixing the grain sizes, so that the resulting combined OMPI WIPO silver halide layer functions as if a single layer of blended grain sizes were coated, thus losing all the benefits achieved in a layered structure and introducing the drawbacks of the single layered, low gelatin system. it is believed that the advantages of this inv tion result, at least in part, by maintaining better sep tion of the development process of the individual grains well as separation of the by-products of development by virtue of incorporating the above-described inert partic By employing such inert particles in the layers, the lay retain their integrity with the differently sized silver halide particles retained in their own separate and dis¬ tinct layer. As stated above, the intrinsic speed of the second silver halide layer, i.e., the layer closest to t exposure surface, possesses a higher intrinsic speed tha the first silver halide layer. Preferably, the speed di ference is at least about 2 stops and may range up to ab 8 stops. In a particularly preferred embodiment, the difference is about 5 stops. The polymeric latices preferred for employment the present invention may be prepared by known technique The following non-limiting example illustrates the prepa tion of a latex preferred for use in the present inventi Example A Water 118 1. Methyl methacrylate 51 ] < _q _ Potassium persulfate 0.15 kg. Ascorbic acid 0.01 kg. Dowfax 2Al 20% solution 1.275 k (dodecyldiphenyl oxide disulfonate sodium salt, sold by Dow Chemical Co., Midland, Michigan) A reactor was charged with 102 1. of demineral ized water and the Dowfax 2A1 and heated under nitrogen to 83 C whereupon 7.65 kg. of methyl methacrylate was ad "gJ and mixed until the temperature returned to 83°C. After 5 min. at 83°C, 4.93 kg. of initiator solution (0.15 kg. of potassium persulfate and 14.79 kg. water) was added. After the exother , the temperature was reduced to 85 C and the remaining methyl methacrylate was added at a rate of about 361 g/min. and the remaining initiator solution at a rate of about 111 g/min. At the end of the monomer and initiator addition, the temperature was maintained at 85°C for 10 min. and then the ascorbic acid was added. The resulting latex had a 30% solids and the latex parti¬ cles had an average diameter of about a 0.12^. The following non-limiting examples illustrate the present invention: EXAMPLE 1 (Control) A photosensitive element was prepared by coating, in succession, on a gelatin subbed, opaque polyethylene terephthalate film base, the following layers. 1. a layer comprising the cyan dye developer dispersed in gelatin and coated at a coverage of about 2 2 747 mgs/ of dye, about 1554 mgs/m of gelatin, about 2 270 mgs/m of 4 '-methylphenylhydroquinone, and about " REX^ 270 mgs/m of 2-phenyl benzimidazole; 2. a red-sensitive gelatino silver iodobromid emulsion layer comprising a 50/50 blend of 1.05/^and 2 1.5Λ.grains coated at a coverage of about 1280 mgs/m of silver and about 768 mgs/m 2 of gelatin; 3. an interlayer coated at a coverage of abou 2 2500 mgs/m of a 60-30-4-6 tetrapolymer of butylacrylate, diacetone acrylamide, styrene and methacrylic acid, and about 77 mgs/m 2 of polyacrylamide; 4. a layer comprising the magenta dye develop dispersed in gelatin and coated at a coverage of about 646 mgs/m 2 of dye and about 426 mgs/m2 of gelatin and abo 2 229 mgs/m of 2-phenylbenzimidazole; 5. a green-sensitive gelatino silver iodobrom 2 emulsion layer coated at a coverage of about 753 mgs/m o 2 silver' and about 347 mgs/m of gelatin; 6. an interlayer containing the tetrapolymer referred to above in layer 3 at a coverage of about 1369 mgs/m 2, about 24 mgs/m2 of polyacrylamide, and about 2 75 mgs/m succindialdehyde; 7. a layer comprising the yellow dye developer dispersed in gelatin and coated at a coveraσe of about 2 n 968 mgs/m of dye and about 450 mgs/m" of elatin and about 2 208 mgs/m of 2-phenyl benzimidazole; 8. a blue-sensitive gelatino silver iodobromide 2 emulsion layer coated at a coverage of about 1280 mgs/m of silver, about 743 mgs/m 2 of gelatin, and about 204 mgs/m2 of 4'-methylphenylhydroquinone; 9. an overcoat layer coated at a coverage of about 484 mgs/m 2 gelatin and 43 mgs/m2 of carbon black. An image-receiving element was prepared by coat¬ ing the following layers in succession on a 4 mil polyethy¬ lene terephthalate film base, said layers respectively comprising: 1. as a polymeric acid layer, the partial butyl ester of polyethylene/maleic anhydride copolymer at a " 2 coverage of about 28,000 mgs/m ; 2. a timing layer containing about a 75:1 ratio of a 60-30-4-6 copolymer of butylacrylate, diacetone acrylamide, styrene and methacrylic acid and polyvinyl ^^ — Weight Potassium hydroxide 5.25 N-phenethyl-α-picolinium 1.27 bromide (50% solution in water) Sodivim carboxymethyl hydroxethyl cellulose 2.0 (Hercules Type 420H) Titanium dioxide 37.4 6-methyl uracil 0.7 bis-(β-aminoethyl) -sulfide 0.022 Benzotriazole 5.48 Colloidal silica aqueous 0.55 dispersion (30% Si0 2 ) N-2-hydroxyethyl-N,N',N'-tris- 0.75 carboxymethyl-ethylene diamine 4-aminopyrazolo (3, 4d) pyrimidine 0.25 6-benzylamino-purine 0.41 Polyethylene glycol 0.45 (molecular weight 4,000) Water 44.26 EXAMPLE 2 A second film unit was prepared as described above except that layer 2, the green-sensitive silver halide 2 emulsion layer additionally contained 120 mgs/ft 2 (1292 mgs/m •) (solids) of a polymethylmethacrylate latex having an average particle size of about 0.125 and layer 6 was reduced in coverage by 40%. The film units were processed in the following manner: The film unit was exposed with white light to a multicolor target and the processing composition was spread between the two elements in a layer approximately 0.0028" thick in the dark. The following sensitometer data (green light reflection data in neutral column) was obtained in the resulting multicolor reflection prints: ' f0 " EA OMPI * TABLE 1 Control Example Slope 1.61 1.31 Toe Extent 34 48 Dynamic Range 17 23 1.5 Speed 2.11 2.16 0«45 Speed • 1.46 1.34 From the foregoing it can be seen that a 30 un reduction in slope is achieved; an increase in toe exten of about 14 units as well as an increase in dynamic rang of more than 5 units. The loss indicated in the other properties is not considered significant; i.e., the advantages far outweigh the slight decrease recorded in D and speed which, in fact, may be within experimenta error. It should be understood that these enhanced phot graphic results are obtained at the same time the magent dye transfer is accelerated. . EXAMPLE 3 To illustrate the rapid dye transfer achieved the novel invention the following structures were prepar 2 A. On a polyester base was coated 25 mgs/ft (269 mgs/m 2) of the cyan dye of Example 1; 50 mgs/ft2 (538 mgs/m 2) of gelatin and 2 mgs/ft2 (21.5 mgs/m2) of succinaldehyde. B. Structure A was overcoated with 180 mgs/f (1938 mgs/m 2) of derivatized gelatin. " C. Structure A was overcoated with 180 mgs/f 2 (1938 mgs/m ) of inert gelatin. D. Structure A was overcoated with a mixture gelatin (40 mgs/ft 2) (431 mgs/m2) and polymethylmethacryl 2 _> latex (160 mgs/ft ) (1722mgs/m ) (0.125^average diamete The processing composition described above was spread between the above structures and the superposed dye- image-receiving sheet described in Example.1 in a thickness of 28 mils. The density of dye deposited in the receiving sheet was measured as a function of time. The resulting data are set forth below: TABLE 2 Density Overcoat Coverage mgs/ft 2 mgs/m2 3 300 sseecc.. 1 min . 1.5 min. 3 min. 5 rain. A None 0 0.88 1. 16 1.26 1.82 1.94 B Derivatized gelatin 180 0.29 0. 65 0.84 1.06 1.27 C Inert gelatin 180 0.68 0.87 1.00 1.24 • 1.37 D Gelatin 40 Polymethylmethacrylate 160 .81 1. 10 1. 25 1.46 1.55 The above table illustrates the adverse effect gelatin has on dye transfer. The table also shows that a layer with a greater coverage than the gelatin layer but composed of gelatin and latex particles provides transfer rates approaching that obtained with no overcoat at all, especially in the initial time period. The following non-limiting example illustrates a particularly preferred film unit of the present invention: EXAMPLE 4 (Control) A photosensitive element was prepared by coating, in succession, on a gelatin subbed, opaque polyethylene terephthalate film base, the following layers: 1. a layer comprising the cyan dye developer' dispersed in gelatin and coated at a coverage of about 2 2 747 mgs/m ' of dye, about 1554 mgs/m of gelatin, about 2 270 mgs/m of 4'-methylphenylhydroquinone, and about 2 270 mgs/m of 2-phenyl benzimidazole; 2. a red-sensitive gelatino silver iodobromide 2 emulsion layer coated at a coverage of about 1280 mgs/m 2 of silver and about 768 mgs/m of gelatin; 2500 mgs/m diacetone acrylamide, styrene and methacrylic acid, and 2 about 77 mgs/m of polyacrylamide; 4. a layer comprising the magenta dye devel dispersed in gelatin and coated at a coverage of about 646 rags/m 2 of dye and about 426 mgs/m2 of 2 gelatin and about 229 mgs/m of 2-phenylbenzimidazole; 5. a green-sensitive silver halide emulsion unit consisting of a first layer of 0.6Z(.average mean diameter grains coated at a level of about 366 mgs/m 2 o 2 silver and about 161 mgs/m of gelatin and a second lay of 1.4- β average mean diameter grains coated at a level about 387 mgs/m 2 silver and about 186 mgs/m2 of gelatin with a speed difference between said first and second layer of about 5 stops; 6. an interlayer layer containing the tetrapolymer referred to above in layer 3 at a coverage of about 1369 mgs/m 2, about 24 mgs/m2 of polyacrylamide 2 and about 75 mgs/m succindialdehyde; 7. a layer comprising the yellow dye develo dispersed in gelatin and coated at a coverage of about 9G8 mgs/m 2 of dye and about 450 mgs/m2 of gelatin and about 2 208 mgs/m of 2-phenyl benzimidazole; 8. a blue-sensitive gelatino silver iodobromide emulsion layer coated at a coverage of about 1280 mgs/m 2 of silver, about 743 mgs/m of gelatin, and about 204 2 mgs/m of 4'-methylphenylhydroquinone; 9. an overcoat layer coated at a coverage of about 484 mgs/m 2 of gelatin and 43 mgs/m2 of carbon black. EXAMPLE 5 A second film unit was prepared as described except that in layer 5 each green-sensitive silver halide emulsion layer additionally contained 4 times the coverage of gelatin of a polymethylmethacrylate latex having an average particle size of about 0.125 _and layer 6 was reduced in coverage by 40%. The film units of Examples 4 and 5 were pro¬ cessed in the following manner, using the image-receiving element and processing composition described in Example 1. The film unit was exposed to white light and the processing composition was spread between the two elements in a layer approximately 0.0028" thick in the dark. The following sensitometer data (green light reflection data in neutral column) was obtained in the resulting multicolor reflection prints: TABLE 1 Example 3 Exampl Control Slope 1. . 71 1. Toe Extent 37 51 Dynamic Range 17. , 150 28. 1.5 Speed 2 . , 21 2. 0.45 Speed 1. 55 1. From the foregoing it can be seen that a sligh increase in Dmax, a 51 unit reduction in slope, an incre in toe extent of about 14 units as well as an increase i dynamic range of almost 12 units are achieved. The loss indicated in the other properties is not considered sign cant; i.e., the advantages far outweigh the slight decreases recorded in speed. It should be understood th these enhanced photographic results are obtained at the same time the dye transfer is accelerated and silver hal layer integrity maintained. It should be noted that the interlayer (layer adjacent the silver halide emulsion layer containing the inert particles was reduced in coverage by 40%. This is an additional and unexpected advantage of the present invention which further enhances dye transfer. A film unit similar to Example 5 was prepared except th?t the polymer latex employed was a 90/10 methylmethacrylate/hydroxypropyl acrylate copolymer. Up exposure and processing similar advantageous results wer obtained. " 0

Claims: 1. A photosensitive element for use in a diffusion transfer film unit which comprises a support carrying at least one photosensitive silver halide layer having a dye image-forming material associated therewith, wherein said silver halide layer comprises gelatin and inert, particles which are substantially non-swelling in aqueous alkali, compatible with gelatin and substantially non-film forming; said inert particles being less than or equal to the silver halide grains in average diameter; said silver halide grains being 2.5 microns or less in average diameter. 2. The element of claim 1 wherein said photo¬ sensitive silver halide layer comprises, a) a first photosensitive silver halide layer distal to the exposure surface of said element and com¬ prising silver halide grains possessing a first mean particle size; b) a second photosensitive silver halide layer having a second mean particle size; said second photosen- sitive layer having a higher intrinsic speed than said first photosensitive silver halide layer; said first and second photosensitive silver halide layers being in contiguous relationship; said inert particles being dis¬ posed in at least said second silver halide layer; _ 3. The element of claims 1 or 2 wherein the inert particles . are derived from a polymeric latex. 4. The element of claim ' 3 wherein said polymer is polymethylmethacrylate. 5. The element of claim 3 wherein said polymer is polystyrene. 6. The element of claims 1 and 2 wherein the inert particle to gelatin ratio (by weight) is about 0.5 to- 1 to 10 to 1. 7. The element of claim 6 wherein said inert particle to gelatin ratio is about 1 to 1. 8. The element of claim 6 wherein said inert particle to gelatin ratio is about 6 to 1. 9. The element of claims 1 and 2 wherein sai dye image-forming material is a dye developer. 10. The element of claim 2 wherein the averag mean diameter of said silver halide grains is said first photosensitive silver halide layer is less than about 1 micron and wherein the average mean diameter of said gra in said second photosensitive layer is greater than abou 1.3 microns. 11. The element of claim 2 wherein the speed difference between said first and second photosensitive silver halide layers ranges from about 2 to about 8 stop 12. The element of claim 11 wherein said spee difference is about 5 stops. 13. A diffusion transfer film unit comprising support carrying at least one silver halide emulsion lay having a dye image-forming 'material associated therewith and a dyeable receiving layer adapted to receive a dye image diffusing thereto after photoexposure and processi of said silver halide emulsion layer; wherein said silve halide emulsion comprises gelatin and inert particles wh are substantially non-swelling in aqueous alkali, compat with gelatin and substantially non-film forming; said in particles being less than or equal to the siiver halide grains in average diameter; said silver halide grains be 2.5 microns or less in average diameter. 14. The film unit of claim 13 which includes first and second photosensitive silver halide layer, sai first photosensitive silver halide layer being distal to the exposure surface of said element and comprising silv halide grains possessing a first mean particle size; sai second photosensitive silver halide layer having a secon mean particle size; said second photosensitive layer hav a higher intrinsic speed than said first photosensitive silver halide layer; said first and second photosensitiv silver halide layers being in contiguous relationship; s inert particles being disposed in at least said second silver halide layer. 15. The film unit of claims 13 or 14 wherein said inert particles are derived from a polymer latex. 16. The film unit of claim 15 wherein said polymer is polymethylmethacrylate. 17. The film unit of claim 16 wherein said polymer is a methylmethacrylate/hydroxypropylmethacrylate copolymer. 18. The film unit of claim 15 wherein said polymer is polystyrene. 19. The film unit of claim 15 wherein said polymer to gelatin ratio is about 0.5 to 1 to 10 to 1. 20. The film unit of claim 19 wherein said polymer to gelatin ratio is about 1 to 1. 21. The film unit of claim 19 wherein said polymer to gelatin ratio is about 6 to " 1. 22. The film unit of claim 13 wherein said dye image-forming material is a dye developer. 23. The film unit of claim 13 which includes a rupturable container of processing composition adapted to discharge its contents between a predetermined pair of layers. 24. The film unit of claim 23 wherein said dye¬ able receiving layer is adapted to be superposed over the silver halide emulsion layer subsequent to photoexposure and adapted to be separated therefrom after processing. 25. The film unit of claim 18 which is a perman¬ ent laminate and wherein the image is viewable in said receiving layer without separation of said receiving layer from said film unit. 26. The film unit of claim 14 wherein the mean particle size of said grains in said first photosensitive silver halide layer is less than about 1.0/{and the mean particle size of said grains in said second photosensitive silver halide layer is at least 1.3/»_, 27. The film unit of claim 14 wherein the speed difference between said first and second photosensitive silver halide layers is about 2 to 8 stops. 28. The film unit of claim 27 wherein said speed difference is about 5 stops. JJ E OMPI Λ. WIPO - * • 29. A photographic film unit which comprises, in combination: a photosensitive element having a diffusion transfer image-receiving element affixed at least one edg thereof, said photosensitive element comprising a support carrying: a) a red-sensitive silver halide unit having associated therewith a cyan dye developer; b) a green-sensitive silver halide unit havin associated therewith a magenta dye developer; c) a blue-sensitive silver halide unit having associated therewith a yellow dye developer; wherein at least one of said silver halide units comprises gelatin a inert particles which are substantially .non-swelling in aqueous alkali; compatible with gelatin and substantially non-film forming; wherein said photosensitive and said image-receiving elements are adapted to be superposed wit the support layers outermost; said inert particles being less than or equal to the silver halide grains in average diameter; said silver halide grains being 2.5 microns or less average diameter. 30. The film unit of claim 28 wherein at least one of said silver halide units comprises, 1. a first photosensitive silver halide layer distal to the exposure surface of said film unit and com¬ prising silver halide grains possessing a first mean particle size; 2. a second photosensitive silver halide laye having a second mean particle size; said second photosen- sitive layer having a higher intrinsic speed than said fi photosensitive silver halide layer; said first and second photosensitive silver layers being in contiguous relation ship; said inert particles being disposed in at least sai second silver halide layer. 31. The film unit of claims 28 and 29 wherein said inert particles are derived from a polymer latex. 32. The film unit of claim 30 including a rup- turable container retaining an aqueous alkaline processin - Q O composition and adapted to discharge its contents inter¬ mediate said superposed photosensitive and image-receiving elements. 33. The film unit of claims 28 and 29 wherein the support layer of said image-receiving element is trans¬ parent. 34. The film unit of claim 33 in which said unit is a composite structure comprising said photosensitive element and said image-receiving element permanently affixed to the other in superposed relationship, the support layers of each of said elements being outermost. 35. The film unit of claim 28 wherein said poly¬ mer latex is disposed in said green-sensitive silver halide unit. 36. The film unit of claim 30 wherein said poly¬ mer is polymethylmethacrylate. 37. The film unit of claim 30 wherein said poly¬ mer is polystyrene. 38. The film unit of claim 28 wherein said poly- mer to gelatin ratio (by weight) is about 0.5 to 1 to 10 to 1. 39. The film unit of claim 38 wherein said polymer to gelatin ratio is about 1 to 1. 40. The film unit of claim 38 wherein said poly- mer to gelatin ratio is about 6 to 1. 41. The film unit of claim 29 wherein the mean particle size of said grains in said first photosensitive silver halide layer is less than about l.O ^and the mean particle size of said grains in said second photosensitive silver halide layer is at least 1.3 42. The film unit of claim 40 wherein the speed difference between said first and second photosensitive silver halide layers is about 2 to 8 stops. 43. The film unit of claim 41 wherein said speed difference is about 5 stops. 44. A photosensitive element for use in a diffusion transfer film unit which comprises a support carrying: - E ^- OMPI a) a first photosensitive silver halide layer distal to the exposure surface of said element and com¬ prising silver halide grains possessing a first mean particle size; b) a second photosensitive silver halide laye having a second mean particle size; said second photosen¬ sitive layer having a higher intrinsic speed than said fi photosensitive silver halide layer; said first and second photosensitive silver halide layers being in contiguous relationship and having associated therewith a dye image forming material which is diffusible during processing as a function of the point-to-point degree of silver halide exposure to actinic radiation; said first and second phot sensitive silver halide layers comprising gelatin and ine particles ' which are substantially non-swelling in aqueous alkali, compatible with gelatin, and substantially non- film forming; said inert particles being equal to or less than the silver halide grain in average diameter; said silver halide grains being 2.5 microns or less in average diameter. 45. A photographic diffusion transfer film uni comprising a support carrying at least one photosensitive element comprising a first and second photosensitive silv halide layer and a dyeable receiving layer adapted to receive a dye image diffusing thereto after photoexposure and processing of said photosensitive element, said first photosensitive silver halide layer being distal to the exposure surface of said element and comprising silver halide grains possessing a first mean particle size; said second photosensitive silver halide layer having a second mean particle size; said second photosensitive layer havi a higher intrinsic speed than said first photosensitive silver halide layer; said first and second photosensitive silver halide layers being in contiguous relationship and having associated therewith a dye image forming material which is diffusible during processing as a function of th point-to-point degree of silver halide exposure to actini radiation; said first and second photosensitive silver halide layers comprising gelatin and inert particles which are substantially non-swelling in alkali, compatible with gelatin, and substantially non-film forming; said inert particles being less than or equal to the silver halide grains in average diameter; said silver halide grains being 2.5 microns or less in average diameter. 46. A photographic film unit which comprises, in combination: a photosensitive element having a diffusion trans- fer image-receiving element affixed at least one edge thereof, said photosensitive element comprising a support carrying: a) a red-sensitive silver halide unit having associated therewith a cyan dye developer; b) a green-sensitive silver halide unit having .associated therewith a cyan dye developer; c) a blue-sensitive silver halide unit having associated therewith a yellow dye developer; wherein at least one of said silver halide units comprises: 1) a first photosensitive silver halide layer distal to the exposure surface of said film unit and com¬ prising silver halide grains possessing a first mean particle size; 2) a second photosensitive silver halide layer having a second mean particle size; said second photosen¬ sitive layer having a higher intrinsic speed than said first photosensitive silver halide layer; said first and second photosensitive silver hlaide layers being in contiguous relationship and having associated therewith a dye image forming material which is diffusible during processing as a function of the point-to-point degree of silver halide exposure to actinic radiation; said first and second photo¬ sensitive silver halide layers comprising gelatin and inert particles which are substantially non-swelling in alkali, compatible with gelatin, and substantially non-film forming; said inert particles being less than or equal to the silver halide grains in average diameter; said silver halide grains being 2.5 microns or less in average diameter wherein said OMPI ° ph o t osens iti ve an d said image-receiving elemen t s a re a d ap t e d t o b e su p er p osed with the support layers ou t er- most. "sTξJ O J

Inventors: KLIEM P
Applicants: POLAROID CORP
Application year: 1979
Main classification: G03C1
IPC codes: G03C1, G03C8