SE450797B - PHOTOGRAPHIC FILM UNIT FOR IMAGE TRANSFER INCLUDING AT LEAST ONE EMULSION LAYER INCLUDING PLATE SILVER HALOGENID CORN - Google Patents

Description

15 20 25 30 35 40 450 797 in the 2 traps can be volatile, and the photographer needs such a near instantaneous visual verification of an acceptable photographic image that can be achieved.

Although image transfer has reduced the time required for the availability of the image in silver halide photography, this advantage has not been achieved without other sacrifices. A significant long-term problem with image transfer photography is associated with the consumption of silver. Multicolored photographic silver halide elements that are treated conventionally and film units for dye image transfer both use relatively high silver coatings to achieve maximum photographic sensitivity. Typically, about 1000 mg of silver per square meter is required to form each of the exposures of exposure in blue, green and red.

In conventionally treated, multicolored photographic elements, the produced image contains no silver, and all the silver present in the photographic element can in theory be recycled. On the other hand, silver is rarely recycled in image transfer photography, and in film units in one piece for car transfer, all silver remains with the photographic film units that provide the visible image.

Another inconvenience associated with image transfer photography as such is the decrease in image sharpness that can be attributed to diffusion. When the imaging materials diffuse from the silver halide emulsion layer or an adjacent, dye-releasing layer, diffusion occurs both toward the receiving layer and laterally, leading to image scattering and loss of sharpness. The sharpness can be improved by reducing the length of the diffusion path to the receiver layer. This is determined by the number and thickness of the layers to be examined. Unfortunately, the minimum thickness of the silver halide emulsion layer is limited by the size of the silver halide grains and the weight ratio of gelatin to silver halide. In film units for multicolor car transfer, in which three superimposed, dye-emitting layer units are used, intermediate, dye-emitting layer units and separating intermediate layers must be permeated by diffusing dyes which migrate to the receiving layer.

Another condition that arises in image transfer photography is a variation in the image density as a function of temperature differences. Since the subjects are presented in different temperature conditions, and since the essential advantage of image transfer photography is the rapid availability of the image, it follows that the ability of photographic image transfer elements to provide acceptable images at different temperatures are also important. Image transfer photography is very different from conventional photography in this respect, since in the latter development it is seldom carried out without control of the temperature.

A number of limitations regarding image generation arise when creating transferred images with dyes. For example, both the high silver coatings indicated above and the stoichiometrically predicted amounts of dye imaging material are required to provide transferred dye images with acceptable maximum densities. To the extent that the efficiency of the color transfer deteriorates from stoichiometrically predicted values, more dye-imaging materials must be incorporated into the photographic elements and thus the layer thicknesses increased to incorporate increased amounts of these materials. Furthermore, the rate of release of dyes for transfer can affect the time required to produce a visible image. When the prevention of dye transfer is based on the reaction product from the development, as in the case of many conventional, positive-working dye imaging agents, the rate of silver halide development is also limited by the maximum rate at which the dye becomes available for transfer, of image dye in relation to the development rate of silver halide can cause a loss in the resolution of the image. Improvements in any or a combination of these properties can, of course, significantly improve dye image transfer.

A large variety of regular and irregular grain shapes has been observed in photographic silver halide emulsions, intended for image applications. Regular grains are often cubic or octahedral. The edges of the grains may be rounded due to ripening effects, and in the presence of strong ripening agents, such as ammonia, the grains may even be spherical or be present as thick plates which are almost spherical, as described in, for example, U.S. Pat. 871 and Zelikman and Levi: Making and Coating Photographic Emulsions, Focal Press, 1964, p. 223. Rods and flat grains in varying proportions have often been observed mixed with other cora forms, especially when the pAg (the negative logarithm of the silver ion content) of the emulsions has varied during the precipitation, such as occurs in, for example, single-ray precipitates.

Flat grains (those whose area is extended in two dimensions in comparison with their thickness) have been studied in detail, often in macro sizes that have no photographic use.

Flat grains are defined herein as those having two parallel or substantially parallel crystal surfaces, each of which is substantially larger than any other single crystal surface of the grain.

A discussion of flat bromoiodide grains can be found in Duffin: Photographic Emulsion Chemistry, Focal Press, 1966, pp. 66-72, 'and Trivelli and Smith: "The Effect of Silver Iodide Upon the Structure of Silver Bnmn-Iodide Precipitation Series", The Photographic Journal , vol. LXXX, July 1940, pp. 285-288.

Trivelli and Smith observed a marked decrease in both grain size and width ratio with the addition of iodide. Emulsions with flat silver bromide are discussed by de Cugnac and Chateau, "Evolution of the Morphology of Silver Bromide Crystals During Physical Ripening", Science et Industries Photographiques, vol. 33, No. 2 (1962), pp. 121-125.

Flat grain grain sulfur sensitized silver bromide emulsions having an average aspect ratio of about 5 to 7: 1, wherein the flat grains account for more than 50% of the projected area of the total grain population were incorporated into a radiographic direct X-ray product, No Screen X-Ray Code 5133. marketed by Eastman Kodak Oo from 1937 to the 1950s. Gutoff, "Nucleation and Growth Rates During the Precipitation of Silver Halide Photographic Emulsions", Photographic Sciences and Engineering, vol. 14, No. 4, July-August 1970, pages 248-257, describes the preparation of silver bromide and silver bromoiodide emulsions of the type prepared by single jet precipitations using a continuous precipitation apparatus.

Processes have recently been published for the preparation of emulsions in which a major proportion of the silver halide is in the form of flat grains. U.S. Pat. No. 4,063,951 discloses the production of flat-shaped silver halide crystals which are bounded by cubic surfaces [100] and which have a width ratio (based on edge length) of from 1.5 to 7: 1. The flat grains have square and rectangular main surfaces which are characteristic of crystal surfaces [100]. U.S. Patent No. 4,067,739 discloses the preparation of silver halide emulsions in which most crystals are of the twin octahedral type, by the production of seed crystals, by Ostwald ripening in the presence of a silver halide solvent, and completion of grain growth without regrowth or Ostwald ripening , under the control of pBr (the negative logarithm of the bromide ion content) .r. U.S. Patents 4,150,994 and 4,184,877, British Patents 1,570,581 and German OLS 2,905,655 and 2,921,077. configuration by using graft crystals which at least 90 mol% consist of iodide. (Unless otherwise indicated, all references to percentages of halide based on silver are present in the corresponding emulsion, grain or grain range under discussion, and contain, for example, a grain consisting of silver bromoiodide, containing 40 mole percent iodide, also 60 mole percent bromide.) Several of the above-mentioned references indicate an increased coverage of the emulsions and that they are useful in films for cameras, both for black and white and for color. U.S. Patent No. 4,063,951 specifically discloses an upper limit of 7: 1 aspect ratio, and from the very low aspect ratios obtained by the examples (2: 1 aspect ratio), the 7: 1 aspect ratio appears to be unrealistically high. It is clear from the repetition of examples and consideration of published photomicrographs that the width ratios achieved in the other references mentioned above were also less than 7: 1.

According to the present invention there is provided a photographic film unit for image transfer, comprising a carrier, at least one emulsion layer applied to the carrier, containing a dispersion medium and radiation-sensitive silver halide grains, and an image receiving layer, characterized in that at least 50 percent of the total projected area of the radiation-sensitive silver halide grains in at least one emulsion layer are provided by flat silver halide grains with a thickness of less than 0.5 μm, a diameter of at least 0.6 μm, the diameter of a grain being defined as the diameter of a circle with an area which is equal to the projected area of the grain, and an average width ratio greater than 8: 1, the width ratio being defined as the ratio between the diameter of the grain and its thickness. It is an advantage of the present invention that the photographic film units for image transfer can provide visible images with less time required after the onset of development. The film units for image transfer also provide higher intermediate contrasts as a function of the required development time. The image transfer film units can produce images with improved sharpness. The present invention is particularly advantageous in that it enables a reduction in silver coatings without loss of photographic sensitivity, with more efficient use of dye imaging agents, more favorable arrangements of layering, elimination or reduction of yellow filter material, and a lesser dependence on the image of the temperature. . Still other photographic advantages are provided by various specific forms of the image transfer film units described in the following.

The use of chemically and spectrally sensitized high grain width emulsion emulsions in the image transfer film units of the invention provides further significant advantages in the relationship between sensitivity and graininess, sharpness and differences between sensitivity in blue and minus-blue. "The emulsions with flat grains with The width ratio improves the sharpness of the underlying emulsion layers when they are applied to receive light which is free from substantial scattering.These emulsions are particularly effective in this respect when they are applied in emulsion layers closest to the source of exposing radiation.

When spectrally sensitized outside the blue part of the spectrum, the flat grain grains of the silver bromide and bromoiodide emulsions show a greater separation in their sensitivity in the blue region of the spectrum compared to the region of the spectrum for which they are spectrally sensitized. .

Silver bromide and bromoiodide emulsions with flat grain grains with high aspect ratio that are sensitized in minus blue are much less sensitive to blue light than to minus blue light and do not require filter protection to provide acceptable exposure registrations in minus blue. when exposed to neutral light; such as daylight at 5500 ° K. The flat grain emulsions with high aspect ratio show improved relationships between sensitivity and graininess compared to previously known flat grain emulsions and in comparison in general with the best relationships between sensitivity and graininess achieved so far with emulsions with the same halide content. Very large increases in bluish sensitivity of high grain ratio bromide and bromine iodide emulsions are obtained compared to their original bluish sensitivity when blue spectral sensitizers are used.

The invention can be better understood with reference to the following detailed description in connection with the drawing, in which Fig. 1 is a diagram of the silver coating with respect to the relative sensitivity, wherein A constitutes a control sample and B shows the invention.

Silver halide emulsions In order to achieve the advantages of the invention, at least one emulsion layer is formed in the film unit for image transfer of a silver halide emulsion with flat grains with a high aspect ratio. With respect to the silver halide emulsions of the present invention, the term "High Width Ratio" is defined herein as requiring that the silver halide grains having a thickness of less than 0.5 μm, preferably less than 0.3 μm, and a diameter of at least 0.6 μm, has an average aspect ratio greater than 8: 1 and accounts for at least 50 percent of the total projected area of the silver halide grains.

The preferred high width flat grain silver halide emulsions in the image transfer units of the present invention are those in which the silver halide grains having a thickness of less than 0.5 μm (preferably less than 0.3 μm and optionally less than 0.2 μm pm) and a diameter of at least 0.6 pm has an average width ratio of at least 12: 1 and optimally at least 2011.

These silver halide grains have an average diameter of less than 30 Pm (preferably less than 15 Pm and optimally less than 10 Pm). In a preferred form of the invention, these silver halide grains account for at least 70 percent and optimally at least 90 percent of the total projected area of the silver halide grains.

It will be appreciated that the thinner the flat grains corresponding to a given percentage of the projected area, the higher the average width ratio of the emulsion. Typically, the flat grains have an average thickness of at least 0.03 μm, although still barrel flat grains can in principle be used, e.g. as little as 0.01 Pm.

The above-described grain properties of the silver halide emulsion of the present invention can be readily determined by methods well known to those skilled in the art. The term "width ratio" as used herein refers to the relationship between the diameter of the grain 10 15 20 25 30 35 40 450 797 s and its thickness. The "diameter" of the grain is in turn defined as the diameter of a circle having an area equal to the projected area of the grain, seen in a photomicrograph or an electron micrograph of an emulsion sample. From shaded electron micrographs of emulsion samples it is possible to determine the thickness and diameter of each flat grain and to identify the flat grains having a thickness of less than 0.5 μm (or 0.3 μm) and a diameter of at least 0.6 pm. From this, the width ratio of each such flat grain can be calculated, and the width ratios of all the flat grains in the sample which meet the criteria of thickness and diameter can form an average value for obtaining their average width ratio. By this definition, the average width ratio is the mean value of individual width ratios of flat grains. In practice, it is usually easier to obtain an average thickness and an average diameter of the flat grains having a thickness of less than 0.5 or 0.3 μm and a diameter of at least 0.6 μm and to calculate the average width ratio as the ratio between these two averages. Regardless of whether the average of the individual width ratios or the average of thickness and diameter is used to determine the average width ratio, the average width ratios obtained differ significantly within the tolerances for grain measurements that are possible. The projected areas of the silver halide grains meeting the criteria of thickness and diameter can be summed, the projected areas of the remaining silver halide grains in the photomicrograph can be summed separately, and from the two sums the proportion of the total projected area of the silver halide grains can be calculated are provided by the flat grains which meet the criteria of thickness and diameter.

In the determinations above, a reference thickness of the flat grains of less than 0.5 and preferably less than 0.3 μm has been selected to distinguish the uniquely thin, flat grains which are possible here from thicker flat grains which give inferior properties of the emulsion. A reference grain diameter of 0.6 μm was chosen, since with smaller diameters it is not always possible to distinguish between flat and non-flat grains in micrographs. The term "projected area" is used in the same sense as the terms "projection area" and "projective area", which are commonly used in the field, see, for example, James and Higgins, Fundamentals of Photographic Theory, Morgan and Morgan, New York, page 15. u: 10 The flat grains may have any crystal halide crystal composition known to be useful in photography.

In a preferred embodiment that provides a wide range of observed benefits, high width ratio silver bromoiodide emulsions are used in the present invention.

Silver bromoiodide emulsions with flat grains with a high width ratio can be prepared by the following precipitation procedure: In a conventional reaction vessel for precipitating silver halide, provided with an efficient stirring apparatus, a dispersing medium is charged. Typically, the dispersant medium initially charged to the reaction vessel constitutes at least about 10% by weight, preferably then 20-80% by weight, based on the total weight, of the dispersant medium present in the silver bromoiodide emulsion at the end of the grain precipitation. Since dispersant medium can be removed from the reaction vessel by ultrafiltration during the precipitation of silver bromoiodide grains, as taught in Belgian patent specification 886 645, corresponding to French patent specification Z 471 620, it will be appreciated that a volume of dispersant medium with or even greater than the volume of the silver bromoiodide emulsion present in the reaction vessel at the end of the grain precipitation. The dispersing medium initially charged to the reaction vessel is suitably water or a dispersion of peptizing agent in water, optionally containing other constituents, such as one or more silver halide and / or metal dopants, which are more specifically described below. When a peptizing agent is present from the beginning, it is suitably used at a level of at least 10 percent and preferably at least 20 percent of the total peptizing agent present in the completion of the precipitation of silver bromoiodide. Additional dispersant medium is added to the reaction vessel with the silver and halide salts and can also be added in a separate jet. It is common practice to set the proportion of dispersant medium, especially to increase the proportion of peptizing agent, after the completion of the salt additives. . A small proportion, typically less than 10 percent of the bromide salt used in the preparation of the silver bromoiodide grains is present from the beginning in the reaction vessel to adjust the content of bromide ions in the dispersing medium at the beginning of 10 'ß 20 25 30 35 40 450 797 Ä 10 the silver bromoiodide precipitate. The dispersant medium in the reaction vessel is also from the beginning substantially free of iodide ions, since the presence of iodide ions before a simultaneous addition of silver and bromide salts favors the formation of thick and non-flat grains. The term "substantially free of iodide ions" as used herein, applied to the contents of the reaction vessel, implies that there is an insufficient amount of iodide ions present in comparison with bromide ions to precipitate as a separate silver iodide phase. It is preferred to keep the iodide content at less than 0.5 mol% of the total halide ion content present before the silver salt addition in the reaction vessel. If the pBr of the dispersion medium is initially too high, the formed, flat silver bromoiodide grains will be comparatively thick and therefore have a low width ratio. It is possible from the outset to maintain pBr in the reaction vessel at or below 1.6, suitably below 1.5. On the other hand, if the pBr is too low, the formation of non-flat silver bromoiodide grains is favored. It is therefore possible to keep the pBr in the reaction vessel at or above 0.6, preferably above 1.1. pBr is defined here as the negative logarithm of the bromide ion content. Both pH and pAg are defined in a similar way for the levels of hydrogen and silver ion, respectively.

During the precipitation, silver, bromide and iodide salts are added to the reaction vessel by methods well known in the precipitation of silver bromoiodide grains. Typically, an aqueous solution of a soluble silver salt, such as silver nitrate, is introduced into the reaction vessel at the same time as the addition of the bromide and iodide salts. The bromide and iodide salts are also typically added as aqueous solutions of salt, such as aqueous solutions of one or more soluble halide salts of ammonium, alkali metal (eg sodium or potassium) or alkaline earth metal (eg magnesium or calcium). The silver salt is added at least at the beginning to the reaction vessel separately from the iodide salt. The iodide and bromide salts can be added to the reaction vessel separately or as a mixture.

With the addition of silver salt in the reaction vessel, the germination stage for grain formation is initiated. A population of barley sprouts is formed which can serve as precipitation points for silver bromide and silver iodide as the supply of silver, bromide and iodide salts continues. The precipitation of silver bromide and silver iodide on existing barley sprouts constitutes the growth stage hl '10 15 20 25 30 35 40 H 450 797 of barley formation. The width ratios of the flat grains formed according to the present invention are less affected by iodide and bromide contents during the growth stage than during the germination stage. It is therefore possible during the growth stage to increase the permissible latitude of pBr while co-adding silver, bromide and iodide salts above 0.6, suitably in the range from 0.6 to 2.2, and most preferably from 0.8 to 1 , 6. It is, of course, possible and in fact preferable to maintain pBr in the reaction vessel throughout the addition of silver and halide salt within the original limits described above prior to the addition of silver salt. This is especially preferred when a substantial rate of formation of barley sprouts continues throughout the supply of silver, bromide and iodide salts, such as in the production of strongly polydisperse emulsions. An increase in the pBr values above 2.2 during the growth of flat grains leads to a thickening of the grains, but can in many cases be tolerated when an average width ratio higher than 8: 1 is still achieved.

As an alternative to the addition of silver, bromide and iodide salts as aqueous solutions, it is possible to add the silver, bromide and iodide salts, at the beginning or at the growth stage, in the form of fine silver halide grains suspended in dispersed medium. The grain size is such that they easily Ostwald ripen on larger barley sprouts if any are present, once introduced into the reaction vessel. The maximum useful grain sizes will depend on the specific conditions of the reaction vessel, such as the temperature and the presence of solubilizing and maturing agents. Grains of silver bromide, silver iodide and / or silver bromo iodide can be added. (Since bromide and / or iodide are precipitated preferentially to chloride, it is also possible to use grains of silver chlorobromide and silver chlorobromoiodide.} The silver halide grains are suitably very fine, eg with an average diameter of less than 0.1 .mu.m.

Depending on the pBr indicated above, the levels and rates of the additions of silver, bromide and iodide salts can be designed in any suitable, conventional manner. The silver and halide salts are conveniently added at levels from 0.1 to 5 moles per liter, although wider, conventional content ranges, such as from 0.01 moles per liter to saturation, are possible. Specifically preferred precipitation processes are those which achieve shortened precipitation times by increasing the rate of addition of silver and halide salts during the process. The rate of addition of the silver and halide salts can be increased either by increasing the rate at which the dispersant medium and the silver and halide salts are added, or by increasing the levels of the silver and halide salts in the dispersing medium being added.

It is especially preferred to increase the rate of addition of silver and halide salt, but to keep the rate of addition below the threshold at which the formation of new barley sprouts is favored, i.e. to avoid new formation of sprouts, as taught by U.S. Patents 3,650,757, 3 672 900 and 4 242 445, German OLS 2 107 118, European patent application _ 80102242, and Wey: "Growth Mechanism of AgBr Crystals in Gelatin Solution", Photographic Science and Engineering, vol. 21, No. 1, January / February 1977, page 14 et seq. By avoiding the formation of additional barley sprouts after the transition to the growth stage of the precipitate, relatively monodisperse populations of flat silver bromoiodide grains can be obtained. Emulsions with coefficients of variation less than about 30 percent can be produced. Here, the coefficient of variation is defined as 100 times the standard deviation of the grain diameter, divided by the mean grain diameter. By deliberately promoting renewed germination during the growth stage of precipitation, it is of course possible to produce polydisperse emulsions with considerably higher coefficients of variation.

The content of iodide in the silver bromoiodide emulsions in the image transfer units according to the invention can be controlled by the addition of iodide salts. Any conventional iodide content can be used. Even very small amounts of iodide, e.g. as little as 0.05 mole percent, are known in the art to have a beneficial effect. In their preferred form, the emulsions contain at least about 0.1 mole percent iodide. Silver iodide can be incorporated into the flat silver bromoiodide grains up to their solubility limit in silver bromide at the grain formation temperature. Thus, silver iodide contents of up to about 40 mole percent can be achieved in the flat silver bromoiodide grains at precipitation temperatures of 90 ° C. In practice, precipitation temperatures can vary down to near room temperature, e.g. about 30 ° C. It is usually suitable for the precipitation to be carried out at temperatures in the range from 40 to 80 ° C. For most photographic applications, it is preferred to limit maximum iodine levels to about 20 mole percent, with optimal iodide levels being up to about 15 mole percent.

The relative proportions of iodide and bromide salts initiated in the reaction vessel during precipitation can be maintained in a certain ratio to form a substantially uniform iodide profile in the flat silver bromoiodide grains, or can be varied to achieve different photographic effects. Advantages in terms of photographic sensitivity and / or graininess arise from increasing the proportion of iodide in annular areas in silver bromoiodide emulsions with high grain ratio with high aspect ratio compared to central areas of the flat grains. Iodide levels in the central regions of the flat grains can be from 0 to 5 mole percent, with at least one mole percent higher iodide levels in the laterally surrounding annular regions up to the solubility limit of silver iodide in silver bromide, suitably up to about 20 mole percent. cents and optimally up to about 1S mole percent. In a variant form, it is possible to complete the addition of iodide or bromide and iodide salt to the reaction vessel before the end of the addition of silver salt, so that excess bromide reacts with the silver salt. This causes a shell of silver bromide to form on the flat silver bromoiodide grains. Thus, it can be seen that the flat silver bromoiodide grains in the image transfer units of the present invention may have substantially uniform or graded iodide content profiles, and that the grading may be adjusted as desired to favor higher iodide contents internally or at or near the surfaces of the silver bromine iodide grains. Although the precipitation of the high-width flat-grained silver bromoiodide emulsions has been described with reference to a process which produces neutral or non-ammoniacal emulsions, the emulsions of the present invention and their usefulness are not limited to any particular process for their preparation. An alternative process is an improvement over U.S. Pat. from the beginning present in the reaction vessel is reduced to below 0.05 μm.

Silver bromide emulsions with flat grains with a high width ratio and which have no iodide can be prepared by the process described in detail above, modified to exclude iodide. Silver bromide emulsions with flat grains with a high width ratio can alternatively be prepared by a process based on that used by Cugnac and Chateau, cited above. Silver bromide emulsions with a high width ratio and containing square and rectangular grains can be produced by a process in which cubic germ grains with an edge length below 0.15 μm are used. While the pAg of the seed granule emulsion is kept in the range from 5.0 to 8.0, the emulsion matures in the substantial absence of non-halide type silver ion complexing agents to give flat silver bromide grains having an average aspect ratio of at least 8: 1. Still other precipitates of silver bromide emulsions with flat grains with a high width ratio and without iodide are shown in the examples.

To illustrate other silver halide emulsions with flat grains having a high width ratio that can be used in the practice of the present invention, reference is made to a method of producing flat silver chloride grains which are internally substantially free of both silver bromide and silver iodide. A double jet precipitation process is used, in which chloride and silver salts are simultaneously initiated in a reaction vessel containing dispersion medium in the presence of ammonia. During the addition of chloride salt, the pAg in the dispersing medium is in the range from 6.5 to 10, and the pH in the range from 8 to 10. The presence of ammonia and high temperatures tends to cause the formation of thick grains.

Therefore, precipitation temperatures are limited to up to 60 ° C to give silver chloride solutions with flat grains with a high width ratio.

It is also possible to produce flat grains with at least 50 mole percent chloride having opposite crystal surfaces lying in the crystalline plane [111], and in a preferred form, at least one peripheral edge lying parallel to a crystallographic vector <211> in the plane of one of the main surfaces. Such flat grain emulsions can be prepared by reacting aqueous solutions of silver salt and chloride halide salt in the presence of an amount which modifies the behavior of the crystals of an aminoazaindene and a peptizing agent having a thioether bond.

Flat grain emulsions can also be prepared in which the silver halide grains contain chloride and bromide in at least annular grain ranges and preferably throughout. The areas in the flat grains containing silver chloride and bromide are prepared by maintaining a molar ratio of chloride to bromide ions from 1.6 to about 260: 1, and the total content of halide ions in the reaction vessel in the range from 0. 10 to 0.90 normal during the addition of silver, chloride, bromide and possibly iodide salts to the reaction vessel. The molar ratio of silver chloride to silver bromide in the flat grains can vary from 1:99 to 2: 3. Emulsions with high grain ratio grains useful in the practice of the present invention can have extremely high average width ratios. The average width ratios of flat grains can be increased by increasing the average grain diameters.

This can provide sharpness benefits, but maximum average grain diameters are generally limited by graininess requirements for a specific photographic application. The average width ratios of flat grains can also or alternatively be increased by reducing the average grain thicknesses. When silver coatings are kept constant, a reduction in the thickness of flat grains generally improves the graininess as a direct function of increasing width ratio.

Accordingly, the maximum average width ratios of the flat grain emulsions of the present invention are a function of the maximum average grain diameters acceptable for the specific photographic application and the minimum acceptable thickness of the flat grains obtainable. Maximum average width ratios have been found to vary, depending on the precipitation method used and the halide composition of the flat grains. The highest observed average width ratios, g S00: 1, for flat grains with photographically usable average grain diameters, have been achieved by making silver bromide grains with Ostwald ripening, whereby width ratios of 100: 1, 200: 1 or even higher can be obtained. achieved by means of double-jet precipitation procedures. The presence of iodide generally reduces the maximum average width ratios achieved, but the production of silver bromine iodide emulsions with flat grains having an average width ratio of 100: 1 or even 200: 1 is possible. Average width ratios as high as 50: 1 or even 10021 for flat grains of silver chloride, optionally containing bromide and / or iodide, can be prepared. The maximum average grain diameters of flat grain emulsions with a high width ratio are in all cases less than 30 [mu] m, preferably less than 15 [mu] m, and optimally not exceeding 10 [mu] m. Modifying compounds may be present during the precipitation of the flat grains. Such compounds may be present from the beginning in the reaction vessel or may be added with one or more of the salts according to conventional methods. Modifying compounds, such as compounds of copper, thallium, lead, bismuth, cadmium, zinc, intercalcogenes (ie sulfur, selenium and tellurium), gold and precious metals of Group VIII may be present during the silver halide precipitation, as shown in U.S. Pat - the documents 1,195,432, 1,951,933, 2,448,060, 2,628,167, 2,950,972, 3,488, 709, 3,737,313, 3,772,031 and 4,269,927, and Research 134, June 1975, item 13452. Research Disclosure and its predecessor, the Product Licensing Index, are publications from Industrial Opportunities Ltd, Homewell, Havant, Hampshire, P09 1EF, UK. The Emulsions with Flat Grains Disclosure, vol. can be sensitized internally during the precipitation, as shown by Moisar et al, Journal of Photographic Science, vol. 25, 1977, pp. 19-27. The individual silver and halide salts can be added to the reaction vessel through surface or subsurface supply tubes, by self-pressure or by supply apparatus to maintain control of the feed rate and pH, pBr and / or pAg of the contents of the reaction vessel, as indicated in U.S. Pat. Nos. 3,821,002 and 3,031,304, and Claes et al., Photographische Korrespondenz, Volume 102, No. 10, 1967, page 162. In order to obtain a rapid distribution of the reactants in the reaction vessel, specially designed mixing devices can be used. as shown in U.S. Patents 2,996,287, 3,342,605, 3,415,650, 3,785,777, 4,147,551 and 4,171,224, British Patent Application 2,022,431A, German OLS 2,555,364 and 2,556,885, and Research Disclosure, 166, February 1978, paragraph 16662.

In the preparation of the emulsions with flat grains, vol. levels of peptizing agents from 0.2 to 10% by weight are used, based on the total weight of emulsion components in the reaction vessel. It is common practice to keep the content of the peptizing agent in the reaction vessel in the range below about 6 percent, based on the total weight, before and during the formation of silver halide, and to adjust the content of emulsion carrier upwards for optimal yields. coating properties through delayed, contributing carrier additives. It is possible that the emulsion formed from the beginning will contain from 5 to 50 grams of peptizing agent per mole of silver halide, preferably then 10 to 30 grams of peptizing agent per mole of silver halide. Additional carriers can be added later to set the content up to as high as 1000 grams per mole of silver halide. Suitably the content of carrier in the finished emulsion is over S0 grams per mole of silver halide. When coating and drying to produce a photographic element, the carrier suitably forms 30 to 70% by weight of the emulsion layer.

Carriers (which include both binders and peptizers) can be selected from those conventionally used in silver halide emulsions. Preferred peptizing agents are hydrophilic colloids, which can be used alone or in combination with hydrophobic materials. Suitable hydrophilic carriers include such substances as proteins, protein derivatives, cellulose derivatives, eg cellulose esters, gelatin, e.g. alkali-treated gelatin (gelatin from beef bones or cowhide) or acid-treated gelatin (pigskin gelatin), and gelatin derivatives such as acetylated gelatin and phthalate gelatin. These and other carriers are described in Research Disclosure, vol. 176, December 1978, paragraph 17643, section IX. The carrier materials, especially when comprising the hydrophilic colloids, as well as the hydrophobic materials useful in combination therewith, can be used not only in the emulsion layers of the photographic elements of the present invention, but also in other layers, such as topcoats, interlayers and applied layers under the emulsion layers.

Grain ripening may occur during the preparation of the silver halide emulsions of the present invention, and it is preferred that grain ripening occur in the reaction vessel during at least the formation of silver bromoiodide grains. Known solvents for silver halide are useful for promoting maturity. For example, an excess of bromide ions present in the reaction vessel is known to promote maturation. It is therefore clear that the bromide salt solution which is introduced into the reaction vessel itself can promote maturation. Other ripening agents may also be used and may not be present at all in the dispersing medium in the reaction vessel before the addition of the silver and halide salt, or they may be added to the reaction vessel together with one or more of the halide salt, the silver salt or the peptizing agent. . In a further variant, the ripening agent can be added independently during the additions of halide and silver salt. Although ammonia is a known ripening agent, it is not a preferred ripening agent for the silver bromoiodide emulsions of the present invention which exhibit the highest achieved relationships between sensitivity and graininess. The preferred emulsions for use in the present invention are non-ammoniacal or neutral emulsions.

Among preferred ripeners are those containing sulfur.

Thiocyanate salts can be used, such as the alkali metal salts, most commonly sodium and potassium thiocyanate, and ammonium thiocyanate salts.

Although any conventional amount of the thiocyanate salts may be added, preferred levels are usually from about 0.1 to 20 grams of thiocyanate salt per mole of silver halide. and 3,320,069. Alternatively, conventional thioether ripening agents may be used, such as those described in U.S. Pat. Nos. 3,271,157, 3,574,628 and 3,737,313.

The flat grain emulsions with high aspect ratio are suitably washed to remove soluble salts. The soluble salts can be removed by well known methods, such as by decantation, filtration and / or cold solidification and leaching, as shown by Research Disclosure, vol. 176, December 1978, paragraph 17643, section II. The emulsions, with or without sensitizers, can be dried and stored before use. In the present invention, washing is particularly favorable for terminating the maturation of the flat grains after completion of precipitation, in order to avoid increasing their thickness, decreasing their width ratio and / or excessive increasing their diameter.

Although the processes for the production of flat silver halide grains described above will give high grain ratio flat grain emulsions in which the flat grains meeting the thickness and diameter criteria for width ratios account for at least 50 percent of the total projected area of the total population of silver halide grains, it is recognized that additional benefits can be obtained by increasing the proportion of such flat grains present. Preferably, at least 70 percent (optimally at least 90 percent) of the total projected area is provided by flat silver halide grains that meet the criteria of thickness and diameter. Although smaller amounts of non-flat grains are fully compatible with many photographic applications, the proportion of flat grains can be increased to achieve the full benefits of flat grains.

Larger, flat silver halide grains can be mechanically separated from smaller, non-flat grains in a mixed population of grains using conventional separation procedures, for example by centrifugation or hydrocyclone. An example of hydrocyclone separation is shown in U.S. Pat. No. 3,326,641.

In accordance with established practice in the art, it is possible to mix the emulsions with flat grains with a high aspect ratio with each other or with conventional emulsions to meet special requirements on the emulsions. For example, it is known to mix emulsions to adjust the characteristic curve of a photographic element to fulfill a particular purpose. Mixture can be used to increase or decrease the maximum densities achieved during exposure and development, to increase or decrease the minimum density, and to adjust the shape of the characteristic curve between its toe and shoulder. Conventional silver halide emulsions suitable for use in mixing are described by Research Disclosure, vol. 176, December 1978, paragraph 17643, paragraph I.

The present high grain ratio silver halide emulsions are suitably chemically sensitized. They can be chemically sensitized with active gelatin, as shown by THJames: The Theory of the Photographic Process, 4th Edition, Macmillan, 1977, pages 67-76, or with sensitizers with sulfur, selenium, tellurium, gold, platinum. , palladium, iridium, osmium, rhodium, rhenium or phosphorus or combinations of these sensitizers, such as at pAg levels from S to 10, pH levels from S to 8 and temperatures from 30 to 80 ° C, as shown by Research Disclosure, vol. 120, April 1974, item 12008, Research Dísclosure, vol. 134, June 1975, item 13452, U.S. Pat. 761,267, 3,857,711, 3,565,633, 3,901,714 and 3,904,415, and British Patent Specification 1,396,696. Chemical sensitization is optionally carried out in the presence of thiocyanate compounds at levels up to 10 15 20 25 30 35 40 450 797 20 '2 mole percent, based on the silver, as described in U.S. Pat. No. 2,642,361, sulfur-containing compounds of the type described in U.S. Pat. Nos. 2,521,926, 3,021,215 and 4,054,457. presence of final modifiers (chemical sensitization), ie compounds known to suppress haze and increase sensitivity when present during chemical sensitization, such as azaindenes, azapyridazines, azapyrimidines, benzothiazolium salts and sensitizers such as inhalants one or more heterocyclic nuclei. Examples of final modifiers are described in U.S. Pat. 1966), New York, pp. 138-143. In addition or alternatively, the emulsions can be reduction sensitized, e.g. with hydrogen, as disclosed in U.S. Pat. Nos. 3,891,445 and 3,984,249, by treatment with low pAg (eg less than S) and / or high pH (e.g. higher than 8) , such as stannous chloride, thiourea dioxide, polyamines and amine boranes, as described in U.S. Patent 2,983,609, Oftedahl et al: Research Disclosure, vol. 136, August 1975, item 13654, and U.S. Pat. Nos. 2,188,688, 2,739,060, 2,743,182, 2,743,183, 3,026,203 and 3,361,564. U.S. Pat. Nos. 3,917,485 and 3,966,476.

The silver halide emulsions with flat grains with a high width ratio can be sensitized spectrally. It is possible to use spectral sensitizing dyes which show maximum absorption in the blue and minus-blue, ie green and red, parts of the visible spectrum. In addition, for special applications, spectral sensitizing dyes can be used that enhance the spectral response outside the visible spectrum.

For example, the use of infrared absorbing spectral sensitizers is possible.

The silver halide emulsions with high grain ratio grains can be spectrally sensitized with dyes from various groups, including the polymethine dye group, which includes cyanines, merocyanins, complex cyanines and merocyanins (ie tri-, tetra- and polynuclear cyanines, merocyanins) and merocyanins). U: 10 15 20 25 30 35 40 H in 450 797 oxonols, hemioxonols, styryls, merostyryls and streptoir cyanines.

The spectrally sensitizing cyanine dyes comprise two methine bonded basic heterocyclic nuclei, such as those derived from salts of quinolinium, pyridinium, isoquinolinium, SH-indolium, benzhejindolium, oxazolium, oxazolinium, thiazolinium, thiazolium, thiazolium, thiazolium, thiazolium linium, imidazolium, imidazolinium, benzoxazolium, benzothiazolium, benzoselenazolium, benzimidazolium, naphthoxazolium, naphthothiazolium, naphthoselenazolium, dihydronaphthothiazolium, pyrylium and quaternary type imidazopyrazinium.

The spectrally sensitizing merocyanine dyes comprise a basic, heterocyclic cyanine dye-type core and a methane-linked acid core, such as can be derived from barbituric acid, 2-thiobarbituric acid, rhodanine, hydantoin, 2-thiohydantoin, 2-thiohydantoin, 4-piohydantoin, -5-one, 2-isoxazolin-5-one, indane-1,3-dione, cyclohexane-1,3-dione, 1,3-dioxane-4,6-dione, pyrazoline-3,5-dione, pentane -2,47dione, alkylsulfonylacetonitrile, malononitrile, isoquinolin-4-one and chroman-2,4-dione.

One or more spectrally sensitizing dyes may be used. Dyes with sensitization maxima at wavelengths throughout the visible spectrum and with extremely varying shapes for the curve of spectral sensitivity are known. The choice and relative proportions of dyes depend on the range of spectra for which sensitivity is desired and on the shape of the desired spectral sensitivity curve. Dyes with overlapping spectral sensitivity curves will often in combination give a curve in which the sensitivity at each wavelength in the overlap range is approximately equal to the sum of the sensitivities of the individual dyes. It is thus possible to use combinations of dyes with different maxima to obtain a spectral sensitivity curve with a maximum between sensitivity maxima of the individual dyes.

Combinations of spectrally sensitizing dyes can be used which cause supersensitization, i.e. spectral sensitization which in any spectral range is greater than that of any content of that of the dyes alone or that which would be obtained from the additive action of the dyes. Supersensitization can be achieved with selected combinations of spectral sensitizing dyes and other additives, such as stabilizers and anti-fogging agents, developing accelerators or inhibitors, coating aids, brighteners and antistatic agents. One of several mechanisms, as well as associations that can bring about supersensitization is discussed by Gilman: "Review of the Mechanisms of Supersensitization", Photographic Science and Engineering, vol. 18, 1974, pp. 418-430.

Spectral sensitizing dyes also affect the emulsions in other ways. Spectral sensitizing dyes can also act as anti-fogging agents or stabilizers, inducing accelerators or inhibitors, and halogen acceptors or electron acceptors, as disclosed in U.S. Patents 131 US and 930,860. the blue sensitivity of silver bromide or bromoiodide in emulsion layers intended to record exposure to blue light, significant benefits can be obtained by using spectral sensitizers even where their substantial absorption is in the spectral range for which the emulsions have an inherent sensitivity.

For example, it is particularly appreciated that benefits can be obtained from the use of blue spectral sensitizing dyes. Even when the emulsions according to the invention consist of silver bromide and silver bromoiodide emulsions with flat grains with a high aspect ratio, very large increases in sensitivity are obtained by using blue spectral sensitizing dyes. When the intention is to expose the emulsions of the present invention in their range of intrinsic sensitivity, advantages in sensitivity can be achieved by increasing the thickness of the flat grains.

Useful blue spectral sensitizing dyes for silver bromide and silver bromoiodide emulsions with high aspect ratio flat grains can be selected from any of the dye groups known to provide spectral sensitizers. Polymethine dyes, such as cyanines, merocyanines, hemicyanins, hemioxonols and merostyryls, are preferred blue spectral sensitizers. Generally useful blue spectral sensitizers can be selected from these dye groups by their absorption properties, ie hue. However, there are general structural connections that can serve as a guide in the choice of usable bladder sensitizers. In general, the shorter the methine chain, the shorter the wavelength of the sensitization 10 15 20 25 30 35 40 23 450 797 maximum. Nuclei also affect absorption. An addition of fused rings to cores tends to favor longer wavelengths for absorption. Substituents can also change absorption properties.

Useful spectral sensitizing dyes for sensitizing silver halide emulsions include those described in Research Disclosure, vol. 176, December 1978, paragraph 17645, section III.

Conventional amounts of dyes can be used in spectral sensitization of the emulsion layers containing non-flat silver halide grains. To achieve the full benefits of the present invention, it is convenient to adsorb spectral sensitizing dye to the flat grain surfaces in an optimal amount, i.e., in an amount sufficient to provide at least 60 percent of the maximum photographic sensitivity that can be obtained. obtained from the grains under possible exposure conditions. The amount of dye used will vary with the specific dye or dye combination selected, as well as the size and width ratio of the grains.

It is known in photography that optimal spectral sensitization is obtained with organic dyes at 25 to 100 percent or more of single layer coverage of the total available surface area of surface sensitive silver halide grains, as stated, for example, in West et al; "The Adsorption of Sensitizing Dyes in Photo- graphic Emulsions ", Journal of Phys. Chem., Vol. 56, pp. 1065, 1952, Spence et al: "Desensitization of Sensitizing Dyes", Journal of Physical and Colloid Chemistry, vol. 56, No. 6, June 1948, pages 1090-1103, and U.S. Patent 3,979,213. Optimal dye levels can be selected by methods taught by Mees: Theory of the Photographic Process, 1942, Macmillan, pages 1067-1069.

Spectral sensitization can be performed at any stage of emulsion production which is heretofore known to be useful. Spectral sensitization is most commonly performed in the field after completion of chemical sensitization. Specifically, however, it will be appreciated that spectral sensitization may alternatively be performed simultaneously with chemical sensitization, may be performed completely prior to chemical sensitization, and may even begin prior to completion of the precipitation of silver halide grains, as taught by U.S. Pat. Nos. 3,628,960 and 10 As stated in U.S. Pat. No. 4,225,666, it is possible to distribute the addition of the spectral sensitizing dye to the emulsion so that a portion of the spectral sensitizing dye is present before. chemical sensitization, and a remaining portion is added after chemical sensitization. Unlike U.S. Pat. No. 4,225,666, it is possible that the spectral sensitizing dye may be added to the emulsion after 80 percent of the silver halide has precipitated. The sensitization can benefit from adjustment of pAg, including cyclic one, during chemical and / or spectral sensitization. A specific example of pAg adjustment can be found in Research Disclosure, vol. 181, May 1979, punk: 18155. 'It has been quite unexpectedly shown that silver halide emulsions with flat grains with a high aspect ratio can show higher relationships between sensitivity and graininess when sensitized chemically and spectrally than has hitherto been achieved with use. of silver halide emulsions with flat grains and what has been achieved so far using silver halide emulsions with the highest known relationships between sensitivity and graininess.

The best results have been obtained using minus-blue (red and / or green) spectral sensitizing dyes.

In a preferred embodiment, spectral sensitizers may be incorporated into the present emulsions prior to chemical sensitization. Similar results have also been obtained in some cases by adding other adsorbable materials, such as final modifiers, to the emulsions prior to chemical sensitization.

In another variant, which can be carried out in combination with the above variants or separately therefrom, it is convenient to adjust the content of silver and / or halide salts present immediately before or during chemical sensitization.

Soluble silver salts, such as silver acetate, silver trifluoroacetate and silver nitrate, may be added, as well as silver salts which may precipitate on the grain surfaces, such as silver thiocyanate, silver phosphate, silver carbonate and the like. Fine grains of silver halide (ie silver bromide, iodide and / or chloride) that can undergo Ostwald ripening on the flat grain surfaces can be added. For example, a Líppmann emulsion may be added during the chemical sensitization. Chemical sensitization of spectrally sensitized emulsions with flat grains with a high width ratio can be achieved at one or more ordered, discrete points of the deuplate grains. It is believed that the preferential adsorption of spectrally sensitizing dye on the crystallographic surfaces forming the major surfaces of the flat grains enables a chemical sensitization to occur selectively at different crystallographic surfaces of the flat grains.

The preferred chemical sensitizers for the highest achieved relationships between sensitivity and graininess consist of gold and sulfur sensitizers, gold and selenium sensitizers, and gold, sulfur and selenium sensitizers. Thus, in a preferred embodiment, the flat-grained flat-grained silver bromine iodide emulsions defined herein contain an intermediate calcite, such as sulfur and / or selenium, which may be undetectable, and gold, which is detectable.

The emulsions may also contain detectable amounts of thiocyanate, although the content of the thiocyanate in the final emulsions can be greatly reduced by known emulsion washing methods. In various of the preferred embodiments set forth above, the flat silver bromoiodide grains may have another silver salt at their surface, such as silver thiocyanate, silver chloride or silver bromide, although the other salt may be present at levels below those detectable.

Although it is not necessary to achieve all of their benefits; The present emulsions are suitably chemically and spectrally sensitized in accordance with current manufacturing practice. This means that they preferably achieve sensitivities of at least 60 percent of the maximum logarithmic rate that can be achieved from the grains in the spectral sensitization range under the possible conditions of turning and developing. The logarithmic sensitivity is defined here as 100 (1-log E), where E is measured in meter-candela seconds at a density of 0.1 above the veil. Once the silver halide grains in an emulsion have been characterized, it is possible from further product analysis and performance assessment to estimate whether an emulsion layer of a product appears to be optimally chemically and spectrally sensitized relative to comparable commercial products from other manufacturers.

Silver Image Transfer In perhaps the simplest application of the invention, a high width silver grain halide emulsion was used, of the type previously described, instead of the silver halide emulsion layer in a conventional photographic film unit for silver image transfer. In addition to a conventional photographic support, on which the silver grain emulsion layer with flat grains is applied, the film unit for the silver image transfer suitably comprises a silver receiving layer, containing sprouts for physical development of silver halide or other silver precipitants. To produce a transferred silver image, the silver receiving layer and the emulsion layers are applied to each other, and a treatment solution containing a solvent for silver halide is released to be brought into contact with the emulsion and receiver layers after imagewise exposure of the emulsion layer with flat grains.

Extremely variable sprouts or silver precipitants can be used in the receiver layers used in silver image transfer processes. Such sprouts are incorporated into conventional photographic organic colloidal layers, such as layers of gelatin and polyvinyl alcohol, and contain such physical sprouts or chemical precipitants as (a) heavy metals, especially in the form of carbonyl, and salts of these metals, (b) salts, the anions of which form silver salts which are less soluble than the silver halide in the photographic emulsion to be treated, and (c) non-diffusible polymeric materials with functional groups which can be combined with silver ions and render them insoluble.

Typical useful silver precipitants include sulfides, selenides, polysulfides, polyselenides, thiourea and its derivatives, mercaptans, stannous halides, silver, gold, platinum, palladium, mercury, colloidal silver, aminoguanidine sulfate, aminoguanidine carbonate, arinoguanidine carbonate , sodium stannite, substituted hydrazines, xanthates and the like. Poly (vinyl mercaptoacetate) is an example of a suitable non-diffusing polymeric silver precipitant. Heavy metal sulfides, such as sulfides of lead, silver, zinc, aluminum, cadmium and bismuth are useful, especially when the sulfides of lead and zinc alone or in a mixture, or complex salts thereof with thioacetamide, dithiooxide or dithiobiuret. The heavy metals and the precious metals, especially in colloidal form, are particularly effective. Other silver precipitants will be apparent to those skilled in the art. 10 15 20 25 30 35 40 21 450 797 The treatment solution may be designed as a conventional silver halide developer, containing a silver halide solvent. Examples of treatment solutions which contain silver halide solvents and which are useful for producing transferred silver images in combination with these film units for photographic image transfer are those described in U.S. Pat. Nos. 2,352,014, 2, S43 181, 2,861,885, 3,020,155. and 3,769,014.

In the film image transfer unit, the emulsion and receiver layers may be connected in any suitable, conventional manner. The emulsion layer or layers and the receiving layer may be applied to the same carrier or to different carriers. When the receiving layer is applied to a separate carrier, the layer and the carrier together with any additional layer present are collectively referred to as a recipient. In a common, preferred design for separation, the substrate supporting the emulsion layer is opaque, and the carrier of the receiver is reflective (eg white) or provided with a reflective layer below the receiver layer. Exposure occurs before the receiver and the emulsion layer are applied to each other for development. In a common design in a unit, both the support for the receiver and the one for the emulsion layer are transparent, and a reflective (eg white) background for viewing the silver image is provided by coating the receiving layer with a reflective pigment layer or the pigment is incorporated into the treatment solution. A preferred receiver usually also contains a neutralizing layer (also called a pH lowering or acidic layer) to interrupt the development, and at least one delay layer (also sometimes referred to as a spacer layer or "inert" spacer layer). The neutralization and delay layers may alternatively be applied to the carrier for the emulsion. The carriers for the recipient and the emulsion are preferably in one piece, ie united during exposure, treatment and viewing, but in different designs they may be separated during exposure, viewing and / or part of the treatment. Examples of materials for use in the neutralization and retardation layers are described in Research Dísclosure, 123, July 1974, item 13331, and volume 135, item 13525, July 1975. Details regarding reflective layers and carrier stock. terial, including incorporated ultraviolet absorbents O-optical brighteners, is described in Research Dísclosure, 10 15 20 25 30 35 40 450 797 zs vol. 151, November 1976, item 15162. Specifically preferred, transparent carrier materials are poly (ethylene terephthalate) and cellulose esters. Preferred reflective carriers consist of resin-coated paper substrates.

In a preferred embodiment, the film units according to the present invention contain an alkaline treatment composition and devices for its containment and delivery within the film unit. A preferred device is a removable container (eg a capsule), which is arranged to be so placed during the treatment of the film unit that a compressive force applied to the container by means of pressure-applying devices, such as is present in a camera which is designed for development in the camera, will cause a release of the contents of the container inside the film unit. However, other methods of introducing the alkaline treatment composition may also be used. Options for treatment are further shown by Research Dísclosure, paragraph 17643, cited above, paragraph XXIII, C and G.

Dye Image Transfer The photographic film units for image transfer according to the invention may alternatively provide a transferred dye image. Except as specifically stated, the details of dye image transfer film units may be identical to those of the silver image transfer film units discussed above, and will not be described in detail again.

A silver image transfer film unit can be converted to a dye image transfer film unit only by replacing the silver receiving layer with a dye receiving layer and a material providing a dye image incorporating in the silver halide emulsion layer or in an adjacent layer. Since silver halide is not normally transferred to the receiver layer in a dye image transfer film unit, silver halide solvent does not constitute an essential component of the alkaline treatment solution in a dye transfer film unit.

It is possible to construct a film unit for transferring dye images in accordance with the present invention which can give a monochromatic, Transferred dye image by applying to a support a layer unit which provides a single dye and comprises an emulsion layer of silver halide with flat grains of the previously described type and at least one dye-forming material in the emulsion layer itself or in an adjacent layer in the layer unit. In addition, the film unit for dye image transfer comprises a dye-receiving layer that can graze or otherwise immobilize the dye that migrates to it. To produce a transferred dye image, the emulsion layer with flat grains is exposed graphically, and an alkaline treatment solution is brought into contact with the emulsion layer with the dye receiving and the emulsion layers applied to each other. In a particularly suitable application for monochromatic transferred dye images, a combination of dye imaging materials was used to give a neutral, transferred dye image. This image can be used to enhance the transferred silver image or completely replace it by providing a visible, black-and-white image. Of course, monochromatic, transferred dye images with each hue can be produced if desired. Film units according to the present invention for transferring multicolor dye images use three dye-giving layer units: (1) a layer which gives a blue-green dye, containing a red-sensitive silver halide emulsion, combined with a material which gives a blue-green dye image, (2) a layer unit which gives a purple dye, containing a green-sensitive silver halide emulsion with a combined material which gives a purple dye image, and (3) a layer unit which gives a yellow dye, comprising a blue-sensitive silver halide emulsion with a combined material which gives a yellow dye image . Each of the dye-bearing layer units may contain one, two, three or more separate silver halide emulsion layers, as well as the dye-forming material, applied in the emulsion layers or in one or more separate layers forming part of the dye-giving layer unit. Each or a combination of the emulsion layers may consist of silver halide emulsion layers of the previously described type with flat grains with a high width ratio.

In a preferred embodiment of the invention, at least the most sensitive emulsion layers are constituted in the layer units which provide. blue-green and purple dye of silver halide emulsions of the type described above with flat grains of high width ratio. At least the most sensitive emulsion layer in the layer unit which gives a yellow dye image is also suitably constituted by a silver grain halide emulsion with a high width ratio of the type described above, but a use of other , conventional silver halide emulsions in the layer unit which gives yellow dye together with silver halide emulsions with flat grains with high aspect ratio in the layer units which give blue-green and purple dye is also possible.

Depending on the dye imaging material used, it may be incorporated into the silver halide emulsion layer or into a separate layer combined with the emulsion layer. The dye imaging material may be any of a number known in the art, such as dye coupler, dye developer and redox type dye release agent, and the specificity used will depend on the type of element or film unit and on the type of dye. image desired.

Materials useful in diffusion transfer film units contain a dye moiety and a determining moiety. The determining part is in the presence of the alkaline treatment solution and as a function of the silver halide development responsible for a change in mobility of the dye part. These dye imaging materials may be initially motile and immobilized as a function of the silver halide developer, as described in U.S. Pat. No. 2,983,606. treatment solution as a function of the silver halide development. This latter group of materials includes redox-type dye-releasing compounds. In such compounds, the determining group is a carrier, from which the dye is released as a direct function of the silver halide developer or as an inverse function of the silver halide developer.

Compounds that release dye as a direct function of the silver halide developer are termed negative working liberating compounds, while compounds that release dye as an inverse function of the silver halide developer are termed positive working liberating compounds.

A preferred group of positive working release compounds is the nitrobenzene and quinone compounds described in U.S. Patent No. 4,139,379. In these compounds, the dye moiety is attached to an electrophilic cleavage group, such as a carbamate group, ortho position to the nitro group or quinone acid, and is released upon reduction of the compound by means of an electron donating compound contained in the element or in the treatment composition. In areas where the electron donating compound is consumed by developing silver halide, no dye group is released.

Other useful positive working release compounds are the hydroquinones described in U.S. Pat. No. 3,980,479 and the benzisoxazolone compounds described in U.S. Pat. No. 4,199,354.

A preferred group of negative-working liberating compounds is the ortho- or parasulfonamidophenols and naphthols described in U.S. Patent Nos. 4,054,312, 4 OS 428 and 4,076,529. In these compounds the dye group is attached to a sulfonamido group. which is in the ortho or para position to the phenolic hydroxyl group and is liberated by hydrolysis after oxidation of the sulfonamido compound with development.

Another preferred group of negative working release compounds is ballast, dye-forming (chromogenic) or non-dye-forming (non-chromogenic) couplers having a mobile dye attached to a relaxation point. When coupled with an oxidized dye developer, such as a para-phenylenediamine, the mobile dye is cleaved so that it can pass to a receiver. The use of such negative-working dye-imaging compounds is disclosed in U.S. Pat. Nos. 3,227,50 and 3,227,552, as well as British Pat. Nos. 1,445,797. Since the silver halide emulsions used in the image transfer film units of the present invention work. takes negative, the use of negative-working liberating compounds will give negative transferred dye images. To obtain a positively transferred dye image using negative working release compounds, known film unit variations for image reversal and processing variations can be used, as shown in U.S. Patent Nos. 3,998,637 and 4,258,117.

Any material can be used as a dye-receiving layer in the film units of the present invention as long as it will graze or otherwise immobilize the dye which diffuses into it. The optimal material chosen will of course depend on the specific dye or dyes to be grazed. The dye-receiving layer may also contain ultraviolet absorbers to protect the dye image from fading due to ultraviolet light, brighteners and similar materials to protect or enhance the dye image. A polyvalent metal, suitably rendered immobile by combination with a polymer, may be applied in or to the receiver layer to chelate the transferred image dye, as disclosed in U.S. Patent Nos. 4,239,849 and 4,241,163. and materials for their preparation are described in Research Disclosure, No. 15162, and U.S. Patent 4,258,117.

The alkaline treatment composition used in the film units for transferring dye images may be an aqueous solution of an alkaline material, such as an alkali metal hydroxide or carbonate (eg sodium hydroxide or sodium carbonate) or an amine (e.g. diethylamine). Preferably, the alkaline composition has a pH above 11. Suitable materials for use in such compositions are described in Research Disclosure, paragraph 15162, mentioned above.

A developer is suitably included in the alkaline treatment composition, although it may be included in a separate solution or treatment sheet, or may be incorporated into some layer of the film unit which may be permeated by the treatment solution.

When the developer is separated from the alkaline treatment composition, the alkaline composition serves to activate the developer and provide a medium in which the developer can come into contact with and develop silver halide.

Various silver halide developers can be used in developing the film units of the present invention. The choice of an optimal developer will depend on the type of film unit with which it is used and on the specific dye imaging material used. Suitable developers may be selected from such compounds as hydroquinone, aminophenols (eg N-methylaminophenyl), 1-phenyl-3-pyrazolidinone, 1-phenyl-4,4-dimethyl-3-pyrazolidinone, 1-phenyl-4-methyl -4-hydroxymethyl-3-pyrazolidinone and N, N, N ', N'-tetramethyl-p-phenylenediamine. The non-chromogenic developers in this list are preferred for use in dye transfer film units, as they have a reduced tendency to dye recipient layers for dye images. All of these developers are also useful in film units for silver transfer. 10 15 20 ZS 30 35 40 33 450 797 Effect of flat grains on developing speeds “-f One of the surprising advantages of the present invention is the speed with which the transmitted image becomes visible. The rapid availability of the visible transferred image can be directly attributed to the presence of one or more silver halide emulsions of the type defined here with flat grains with a high aspect ratio. Without binding to any particular theory, it is assumed that the geometric configuration of the flat silver halide grains results in the rapid availability of the transferred images. The geometry of the flat grains gives the silver halide grains a very high surface area in comparison with their volume, and this in turn is assumed to affect their development rate. In image transfer processes, it is the image variation in the development of the silver halide grains as a function of their image exposure that affects the transferred image. In some systems, such as those using negative-working liberating compounds of the type previously described, the development of silver halide is directly associated with transferred imagery. The faster the silver halide is developed, the faster the images are made available for viewing. In other systems, such as the silver image transfer and dye image transfer systems, in which positive working release compounds of the type previously described are used, the development of the silver halide constitutes or controls a competing reaction which delays the transfer of image material and accounts for minimum density in the considered the picture.

When the development of silver halide is accelerated, the mechanisms responsible for the transfer of imagery and with which the development of silver halide competes and thereby affects can also be accelerated.

The use of flat grains to reduce the time required between the onset of development and the acquisition of a visible transmitted image, i.e. the arrival time, in no way prevents the use of conventional features in image transfer film units known to reduce the access time. When the present invention is used in combination with conventional features to reduce access time, at least additive results are normally to be expected. In addition, there are also additional features which are unique to the film units for image transfer according to the present invention and which can contribute to a reduced access time. A breast advantage which can be achieved with the film units according to the present image transfer invention and containing at least one emulsion layer with silver haloiodide (preferably silver bromoyodide) with flat grains with a high aspect ratio is the variation in the transmitted image as a function of temperature. This reduced variation in the transferred image is a direct result of the use of one or more flat grain emulsion layers, as described above, when the flat grains contain at least about 2 mole percent iodide. Without binding to any particular theory, it is believed that the flat silver halide iodine grains exhibit less variation in their rates of development as a function of temperature.

In car transfer systems, in which the development of silver halide is directly connected to transferred image materials, this reduced temperature dependence of flat silver halide grains directly leads to a reduced variation in the observed image. In systems which are also based on competing reactions to produce the visible image, the reduced variation in the development of silver halide as a function of temperature may reduce variations in the transmitted image to the extent that it can be attributed to variations in silver halide development and to the extent that it compensates for temperature variations in the competing reactions used in image generation.

Effect of Flat Grains on Silver Coating It has surprisingly been observed that the film units of the present invention for transferring dye images exhibit significantly higher photographic sensitivities at higher silver coatings than comparable conventional film units for transferring dye images. It is well known to those skilled in the art that silver coatings below a threshold value result in a decrease in observed photographic sensitivity, determined from a transferred dye image. Although the sensitivity decreases as the silver coatings of silver halide emulsions decrease, the sensitivity decrease is much more gradual when flat grain emulsions with a high width ratio are used, thereby enabling lower silver coatings.

Acceptable photographic sensitivity in conventional film units for the transmission of multicolored images is usually achieved by the use of silver halide in each of the layers which now give yellow, purple and blue-green dye at silver coatings of about 1000 mg / m2 or higher. It is possible to use substantially lower silver coatings in the practice of the present invention. When the silver halide grains in the emulsion in the layer unit giving yellow, purple or blue-green dye in the film unit of the present invention for transferring dye images are flat as described above, the emulsions can be effectively used at silver coatings from 150 to 750 mg / m 2, preferably from 200 to 700 mg / m2, and optimally from 300 to 650 mg / m2. At higher and lower silver coatings, higher and lower photographic sensitivities will be achieved, and the indicated ranges illustrate an effective balance between photographic performance and silver coatings for most imaging applications. When the image transfer film unit contains a single dye layer unit containing flat silver halide grains, these coatings are applicable to those of a layer unit which gives a single dye. When all three dye-bearing layer units contain silver halide emulsions with flat grains, at least additive savings of silver can be achieved.

Layer Arrangement The image transfer film units of the present invention can use any layer arrangement of arrangement heretofore known to be useful in conventional image transfer film units having one or more radiation-sensitive silver halide emulsion layers. In addition, the specific properties of flat-grain silver halide emulsions make it possible to use extremely favorable arrangements of the layer arrangement which have not hitherto been known in the art. The following specific arrangements of the layering are illustrative only, and many other arrangements are also possible: 'To avoid unnecessary repetition, the discussion of each of the successive arrangements of the layering is limited to features which are characteristic in comparison with prior art. arrangement of the layering. In other words, details and advantages shared by the arrangements of the layering order are completely discussed only in connection with the first arrangement of the layering order in which they occur. If a detail or an advantage is not shared by an arrangement of the layer arrangement described below, this is emphasized in particular. 10 15 20 ZS 30 450 797 36 Layer order I r_: Laminated and removable film unit according to the invention for silver image transfer.

Reflective carrier Silver-receiving layer Image display Cf. Silver halide emulsion layer with flat grains Carrier Layer I shows a conventional, detachable laminate-type film unit for silver image transfer. Upon image exposure, the negative working silver halide emulsion layer with flat grains produces a developable latent image. The silver-receiving layer, containing precipitating nuclei, is palaminated, and an alkaline treatment composition, not shown, is released between the silver-receiving layer and the emulsion layer containing latent pixels occurs upon contact with the alkaline treatment composition. Silver halide solvents included in the treatment composition dissolve the silver halide grains not developed. The dissolved silver halide migrates to that of the silver-receiving layer, where physical development occurs. A positively transmitted silver image is achieved in the silver-receiving layer. The treatment is terminated by stripping the reflective carrier with the silver receiving layer applied thereto from the remainder of the image transfer film unit.

Although the arrangement of the layer arrangement is conventional and uses conventional materials with the exception of the flat grain silver halide emulsion layer, substantially superior results can be obtained. The access time required to generate a visible silver image in the receiver layer is significantly reduced. It is assumed that this can be attributed to specific benefits provided. is made of flat silver halide grains. Primarily, the flat silver halide grains defined herein are developed at a higher rate than comparable, non-flat silver halide grains. Of at least as great importance is that flat silver halide grains of the present invention can be dissolved at a substantially higher rate than comparable non-flat grains. after exposure. Development of the flat silver halide grains ”10 15 20 ZS 30 35 37 450 797 Although the two treatment mechanisms of development and solubilization can fully account for the faster access of the image in layer order I, a third property of flat grain emulsions can also be used. to further reduce the access times for the image. Although flat grain emulsion layers with a high width ratio can be applied in the same layer thicknesses as conventional emulsions without departing from the scope of the invention, it is preferred to make the silver halide emulsion layers with high grain width ratio thin compared to the corresponding conventional silver halide emulsion. In conventional silver halide emulsion layers used in image transfer, the thickness of the emulsion layer is considerably larger than the average grain diameter calculated from the projected areas of the grains. Furthermore, the thickness of the layer is large enough to accommodate not only the average grains, but the largest grains present. Thus, if the largest non-flat silver halide grains in a silver halide emulsion layer in an image transfer film unit have an average diameter of from 1 to 2 μm, the emulsion layer will have a thickness of at least 1 to 2 μm, and will usually be substantially thicker. On the other hand, it is possible to use flat silver halide grains of the type defined here with diameters based on projected average areas of 1 to 2 μm and often even larger, while the thickness of the flat grains is less than 0.5 or even 0. 3 pm. In an example of an emulsion in which the flat grains have an average thickness of 0.1 μm with an average diameter of 1 to 2 μm, the thickness of the silver halide emulsion layer can be easily reduced considerably below 1 μm. The present flat grain grains emulsion layers with a high width ratio are suitably less than 4 times the average thickness of the flat grains, and are optimally less than twice the average thickness of the flat grains. Significant reductions in the thickness of the silver halide emulsion layers with flat grains with a high aspect ratio can contribute to a reduction in access times for the image by reducing the length of diffusion paths. Furthermore, a reduction in the length of the diffusion pathways can also contribute to improvements in sharpness.

Layer arrangement II Film unit according to the invention in one piece for silver image transfer. 10 15 45Û 797 33 Considering _ '»lf Transparent carrier Neutralization layer Delay layer Silver-receiving layer.

Reflective layer Opaque layer Emulsion layer with flat silver halide grains Alkaline treatment composition + opacifying agent Transparent carrier Imaging exposure The arrangement of the layer arrangement II is a conventional film unit for silver image transfer, and differs from the prior art in silver. Layer order II combines all the advantages provided by the emulsion layer with flat silver halide grains and discussed above in connection with layer order I, and also provides the advantages known in the art of a unit in one piece.

Due to the presence of an opacifying agent in the alkaline treatment solution, it is necessary to apply the alkaline treatment solution to the indicated location after visual exposure. Once in place, the opacifying agent prevents further exposure of the emulsion layer, as may occur, for example, when the image transfer film unit is removed from a camera. The barge call is terminated by the delay and neutralization layers.

Layer arrangement III Film unit according to the invention in one piece for monochromatic transfer of color images 10 15 20 pp. 450 797 Considering = AJ, Transparent carrier Dye-receiving layer Opaque layer Silver halide emulsion layer with flat grains Transparent composition carrier 'F Visual exposure At first the alkaline treatment composition with constituent opacifying agent is not present at the site shown. » During pictorial exposure, therefore, light strikes the silver halide emulsion layer with flat grains. This gives a latent image, corresponding to the areas of the emulsion layer struck by light. To initiate development, the alkaline treatment composition is applied at the indicated location. Usually, but not necessarily, the film transfer film unit is removed from the camera in which it is exposed, immediately after the alkaline treatment composition and the opacifying agent have been applied in place. The opacifying agent and the opaque layer together prevent further exposure of the emulsion layer.

Upon development, a mobile dye or compound to a dye is released from the emulsion layer. When the color-g substance-forming material constitutes a positively working, liberating compound; the initially exposed areas of the emulsion layer are released, and when the dye-forming material constitutes a negative-working release compound, the opposite occurs. The mobile dye or pre-compound of the dye penetrates the opaque layer and the reflective layer, and is otherwise grazed or immobilized in the dye-receiving layer to enable viewing through the top, transparent carrier. The development is terminated by the delay and neutralization layers. It is possible to convert the layer arrays I and IIh into film units for transferring monochromatic dye images by incorporating a dye imaging material into the high grain ratio halide emulsion emulsion layer, a dye receiving silver being used instead of the silver layer. the receiving layer, and an alkaline treatment composition is used which is suitable for transferring dye images. Thus, in the case of possible layer sequences, monochromatic transferred dye images can be easily obtained by modifying layer orders I and II. If these modifications were to be made, Layer III would still differ from Layer II in terms of the location of the delay and neutralization layers. The locations of the delay and neutralization layers in Layers II and III are interchangeable. Although not specifically shown, it is possible to combine both silver image and dye image transfer in a single image transfer film unit, since the two are combinable. A useful application for such a combined film unit for image transfer arises when the silver density is enhanced by dye, which enables the use of low silver coatings. With the exception of combined images of silver and dye, dissolution of undeveloped silver halide is not normally performed in layer order III and is not required to achieve reduced access times for the transferred image. The presence of dye imaging materials in the silver halide emulsion layer with high grain width ratio can significantly increase the thickness of this layer. As discussed above, it will be appreciated that the silver halide coatings may be substantially reduced in the high width ratio silver halide emulsion layer while maintaining acceptable photographic sensitivity values in film units for transferring dye images. Layer order III can provide this advantage.

Layer arrangement IV Film unit according to the invention in one piece for transferring a multicolored dye image 10 41 450 797 'v Imaging exposure "- Transparent carrier Neutralization layer Delay layer Composition Alkaline treatment composition + opacifying agent Transparent topcoat Green-sensitive silver halide emulsion layer with flat grains Material layer that gives a purple dye image Intermediate layer with binding agent Red-sensitive silver halide emulsion layer with flat grains I Material layer that gives a blue-green dye image Opaque layer Reflective layer Dye-receiving layer contain three separate dye-bearing layer units, each containing a silver halide emulsion layer with a high-width flat grain grain and a dye-b refractory material layer, instead of the only silver halide emulsion layer with flat grains with a high width ratio and containing dye-forming materials in the layer order III. Whether the dye imaging material is applied in the emulsion layer itself or in an adjacent layer in the layer arrangements III and IV is a matter of choice, and either of the arrangements is possible.

To prevent color contamination of adjacent dye-laying layer units, an intermediate layer containing a bonding member is provided between dye-laying layer units. The use of interlayer binders is taught by U.S. Pat.

The use of binding agents is possible in either or both places.

In a modification of the layer order IV, it is possible to eliminate the intermediate layers. Since the high-width flat-grained silver halide emulsion layers can be extremely thin compared to conventional silver halide emulsion layers typically used in multicolor dye image film transfer units, each of the high-width silver grain halide emulsion layers can be applied with .

The two layers of material which give a purple dye image suitably do not contain a binding agent, but may, if desired, contain binding agents, depending on the sensitivity to color contamination in the imaging manufacture and on the specific choice of the dye imaging materials. By arranging dye-forming layers on both sides of each J silver halide emulsion layer with flat grains with a high aspect ratio, it provides a close connection between the dye-forming materials and the silver halide. This arrangement is most suitable when the dye-imparting materials in each dye-imparting layer unit are initially colorless or at least changed in color tone so that the dye-imparting material does not adsorb in the spectral range for which the silver halide is intended to react.

When the material that gives the yellow dye image is initially yellow, it, together with the blue-sensitive silver halide emulsion layer with flat grains with a high aspect ratio, acts to stop blue light that would otherwise achieve them. green and red sensitive silver halide emulsion layers with flat grains with high width ratio. When the green and red sensitive silver halide emulsion layers use grains of silver bromide or silver bromoiodide in a conventional film unit to transfer a multicolored dye image, it is necessary to stop blue light to prevent color contamination of the green and red sensitive emulsion layers. When the green and red sensitive emulsions are made of flat grains with a high aspect ratio as defined herein, it is not necessary to filter blue light so that it weakens before it reaches these emulsion layers. Thus, when the yellow dye imaging material is initially colorless or at least does not absorb in the blue spectral range, it is still possible to obtain a true color reproduction in the layer units which produce purple and blue-green dye without the need for an intermediate yellow filter layer. As further described in more detail below, the dye-giving, color-forming layer units may be arranged in any desired order.

Layer order V_, Film unit according to the invention in one piece for transferring a multicolored dye image - 'Opaque carrier Material layer which gives a yellow dye image Blue-sensitive silver halide emulsion layer with flat grains Intermediate layer with binding agent Material layer which gives blue-green dye layer purple dye image Green-sensitive silver halide emulsion layer in with; p1atta grains Transparent overlay Alkaline treatment composition with reflective material and indicator dye The dye-receiving layer Delay layer »Neutralization layer Transparent carrier image the indicator dye, not at the indicated site, but released to the displayed site after exposure to allow treatment. The indicator dye shows a high density at the elevated pH levels at which development takes place. 10 15 20 25 30 35 40 450 797 44 It therefore protects the silver halide emulsion layer from further exposure if the film unit is removed from a camera during the treatment. Once the neutralization layer lowers the pH of the film unit to interrupt the development, the indicator dye returns to a substantially colorless form. The alkaline treatment composition also contains a reflective material, which provides a background for viewing the transferred dye image after development.

Layer arrangement V shows the application of the invention to a one-piece film unit for transferring a multicolored dye image, where imagewise exposure and viewing take place through the same carrier. The arrangement of the layer order V differs from what has previously been learned not only in the use of silver halide emulsions ß ßd flat grains with a high width ratio, but also in the order in which the dye-giving layer units are arranged. The green-sensitive silver halide emulsion layer with flat grains with a high aspect ratio is located closest to the source of exposing radiation; while the blue-sensitive silver halide emulsion layer with flat grains with a high width ratio lies at the far end. This arrangement is possible without color contamination due to the relatively large differences in the sensitivity to blue and to minus-blue which can be obtained with silver halide emulsions with flat grains with a high width ratio and which are spectrally sensitized in minus-blue. By applying the purple dye layer unit closest to the source of exposing radiation and closest to the dye receiving layer, the sharpness of the purple dye image is improved and its access time is reduced. The purple dye image is of course the visually most important component of the multicolored dye image. The blue-green image is visually the second most important, and its position is also closer to the exposing source of radiation and the dye-receiving layer than in a corresponding, conventional film unit for transferring dye images. Thus, significant advantages in terms of reduced access time for the image and increased image sharpness can be achieved with the arrangement of the layer order V in addition to the improvements which can be attributed to the flat silver halide grains with high aspect ratio and which have been discussed above in connection with other arrangements. of layering.

Although the layer order V is useful with all silver halides with high grain ratio flat grains, it is particularly suitable with silver bromide or bromoiodide with high grain ratio flat grains.

Layer order VI Film unit according to the invention in one piece for multicolor dye image transfer with car reversal Exposure ~ L Transparent carrier Neutralization layer Delay layer Alkaline treatment composition Green-sensitive silver halide emulsion layer with flat grains Intermediate layer grains e Meiienekikr with binding agent Blue-green_color-imaging material and sprouts Intermediate layer with binding agent and sprouts Blue-sensitive silver halide emulsion layer with flat grains Intermediate layer with binding agent Yellow-dye-imaging material and sprouts , containing the opacifying agent, not as directed. The alkaline treatment composition is applied to the indicated location to initiate development. From the beginning, each of the silver halide emulsion layers with flat grains with a high width ratio is developed in the areas hit by light during the exposure. The emulsion layers each contain a binding agent to prevent any interaction between the oxidized developer formed by the development of the illuminated silver halide and the dye imaging materials. An intermediate layer containing binder is also interposed between each of the high width ratio flat grain silver halide emulsion layers and its corresponding dye imaging material for this purpose.

In those areas of the high width ratio silver halide emulsion layers where silver halide development does not occur, silver halide is solubilized by a silver halide solvent included in the alkaline treatment composition. The solubilized silver halide migrates through the adjacent interlayer containing binder and is transferred to silver on the sprouts present in the layer containing the dye imaging material. The sprouts may be those used for physical development in the transmission of silver images. The oxidized developer formed as a result of physical development is free to react with the dye-forming material to release a moving dye or a pre-compound into a dye. Dye contamination between adjacent dye-bearing layer units is prevented by applying between them a layer containing a binder to prevent migration of oxidized developer therethrough and germs to prevent migration of solubilized silver halide therethrough.

Layer order VI shows a one-piece film unit for transferring a multicolored dye image, which provides a positive, transferred dye image using negative-working silver halide emulsions and negative-working liberating compounds. Although the basic part has been previously described, as shown in British Patent Specification 904 364, there are unexpected advantages in using silver halide emulsions of the type described here with flat grains with a high width ratio.

It should be noted that both the development and the solubilization of silver halide are required in order to obtain a transferred dye image. Due to the increased rates of development and solubilization possible with silver halide emulsions of the type defined here with flat grains with a high aspect ratio, it is possible to reduce the access times of the transferred image below those previously obtained with this type of car reversal.

Layer order VI also has advantages which can be attributed to an arrangement of dye-giving layer units, similar to that already described for layer order V.

Although the invention has been specifically described with reference to certain special arrangements of layering, it will be appreciated that the silver halide emulsions with high grain ratio with high aspect ratio need not always be present as planar, continuous layers. Instead of being continuous, the layers may be divided into discrete, laterally offset portions or segments. In film units for transferring multicolor images, the layers do not have to be arranged on top of each other, but can be present in the form of layer segments arranged next to each other. It is possible to use silver halide emulsions of the type described here with high grain ratio flat grains in arrangement with microcellular film units for image transfer, as described in the published PCT application WO80 / 01614, published 7 Aug. 1980. The present invention can also be fully applied to microcellular imaging units containing microcells which are improvements to published PCT application WO80 / 01614, such as British Patent Application 2,091,435 and U.S. Patent 4,307,165.

Although all of the advantages attributable to high grain ratio silver halide emulsions can be achieved in microcellular film units for image transfer, the major differences between the minus-blue and blue sensitivities that can be obtained with spectrally sensitized silver-halide emulsions with high aspect ratio, especially then silver bromide and bromoiodide emulsions, especially advantageous in microcellular film units for image transfer, which are intended to provide multicolor images. Since the triads of microcells designed to react to blue, green and red light are arranged to receive the same incident light, intermediate yellow filters are arranged using conventional silver bromide and bromoiodide emulsions to improve the differences in sensitivity between minus -blue and blue. This may include additional coating or cell filling steps and reduce photographic sensitivity. The silver halide emulsions with flat grains with high aspect ratio defined here 15 15 20 25 30 35 40 450 797 48 can be used in microcellular film units for multicolor image transfer without the use of yellow filters, so that the performance is significantly simplified and performance is improved.

As will be apparent to those skilled in the art, the image transfer film units may contain various conventional additives, which have not been specifically discussed above. For example, the image transfer film units may contain brighteners, anti-fogging agents, stabilizers, dispersing or absorbing materials, hardeners, coating aids, plasticizers, lubricants and matting agents, as described in Research Disclosure, vol. 176, December 1978, paragraph 17643, paragraphs V, VI, VIII, X, XI, XII and XVI. Methods of additives and coating and drying procedures may be used, as described in paragraphs XIV and XV.

Conventional photographic carriers can be used, as described in paragraph XVII. Other combinable, conventional features, which are not specifically described, will be readily apparent to those skilled in the art.

In further applications submitted at the same time as the present one, material referred to in the foregoing is described in further detail. These applications are based on the American applications 320 891, 320 898, 320 899, 320 904, 320 905, 329 907, 320 908, 320 909, 320 910, 320 912 and 320 920.

Example. The invention can be better illustrated by reference to the following illustrative examples. In each of the examples, by percentage is meant percent by weight, unless otherwise indicated, and by "M" is meant molar content, unless otherwise indicated. All solutions consist of aqueous solutions, unless otherwise stated. Although some flat grains with a diameter less than 0.6 μm were included in calculating the average diameters of the flat grains and the percentage projected area in the emulsions according to the examples, there was an insufficient amount of flat grains with a small diameter to significantly change the stated values. , with the exception of when their exclusivity is specifically stated. Example 1. Control Emulsion A-1 A conventional control emulsion of silver bromoiodide with a mean grain ratio having an average grain diameter of 1.1 μm and containing 9 mol% iodide was prepared as described in U.S. Pat. No. 3,320,069. The emulsion was optimally sensitized with sulfur and gold in presence of thiocyanate, and was spectrally sensitized to green light using a supersensitizing combination of carbocyanine dyes.

Emulsion B with flat grains A silver bromide emulsion with flat grains with a high width ratio, containing flat silver bromide grains with an average grain diameter of 4 μm, an average grain thickness of 0.13 μm and an average width ratio of about 30: 1 was prepared. The flat silver bromide grains accounted for approximately 90 percent of the total projected grain area. The emulsion was chemically sensitized optimally with sulfur and gold in the presence of thiocyanate, and spectrally sensitized with the same supersensitizing dye combination used in control emulsion A-1. Film units for dye image transfer The control emulsion A-1 was applied to a support provided with an anti-light layer in a series of decreasing silver coverage (1.38, 0.69, 0.53 and 0.36 g / m2) together with the materials shown below. : Coverage Redox dye release agent 1 0.69 g / m2 Incorporated reducing agent 2 0.42 g / m2 Inhibitors 3-10 g / m2 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene 1, 2 g / mol Ag celarin 1.1 g / mz In addition to the above-mentioned gelatin, an equal amount of gelatin was also present in the layer per gram of silver in the layer.

The flat grain emulsion B was applied to a clear cellulose acetate support in a series of decreasing silver coatings (1.3S, 0.67 and 0.40 g / m 2) together with the materials shown below. Redox Coating Release Coverage 1 0.80 g / mz Incorporated reducing agent 2 0.37 g / m2 inhibitor 0.01 g / mz 4-hydroxy-6-methyl-1,3,3a, 7- 3,6 g / mol Ag 1.2 g / ml Except the above-mentioned gelatin, per gram of silver in the layer tetraazainden Gelatin tet there was an equal amount of weight of gelatin also present in the layer. 45Û 797 so Redox dye release agent 1 (PRDR-1) -Å 0 H R2 \ ./ '\ ./ Rl L' 'J Rl / \ ñ / \ Rz CH: CH: | ..._ | / \ RI I -CH "\ .-.%" (I: 'CHS CH: CH: I l.' MN-O% \ ø / \ c Czz fl zs' 1 U 1 | ¿- \ \, / \ / RI CH2N'C00'i II * f \ so = m1 = fa 'O / \ ./ CH; N-COCF; 1 J \, / dispersed in diethyllauramide with solid material solvent 1: 1> Incorporated reducing agent 2 ( IRA-2) OH.,., / \ ._ _ ./.\./1\./CONH(CHg)§Û '\ .-. / CSE-ll _t_' J l \ _âl \ _% CH: CsH11'E II NHCOCHCO -? - CH: 1H; CCOO CH: dispersed in diethyl lauramide solid product solvent 2: 1 S 20 Inhibitor 3 (INH-3) * Å CH: 1 'N / cnzncos - < _; Q = Ö E-CxzHzs \ / \ ._Û _ .. u N \ - scoNcH = / \ ü / \ C12H == - 9.

N 'l 0 1 I \ CH: / AV * ä \ _ / II: Ä' * ß Dispersed in diethyl lauramide; means 2: 1 Receiver for dye image The receiver for the dye image consisted of the following structure. The coverage is given in parentheses in g / mz. Hydroxyethylcellulose layer (Natrosol ZSOL) (0.97) p. Gelacin layer (1,1) “4. Opaque layer: Carbon (1,9), gelatin (1,1) p. Reflective layer: witandioxia (19), gelatin '(s, o) 2. Grazing layer: Poly (4-vinylpyridine) (2.2), gelatin (2.2) 1. Metal-containing layer: Nickel sulphate hexahydrate (0.58), gelatin (1.1) solid material solution Placed on a clear polyester carrier in the order shown by the numbering.

Exposure and development The above-described film units for color image transfer were exposed for 1/100 second to a 600 watt incandescent lamp at 28S0 ° K as a light source through a step wedge, a 1.0 neutral density filter and a Wratten 16 filter. The film units for transferring dye images were developed by releasing treatment fluid from a capsule to the interface between the dye receiver and the emulsion layer by lamination between stainless steel rollers to obtain a layer of developer having a thickness of 75 .mu.m. The treatment composition of control emulsion A-1 (capsule L) is shown below in Example 2. The composition of the capsule of emulsion B with granules was identical to capsule L, except that it contained 16 g / l of 3-pyrazolidinone as electron transfer agent instead of 8 g / l.

In both cases, transmissions were performed for 10 minutes at room temperature of 79Û 797 H. The receivers were separated, and the green density = according to Status A was read. Characteristic curves were set, and relative sensitivities were determined at 0.2 density units below the maximum density.

The obtained sensitometric results are shown below.

Of particular interest are the relative threshold velocities at decreasing silver coatings for the two emulsions. The emulsion layer with flat grains maintained significantly higher relative sensitivities when the silver coverage was reduced compared to the conventional emulsion layer with three-dimensional grains. 11 šâlåí fi š 'om 11mm Kmltfast âeäåïiišhet * Control emulsion Arl 1.38 g / mz 1.74 0.16 1.7 100 0.69 g / mz 2.04 0.17 2.2 ss, 0.53 g / m? 2.11 0.13 2.4 51 m6sgmF z fl s omk zß m fi uåiïšfïoïnmed 1.35 g / m2 1.04 0.12 1.2 100 0.67 g / m2 1.44 0.12 1.0 90 0, 40 g / mz 1.72 0.10 2.1 ss * 30 = 0.3 log E Impact is shown Example 2. also graphically in figure 1 Control emulsion A-2 A conventional, polydisperse silver bromoiodide emulsion with a low width ratio and containing a part large grains up to about 2 microns, and containing 6.2 mole percent iodide, were prepared as described in U.S. Patent 3,320,069. The emulsion was optimally chemically sensitized with sulfur and gold in the presence of thiocyanate, and spectrally sensitized to green light using the same sensitizers used for the flat grain emulsion, flat grain emulsion C, which is described below.

Emulsion C with flat grains A silver bromoiodide emulsion with flat grains with a high width ratio, which contained flat grains with an average grain diameter of 4.7 μm, an average grain thickness of 0.16 μm and an average width ratio of 29: 1 was prepared. The flat silver bromo- 10 15 20 25 30 35 Ü 450 797 iodide grains accounted for more than 95 percent of the total projected grain area. The emulsion was optimally chemically sensitized with sulfur and gold in the presence of thiocyanate, and was spectrally sensitized to green light using a supersensitizing combination of carbocyanine dyes.

Film units for transferring dye images One-piece image receivers (IIR) using the above emulsions were prepared with the following structure. The coverage is stated in g / m2, unless otherwise stated. 7. Hydroxyethylcellulose (Natrosol ZSOL) as topcoat (0.54) 6. Purple image layer: Green-sensitized, negative silver halide emulsion C with flat grains (0.74 Ag), redox dye release agent 1 (0.67), reducing agent 2 (0.36), inhibitor 3 (0.009), 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindenes (3.5 g per mole of Ag), gelatin (1.7). Gelatin intermediate layer (1,2). opakt skikt; Koi (1.9), geiaein (1.2). Reflective layer: Titanium dioxide (16.0), gelatin (2.6). Grazing layer: Poly (4-vinylpyridine) (2.2), gelatin (2.2). Metallic layer: Nickel sulphate hexahydrate (0, S8), gelatin (1,1) The layers were applied in the specified number order on a -lhJLNJÄUï clear polyester support.

A control sample was similar to the coating in the example described above, except that the control emulsion A-2 was used in an amount of 1.48 g Ag / m2. Both coatings were cured with bis (vinylsulfonyl) methane at 1.1 percent by gelatin weight.

Coatings were prepared with the following structure: 2. Delay layer: Physical mixture 1: 1 of the following two polymers, applied with 4.8 g / m2: polymers of acrylonitrile, vinylidene chloride and acrylic acid in the weight ratio 1427927, and the carboxyester lactone formed by a copolymer of vinyl acetate and maleic anhydride in the presence of 1-butanol to give a partial butyl ester with acid azester = 15:85 1. Acidic layer: Copolymer of n-butyl acrylate and acrylic acid in a weight ratio of 30:70, equivalent to 149 mec acid / m2 The layers were applied in the specified number order on a clear polyester carrier. 10 15 20 ZS 30 450 797 54 Treatment capsules were prepared with the following two compositions: Capsule L Capsule M Potassium hydroxide 60 g / l 60 g / l 4-hydroxymethyl-4-methyl-1-phenyl--3-pyrazolidinone 8 g / l 6 g / l Potassium bromide 5 g / l 10 g / l Sodium sulphite 2 g / l 2 g / l Carboxymethylcellulose 57 g / l 57 g / l gg exposure and development Each of the one-piece (IIR) image receivers was exposed to a sensitometer to give a full-scale Dmin / Dmax image after development with a viscous treatment composition in a capsule. The treatment composition was spread between the IIR and the cover sheet using a pair of rollers which gave a gap of 100 μm.

Within 12 to 24 hours, the green density according to Status A of the receiving side of the IIR was read to obtain the sensitometric curves. The sensitometric parameters Dmax, Dmín, contrast and relative sensitivity (at D = 0.3 below Dmax) were read from the curves.

As can be seen from the following data, the flat grain emulsion C with either capsule L or the less active capsule M gave a relative sensitivity that was 0.2 log E faster than a control emulsion treated with the same capsule, despite the much lower silver coating ( 0.74 g Ag / mz compared to 1.48 g Ag / m2) of the emulsion with flat grains. The difference in sensitivity was even greater, 0.4 log E when comparing the two emulsions at almost equal maximum densities. Under the direct viewing conditions (magnification 1: 1) normally used for products of this type, there was no difference in graininess which was visible on visual inspection. 10 15 20 25 450 797 SS Emulsion Capsule DG-max DG-min Green- Relatlv _ contrast gronkansllghet Control sample A-2 L 1.3 0,13 1,4 100 Bu fl sion Cned flat grain L 1,8 0,13 2,0 119 Kbntroll test A-2 M 1.6 0,13 1,6 77 Emulsion C with 0 flat grains' M 1,9 0,13 1,8 99 Ekqggl 3. A multicolored one-piece image receiver (IIR) was produced with the following structure: _ 11. Top layer 10. Yellow-colored image layer 9. Intermediate layer 8. Purple-colored image layer: Green-sensitized, negative 7. 6. 5. 4. 3.

Z. 1. silver bromoiodide emulsion D with flat grains (a fresh preparation of the emulsion C with flat grains) (0.65 Ag), redox dye release agent 1 (0.63), reducing agent 2 (0.32), inhibitor 3 (0.010 ), 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene (3.6 g / mol Ag), gelatin (1,3) Intermediate layer Blue-green car layer Gelatin intermediate layer Opaque layer Reflection layer Grazing layer: Po1y (4-vinylpyridine) (2.2), gelatin (2.2).

Metal-containing layer: Nickel sulphate hexahydrate (0.58), gelatin (1.1) The layers were applied to a clear polyester support in the order of number indicated.

A control sample was similar to the example, but used a low width ratio silver bromoiodide emulsion A-3 at 0.99 g Ag / m 2 in layer 8, the purple car layer.

Both the sample and the control sample were cured with bis (vinyl ¥ sulfonyl] methane in 0.9 percent by weight of the gelatin. Des: The cover sheet was the same as used for Example 2.

Treatment capsules with the following composition are prepared - Capsule N = * Potassium hydroxide 60.0 g / l 4-hydroxymethyl-4-methyl-1-p-tolyl-3-pyrazolidinone 12.0 g / l Potassium bromide 5.0 g / l Ethylenediaminetetraacetic acid, disodium salt 10.0 g / l Carboxymethylcellulose 57.0 g / l The above elements were used as follows: The one-piece multicolor image receiver (IIR) was exposed in a sensitometer to give a neutral image at a density according to Status A of 1.0 after treatment with a viscous treatment composition in a capsule. The contents of the capsule were spread between the IIR and the cover sheet using a pair of rollers which gave a 100 μm gap. Within 12 to 24 hours, the green density according to Status A was read on the receiving side of the IIR to obtain the sensitometric curve. The sensitometric parameters of the green density, D contrast and relative sensitivity _ max 'Dmin' (at D = 0.2 below Dmax) were read from the curve.

The data given below show that the emulsion D with flat grains had a relative sensitivity which was almost 0.3 log 5 higher than the control sample, but still used only 2/3 of the amount of silver. Under the direct viewing conditions (121 magnification) used for products of this type, no significant difference in "observed graininess" could be seen here when viewed through a green filter.

Emulsion Capsule Dé-max DG-min Green Relative contrast green sensitivity Kbntroll test A-3 'N 1.9 0.12 1.5 100 Em fl sim1Dned plata' grains _ N 2.0 0.23 1.4 127 Example 4. Emulsion E with flat grains A silver chloride emulsion with flat grains with a high width ratio and containing flat grains with an average grain diameter of 6.0 μm, an average grain thickness of 0.28 μm and with an average width ratio of 22: 1 was prepared. The flat silver chloride grains accounted for more than 80 percent of the total projected area. The emulsion was chemically optimally sensitized with sulfur and gold in the presence of thiocyanate, and was spectrally sensitized to green light with an oxacarbocyanine dye in the presence of 3 mole percent bromide.

Film units for dye image transfer Single-piece image receivers (IIR) used emulsion E with flat grains, but were otherwise identical to those in Example 2.

The cover sheet and capsules L and N are the same as those in Examples 2 and 3. g The above elements were used in the same manner as described in Example 2.

An IIR as above using emulsion E gave an image with D / D min max sensitometer at 1/100 second through a full scale stepped test object when exposed to an Eastman IB density. This indicates that the emulsion E had a sufficient photographic sensitivity to be considered suitable for use with "camera sensitivity" with image transfer material.

Sensitometric parameters are given in the following table: Emulsion Capsule DG-max DG-min Green- - in contrast EL 1.6 fl0.3 1.1 'EN 1.0 0.31 0.7 Example 5. Emulsion F with flat grains En value emulsion of silver bromine iodide with flat grains with high width ratio, which was sensitized by epitaxial deposition of silver chloride, and containing flat grains with an average grain diameter of 3.0 μm, an average grain thickness of 0.09 μm, and with an average width ratio of 33: 1 was produced.

The flat grains accounted for more than 85 percent of the total grain area.

A one-piece image receiver (IIR) was prepared in a manner similar to that of Example 2, except that in layer 6 the emulsion F with flat grains was used (0.67 Ag), and that layer 5 was omitted. Q The cover sheet and capsule N were the same as in Examples 2 and 3.

The above elements were used in the same manner as described in Example 2.

The prepared IIR using emulsion F gave a full scale Dmín / Dmax image upon exposure in an Eastman IB sensitometer at 1/100 second through a test object of stepped density. This shows that the emulsion F had a sufficient: photographic sensitivity to be considered suitable for use in "camera sensitivity" with image-transmitting material.

Sensitometric parameters are given in the following table.

Emulsion Capsule DG-max DG-min Green contrast FN 2,0 = 0,1 2,1 Example 6. Emulsion G, an AgBrI emulsion (97: 3 molar ratio between Br and I) with flat grains had an average diameter of cough plate the grains of 1.6 μm, an average thickness of the flat grains of 0.10 Pm and an average width ratio of 1621, and I more than 80 percent of the total projected area of the grains were provided by the flat grains.

This emulsion was optimally chemically sensitized with 100 mg of sodium thiocyanate per mole of Ag, 9.0 mg of sodium thiosulfate pentahydrate per mole of Ag and 3.0 mg of potassium tetrachloroaurate per mole of Ag, and was spectrally sensitized optimally for the green area with a green absorbing carbocyanine dye.

A control emulsion of AgBrI (97: 3), designated as control emulsion C-6, of the type described in U.S. Pat. No. 3,320,069, had an average grain diameter of 0.81 μm, an average grain thickness of about 0.55. pm, and an average width ratio of 1,511.

The control emulsion C-6 was optimally chemically sensitized with 1.2 mg of sodium thiosulfate pentahydrate per mole of Ag and 0.4 mg of potassium tetrachloroaurate per mole of Ag, and was optimally sensitized spectrally to the green area of the spectrum with the same green absorbing carbocyanine dye used above.

A single color one-piece image receiver (IIR) having the following structure was prepared using the flat grain emulsion G described above and the control emulsion C-6. Coverage is stated in g / m2. 7. Top coat: Bis (vinylsulfonyl) methane (0.071), gelatin (0.54) 6. Silver halide layer: Green-sensitized silver bromoiodide emulsion (3% I) with flat grains, emulsion G, (0.81 Ag), PRDR-1 (0.67), IRA-2 (0.32), inhibitor 3 (0.043), gelatin (1.6) 5. Gelatin layer (4.8) 4. Opaque layer: Carbon (1.9), gelatin (1 , 3) 10 15 20 25 30 35 S9 450 797 3. Reflective layers: Titanium dioxide (17), gelatin (2,6) No. 2. Grazing layers: Poly (4-vinylpyridine) (2,2), gelatin (2, 2) 1. Metallic layer: Nickel sulphate hexahydrate (0.58), gelatin (1.1) The layers were applied to a clear polyester support in the order number indicated.

A monochromatic control coating of the same structure was prepared, except that layer 6 had the green-sensitized control emulsion C-6 of silver bromoiodide (3 $ I) (0.81 Ag).

Capsules were prepared with the following composition: Potassium hydroxide 55.0 g / l; Electron transfer agent (ETA): 4-hydroxymethyl-4-methyl-1-p-tolyl-3-pyrazolidinone 15.0 g / l Potassium bromide 4.0 g / l Ethylenediaminetetraacetic acid 7.8 g / l Sodium sulfite 2.0 g / l 1 Carboxymethylcellulose 56.0 g / l Carbon 165.0 g / l Anionic surfactant (Tæm fl 80 * 2.0 g / l Blyoid 0.4 g / l * The sodium salt of a condensate of formaldehyde and naphthalene sulfonic acid "Tamol" is a trademark Cover sheets were prepared as described in Example 2.

The monochrome IIR, containing either emulsion G or 'C-6, was exposed in a sensitometer through a stepped density test object at 1/200 second with neutral density filtration, sufficient to give a full scale Dmax / Dmin image after development with a viscous treatment composition in a W capsule. The contents of the canister were spread at room temperature (23 °) between IIR and the cover sheet using a pair of opposite rollers with a gap of 100 μm. After a period of at least 24 hours °, the receiver side of the IIR was read with a density according to Status A and a computer-integrated conversion curve over D towards log E was obtained. are given in the following table: Sensitometric parameters from this inversion curve 10 15 20 450 797 so Emulsion Contrast * äšåâïâšheï Dmin Dmax (Example) G 3.2 100 0.22 1.8 (Control) C-6 2.0 99 0.22 1 , 6 * The contrast is measured from the density 0.2 over D-min to 0.2 below D-max. f The relative sensitivity is measured at density = 30 = 0.3 log E The data obtained show that the emulsion according to the example with flat grains with a high width ratio had a significantly higher contrast compared to a three-dimensional emulsion with equivalent sensitivity. The Dmín values were the same, and the experimental emulsion also had the additional advantage of a slightly higher Dmax. The toe and shoulder parts were equal. Higher contrast at a given silver coating is a highly desirable property in products with "camera sensitivity" of this type for direct viewing of the image.

Example 7. a one-piece (IIR) having the same structure as in Example 6 (but 0.5, Two series of monochromatic, image-receiving elements in layer 6 deflections) was prepared using the flat grain emulsion G and the control emulsion C -6, optimally sensitized as described in Example 6.

Silver halide layer 6: Green-sensitized silver bromoiodide emulsion G (3% I) with flat grains or green-sensitized control emulsion C-6 of silver bromoiodide (3% I), dispersions of image-forming reagents are given in the following table: Emulsion Emulsion G Control emulsion acc. Example C-6 cg / mZJ (m2) Silver coverage, (see following table) 0.08-0.97 0.08-0.97 PRDR-1 0.67 0.67 IRA ~ 2 0.11 0.15 Inhibitor 0.086 0.17 celatin 1, 6 1, 6 10 15 20 25 51 '450 797 Capsules were prepared as in Example 6, except that they contained 20.0 g / l of ETA and 2.0 g / l of potassium bromide.

The same cover sheet was used as for example1.2. The same procedure was used as in Example 6, except that the exposure time was 1/50 seconds. šlgcâlcçåâäing Dšnsítet av gšö? color sensitive- max min sensitivity * hot ** Emulsion G with flat grains 0.97 g / mz 1, ss 0.16 198 0.6s g / mz 1.70 0.17 187 0.32 g / mz 1.07 0.18 163 as' 0.16 g / mz 1.93 0.24 139 Control emulsion C-6 0.97 g / mz 0.63 0.16 - 0.6s g / mz 1.63 0.16 100 0.32 g / mz 1.98 0.17 130 09 0.16 g / mz 0.03 0.41 91 * 30 units of 0.3 lo E, measured at approximately 0.3 density units below Dmïx ** Over the range 0.16 to 0.54 g / m2 Emulsion veil is indicated by a reduced D-max of transferred dye-I substance. A high D-min indicates an insufficient degree of oxidation of the IRA by developing silver halide to prevent reduction of? RDR by the IRA. At the silver halide coverage of 0.65 g / m 2, both emulsions had almost equal threshold velocity. At 0.95 g / mz, a lot of veil to have a meaningful sensitivity value. When the silver halide values decreased, the control emulsion gave too much through the range to 0.16 g / m2, both emulsions gave a good image separation, but the control emulsion decreased by 89 units in sensitivity, while the emulsion with flat grains lost only 48 units.

In these two comparisons, the levels of IRA and inhibitor peat (which is released visually in the unexposed area and thus suppresses the veil) are markedly different. Significantly lower levels of IRA and inhibitors are required for the flat grain emulsion to give comparable results at any value for silver halide coverage. Therefore, less of the photographic reagents is required.

When the control emulsion was applied with the same low levels of w IRA-2 and inhibitor 3 as the flat grain emulsion, the three higher values were completely veiled (D-max = 0.17 to 0.22 ).

Appendix The following details relate to the precipitation of emulsions: Emulsion B To an aqueous solution of bengelatin and 0.17 molar potassium bromide (1.5% gelatin, solution A) at pBr 0.77 and SSOC was added with stirring by double jet at constant flow rate for 0.5 minutes (using 0.06% of the total amount of silver nitrate used) aqueous solutions of potassium bromide (1.51 molar, solution B-1) and silver nitrate (1.0 molar, solution C -1). (In all emulsion preparations, the contents of the reaction vessel were stirred vigorously during the addition of silver salt). The additions of solutions B-1 and C-1 were stopped, and the emulsion was kept for 5 minutes at pBr 0.77 and 55 ° C.

The solution C-1 was then added at a constant flow rate to a pressure of 1.14 at ss ° c, yielding 3.49% of the total amount of silver nitrate used. The addition of solution C ~ 1 was stopped.

Aqueous solutions of potassium bromide (4, S2 molar, solution BÄZ) and silver (2.0 molar, solution c-2) are then added by double jet at an accelerated flow rate (6.5 X from start to finish, ie 6.5 times faster at the end than at the beginning) at pßr 1.14 and ss ° c until the solution c-2 has run out (about 64 minutes, with 93.0% of the total amount of silver nitrate used). The addition of solution B-2 was stopped.

An aqueous solution of silver nitrate (2.0 molar, solution C-3) was then added until pBr 1.51 at SSOC was reached, yielding 3.42% of the total amount of silver nitrate used. 6.45 moles of silver nitrate were used to prepare this emulsion.

Finally, the emulsion was cooled to 35 ° C and coagulated by the method of U.S. Patent 2,614,929.

Emulsion C- 7.0 liters of an aqueous solution of bengelatin and 0.17 molar gelatin, solution A) at pH 2.0 and 70 ° C were prepared. To the solution A, adjusted to pBr 0.77 at sodium bromide (17.1% pH 40 and 70 ° C), was added by the double jet method at a constant flow rate for 4 minutes (0.67 % of the total amount of silver nitrate used) aqueous solutions of sodium bromide (0.45 molar, solution B-1) and silver nitrate (0.10 molar, solution C-1) The addition of solutions B-1 and C-1 was stopped, and the reaction vessel was kept for 2 minutes at 70 ° C.

Solutions B-1 and C-1 were then added to solution A while maintaining pBr 0.77 at a constant flow rate while simultaneously adding at half the flow rate an aqueous solution of sodium bromide (3.78 molar, solution B-2) and silver nitrate. (2.72 molar, solution C-2) to solutions B-1 and C-1, respectively. When solutions B-I and B-2 have run out. (about 29 minutes, 81.8% of total amount of silver nitrate used) the addition of solution C-1 was continued until pBr 1.15 was reached.

The addition of solutions C-1 and CZ was stopped. An aqueous solution of sodium iodide (0.13 molar, solution D) was then added at a constant flow rate for about 2.5 minutes. After solution A was kept for 2 minutes at 70 ° C and pBr 1.02, the addition of solutions C-1 and C-2 was continued until they ran out (17.6% of the total amount of silver nitrate consumed). The total addition time for solution C was about 43 minutes. The final pBr in the reaction vessel was about 1.83. 6.0 moles of silver nitrate were used to prepare this emulsion. The emulsion was cooled to 40 ° C and coagulated and washed in the same manner as for emulsion B. Emulsion D Prepared in a manner similar to emulsion C.

Emulsion E 2.0 liters of an aqueous solution of a copolymer of 3-thiapentylmethyl acrylate, acrylic acid and 2-methacryloyloxyethyl-1-sulfonic acid and sodium salt in the molar ratio 1: 2: 7 (0.63% polymer, solution A), containing calcium chloride dihydrate (0.50 molar), adenine (0.3S $) and sodium bromide (0.013 molar) at pH 2.6 and SSOC was prepared. To solution A, which was maintained at the initial chloride ion content throughout the process, was added by means of a double jet at a constant flow rate for 1 minute (0.7% of calcium chloride (2.0 molar, solution B) and silver nitrate of the total amount of silver nitrate consumed) aqueous solutions. (2.0 molar, solution C). After the first minute at constant flow rate, solutions B and C were added by double jet at an accelerated flow rate (2.3 X from start to finish) for 15 minutes ($ 18.8 of total the amount of silver nitrate).

After the 15 minute period of accelerated flow rate, solutions B and C were added by double jet at a constant flow rate for about 46 minutes (80, 5% of the total amount of silver nitrate).

An aqueous solution of sodium hydroxide (0.2 molar, solution D) was used to maintain pH 2.6 at SSOC. 4.0 moles of silver nitrate were used to precipitate this emulsion.

To 6.0 liters of a solution of 1.5% gelatin and 0.12 molar of potassium bromide at 5 ° C was added with stirring and by means of a double jet a 2.0 molar KBr solution, containing 0.12 molar of K1, and a 2.0 molar AgNO 3 solution over a period of 8 minutes, during which time pBr was maintained at 0.92 (consumption 5.3% of the total amount of silver nitrate used). The bromide and silver nitrate solutions were then added while maintaining pBr 0.92 with an accelerated flow (6.0 X from start to finish) over 41 minutes (starting at $ 94.7 of the total amount of silver nitrate used). In total, about 3.0 moles of silver nitrate were used. The emulsion was cooled to SSOC, washed by the coagulation method of U.S. Patent 2,614,929, and stored at pAg 7.6, measured at 40 ° C. In the obtained AgBrI emulsion (6 mole percent fi odid) with flat grains, those grains having an average grain size of 3.0 μm, an average thickness of 0.09 μm and a width ratio of 33: 1 accounted for 85% of the projected the area of the grains in the emulsion. 120 g of the AgBrI emulsion prepared as above (0.12 mol) were adjusted to pAg 7.2 at 4000 by simultaneous addition of solutions of 0.1 molar AgNO 3 and 0.006 molar KI. Then 3.0 ml of a 0.74 molar NaCl solution was added. The emulsion was spectrally sensitized with 1.5 millimoles per mole of Ag of anhydro-5-chloro-9-ethyl-5'-phenyl-3,3'-di (3-sulfopropyl) -oxacarbocyanine hydroxide triethylamine salt, and kept under minutes at 40 ° C. Then, the spectrally sensitized emulsion was centrifuged and resuspended in a 1.85 x 10 -2 molar NaCl solution twice. In 40.0 g of the emulsion (0.04 mol), 1.25 mol% of AgCl was precipitated by double jet addition over 65 450 797 2.1 minutes of solutions of 0.55 moles of NaCl and 0.5 molar of n: AgNO 3, during which pAg was maintained at 7.5 at 40 ° C. 15 seconds after the start of the precipitation of AgCl, 0.5 mg Na 2 S 2 O 3 .5H 2 O and 0.5 mg KAuCl 4 / mol Ag were added to the reaction vessel.

In the preparation of each of the emulsions, the contents of the reaction vessel were stirred vigorously during the addition of silver and halide salts.

Claims (1)

A photographic film unit for image transfer, comprising a support, at least one emulsion layer applied to the support, containing a dispersing medium and radiation-sensitive silver halide grains, and an image-receiving layer, known therefrom. that at least SO percent of the total projected area of the radiation-sensitive silver halide grains in at least one emulsion layer is provided by flat silver halide grains with a thickness below 0.5 μm, a diameter of at least 0.6 μm, the diameter of a grain being defined as the diameter of a circle with an area equal to the projected area of the grain, and an average width ratio above 8: 1, the width ratio being defined as the ratio of the diameter of the grain to its thickness. 2. A film unit according to claim 1, characterized in that the receiving layer is arranged next to a second carrier. Film unit according to claim 2, characterized in that the second carrier is a reflective carrier. 4. A film unit according to claim 2, characterized in that the second carrier is transparent. A film unit according to any one of claims 2-4, characterized in that the film unit further comprises an alkaline treatment composition and devices for releasing this composition between the carriers. Film unit according to claim 5, characterized in that the alkaline treatment composition contains a solvent for silver halide, and the receiving layer contains seeds for physical development to promote the physical development of solubilized silver halide. 7. A film unit according to any one of claims 1-6, characterized in that a dye imaging material is present in the emulsion layer or layers or in an adjacent layer. Film unit according to one of Claims 1 to 7, characterized in that the flat silver halide grains account for at least 70 per cent of the total projected area of the radiation-sensitive grains present in the emulsion layer or layers. 67 450 797 9. A film unit according to any one of claims 1-8, characterized in that the silver halide grains consist of silver bromide or silver bromoiodide grains. 10. A film unit according to any one of claims 1-9, characterized in that the flat silver halide grains have an average width ratio of at least 12: 1. A silver image transfer film unit according to any one of claims 1 to 10, comprising a transparent support, at least one emulsion layer applied to the support, containing a dispersing medium and chemically and spectrally sensitized, radiation sensitive silver halide grains, a transparent coating, and a silver receiving layer applied to the coating. for receiving silver; transferred from the emulsion layer by an alkaline treatment composition, containing a solvent for silver halide and arranged between the receiving layer and the emulsion layer, characterized in that at least 70 percent of the total projected area of the radiation-sensitive silver halide grains with the silver halide grains is provided. a thickness less than 0.5 μm, a diameter of at least 0.6 μm, and an average width ratio of at least 12: 1. The film unit according to claim 11, characterized in that it further comprises means for initially enclosing, after image exposure, releasing the alkaline treatment composition between the emulsion layer and the receiving layer, and means for interrupting silver halide development. , placed next to the carrier or cover layer. 13. A film unit according to claim 11 or 12, characterized in that it further contains a reflective layer, arranged next to the receiving layer and between the receiving layer and the emulsion layer or layers. Film unit according to one of Claims 11 to 13, characterized in that the flat silver halide grains have an average width ratio of at least 20: 1. A dye image transfer film unit according to any one of claims 1 to 10, comprising a transparent support, at least one emulsion layer applied to the support, containing a dispersing medium and chemically and spectrally sensitized; 3 radiation sensitive silver halide grains, a dye imaging material, applied in the emulsion layer or the layers or in an adjacent layer, a transparent cover layer, and a dye image receiving layer, applied to the cover layer to receive image dye, transferred by an alkaline treatment composition, placed between the receiving layer and the emulsion layers, characterized at least 70 percent of the total projected area of the radiation-sensitive silver halide grains is provided by flat silver halide grains with a thickness' below 0.5 Pm, a diameter of at least 0.6 Pm, and an average width ratio of at least 12: 1. Film unit according to claim 15, characterized in that it further comprises means for initially enclosing and, after image exposure, releasing the alkaline treatment composition between the emulsion layer and the receiving layer, and means for interrupting silver halide development, provided next to the carrier or cover layer. 17. A film unit according to claim 15 or 16, characterized in that it further comprises a reflective layer, disposed adjacent to the receiving layer and between the receiving layer and the emulsion layer or layers. Film unit according to one of Claims 15 to 17, characterized in that the flat silver halide grains have an average width ratio of at least 20: 1. 19. A film unit according to any one of claims 15-17, characterized in that the emulsion layer provides a silver coating of less than 750 mg / m 2. A film unit for transferring a multicolor dye image according to any one of claims 1-10, comprising a carrier, dye-bearing layer units, applied to the carrier and each f and one comprising at least one dye-imaging material and at least one silver halide emulsion, containing a dispersing medium and radiation-sensitive silver halide grains, the dye-bearing layer units comprising a dye-giving layer unit containing a red-sensitive emulsion and a material which gives a blue-green dye image, a dye-imparting layer unit which contains a green-sensitive emulsion and a material which gives a dye-colored and layer unit containing a blue-sensitive emulsion and a material giving a yellow dye image, and a receiving layer for a multicolor dye image, characterized in that at least 70 percent of the total projected area of the radiation-sensitive silver halide grains in at least one of said emulsions acc breathed from flat silver halide grains with a thickness of less than 0.5 μm, a diameter of at least 0.6 μm and an average width ratio of at least 12: 1. 21. A film unit according to claim 20, characterized in that the flat silver halide grains account for at least 90 percent of the total projected area of the grains in at least one emulsion layer. Film unit according to claim 20 or 21, characterized in that said emulsion is arranged to give a silver coating in the range from 150 to 750 mg / m 2. 23. Film unit according to claim 20 or 22, characterized in that that at least 70% of the total projected area of the radiation-sensitive silver halide grains in each of the green- and red-sensitive emulsions is provided by flat grains with a thickness of less than 0.3 μm, a diameter of at least 0.6 Pm and an average width ratio of at least 20: 1. A film unit according to any one of claims 20-23, characterized in that said emulsion containing the flat grains is a red-sensitive or green-sensitive silver bromide emulsion; optionally containing silver iodide, and is arranged to receive exposing radiation before the remaining silver halide emulsions in the film unit. The film unit for transferring a multicolor dye image according to claim 1, comprising a carrier, dye-giving layer units, applied to the carrier and each comprising at least one dye-imaging material and at least one silver halide emulsion containing a dispersing medium and radiation-sensitive silver halide grains comprising dye-giving layer unit containing a red-sensitive emulsion and a material giving a blue-green dye image, a dye-giving layer unit containing a green-sensitive emulsion and a material giving a purple-colored dye image, and a dye-giving layer unit containing a blue-sensitive emulsion and material giving a yellow dye image, and a transparent coating, a dye receiving layer, applied to the support or to the coating, an alkaline treatment composition, means for releasing the treatment composition into contact with the dye-giving layer units , and means for interrupting silver halide development, applied to the support or cover layer, characterized in that at least 70 percent of the total projected area of the radiation-sensitive silver halide grains present in at least one emulsion is provided. of flat silver halide grains with a thickness of less than 0.5 μm, a diameter of at least 0.6 μm and an average width ratio of at least '12: 1, the silver halide grains in said emulsion being provided with a silver coating of from 150 to 750 mg / m2. The film unit for transferring a multicolor image according to claim 1, comprising a carrier, dye-giving layer units, applied to the carrier and each comprising a positive-working redox dye-release and at least one negative-working emulsion, containing a dispersing medium and radiation-sensitive silver bromide. or bromoiodide grains, the dye-bearing layer units comprising a dye-bearing layer unit containing a red-sensitive emulsion and a material releasing a blue-green redox dye, a dye-giving layer unit containing a green-sensitive emulsion and a material releasing a purple redox dye, and a dye-containing layer containing a blue-sensitive emulsion and a material releasing a yellow redox dye, and In a transparent coating, a dye-receiving layer, applied to the carrier or coating, an alkaline treatment composition, means for releasing the treatment composition to contact -with those dye-giving layer units, and means for interrupting silver halide development, applied; to the carrier or topsheet, characterized in that at least 70 percent of the total projected area of the radiation-sensitive silver halide grains present in the emulsion is provided by flat silver bromide or bromoiodide grains having a thickness of less than 0.3 μm. , a diameter of at least 0.6 μm, and an average width ratio of at least 1211, the grains in each of the emulsions being arranged with a silver coating of from 200 to 700 mg / m 2. Film unit according to claim 26, characterized in that each of the emulsions is applied with a silver tack from zoo 11111 sso mg / m 2. An arrow unit for transmitting a multicolor dye image according to HW '1, comprising 'a carrier, a layer unit giving yellow dye applied to the carrier and' comprising a material giving a yellow dye image and a blue-sensitive, negative-working emulsion, I * a first, transparent intermediate layer containing a bonding agent, a layer unit which gives a blue-green dye applied thereon. first intermediate layer and comprising a material giving a blue-green dye image and a red-sensitive, negative-working emulsion, a second, transparent intermediate layer containing a binder, a layer unit giving a purple dye, applied to the second intermediate layer and comprising a material giving a purple colored dye image and a green-sensitive, negative-working emulsion, each of these emulsions containing a dispersant and radiation-sensitive silver bromide or bromoiodide grains, and a receiving layer for providing a visible, transferred, multicolored dye image after imagewise exposure and development of the emulsions, and characterized in that at least 70 percent of the total projected area of the radiation-sensitive silver halide grains present in at least the green and red-sensitive silver emulsions is provided by the emulsions. or bromine iodide grains with a thickness less than 0, 3 .mu.m and a diameter of at least 0.6 .mu.m, and having an average width ratio of at least 12: 1, the grains in each of the green and red-sensitive emulsion being arranged with a silver coating of from 200 to 700 mg / m 2, and the receiving the layer is arranged closer to the layer unit which gives blue-green dye or the one which gives purple dye than the remaining dye-giving layer units during development. 29. A film unit according to claim 28, characterized in that the dye imaging materials are dye developers. The film unit for transferring a multicolor dye image according to claim 1, comprising an opaque carrier, a layer unit giving yellow dye, applied to the carrier and comprising a positive working material releasing yellow redox dye, and a blue-sensitive, negative working emulsion , a first, transparent intermediate layer, containing binding agent, a layer unit which gives a blue dye, applied to the first intermediate layer and comprising a positive-working material which releases a blue-green redox dye, and a red-sensitive, negative-working emulsion, a second, transparent intermediate layer , containing binding agents, a layer unit which gives a purple dye, applied to the second intermediate layer and comprising a positive-working material which releases a purple-redox dye, and a green-sensitive, negative-working emulsion, each of said emulsions containing a dispersion medium and radiation-sensitive silver bromide or bromoiodide grains, and a t transparent cover layer, a dye-receiving layer; applied to the topsheet, an alkali adhesive treatment composition containing reflective material and an indicator dye which is colored at an alkaline pH and substantially colorless at an acidic pH, means for releasing the treatment composition between the recipient layer and the dye-giving layer units, and means for interrupting , placed few? í fi 'New KÜ “MJ next to the beaver or cover layer, and knnetea: kna: i dširz-lv, to at least: 70 present: of the total projiueraåe aïaan of the radiation-sensitive grains present in the green- and red-sensitive emulsions to- Hancial alfalfa of flat grains with a thickness of less than 0,3 [mu] m, a diameter of at least 0,6 [mu] m, and an average width ratio of mihsñ ïlzí, each of the green and red-sensitive emulsions being coated with a silver coating. 300 to 1. 650 mg / m ”. ..-.._- ~ - ~ .- ~ - ~ -