Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C7/00—Multicolour photographic processes or agents therefor; Regeneration of such processing agents; Photosensitive materials for multicolour processes
  • G03C7/30—Colour processes using colour-coupling substances; Materials therefor; Preparing or processing such materials
  • G03C7/3022—Materials with specific emulsion characteristics, e.g. thickness of the layers, silver content, shape of AgX grains

Definitions

• the present invention relates to color negative photographic recording materials providing improved performance with reduced silver usage.
• a very useful approach to increasing light capture of a grain is to alter the grain morphology.
• Employment of high aspect ratio tabular silver halide emulsions, as described in US Patents 4,439,520, 4,672,027, and 4,693,954, has succeeded in providing a large variety of advantages to color negative photographic recording materials.
• Such advantages include improved speed—granularity relationships, increased photographic sensitivity, higher contrast for a given degree of grain size dispersity, h igher separations of blue and minus blue speeds, less image variance as a function of processing time and/or temperature variances, the capability of optimizing light transmittance or reflectance as a function of grain thickness, and reduced susceptibility to background radiation or airport x-ray radiation damage in very high speed emulsions.
• Silver halide coverages of high speed recording materials that have adequate granularity, regardless of the silver halide grain morphology, degrade the sharpness of underlying layers to an undesirable degree.
• the unrelenting demands for reduced granularity in high speed films result in the virtually complete use of light incident on the photographic recording material. Accordingly, silver halide emulsion coverages are, in practice, increased to the point where further changes do not produce any appreciable net benefit insofar as granularity is concerned.
• overlying layers creates a high angle light that travels substantial lateral distances in a multilayer photographic material, causing reduction of the material's resolving power.
• absorption of on-peak light by overlying layers intercepts light desired to be absorbed in underlying layers, since the incident light is finite in quantity.
• the spectral response of underlying layers can be substantially distorted from their desirable, normal stat by these two processes.
• the broadened spectral response produces less accurate color reproduction, and reduced colorfulness of the rendered image.
• Japanese Kokai No. 63-226651 seeks color negative photographic materials having improved sharpness and lowered sensitivity to background radiation through reduced silver usage. However, density is sacrificed at lower silver coverages.
• the present inventors have surprisingly found that when certain silver halide emulsions are used, the coverage of silver halide in an imaging unit can be substantially reduced below that commonly employed in color negative silver halide photographic elements without sacrificing image density, contrast and graininess and without the need for a special amplification process.
• This permits the preparation of higher speed (ISO speed ⁇ 100) color negative photographic materials that provide performance equal to or better than currently available color negative materials at the same speed while at the same time reducing the amount of silver in the element.
• this invention provides a color negative photographic recording material containing a support and at least two silver halide emulsion imaging units sensitive to different regions of the electromagnetic spectrum, each unit containing a dye-forming coupler, at least one unit:
• (a) comprises from 0.2 to 2.0 g/m 2 , based on silver, of a silver halide emulsion wherein greater than 50% of the projected area of the grains is provided by tabular grains having a tabularity of between 50 and 25,000;
• (b) has a thickness of less than about 4.0 ⁇ m
• (c) comprises no more than 2.0 parts by weight of silver per part of coupler
• the color negative photographic recording materials to which this invention relates typically have an exposure latitude of 2.0 or greater and a contrast (gamma) of 0.9 or less, but that is positive in sign. Exposure latitude and contrast are defined and measured as described in Strobel et al.,
• the use of less silver results in the use of less gelatin, and can result in the use of less coupler, related solvents and/or dispersing agents. This further contributes to the thinning of the layer and provides lowered raw material costs.
• Thinner photographic layers containing reduced silver levels can lead to an increase in the transmission of incident light as well as an improvement in the partition of absorbed light among the spectrally sensitized layers.
• thinner photographic layers containing reduced silver levels can lead to reduced consumption of processing chemicals, notably fixing agents, thereby reducing the cost of disposing of these chemicals.
• the tabular grain silver halide emulsions that are useful in the present invention can be comprised of silver bromide, silver chloride, silver iodide, silver chlorobromide, silver chloroiodide, silver bromoiodide, silver chlorobromoiodide or mixtures thereof.
• These emulsions include (i) high aspect ratio tabular grain emulsions and (ii) thin intermediate aspect ratio tabular grain silver halide emulsions.
• High aspect ratio tabular grain emulsions are those which exhibit an average aspect ratio of greater than 8:1.
• Thin, intermediate aspect ratio emulsions are those in which the tabular grains have an average thickness of less than 0.2 ⁇ m and an average aspect ratio ranging from 5:1 to 8:1.
• the silver halide emulsions can be either monodisperse or polydisperse as precipitated.
• the grain size distribution of the emulsions can be controlled by techniques of
• the high aspect ratio tabular grain emulsions and the thin intermediate aspect ratio tabular grain emulsions, as well as other emulsions useful in this invention, can be characterized by a relationship called “tabularity", which is related to aspect ratio (AR). This relationship can be defined by the following equations:
• ecd is the average equivalent circular diameter of the tabular grains
• t is the average thickness of the tabular grains, where dimensions are measured in micrometers.
• Tabular grains are those having two substantially parallel crystal faces, each of which is substantially larger than any other single crystal face of the grain.
• substantially parallel as used herein is intended to include surfaces that appear parallel on direct or indirect visual
• the grain characteristics described above of the silver halide emulsions of this invention can be readily ascertained by procedures well known to those skilled in the art.
• the equivalent circular diameter of the grain is defined as the diameter of a circle having an area equal to the projected area of the grain as viewed in a photomicrograph, or an electron micrograph, of an emulsion sample. From shadowed electron micrographs of emulsion samples it is possible to determine the thickness and the diameter of each grain as well as the tabular nature of the grain. From these measurements the average
• the projected areas of the tabular silver halide grains meeting the tabularity criteria can be summed.
• the projected areas of the remaining silver halide grains in the photomicrograph can be
• tabular grain emulsion has a tabularity of from 50 to 25,000;
• each imaging unit can be comprised of one or more silver halide emulsion layers sensitive to the same region of the spectrum. It is common with high speed color negative materials of the type to which this invention relates, for each unit to be composed of 2 or 3 layers, which can be adjacent or not.
• At least one of the layers in the unit is, as indicated above, comprised of a silver halide emulsion in which greater than 50% of the projected area is provided by silver halide grains having a tabularity of 50 to 25,000.
• this emulsion is in the most
• the emulsion(s) employed in the other layer(s) can be a non-tabular emulsion or a tabular emulsion that does not satisfy the tabularity criteria enumerated above so long as the projected area criterion for the unit is satisfied. If desired, other silver halide emulsions can be blended with the high tabularity emulsion, so long as the projected area criterion is satisfied.
• the silver halide in these other emulsions can, as with the tabular emulsion, be comprised of silver bromide, silver chloride, silver iodide, and mixtures of halides such as silver bromoiodide, silver chlorobromide and silver chlorobromoiodide.
• Especially preferred silver halides, for all of the emulsions in the element are silver bromoiodides.
• Preferred proportions of iodide are from 3 to 12 mole percent although lesser or greater (up to the limit of iodide solubility in bromide) proportions of iodide can be used.
• the proportions of the halide can be uniform throughout the grain, or the proportions can vary continuously or discontinuously across the diameter of the grain, as in core-shell or multiple structure grains.
• the amount of silver halide in the imaging unit of this invention is from 0.2 to 2.0 g/m 2 , based on silver.
• the recording unit has two or more silver halide layers of different sensitivities to the same region of the visible spectrum it is preferred that the more sensitive layer comprise from about 0.10 to about 1.0 g/m 2 of silver, and the less sensitive layer or layers comprise sufficient silver to meet the total unit imaging requirement as noted above.
• the more sensitive layer can comprise from about 0.20 to about 0.6 g/m 2 of silver.
• silver-to-coupler ratio For example, conventional color negative photographic recording materials utilize a substantial excess of silver as compared to coupler so that a ratio of about 3 parts of silver per part of coupler is commonplace. Utilization of the instant invention permits use of at least one-third less silver using the same amount of image coupler.
• the silver to coupler ratio is 2.0 to 1 or less by weight and can go as low as 0.5 to 1 or lower.
• the element employs a silver to coupler ratio in the range of 0.8:1 to 1.5:1. In determining silver to coupler ratio all of the compounds that couple with oxidized developing agents that are in the unit are counted whether or not they contribute to image density.
• Gelatin is commonly used as a vehicle to suspend silver halide grains and prevent their formation of clumps. Reduction in the amount of silver and the use of lower silver to coupler ratios than heretofore leads to use of less binder or vehicle.
• typical cyan and magenta imaging units in color negative photographic materials contain 2 to 3.3 g/m 2 of gelatin. With the instant invention it is also possible to reduce the level of gelatin usage to about 0.5 to 1.5 g/m 2 .
• color-forming units of this invention have thicknesses of less than 4.0 ⁇ m, with units as thin as 2.0 ⁇ m, or less
• Preferred color-forming units have thicknesses in the range of 2.5 to 3.5 ⁇ m. In measuring unit thickness only the dye-forming silver halide layers are included.
• the photographic elements of this invention preferably contain a development inhibitor releasing coupler, especially in the higher speed layer of a given unit. Typical DIR couplers are described in U.S.
• the advantages of this invention are particularly applicable to the higher speed materials, i.e. 100 ISO and greater.
• the photographic recording materials of this invention are multicolor color elements that contain dye imaging units sensitive to different regions of the electromagnetic spectrum.
• Each unit can be comprised of a single silver halide emulsion layer or of multiple emulsion layers sensitive to a given region of the spectrum.
• the layers of the element, including the layers of the image-forming units, can be arranged in various orders as is known in the art, for example, from U.S. Patents 4,400,463 and
• the element comprises imaging units that yield a cyan, magenta and yellow dye image and the silver halide associated with each unit is sensitized to the complementary region of the
• one or more of the silver halide layers can be false sensitized to a region of the spectrum that is not the complement of the dye produced by the coupler with which it is associated.
• one, two, or three of the imaging units can be sensitized to different portions of the infrared region of the spectrum.
• At least one of the imaging units of the element is an imaging unit having the characteristics defined above. It is preferred that this unit be a magenta dye-forming unit or a cyan dye forming unit since the visual information provided by each of these units is of greater significance than that provided by the yellow dye forming unit. In a preferred embodiment, both of these imaging units have the characteristics described above.
• a typical multicolor photographic recording material comprises a support bearing a cyan dye image-forming unit comprising at least one
• red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler
• a magenta image forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler and a yellow dye
• image-forming unit comprising at least one
• the blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler.
• the layer can contain one or more non-complementary couplers in order to modify perceived photographic performance.
• the recording material is coated on a support and can contain additional layers, such as filter layers, image modifier layers, interlayers, overcoat layers, subbing layers, and the like.
• the maximum image density of at least 2.0 is obtained by processing the element in the way it is intended to be used.
• Image density refers to the density range between Dmin and Dmax of the exposed and processed element. This would be one of the common color negative processes used to develop color negative amateur and motion picture films such as the ECN-2 or C-41 process.
• a typical process is
• Sensitizing compounds such as compounds of copper, thallium, lead, bismuth, cadmium, selunium, iridium and other Group VIII noble metals, can be present during precipitation of the silver halide emulsions.
• the silver halide emulsions can be chemically sensitized.
• Noble metal e.g., gold
• middle chalcogen e.g., sulfur, selenium, or
• the silver halide emulsions can be spectrally sensitized with dyes from a variety of classes, including the polymethine dye class, which includes the cyanines, merocyanmes, complex cyanines and merocyanmes (i.e., tri-, tetra-, and
• Suitable vehicles for the emulsion layers and other layers of elements of this invention are described in Research Disclosure Item 17643, Section IX and the publications cited therein.
• Couplers useful in this invention can be polymeric or nonpolymeric.
• Typical cyan dye forming couplers that are useful in this invention are phenols and naphthols.
• Typical magenta dye forming couplers are pyrazolones and pyrazoloazoles.
• Typical yellow dye forming couplers are acetoacetanilides and benzoylacetanilides. Such dye image-forming
• couplers which can be of the one, two or four equivalent type and can be coated in or adjacent to silver halide emulsion layers to be free to react with oxidized developing agent to form the desired image. Minor amounts of couplers which form
• the imaging unit can contain image modifying couplers and compounds which release development inhibitor
• moieties for development accelerator moieties or bleach accelerating moieties. These moieties are released from such compounds, or from a timing group contained within such compounds, as the result of processing.
• the photographic recording materials of this invention can contain brighteners (Research
• the photographic recording materials can be coated on a variety of supports as described in
• Photographic recording materials can be exposed to actinic radiation, typically in the visible region of the spectrum, to form a latent image as described in Research Disclosure Section XVIII and then processed to form a visible dye image as described in Research Disclosure Section XIX.
• Processing to form a visible dye image includes the step of contacting the element with a color
• Oxidized color developing agent in turn reacts with the coupler to yield a dye.
• a series of color negative, incorporated coupler photographic materials were prepared by coating the following layers in order, on a cellulose triacetate film support.
• the physical properties of the emulsions utilized, the unit silver coverages, silver to coupler ratio, and unit thickness of the magenta units are described in Tables I and II which follow the description of the preparation of the photographic materials.
• a first photographic recording material of the invention was prepared by coating the following layers, in order, on a cellulose triacetate film support bearing a layer of black colloidal silver sol at 0.30 g/m 2 and gelatin at 2.44 g/m 2 .
• red-sensitized tabular silver bromoiodide grains (4.0 mole % I-) at 0.65 gAg/m 2 , gelatin at 1.15 g/m 2 , cyan image-forming coupler D at 0.29 g/m 2 , masking coupler C at 0.029 g/m 2 , and antifoggant
• green-sensitized tabular silver bromoiodide grains (2.4 mole % I-) at 0.52 gAg/m 2 , gelatin at 1.16 g/m 2 , image-forming couplers E at 0.30 g/m 2 and F at 0.13 g/m 2 , DIR coupler B at 0.027 g/m 2 , masking coupler G at 0.069 g/m 2 , and antifoggant 4-hydroxy-6-methyl- 1,3,3a,7-tetraazamdene at 0.008 g/m 2 .
• green—sensitized tabular silver bromoiodide grains (4.0 mole % I-) at 0.39 gAg/m 2 , gelatin at 0.60 g/m 2 , image-forming couplers E at 0.075 g/m 2 and F at 0.032 g/m 2 , DIR coupler H at 0.006 g/m 2 , masking coupler G at 0.017 g/m 2 , and antifoggant 4-hydroxy-6-methyl- l,3,3a,7-tetraazamdene at 0.006 g/m 2 .
• Layer 9 Protective Overcoat and UV Filter Layer - comprising gelatin at 1.22 g/m 2 , silver bromide Lippmann emulsion at 0.11 g/m 2 , UV absorbers at 0.23 g/m 2 , and bis(vinyl- sulfonyl)methane added at 2.0% of total gelatin weight.
• a second photographic recording material of the invention designated Element II, was prepared in a similar manner to Element I.
• Element II A second photographic recording material of the invention
• a third color photographic recording material of the invention designated Element III, for color negative development was prepared by applying the following layers in the given sequence to a transparent support of cellulose triacetate. All silver halide emulsions were stabilized with 2 grams of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene per mole of silver.
• Layer 3 Fast Cyan Layer - Comprising red-sensitized silver iodobromide emulsion (4.1 mol % I-) at 0.495 g/m 2 , cvan dye-forming image coupler D at 0.183 g/m 2 , DIR compound B at 0.019 g/m 2 , BAR compound N at 0.016 g/m 2 , with gelatin at 0.720 g/m 2 .
• Layer 4 Comprising oxidized developer scavenger didodecylhydroqumone at 0.054 g/m 2 , dye
• magenta dye-forming image coupler F at 0.043 g/m 2
• DIR compound H at 0.0097 g/m 2 with gelatin at 0.527 g/m 2 .
• Layer 7 Comprising oxidized developer scavenger didodecylhydroqumone at 0.54 g/m 2 , yellow colloidal silver at 0.022 g/m 2 with 0.645 g/m 2 of gelatin.
• red-sensitized tabular silver bromoiodide grains (6.0 mole % I-) at 1.29 gAg/m 2 , gelatin at 1.73 g/m 2 , cyan image-forming coupler D at 0.23 g/m 2 , DIR coupler K at 0.043 g/m 2 , masking coupler C at
• Layer 4 Slow Magenta Layer - comprising a blend of green-sensitized silver bromoiodide grains, tabular silver bromoiodide grains (3.0 mole % l-) at 0.38 gAg/m 2 , non-tabular silver bromoiodide grains (4.8 mole % I 2 ) at 0.81 g/m 2 , gelatin at 2.15 g/m 2 , image- forming coupler F at 0.59 g/m 2 , DIR coupler H at 0.011 g/m 2 , masking coupler G at 0.059 g/m 2 , and antifoggant 4-hydroxy-
• green-sensitized tabular silver bromoiodide grains (6.0 mole % I-) at 1.23 gAg/m 2 , gelatin at 1.80 g/m 2 , image-forming coupler F at 0.17 g/m 2 , DIR coupler H at 0.011 g/m 2 , masking coupler G at 0.028 g/m 2 , and antifoggant 4-hydroxy-5- methyl-1,3,3a,7-tetraazaindene at 0.015 g/m 2 .
• Layer 9 Protective Overcoat and UV Filter Layer - comprising gelatin at 1.15 g/m 2 , silver bromide Lippmann emulsion at 0.22 gAg/m 2 and bis(vinylsulfonyl)methane added at 2.0% of total gelatin weight.
• each element was exposed for 1/100 of a second to a 600W, 3000°K tungsten light source that was filtered by a
• each element was exposed as the first, except that the exposure time was 0.2 second, to allow determination of the maximum density.
• each element was exposed at 0.2 second and a green Wratten 99 filter was added in order to assess the separation exposure gamma and maximum density. To determine the rms granularity, by the method described in H.C.
• Compensating Filters and a 0.2 neutral density filter.
• the exposed samples were developed for 3.25 minutes in the 6-step development process described above on pages 16 and 17.
• the processed film strips were then evaluated for speed, contrast, net maximum density (Dmax minus Dmin) for both white light and green light exposures and granularity for the magenta color-forming unit.
• Dmax minus Dmin net maximum density
• red-sensitized silver bromoiodide grains a medium size tabular grain emulsion (6.0 mole % I-) at 0.91 gAg/m 2
• a smaller tabular grain emulsion (3.0 mole % I-) at 0.28
• Layer 3 Magenta Layer - comprising one of the five green-sensitizing silver bromoiodide emulsions (4.0 mole % I-) described in
• a second photographic recording material designated Element B, was prepared in a similar manner to Element A with the following modifications to the Magenta dye forming unit.
• bromoiodide emulsion was increased to 0.72 gAg/m 2 .
• Gelatin was increased to 1.86 g/m 2 , and image forming coupler E was increased to 0.72 gAg/m 2 .
• Element C was prepared in a similar manner to Element A with the following modifications to the Magenta dye forming unit.
• Layer 3 Magenta Layer - green-sensitized silver
• Layer 3 Magenta Layer - green-sensitized silver bromoiodide emulsion was increased to 1.73 gAg/m 2 .
• Gelatin was increased to 2.91 g/m 2 .
• the photographic elements were exposed for 1/10 of a second to a 600W, 3000°K tungsten light source that was filtered by a Daylight Va filter to 5500°K and a green Wratten 99 filter through a graduated 0-4.0 density step tablet, and they were processed for 3.25 minutes under the conditions described above.
• the film strips were then evaluated for net maximum density (Dmax-Dmin).

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• Silver Salt Photography Or Processing Solution Therefor (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)

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Cited By (8)

Citations (2)

• 1990
  • 1990-10-10 WO PCT/US1990/005742 patent/WO1991006037A1/en active IP Right Grant
  • 1990-10-10 DE DE69020718T patent/DE69020718T2/de not_active Expired - Fee Related
  • 1990-10-10 JP JP51456390A patent/JP3191936B2/ja not_active Expired - Fee Related
  • 1990-10-10 EP EP90915580A patent/EP0447534B1/de not_active Expired - Lifetime
  • 1990-10-10 CA CA002039726A patent/CA2039726C/en not_active Expired - Fee Related
  • 1990-10-10 AT AT90915580T patent/ATE124793T1/de active

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